diff --git a/docs-ai/064-agent-completion-signals/004-s2-work-note.md b/docs-ai/064-agent-completion-signals/004-s2-work-note.md
index 720ae62f..de713c37 100644
--- a/docs-ai/064-agent-completion-signals/004-s2-work-note.md
+++ b/docs-ai/064-agent-completion-signals/004-s2-work-note.md
@@ -93,6 +93,11 @@ recorded in the existing 064 plan/action documents.
 - 2026-08-23 — Applied Skill Workshop proposal `prowl-cli-20260823-a59b46f453` after owner
   authorization. The managed workspace skill is live and scan-clean; direct synchronization
   into the repository copy remains prohibited by the current Workshop target model.
+- 2026-08-23 — GitHub Actions exposed a runner-dependent test fixture: synthetic PID `400`
+  happened to be live on the hosted runner, so the default process start-date lookup added an
+  unexpected ancestry generation. The resolver test now injects a nil start-date provider for
+  its fake PID graph. Focused tests passed 3/3, `make check` passed, and the full gate again
+  passed 2453 reported / 2455 verified tests with zero failures.
 
 ## Fresh Debug E2E
 
diff --git a/supacodeTests/CallerPaneResolverTests.swift b/supacodeTests/CallerPaneResolverTests.swift
index 93ef298f..fdc1be16 100644
--- a/supacodeTests/CallerPaneResolverTests.swift
+++ b/supacodeTests/CallerPaneResolverTests.swift
@@ -12,14 +12,16 @@ struct CallerPaneResolverTests {
       CallerPaneResolver.pane(
         forCallerProcess: 100,
         paneByShellPID: [100: pane],
-        parentProcessID: { parents[$0] }
+        parentProcessID: { parents[$0] },
+        processStartDate: { _ in nil }
       ) == pane
     )
     #expect(
       CallerPaneResolver.pane(
         forCallerProcess: 400,
         paneByShellPID: [100: pane],
-        parentProcessID: { parents[$0] }
+        parentProcessID: { parents[$0] },
+        processStartDate: { _ in nil }
       ) == pane
     )
   }
@@ -31,14 +33,16 @@ struct CallerPaneResolverTests {
       CallerPaneResolver.pane(
         forCallerProcess: 400,
         paneByShellPID: [100: focusedButUnrelated],
-        parentProcessID: { _ in nil }
+        parentProcessID: { _ in nil },
+        processStartDate: { _ in nil }
       ) == nil
     )
     #expect(
       CallerPaneResolver.pane(
         forCallerProcess: 400,
         paneByShellPID: [100: focusedButUnrelated],
-        parentProcessID: { $0 }
+        parentProcessID: { $0 },
+        processStartDate: { _ in nil }
       ) == nil
     )
   }
@@ -50,14 +54,16 @@ struct CallerPaneResolverTests {
       CallerPaneResolver.pane(
         forCallerProcess: 100,
         paneByShellPID: [67: pane],
-        parentProcessID: { $0 - 1 }
+        parentProcessID: { $0 - 1 },
+        processStartDate: { _ in nil }
       ) == nil
     )
     #expect(
       CallerPaneResolver.pane(
         forCallerProcess: 100,
         paneByShellPID: [69: pane],
-        parentProcessID: { $0 - 1 }
+        parentProcessID: { $0 - 1 },
+        processStartDate: { _ in nil }
       ) == pane
     )
   }