test(defaults): keep the reference DDL's DO $$ block whole and skip it on H2

The foreign-key block is PL/pgSQL; the H2 loader in
AssistantDefaultsChangelogTest now splits it as one statement and skips it.
SchemaForeignKeyPostgresTest runs it on real Postgres.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CHANGELOG.md

@@ -1,7 +1,37 @@
 # Changelog
 
+## Unreleased - Foreign keys
+
+- Reference DDL: add the missing foreign keys (conversation tree, usage, data audit,
+  budget accounting, profile skills) with orphan quarantine and their indexes; make
+  `assistant_model.provider_id` `ON DELETE CASCADE`. A Postgres guardrail test fails
+  any declared relation without a foreign key.
+
+## Unreleased - Durable turns
+
+- Renew user-owned run leases with heartbeats, poll cross-replica Stop, enforce
+  hard deadlines, and finalize active runs during graceful shutdown. Recover
+  abandoned runs on replay, active discovery, or the next question.
+- Default to superseding a prior answer in the same conversation. Accept explicit
+  concurrent questions; the per-user cap supersedes the oldest run instead of
+  refusing another question. Per-minute limits and budgets still apply.
+- Add `GET /qqq/v1/assistant/turns/active`, `turn.phase` progress and `startedAt`
+  on `message.start`. Cancel is idempotent and returns HTTP 200.
+- Add the optional `AssistantRunTracker` Jobs tray SPI (no-op by default),
+  pending QQQ core job tracking (#1210).
+- Add the durable-turn schema upgrade; apply it before deploying this runtime.
+  A partial unique index fences duplicate terminal events from concurrent reapers.
+- UI API extension `assistant` 1.2.0 (additive): `turns/active`, the optional
+  `concurrency` on a new turn, 503 `SHUTTING_DOWN`, `turn.phase`,
+  `message.start.startedAt`, cancelReason `SUPERSEDED`. The 429 response stays
+  documented for budgets and per-minute limits; the "answer already in progress"
+  refusal is no longer returned. Cancel keeps 202 documented for older replicas.
+||||||| befb90a
+
 ## Unreleased - Starter defaults
 
+- Every seed changeset's rollback is empty: a seeded row cannot be told apart from a host's own row with the same name, and Liquibase also rolls back changesets it marked ran, so a name-based undo would delete host data.
+
 - Fix the defaults changelog: every precondition is a portable `sql-check` (the formatted-SQL `table-exists` form failed to parse); the policy, budget and prices are seeded only into empty tables and the profile only when no default exists, so an existing host never changes on deploy. The test now runs the changelog through Liquibase 4.33, including an already configured host and a missing table.
 - The Setup card prices the default model the way calls are costed (registry, price rows, configured prices); "Add rows for every table" reads fresh data-access rows.
 

UPGRADE.md

@@ -1,5 +1,74 @@
 # Upgrading qbit-assistant
 
+## Foreign keys (2026-10-14)
+
+Recommended: apply the "Foreign keys" block at the end of
+`docs/schema-postgres.sql` (after the index audit). It is guarded and safe to re-run.
+- Adds the missing foreign keys across the conversation tables, usage, data audit,
+  budget accounting and profile skills, with the indexes they need.
+- Detail rows of a conversation `CASCADE`; the message/turn cycle, usage and the data
+  audit use `SET NULL`, so usage keeps its cost rows when a conversation is deleted.
+- Usage, budget accounting and the data audit hold their provider (`NO ACTION`):
+  disable a provider with history instead of deleting it.
+- `assistant_model.provider_id` changes from `NO ACTION` to `CASCADE`
+  (constraint renamed `fk_assistant_model_provider`).
+- Rows that point at a missing parent are first copied to `qqq_fk_quarantine`
+  (created if absent), then nulled, or deleted for the `NOT NULL` profile-skill
+  links. Check that table after the upgrade.
+
+No code change.
+
+## Index audit (2026-10-14)
+
+Recommended, not required: apply the "Index audit" block at the end of
+`docs/schema-postgres.sql`. It adds six indexes, every one `IF NOT EXISTS`:
+- usage by turn (read on each scheduled run)
+- the three retention date filters (turn events, tool calls, inactive conversations)
+- the two `ON DELETE SET NULL` foreign keys on `assistant_scheduled_run`
+
+No code change.
+
+## Durable turns (Unreleased)
+
+Apply the **Durable turns** block at the end of `docs/schema-postgres.sql` before
+starting the new runtime. It adds nullable `heartbeat_at`, `lease_owner`,
+`cancel_requested_at`, `phase`, `concurrency_mode` and the `(user_id, status)`
+index. A partial unique index on terminal events also prevents two replicas from
+inserting separate `message.end` frames for the same turn. Check for historical
+duplicate terminal frames before applying it (resolve any duplicates through your
+normal migration process). Fresh installs run the full schema, including ALTERs.
+Existing rows with no heartbeat use `started_at` for lease expiry. During the
+first upgrade from a runtime without heartbeats, drain old replicas' turns first:
+a new replica cannot distinguish an old live turn from a dead owner after 45 s.
+
+Defaults: heartbeat 5 s, lease 45 s, hard duration 300 s, force-finalization grace
+20 s, shutdown grace 8 s. Configure these through the corresponding
+`AssistantQBitConfig` withers. Heartbeat must be shorter than the lease. The JVM
+shutdown hook is enabled by default; tests disable `registerShutdownHook` and
+managed hosts may call `runtime.shutdown(Duration)` themselves. Give the process
+termination budget enough time for the configured shutdown grace and persistence.
+
+`POST /conversations/{id}/turns` accepts `concurrency: "supersede" | "concurrent"`
+(case-insensitive). Default `SUPERSEDE` stops prior runs in that conversation;
+`CONCURRENT` permits them. The default per-user cap is now 3; reaching it stops
+the oldest run instead of returning the old in-progress 429. Per-minute and
+budget 429 responses still apply. Superseded turns record `cancelReason=SUPERSEDED`.
+
+Cancel now returns HTTP **200**, including for terminal turns, with the current
+`status`. The OpenAPI fragment retains the old 202 response for mixed-version
+rollouts. Active runs are discoverable through `GET /qqq/v1/assistant/turns/active`;
+reattach through the existing events route. Consumers should recognize
+`turn.phase` and `message.start.startedAt`. Starts during shutdown return
+503 `SHUTTING_DOWN`; clients may retry against a ready replica.
+
+Hosts may wire `AssistantRunTracker` for Jobs tray publication, progress, Stop,
+and terminal notification. It is a no-op by default and all callbacks are
+isolated from turn execution. Tracking ids are local to the owning runtime;
+reaping an already dead owner does not invent another tracking job. Hosts should
+associate their durable tracking row with the supplied turn id. The SPI is a
+stand-in for QQQ #1210.
+||||||| befb90a
+
 ## Starter defaults, setup card and table help
 
 The jar now ships `db/liquibase/qbit-assistant/assistant-defaults.changelog.sql`.

docs/schema-postgres.sql

@@ -577,3 +577,127 @@ CREATE INDEX assistant_scheduled_run_owner ON assistant_scheduled_run(user_id, s
 
 -- X1/Y1: encoded audit filters can exceed the old 500-character record links.
 ALTER TABLE assistant_tool_call ALTER COLUMN audit_href TYPE TEXT;
+
+
+-- Durable turns: apply this additive block before deploying the new runtime.
+-- Like earlier additions, fresh installs run the CREATEs followed by ALTERs.
+ALTER TABLE assistant_turn ADD COLUMN heartbeat_at TIMESTAMP;
+ALTER TABLE assistant_turn ADD COLUMN lease_owner VARCHAR(100);
+ALTER TABLE assistant_turn ADD COLUMN cancel_requested_at TIMESTAMP;
+ALTER TABLE assistant_turn ADD COLUMN phase VARCHAR(64);
+ALTER TABLE assistant_turn ADD COLUMN concurrency_mode VARCHAR(16);
+CREATE INDEX assistant_turn_user_status ON assistant_turn (user_id, status);
+
+-- Fence concurrent orphan reapers at the database boundary. A turn ends once.
+-- Check for pre-existing duplicate message.end rows before applying this index.
+CREATE UNIQUE INDEX assistant_turn_event_terminal ON assistant_turn_event (turn_id)
+   WHERE event_type = 'message.end';
+
+-- Index audit (2026-10-14): lookup, retention and FK paths with no leading index.
+-- ScheduledTurn.cost reads usage by turn on every scheduled run.
+CREATE INDEX IF NOT EXISTS assistant_usage_turn ON assistant_usage (turn_id);
+-- Retention: deleteTurnEventsBefore, clearToolResultsBefore and listConversationsInactiveSince filter by date.
+CREATE INDEX IF NOT EXISTS assistant_turn_event_create_date ON assistant_turn_event (create_date);
+CREATE INDEX IF NOT EXISTS assistant_tool_call_create_date ON assistant_tool_call (create_date);
+CREATE INDEX IF NOT EXISTS assistant_conversation_modify_date ON assistant_conversation (modify_date);
+-- ON DELETE SET NULL children: deleting a conversation or turn would scan scheduled runs without these.
+CREATE INDEX IF NOT EXISTS assistant_scheduled_run_conversation ON assistant_scheduled_run (conversation_id);
+CREATE INDEX IF NOT EXISTS assistant_scheduled_run_turn ON assistant_scheduled_run (turn_id);
+
+-- Foreign keys (2026-10-14). Run on new and existing databases; every step is guarded
+-- and re-runnable. The rules follow how the qbit deletes:
+-- * AssistantStore.deleteConversation (also the retention purge) deletes turn events,
+--   tool calls, feedback, messages, turns, data audit and pending actions, then the
+--   conversation. The conversation's own detail rows CASCADE, so an admin delete of a
+--   conversation cleans up the same way.
+-- * The message <-> turn cycle (turn.user_message_id / assistant_message_id and
+--   message.turn_id) and the other optional pointers are SET NULL. Rows are inserted
+--   parent first, so nothing is deferred.
+-- * assistant_usage keeps its cost rows when a conversation goes (SET NULL), and the
+--   data audit trail is never cascaded into (SET NULL).
+-- * Provider references from usage, budget accounting and the data audit are NO ACTION
+--   (like assistant_turn.provider_id): disable a provider with history, do not delete
+--   it. A provider's model rows are its own (CASCADE).
+-- * assistant_budget_usage.usage_id has no foreign key on purpose: the projection
+--   outlives its usage row so budgets keep counting the spend.
+-- Rows that already point at a missing parent are recorded in qqq_fk_quarantine first,
+-- then nulled (nullable columns) or deleted with the full row recorded (NOT NULL).
+CREATE INDEX IF NOT EXISTS assistant_message_parent_message ON assistant_message (parent_message_id);
+CREATE INDEX IF NOT EXISTS assistant_message_turn ON assistant_message (turn_id);
+CREATE INDEX IF NOT EXISTS assistant_turn_user_message ON assistant_turn (user_message_id);
+CREATE INDEX IF NOT EXISTS assistant_turn_assistant_message ON assistant_turn (assistant_message_id);
+CREATE INDEX IF NOT EXISTS assistant_turn_provider ON assistant_turn (provider_id);
+CREATE INDEX IF NOT EXISTS assistant_tool_call_pending_action ON assistant_tool_call (pending_action_id);
+CREATE INDEX IF NOT EXISTS assistant_feedback_message ON assistant_feedback (message_id);
+CREATE INDEX IF NOT EXISTS assistant_pending_action_turn ON assistant_pending_action (turn_id);
+CREATE INDEX IF NOT EXISTS assistant_data_audit_provider ON assistant_data_audit (provider_id);
+CREATE INDEX IF NOT EXISTS assistant_budget_usage_provider ON assistant_budget_usage (provider_id);
+CREATE INDEX IF NOT EXISTS assistant_profile_skill_skill ON assistant_profile_skill (skill_id);
+CREATE INDEX IF NOT EXISTS assistant_budget_downgrade_model ON assistant_budget (downgrade_model_id);
+CREATE INDEX IF NOT EXISTS assistant_conversation_scheduled_task ON assistant_conversation (scheduled_task_id);
+CREATE INDEX IF NOT EXISTS assistant_model_fallback_model ON assistant_model (fallback_model_id);
+CREATE INDEX IF NOT EXISTS assistant_profile_simple_model ON assistant_profile (simple_model_id);
+CREATE INDEX IF NOT EXISTS assistant_profile_complex_model ON assistant_profile (complex_model_id);
+CREATE INDEX IF NOT EXISTS assistant_profile_classifier_model ON assistant_profile (classifier_model_id);
+CREATE INDEX IF NOT EXISTS assistant_rag_source_embedding_model ON assistant_rag_source (embedding_model_id);
+CREATE INDEX IF NOT EXISTS assistant_scheduled_task_profile ON assistant_scheduled_task (profile_id);
+
+CREATE TABLE IF NOT EXISTS qqq_fk_quarantine (id BIGINT GENERATED BY DEFAULT AS IDENTITY PRIMARY KEY, table_name VARCHAR(100) NOT NULL, column_name VARCHAR(100) NOT NULL, row_id VARCHAR(100), missing_parent_id VARCHAR(100), action VARCHAR(20) NOT NULL, row_data TEXT, changeset VARCHAR(200), quarantined_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP);
+
+DO $$
+DECLARE
+   r   RECORD;
+   old TEXT;
+BEGIN
+   FOR r IN SELECT * FROM (VALUES
+      ('assistant_message',        'conversation_id',      'assistant_conversation',   'CASCADE',   TRUE),
+      ('assistant_message',        'parent_message_id',    'assistant_message',        'SET NULL',  TRUE),
+      ('assistant_message',        'turn_id',              'assistant_turn',           'SET NULL',  TRUE),
+      ('assistant_turn',           'conversation_id',      'assistant_conversation',   'CASCADE',   TRUE),
+      ('assistant_turn',           'user_message_id',      'assistant_message',        'SET NULL',  TRUE),
+      ('assistant_turn',           'assistant_message_id', 'assistant_message',        'SET NULL',  TRUE),
+      ('assistant_turn_event',     'turn_id',              'assistant_turn',           'CASCADE',   TRUE),
+      ('assistant_tool_call',      'conversation_id',      'assistant_conversation',   'CASCADE',   TRUE),
+      ('assistant_tool_call',      'turn_id',              'assistant_turn',           'CASCADE',   TRUE),
+      ('assistant_tool_call',      'pending_action_id',    'assistant_pending_action', 'SET NULL',  TRUE),
+      ('assistant_feedback',       'conversation_id',      'assistant_conversation',   'CASCADE',   TRUE),
+      ('assistant_feedback',       'message_id',           'assistant_message',        'CASCADE',   TRUE),
+      ('assistant_pending_action', 'conversation_id',      'assistant_conversation',   'CASCADE',   TRUE),
+      ('assistant_pending_action', 'turn_id',              'assistant_turn',           'SET NULL',  TRUE),
+      ('assistant_data_audit',     'conversation_id',      'assistant_conversation',   'SET NULL',  TRUE),
+      ('assistant_data_audit',     'turn_id',              'assistant_turn',           'SET NULL',  TRUE),
+      ('assistant_usage',          'conversation_id',      'assistant_conversation',   'SET NULL',  TRUE),
+      ('assistant_usage',          'turn_id',              'assistant_turn',           'SET NULL',  TRUE),
+      ('assistant_usage',          'provider_id',          'assistant_provider',       'NO ACTION', TRUE),
+      ('assistant_data_audit',     'provider_id',          'assistant_provider',       'NO ACTION', TRUE),
+      ('assistant_budget_usage',   'provider_id',          'assistant_provider',       'NO ACTION', TRUE),
+      ('assistant_profile_skill',  'profile_id',           'assistant_profile',        'CASCADE',   FALSE),
+      ('assistant_profile_skill',  'skill_id',             'assistant_skill',          'CASCADE',   FALSE)
+   ) AS v(child, col, parent, rule, nullable)
+   LOOP
+      IF NOT EXISTS (SELECT 1 FROM information_schema.table_constraints WHERE constraint_schema = current_schema() AND LOWER(constraint_name) = 'fk_' || r.child || '_' || r.col) THEN
+         IF r.nullable THEN
+            EXECUTE format('INSERT INTO qqq_fk_quarantine (table_name, column_name, row_id, missing_parent_id, action, changeset) '
+               || 'SELECT %L, %L, c.id::text, c.%I::text, ''NULLED'', ''qbit-assistant 2026-10-14 foreign keys'' FROM %I c '
+               || 'WHERE c.%I IS NOT NULL AND NOT EXISTS (SELECT 1 FROM %I p WHERE p.id = c.%I)', r.child, r.col, r.col, r.child, r.col, r.parent, r.col);
+            EXECUTE format('UPDATE %I c SET %I = NULL WHERE c.%I IS NOT NULL AND NOT EXISTS (SELECT 1 FROM %I p WHERE p.id = c.%I)', r.child, r.col, r.col, r.parent, r.col);
+         ELSE
+            EXECUTE format('INSERT INTO qqq_fk_quarantine (table_name, column_name, row_id, missing_parent_id, action, row_data, changeset) '
+               || 'SELECT %L, %L, c.id::text, c.%I::text, ''DELETED'', row_to_json(c)::text, ''qbit-assistant 2026-10-14 foreign keys'' FROM %I c '
+               || 'WHERE NOT EXISTS (SELECT 1 FROM %I p WHERE p.id = c.%I)', r.child, r.col, r.col, r.child, r.parent, r.col);
+            EXECUTE format('DELETE FROM %I c WHERE NOT EXISTS (SELECT 1 FROM %I p WHERE p.id = c.%I)', r.child, r.parent, r.col);
+         END IF;
+         EXECUTE format('ALTER TABLE %I ADD CONSTRAINT %I FOREIGN KEY (%I) REFERENCES %I (id) ON DELETE %s', r.child, 'fk_' || r.child || '_' || r.col, r.col, r.parent, r.rule);
+      END IF;
+   END LOOP;
+
+   -- assistant_model.provider_id: the inline NO ACTION key becomes CASCADE, named as on kof22.
+   IF NOT EXISTS (SELECT 1 FROM information_schema.table_constraints WHERE constraint_schema = current_schema() AND LOWER(constraint_name) = 'fk_assistant_model_provider') THEN
+      FOR old IN SELECT conname FROM pg_constraint
+         WHERE contype = 'f' AND conrelid = 'assistant_model'::regclass AND confrelid = 'assistant_provider'::regclass
+      LOOP
+         EXECUTE format('ALTER TABLE assistant_model DROP CONSTRAINT %I', old);
+      END LOOP;
+      ALTER TABLE assistant_model ADD CONSTRAINT fk_assistant_model_provider FOREIGN KEY (provider_id) REFERENCES assistant_provider (id) ON DELETE CASCADE;
+   END IF;
+END $$;

qbit-assistant/pom.xml

@@ -87,6 +87,25 @@
          <version>4.33.0</version>
          <scope>test</scope>
       </dependency>
+      <!-- the reference DDL guardrail (SchemaForeignKeyPostgresTest) -->
+      <dependency>
+         <groupId>org.testcontainers</groupId>
+         <artifactId>junit-jupiter</artifactId>
+         <version>1.21.4</version>
+         <scope>test</scope>
+      </dependency>
+      <dependency>
+         <groupId>org.testcontainers</groupId>
+         <artifactId>postgresql</artifactId>
+         <version>1.21.4</version>
+         <scope>test</scope>
+      </dependency>
+      <dependency>
+         <groupId>org.postgresql</groupId>
+         <artifactId>postgresql</artifactId>
+         <version>42.7.14</version>
+         <scope>test</scope>
+      </dependency>
    </dependencies>
 
    <build>

qbit-assistant/src/main/java/com/kingsrook/qbits/assistant/AssistantQBitConfig.java

@@ -17,6 +17,7 @@
 package com.kingsrook.qbits.assistant;
 
 
+import javax.net.ssl.SSLContext;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -31,6 +32,7 @@ import java.util.regex.Pattern;
 import com.fasterxml.jackson.annotation.JsonIgnore;
 import com.kingsrook.qbits.assistant.classification.ClassificationSource;
 import com.kingsrook.qbits.assistant.classification.ConfiguredClassificationSource;
+import com.kingsrook.qbits.assistant.jobs.AssistantRunTracker;
 import com.kingsrook.qbits.assistant.rag.VectorStore;
 import com.kingsrook.qbits.assistant.spi.AssistantModelProvider;
 import com.kingsrook.qbits.assistant.spi.AssistantProviderType;
@@ -44,7 +46,6 @@ import com.kingsrook.qqq.backend.core.model.metadata.producers.MetaDataCustomize
 import com.kingsrook.qqq.backend.core.model.metadata.qbits.QBitConfig;
 import com.kingsrook.qqq.backend.core.model.metadata.tables.QTableMetaData;
 import com.kingsrook.qqq.backend.core.utils.StringUtils;
-import javax.net.ssl.SSLContext;
 
