FN-8096: bound runtime process cleanup listeners

Keep Grok and OMP ACP cleanup listeners bounded when Vitest reloads plugin modules.

- Store active ACP process registries on the process singleton.
- Guard each plugin's exit cleanup hook against duplicate module evaluation.
- Add lifecycle regressions that reject listener leaks and preserve child cleanup.

Files changed:
 .../src/__tests__/process-lifecycle.test.ts        | 54 ++++++++++++++++++++++
 .../src/acp/process-manager.ts                     | 16 ++++++-
 plugins/fusion-plugin-grok-runtime/src/index.ts    | 17 +++++--
 .../src/__tests__/process-lifecycle.test.ts        | 54 ++++++++++++++++++++++
 .../src/acp/process-manager.ts                     | 16 ++++++-
 plugins/fusion-plugin-omp-runtime/src/index.ts     | 17 +++++--
 6 files changed, 166 insertions(+), 8 deletions(-)

Fusion-Task-Id: FN-8096

Fusion-Task-Lineage: c8a5daba-e13c-464b-b7e6-11c07d264864

Co-authored-by: Fusion (runfusion.ai) <noreply@runfusion.ai>

plugins/fusion-plugin-grok-runtime/src/__tests__/process-lifecycle.test.ts

@@ -0,0 +1,54 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+const EVENTS = ["exit", "beforeExit", "SIGTERM", "SIGINT"] as const;
+
+function listenerCounts(): Record<(typeof EVENTS)[number], number> {
+  return Object.fromEntries(EVENTS.map((event) => [event, process.listenerCount(event)])) as Record<
+    (typeof EVENTS)[number],
+    number
+  >;
+}
+
+describe("Grok plugin process lifecycle", () => {
+  afterEach(() => {
+    vi.resetModules();
+  });
+
+  it("keeps its process cleanup owner bounded across repeated module evaluation", async () => {
+    const baseline = listenerCounts();
+    const warnings: Error[] = [];
+    const onWarning = (warning: Error) => warnings.push(warning);
+    process.on("warning", onWarning);
+
+    try {
+      for (let iteration = 0; iteration < 15; iteration += 1) {
+        vi.resetModules();
+        await import("../index.js");
+      }
+      await new Promise<void>((resolve) => setImmediate(resolve));
+    } finally {
+      process.off("warning", onWarning);
+    }
+
+    const after = listenerCounts();
+    expect(after.exit - baseline.exit).toBeLessThanOrEqual(1);
+    expect(after.beforeExit - baseline.beforeExit).toBe(0);
+    expect(after.SIGTERM - baseline.SIGTERM).toBe(0);
+    expect(after.SIGINT - baseline.SIGINT).toBe(0);
+    expect(warnings.filter((warning) => warning.name === "MaxListenersExceededWarning")).toEqual([]);
+
+    const manager = await import("../acp/process-manager.js");
+    const child = {
+      killed: false,
+      exitCode: null,
+      kill: vi.fn(),
+      on: vi.fn(),
+    };
+    manager.registerProcess(child as never);
+    for (const cleanup of process.listeners("exit")) {
+      if (cleanup.name === "killAllProcesses") cleanup(0);
+    }
+    expect(child.kill).toHaveBeenCalledWith("SIGKILL");
+    expect(manager.activeProcessCount()).toBe(0);
+  });
+});

plugins/fusion-plugin-grok-runtime/src/acp/process-manager.ts

@@ -21,8 +21,22 @@ function debugLog(message: string): void {
   console.error(`[grok-acp] ${message}`);
 }
 
+/*
+FNXC:ProcessLifecycle 2026-07-16-07:00:
+Vitest resets the Grok plugin module graph while retaining the worker's `process`.
+Keep the ACP child registry on `process` so the one guarded exit listener also
+reaps children registered by later module evaluations; adding one listener per
+evaluation causes MaxListenersExceededWarning in the dashboard backfill lane.
+*/
+const ACTIVE_PROCESSES_KEY = Symbol.for("fusion.plugin.grok-runtime.activeProcesses");
+const processWithActiveProcesses = process as typeof process & {
+  [key: symbol]: Set<ChildProcess> | undefined;
+};
+
 /** Registry of active agent subprocesses for teardown. Self-cleans on exit. */
-const activeProcesses = new Set<ChildProcess>();
+const activeProcesses =
+  processWithActiveProcesses[ACTIVE_PROCESSES_KEY] ??
+  (processWithActiveProcesses[ACTIVE_PROCESSES_KEY] = new Set<ChildProcess>());
 
 /**
  * Register a subprocess in the agent process registry.

plugins/fusion-plugin-grok-runtime/src/index.ts

@@ -25,9 +25,20 @@ fusion-plugin-acp-runtime, so bundled Grok does not depend on the experimental
 ACP example plugin package.
 */
 
