Cancel stale retries when issue ownership changes (#4445)

## Thinking Path

> - Paperclip orchestrates AI agents for zero-human companies
> - Issue execution is guarded by run locks and bounded retry scheduling
> - A failed run can schedule a retry, but the issue may be reassigned
before that retry becomes due
> - The old assignee's scheduled retry should not continue to hold or
reclaim execution for the issue
> - This pull request cancels stale scheduled retries when ownership
changes and cancels live work when an issue is explicitly cancelled
> - The benefit is cleaner issue handoff semantics and fewer stranded or
incorrect execution locks

## What Changed

- Cancel scheduled retry runs when their issue has been reassigned
before the retry is promoted.
- Clear stale issue execution locks and cancel the associated wakeup
request when a stale retry is cancelled.
- Avoid deferring a new assignee behind a previous assignee's scheduled
retry.
- Cancel an active run when an issue status is explicitly changed to
`cancelled`, while leaving `done` transitions alone.
- Added route and heartbeat regressions for reassignment and
cancellation behavior.

## Verification

- `pnpm exec vitest run --project @paperclipai/server
server/src/__tests__/heartbeat-retry-scheduling.test.ts
server/src/__tests__/issue-comment-reopen-routes.test.ts --pool=forks
--poolOptions.forks.isolate=true`
  - `issue-comment-reopen-routes.test.ts`: 28 passed.
- `heartbeat-retry-scheduling.test.ts`: skipped by the existing embedded
Postgres host guard (`Postgres init script exited with code null`).
- `pnpm --filter @paperclipai/server typecheck`

## Risks

- Medium risk because this changes heartbeat retry lifecycle behavior.
- The cancellation path is scoped to scheduled retries whose issue
assignee no longer matches the retrying agent, and logs a lifecycle
event for auditability.
- No migrations.

> For core feature work, check [`ROADMAP.md`](ROADMAP.md) first and
discuss it in `#dev` before opening the PR. Feature PRs that overlap
with planned core work may need to be redirected — check the roadmap
first. See `CONTRIBUTING.md`.

## Model Used

- OpenAI Codex, GPT-5 coding agent, tool-enabled with
shell/GitHub/Paperclip API access. Context window was not reported by
the runtime.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] If this change affects the UI, I have included before/after
screenshots
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] I will address all Greptile and reviewer comments before
requesting merge

---------

Co-authored-by: Paperclip <noreply@paperclip.ing>

server/src/routes/issues.ts

@@ -1910,6 +1910,8 @@ export function issueRoutes(
       hiddenAt: hiddenAtRaw,
       ...updateFields
     } = req.body;
+    const shouldCancelActiveRunForCancelledStatus =
+      existing.status !== "cancelled" && updateFields.status === "cancelled";
     if (resumeRequested === true && !commentBody) {
       res.status(400).json({ error: "Follow-up intent requires a comment" });
       return;
@@ -1982,6 +1984,10 @@ export function issueRoutes(
       }
     }
 
+    const runToCancelForCancelledStatus = shouldCancelActiveRunForCancelledStatus
+      ? await resolveActiveIssueRun(existing)
+      : null;
+
     if (hiddenAtRaw !== undefined) {
       updateFields.hiddenAt = hiddenAtRaw ? new Date(hiddenAtRaw) : null;
     }
@@ -2134,6 +2140,41 @@ export function issueRoutes(
       res.status(404).json({ error: "Issue not found" });
       return;
     }
+
+    let cancelledStatusRunId: string | null = null;
+    if (runToCancelForCancelledStatus) {
+      try {
+        const cancelled = await heartbeat.cancelRun(runToCancelForCancelledStatus.id);
+        if (cancelled) {
+          cancelledStatusRunId = cancelled.id;
+          await logActivity(db, {
+            companyId: cancelled.companyId,
+            actorType: actor.actorType,
+            actorId: actor.actorId,
+            agentId: actor.agentId,
+            runId: actor.runId,
+            action: "heartbeat.cancelled",
+            entityType: "heartbeat_run",
+            entityId: cancelled.id,
+            details: { agentId: cancelled.agentId, source: "issue_status_cancelled", issueId: existing.id },
+          });
+        }
+      } catch (err) {
+        logger.warn({ err, issueId: existing.id, runId: runToCancelForCancelledStatus.id }, "failed to cancel run for cancelled issue");
+        await logActivity(db, {
+          companyId: existing.companyId,
+          actorType: actor.actorType,
+          actorId: actor.actorId,
+          agentId: actor.agentId,
+          runId: actor.runId,
+          action: "heartbeat.cancel_failed",
+          entityType: "heartbeat_run",
+          entityId: runToCancelForCancelledStatus.id,
+          details: { source: "issue_status_cancelled", issueId: existing.id },
+        });
+      }
+    }
+
     if (titleOrDescriptionChanged) {
       await issueReferencesSvc.syncIssue(issue.id);
     }
@@ -2200,6 +2241,7 @@ export function issueRoutes(
         ...(resumeRequested === true ? { resumeIntent: true, followUpRequested: true } : {}),
         ...(reopened ? { reopened: true, reopenedFrom: reopenFromStatus } : {}),
         ...(interruptedRunId ? { interruptedRunId } : {}),
+        ...(cancelledStatusRunId ? { cancelledStatusRunId } : {}),
         _previous: hasFieldChanges ? previous : undefined,
         ...summarizeIssueReferenceActivityDetails(
           updateReferenceDiff