 
 /*******************************************************************************
@@ -99,12 +100,20 @@ public class AssistantQBitConfig implements QBitConfig
    private Integer               maxParallelToolCalls       = 4;
    private Integer               maxRowsToModel             = 50;
    private Integer               maxCellChars               = 500;
+   private Integer turnHeartbeatSeconds = 5;
+   private Integer turnLeaseSeconds = 45;
+   private Integer turnForceFinalizeGraceSeconds = 20;
+   private Integer shutdownGraceSeconds = 8;
+   private String defaultConcurrencyMode = "SUPERSEDE";
+   private Boolean registerShutdownHook = true;
+   private AssistantRunTracker runTracker = AssistantRunTracker.NOOP;
+
    private Integer               maxTurnSeconds             = 300;
    private Integer               maxUserMessageChars        = 8000;
    private Integer               historyMessageLimit        = 40;
    private AssistantBudgets      budgets                    = new AssistantBudgets();
    private Integer               maxTurnsPerUserPerMinute   = 10;
-   private Integer               maxConcurrentTurnsPerUser  = 1;
+   private Integer               maxConcurrentTurnsPerUser  = 3;
    private Integer               conversationRetentionDays  = 90;
    private Integer               toolResultRetentionDays    = 30;
    private Integer               approvalRetentionDays      = 365;
@@ -206,6 +215,23 @@ public class AssistantQBitConfig implements QBitConfig
       requirePositive(errors, "maxRowsToModel", maxRowsToModel);
       requirePositive(errors, "maxCellChars", maxCellChars);
       requirePositive(errors, "maxTurnSeconds", maxTurnSeconds);
+      requirePositive(errors, "turnHeartbeatSeconds", turnHeartbeatSeconds);
+      requirePositive(errors, "turnLeaseSeconds", turnLeaseSeconds);
+      requirePositive(errors, "turnForceFinalizeGraceSeconds", turnForceFinalizeGraceSeconds);
+      requirePositive(errors, "shutdownGraceSeconds", shutdownGraceSeconds);
+      if(turnHeartbeatSeconds != null && turnLeaseSeconds != null && turnLeaseSeconds < 2 * turnHeartbeatSeconds)
+      {
+         errors.add("turnLeaseSeconds must be at least twice turnHeartbeatSeconds.");
+      }
+      if(!"SUPERSEDE".equals(defaultConcurrencyMode) && !"CONCURRENT".equals(defaultConcurrencyMode))
+      {
+         errors.add("defaultConcurrencyMode must be SUPERSEDE or CONCURRENT.");
+      }
+      if(turnHeartbeatSeconds != null && turnLeaseSeconds != null && turnHeartbeatSeconds >= turnLeaseSeconds)
+      {
+         errors.add("turnHeartbeatSeconds must be less than turnLeaseSeconds.");
+      }
+
       requirePositive(errors, "maxUserMessageChars", maxUserMessageChars);
       requirePositive(errors, "historyMessageLimit", historyMessageLimit);
       requirePositive(errors, "maxTurnsPerUserPerMinute", maxTurnsPerUserPerMinute);
@@ -2008,4 +2034,223 @@ public class AssistantQBitConfig implements QBitConfig
       this.scheduledTasksSchedulerName = scheduledTasksSchedulerName;
       return (this);
    }
+
+
+
+   /*******************************************************************************
+    ** Getter for turnHeartbeatSeconds
+    *******************************************************************************/
+   public Integer getTurnHeartbeatSeconds()
+   {
+      return (this.turnHeartbeatSeconds);
+   }
+
+
+
+   /*******************************************************************************
+    ** Setter for turnHeartbeatSeconds
+    *******************************************************************************/
+   public void setTurnHeartbeatSeconds(Integer turnHeartbeatSeconds)
+   {
+      this.turnHeartbeatSeconds = turnHeartbeatSeconds;
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for turnHeartbeatSeconds
+    *******************************************************************************/
+   public AssistantQBitConfig withTurnHeartbeatSeconds(Integer turnHeartbeatSeconds)
+   {
+      this.turnHeartbeatSeconds = turnHeartbeatSeconds;
+      return (this);
+   }
+
+
+
+   /*******************************************************************************
+    ** Getter for turnLeaseSeconds
+    *******************************************************************************/
+   public Integer getTurnLeaseSeconds()
+   {
+      return (this.turnLeaseSeconds);
+   }
+
+
+
+   /*******************************************************************************
+    ** Setter for turnLeaseSeconds
+    *******************************************************************************/
+   public void setTurnLeaseSeconds(Integer turnLeaseSeconds)
+   {
+      this.turnLeaseSeconds = turnLeaseSeconds;
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for turnLeaseSeconds
+    *******************************************************************************/
+   public AssistantQBitConfig withTurnLeaseSeconds(Integer turnLeaseSeconds)
+   {
+      this.turnLeaseSeconds = turnLeaseSeconds;
+      return (this);
+   }
+
+
+
+   /*******************************************************************************
+    ** Getter for turnForceFinalizeGraceSeconds
+    *******************************************************************************/
+   public Integer getTurnForceFinalizeGraceSeconds()
+   {
+      return (this.turnForceFinalizeGraceSeconds);
+   }
+
+
+
+   /*******************************************************************************
+    ** Setter for turnForceFinalizeGraceSeconds
+    *******************************************************************************/
+   public void setTurnForceFinalizeGraceSeconds(Integer turnForceFinalizeGraceSeconds)
+   {
+      this.turnForceFinalizeGraceSeconds = turnForceFinalizeGraceSeconds;
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for turnForceFinalizeGraceSeconds
+    *******************************************************************************/
+   public AssistantQBitConfig withTurnForceFinalizeGraceSeconds(Integer turnForceFinalizeGraceSeconds)
+   {
+      this.turnForceFinalizeGraceSeconds = turnForceFinalizeGraceSeconds;
+      return (this);
+   }
+
+
+
+   /*******************************************************************************
+    ** Getter for shutdownGraceSeconds
+    *******************************************************************************/
+   public Integer getShutdownGraceSeconds()
+   {
+      return (this.shutdownGraceSeconds);
+   }
+
+
+
+   /*******************************************************************************
+    ** Setter for shutdownGraceSeconds
+    *******************************************************************************/
+   public void setShutdownGraceSeconds(Integer shutdownGraceSeconds)
+   {
+      this.shutdownGraceSeconds = shutdownGraceSeconds;
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for shutdownGraceSeconds
+    *******************************************************************************/
+   public AssistantQBitConfig withShutdownGraceSeconds(Integer shutdownGraceSeconds)
+   {
+      this.shutdownGraceSeconds = shutdownGraceSeconds;
+      return (this);
+   }
+
+
+
+   /*******************************************************************************
+    ** Getter for defaultConcurrencyMode
+    *******************************************************************************/
+   public String getDefaultConcurrencyMode()
+   {
+      return (this.defaultConcurrencyMode);
+   }
+
+
+
+   /*******************************************************************************
+    ** Setter for defaultConcurrencyMode
+    *******************************************************************************/
+   public void setDefaultConcurrencyMode(String defaultConcurrencyMode)
+   {
+      this.defaultConcurrencyMode = defaultConcurrencyMode;
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for defaultConcurrencyMode
+    *******************************************************************************/
+   public AssistantQBitConfig withDefaultConcurrencyMode(String defaultConcurrencyMode)
+   {
+      this.defaultConcurrencyMode = defaultConcurrencyMode;
+      return (this);
+   }
+
+
+
+   /*******************************************************************************
+    ** Getter for registerShutdownHook
+    *******************************************************************************/
+   public Boolean getRegisterShutdownHook()
+   {
+      return (this.registerShutdownHook);
+   }
+
+
+
+   /*******************************************************************************
+    ** Setter for registerShutdownHook
+    *******************************************************************************/
+   public void setRegisterShutdownHook(Boolean registerShutdownHook)
+   {
+      this.registerShutdownHook = registerShutdownHook;
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for registerShutdownHook
+    *******************************************************************************/
+   public AssistantQBitConfig withRegisterShutdownHook(Boolean registerShutdownHook)
+   {
+      this.registerShutdownHook = registerShutdownHook;
+      return (this);
+   }
+
+
+
+   /*******************************************************************************
+    ** Getter for runTracker
+    *******************************************************************************/
+   @JsonIgnore
+   public AssistantRunTracker getRunTracker()
+   {
+      return (this.runTracker == null ? AssistantRunTracker.NOOP : this.runTracker);
+   }
+
+
+
+   /*******************************************************************************
+    ** Setter for runTracker
+    *******************************************************************************/
+   public void setRunTracker(AssistantRunTracker runTracker)
+   {
+      this.runTracker = runTracker;
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for runTracker
+    *******************************************************************************/
+   public AssistantQBitConfig withRunTracker(AssistantRunTracker runTracker)
+   {
+      this.runTracker = runTracker;
+      return (this);
+   }
+
 }

qbit-assistant/src/main/java/com/kingsrook/qbits/assistant/AssistantRuntime.java

@@ -17,8 +17,11 @@
 package com.kingsrook.qbits.assistant;
 
 
+import java.net.InetAddress;
 import java.time.Clock;
+import java.time.Duration;
 import java.util.Map;
+import java.util.UUID;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
@@ -50,6 +53,7 @@ import com.kingsrook.qqq.backend.core.actions.ai.AiToolKernelSettings;
 import com.kingsrook.qqq.backend.core.actions.ai.exposure.AiExposurePolicy;
 import com.kingsrook.qqq.backend.core.actions.ai.output.AiRedactor;
 import com.kingsrook.qqq.backend.core.exceptions.QException;
+import com.kingsrook.qqq.backend.core.logging.QLogger;
 import com.kingsrook.qqq.backend.core.model.metadata.QInstance;
 import com.kingsrook.qqq.backend.core.model.metadata.qbits.QBitMetaData;
 import com.kingsrook.qqq.backend.core.utils.StringUtils;
@@ -62,6 +66,11 @@ import com.kingsrook.qqq.backend.core.utils.StringUtils;
  *******************************************************************************/
 public class AssistantRuntime
 {
+   private static final QLogger LOG = QLogger.getLogger(AssistantRuntime.class);
+   private final String instanceId = instanceId();
+   private volatile boolean shuttingDown;
+   private Thread shutdownHook;
+
    private final ScheduledTurn scheduledTurn = new ScheduledTurn();
 
    private final RagService ragService;
@@ -103,12 +112,22 @@ public class AssistantRuntime
     **
     *******************************************************************************/
    public AssistantRuntime(QInstance qInstance, AssistantQBitConfig config, Clock clock)
+   {
+      this(qInstance, config, clock, new AssistantStore(config));
+   }
+
+
+
+   /*******************************************************************************
+    ** Explicit persistence collaborator for embedded runtimes and fault tests.
+    *******************************************************************************/
+   public AssistantRuntime(QInstance qInstance, AssistantQBitConfig config, Clock clock, AssistantStore store)
    {
       AssistantChannelWall.validate(qInstance);
       this.qInstance = qInstance;
       this.config = config;
       this.clock = clock;
-      this.store = new AssistantStore(config);
+      this.store = store;
       this.policyService = new PolicyService(config, store, clock);
       this.providerService = new ProviderService(config, store, clock);
       this.budgetService = new BudgetService(store, providerService, clock);
@@ -157,6 +176,21 @@ public class AssistantRuntime
       this.knowledgeTool = new KnowledgeTool(this, ragService, vectors);
       this.bulkLoadTools = new BulkLoadTools(qInstance, dataAccessService, config.getBulkLoadRunner());
       this.contextBuilder = new ContextBuilder(config, kernel, toolbox).withKnowledgeTool(knowledgeTool).withBulkLoadTools(bulkLoadTools);
+      if(Boolean.TRUE.equals(config.getRegisterShutdownHook()))
+      {
+         shutdownHook = new Thread(() ->
+         {
+            try
+            {
+               shutdown(Duration.ofSeconds(config.getShutdownGraceSeconds()));
+            }
+            catch(Throwable ignored)
+            {
+               // Shutdown must never fail the JVM hook.
+            }
+         }, "assistant-shutdown-" + instanceId);
+         Runtime.getRuntime().addShutdownHook(shutdownHook);
+      }
    }
 
 
@@ -312,8 +346,13 @@ public class AssistantRuntime
    /*******************************************************************************
     ** Track a turn running here.
     *******************************************************************************/
-   public RunningTurn register(RunningTurn turn)
+   public synchronized RunningTurn register(RunningTurn turn)
    {
+      if(shuttingDown)
+      {
+         turn.forceFinalize("SHUTDOWN");
+         return (turn);
+      }
       runningTurns.put(turn.getTurnId(), turn);
       return (turn);
    }
@@ -345,7 +384,17 @@ public class AssistantRuntime
     *******************************************************************************/
    public void cancelAll(String reason)
    {
-      runningTurns.values().forEach(t -> t.cancel(reason));
+      runningTurns.values().forEach(t ->
+      {
+         try
+         {
+            t.cancel(reason);
+         }
+         catch(Exception e)
+         {
+            LOG.warn("Assistant cancellation failed; finalization will still run");
+         }
+      });
    }
 
 
@@ -355,8 +404,7 @@ public class AssistantRuntime
     *******************************************************************************/
    public void close()
    {
-      runningTurns.values().forEach(t -> t.cancel("SHUTDOWN"));
-      executor.shutdownNow();
+      shutdown(Duration.ZERO);
    }
 
 
@@ -504,4 +552,97 @@ public class AssistantRuntime
       return (bulkLoadTools);
    }
 
+
+
+
+   /*******************************************************************************
+    ** Stop accepting work, cancel, wait a bounded grace, then force finalization.
+    *******************************************************************************/
+   public void shutdown(Duration grace)
+   {
+      synchronized(this)
+      {
+         shuttingDown = true;
+      }
+      cancelAll("SHUTDOWN");
+      long until = System.nanoTime() + Math.max(0, grace.toNanos());
+      while(!runningTurns.isEmpty() && System.nanoTime() < until)
+      {
+         try
+         {
+            Thread.sleep(10);
+         }
+         catch(InterruptedException e)
+         {
+            Thread.currentThread().interrupt();
+            break;
+         }
+      }
+      runningTurns.values().forEach(t ->
+      {
+         try
+         {
+            t.forceFinalize("SHUTDOWN");
+         }
+         catch(Exception e)
+         {
+            LOG.warn("Assistant shutdown finalization failed");
+         }
+      });
+      executor.shutdownNow();
+      if(shutdownHook != null && Thread.currentThread() != shutdownHook)
+      {
+         try
+         {
+            Runtime.getRuntime().removeShutdownHook(shutdownHook);
+         }
+         catch(IllegalStateException ignored)
+         {
+            // The JVM is already shutting down.
+         }
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** Getter for shuttingDown
+    *******************************************************************************/
+   public boolean isShuttingDown()
+   {
+      return (shuttingDown);
+   }
+
+
+
+   /*******************************************************************************
+    ** Getter for instanceId
+    *******************************************************************************/
+   public String getInstanceId()
+   {
+      return (instanceId);
+   }
+
+
+
+   /*******************************************************************************
+    ** A stable, bounded hostname plus a per-runtime random suffix.
+    *******************************************************************************/
+   private static String instanceId()
+   {
+      String host = System.getenv("HOSTNAME");
+      if(!StringUtils.hasContent(host))
+      {
+         try
+         {
+            host = InetAddress.getLocalHost().getHostName();
+         }
+         catch(Exception ignored)
+         {
+            host = "unknown";
+         }
+      }
+      return (host.substring(0, Math.min(87, host.length())) + ":" + UUID.randomUUID().toString().substring(0, 8));
+   }
+
 }

qbit-assistant/src/main/java/com/kingsrook/qbits/assistant/api/AssistantApi.java

@@ -17,11 +17,14 @@
 package com.kingsrook.qbits.assistant.api;
 
 
+import java.time.Duration;
 import java.time.Instant;
 import java.util.ArrayList;
+import java.util.Comparator;
 import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Locale;
 import java.util.Map;
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.kingsrook.qbits.assistant.AssistantQBitConfig;
@@ -51,11 +54,13 @@ import com.kingsrook.qqq.backend.core.actions.ai.AiToolOutcome;
 import com.kingsrook.qqq.backend.core.actions.ai.AiToolResult;
 import com.kingsrook.qqq.backend.core.actions.ai.output.AiRedactor;
 import com.kingsrook.qqq.backend.core.exceptions.QException;
+import com.kingsrook.qqq.backend.core.logging.QLogger;
 import com.kingsrook.qqq.backend.core.model.data.QRecord;
 import com.kingsrook.qqq.backend.core.model.session.QSession;
 import com.kingsrook.qqq.backend.core.utils.JsonUtils;
 import com.kingsrook.qqq.backend.core.utils.StringUtils;
 import com.kingsrook.qqq.middleware.javalin.specs.invoke.UiApiCredentials;
+import static com.kingsrook.qqq.backend.core.logging.LogUtils.logPair;
 
 
 /*******************************************************************************
@@ -65,6 +70,8 @@ import com.kingsrook.qqq.middleware.javalin.specs.invoke.UiApiCredentials;
  *******************************************************************************/
 public class AssistantApi
 {
+   private static final QLogger LOG = QLogger.getLogger(AssistantApi.class);
+
    public static final int TITLE_MAX_CHARS = 60;
 
    private final AssistantRuntime    runtime;
@@ -289,6 +296,19 @@ public class AssistantApi
    public RunningTurn startTurn(Integer conversationId, Map<String, Object> body) throws QException, AssistantApiException
    {
       requireAccess();
+      if(runtime.isShuttingDown())
+      {
+         throw (new AssistantApiException(503, "SHUTTING_DOWN", "The server is restarting. Try again in a moment."));
+      }
+      String concurrency = config.getDefaultConcurrencyMode();
+      if(body.containsKey("concurrency"))
+      {
+         if(!(body.get("concurrency") instanceof String mode) || !("supersede".equalsIgnoreCase(mode) || "concurrent".equalsIgnoreCase(mode)))
+         {
+            throw (new AssistantApiException(400, "concurrency must be supersede or concurrent."));
+         }
+         concurrency = mode.toUpperCase(Locale.ROOT);
+      }
       AssistantConversation conversation = requireConversation(conversationId);
 
       if(!(body.get("text") instanceof String text) || !StringUtils.hasContent(text))
@@ -324,25 +344,36 @@ public class AssistantApi
          throw (new AssistantApiException(429, "BUDGET", budget.message()));
       }
 
-      long running = 0;
-      for(AssistantTurn other : store.listRunningTurns(userId))
-      {
-         if(isRunning(reapIfOrphaned(other)))
-         {
-            running++;
-         }
-      }
-      if(running >= config.getMaxConcurrentTurnsPerUser())
-      {
-         throw (new AssistantApiException(429, "RATE_LIMIT", "You already have an assistant answer in progress. Wait for it to finish or stop it."));
-      }
-
       String limited = runtime.getRateLimiter().tryAcquire(userId, config.getMaxTurnsPerUserPerMinute(), config.getMaxConcurrentTurnsPerUser());
       if(limited != null)
       {
          throw (new AssistantApiException(429, "RATE_LIMIT", limited));
       }
 
+      List<AssistantTurn> remaining = new ArrayList<>();
+      for(AssistantTurn other : store.listRunningTurns(userId))
+      {
+         other = reapIfOrphaned(other);
+         if(!isRunning(other) || "SUPERSEDED".equals(other.getCancelReason()))
+         {
+            continue;
+         }
+         if("SUPERSEDE".equals(concurrency) && conversationId.equals(other.getConversationId()))
+         {
+            requestStop(other, "SUPERSEDED");
+         }
+         else
+         {
+            remaining.add(other);
+         }
+      }
+      remaining.sort(Comparator.comparing(AssistantTurn::getStartedAt, Comparator.nullsFirst(Comparator.naturalOrder()))
+         .thenComparing(AssistantTurn::getId));
+      while(remaining.size() >= config.getMaxConcurrentTurnsPerUser())
+      {
+         requestStop(remaining.removeFirst(), "SUPERSEDED");
+      }
+
       try
       {
          if(!StringUtils.hasContent(conversation.getTitle()))
@@ -361,13 +392,18 @@ public class AssistantApi
             .withSeq(seq)
             .withPartsJson(new MessageParts().addText(text).toJson()));
 
+         Instant startedAt = runtime.getClock().instant();
          AssistantTurn turn = store.insert(new AssistantTurn()
             .withConversationId(conversationId)
             .withUserId(userId)
             .withUserMessageId(userMessage.getId())
             .withStatus("RUNNING")
             .withModel(active.model())
-            .withStartedAt(runtime.getClock().instant())
+            .withStartedAt(startedAt)
+            .withHeartbeatAt(startedAt)
+            .withLeaseOwner(runtime.getInstanceId())
+            .withPhase("starting")
+            .withConcurrencyMode(concurrency)
             .withToolCallCount(0)
             .withModelCallCount(0));
 
@@ -385,10 +421,37 @@ public class AssistantApi
          store.updateFields(AssistantTurn.TABLE_NAME, new QRecord().withValue("id", turn.getId()).withValue("assistantMessageId", assistantMessage.getId()));
          turn.setAssistantMessageId(assistantMessage.getId());
 
-         RunningTurn runningTurn = runtime.register(new RunningTurn(turn.getId(), userId));
+         RunningTurn runningTurn = new RunningTurn(turn.getId(), userId);
          TurnEngine  engine      = new TurnEngine(runtime, session, userId, conversation, userMessage, assistantMessage, turn, text, pageContext, policy, runningTurn,
             budget.softExceeded() ? budget.message() : null).withCredentials(credentials);
-         runtime.getExecutor().submit(engine);
+         try
+         {
+            if(config.getRunTracker() != null)
+            {
+               ///////////////////////////////////////////////////////////////////
+               // never the conversation title: it is derived from the prompt  //
+               ///////////////////////////////////////////////////////////////////
+               runningTurn.setTrackingId(config.getRunTracker().start(userId, turn.getId(), conversationId, "Assistant answer"));
+               config.getRunTracker().onCancel(runningTurn.getTrackingId(), () -> runningTurn.cancel("USER"));
+            }
+         }
+         catch(Exception e)
+         {
+            LOG.warn("Assistant run tracker start failed", logPair("turnId", turn.getId()));
+         }
+         runtime.register(runningTurn);
+         if(!runningTurn.isFinalized())
+         {
+            try
+            {
+               runtime.getExecutor().submit(engine);
+            }
+            catch(RuntimeException e)
+            {
+               runningTurn.forceFinalize("SHUTDOWN");
+               throw (e);
+            }
+         }
          return (runningTurn);
       }
       catch(QException | RuntimeException e)
@@ -443,22 +506,94 @@ public class AssistantApi
    {
       requireAccess();
       AssistantTurn turn = requireTurn(turnId);
-      if(runtime.getRunningTurn(turnId) == null)
+      if(isRunning(turn))
+      {
+         turn = requestStop(turn, "USER");
+      }
+      return (Map.of("status", turn.getStatus()));
+   }
+
+
+
+   /*******************************************************************************
+    ** Durable Stop, shared by the API and superseding another question.
+    *******************************************************************************/
+   private AssistantTurn requestStop(AssistantTurn turn, String reason) throws QException
+   {
+      synchronized(store)
+      {
+         turn = store.getTurn(userId, turn.getId());
+         if(!isRunning(turn))
+         {
+            return (turn);
+         }
+         RunningTurn live = runtime.getRunningTurn(turn.getId());
+         if(live == null && orphaned(turn))
+         {
+            return (reap(turn, reason));
+         }
+         Instant now = runtime.getClock().instant();
+         if(!store.updateRunningTurn(userId, new QRecord().withValue("id", turn.getId())
+            .withValue("status", "CANCELLING").withValue("cancelReason", reason).withValue("cancelRequestedAt", now)))
+         {
+            return (store.getTurn(userId, turn.getId()));
+         }
+         turn.setStatus("CANCELLING");
+         turn.setCancelReason(reason);
+         turn.setCancelRequestedAt(now);
+         if(live != null)
+         {
+            try
+            {
+               live.cancel(reason);
+            }
+            catch(Exception e)
+            {
+               LOG.warn("Assistant stream cancellation failed; watchdog will finalize");
+            }
+         }
+         return (turn);
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** GET /turns/active: the caller's runs, newest first, after orphan recovery.
+    *******************************************************************************/
+   public Map<String, Object> activeTurns() throws QException, AssistantApiException
+   {
+      requireAccess();
+      List<AssistantTurn> turns = new ArrayList<>();
+      for(AssistantTurn turn : store.listRunningTurns(userId))
       {
          turn = reapIfOrphaned(turn);
+         if(isRunning(turn))
+         {
+            turns.add(turn);
+         }
       }
-      if(!isRunning(turn))
+      turns.sort(Comparator.comparing(AssistantTurn::getStartedAt, Comparator.nullsFirst(Comparator.naturalOrder()))
+         .thenComparing(AssistantTurn::getId).reversed());
+      List<Map<String, Object>> rows = new ArrayList<>();
+      for(AssistantTurn turn : turns)
       {
-         throw (new AssistantApiException(409, "This answer has already finished."));
+         RunningTurn live = runtime.getRunningTurn(turn.getId());
+         Map<String, Object> row = new LinkedHashMap<>();
+         row.put("turnId", turn.getId());
+         row.put("conversationId", turn.getConversationId());
+         row.put("assistantMessageId", turn.getAssistantMessageId());
+         row.put("userMessageId", turn.getUserMessageId());
+         row.put("status", turn.getStatus());
+         row.put("phase", live == null ? turn.getPhase() : live.getPhase());
+         row.put("startedAt", turn.getStartedAt() == null ? null : turn.getStartedAt().toString());
+         row.put("heartbeatAt", turn.getHeartbeatAt() == null ? null : turn.getHeartbeatAt().toString());
+         row.put("elapsedMs", turn.getStartedAt() == null ? 0 : Math.max(0, Duration.between(turn.getStartedAt(), runtime.getClock().instant()).toMillis()));
+         row.put("live", live != null);
+         row.put("concurrencyMode", turn.getConcurrencyMode());
+         rows.add(row);
       }
-
-      store.updateFields(AssistantTurn.TABLE_NAME, new QRecord().withValue("id", turnId).withValue("status", "CANCELLING"));
-      RunningTurn live = runtime.getRunningTurn(turnId);
-      if(live != null && userId.equals(live.getUserId()))
-      {
-         live.cancel("USER");
-      }
-      return (Map.of("status", "CANCELLING"));
+      return (Map.of("turns", rows));
    }
 