-// Reap Grok ACP agent subprocesses on hard process exit (registry SIGKILL is
-// authoritative). Scoped to ACP-tracked agent children only — never port 4040.
-process.on("exit", killAllProcesses);
+/*
+FNXC:ProcessLifecycle 2026-07-16-07:00:
+The dashboard backfill worker repeatedly evaluates this plugin through
+`vi.resetModules()` while retaining the process singleton. Install one exit
+listener per Grok lifecycle owner and use the process-shared registry in the
+ACP manager so it reaps children from every evaluation. Do not appease this
+with `setMaxListeners`; the listener must stay bounded.
+*/
+const PROCESS_EXIT_HOOK_KEY = Symbol.for("fusion.plugin.grok-runtime.exitCleanup");
+const processWithExitHook = process as typeof process & { [key: symbol]: boolean | undefined };
+if (!processWithExitHook[PROCESS_EXIT_HOOK_KEY]) {
+  process.on("exit", killAllProcesses);
+  processWithExitHook[PROCESS_EXIT_HOOK_KEY] = true;
+}
 
 const plugin: FusionPlugin = definePlugin({
   manifest: {

plugins/fusion-plugin-omp-runtime/src/__tests__/process-lifecycle.test.ts

@@ -0,0 +1,54 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+const EVENTS = ["exit", "beforeExit", "SIGTERM", "SIGINT"] as const;
+
+function listenerCounts(): Record<(typeof EVENTS)[number], number> {
+  return Object.fromEntries(EVENTS.map((event) => [event, process.listenerCount(event)])) as Record<
+    (typeof EVENTS)[number],
+    number
+  >;
+}
+
+describe("OMP plugin process lifecycle", () => {
+  afterEach(() => {
+    vi.resetModules();
+  });
+
+  it("keeps its process cleanup owner bounded across repeated module evaluation", async () => {
+    const baseline = listenerCounts();
+    const warnings: Error[] = [];
+    const onWarning = (warning: Error) => warnings.push(warning);
+    process.on("warning", onWarning);
+
+    try {
+      for (let iteration = 0; iteration < 15; iteration += 1) {
+        vi.resetModules();
+        await import("../index.js");
+      }
+      await new Promise<void>((resolve) => setImmediate(resolve));
+    } finally {
+      process.off("warning", onWarning);
+    }
+
+    const after = listenerCounts();
+    expect(after.exit - baseline.exit).toBeLessThanOrEqual(1);
+    expect(after.beforeExit - baseline.beforeExit).toBe(0);
+    expect(after.SIGTERM - baseline.SIGTERM).toBe(0);
+    expect(after.SIGINT - baseline.SIGINT).toBe(0);
+    expect(warnings.filter((warning) => warning.name === "MaxListenersExceededWarning")).toEqual([]);
+
+    const manager = await import("../acp/process-manager.js");
+    const child = {
+      killed: false,
+      exitCode: null,
+      kill: vi.fn(),
+      on: vi.fn(),
+    };
+    manager.registerProcess(child as never);
+    for (const cleanup of process.listeners("exit")) {
+      if (cleanup.name === "killAllProcesses") cleanup(0);
+    }
+    expect(child.kill).toHaveBeenCalledWith("SIGKILL");
+    expect(manager.activeProcessCount()).toBe(0);
+  });
+});

plugins/fusion-plugin-omp-runtime/src/acp/process-manager.ts

@@ -21,8 +21,22 @@ function debugLog(message: string): void {
   console.error(`[grok-acp] ${message}`);
 }
 
+/*
+FNXC:ProcessLifecycle 2026-07-16-07:00:
+Vitest resets the OMP plugin module graph while retaining the worker's `process`.
+Keep the ACP child registry on `process` so the one guarded exit listener also
+reaps children registered by later module evaluations; adding one listener per
+evaluation causes MaxListenersExceededWarning in the dashboard backfill lane.
+*/
+const ACTIVE_PROCESSES_KEY = Symbol.for("fusion.plugin.omp-runtime.activeProcesses");
+const processWithActiveProcesses = process as typeof process & {
+  [key: symbol]: Set<ChildProcess> | undefined;
+};
+
 /** Registry of active agent subprocesses for teardown. Self-cleans on exit. */
-const activeProcesses = new Set<ChildProcess>();
+const activeProcesses =
+  processWithActiveProcesses[ACTIVE_PROCESSES_KEY] ??
+  (processWithActiveProcesses[ACTIVE_PROCESSES_KEY] = new Set<ChildProcess>());
 
 /**
  * Register a subprocess in the agent process registry.

plugins/fusion-plugin-omp-runtime/src/index.ts

@@ -17,9 +17,20 @@ download or bundle it. Upstream: https://omp.sh/docs/acp
 https://github.com/can1357/oh-my-pi
 */
 
-// Reap OMP ACP agent subprocesses on hard process exit (registry SIGKILL is
-// authoritative). Scoped to ACP-tracked agent children only — never port 4040.
-process.on("exit", killAllProcesses);
+/*
+FNXC:ProcessLifecycle 2026-07-16-07:00:
+The dashboard backfill worker repeatedly evaluates this plugin through
+`vi.resetModules()` while retaining the process singleton. Install one exit
+listener per OMP lifecycle owner and use the process-shared registry in the
+ACP manager so it reaps children from every evaluation. Do not appease this
+with `setMaxListeners`; the listener must stay bounded.
+*/
+const PROCESS_EXIT_HOOK_KEY = Symbol.for("fusion.plugin.omp-runtime.exitCleanup");
+const processWithExitHook = process as typeof process & { [key: symbol]: boolean | undefined };
+if (!processWithExitHook[PROCESS_EXIT_HOOK_KEY]) {
+  process.on("exit", killAllProcesses);
+  processWithExitHook[PROCESS_EXIT_HOOK_KEY] = true;
+}
 
 const plugin: FusionPlugin = definePlugin({
   manifest: {