diff --git a/build/Test-InstalledUpdates.ps1 b/build/Test-InstalledUpdates.ps1
index edf4e28..a1b2404 100644
--- a/build/Test-InstalledUpdates.ps1
+++ b/build/Test-InstalledUpdates.ps1
@@ -77,15 +77,17 @@ function Invoke-SmokeProcess
    $stderr = $process.StandardError.ReadToEndAsync()
    try
    {
-      if(-not $process.WaitForExit($TimeoutSeconds * 1000))
+      $timedOut = -not $process.WaitForExit($TimeoutSeconds * 1000)
+      if($timedOut)
       {
          $process.Kill($true)
-         throw "Process timed out: $File"
+         if(-not $process.WaitForExit(10000)) { throw "Timed-out process did not terminate: $File" }
       }
       $script:smokeProcessNumber++
       $log = Join-Path $outputRoot "process-$script:smokeProcessNumber.log"
       $text = $stdout.GetAwaiter().GetResult() + $stderr.GetAwaiter().GetResult()
       Set-Content -LiteralPath $log -Value $text
+      if($timedOut) { throw "Process timed out: $File. Log: $log" }
       if($process.ExitCode -ne 0) { throw "Process failed ($($process.ExitCode)): $File. Log: $log`n$text" }
    }
    finally { $process.Dispose() }
@@ -183,7 +185,7 @@ try
    if($loose.Installed -or $loose.AppKitSupported -or $null -ne $loose.Version) { throw 'Loose publish output unexpectedly supports updates.' }
    $records.Add(@{ kind = 'loose'; result = $loose })
    $env:K22_UITEST_EXE = Join-Path $buildRoot "publish/0.1.0/$mainExe"
-   Invoke-SmokeProcess -File 'dotnet' -Arguments @('test', "$repositoryRoot/tests/$name.UiTests", '--no-build', '--logger', 'trx;LogFileName=published-ui.trx', '--results-directory', $outputRoot) -TimeoutSeconds 180
+   Invoke-SmokeProcess -File 'dotnet' -Arguments @('test', "$repositoryRoot/tests/$name.UiTests", '--no-build', '--logger', 'trx;LogFileName=published-ui.trx', '--results-directory', $outputRoot) -TimeoutSeconds 300
    foreach($initial in @($versions[0], $versions[2]))
    {
       $portableDirectory = Join-Path $outputRoot "portable-$($initial.channel)"
@@ -234,7 +236,7 @@ try
          $after = Get-SmokeResult -Exe $installedProbe -ResultPath (Join-Path $outputRoot "$channel-after.json")
          if($after.Version -ne $initial.target -or $after.Channel -ne $channel -or $null -ne $after.UpdateVersion -or $after.AppKitVersion -ne $initial.target) { throw 'Post-upgrade identity or channel is incorrect.' }
          $env:K22_UITEST_EXE = $currentExe
-         Invoke-SmokeProcess -File 'dotnet' -Arguments @('test', "$repositoryRoot/tests/$name.UiTests", '--no-build', '--filter', 'FullyQualifiedName!~CheckForUpdates_InALooseBuild', '--logger', "trx;LogFileName=installed-$channel-ui.trx", '--results-directory', $outputRoot) -TimeoutSeconds 180
+         Invoke-SmokeProcess -File 'dotnet' -Arguments @('test', "$repositoryRoot/tests/$name.UiTests", '--no-build', '--filter', 'FullyQualifiedName!~CheckForUpdates_InALooseBuild', '--logger', "trx;LogFileName=installed-$channel-ui.trx", '--results-directory', $outputRoot) -TimeoutSeconds 300
          $records.Add(@{ kind = 'installed'; channel = $channel; before = $before; after = $after; restarted = $true; appSha256 = $installedHash })
       }
       finally
diff --git a/docs/SESSION-STATE.md b/docs/SESSION-STATE.md
index 41241ef..e36d248 100644
--- a/docs/SESSION-STATE.md
+++ b/docs/SESSION-STATE.md
@@ -11,6 +11,29 @@ Owner authorized signed/DCO commits, pushes, repository configuration and ticket
 No merges, tags/releases or new Azure attempts. Human review acknowledgement remains
 required. Local desktop reservation is unanswered; hosted runner UI tests are authorized.
 
+## Source caret alignment probe — 2026-10-11
+
+82898bd / CI 38117005710 isolated source job 114403773700 reproduced FAILURE
+in 18 seconds. Original timeout is now retained: source focus before=5310.933,
+last=5310.933; after physical pointer press, actual native offset resets to 0.
+The provider cannot retrieve the offscreen last-heading glyph. This rejects the
+hypothesis that GettingFocus captured an already-reset offset; deferred restoration
+ran too early to prevent later native caret work. Original full assertions stay intact.
+
+The single-variable probe positions a zero-length caret at the first visible native
+character before focus, using bounded binary search over real native character
+rectangles. Active find/nonempty selections remain independent. The previous snapshot-
+guarded viewport restoration remains. DEBUG-src-focus records the native caret index;
+remove probes/temporary CI job after actual original acceptance proves the fix.
+Full/native/installed producers on 82898bd remain observed until terminal before push.
+
+The enlarged 48-case suite's measured native failure duration is 178 seconds and
+published acceptance exceeded 180 seconds before producing TRX. Full published/
+installed UI suites receive a bounded 300 seconds (all cases/assertions unchanged).
+The process helper retains stdout/stderr after timed-out child termination before
+throwing; a 10-second termination bound still fails closed. Other command timeouts
+remain unchanged. A headless owned-child timeout probe checks retained evidence.
+
 ## Tight native source diagnostics after editor acceptance
 
 f650e36 / CI 38116258625 native job 114401630861 finished FAILURE:
diff --git a/src/MarkdownViewr.Windows/MainWindow.Source.Sync.cs b/src/MarkdownViewr.Windows/MainWindow.Source.Sync.cs
index 9bb851c..576440a 100644
--- a/src/MarkdownViewr.Windows/MainWindow.Source.Sync.cs
+++ b/src/MarkdownViewr.Windows/MainWindow.Source.Sync.cs
@@ -54,9 +54,27 @@ public sealed partial class MainWindow
          return;
       }
       double position = scroller.VerticalOffset;
+      if(SourceText.SelectionLength == 0 && SourceText.Text.Length > 0)
+      {
+         int first = 0;
+         int last = SourceText.Text.Length - 1;
+         while(first < last)
+         {
+            int middle = first + (last - first) / 2;
+            if(SourceText.GetRectFromCharacterIndex(middle, trailingEdge: false).Y < position)
+            {
+               first = middle + 1;
+            }
+            else
+            {
+               last = middle;
+            }
+         }
+         SourceText.Select(first, 0);
+      }
       if(string.Equals(Environment.GetEnvironmentVariable("MARKDOWNVIEWR_INPUT_TRACE"), "1", StringComparison.Ordinal))
       {
-         App.Log.Info(FormattableString.Invariant($"Input trace: source focus before={position:R}, last={_sourceLastY:R}."));
+         App.Log.Info(FormattableString.Invariant($"[DEBUG-src-focus] source focus before={position:R}, last={_sourceLastY:R}, caret={SourceText.SelectionStart}."));
       }
       Core.Documents.DocumentSourceText? snapshot = _sourceDocument;
       DispatcherQueue.TryEnqueue(() =>