 
@@ -474,60 +609,104 @@ public class AssistantApi
 
 
    /*******************************************************************************
-    ** A turn whose replica died: it still says RUNNING / CANCELLING, no turn
-    ** of this runtime owns it, and it started longer ago than maxTurnSeconds
-    ** + 60 s (a live engine always ends itself by then). On first sight it is
-    ** finished as ERROR: the assistant message gets status ERROR and a
-    ** notice, and synthetic error (INTERNAL) + message.end events are
-    ** persisted, so replays end. Returns the (possibly updated) turn.
+    ** A remote run loses its lease, exceeds the absolute deadline, or has a
+    ** cancellation request that its owner did not acknowledge in time.
+    *******************************************************************************/
+   private boolean orphaned(AssistantTurn turn)
+   {
+      Instant now = runtime.getClock().instant();
+      Instant heartbeat = turn.getHeartbeatAt() == null ? turn.getStartedAt() : turn.getHeartbeatAt();
+      return ((heartbeat != null && heartbeat.isBefore(now.minusSeconds(config.getTurnLeaseSeconds())))
+         || (turn.getStartedAt() != null && turn.getStartedAt().isBefore(now.minusSeconds(maxStreamSeconds())))
+         || ("CANCELLING".equals(turn.getStatus()) && turn.getCancelRequestedAt() != null
+         && turn.getCancelRequestedAt().isBefore(now.minusSeconds(config.getTurnLeaseSeconds()))));
+   }
+
+
+
+   /*******************************************************************************
+    ** Recover an abandoned run and leave a terminal replay for refreshes.
     *******************************************************************************/
    AssistantTurn reapIfOrphaned(AssistantTurn turn) throws QException
    {
-      if(!isRunning(turn) || runtime.getRunningTurn(turn.getId()) != null || turn.getStartedAt() == null)
+      synchronized(store)
       {
-         return (turn);
-      }
-      Instant stale = runtime.getClock().instant().minusSeconds(config.getMaxTurnSeconds() + 60L);
-      if(!turn.getStartedAt().isBefore(stale))
-      {
-         return (turn);
-      }
-
-      String text = "This answer was interrupted (the server restarted). Ask again.";
-      if(turn.getAssistantMessageId() != null)
-      {
-         AssistantMessage message = store.getMessage(userId, turn.getAssistantMessageId());
-         if(message != null)
+         if(!isRunning(turn) || runtime.getRunningTurn(turn.getId()) != null || !orphaned(turn))
          {
-            store.updateFields(AssistantMessage.TABLE_NAME, new QRecord()
-               .withValue("id", message.getId())
-               .withValue("status", "ERROR")
-               .withValue("partsJson", MessageParts.fromJson(message.getPartsJson()).addNotice("error", text).toJson()));
+            return (turn);
+         }
+         String reason = "CANCELLING".equals(turn.getStatus()) && turn.getCancelRequestedAt() != null
+            && turn.getCancelRequestedAt().isBefore(runtime.getClock().instant().minusSeconds(config.getTurnLeaseSeconds()))
+            ? (turn.getCancelReason() == null ? "USER" : turn.getCancelReason()) : null;
+         return (reap(turn, reason));
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** Re-read before recovery; never overwrite an already terminal row or
+    ** append another terminal event. Each persistence step is independent.
+    *******************************************************************************/
+   private AssistantTurn reap(AssistantTurn turn, String cancelReason) throws QException
+   {
+      AssistantTurn current = store.getTurn(userId, turn.getId());
+      if(!isRunning(current))
+      {
+         return (current);
+      }
+      if(!orphaned(current))
+      {
+         return (cancelReason == null ? current : requestStop(current, cancelReason));
+      }
+      String status = cancelReason == null ? "ERROR" : "CANCELLED";
+      String text = cancelReason == null ? "This answer was interrupted (the server restarted). Ask again."
+         : ("SUPERSEDED".equals(cancelReason) ? TurnEngine.SUPERSEDED_TEXT : "Stopped by you.");
+      if(current.getAssistantMessageId() != null)
+      {
+         try
+         {
+            AssistantMessage message = store.getMessage(userId, current.getAssistantMessageId());
+            if(message != null)
+            {
+               store.updateFields(AssistantMessage.TABLE_NAME, new QRecord().withValue("id", message.getId()).withValue("status", status)
+                  .withValue("partsJson", MessageParts.fromJson(message.getPartsJson()).addNotice(cancelReason == null ? "error" : "info", text).toJson()));
+            }
+         }
+         catch(Exception e)
+         {
+            LOG.warn("Could not persist recovered assistant message");
          }
       }
-
-      int seq = store.lastEventSeq(userId, turn.getId());
-      store.insertEvent(turn.getId(), userId, seq + 1, TurnEvent.ERROR, new TurnEvent(seq + 1, TurnEvent.ERROR, Map.of("code", "INTERNAL", "message", text)).toJson());
-      Map<String, Object> end = new java.util.LinkedHashMap<>();
-      if(turn.getAssistantMessageId() != null)
+      try
       {
-         end.put("messageId", turn.getAssistantMessageId());
+         int seq = store.lastEventSeq(userId, current.getId());
+         List<AssistantTurnEvent> last = store.listEvents(userId, current.getId(), Math.max(0, seq - 1), 1);
+         if(last.isEmpty() || !TurnEvent.MESSAGE_END.equals(last.getFirst().getEventType()))
+         {
+            if(cancelReason == null)
+            {
+               seq++;
+               store.insertEvent(current.getId(), userId, seq, TurnEvent.ERROR,
+                  new TurnEvent(seq, TurnEvent.ERROR, Map.of("code", "INTERNAL", "message", text)).toJson());
+            }
+            seq++;
+            Map<String, Object> end = new LinkedHashMap<>();
+            end.put("messageId", current.getAssistantMessageId());
+            end.put("status", status);
+            end.put("stopReason", cancelReason == null ? "interrupted" : "cancelled");
+            store.insertEvent(current.getId(), userId, seq, TurnEvent.MESSAGE_END, new TurnEvent(seq, TurnEvent.MESSAGE_END, end).toJson());
+         }
+      }
+      catch(Exception e)
+      {
+         LOG.warn("Could not persist recovered assistant events");
       }
-      end.put("status", "ERROR");
-      end.put("stopReason", "interrupted");
-      store.insertEvent(turn.getId(), userId, seq + 2, TurnEvent.MESSAGE_END, new TurnEvent(seq + 2, TurnEvent.MESSAGE_END, end).toJson());
-
       Instant now = runtime.getClock().instant();
-      store.updateFields(AssistantTurn.TABLE_NAME, new QRecord()
-         .withValue("id", turn.getId())
-         .withValue("status", "ERROR")
-         .withValue("errorCode", "INTERNAL")
-         .withValue("stopReason", "interrupted")
-         .withValue("endedAt", now));
-      turn.setStatus("ERROR");
-      turn.setErrorCode("INTERNAL");
-      turn.setEndedAt(now);
-      return (turn);
+      store.updateRunningTurn(userId, new QRecord().withValue("id", current.getId()).withValue("status", status)
+         .withValue("errorCode", cancelReason == null ? "INTERNAL" : null).withValue("cancelReason", cancelReason)
+         .withValue("stopReason", cancelReason == null ? "interrupted" : "cancelled").withValue("phase", "done").withValue("endedAt", now));
+      return (store.getTurn(userId, current.getId()));
    }
 
 
@@ -786,6 +965,16 @@ public class AssistantApi
 
 
 
+   /*******************************************************************************
+    ** Hard upper bound for remote stream polling and stale-run recovery.
+    *******************************************************************************/
+   public long maxStreamSeconds()
+   {
+      return (config.getMaxTurnSeconds() + (long) config.getTurnForceFinalizeGraceSeconds() + config.getTurnLeaseSeconds());
+   }
+
+
+
    /*******************************************************************************
     ** The user may use the panel: enabled, signed in, assistant.hasAccess.
     *******************************************************************************/

qbit-assistant/src/main/java/com/kingsrook/qbits/assistant/api/AssistantRoutes.java

@@ -17,12 +17,12 @@
 package com.kingsrook.qbits.assistant.api;
 
 
+import com.kingsrook.qbits.assistant.api.specs.AssistantSpecs;
 import com.kingsrook.qqq.backend.core.model.metadata.QInstance;
 import com.kingsrook.qqq.backend.core.model.metadata.code.QCodeReference;
-import com.kingsrook.qbits.assistant.api.specs.AssistantSpecs;
 import com.kingsrook.qqq.backend.core.utils.CollectionUtils;
-import com.kingsrook.qqq.middleware.javalin.specs.extensions.MiddlewareSpecExtensionsMetaData;
 import com.kingsrook.qqq.middleware.javalin.QJavalinMetaData;
+import com.kingsrook.qqq.middleware.javalin.specs.extensions.MiddlewareSpecExtensionsMetaData;
 
 
 /*******************************************************************************

qbit-assistant/src/main/java/com/kingsrook/qbits/assistant/api/TurnStreams.java

@@ -21,6 +21,7 @@ import java.io.IOException;
 import java.io.OutputStream;
 import java.nio.charset.StandardCharsets;
 import java.util.List;
+import java.util.Map;
 import com.kingsrook.qbits.assistant.engine.TurnEvent;
 import com.kingsrook.qbits.assistant.engine.TurnEventLog;
 import com.kingsrook.qqq.backend.core.logging.QLogger;
@@ -101,7 +102,7 @@ public final class TurnStreams
          OutputStream out       = startStream(context);
          int          last      = after;
          long         lastWrite = System.currentTimeMillis();
-         long         giveUpAt  = System.currentTimeMillis() + (api.maxTurnSeconds() + 60L) * 1000L;
+         long         giveUpAt  = System.currentTimeMillis() + api.maxStreamSeconds() * 1000L;
          AssistantApi.TurnEvents current = first;
          while(true)
          {
@@ -113,10 +114,16 @@ public final class TurnStreams
                lastWrite = System.currentTimeMillis();
                ended |= event.isTerminal();
             }
-            if(ended || (current.finished() && !current.more()) || System.currentTimeMillis() > giveUpAt)
+            if(ended || (current.finished() && !current.more()))
             {
                return;
             }
+            if(System.currentTimeMillis() > giveUpAt)
+            {
+               write(out, new TurnEvent(last + 1, TurnEvent.ERROR, Map.of("code", "TIMEOUT", "message", "The event stream timed out. Reconnect to check this answer.")).toSseFrame());
+               write(out, new TurnEvent(last + 2, TurnEvent.MESSAGE_END, Map.of("status", "ERROR", "stopReason", "stream_timeout")).toSseFrame());
+               return;
+            }
             if(!current.more())
             {
                Thread.sleep(REMOTE_POLL_MS);

qbit-assistant/src/main/java/com/kingsrook/qbits/assistant/api/specs/AssistantSpecs.java

@@ -61,7 +61,7 @@ import io.javalin.http.HttpStatus;
 public final class AssistantSpecs
 {
    public static final String EXTENSION_NAME    = "assistant";
-   public static final String EXTENSION_VERSION = "1.1.0";
+   public static final String EXTENSION_VERSION = "1.2.0";
    public static final String PREFIX            = "/assistant";
 
 
@@ -94,6 +94,7 @@ public final class AssistantSpecs
          .withSpec(StartTurnSpec.class)
          .withSpec(TurnEventsSpec.class)
          .withSpec(CancelTurnSpec.class)
+         .withSpec(ActiveTurnsSpec.class)
          .withSpec(FeedbackSpec.class)
          .withSpec(GetActionSpec.class)
          .withSpec(ConfirmActionSpec.class)
@@ -218,9 +219,14 @@ public final class AssistantSpecs
          "href", string("After a confirm: the written record's /app link.").withNullable(true)));
       rs.put("AssistantAccessResponseV1", object("Explain access: per table, the user's UI permissions, the assistant's data access, and each tool's verdict.",
          "tables", array(freeObject("table, label, dataAccess, dataAccessSource, ui {visible, read, insert, edit, delete}, operations [{tool, operation, allowed, reason}]."), null)));
-      rs.put("AssistantTurnEventV1", object("One server-sent event of a turn (event: <type>, id: <seq>, data: this object). Types: message.start, text.delta, tool.start, tool.result, ui.navigate, notice, usage, message.end, error, ping.",
+      rs.put("AssistantActiveTurnsResponseV1", object("The caller's active runs, newest first; stale leases are reaped.",
+         "turns", array(object("An active assistant run.", "turnId", integer(null), "conversationId", integer(null),
+            "assistantMessageId", integer(null), "userMessageId", integer(null), "status", string("RUNNING or CANCELLING."),
+            "phase", string(null), "startedAt", string("ISO-8601."), "heartbeatAt", string("ISO-8601."),
+            "elapsedMs", integer(null), "live", bool("Running on this replica."), "concurrencyMode", string("SUPERSEDE or CONCURRENT.")), null)));
+      rs.put("AssistantTurnEventV1", object("One server-sent event of a turn (event: <type>, id: <seq>, data: this object). Types: message.start, turn.phase, text.delta, tool.start, tool.result, ui.navigate, notice, usage, message.end, error, ping.",
          "seq", integer("Sequence number; resume with ?after=<seq>."), "type", string("The event type (also the SSE event name)."),
-         "data", freeObject("The event's fields, by type.")));
+         "data", freeObject("The event's fields, by type. message.start includes startedAt (ISO-8601). turn.phase includes phase (thinking, tool, writing), optional toolName and label.")));
       rs.put("AssistantErrorV1", object("An error.", "error", string("A message for the user."), "code", string("BUDGET, RATE_LIMIT, NOT_CONFIGURED, KILL_SWITCH, DISABLED, NO_PERMISSION...").withNullable(true)));
       return (rs);
    }
@@ -562,6 +568,67 @@ public final class AssistantSpecs
 
 
 
+   /*******************************************************************************
+    ** GET /assistant/turns/active
+    *******************************************************************************/
+   public static class ActiveTurnsSpec extends AssistantJsonSpec
+   {
+      /*******************************************************************************
+       ** HTTP method.
+       *******************************************************************************/
+      @Override
+      protected HttpMethod method()
+      {
+         return (HttpMethod.GET);
+      }
+
+
+
+      /*******************************************************************************
+       ** Route path.
+       *******************************************************************************/
+      @Override
+      protected String path()
+      {
+         return (PREFIX + "/turns/active");
+      }
+
+
+
+      /*******************************************************************************
+       ** Operation summary.
+       *******************************************************************************/
+      @Override
+      protected String summary()
+      {
+         return ("Find the user's active assistant runs");
+      }
+
+
+
+      /*******************************************************************************
+       ** Response schema.
+       *******************************************************************************/
+      @Override
+      protected String getResponseSchemaName()
+      {
+         return ("AssistantActiveTurnsResponseV1");
+      }
+
+
+
+      /*******************************************************************************
+       ** Runs in the invoker's authenticated user session.
+       *******************************************************************************/
+      @Override
+      protected Object handle(AssistantApi api, JsonInput input) throws Exception
+      {
+         return (api.activeTurns());
+      }
+   }
+
+
+
    /*******************************************************************************
     ** POST /assistant/conversations
     *******************************************************************************/
@@ -844,7 +911,7 @@ public final class AssistantSpecs
       @Override
       protected Schema defineRequestBodySchema()
       {
-         return (object("The user's text and the page context hint.", "text", string("The user's message."), "pageContext", freeObject("Where the user is in the app.")));
+         return (object("The user's text and the page context hint.", "text", string("The user's message."), "pageContext", freeObject("Where the user is in the app."), "concurrency", string("supersede or concurrent (case-insensitive); defaults to the host configuration.")));
       }
 
 
@@ -1038,10 +1105,24 @@ public final class AssistantSpecs
 
 
 
+      /*******************************************************************************
+       ** Older replicas can still return 202 during a rolling upgrade. New
+       ** replicas return 200 for both active and already finished turns.
+       *******************************************************************************/
+      @Override
+      public List<BasicResponse> defineAdditionalBasicResponses()
+      {
+         List<BasicResponse> responses = new java.util.ArrayList<>(super.defineAdditionalBasicResponses());
+         responses.add(new BasicResponse(HttpStatus.ACCEPTED, "Legacy replica: cancellation accepted", "AssistantStatusResponseV1"));
+         return (responses);
+      }
+
+
+
       @Override
       protected HttpStatus successStatus()
       {
-         return (HttpStatus.ACCEPTED);
+         return (HttpStatus.OK);
       }
    }
 

qbit-assistant/src/main/java/com/kingsrook/qbits/assistant/engine/RateLimiter.java

@@ -26,15 +26,12 @@ import java.util.Map;
 
 
 /*******************************************************************************
- ** Per-user turn rate limits (spec 3.9): turns started per minute and turns
- ** running at once. In memory, per replica - with several replicas the
- ** effective limit is per replica (the concurrent limit is also checked
- ** against the turn table by the API).
+ ** Per-user starts per minute, in memory per replica. The API implements
+ ** concurrency by superseding turns, never by refusing another question.
  *******************************************************************************/
 public class RateLimiter
 {
    private final Map<String, Deque<Instant>> starts  = new HashMap<>();
-   private final Map<String, Integer>        running = new HashMap<>();
    private final Clock                       clock;
 
 
@@ -61,17 +58,12 @@ public class RateLimiter
          queue.pollFirst();
       }
 
-      if(running.getOrDefault(userId, 0) >= concurrent)
-      {
-         return ("You already have an assistant answer in progress. Wait for it to finish or stop it.");
-      }
       if(queue.size() >= perMinute)
       {
          return ("Too many assistant requests in the last minute. Try again shortly.");
       }
 
       queue.addLast(now);
-      running.merge(userId, 1, Integer::sum);
       return (null);
    }
 
@@ -82,7 +74,7 @@ public class RateLimiter
     *******************************************************************************/
    public synchronized void release(String userId)
    {
-      running.computeIfPresent(userId, (k, v) -> v <= 1 ? null : v - 1);
+      // Only starts per minute are counted; completion does not refund a start.
    }
 
 }

qbit-assistant/src/main/java/com/kingsrook/qbits/assistant/engine/RunningTurn.java

@@ -17,7 +17,10 @@
 package com.kingsrook.qbits.assistant.engine;
 
 
+import java.time.Instant;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Consumer;
 import com.kingsrook.qbits.assistant.spi.StreamHandle;
 
 
@@ -30,6 +33,14 @@ public class RunningTurn
    private final String                        userId;
    private final TurnEventLog                  log          = new TurnEventLog();
    private final AtomicReference<String>       cancelReason = new AtomicReference<>();
+   private final AtomicBoolean finalized = new AtomicBoolean();
+   private Instant startedAt;
+   private volatile String phase = "starting";
+   private volatile String toolName;
+   private volatile Thread engineThread;
+   private volatile Consumer<String> forceFinalizer;
+   private volatile long cancelledNanos;
+   private volatile String trackingId;
    private volatile StreamHandle               currentHandle;
 
 
@@ -39,6 +50,7 @@ public class RunningTurn
     *******************************************************************************/
    public RunningTurn(Integer turnId, String userId)
    {
+      this.startedAt = Instant.now();
       this.turnId = turnId;
       this.userId = userId;
    }
@@ -50,12 +62,24 @@ public class RunningTurn
     *******************************************************************************/
    public void cancel(String reason)
    {
-      if(cancelReason.compareAndSet(null, reason))
+      if(!finalized.get() && cancelReason.compareAndSet(null, reason))
       {
-         StreamHandle handle = currentHandle;
-         if(handle != null)
+         cancelledNanos = System.nanoTime();
+         try
          {
-            handle.cancel();
+            StreamHandle handle = currentHandle;
+            if(handle != null)
+            {
+               handle.cancel();
+            }
+         }
+         finally
+         {
+            Thread thread = engineThread;
+            if(thread != null && thread != Thread.currentThread())
+            {
+               thread.interrupt();
+            }
          }
       }
    }
@@ -124,4 +148,140 @@ public class RunningTurn
       return (log);
    }
 
