chore: RFC-006 Phase 4 cleanup — delete worker-fork-support.ts

- Move formatChildExitSummary/formatCapturedStderrTail to worker-runtime.ts
- Move ignoreSessionBroadcastSignals to new worker-signals.ts
- Delete worker-fork-support.ts (teeCapturedStderr no longer used)
- Update .knowledge/worker-isolation.md and architecture.md for WorkerRuntime
- All 167 tests pass, biome check clean

Closes #283

packages/daemon/src/sense-worker.ts

@@ -25,7 +25,7 @@ import type { WorkerToParentMessage } from "./ipc.js";
 import { parseParentMessage } from "./ipc.js";
 import { executeCompute, loadSenseModule, openSenseDb } from "./sense-runtime.js";
 import type { SenseRuntime } from "./sense-runtime.js";
-import { ignoreSessionBroadcastSignals } from "./worker-fork-support.js";
+import { ignoreSessionBroadcastSignals } from "./worker-signals.js";
 
 // ---------------------------------------------------------------------------
 // IPC helpers

packages/daemon/src/worker-fork-support.ts

@@ -1,45 +0,0 @@
-import type { ChildProcess } from "node:child_process";
-
-const STDERR_TAIL_MAX_CHARS = 16_384;
-
-/**
- * Forked workers inherit the parent's process group. In foreground `nerve dev`,
- * terminal-driven SIGINT/SIGTERM is delivered to the whole group, so workers can exit
- * on the default handler before the kernel sends `{ type: "shutdown" }` over IPC.
- * Swallow these in worker processes so the parent coordinates shutdown (issue #55).
- * Only call when `process.send` is defined (fork IPC); standalone `node …-worker.js` keeps default Ctrl+C behaviour.
- */
-export function ignoreSessionBroadcastSignals(): void {
-  const swallow = (): void => {};
-  process.on("SIGINT", swallow);
-  process.on("SIGTERM", swallow);
-}
-
-export function teeCapturedStderr(child: ChildProcess, tail: { value: string }): void {
-  const stream = child.stderr;
-  if (stream === null || stream === undefined) return;
-  stream.setEncoding("utf8");
-  stream.on("data", (chunk: string | Buffer) => {
-    const text = typeof chunk === "string" ? chunk : chunk.toString("utf8");
-    process.stderr.write(text);
-    tail.value = (tail.value + text).slice(-STDERR_TAIL_MAX_CHARS);
-  });
-}
-
-export function formatChildExitSummary(code: number | null, signal: NodeJS.Signals | null): string {
-  const codeStr = code === null || code === undefined ? "null" : String(code);
-  if (signal) {
-    return `code=${codeStr} signal=${signal}`;
-  }
-  return `code=${codeStr}`;
-}
-
-export function formatCapturedStderrTail(tail: string, maxChars = 800): string {
-  const trimmed = tail.trim();
-  if (trimmed.length === 0) return "";
-  const normalized = trimmed.replace(/\r?\n/g, "\\n");
-  if (normalized.length <= maxChars) {
-    return ` worker_stderr=${normalized}`;
-  }
-  return ` worker_stderr=…${normalized.slice(-maxChars)}`;
-}

packages/daemon/src/worker-pool.ts

@@ -6,8 +6,11 @@ import { dirname, join } from "node:path";
 import { fileURLToPath } from "node:url";
 
 import type { ComputeMessage } from "./ipc.js";
-import { formatCapturedStderrTail, formatChildExitSummary } from "./worker-fork-support.js";
-import { createWorkerRuntime } from "./worker-runtime.js";
+import {
+  createWorkerRuntime,
+  formatCapturedStderrTail,
+  formatChildExitSummary,
+} from "./worker-runtime.js";
 
 export function resolveWorkerScript(): string {
   const __filename = fileURLToPath(import.meta.url);

packages/daemon/src/worker-runtime.ts

@@ -8,6 +8,24 @@ import { isPlainRecord } from "@uncaged/nerve-core";
 
 const STDERR_TAIL_MAX_CHARS = 2048;
 
+export function formatChildExitSummary(code: number | null, signal: NodeJS.Signals | null): string {
+  const codeStr = code === null || code === undefined ? "null" : String(code);
+  if (signal) {
+    return `code=${codeStr} signal=${signal}`;
+  }
+  return `code=${codeStr}`;
+}
+
+export function formatCapturedStderrTail(tail: string, maxChars = 800): string {
+  const trimmed = tail.trim();
+  if (trimmed.length === 0) return "";
+  const normalized = trimmed.replace(/\r?\n/g, "\\n");
+  if (normalized.length <= maxChars) {
+    return ` worker_stderr=${normalized}`;
+  }
+  return ` worker_stderr=…${normalized.slice(-maxChars)}`;
+}
+
 export type WorkerDrainOpts = {
   shutdownTimeoutMs: number | null;
 };

packages/daemon/src/worker-signals.ts

@@ -0,0 +1,17 @@
+/**
+ * Worker-process signal handling (fork IPC children only).
+ * Worker entrypoints import this module — not worker-runtime.ts (parent/kernel code).
+ */
+
+/**
+ * Forked workers inherit the parent's process group. In foreground `nerve dev`,
+ * terminal-driven SIGINT/SIGTERM is delivered to the whole group, so workers can exit
+ * on the default handler before the kernel sends `{ type: "shutdown" }` over IPC.
+ * Swallow these in worker processes so the parent coordinates shutdown (issue #55).
+ * Only call when `process.send` is defined (fork IPC); standalone `node …-worker.js` keeps default Ctrl+C behaviour.
+ */
+export function ignoreSessionBroadcastSignals(): void {
+  const swallow = (): void => {};
+  process.on("SIGINT", swallow);
+  process.on("SIGTERM", swallow);
+}

packages/daemon/src/workflow-manager.ts

@@ -11,8 +11,11 @@ import type { NerveConfig, WorkflowConfig, WorkflowStatus } from "@uncaged/nerve
 import type { LogStore } from "@uncaged/nerve-store";
 import type { KillThreadMessage, StartThreadMessage, ThreadEventMessage } from "./ipc.js";
 import { parseWorkerMessage } from "./ipc.js";
-import { formatCapturedStderrTail, formatChildExitSummary } from "./worker-fork-support.js";
-import { createWorkerRuntime } from "./worker-runtime.js";
+import {
+  createWorkerRuntime,
+  formatCapturedStderrTail,
+  formatChildExitSummary,
+} from "./worker-runtime.js";
 import {
   DEFAULT_MAX_QUEUE,
   WORKER_SHUTDOWN_TIMEOUT_MS,

packages/daemon/src/workflow-worker.ts

@@ -30,7 +30,7 @@ import type {
   WorkerToParentMessage,
 } from "./ipc.js";
 import { parseParentMessage } from "./ipc.js";
-import { ignoreSessionBroadcastSignals } from "./worker-fork-support.js";
+import { ignoreSessionBroadcastSignals } from "./worker-signals.js";
 
 // ---------------------------------------------------------------------------
 // IPC helpers