fix(ci): pin Xcode 26.x, drop phantom VoiceLog, harden Batcher timing

CI run 25799596445 failed on 6 SPM packages + the App target. Root cause
was a toolchain skew between local dev (Swift 6.3.2 / Xcode 26) and CI
(Swift 6.0 / Xcode 16):

- mlx-audio-swift v0.1.2 ships swift-tools-version:6.2 which Swift 6.0
  cannot parse, breaking Voice + Harness + the App target with
  "Dependencies could not be resolved because 'mlx-audio-swift' contains
  incompatible tools version (6.2.0)".
- MCP swift-sdk 0.12.0 uses the new `withThrowingTaskGroup` overload
  (no `of:` parameter) that only exists in Swift 6.2+.
- AgentCore tests use `@MainActor` XCTestCase with `await super.setUp()`,
  a pattern Swift 6.0 rejects but Swift 6.1+ accepts.

The macos-15 runner already ships Xcode 26.3 / 26.2 / 26.1 / 26.0
alongside 16.x, so the fix is to switch the Xcode select. Fallback to
Xcode_26.app preserves robustness against patch-level shuffles.

Also:
- Drop `VoiceLog` from the SPM matrix. No `packages/VoiceLog` directory
  exists; the job failed with `chdir error: No such file or directory`.
  Voice-log work is parked under v1.1.
- Bump BatcherTests `waitForDrain` from 80ms to 250ms. The batcher
  window is 33ms; 80ms was tight enough that macos-15 dropped
  test_tokenDeltaConcat with sendCount=0 because the scheduled drain
  hadn't completed its actor + main-actor hop before the test resumed.
  250ms (~7.5× the window) survives CI jitter; verified locally — all
  five Batcher tests pass in 1.27s.

Refs: CI run 25799596445.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -122,6 +122,9 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
+        # VoiceLog removed: no `packages/VoiceLog` directory exists in the
+        # repo. The matrix entry was a phantom that failed with `chdir error:
+        # No such file or directory`. Voice-log work tracked under v1.1.
         package:
           - AgentCore
           - Bus
@@ -136,20 +139,25 @@ jobs:
           - Shell
           - Vision
           - Voice
-          - VoiceLog
     steps:
       - uses: actions/checkout@v4
+      # Project targets macOS 26 Tahoe + Swift 6.2/6.3. Xcode 16 (Swift 6.0)
+      # cannot parse `mlx-audio-swift` v0.1.2's `swift-tools-version:6.2`,
+      # lacks the `withThrowingTaskGroup` overload used by MCP `swift-sdk`
+      # 0.12.0, and rejects `@MainActor` XCTestCase `super.setUp()` patterns
+      # that Swift 6.1+ accepts. Pin to the newest Xcode 26.x on macos-15.
+      # See actions/runner-images macos-15 readme for installed Xcode list.
       - name: Select Xcode
-        run: sudo xcode-select -s /Applications/Xcode_16.app/Contents/Developer || sudo xcode-select -s /Applications/Xcode.app/Contents/Developer
+        run: sudo xcode-select -s /Applications/Xcode_26.3.app/Contents/Developer || sudo xcode-select -s /Applications/Xcode_26.app/Contents/Developer
       - name: Show Swift toolchain
         run: |
           swift --version
           xcodebuild -version
       # Download the production webview bundle so Bus + downstream packages
-      # (AgentCore / Harness / MCP / Voice / VoiceLog) can mount a real
-      # WKWebView with a working JS bridge. Without this, BusTests fail
-      # with `Error: bus not mounted` because index.html + the JS bundle
-      # are missing from App/Resources/webview/.
+      # (AgentCore / Harness / MCP / Voice) can mount a real WKWebView with
+      # a working JS bridge. Without this, BusTests fail with `Error: bus
+      # not mounted` because index.html + the JS bundle are missing from
+      # App/Resources/webview/.
       - name: Download webview resources
         uses: actions/download-artifact@v4
         with:
@@ -173,8 +181,10 @@ jobs:
     needs: [boundary-gates, webview]
     steps:
       - uses: actions/checkout@v4
+      # Same Xcode 26.x pin as swift-packages — Xcode 16 cannot resolve
+      # mlx-audio-swift's swift-tools-version:6.2 manifest.
       - name: Select Xcode
-        run: sudo xcode-select -s /Applications/Xcode_16.app/Contents/Developer || sudo xcode-select -s /Applications/Xcode.app/Contents/Developer
+        run: sudo xcode-select -s /Applications/Xcode_26.3.app/Contents/Developer || sudo xcode-select -s /Applications/Xcode_26.app/Contents/Developer
       - name: Install xcodegen
         run: brew install xcodegen
       # Reuse the webview build from the upstream job rather than rebuilding.

packages/Bus/Tests/BusTests/BatcherTests.swift

@@ -3,7 +3,13 @@ import XCTest
 
 /// Exercises `OutboundBatcher` behaviour against a recording fake sink. All
 /// timing assertions are designed to survive CI jitter — the batcher's nominal
-/// window is 33ms; tests wait ≥60ms (≈2x) before asserting.
+/// window is 33ms; tests wait 250ms (≈7.5x) before asserting. The earlier
+/// 80ms wait was tight enough that macOS-15 GitHub Actions runners (cold
+/// build + cold WKWebView mount sharing the box) intermittently dropped
+/// `test_tokenDeltaConcat` with sendCount=0 — the 33ms `Task.sleep` had not
+/// yet hopped back through the batcher actor + main actor by the time the
+/// test resumed. 250ms gives the scheduled drain ample time without making
+/// the suite noticeably slower (the four affected tests cost ~1s total).
 ///
 /// The fake is `@MainActor`-isolated because `BusOutbound` does not cross
 /// actor boundaries by default under Swift 6 strict concurrency, and the
@@ -21,13 +27,16 @@ final class BatcherTests: XCTestCase {
         }
     }
 
-    // A small drain-wait helper. The batcher window is 33ms; wait 80ms to let
-    // the scheduled drain fire and propagate the main-actor hop.
-    // `@MainActor` because each test is main-actor-isolated and Swift 6 strict
-    // concurrency disallows sending `self` across a nonisolated boundary.
+    // A small drain-wait helper. The batcher window is 33ms; wait 250ms to
+    // let the scheduled drain fire and propagate the main-actor hop. The
+    // earlier 80ms wait was flaky on macos-15 CI runners (cold builds racing
+    // a cold WKWebView mount on the same box) — see commit message + doc
+    // comment above. `@MainActor` because each test is main-actor-isolated
+    // and Swift 6 strict concurrency disallows sending `self` across a
+    // nonisolated boundary.
     @MainActor
     private func waitForDrain() async {
-        try? await Task.sleep(for: .milliseconds(80))
+        try? await Task.sleep(for: .milliseconds(250))
     }
 
     // MARK: - Tests