+
+
+
+   /*******************************************************************************
+    ** Claim terminal processing exactly once.
+    *******************************************************************************/
+   public boolean tryFinalize()
+   {
+      return (finalized.compareAndSet(false, true));
+   }
+
+
+
+   /*******************************************************************************
+    ** Whether terminal processing has been claimed.
+    *******************************************************************************/
+   public boolean isFinalized()
+   {
+      return (finalized.get());
+   }
+
+
+
+   /*******************************************************************************
+    ** Getter for startedAt
+    *******************************************************************************/
+   public Instant getStartedAt()
+   {
+      return (startedAt);
+   }
+
+
+
+   /*******************************************************************************
+    ** Setter for startedAt
+    *******************************************************************************/
+   public void setStartedAt(Instant startedAt)
+   {
+      this.startedAt = startedAt;
+   }
+
+
+
+   /*******************************************************************************
+    ** Getter for phase
+    *******************************************************************************/
+   public String getPhase()
+   {
+      return (phase);
+   }
+
+
+
+   /*******************************************************************************
+    ** Getter for toolName
+    *******************************************************************************/
+   public String getToolName()
+   {
+      return (toolName);
+   }
+
+
+
+   /*******************************************************************************
+    ** Record the current phase and optional tool.
+    *******************************************************************************/
+   public void setPhase(String phase, String toolName)
+   {
+      this.phase = phase;
+      this.toolName = toolName;
+   }
+
+
+
+   /*******************************************************************************
+    ** Record the thread to interrupt when cancelling.
+    *******************************************************************************/
+   public void setEngineThread(Thread engineThread)
+   {
+      this.engineThread = engineThread;
+   }
+
+
+
+   /*******************************************************************************
+    ** Install the engine finalizer before registration.
+    *******************************************************************************/
+   public void setForceFinalizer(Consumer<String> forceFinalizer)
+   {
+      this.forceFinalizer = forceFinalizer;
+   }
+
+
+
+   /*******************************************************************************
+    ** Force terminal processing using the original user session.
+    *******************************************************************************/
+   public void forceFinalize(String reason)
+   {
+      Consumer<String> finalizer = forceFinalizer;
+      if(finalizer != null)
+      {
+         finalizer.accept(reason);
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** Whether cancellation has exceeded its bounded grace period.
+    *******************************************************************************/
+   public boolean cancelGraceElapsed(int seconds)
+   {
+      return (isCancelled() && cancelledNanos != 0 && System.nanoTime() - cancelledNanos >= seconds * 1_000_000_000L);
+   }
+
+
+
+   /*******************************************************************************
+    ** Getter for trackingId
+    *******************************************************************************/
+   public String getTrackingId()
+   {
+      return (trackingId);
+   }
+
+
+
+   /*******************************************************************************
+    ** Setter for trackingId
+    *******************************************************************************/
+   public void setTrackingId(String trackingId)
+   {
+      this.trackingId = trackingId;
+   }
+
 }

qbit-assistant/src/main/java/com/kingsrook/qbits/assistant/engine/TurnEngine.java

@@ -102,6 +102,10 @@ public class TurnEngine implements Runnable
 {
    private static final QLogger LOG = QLogger.getLogger(TurnEngine.class);
 
+   public static final String SUPERSEDED_TEXT = "Stopped because you asked something else.";
+   public static final String TIMEOUT_TEXT = "The assistant took too long to answer, so it was stopped. Ask again.";
+   public static final String RESTART_TEXT = "The server restarted while answering. Ask again.";
+
    private static final int MAX_INPUT_JSON_CHARS  = 4000;
 
    private static final AiRedactor INPUT_REDACTOR = new AiRedactor(List.of());
@@ -175,6 +179,10 @@ public class TurnEngine implements Runnable
       this.policy = policy;
       this.running = running;
       this.softBudgetNotice = softBudgetNotice;
+      this.startedAt = turn.getStartedAt() == null ? runtime.getClock().instant() : turn.getStartedAt();
+      this.deadline = startedAt.plusSeconds(config.getMaxTurnSeconds());
+      running.setStartedAt(startedAt);
+      running.setForceFinalizer(this::forceFinish);
    }
 
 
@@ -198,8 +206,11 @@ public class TurnEngine implements Runnable
    @Override
    public void run()
    {
-      startedAt = runtime.getClock().instant();
-      deadline = startedAt.plusSeconds(config.getMaxTurnSeconds());
+      if(running.isFinalized())
+      {
+         return;
+      }
+      running.setEngineThread(Thread.currentThread());
 
       String status     = "COMPLETE";
       String stopReason = null;
@@ -209,6 +220,7 @@ public class TurnEngine implements Runnable
       try
       {
          QContext.init(runtime.getQInstance(), session);
+         startWatchdog();
          scheduledTask = runtime.getScheduledTurn().task(conversation.getId());
          if(conversation.getScheduledTaskId() != null && scheduledTask == null)
          {
@@ -218,9 +230,9 @@ public class TurnEngine implements Runnable
          ScheduledTurn.checkCost(runtime, conversation.getId(), turn.getId());
          classification = new TurnClassification(config.getClassificationSource(), conversation, pageContext);
          store.saveClassification(userId, conversation.getId(), turn.getId(), classification);
-         startKillSwitchWatcher();
 
-         emit(TurnEvent.MESSAGE_START, map("turnId", turn.getId(), "conversationId", conversation.getId(), "userMessageId", userMessage.getId(), "messageId", assistantMessage.getId()));
+
+         emit(TurnEvent.MESSAGE_START, map("turnId", turn.getId(), "conversationId", conversation.getId(), "userMessageId", userMessage.getId(), "messageId", assistantMessage.getId(), "startedAt", startedAt.toString()));
          if(softBudgetNotice != null)
          {
             notice("warning", softBudgetNotice);
@@ -232,6 +244,7 @@ public class TurnEngine implements Runnable
          ModelRouter.Route route;
          try
          {
+            phase("thinking", null);
             route = router.route(session, conversation, turn, userText, pageContext, policy, classification, running, deadline, text -> notice("warning", text));
          }
          finally
@@ -420,8 +433,21 @@ public class TurnEngine implements Runnable
       }
       finally
       {
-         finished = true;
+         // Clear interruption while persisting the terminal state.
+         boolean interrupted = Thread.interrupted();
+         if(running.isCancelled())
+         {
+            Stop stop = cancelledStop();
+            status = stop.status();
+            stopReason = stop.stopReason();
+            errorCode = stop.errorCode();
+            errorText = stop.message();
+         }
          finish(status, stopReason, errorCode, errorText);
+         if(interrupted)
+         {
+            Thread.currentThread().interrupt();
+         }
          QContext.clear();
       }
    }
@@ -429,35 +455,56 @@ public class TurnEngine implements Runnable
 
 
    /*******************************************************************************
-    ** Poll the kill switch while the turn runs (with the user's own session),
-    ** so a flip cancels the turn - and every other turn here - even while it
-    ** waits on the model.
+    ** Renew the lease, poll cancellation and the kill switch with the user's
+    ** own session, and enforce a hard deadline even if a provider is wedged.
     *******************************************************************************/
-   private void startKillSwitchWatcher()
+   private void startWatchdog()
    {
-      long pollMillis = config.getKillSwitchPollMillis() == null ? 2000 : config.getKillSwitchPollMillis();
-      Thread.ofVirtual().name("assistant-killswitch-" + turn.getId()).start(() ->
+      long heartbeatMillis = config.getTurnHeartbeatSeconds() * 1000L;
+      long pollMillis = Math.min(heartbeatMillis, config.getKillSwitchPollMillis() == null ? 2000 : config.getKillSwitchPollMillis());
+      Thread.ofVirtual().name("assistant-watchdog-" + turn.getId()).start(() ->
       {
+         long lastHeartbeat = System.nanoTime();
          try
          {
-            while(!finished && !running.isCancelled())
+            QContext.init(runtime.getQInstance(), session);
+            while(!running.isFinalized())
             {
                Thread.sleep(pollMillis);
-               if(finished)
+               if(running.isFinalized())
                {
-                  return;
+                  break;
                }
-               QContext.init(runtime.getQInstance(), session);
                try
                {
+                  if(System.nanoTime() - lastHeartbeat >= heartbeatMillis * 1_000_000L)
+                  {
+                     lastHeartbeat = System.nanoTime();
+                     heartbeat();
+                  }
                   if(runtime.getPolicyService().isKillSwitchOn())
                   {
                      runtime.cancelAll("KILL_SWITCH");
                   }
                }
+               catch(Exception e)
+               {
+                  LOG.warn("Assistant watchdog tick failed", hipaaSafe(e), logPair("turnId", turn.getId()));
+               }
                finally
                {
-                  QContext.clear();
+                  // Deadlines do not depend on successful database or policy reads.
+                  Instant now = runtime.getClock().instant();
+                  if(!now.isBefore(deadline))
+                  {
+                     safely(() -> running.cancel("TIMEOUT"));
+                  }
+                  if(!now.isBefore(deadline.plusSeconds(config.getTurnForceFinalizeGraceSeconds()))
+                     || running.cancelGraceElapsed(config.getTurnForceFinalizeGraceSeconds()))
+                  {
+                     Stop stop = running.isCancelled() ? cancelledStop() : new Stop("ERROR", "TIMEOUT", TIMEOUT_TEXT, "timeout");
+                     finish(stop.status(), stop.stopReason(), stop.errorCode(), stop.message());
+                  }
                }
             }
          }
@@ -465,11 +512,63 @@ public class TurnEngine implements Runnable
          {
             Thread.currentThread().interrupt();
          }
+         finally
+         {
+            QContext.clear();
+         }
       });
    }
 
 
 
+   /*******************************************************************************
+    ** Renew only an active row, then observe persisted cancellation requests.
+    *******************************************************************************/
+   private synchronized void heartbeat() throws QException
+   {
+      if(running.isFinalized())
+      {
+         return;
+      }
+      AssistantTurn row = store.getTurn(userId, turn.getId());
+      if(row == null || !("RUNNING".equals(row.getStatus()) || "CANCELLING".equals(row.getStatus())))
+      {
+         safely(() -> running.cancel("USER"));
+         finish(row == null ? "ERROR" : row.getStatus(), row == null ? "interrupted" : row.getStopReason(),
+            row == null ? "INTERNAL" : row.getErrorCode(), null);
+         return;
+      }
+      store.updateFields(AssistantTurn.TABLE_NAME, new QRecord().withValue("id", turn.getId())
+         .withValue("heartbeatAt", runtime.getClock().instant()).withValue("phase", running.getPhase()));
+      row = store.getTurn(userId, turn.getId());
+      if(row != null && (row.getCancelRequestedAt() != null || "CANCELLING".equals(row.getStatus())))
+      {
+         running.cancel(row.getCancelReason() == null ? "USER" : row.getCancelReason());
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** Finalize from shutdown using the original authenticated user's context.
+    *******************************************************************************/
+   private void forceFinish(String reason)
+   {
+      try
+      {
+         QContext.init(runtime.getQInstance(), session);
+         safely(() -> running.cancel(reason));
+         Stop stop = "SHUTDOWN".equals(reason) ? new Stop("ERROR", "INTERRUPTED", RESTART_TEXT, "interrupted") : cancelledStop();
+         finish(stop.status(), stop.stopReason(), stop.errorCode(), stop.message());
+      }
+      finally
+      {
+         QContext.clear();
+      }
+   }
+
+
+
    /*******************************************************************************
     ** Why a turn stops.
     *******************************************************************************/
@@ -504,14 +603,15 @@ public class TurnEngine implements Runnable
       }
       if(!runtime.getClock().instant().isBefore(deadline))
       {
-         return (new Stop("ERROR", "TIMEOUT", "The assistant ran out of time for this question.", "timeout"));
+         running.cancel("TIMEOUT");
+         return (cancelledStop());
       }
       try
       {
          AssistantTurn row = store.getTurn(userId, turn.getId());
          if(row != null && "CANCELLING".equals(row.getStatus()))
          {
-            running.cancel("USER");
+            running.cancel(row.getCancelReason() == null ? "USER" : row.getCancelReason());
             return (cancelledStop());
          }
       }
@@ -529,6 +629,18 @@ public class TurnEngine implements Runnable
     *******************************************************************************/
    private Stop cancelledStop()
    {
+      if("TIMEOUT".equals(running.getCancelReason()))
+      {
+         return (new Stop("ERROR", "TIMEOUT", TIMEOUT_TEXT, "timeout"));
+      }
+      if("SHUTDOWN".equals(running.getCancelReason()))
+      {
+         return (new Stop("ERROR", "INTERRUPTED", RESTART_TEXT, "interrupted"));
+      }
+      if("SUPERSEDED".equals(running.getCancelReason()))
+      {
+         return (new Stop("CANCELLED", null, SUPERSEDED_TEXT, ModelResponse.STOP_CANCELLED));
+      }
       if("KILL_SWITCH".equals(running.getCancelReason()))
       {
          String reason = StringUtils.hasContent(policy.killSwitchReason()) ? " " + policy.killSwitchReason() : "";
@@ -618,6 +730,7 @@ public class TurnEngine implements Runnable
          @Override
          public void onTextDelta(String text)
          {
+            phase("writing", null);
             bufferText(text);
          }
       };
@@ -639,6 +752,7 @@ public class TurnEngine implements Runnable
          TurnDataRouting.beforeModelCall(runtime, classification, turn, active);
          fallback.beforeCall(active);
          modelCallCount++;
+         phase("thinking", null);
          StreamHandle handle = provider.stream(request.copy(), fallback.listener(listener));
          running.setCurrentHandle(handle);
          try
@@ -707,6 +821,7 @@ public class TurnEngine implements Runnable
             continue;
          }
          toolCallCount++;
+         phase("tool", use.getToolName());
          emit(TurnEvent.TOOL_START, map("messageId", assistantMessage.getId(), "toolCallId", use.getToolUseId(), "name", use.getToolName(), "summary", ToolLabels.running(use.getToolName())));
 
          if(!allowedTools.contains(use.getToolName()))
@@ -996,93 +1111,100 @@ public class TurnEngine implements Runnable
    /*******************************************************************************
     ** Persist the message, turn, conversation and usage; emit the end events.
     *******************************************************************************/
-   private void finish(String status, String stopReason, String errorCode, String errorText)
+   private synchronized void finish(String status, String stopReason, String errorCode, String errorText)
    {
+      if(!running.tryFinalize())
+      {
+         return;
+      }
       try
       {
-         persistClassification();
-         flushText(true);
-         Instant now = runtime.getClock().instant();
-
-         if(errorText != null)
-         {
-            parts.addNotice("error", errorText);
-         }
-
-         String model = this.model != null ? this.model : (policy == null ? null : policy.mainModel());
+         AssistantTurn persistedTurn = null;
          try
          {
-            store.updateFields(AssistantMessage.TABLE_NAME, new QRecord()
-               .withValue("id", assistantMessage.getId())
-               .withValue("status", status)
-               .withValue("model", model)
-               .withValue("partsJson", parts.toJson()));
-
-            AssistantConversation current = store.getConversation(userId, conversation.getId());
-            if(current != null)
-            {
-               store.updateFields(AssistantConversation.TABLE_NAME, new QRecord()
-                  .withValue("id", current.getId())
-                  .withValue("lastMessageAt", now)
-                  .withValue("unreadCount", (current.getUnreadCount() == null ? 0 : current.getUnreadCount()) + 1)
-                  .withValue("totalTokensIn", nz(current.getTotalTokensIn()) + nz(usage.getInputTokens()) + nz(usage.getCacheReadTokens()) + nz(usage.getCacheWriteTokens()))
-                  .withValue("totalTokensOut", nz(current.getTotalTokensOut()) + nz(usage.getOutputTokens()))
-                  .withValue("totalCostMicros", nz(current.getTotalCostMicros()) + costMicros));
-            }
-
-            store.addUsage(userId, LocalDate.now(runtime.getClock().withZone(ZoneOffset.UTC)), usage, costMicros, true);
+            persistedTurn = store.getTurn(userId, turn.getId());
          }
-         catch(QException e)
+         catch(Exception e)
          {
-            LOG.warn("Could not persist the end of an assistant turn", hipaaSafe(e), logPair("turnId", turn.getId()));
+            LOG.warn("Could not read final assistant status", hipaaSafe(e), logPair("turnId", turn.getId()));
+         }
+         boolean alreadyTerminal = persistedTurn != null && !("RUNNING".equals(persistedTurn.getStatus()) || "CANCELLING".equals(persistedTurn.getStatus()));
+         if(alreadyTerminal)
+         {
+            status = persistedTurn.getStatus();
+            stopReason = persistedTurn.getStopReason();
+            errorCode = persistedTurn.getErrorCode();
+         }
+         String finalStatus = status;
+         String finalStopReason = stopReason;
+         String finalErrorCode = errorCode;
+         String model = this.model != null ? this.model : (policy == null ? null : policy.mainModel());
+         Instant now = runtime.getClock().instant();
+         safely(() -> flushText(true));
+         if(errorText != null && !alreadyTerminal)
+         {
+            parts.addNotice("CANCELLED".equals(status) ? "info" : "error", errorText);
+         }
+         running.setPhase("done", null);
+         if(!alreadyTerminal)
+         {
+            safely(() -> persistClassification());
+            safely(() -> store.updateFields(AssistantMessage.TABLE_NAME, new QRecord()
+               .withValue("id", assistantMessage.getId()).withValue("status", finalStatus)
+               .withValue("model", model).withValue("partsJson", parts.toJson())));
          }
 
-         /////////////////////////////////////////////////////////////////////
-         // terminal events are persisted BEFORE the turn row turns final, //
-         // so a replay of a finished turn always ends with message.end    //
-         /////////////////////////////////////////////////////////////////////
          emit(TurnEvent.USAGE, map("turnId", turn.getId(), "inputTokens", usage.getInputTokens(), "outputTokens", usage.getOutputTokens(),
             "cacheReadTokens", usage.getCacheReadTokens(), "cacheWriteTokens", usage.getCacheWriteTokens(), "costMicros", costMicros));
          if(errorCode != null)
          {
             emit(TurnEvent.ERROR, map("code", errorCode, "message", errorText));
          }
-         Map<String, Object> end = map("messageId", assistantMessage.getId(), "status", status);
-         if(stopReason != null)
+         emit(TurnEvent.MESSAGE_END, map("messageId", assistantMessage.getId(), "status", status, "stopReason", stopReason));
+         if(!alreadyTerminal)
          {
-            end.put("stopReason", stopReason);
+            safely(this::persistPendingEvents);
+            // Accounting failures cannot skip the terminal row or local cleanup.
+            safely(() ->
+            {
+               store.updateRunningTurn(userId, new QRecord()
+                  .withValue("id", turn.getId())
+                  .withValue("status", finalStatus)
+                  .withValue("phase", "done")
+                  .withValue("stopReason", truncate(finalStopReason, 64))
+                  .withValue("errorCode", finalErrorCode)
+                  .withValue("cancelReason", running.getCancelReason())
+                  .withValue("model", model)
+                  .withValue("providerId", active == null ? null : active.providerId())
+                  .withValue("routeDecision", turn.getRouteDecision())
+                  .withValue("routeSource", turn.getRouteSource())
+                  .withValue("fallbackCount", turn.getFallbackCount())
+                  .withValue("endedAt", now)
+                  .withValue("toolCallCount", toolCallCount)
+                  .withValue("modelCallCount", modelCallCount)
+                  .withValue("inputTokens", usage.getInputTokens())
+                  .withValue("outputTokens", usage.getOutputTokens())
+                  .withValue("cacheReadTokens", usage.getCacheReadTokens())
+                  .withValue("cacheWriteTokens", usage.getCacheWriteTokens())
+                  .withValue("costMicros", costMicros)
+                  .withValue("providerRequestIds", requestIds.isEmpty() ? null : String.join(",", requestIds)));
+            });
+            safely(() ->
+            {
+               AssistantConversation current = store.getConversation(userId, conversation.getId());
+               if(current != null)
+               {
+                  store.updateFields(AssistantConversation.TABLE_NAME, new QRecord()
+                     .withValue("id", current.getId())
+                     .withValue("lastMessageAt", now)
+                     .withValue("unreadCount", (current.getUnreadCount() == null ? 0 : current.getUnreadCount()) + 1)
+                     .withValue("totalTokensIn", nz(current.getTotalTokensIn()) + nz(usage.getInputTokens()) + nz(usage.getCacheReadTokens()) + nz(usage.getCacheWriteTokens()))
+                     .withValue("totalTokensOut", nz(current.getTotalTokensOut()) + nz(usage.getOutputTokens()))
+                     .withValue("totalCostMicros", nz(current.getTotalCostMicros()) + costMicros));
+               }
+            });
+            safely(() -> store.addUsage(userId, LocalDate.now(runtime.getClock().withZone(ZoneOffset.UTC)), usage, costMicros, true));
          }
-         emit(TurnEvent.MESSAGE_END, end);
-         persistPendingEvents();
-
-         try
-         {
-            store.updateFields(AssistantTurn.TABLE_NAME, new QRecord()
-               .withValue("id", turn.getId())
-               .withValue("status", status)
-               .withValue("stopReason", truncate(stopReason, 64))
-               .withValue("errorCode", errorCode)
-               .withValue("cancelReason", running.getCancelReason())
-               .withValue("model", model)
-               .withValue("providerId", active == null ? null : active.providerId())
-               .withValue("routeDecision", turn.getRouteDecision())
-               .withValue("routeSource", turn.getRouteSource())
-               .withValue("fallbackCount", turn.getFallbackCount())
-               .withValue("endedAt", now)
-               .withValue("toolCallCount", toolCallCount)
-               .withValue("modelCallCount", modelCallCount)
-               .withValue("inputTokens", usage.getInputTokens())
-               .withValue("outputTokens", usage.getOutputTokens())
-               .withValue("cacheReadTokens", usage.getCacheReadTokens())
-               .withValue("cacheWriteTokens", usage.getCacheWriteTokens())
-               .withValue("costMicros", costMicros)
-               .withValue("providerRequestIds", requestIds.isEmpty() ? null : String.join(",", requestIds)));
-         }
-         catch(QException e)
-         {
-            LOG.warn("Could not persist the end of an assistant turn", hipaaSafe(e), logPair("turnId", turn.getId()));
-         }
-
          LOG.info("Assistant turn finished",
             logPair("turnId", turn.getId()),
             logPair("conversationId", conversation.getId()),
@@ -1091,6 +1213,7 @@ public class TurnEngine implements Runnable
             logPair("status", status),
             logPair("stopReason", stopReason),
             logPair("errorCode", errorCode),
+            logPair("cancelReason", running.getCancelReason()),
             logPair("modelCalls", modelCallCount),
             logPair("toolCalls", toolCallCount),
             logPair("inputTokens", usage.getInputTokens()),
@@ -1100,29 +1223,90 @@ public class TurnEngine implements Runnable
             logPair("costMicros", costMicros),
             logPair("durationMs", Duration.between(startedAt, now).toMillis()));
       }
-      catch(QException | RuntimeException e)
-      {
-         LOG.warn("Assistant turn finish failed", hipaaSafe(e), logPair("turnId", turn.getId()));
-      }
       finally
       {
+         finished = true;
          running.getLog().close();
-         if(scheduledTask != null)
+         safely(() ->
          {
-            runtime.getScheduledTurn().detach(conversation.getId(), session.getUuid());
+            if(scheduledTask != null)
+            {
+               runtime.getScheduledTurn().detach(conversation.getId(), session.getUuid());
+            }
+         });
+         String finalStatus = status;
+         String finalText = errorText;
+         try
+         {
+            safely(() -> config.getRunTracker().finish(running.getTrackingId(), finalStatus, finalText));
+         }
+         finally
+         {
+            runtime.unregister(turn.getId());
+            runtime.getRateLimiter().release(userId);
          }
-         runtime.unregister(turn.getId());
-         runtime.getRateLimiter().release(userId);
       }
    }
 
