fix: session lifecycle guards to prevent runaway API spend (#1590) (#1693)

* fix: add session lifecycle guards to prevent runaway API spend (#1590)

Three root causes allowed 30+ subprocess accumulation over 36 hours:
1. SIGTERM-killed processes (code 143) triggered crash recovery and
   immediately respawned — now detected and treated as intentional
   termination (aborts controller so wasAborted=true in .finally).
2. No wall-clock limit: sessions ran for 13+ hours continuously
   spending tokens — now refuses new generators after 4 hours and
   drains the pending queue to prevent further spawning.
3. Duplicate --resume processes for the same session UUID — now
   killed and unregistered before a new spawn is registered.

Generated by Claude Code
Vibe coded by ousamabenyounes

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

* fix: use normalized errorMsg in logger.error payload and annotate SIGTERM override

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* fix: use persisted createdAt for wall-clock guard and bind abortController locally to prevent stale abort

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* chore: re-trigger CodeRabbit review after rate limit reset

* fix: defer process unregistration until exit and align boundary test with strict > (#1693)

- ProcessRegistry: don't unregister PID immediately after SIGTERM — let the
  existing 'exit' handler clean up when the process actually exits, preventing
  tracking loss for still-live processes.
- Test: align wall-clock boundary test with production's strict `>` operator
  (exactly 4h is NOT terminated, only >4h is).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude <noreply@anthropic.com>

src/services/worker/ProcessRegistry.ts

@@ -382,6 +382,30 @@ export function createPidCapturingSpawn(sessionDbId: number) {
     env?: NodeJS.ProcessEnv;
     signal?: AbortSignal;
   }) => {
+    // Kill any existing process for this session before spawning a new one.
+    // Multiple processes sharing the same --resume UUID waste API credits and
+    // can conflict with each other (Issue #1590).
+    const existing = getProcessBySession(sessionDbId);
+    if (existing && existing.process.exitCode === null) {
+      logger.warn('PROCESS', `Killing duplicate process PID ${existing.pid} before spawning new one for session ${sessionDbId}`, {
+        existingPid: existing.pid,
+        sessionDbId
+      });
+      let exited = false;
+      try {
+        existing.process.kill('SIGTERM');
+        exited = existing.process.exitCode !== null;
+      } catch {
+        // Already dead — safe to unregister immediately
+        exited = true;
+      }
+
+      if (exited) {
+        unregisterProcess(existing.pid);
+      }
+      // If still alive, the 'exit' handler (line ~440) will unregister it.
+    }
+
     getSupervisor().assertCanSpawn('claude sdk');
 
     // On Windows, use cmd.exe wrapper for .cmd files to properly handle paths with spaces