 
 
+   /*******************************************************************************
+    ** One independently fallible finalization operation.
+    *******************************************************************************/
+   @FunctionalInterface
+   private interface FinishStep
+   {
+      /*******************************************************************************
+       ** Execute the step.
+       *******************************************************************************/
+      void run() throws Exception;
+   }
+
+
+
+   /*******************************************************************************
+    ** A failure in a collaborator must not strand the run.
+    *******************************************************************************/
+   private void safely(FinishStep step)
+   {
+      try
+      {
+         step.run();
+      }
+      catch(Exception e)
+      {
+         LOG.warn("Assistant lifecycle step failed", hipaaSafe(e), logPair("turnId", turn.getId()));
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** Emit and track only phase changes, including the current tool label.
+    *******************************************************************************/
+   private synchronized void phase(String phase, String toolName)
+   {
+      if(running.isFinalized() || (phase.equals(running.getPhase()) && Objects.equals(toolName, running.getToolName())))
+      {
+         return;
+      }
+      running.setPhase(phase, toolName);
+      String label = toolName == null ? phase : ToolLabels.running(toolName);
+      emit(TurnEvent.TURN_PHASE, map("phase", phase, "toolName", toolName, "label", label));
+      safely(() -> config.getRunTracker().progress(running.getTrackingId(), phase, label));
+   }
+
+
+
    /*******************************************************************************
     ** Buffer streamed text; emit it in small chunks (provider thread).
     *******************************************************************************/
-   private void bufferText(String text)
+   private synchronized void bufferText(String text)
    {
+      if(running.isFinalized())
+      {
+         return;
+      }
       synchronized(textBuffer)
       {
          textBuffer.append(text);
@@ -1135,7 +1319,7 @@ public class TurnEngine implements Runnable
    /*******************************************************************************
     ** Emit buffered text as one text.delta (when big or old enough, or forced).
     *******************************************************************************/
-   private void flushText(boolean force)
+   private synchronized void flushText(boolean force)
    {
       String chunk;
       synchronized(textBuffer)
@@ -1170,8 +1354,12 @@ public class TurnEngine implements Runnable
     ** Append to the live log; queue for persistence (done on the engine
     ** thread, which has the QContext).
     *******************************************************************************/
-   private void emit(String type, Map<String, Object> data)
+   private synchronized void emit(String type, Map<String, Object> data)
    {
+      if(finished)
+      {
+         return;
+      }
       toPersist.add(running.getLog().append(type, data));
    }
 
@@ -1189,7 +1377,7 @@ public class TurnEngine implements Runnable
          {
             store.insertEvent(turn.getId(), userId, event.getSeq(), event.getType(), event.toJson());
          }
-         catch(QException e)
+         catch(Exception e)
          {
             LOG.warn("Could not persist assistant turn event", hipaaSafe(e), logPair("turnId", turn.getId()), logPair("seq", event.getSeq()));
          }

qbit-assistant/src/main/java/com/kingsrook/qbits/assistant/engine/TurnEvent.java

@@ -29,6 +29,7 @@ import com.kingsrook.qqq.backend.core.utils.JsonUtils;
  *******************************************************************************/
 public class TurnEvent
 {
+   public static final String TURN_PHASE = "turn.phase";
    public static final String MESSAGE_START = "message.start";
    public static final String TEXT_DELTA    = "text.delta";
    public static final String TOOL_START    = "tool.start";

qbit-assistant/src/main/java/com/kingsrook/qbits/assistant/jobs/AssistantRunTracker.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2026 Kingsrook, LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.kingsrook.qbits.assistant.jobs;
+
+
+/*******************************************************************************
+ ** STAND-IN(core=QRun-IO/qqq#1210, removeBy=RC.9): core job tracking
+ ** (jobs_job tracking rows) will implement this contract; hosts may wire their own.
+ *******************************************************************************/
+public interface AssistantRunTracker
+{
+   AssistantRunTracker NOOP = new AssistantRunTracker()
+   {
+      /*******************************************************************************
+       ** No tracking is configured.
+       *******************************************************************************/
+      @Override
+      public String start(String userId, Integer turnId, Integer conversationId, String label)
+      {
+         return (null);
+      }
+
+      /*******************************************************************************
+       ** No tracking is configured.
+       *******************************************************************************/
+      @Override
+      public void progress(String trackingId, String phase, String message)
+      {
+      }
+
+      /*******************************************************************************
+       ** No tracking is configured.
+       *******************************************************************************/
+      @Override
+      public void finish(String trackingId, String status, String message)
+      {
+      }
+   };
+
+   /*******************************************************************************
+    ** Publish a run and return its tracking id.
+    *******************************************************************************/
+   String start(String userId, Integer turnId, Integer conversationId, String label);
+
+   /*******************************************************************************
+    ** Publish a changed phase.
+    *******************************************************************************/
+   void progress(String trackingId, String phase, String message);
+
+   /*******************************************************************************
+    ** Publish the terminal outcome.
+    *******************************************************************************/
+   void finish(String trackingId, String status, String message);
+
+   /*******************************************************************************
+    ** Wire the host's Stop action to the owner's cancellation path.
+    *******************************************************************************/
+   default void onCancel(String trackingId, Runnable cancel)
+   {
+   }
+}

qbit-assistant/src/main/java/com/kingsrook/qbits/assistant/model/AssistantTurn.java

@@ -92,6 +92,21 @@ public class AssistantTurn extends QRecordEntity
    @QField(isEditable = false)
    private Instant endedAt;
 
+   @QField(isEditable = false)
+   private Instant heartbeatAt;
+
+   @QField(isEditable = false, maxLength = 100)
+   private String leaseOwner;
+
+   @QField(isEditable = false)
+   private Instant cancelRequestedAt;
+
+   @QField(isEditable = false, maxLength = 64)
+   private String phase;
+
+   @QField(isEditable = false, maxLength = 16)
+   private String concurrencyMode;
+
    @QField(isEditable = false)
    private Integer toolCallCount;
 
@@ -1011,4 +1026,160 @@ public class AssistantTurn extends QRecordEntity
       this.providerId = providerId;
       return (this);
    }
+
+
+
+   /*******************************************************************************
+    ** Getter for heartbeatAt
+    *******************************************************************************/
+   public Instant getHeartbeatAt()
+   {
+      return (this.heartbeatAt);
+   }
+
+
+
+   /*******************************************************************************
+    ** Setter for heartbeatAt
+    *******************************************************************************/
+   public void setHeartbeatAt(Instant heartbeatAt)
+   {
+      this.heartbeatAt = heartbeatAt;
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for heartbeatAt
+    *******************************************************************************/
+   public AssistantTurn withHeartbeatAt(Instant heartbeatAt)
+   {
+      this.heartbeatAt = heartbeatAt;
+      return (this);
+   }
+
+
+
+   /*******************************************************************************
+    ** Getter for leaseOwner
+    *******************************************************************************/
+   public String getLeaseOwner()
+   {
+      return (this.leaseOwner);
+   }
+
+
+
+   /*******************************************************************************
+    ** Setter for leaseOwner
+    *******************************************************************************/
+   public void setLeaseOwner(String leaseOwner)
+   {
+      this.leaseOwner = leaseOwner;
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for leaseOwner
+    *******************************************************************************/
+   public AssistantTurn withLeaseOwner(String leaseOwner)
+   {
+      this.leaseOwner = leaseOwner;
+      return (this);
+   }
+
+
+
+   /*******************************************************************************
+    ** Getter for cancelRequestedAt
+    *******************************************************************************/
+   public Instant getCancelRequestedAt()
+   {
+      return (this.cancelRequestedAt);
+   }
+
+
+
+   /*******************************************************************************
+    ** Setter for cancelRequestedAt
+    *******************************************************************************/
+   public void setCancelRequestedAt(Instant cancelRequestedAt)
+   {
+      this.cancelRequestedAt = cancelRequestedAt;
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for cancelRequestedAt
+    *******************************************************************************/
+   public AssistantTurn withCancelRequestedAt(Instant cancelRequestedAt)
+   {
+      this.cancelRequestedAt = cancelRequestedAt;
+      return (this);
+   }
+
+
+
+   /*******************************************************************************
+    ** Getter for phase
+    *******************************************************************************/
+   public String getPhase()
+   {
+      return (this.phase);
+   }
+
+
+
+   /*******************************************************************************
+    ** Setter for phase
+    *******************************************************************************/
+   public void setPhase(String phase)
+   {
+      this.phase = phase;
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for phase
+    *******************************************************************************/
+   public AssistantTurn withPhase(String phase)
+   {
+      this.phase = phase;
+      return (this);
+   }
+
+
+
+   /*******************************************************************************
+    ** Getter for concurrencyMode
+    *******************************************************************************/
+   public String getConcurrencyMode()
+   {
+      return (this.concurrencyMode);
+   }
+
+
+
+   /*******************************************************************************
+    ** Setter for concurrencyMode
+    *******************************************************************************/
+   public void setConcurrencyMode(String concurrencyMode)
+   {
+      this.concurrencyMode = concurrencyMode;
+   }
+
+
+
+   /*******************************************************************************
+    ** Fluent setter for concurrencyMode
+    *******************************************************************************/
+   public AssistantTurn withConcurrencyMode(String concurrencyMode)
+   {
+      this.concurrencyMode = concurrencyMode;
+      return (this);
+   }
+
 }

qbit-assistant/src/main/java/com/kingsrook/qbits/assistant/persistence/AssistantStore.java

@@ -31,6 +31,7 @@ import com.kingsrook.qbits.assistant.AssistantQBitConfig;
 import com.kingsrook.qbits.assistant.AssistantRuntime;
 import com.kingsrook.qbits.assistant.classification.Classifications;
 import com.kingsrook.qbits.assistant.engine.TurnClassification;
+import com.kingsrook.qbits.assistant.engine.TurnEvent;
 import com.kingsrook.qbits.assistant.model.AssistantBudget;
 import com.kingsrook.qbits.assistant.model.AssistantBudgetEvent;
 import com.kingsrook.qbits.assistant.model.AssistantBudgetOverride;
@@ -384,6 +385,27 @@ public class AssistantStore
 
 
 
+   /*******************************************************************************
+    ** Re-read before a lifecycle update. A completed row is never reopened by
+    ** a late local Stop or overwritten by a second local finalizer. Every read
+    ** and update remains under the caller's own session and owner filter.
+    *******************************************************************************/
+   public boolean updateRunningTurn(String userId, QRecord changes) throws QException
+   {
+      synchronized(QContext.getQInstance())
+      {
+         AssistantTurn current = getTurn(userId, changes.getValueInteger("id"));
+         if(current == null || !("RUNNING".equals(current.getStatus()) || "CANCELLING".equals(current.getStatus())))
+         {
+            return (false);
+         }
+         updateFields(AssistantTurn.TABLE_NAME, changes);
+         return (true);
+      }
+   }
+
+
+
    /*******************************************************************************
     ** One of the user's own pending actions, or null.
     *******************************************************************************/
@@ -411,6 +433,51 @@ public class AssistantStore
     ** Persist one streamed event.
     *******************************************************************************/
    public void insertEvent(Integer turnId, String userId, int seq, String eventType, String dataJson) throws QException
+   {
+      if(TurnEvent.MESSAGE_END.equals(eventType) || TurnEvent.ERROR.equals(eventType))
+      {
+         // Serialize memory-backend callers. The Postgres partial unique index
+         // arbitrates this same race between independent replicas.
+         synchronized(QContext.getQInstance())
+         {
+            if(hasTerminalEvent(userId, turnId))
+            {
+               return;
+            }
+            try
+            {
+               insertStreamEvent(turnId, userId, seq, eventType, dataJson);
+            }
+            catch(QException e)
+            {
+               if(!hasTerminalEvent(userId, turnId))
+               {
+                  throw (e);
+               }
+            }
+         }
+         return;
+      }
+      insertStreamEvent(turnId, userId, seq, eventType, dataJson);
+   }
+
+
+
+   /*******************************************************************************
+    ** Whether a terminal replay frame has already been persisted by any owner.
+    *******************************************************************************/
+   private boolean hasTerminalEvent(String userId, Integer turnId) throws QException
+   {
+      return (!query(AssistantTurnEvent.TABLE_NAME, owned(userId).withCriteria("turnId", QCriteriaOperator.EQUALS, turnId)
+         .withCriteria("eventType", QCriteriaOperator.EQUALS, TurnEvent.MESSAGE_END).withLimit(1), AssistantTurnEvent.class).isEmpty());
+   }
+
+
+
+   /*******************************************************************************
+    ** Persist one frame through the normal encrypted, user-owned store path.
+    *******************************************************************************/
+   private void insertStreamEvent(Integer turnId, String userId, int seq, String eventType, String dataJson) throws QException
    {
       insert(new AssistantTurnEvent()
          .withTurnId(turnId)

qbit-assistant/src/main/resources/db/liquibase/qbit-assistant/assistant-defaults.changelog.sql

@@ -9,6 +9,9 @@
 -- Rules for this file:
 --   * insert-only: every row is inserted only when its natural key is absent,
 --     so an administrator's edits always survive and nothing is ever updated;
+--   * rollback is empty: a seeded row cannot be told apart from a host's own
+--     row with the same name, and Liquibase also rolls back changesets it marked
+--     ran, so undoing would delete the host's data (remove seeded rows by hand);
 --   * no secrets: environment variable NAMES only, never values;
 --   * portable SQL (PostgreSQL and H2): INSERT ... SELECT ... WHERE NOT EXISTS;
 --   * every changeset has a precondition on its table, so a host that has not
@@ -22,7 +25,7 @@
 INSERT INTO assistant_policy (name, kill_switch, writes_require_confirmation, redact_pii, max_rows_per_call, create_date, modify_date)
 SELECT 'default', FALSE, TRUE, TRUE, 50, CURRENT_TIMESTAMP, CURRENT_TIMESTAMP
 WHERE NOT EXISTS (SELECT 1 FROM assistant_policy);
--- rollback DELETE FROM assistant_policy WHERE name = 'default';
+-- rollback empty
 
 -- changeset qbit-assistant:defaults-2
 -- preconditions onFail:MARK_RAN onError:MARK_RAN
@@ -37,7 +40,7 @@ Which tables can I look at?
 What changed in the last 7 days?',
    TRUE, TRUE, CURRENT_TIMESTAMP, CURRENT_TIMESTAMP
 WHERE NOT EXISTS (SELECT 1 FROM assistant_profile WHERE name = 'default' OR is_default = TRUE);
--- rollback DELETE FROM assistant_profile WHERE name = 'default';
+-- rollback empty
 
 -- changeset qbit-assistant:defaults-3
 -- preconditions onFail:MARK_RAN onError:MARK_RAN
@@ -53,7 +56,7 @@ SELECT 'find-and-count', 'Finding, filtering and counting records.',
 5. If the result was truncated, say so and offer the link instead of listing more.',
    TRUE, 'find,show,list,which,how many,count,filter,search,look up', CURRENT_TIMESTAMP, CURRENT_TIMESTAMP
 WHERE NOT EXISTS (SELECT 1 FROM assistant_skill WHERE name = 'find-and-count');
--- rollback DELETE FROM assistant_skill WHERE name = 'find-and-count';
+-- rollback empty
 
 -- changeset qbit-assistant:defaults-4
 -- preconditions onFail:MARK_RAN onError:MARK_RAN
@@ -68,7 +71,7 @@ SELECT 'explain-a-record', 'Summarizing a record and who changed it.',
 4. Link to the record.',
    TRUE, 'explain,summarize,summary,tell me about,what is,status,history,changed,who changed,audit', CURRENT_TIMESTAMP, CURRENT_TIMESTAMP
 WHERE NOT EXISTS (SELECT 1 FROM assistant_skill WHERE name = 'explain-a-record');
--- rollback DELETE FROM assistant_skill WHERE name = 'explain-a-record';
+-- rollback empty
 
 -- changeset qbit-assistant:defaults-5
 -- preconditions onFail:MARK_RAN onError:MARK_RAN
@@ -83,7 +86,7 @@ SELECT 'safe-changes', 'Proposing creates, updates and deletes safely.',
 4. For many rows from a file, use the bulk load tools and always run bulk_load_dry_run and show its summary before bulk_load_run.',
    TRUE, 'change,update,set,edit,create,add,new,delete,remove,fix,rename,import,load', CURRENT_TIMESTAMP, CURRENT_TIMESTAMP
 WHERE NOT EXISTS (SELECT 1 FROM assistant_skill WHERE name = 'safe-changes');
--- rollback DELETE FROM assistant_skill WHERE name = 'safe-changes';
+-- rollback empty
 
 -- changeset qbit-assistant:defaults-6
 -- preconditions onFail:MARK_RAN onError:MARK_RAN
@@ -97,7 +100,7 @@ SELECT 'access-questions', 'Explaining why data is missing or not available.',
 3. Suggest the next step: check the filter, open the list screen, or ask an administrator for access.',
    TRUE, 'cannot see,can''t see,missing,not found,denied,access,permission,not allowed,hidden', CURRENT_TIMESTAMP, CURRENT_TIMESTAMP
 WHERE NOT EXISTS (SELECT 1 FROM assistant_skill WHERE name = 'access-questions');
--- rollback DELETE FROM assistant_skill WHERE name = 'access-questions';
+-- rollback empty
 
 -- changeset qbit-assistant:defaults-7
 -- preconditions onFail:MARK_RAN onError:MARK_RAN
@@ -109,7 +112,7 @@ FROM assistant_profile p, assistant_skill s
 WHERE p.name = 'default'
   AND s.name IN ('find-and-count', 'explain-a-record', 'safe-changes', 'access-questions')
   AND NOT EXISTS (SELECT 1 FROM assistant_profile_skill ps WHERE ps.profile_id = p.id AND ps.skill_id = s.id);
--- rollback DELETE FROM assistant_profile_skill WHERE profile_id IN (SELECT id FROM assistant_profile WHERE name = 'default') AND skill_id IN (SELECT id FROM assistant_skill WHERE name IN ('find-and-count', 'explain-a-record', 'safe-changes', 'access-questions'));
+-- rollback empty
 
 -- changeset qbit-assistant:defaults-8
 -- preconditions onFail:MARK_RAN onError:MARK_RAN
@@ -120,7 +123,7 @@ SELECT 'Monthly spend (whole instance)', TRUE, 'INSTANCE', 'MONTH', 'COST_USD',
    'Starter budget. Warns everyone at 80% of $50 a month, switches to the cheapest allowed model at 100% (or stops when there is none), and stops at 120%. Set Downgrade Model to choose the fallback; add an override to raise it temporarily.',
    CURRENT_TIMESTAMP, CURRENT_TIMESTAMP
 WHERE NOT EXISTS (SELECT 1 FROM assistant_budget);
--- rollback DELETE FROM assistant_budget WHERE name = 'Monthly spend (whole instance)';
+-- rollback empty
 
 -- changeset qbit-assistant:defaults-9
 -- preconditions onFail:MARK_RAN onError:MARK_RAN
@@ -143,7 +146,7 @@ FROM (VALUES
    ('anthropic', 'claude-haiku-4-5', 1.00, 5.00, 0.10, 1.25, 2.00, 'Anthropic list price, 2026-10')
 ) AS v (provider_type, model, input_price, output_price, cache_read, cache_write5m, cache_write1h, notes)
 WHERE NOT EXISTS (SELECT 1 FROM assistant_model_price p);
--- rollback SELECT 1; -- prices may have been edited; keep them
+-- rollback empty
 
 -- changeset qbit-assistant:defaults-10
 -- preconditions onFail:MARK_RAN onError:MARK_RAN
@@ -156,4 +159,4 @@ SELECT 'Example: weekly change summary', FALSE,
    CURRENT_TIMESTAMP, CURRENT_TIMESTAMP
 FROM (SELECT MIN(id) AS id FROM assistant_profile WHERE name = 'default') p
 WHERE NOT EXISTS (SELECT 1 FROM assistant_scheduled_task WHERE name = 'Example: weekly change summary');
--- rollback DELETE FROM assistant_scheduled_task WHERE name = 'Example: weekly change summary' AND enabled = FALSE;
+-- rollback empty

qbit-assistant/src/main/resources/openapi/qqq-v1/assistant.yaml

@@ -53,6 +53,43 @@ components:
           nullable: true
           type: "string"
       type: "object"
+    AssistantActiveTurnsResponseV1:
+      description: "The caller's active runs, newest first; stale leases are reaped."
+      properties:
+        turns:
+          items:
+            description: "An active assistant run."
+            properties:
+              turnId:
+                type: "integer"
+              conversationId:
+                type: "integer"
+              assistantMessageId:
+                type: "integer"
+              userMessageId:
+                type: "integer"
+              status:
+                description: "RUNNING or CANCELLING."
+                type: "string"
+              phase:
+                type: "string"
+              startedAt:
+                description: "ISO-8601."
+                type: "string"
+              heartbeatAt:
+                description: "ISO-8601."
+                type: "string"
+              elapsedMs:
+                type: "integer"
+              live:
+                description: "Running on this replica."
+                type: "boolean"
+              concurrencyMode:
+                description: "SUPERSEDE or CONCURRENT."
+                type: "string"
+            type: "object"
+          type: "array"
+      type: "object"
     AssistantConfigResponseV1:
       description: "Whether the assistant is available to this user, and how."
       properties:
@@ -187,8 +224,8 @@ components:
       type: "object"
     AssistantTurnEventV1:
       description: "One server-sent event of a turn (event: <type>, id: <seq>, data:\
-        \ this object). Types: message.start, text.delta, tool.start, tool.result,\
-        \ ui.navigate, notice, usage, message.end, error, ping."
+        \ this object). Types: message.start, turn.phase, text.delta, tool.start,\
+        \ tool.result, ui.navigate, notice, usage, message.end, error, ping."
       properties:
         seq:
           description: "Sequence number; resume with ?after=<seq>."
@@ -198,7 +235,9 @@ components:
           type: "string"
         data:
           additionalProperties: true
-          description: "The event's fields, by type."
+          description: "The event's fields, by type. message.start includes startedAt\
+            \ (ISO-8601). turn.phase includes phase (thinking, tool, writing), optional\
+            \ toolName and label."
           type: "object"
       type: "object"
   securitySchemes:
@@ -212,7 +251,7 @@ info:
   description: "QQQ Assistant: conversations, streamed turns, feedback, pending actions\
     \ and data access explanations"
   title: "QQQ Middleware API extension: assistant"
-  version: "1.1.0"
+  version: "1.2.0"
 openapi: "3.0.3"
 paths:
   /qqq/v1/assistant/config:
@@ -605,6 +644,10 @@ paths:
                   additionalProperties: true
                   description: "Where the user is in the app."
                   type: "object"
+                concurrency:
+                  description: "supersede or concurrent (case-insensitive); defaults\
+                    \ to the host configuration."
+                  type: "string"
               type: "object"
         required: true
       responses:
@@ -754,6 +797,12 @@ paths:
               schema:
                 $ref: "#/components/schemas/AssistantErrorV1"
           description: "Disabled, not configured, or the kill switch is on"
+        200:
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/AssistantStatusResponseV1"
+          description: "Successful Response"
         409:
           content:
             application/json:
@@ -765,7 +814,7 @@ paths:
             application/json:
               schema:
                 $ref: "#/components/schemas/AssistantStatusResponseV1"
-          description: "Successful Response"
+          description: "Legacy replica: cancellation accepted"
         429:
           content:
             application/json:
@@ -776,6 +825,56 @@ paths:
       - sessionUuidCookie:
         - "N/A"
       summary: "Stop a running turn"
+  /qqq/v1/assistant/turns/active:
+    get:
+      description: "Find the user's active assistant runs"
+      responses:
+        400:
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/AssistantErrorV1"
+          description: "Invalid input"
+        403:
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/AssistantErrorV1"
+          description: "No access to the assistant"
+        404:
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/AssistantErrorV1"
+          description: "Not found (or not the user's own)"
+        503:
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/AssistantErrorV1"
+          description: "Disabled, not configured, or the kill switch is on"
+        200:
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/AssistantActiveTurnsResponseV1"
+          description: "Successful Response"
+        409:
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/AssistantErrorV1"
+          description: "Already finished or decided"
+        429:
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/AssistantErrorV1"
+          description: "Budget or rate limit"
+      security:
+      - sessionUuidCookie:
+        - "N/A"
+      summary: "Find the user's active assistant runs"
   /qqq/v1/assistant/messages/{id}/feedback:
     post:
       description: "Thumbs up or down on an assistant message"

qbit-assistant/src/test/java/com/kingsrook/qbits/assistant/AssistantDefaultsChangelogTest.java

@@ -144,6 +144,33 @@ class AssistantDefaultsChangelogTest extends BaseAssistantTest
 
 
 
+   /*******************************************************************************
+    ** Rolling the changelog back never deletes data: not the host's own rows
+    ** (changesets marked ran included), not the seeded ones.
+    *******************************************************************************/
+   @Test
+   void rollbackKeepsEveryRow() throws Exception
+   {
+      try(Connection connection = freshSchema(); Statement statement = connection.createStatement())
+      {
+         statement.execute("INSERT INTO assistant_policy (name, kill_switch) VALUES ('default', FALSE)");
+         statement.execute("INSERT INTO assistant_profile (name, display_name, is_default, enabled) VALUES ('default', 'Hal', TRUE, TRUE)");
+         statement.execute("INSERT INTO assistant_skill (name, instructions) VALUES ('find-and-count', 'The host wrote this.')");
+         runChangelog(connection);
+         Map<String, Integer> before = counts(connection);
+
+         Database database = DatabaseFactory.getInstance().findCorrectDatabaseImplementation(new JdbcConnection(connection));
+         new Liquibase(CHANGELOG.substring(1), new ClassLoaderResourceAccessor(), database).rollback(10, (String) null);
+
+         assertThat(ranChangesets(connection)).isEmpty();
+         assertThat(counts(connection)).isEqualTo(before);
+         assertThat(scalar(connection, "SELECT display_name FROM assistant_profile WHERE name = 'default'")).isEqualTo("Hal");
+         assertThat(scalar(connection, "SELECT instructions FROM assistant_skill WHERE name = 'find-and-count'")).isEqualTo("The host wrote this.");
+      }
+   }
+
+
+
    /*******************************************************************************
     ** A host without one of the tables: that changeset is marked ran, the
     ** rest apply, nothing fails.
@@ -174,7 +201,7 @@ class AssistantDefaultsChangelogTest extends BaseAssistantTest
       for(String changeset : changesets)
       {
          assertThat(changeset).contains("-- preconditions onFail:MARK_RAN onError:MARK_RAN").contains("-- precondition-sql-check expectedResult:0 ")
-            .doesNotContain("precondition-table-exists").contains("-- rollback ").contains("NOT EXISTS");
+            .doesNotContain("precondition-table-exists").contains("-- rollback empty").contains("NOT EXISTS");
       }
       for(String table : SEEDED_TABLES)
       {
@@ -318,6 +345,11 @@ class AssistantDefaultsChangelogTest extends BaseAssistantTest
       {
          for(String sql : statements(ddl))
          {
+            if(sql.startsWith("DO $$"))
+            {
+               // the foreign-key block is PL/pgSQL (Postgres only); SchemaForeignKeyPostgresTest runs it on real Postgres
+               continue;
+            }
             Matcher m = Pattern.compile("^(CREATE TABLE|ALTER TABLE) (assistant_[a-z_]+)\\b(.*)", Pattern.DOTALL).matcher(sql);
             if(m.find() && DDL_TABLES.contains(m.group(2)) && (m.group(1).startsWith("CREATE") || m.group(3).strip().startsWith("ADD COLUMN")))
             {
@@ -393,7 +425,8 @@ class AssistantDefaultsChangelogTest extends BaseAssistantTest
 
 
    /*******************************************************************************
-    ** SQL statements, without comment lines, split at a ';' that ends a line.
+    ** SQL statements, without comment lines, split at a ';' that ends a line;
+    ** a DO $$ ... $$ block stays one statement.
     *******************************************************************************/
    static List<String> statements(String sql)
    {
@@ -406,14 +439,36 @@ class AssistantDefaultsChangelogTest extends BaseAssistantTest
             text.append(stripped).append("\n");
          }
       }
-      List<String> rs = new ArrayList<>();
+      List<String>  rs    = new ArrayList<>();
+      StringBuilder block = null;
       for(String statement : text.toString().split(";\\s*\\n"))
       {
+         String stripped = statement.strip();
+         if(block == null && stripped.startsWith("DO $$") && !stripped.endsWith("$$"))
+         {
+            // a dollar-quoted block has its own semicolons: keep it whole up to its closing $$
+            block = new StringBuilder(stripped);
+            continue;
+         }
+         if(block != null)
+         {
+            block.append(";\n").append(stripped);
+            if(stripped.endsWith("$$"))
+            {
+               rs.add(block.toString());
+               block = null;
+            }
+            continue;
+         }
          if(!statement.isBlank())
          {
-            rs.add(statement.strip().replaceAll(";$", ""));
+            rs.add(stripped.replaceAll(";$", ""));
          }
       }
+      if(block != null)
+      {
+         rs.add(block.toString());
+      }
       return (rs);
    }
 

qbit-assistant/src/test/java/com/kingsrook/qbits/assistant/api/AssistantRouteProviderTest.java

@@ -30,9 +30,13 @@ import java.util.ArrayList;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.TimeUnit;
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.kingsrook.qbits.assistant.model.AssistantPolicy;
 import com.kingsrook.qbits.assistant.persistence.AssistantStore;
+import com.kingsrook.qbits.assistant.spi.ModelPart;
+import com.kingsrook.qbits.assistant.spi.ModelResponse;
 import com.kingsrook.qbits.assistant.testing.AssistantTestFixture;
 import com.kingsrook.qbits.assistant.testing.BaseAssistantTest;
 import com.kingsrook.qbits.assistant.testing.UiApiTestServer;
@@ -314,7 +318,7 @@ class AssistantRouteProviderTest extends BaseAssistantTest
       assertThat(send("POST", "/messages/" + messages.get(0).get("id") + "/feedback", EDITOR, "{\"rating\":1}").statusCode()).isEqualTo(400);
       assertThat(send("POST", "/messages/" + msgId + "/feedback", OTHER_EDITOR, "{\"rating\":-1}").statusCode()).isEqualTo(404);
 
-      assertThat(send("POST", "/turns/" + turnId + "/cancel", EDITOR, "{}").statusCode()).isEqualTo(409);
+      assertThat(send("POST", "/turns/" + turnId + "/cancel", EDITOR, "{}").statusCode()).isEqualTo(200);
    }
 
 
@@ -351,15 +355,10 @@ class AssistantRouteProviderTest extends BaseAssistantTest
       }
       assertThat(turnId).isNotNull();
 
-      ///////////////////////////////////////////////////////////////
-      // a second turn while one runs: refused (concurrency = 1)  //
-      ///////////////////////////////////////////////////////////////
-      assertThat(send("POST", "/conversations/" + id + "/turns", EDITOR, "{\"text\":\"again\"}").statusCode()).isEqualTo(429);
-
       Thread.sleep(500);
       assertThat(send("POST", "/turns/" + turnId + "/cancel", OTHER_EDITOR, "{}").statusCode()).isEqualTo(404);
       HttpResponse<String> cancel = send("POST", "/turns/" + turnId + "/cancel", EDITOR, "{}");
-      assertThat(cancel.statusCode()).isEqualTo(202);
+      assertThat(cancel.statusCode()).isEqualTo(200);
       assertThat(json(cancel)).containsEntry("status", "CANCELLING");
 
       List<Frame> frames = frames(future.get().body());
@@ -371,6 +370,96 @@ class AssistantRouteProviderTest extends BaseAssistantTest
 
 
 
+   /*******************************************************************************
+    ** A disconnected POST keeps running; active discovery and replay can attach
+    ** again while the answer is blocked, then receive the terminal frame.
+    *******************************************************************************/
+   @Test
+   @SuppressWarnings("unchecked")
+   void testDisconnectRefreshAndReattach() throws Exception
+   {
+      CountDownLatch entered = new CountDownLatch(1);
+      CountDownLatch release = new CountDownLatch(1);
+      provider.thenToolUses("I am checking the count before answering. ", List.<Object[]>of(new Object[] { "count_records", Map.of("table", "blog_post") }))
+         .thenRespond(request ->
+         {
+            entered.countDown();
+            try
+            {
+               if(!release.await(5, TimeUnit.SECONDS))
+               {
+                  throw (new IllegalStateException("test did not release provider"));
+               }
+            }
+            catch(InterruptedException e)
+            {
+               Thread.currentThread().interrupt();
+            }
+            return (new ModelResponse().withParts(List.of(ModelPart.text("Finished after reconnect."))).withStopReason(ModelResponse.STOP_END_TURN));
+         });
+      Integer conversation = (Integer) json(send("POST", "/conversations", EDITOR, "{}")).get("id");
+      HttpRequest request = HttpRequest.newBuilder(URI.create(base + "/conversations/" + conversation + "/turns"))
+         .header("Cookie", "sessionId=" + EDITOR).header("Content-Type", "application/json")
+         .POST(HttpRequest.BodyPublishers.ofString("{\"text\":\"count posts\"}")).build();
+      int lastSeq = 0;
+      try
+      {
+         HttpResponse<InputStream> response = client.send(request, HttpResponse.BodyHandlers.ofInputStream());
+         assertThat(response.statusCode()).isEqualTo(200);
+         try(BufferedReader reader = new BufferedReader(new InputStreamReader(response.body(), StandardCharsets.UTF_8)))
+         {
+            String event = null;
+            String line;
+            while((line = reader.readLine()) != null)
+            {
+               if(line.startsWith("id: "))
+               {
+                  lastSeq = Integer.parseInt(line.substring(4));
+               }
+               if(line.startsWith("event: "))
+               {
+                  event = line.substring(7);
+               }
+               if(line.isEmpty() && "text.delta".equals(event))
+               {
+                  break;
+               }
+            }
+         }
+         assertThat(lastSeq).isPositive();
+         assertThat(entered.await(5, TimeUnit.SECONDS)).isTrue();
+         HttpResponse<String> activeResponse = send("GET", "/turns/active", EDITOR, null);
+         assertThat(activeResponse.statusCode()).isEqualTo(200);
+         List<Map<String, Object>> active = (List<Map<String, Object>>) json(activeResponse).get("turns");
+         assertThat(active).hasSize(1);
+         Map<String, Object> turn = active.getFirst();
+         assertThat(turn).containsEntry("live", true).containsEntry("phase", "thinking").containsEntry("conversationId", conversation)
+            .containsKeys("startedAt", "heartbeatAt", "elapsedMs", "concurrencyMode");
+         assertThat(json(send("GET", "/turns/active", OTHER_EDITOR, null)).get("turns")).isEqualTo(List.of());
+         assertThat(send("GET", "/turns/active", NO_ACCESS, null).statusCode()).isEqualTo(403);
+         HttpRequest attach = HttpRequest.newBuilder(URI.create(base + "/turns/" + turn.get("turnId") + "/events?after=0"))
+            .header("Cookie", "sessionId=" + EDITOR).GET().build();
+         HttpResponse<InputStream> attached = client.send(attach, HttpResponse.BodyHandlers.ofInputStream());
+         release.countDown();
+         List<Frame> followed = frames(attached.body());
+         assertThat(followed.getFirst().event()).isEqualTo("message.start");
+         assertThat(followed.getFirst().data()).containsKey("startedAt");
+         assertThat(followed.getLast().event()).isEqualTo("message.end");
+         assertThat(followed.getLast().data()).containsEntry("status", "COMPLETE");
+         HttpRequest replay = HttpRequest.newBuilder(URI.create(base + "/turns/" + turn.get("turnId") + "/events?after=" + lastSeq))
+            .header("Cookie", "sessionId=" + EDITOR).GET().build();
+         List<Frame> rest = frames(client.send(replay, HttpResponse.BodyHandlers.ofInputStream()).body());
+         assertThat(Integer.parseInt(rest.getFirst().id())).isEqualTo(lastSeq + 1);
+         assertThat(rest.getLast().event()).isEqualTo("message.end");
+      }
+      finally
+      {
+         release.countDown();
+      }
+   }
+
+
+
    /*******************************************************************************
     **
     *******************************************************************************/

qbit-assistant/src/test/java/com/kingsrook/qbits/assistant/engine/DurableTurnsTest.java

@@ -0,0 +1,902 @@
+/*
+ * Copyright 2026 Kingsrook, LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.kingsrook.qbits.assistant.engine;
+
+
+import java.time.Clock;
+import java.time.Duration;
+import java.time.Instant;
+import java.time.LocalDate;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.function.BooleanSupplier;
+import com.kingsrook.qbits.assistant.AssistantQBitConfig;
+import com.kingsrook.qbits.assistant.AssistantRuntime;
+import com.kingsrook.qbits.assistant.api.AssistantApi;
+import com.kingsrook.qbits.assistant.api.AssistantApiException;
+import com.kingsrook.qbits.assistant.jobs.AssistantRunTracker;
+import com.kingsrook.qbits.assistant.model.AssistantConversation;
+import com.kingsrook.qbits.assistant.model.AssistantMessage;
+import com.kingsrook.qbits.assistant.model.AssistantTurn;
+import com.kingsrook.qbits.assistant.persistence.AssistantStore;
+import com.kingsrook.qbits.assistant.provider.fake.ScriptedModelProvider;
+import com.kingsrook.qbits.assistant.spi.ModelEventListener;
+import com.kingsrook.qbits.assistant.spi.ModelPart;
+import com.kingsrook.qbits.assistant.spi.ModelRequest;
+import com.kingsrook.qbits.assistant.spi.ModelResponse;
+import com.kingsrook.qbits.assistant.spi.ModelUsage;
+import com.kingsrook.qbits.assistant.spi.StreamHandle;
+import com.kingsrook.qbits.assistant.testing.AssistantTestFixture;
+import com.kingsrook.qbits.assistant.testing.BaseAssistantTest;
+import com.kingsrook.qqq.backend.core.context.QContext;
+import com.kingsrook.qqq.backend.core.exceptions.QException;
+import com.kingsrook.qqq.backend.core.model.actions.tables.query.QQueryFilter;
+import com.kingsrook.qqq.backend.core.model.data.QRecord;
+import com.kingsrook.qqq.backend.core.model.data.QRecordEntity;
+import com.kingsrook.qqq.backend.core.model.session.QSession;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import static com.kingsrook.qbits.assistant.testing.AssistantTestFixture.EDITOR;
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+
+/*******************************************************************************
+ ** Durable run lifecycle, using latches instead of provider timing guesses.
+ *******************************************************************************/
+class DurableTurnsTest extends BaseAssistantTest
+{
+   private QSession session;
+   private AssistantApi api;
+   private AssistantStore store;
+
+
+
+   /*******************************************************************************
+    ** Short, valid lease settings keep watchdog tests bounded.
+    *******************************************************************************/
+   @Override
+   protected void customizeConfig(AssistantQBitConfig config)
+   {
+      config.withTurnHeartbeatSeconds(1).withTurnLeaseSeconds(3).withTurnForceFinalizeGraceSeconds(1)
+         .withMaxTurnSeconds(10).withKillSwitchPollMillis(50);
+   }
+
+
+
+   /*******************************************************************************
+    ** Every operation uses the user's own fixture session.
+    *******************************************************************************/
+   @BeforeEach
+   void atomicBackend()
+   {
+      config.getRuntime().close();
+      config.setRuntime(new AssistantRuntime(qInstance, config, Clock.systemUTC(), new AtomicCallsStore(config)));
+      userContext();
+   }
+
+
+
+   /*******************************************************************************
+    ** Establish the caller's context, also after a test replaces the runtime.
+    *******************************************************************************/
+   private void userContext()
+   {
+      session = AssistantTestFixture.ownerSession(EDITOR, config);
+      QContext.init(qInstance, session);
+      api = new AssistantApi(config.getRuntime(), session);
+      store = config.getRuntime().getStore();
+   }
+
+
+
+   /*******************************************************************************
+    ** Completion closes the lease, emits progress, and frees the next question.
+    *******************************************************************************/
+   @Test
+   void completion() throws Exception
+   {
+      provider.thenText("Done").thenText("Again");
+      Integer conversation = conversation();
+      RunningTurn first = api.startTurn(conversation, Map.of("text", "hello"));
+      AssistantTurn row = completed(first);
+      assertThat(row.getStatus()).isEqualTo("COMPLETE");
+      assertThat(row.getPhase()).isEqualTo("done");
+      assertThat(row.getEndedAt()).isNotNull();
+      assertThat(row.getHeartbeatAt()).isAfterOrEqualTo(row.getStartedAt());
+      assertThat(row.getLeaseOwner()).isEqualTo(config.getRuntime().getInstanceId()).hasSizeLessThanOrEqualTo(100);
+      assertThat(row.getConcurrencyMode()).isEqualTo("SUPERSEDE");
+      assertThat(store.listRunningTurns(EDITOR)).isEmpty();
+      assertThat(store.updateRunningTurn(EDITOR, new QRecord().withValue("id", first.getTurnId()).withValue("status", "CANCELLING"))).isFalse();
+      assertThat(first.getLog().after(0, 1).getFirst().getData()).containsEntry("startedAt", row.getStartedAt().toString());
+      assertThat(first.getLog().after(0, 1)).filteredOn(e -> TurnEvent.TURN_PHASE.equals(e.getType()))
+         .extracting(e -> e.getData().get("phase")).containsExactly("thinking", "writing");
+      assertThat(completed(api.startTurn(conversation, Map.of("text", "again"))).getStatus()).isEqualTo("COMPLETE");
+   }
+
+
+
+   /*******************************************************************************
+    ** A throwing post-processing collaborator cannot strand a streamed answer.
+    *******************************************************************************/
+   @Test
+   void accountingFailureStillFinalizes() throws Exception
+   {
+      AssistantStore failing = new AssistantStore(config)
+      {
+         /*******************************************************************************
+          ** Inject a failure after streaming has finished.
+          *******************************************************************************/
+         @Override
+         public void addUsage(String userId, LocalDate date, ModelUsage usage, long costMicros, boolean countTurn)
+         {
+            throw (new IllegalStateException("accounting unavailable"));
+         }
+
+         /*******************************************************************************
+          ** Conversation totals fail independently of the turn update.
+          *******************************************************************************/
+         @Override
+         public void updateFields(String table, QRecord record) throws QException
+         {
+            if(AssistantConversation.TABLE_NAME.equals(table) && record.getValue("totalTokensIn") != null)
+            {
+               throw (new IllegalStateException("totals unavailable"));
+            }
+            super.updateFields(table, record);
+         }
+      };
+      config.getRuntime().close();
+      AssistantRuntime runtime = new AssistantRuntime(qInstance, config, Clock.systemUTC())
+      {
+         /*******************************************************************************
+          ** Substitute only the engine/API persistence collaborator.
+          *******************************************************************************/
+         @Override
+         public AssistantStore getStore()
+         {
+            return (failing);
+         }
+      };
+      config.setRuntime(runtime);
+      userContext();
+      provider.thenText("A streamed answer").thenText("Next answer");
+      Integer conversation = conversation();
+      RunningTurn run = api.startTurn(conversation, Map.of("text", "hello"));
+      assertThat(completed(run).getStatus()).isEqualTo("COMPLETE");
+      assertThat(api.turnEvents(run.getTurnId(), 0).persisted()).extracting(TurnEvent::getType).contains(TurnEvent.TEXT_DELTA, TurnEvent.MESSAGE_END);
+      assertThat(completed(api.startTurn(conversation, Map.of("text", "next"))).getStatus()).isEqualTo("COMPLETE");
+   }
+
+
+
+   /*******************************************************************************
+    ** Explicit concurrent mode permits overlap within and across conversations.
+    *******************************************************************************/
+   @Test
+   void concurrentQuestions() throws Exception
+   {
+      ControlledProvider controlled = controlled(false);
+      Integer firstConversation = conversation();
+      List<RunningTurn> runs = new ArrayList<>();
+      runs.add(api.startTurn(firstConversation, Map.of("text", "one", "concurrency", "CoNcUrReNt")));
+      controlled.awaitCalls(1);
+      runs.add(api.startTurn(firstConversation, Map.of("text", "two", "concurrency", "concurrent")));
+      controlled.awaitCalls(2);
+      runs.add(api.startTurn(conversation(), Map.of("text", "three", "concurrency", "concurrent")));
+      controlled.awaitCalls(3);
+      assertThat(active()).hasSize(3);
+      controlled.release();
+      for(RunningTurn run : runs)
+      {
+         assertThat(completed(run).getStatus()).isEqualTo("COMPLETE");
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** Default supersede frees the slot immediately and records the explanation.
+    *******************************************************************************/
+   @Test
+   void supersedeAndSoftCap() throws Exception
+   {
+      ControlledProvider controlled = controlled(false);
+      Integer conversation = conversation();
+      RunningTurn first = api.startTurn(conversation, Map.of("text", "one"));
+      controlled.awaitCalls(1);
+      RunningTurn second = api.startTurn(conversation, Map.of("text", "two"));
+      controlled.awaitCalls(2);
+      AssistantTurn superseded = completed(first);
+      assertThat(superseded.getStatus()).isEqualTo("CANCELLED");
+      assertThat(superseded.getCancelReason()).isEqualTo("SUPERSEDED");
+      assertThat(store.getMessage(EDITOR, superseded.getAssistantMessageId()).getPartsJson()).contains(TurnEngine.SUPERSEDED_TEXT);
+      config.setMaxConcurrentTurnsPerUser(2);
+      RunningTurn third = api.startTurn(conversation(), Map.of("text", "three", "concurrency", "concurrent"));
+      controlled.awaitCalls(3);
+      RunningTurn fourth = api.startTurn(conversation(), Map.of("text", "four", "concurrency", "concurrent"));
+      controlled.awaitCalls(4);
+      assertThat(completed(second).getCancelReason()).isEqualTo("SUPERSEDED");
+      controlled.release();
+      assertThat(completed(third).getStatus()).isEqualTo("COMPLETE");
+      assertThat(completed(fourth).getStatus()).isEqualTo("COMPLETE");
+   }
+
+
+
+   /*******************************************************************************
+    ** A provider ignoring both cancel and interruption is forcibly finalized.
+    *******************************************************************************/
+   @Test
+   void wedgedProviderTimeout() throws Exception
+   {
+      ControlledProvider controlled = controlled(true);
+      controlled.emitText = false;
+      RecordingTracker tracker = new RecordingTracker();
+      config.setRunTracker(tracker);
+      config.setMaxTurnSeconds(1);
+      RunningTurn run = api.startTurn(conversation(), Map.of("text", "wedged"));
+      try
+      {
+         controlled.awaitCalls(1);
+         AssistantTurn row = completed(run);
+         assertThat(row.getStatus()).isEqualTo("ERROR");
+         assertThat(row.getErrorCode()).isEqualTo("TIMEOUT");
+         assertThat(row.getCancelReason()).isEqualTo("TIMEOUT");
+         assertThat(store.getMessage(EDITOR, row.getAssistantMessageId()).getPartsJson()).contains(TurnEngine.TIMEOUT_TEXT);
+         assertThat(controlled.handles.getFirst().cancelled).isTrue();
+         assertThat(tracker.finishes.get()).isEqualTo(1);
+         int events = run.getLog().after(0, 1).size();
+         controlled.release();
+         await(() -> controlled.handles.getFirst().returned);
+         assertThat(run.getLog().after(0, 1)).hasSize(events);
+         assertThat(tracker.finishes.get()).isEqualTo(1);
+      }
+      finally
+      {
+         controlled.release();
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** Stop has its own bounded force path even when the provider ignores it.
+    *******************************************************************************/
+   @Test
+   void stopWedgedProvider() throws Exception
+   {
+      ControlledProvider controlled = controlled(true);
+      RunningTurn run = api.startTurn(conversation(), Map.of("text", "wait"));
+      try
+      {
+         controlled.awaitCalls(1);
+         assertThat(api.cancelTurn(run.getTurnId())).containsEntry("status", "CANCELLING");
+         AssistantTurn row = completed(run);
+         assertThat(row.getStatus()).isEqualTo("CANCELLED");
+         assertThat(row.getCancelReason()).isEqualTo("USER");
+      }
+      finally
+      {
+         controlled.release();
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** A failed heartbeat tick does not stop cancellation polling on later ticks.
+    *******************************************************************************/
+   @Test
+   void heartbeatFailureDoesNotKillWatchdog() throws Exception
+   {
+      AtomicInteger heartbeats = new AtomicInteger();
+      AssistantStore failingOnce = new AssistantStore(config)
+      {
+         /*******************************************************************************
+          ** Fail only the first renewal, then behave like the real store.
+          *******************************************************************************/
+         @Override
+         public void updateFields(String table, QRecord record) throws QException
+         {
+            if(AssistantTurn.TABLE_NAME.equals(table) && record.getValue("heartbeatAt") != null && heartbeats.incrementAndGet() == 1)
+            {
+               throw (new QException("temporary heartbeat failure"));
+            }
+            super.updateFields(table, record);
+         }
+      };
+      config.getRuntime().close();
+      config.setRuntime(new AssistantRuntime(qInstance, config)
+      {
+         /*******************************************************************************
+          ** A transient persistence failure local to the owner.
+          *******************************************************************************/
+         @Override
+         public AssistantStore getStore()
+         {
+            return (failingOnce);
+         }
+      });
+      userContext();
+      ControlledProvider controlled = controlled(false);
+      RunningTurn run = api.startTurn(conversation(), Map.of("text", "wait"));
+      controlled.awaitCalls(1);
+      AssistantRuntime other = new AssistantRuntime(qInstance, config);
+      try
+      {
+         new AssistantApi(other, session).cancelTurn(run.getTurnId());
+         assertThat(completed(run).getStatus()).isEqualTo("CANCELLED");
+         assertThat(heartbeats.get()).isGreaterThanOrEqualTo(2);
+      }
+      finally
+      {
+         controlled.release();
+         other.close();
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** Stale leases, old cancel requests and absolute deadlines release remotely.
+    *******************************************************************************/
+   @Test
+   void orphanRecoveryAndIdempotentStop() throws Exception
+   {
+      AssistantTurn stale = remote(Instant.now().minusSeconds(5));
+      AssistantTurn fresh = remote(Instant.now());
+      AssistantTurn deadline = remote(Instant.now());
+      store.updateFields(AssistantTurn.TABLE_NAME, new QRecord().withValue("id", deadline.getId()).withValue("startedAt", Instant.now().minusSeconds(30)));
+      assertThat(active()).extracting(r -> r.get("turnId")).containsExactly(fresh.getId());
+      assertThat(store.getTurn(EDITOR, stale.getId()).getStatus()).isEqualTo("ERROR");
+      assertThat(store.getTurn(EDITOR, deadline.getId()).getStatus()).isEqualTo("ERROR");
+      assertThat(api.turnEvents(stale.getId(), 0).persisted()).extracting(TurnEvent::getType).containsExactly(TurnEvent.ERROR, TurnEvent.MESSAGE_END);
+      assertThat(api.turnEvents(stale.getId(), 0).persisted()).hasSize(2);
+      assertThat(api.cancelTurn(stale.getId())).containsEntry("status", "ERROR");
+      assertThat(api.cancelTurn(fresh.getId())).containsEntry("status", "CANCELLING");
+      assertThat(store.getTurn(EDITOR, fresh.getId()).getCancelRequestedAt()).isNotNull();
+      store.updateFields(AssistantTurn.TABLE_NAME, new QRecord().withValue("id", fresh.getId()).withValue("cancelRequestedAt", Instant.now().minusSeconds(5)));
+      assertThat(active()).isEmpty();
+      assertThat(store.getTurn(EDITOR, fresh.getId()).getStatus()).isEqualTo("CANCELLED");
+      AssistantTurn stopped = remote(Instant.now().minusSeconds(5));
+      assertThat(api.cancelTurn(stopped.getId())).containsEntry("status", "CANCELLED");
+      assertThat(api.cancelTurn(stopped.getId())).containsEntry("status", "CANCELLED");
+      provider.thenText("Recovered");
+      assertThat(completed(api.startTurn(conversation(), Map.of("text", "next"))).getStatus()).isEqualTo("COMPLETE");
+   }
+
+
+
+   /*******************************************************************************
+    ** Two replicas reaping the same row produce only one terminal frame.
+    *******************************************************************************/
+   @Test
+   void simultaneousReapers() throws Exception
+   {
+      AssistantTurn stale = remote(Instant.now().minusSeconds(5));
+      AssistantRuntime other = new AssistantRuntime(qInstance, config);
+      CountDownLatch start = new CountDownLatch(1);
+      try(var executor = java.util.concurrent.Executors.newVirtualThreadPerTaskExecutor())
+      {
+         List<java.util.concurrent.Future<?>> futures = new ArrayList<>();
+         for(AssistantRuntime runtime : List.of(config.getRuntime(), other))
+         {
+            futures.add(executor.submit(() ->
+            {
+               start.await();
+               QContext.init(qInstance, session);
+               try
+               {
+                  new AssistantApi(runtime, session).activeTurns();
+               }
+               finally
+               {
+                  QContext.clear();
+               }
+               return (null);
+            }));
+         }
+         start.countDown();
+         for(var future : futures)
+         {
+            future.get(5, java.util.concurrent.TimeUnit.SECONDS);
+         }
+         List<TurnEvent> events = api.turnEvents(stale.getId(), 0).persisted();
+         assertThat(events).filteredOn(TurnEvent::isTerminal).hasSize(1);
+         assertThat(store.getTurn(EDITOR, stale.getId()).getStatus()).isEqualTo("ERROR");
+      }
+      finally
+      {
+         other.close();
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** A terminal outcome written elsewhere wins over the local engine's finish.
+    *******************************************************************************/
+   @Test
+   void remoteTerminalOutcomeIsPreserved() throws Exception
+   {
+      ControlledProvider controlled = controlled(false);
+      RunningTurn run = api.startTurn(conversation(), Map.of("text", "wait"));
+      controlled.awaitCalls(1);
+      store.insertEvent(run.getTurnId(), EDITOR, 50, TurnEvent.MESSAGE_END,
+         new TurnEvent(50, TurnEvent.MESSAGE_END, Map.of("status", "ERROR", "stopReason", "interrupted")).toJson());
+      store.updateFields(AssistantTurn.TABLE_NAME, new QRecord().withValue("id", run.getTurnId()).withValue("status", "ERROR")
+         .withValue("phase", "done").withValue("errorCode", "INTERNAL").withValue("stopReason", "interrupted").withValue("endedAt", Instant.now()));
+      controlled.release();
+      assertThat(completed(run).getStatus()).isEqualTo("ERROR");
+      assertThat(api.turnEvents(run.getTurnId(), 0).persisted()).filteredOn(TurnEvent::isTerminal).hasSize(1);
+      assertThat(run.getLog().after(0, 1)).last().extracting(e -> e.getData().get("status")).isEqualTo("ERROR");
+   }
+
+
+
+   /*******************************************************************************
+    ** Configuration rejects invalid lease timing and concurrency modes.
+    *******************************************************************************/
+   @Test
+   void configurationValidation()
+   {
+      config.withTurnHeartbeatSeconds(5).withTurnLeaseSeconds(4).withDefaultConcurrencyMode("invalid");
+      List<String> errors = new ArrayList<>();
+      config.validate(qInstance, errors);
+      assertThat(errors).contains("turnHeartbeatSeconds must be less than turnLeaseSeconds.", "defaultConcurrencyMode must be SUPERSEDE or CONCURRENT.");
+      config.withRunTracker(null);
+      assertThat(config.getRunTracker()).isSameAs(AssistantRunTracker.NOOP);
+   }
+
+
+
+   /*******************************************************************************
+    ** A different runtime writes Stop; the owner sees it within one heartbeat.
+    *******************************************************************************/
+   @Test
+   void crossPodStopAndHeartbeat() throws Exception
+   {
+      ControlledProvider controlled = controlled(false);
+      RunningTurn run = api.startTurn(conversation(), Map.of("text", "wait"));
+      controlled.awaitCalls(1);
+      AssistantRuntime remote = new AssistantRuntime(qInstance, config);
+      try
+      {
+         assertThat(remote.getInstanceId()).isNotEqualTo(config.getRuntime().getInstanceId());
+         AssistantApi otherPod = new AssistantApi(remote, session);
+         assertThat(((List<?>) otherPod.activeTurns().get("turns"))).hasSize(1);
+         assertThat(active().getFirst()).containsEntry("live", true).containsEntry("phase", "writing").containsKey("elapsedMs");
+         assertThat(otherPod.cancelTurn(run.getTurnId())).containsEntry("status", "CANCELLING");
+         AssistantTurn row = completed(run);
+         assertThat(row.getStatus()).isEqualTo("CANCELLED");
+         assertThat(row.getCancelReason()).isEqualTo("USER");
+         assertThat(row.getHeartbeatAt()).isAfter(row.getStartedAt());
+         assertThat(otherPod.cancelTurn(run.getTurnId())).containsEntry("status", "CANCELLED");
+      }
+      finally
+      {
+         controlled.release();
+         remote.close();
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** Shutdown force-finalizes a wedged engine and refuses new inserts with 503.
+    *******************************************************************************/
+   @Test
+   void rollingDeploy() throws Exception
+   {
+      ControlledProvider controlled = controlled(true);
+      RecordingTracker tracker = new RecordingTracker();
+      config.setRunTracker(tracker);
+      Integer conversation = conversation();
+      RunningTurn run = api.startTurn(conversation, Map.of("text", "wait"));
+      try
+      {
+         controlled.awaitCalls(1);
+         config.getRuntime().shutdown(Duration.ZERO);
+         QContext.init(qInstance, session);
+         AssistantTurn row = completed(run);
+         assertThat(row.getStatus()).isEqualTo("ERROR");
+         assertThat(row.getErrorCode()).isEqualTo("INTERRUPTED");
+         assertThat(store.getMessage(EDITOR, row.getAssistantMessageId()).getPartsJson()).contains(TurnEngine.RESTART_TEXT);
+         assertThat(tracker.finishes.get()).isEqualTo(1);
+         int messages = store.listMessages(EDITOR, conversation, null, 100).size();
+         assertThatThrownBy(() -> api.startTurn(conversation, Map.of("text", "retry")))
+            .isInstanceOfSatisfying(AssistantApiException.class, e ->
+            {
+               assertThat(e.getStatus()).isEqualTo(503);
+               assertThat(e.getCode()).isEqualTo("SHUTTING_DOWN");
+            });
+         assertThat(store.listMessages(EDITOR, conversation, null, 100)).hasSize(messages);
+      }
+      finally
+      {
+         controlled.release();
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** Graceful cancellation also uses the restart outcome, not a user cancel.
+    *******************************************************************************/
+   @Test
+   void gracefulShutdown() throws Exception
+   {
+      ControlledProvider controlled = controlled(false);
+      RunningTurn run = api.startTurn(conversation(), Map.of("text", "wait"));
+      controlled.awaitCalls(1);
+      config.getRuntime().shutdown(Duration.ofSeconds(1));
+      QContext.init(qInstance, session);
+      assertThat(completed(run).getErrorCode()).isEqualTo("INTERRUPTED");
+   }
+
+
+
+   /*******************************************************************************
+    ** Tracker progress is phase-based; its Stop callback cancels the local run.
+    *******************************************************************************/
+   @Test
+   void trackerAndTrackerFailures() throws Exception
+   {
+      ControlledProvider controlled = controlled(false);
+      RecordingTracker tracker = new RecordingTracker();
+      config.setRunTracker(tracker);
+      RunningTurn run = api.startTurn(conversation(), Map.of("text", "wait"));
+      controlled.awaitCalls(1);
+      await(() -> tracker.cancel != null);
+      tracker.cancel.run();
+      assertThat(completed(run).getStatus()).isEqualTo("CANCELLED");
+      assertThat(tracker.starts.get()).isEqualTo(1);
+      assertThat(tracker.phases).containsExactly("thinking", "writing");
+      assertThat(tracker.finishes.get()).isEqualTo(1);
+      assertThat(tracker.label).isEqualTo("Assistant answer");
+      tracker.fail = true;
+      config.withModelProvider(provider);
+      config.getRuntime().getProviderService().invalidate();
+      provider.thenText("Still works");
+      RunningTurn throwing = api.startTurn(conversation(), Map.of("text", "hello"));
+      assertThat(completed(throwing).getStatus()).isEqualTo("COMPLETE");
+      assertThat(tracker.finishes.get()).isEqualTo(2);
+   }
+
+
+
+   /*******************************************************************************
+    ** Build a remote persisted turn with an assistant message to recover.
+    *******************************************************************************/
+   private AssistantTurn remote(Instant heartbeat) throws Exception
+   {
+      Integer conversation = conversation();
+      AssistantMessage message = store.insert(new AssistantMessage().withConversationId(conversation).withUserId(EDITOR)
+         .withRole("ASSISTANT").withStatus("STREAMING").withSeq(1).withPartsJson("[]"));
+      return (store.insert(new AssistantTurn().withConversationId(conversation).withUserId(EDITOR).withAssistantMessageId(message.getId())
+         .withStatus("RUNNING").withStartedAt(heartbeat).withHeartbeatAt(heartbeat).withLeaseOwner("dead-pod").withPhase("thinking")));
+   }
+
+
+
+   /*******************************************************************************
+    ** Create a user-owned conversation.
+    *******************************************************************************/
+   private Integer conversation() throws Exception
+   {
+      return ((Integer) api.createConversation(Map.of()).get("id"));
+   }
+
+
+
+   /*******************************************************************************
+    ** Read the active-run response.
+    *******************************************************************************/
+   @SuppressWarnings("unchecked")
+   private List<Map<String, Object>> active() throws Exception
+   {
+      return ((List<Map<String, Object>>) api.activeTurns().get("turns"));
+   }
+
+
+
+   /*******************************************************************************
+    ** Wait for both persisted completion and local cleanup, then check replay.
+    *******************************************************************************/
+   private AssistantTurn completed(RunningTurn run) throws Exception
+   {
+      await(() -> config.getRuntime().getRunningTurn(run.getTurnId()) == null);
+      assertThat(run.getLog().isClosed()).isTrue();
+      assertThat(run.getLog().after(0, 1)).filteredOn(TurnEvent::isTerminal).hasSize(1);
+      AssistantTurn row = store.getTurn(EDITOR, run.getTurnId());
+      assertThat(row.getStatus()).isNotIn("RUNNING", "CANCELLING");
+      assertThat(api.turnEvents(run.getTurnId(), 0).persisted()).last().extracting(TurnEvent::getType).isEqualTo(TurnEvent.MESSAGE_END);
+      return (row);
+   }
+
+
+
+   /*******************************************************************************
+    ** Install a deterministic provider before the first call resolves it.
+    *******************************************************************************/
+   private ControlledProvider controlled(boolean stubborn)
+   {
+      ControlledProvider result = new ControlledProvider(stubborn);
+      config.withModelProvider(result);
+      return (result);
+   }
+
+
+
+   /*******************************************************************************
+    ** Short polling with a hard bound, without timing-sensitive fixed waits.
+    *******************************************************************************/
+   private static void await(BooleanSupplier condition) throws InterruptedException
+   {
+      long until = System.nanoTime() + Duration.ofSeconds(6).toNanos();
+      while(!condition.getAsBoolean() && System.nanoTime() < until)
+      {
+         Thread.sleep(5);
+      }
+      assertThat(condition.getAsBoolean()).as("condition reached within six seconds").isTrue();
+   }
+
+
+
+   /*******************************************************************************
+    ** MemoryRecordStore iterates its synchronized maps without holding their
+    ** lock. Serialize individual backend calls, as in RobustnessTest, so the
+    ** fixture models atomic database operations while turns still overlap.
+    *******************************************************************************/
+   private static class AtomicCallsStore extends AssistantStore
+   {
+      private static final Object BACKEND_LOCK = new Object();
+
+      /*******************************************************************************
+       ** Preserve encryption and other configured persistence behavior.
+       *******************************************************************************/
+      AtomicCallsStore(AssistantQBitConfig config)
+      {
+         super(config);
+      }
+
+      /*******************************************************************************
+       ** Make a memory query atomic with respect to insert/update operations.
+       *******************************************************************************/
+      @Override
+      public <T extends QRecordEntity> List<T> query(String table, QQueryFilter filter, Class<T> type) throws QException
+      {
+         synchronized(BACKEND_LOCK)
+         {
+            return (super.query(table, filter, type));
+         }
+      }
+
+      /*******************************************************************************
+       ** Make an insert atomic with respect to memory queries.
+       *******************************************************************************/
+      @Override
+      public <T extends QRecordEntity> T insert(T entity) throws QException
+      {
+         synchronized(BACKEND_LOCK)
+         {
+            return (super.insert(entity));
+         }
+      }
+
+      /*******************************************************************************
+       ** Make an update atomic with respect to memory queries.
+       *******************************************************************************/
+      @Override
+      public void updateFields(String table, QRecord record) throws QException
+      {
+         synchronized(BACKEND_LOCK)
+         {
+            super.updateFields(table, record);
+         }
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** Streams partial text, then blocks until explicitly released.
+    *******************************************************************************/
+   private static class ControlledProvider extends ScriptedModelProvider
+   {
+      private final boolean stubborn;
+      private final List<ControlledHandle> handles = new CopyOnWriteArrayList<>();
+      private boolean emitText = true;
+
+      /*******************************************************************************
+       ** Configure whether cancel and interruption are deliberately ignored.
+       *******************************************************************************/
+      ControlledProvider(boolean stubborn)
+      {
+         this.stubborn = stubborn;
+      }
+
+      /*******************************************************************************
+       ** Start a controlled stream.
+       *******************************************************************************/
+      @Override
+      public StreamHandle stream(ModelRequest request, ModelEventListener listener)
+      {
+         ControlledHandle handle = new ControlledHandle(stubborn);
+         if(emitText)
+         {
+            listener.onTextDelta("A partial answer that has already begun streaming to the user. ");
+         }
+         handles.add(handle);
+         return (handle);
+      }
+
+      /*******************************************************************************
+       ** Await a known number of started calls.
+       *******************************************************************************/
+      void awaitCalls(int count) throws InterruptedException
+      {
+         await(() -> handles.size() >= count);
+      }
+
+      /*******************************************************************************
+       ** Always release test threads, including deliberately wedged ones.
+       *******************************************************************************/
+      void release()
+      {
+         handles.forEach(h -> h.release.countDown());
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** A model that can deliberately violate the provider timeout contract.
+    *******************************************************************************/
+   private static class ControlledHandle implements StreamHandle
+   {
+      private final boolean stubborn;
+      private final CountDownLatch release = new CountDownLatch(1);
+      private volatile boolean cancelled;
+      private volatile boolean returned;
+
+      /*******************************************************************************
+       ** Configure cancellation behavior.
+       *******************************************************************************/
+      ControlledHandle(boolean stubborn)
+      {
+         this.stubborn = stubborn;
+      }
+
+      /*******************************************************************************
+       ** Abort unless this is the wedged-provider test.
+       *******************************************************************************/
+      @Override
+      public void cancel()
+      {
+         cancelled = true;
+         if(!stubborn)
+         {
+            release.countDown();
+         }
+      }
+
+      /*******************************************************************************
+       ** Observe cancellation.
+       *******************************************************************************/
+      @Override
+      public boolean isCancelled()
+      {
+         return (cancelled);
+      }
+
+      /*******************************************************************************
+       ** Block deterministically; stubborn mode ignores timeouts and interrupts.
+       *******************************************************************************/
+      @Override
+      public ModelResponse await(Duration timeout) throws InterruptedException
+      {
+         while(release.getCount() != 0)
+         {
+            try
+            {
+               release.await();
+            }
+            catch(InterruptedException e)
+            {
+               if(!stubborn)
+               {
+                  throw (e);
+               }
+            }
+         }
+         returned = true;
+         return (new ModelResponse().withParts(List.of(ModelPart.text("Done")))
+            .withStopReason(cancelled ? ModelResponse.STOP_CANCELLED : ModelResponse.STOP_END_TURN));
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** Records the host job-tray contract and can throw from every callback.
+    *******************************************************************************/
+   private static class RecordingTracker implements AssistantRunTracker
+   {
+      private final AtomicInteger starts = new AtomicInteger();
+      private final AtomicInteger finishes = new AtomicInteger();
+      private final List<String> phases = new CopyOnWriteArrayList<>();
+      private volatile Runnable cancel;
+      private String label;
+      private boolean fail;
+
+      /*******************************************************************************
+       ** Record publication.
+       *******************************************************************************/
+      @Override
+      public String start(String userId, Integer turnId, Integer conversationId, String label)
+      {
+         starts.incrementAndGet();
+         this.label = label;
+         if(fail)
+         {
+            throw (new IllegalStateException("tracker start failed"));
+         }
+         return ("job-" + turnId);
+      }
+
+      /*******************************************************************************
+       ** Record a phase transition.
+       *******************************************************************************/
+      @Override
+      public void progress(String trackingId, String phase, String message)
+      {
+         phases.add(phase);
+         if(fail)
+         {
+            throw (new IllegalStateException("tracker progress failed"));
+         }
+      }
+
+      /*******************************************************************************
+       ** Record terminal notification exactly once.
+       *******************************************************************************/
+      @Override
+      public void finish(String trackingId, String status, String message)
+      {
+         finishes.incrementAndGet();
+         if(fail)
+         {
+            throw (new IllegalStateException("tracker finish failed"));
+         }
+      }
+
+      /*******************************************************************************
+       ** Retain the host's Stop callback.
+       *******************************************************************************/
+      @Override
+      public void onCancel(String trackingId, Runnable cancel)
+      {
+         this.cancel = cancel;
+      }
+   }
+}

qbit-assistant/src/test/java/com/kingsrook/qbits/assistant/engine/EngineComponentsTest.java

@@ -151,8 +151,7 @@ class EngineComponentsTest extends BaseAssistantTest
 
       RateLimiter limiter = new RateLimiter(clock);
       assertThat(limiter.tryAcquire("u", 2, 1)).isNull();
-      assertThat(limiter.tryAcquire("u", 2, 1)).contains("in progress");
-      limiter.release("u");
+
       assertThat(limiter.tryAcquire("u", 2, 1)).isNull();
       limiter.release("u");
       assertThat(limiter.tryAcquire("u", 2, 1)).contains("last minute");

qbit-assistant/src/test/java/com/kingsrook/qbits/assistant/engine/RobustnessTest.java

@@ -119,7 +119,7 @@ class RobustnessTest extends BaseAssistantTest
          // idempotent: a second look adds nothing             //
          ////////////////////////////////////////////////////////
          assertThat(api.turnEvents(turn.getId(), 0).persisted()).hasSize(4);
-         assertThatThrownBy(() -> api.cancelTurn(turn.getId())).isInstanceOfSatisfying(AssistantApiException.class, e -> assertThat(e.getStatus()).isEqualTo(409));
+         assertThat(api.cancelTurn(turn.getId())).containsEntry("status", "ERROR");
 
          assertThat(api.turnEvents(young.getId(), 0).finished()).isFalse();
          assertThatThrownBy(() -> api.deleteConversation(conversation.getId())).isInstanceOfSatisfying(AssistantApiException.class, e -> assertThat(e.getStatus()).isEqualTo(409));

qbit-assistant/src/test/java/com/kingsrook/qbits/assistant/persistence/SchemaForeignKeyPostgresTest.java

@@ -0,0 +1,387 @@
+/*
+ * Copyright 2026 Kingsrook, LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.kingsrook.qbits.assistant.persistence;
+
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.ResultSet;
+import java.sql.Statement;
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import com.kingsrook.qbits.assistant.testing.BaseAssistantTest;
+import com.kingsrook.qqq.backend.core.model.metadata.fields.QFieldMetaData;
+import com.kingsrook.qqq.backend.core.model.metadata.joins.JoinOn;
+import com.kingsrook.qqq.backend.core.model.metadata.joins.QJoinMetaData;
+import com.kingsrook.qqq.backend.core.model.metadata.possiblevalues.QPossibleValueSource;
+import com.kingsrook.qqq.backend.core.model.metadata.possiblevalues.QPossibleValueSourceType;
+import com.kingsrook.qqq.backend.core.model.metadata.tables.QTableMetaData;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.testcontainers.containers.PostgreSQLContainer;
+import org.testcontainers.junit.jupiter.Container;
+import org.testcontainers.junit.jupiter.Testcontainers;
+import org.testcontainers.utility.DockerImageName;
+import static org.assertj.core.api.Assertions.assertThat;
+
+
+/*******************************************************************************
+ ** Guardrail for the reference DDL (docs/schema-postgres.sql) on a real
+ ** PostgreSQL: every relation the qbit declares (a table possible-value source
+ ** on an assistant_ field, or a join between assistant_ tables), plus the
+ ** relations only the code knows, has a foreign key with the intended ON DELETE
+ ** rule, and every foreign key column leads an index. A new relation without a
+ ** foreign key fails here unless it is added to EXEMPT with a reason.
+ *******************************************************************************/
+@Testcontainers(disabledWithoutDocker = true)
+class SchemaForeignKeyPostgresTest extends BaseAssistantTest
+{
+   @Container
+   static final PostgreSQLContainer<?> POSTGRES = new PostgreSQLContainer<>(DockerImageName.parse("pgvector/pgvector:pg16").asCompatibleSubstituteFor("postgres"));
+
+   /////////////////////////////////////////////////////////////////////////
+   // relations the meta-data does not declare (no possible-value source) //
+   /////////////////////////////////////////////////////////////////////////
+   private static final List<Relation> CODE_ONLY = List.of(
+      new Relation("assistant_data_audit", "turn_id", "assistant_turn"),
+      new Relation("assistant_data_audit", "provider_id", "assistant_provider"),
+      new Relation("assistant_budget_usage", "provider_id", "assistant_provider"));
+
+   //////////////////////////////////////////////////////////////////
+   // relations that deliberately have no foreign key, with reason //
+   //////////////////////////////////////////////////////////////////
+   private static final Map<Relation, String> EXEMPT = Map.of(
+      new Relation("assistant_budget_usage", "usage_id", "assistant_usage"),
+      "budget accounting projection: it must outlive its usage row so budgets keep counting the spend");
+
+   ///////////////////////////////////////////////////////////////////////////
+   // the intended ON DELETE rule (pg confdeltype: a NO ACTION, c CASCADE,  //
+   // n SET NULL) - see the foreign key block in docs/schema-postgres.sql   //
+   ///////////////////////////////////////////////////////////////////////////
+   private static final Map<Relation, String> RULES = new LinkedHashMap<>();
+
+   static
+   {
+      rule("assistant_message", "conversation_id", "assistant_conversation", "c");
+      rule("assistant_message", "parent_message_id", "assistant_message", "n");
+      rule("assistant_message", "turn_id", "assistant_turn", "n");
+      rule("assistant_turn", "conversation_id", "assistant_conversation", "c");
+      rule("assistant_turn", "user_message_id", "assistant_message", "n");
+      rule("assistant_turn", "assistant_message_id", "assistant_message", "n");
+      rule("assistant_turn_event", "turn_id", "assistant_turn", "c");
+      rule("assistant_tool_call", "conversation_id", "assistant_conversation", "c");
+      rule("assistant_tool_call", "turn_id", "assistant_turn", "c");
+      rule("assistant_tool_call", "pending_action_id", "assistant_pending_action", "n");
+      rule("assistant_feedback", "conversation_id", "assistant_conversation", "c");
+      rule("assistant_feedback", "message_id", "assistant_message", "c");
+      rule("assistant_pending_action", "conversation_id", "assistant_conversation", "c");
+      rule("assistant_pending_action", "turn_id", "assistant_turn", "n");
+      rule("assistant_data_audit", "conversation_id", "assistant_conversation", "n");
+      rule("assistant_data_audit", "turn_id", "assistant_turn", "n");
+      rule("assistant_data_audit", "provider_id", "assistant_provider", "a");
+      rule("assistant_usage", "conversation_id", "assistant_conversation", "n");
+      rule("assistant_usage", "turn_id", "assistant_turn", "n");
+      rule("assistant_usage", "provider_id", "assistant_provider", "a");
+      rule("assistant_budget_usage", "provider_id", "assistant_provider", "a");
+      rule("assistant_profile_skill", "profile_id", "assistant_profile", "c");
+      rule("assistant_profile_skill", "skill_id", "assistant_skill", "c");
+      rule("assistant_model", "provider_id", "assistant_provider", "c");
+      rule("assistant_scheduled_run", "conversation_id", "assistant_conversation", "n");
+      rule("assistant_scheduled_run", "turn_id", "assistant_turn", "n");
+   }
+
+
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   record Relation(String child, String column, String parent)
+   {
+      @Override
+      public String toString()
+      {
+         return (child + "." + column + " -> " + parent);
+      }
+   }
+
+
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   private static void rule(String child, String column, String parent, String rule)
+   {
+      RULES.put(new Relation(child, column, parent), rule);
+   }
+
+
+
+   /*******************************************************************************
+    ** Apply the whole reference DDL, then its foreign key block a second time
+    ** (it must be re-runnable on an existing database).
+    *******************************************************************************/
+   @BeforeAll
+   static void applyDdl() throws Exception
+   {
+      String ddl = Files.readString(Path.of("..", "docs", "schema-postgres.sql"));
+      try(Connection connection = connect(); Statement statement = connection.createStatement())
+      {
+         statement.execute(ddl);
+         int start = ddl.indexOf("-- Foreign keys (2026-10-14)");
+         if(start >= 0)
+         {
+            statement.execute(ddl.substring(start));
+         }
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** Every declared or code-only relation has a foreign key, unless exempt.
+    *******************************************************************************/
+   @Test
+   void everyRelationHasAForeignKey() throws Exception
+   {
+      Set<Relation> relations = new LinkedHashSet<>(declaredRelations());
+      assertThat(relations).as("declared relations found in the meta-data").hasSizeGreaterThan(20);
+      relations.addAll(CODE_ONLY);
+
+      Map<Relation, String> foreignKeys = foreignKeys();
+      List<String>          missing     = new ArrayList<>();
+      for(Relation relation : relations)
+      {
+         if(!foreignKeys.containsKey(relation) && !EXEMPT.containsKey(relation))
+         {
+            missing.add(relation.toString());
+         }
+      }
+      assertThat(missing).as("relations without a foreign key (add one to docs/schema-postgres.sql, or to EXEMPT with a reason)").isEmpty();
+
+      for(Relation exempt : EXEMPT.keySet())
+      {
+         assertThat(foreignKeys).as("exempt relation " + exempt + " must stay without a foreign key").doesNotContainKey(exempt);
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** The ON DELETE rules match how the qbit deletes.
+    *******************************************************************************/
+   @Test
+   void deleteRulesMatchTheDeletePaths() throws Exception
+   {
+      Map<Relation, String> foreignKeys = foreignKeys();
+      for(Map.Entry<Relation, String> entry : RULES.entrySet())
+      {
+         assertThat(foreignKeys.get(entry.getKey())).as(entry.getKey().toString()).isEqualTo(entry.getValue());
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** Every foreign key column is the first column of some index.
+    *******************************************************************************/
+   @Test
+   void everyForeignKeyColumnLeadsAnIndex() throws Exception
+   {
+      List<String> unindexed = new ArrayList<>();
+      try(Connection connection = connect(); Statement statement = connection.createStatement();
+         ResultSet rs = statement.executeQuery("""
+            SELECT c.conrelid::regclass::text, a.attname
+            FROM pg_constraint c
+            JOIN pg_attribute a ON a.attrelid = c.conrelid AND a.attnum = c.conkey[1]
+            WHERE c.contype = 'f' AND c.connamespace = 'public'::regnamespace
+              AND NOT EXISTS (SELECT 1 FROM pg_index i WHERE i.indrelid = c.conrelid AND i.indkey[0] = c.conkey[1])
+            """))
+      {
+         while(rs.next())
+         {
+            unindexed.add(rs.getString(1) + "." + rs.getString(2));
+         }
+      }
+      assertThat(unindexed).isEmpty();
+   }
+
+
+
+   /*******************************************************************************
+    ** AssistantStore.deleteConversation's delete order works under the foreign
+    ** keys; usage (cost accounting) survives with its pointers nulled. A plain
+    ** delete of a conversation (admin screen) cascades through the
+    ** message <-> turn cycle and keeps usage and the data audit.
+    *******************************************************************************/
+   @Test
+   void conversationDeletesWorkUnderTheForeignKeys() throws Exception
+   {
+      try(Connection connection = connect(); Statement statement = connection.createStatement())
+      {
+         connection.setAutoCommit(false);
+         for(int c : new int[] { 1, 2 })
+         {
+            int m = c * 10;
+            statement.execute("INSERT INTO assistant_provider (id, name, provider_type) VALUES (" + c + ", 'p" + c + "', 'anthropic')");
+            statement.execute("INSERT INTO assistant_conversation (id, user_id) VALUES (" + c + ", 'u')");
+            statement.execute("INSERT INTO assistant_message (id, conversation_id, user_id, role) VALUES (" + m + ", " + c + ", 'u', 'USER')");
+            statement.execute("INSERT INTO assistant_turn (id, conversation_id, user_id, user_message_id, provider_id) VALUES (" + c + ", " + c + ", 'u', " + m + ", NULL)");
+            statement.execute("INSERT INTO assistant_message (id, conversation_id, user_id, role, turn_id, parent_message_id) VALUES (" + (m + 1) + ", " + c + ", 'u', 'ASSISTANT', " + c + ", " + m + ")");
+            statement.execute("UPDATE assistant_message SET turn_id = " + c + " WHERE id = " + m);
+            statement.execute("UPDATE assistant_turn SET assistant_message_id = " + (m + 1) + " WHERE id = " + c);
+            statement.execute("INSERT INTO assistant_turn_event (turn_id, user_id) VALUES (" + c + ", 'u')");
+            statement.execute("INSERT INTO assistant_pending_action (id, conversation_id, turn_id, user_id) VALUES (" + c + ", " + c + ", " + c + ", 'u')");
+            statement.execute("INSERT INTO assistant_tool_call (conversation_id, turn_id, pending_action_id, user_id) VALUES (" + c + ", " + c + ", " + c + ", 'u')");
+            statement.execute("INSERT INTO assistant_feedback (conversation_id, message_id, user_id) VALUES (" + c + ", " + (m + 1) + ", 'u')");
+            statement.execute("INSERT INTO assistant_data_audit (id, conversation_id, turn_id, provider_id, user_id) VALUES (" + c + ", " + c + ", " + c + ", " + c + ", 'u')");
+            statement.execute("INSERT INTO assistant_usage (id, conversation_id, turn_id, provider_id, user_id) VALUES (" + c + ", " + c + ", " + c + ", " + c + ", 'u')");
+         }
+
+         ////////////////////////////////////////////////////////////
+         // conversation 1: AssistantStore.deleteConversation order //
+         ////////////////////////////////////////////////////////////
+         statement.execute("DELETE FROM assistant_turn_event WHERE turn_id IN (SELECT id FROM assistant_turn WHERE conversation_id = 1)");
+         for(String table : List.of("assistant_tool_call", "assistant_feedback", "assistant_message", "assistant_turn", "assistant_data_audit", "assistant_pending_action"))
+         {
+            statement.execute("DELETE FROM " + table + " WHERE conversation_id = 1");
+         }
+         statement.execute("DELETE FROM assistant_conversation WHERE id = 1");
+         assertThat(queryString(statement, "SELECT conversation_id || '/' || turn_id FROM assistant_usage WHERE id = 1")).as("usage kept, pointers nulled").isNull();
+         assertThat(queryString(statement, "SELECT provider_id::text FROM assistant_usage WHERE id = 1")).isEqualTo("1");
+
+         //////////////////////////////////////////////
+         // conversation 2: a plain conversation delete //
+         //////////////////////////////////////////////
+         statement.execute("DELETE FROM assistant_conversation WHERE id = 2");
+         for(String table : List.of("assistant_message", "assistant_turn", "assistant_tool_call", "assistant_feedback", "assistant_pending_action"))
+         {
+            assertThat(queryString(statement, "SELECT COUNT(*)::text FROM " + table + " WHERE conversation_id = 2")).as(table).isEqualTo("0");
+         }
+         assertThat(queryString(statement, "SELECT COUNT(*)::text FROM assistant_turn_event")).isEqualTo("0");
+         assertThat(queryString(statement, "SELECT (conversation_id IS NULL AND turn_id IS NULL)::text FROM assistant_data_audit WHERE id = 2")).as("data audit kept").isEqualTo("true");
+         assertThat(queryString(statement, "SELECT (conversation_id IS NULL AND turn_id IS NULL)::text FROM assistant_usage WHERE id = 2")).as("usage kept").isEqualTo("true");
+         connection.rollback();
+      }
+   }
+
+
+
+   /*******************************************************************************
+    ** Possible-value-source fields and joins between assistant_ tables.
+    *******************************************************************************/
+   private List<Relation> declaredRelations()
+   {
+      List<Relation> relations = new ArrayList<>();
+      for(QTableMetaData table : qInstance.getTables().values())
+      {
+         if(!table.getName().startsWith("assistant_"))
+         {
+            continue;
+         }
+         for(QFieldMetaData field : table.getFields().values())
+         {
+            QPossibleValueSource pvs = field.getPossibleValueSourceName() == null ? null : qInstance.getPossibleValueSource(field.getPossibleValueSourceName());
+            if(pvs != null && pvs.getType() == QPossibleValueSourceType.TABLE && pvs.getTableName().startsWith("assistant_"))
+            {
+               relations.add(new Relation(table.getName(), snake(field.getName()), pvs.getTableName()));
+            }
+         }
+      }
+      for(QJoinMetaData join : qInstance.getJoins().values())
+      {
+         if(!join.getLeftTable().startsWith("assistant_") || !join.getRightTable().startsWith("assistant_"))
+         {
+            continue;
+         }
+         for(JoinOn on : join.getJoinOns())
+         {
+            if("id".equals(on.getLeftField()))
+            {
+               relations.add(new Relation(join.getRightTable(), snake(on.getRightField()), join.getLeftTable()));
+            }
+            else if("id".equals(on.getRightField()))
+            {
+               relations.add(new Relation(join.getLeftTable(), snake(on.getLeftField()), join.getRightTable()));
+            }
+         }
+      }
+      return (relations);
+   }
+
+
+
+   /*******************************************************************************
+    ** Single-column foreign keys in the database, with their delete rule.
+    *******************************************************************************/
+   private static Map<Relation, String> foreignKeys() throws Exception
+   {
+      Map<Relation, String> foreignKeys = new LinkedHashMap<>();
+      try(Connection connection = connect(); Statement statement = connection.createStatement();
+         ResultSet rs = statement.executeQuery("""
+            SELECT c.conrelid::regclass::text, a.attname, c.confrelid::regclass::text, c.confdeltype
+            FROM pg_constraint c
+            JOIN pg_attribute a ON a.attrelid = c.conrelid AND a.attnum = c.conkey[1]
+            WHERE c.contype = 'f' AND array_length(c.conkey, 1) = 1 AND c.connamespace = 'public'::regnamespace
+            """))
+      {
+         while(rs.next())
+         {
+            foreignKeys.put(new Relation(rs.getString(1), rs.getString(2), rs.getString(3)), rs.getString(4));
+         }
+      }
+      return (foreignKeys);
+   }
+
+
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   private static String queryString(Statement statement, String sql) throws Exception
+   {
+      try(ResultSet rs = statement.executeQuery(sql))
+      {
+         return (rs.next() ? rs.getString(1) : null);
+      }
+   }
+
+
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   private static String snake(String camel)
+   {
+      return (camel.replaceAll("([A-Z])", "_$1").toLowerCase());
+   }
+
+
+
+   /*******************************************************************************
+    **
+    *******************************************************************************/
+   private static Connection connect() throws Exception
+   {
+      return (DriverManager.getConnection(POSTGRES.getJdbcUrl(), POSTGRES.getUsername(), POSTGRES.getPassword()));
+   }
+}

qbit-assistant/src/test/java/com/kingsrook/qbits/assistant/testing/AssistantTestFixture.java

@@ -99,6 +99,7 @@ public class AssistantTestFixture
     *******************************************************************************/
    public static QInstance build(AssistantQBitConfig config) throws Exception
    {
+      config.setRegisterShutdownHook(false);
       MemoryRecordStore.fullReset();
       QContext.clear();