fix(durable): resolve Pi host peers in managed installs

docs/durable-pi.md

@@ -11,7 +11,10 @@ alias), because Pi-managed installs deliberately omit host-provided peers.
 Only the durable worker maps Pi imports to that SDK and its dependencies; the
 extension continues to use Main's host modules. If a partial/older installation
 reports a missing worker SDK, reinstall or update Fabric to restore its runtime
-dependencies. Installing Pi peers manually is not required.
+dependencies. Installing Pi peers manually is not required. When Bun launches
+the parent worker, the durable SDK host runs through `node` on PATH and requires
+Node.js 24+, matching Fabric's declared engine. This keeps module resolution
+isolated without passing `NODE_PATH` to tools or borrowing Main's SDK.
 
 Set `agents.runner: "pi"` (or `runner: "pi"` per request) for the previous Pi CLI
 worker. Existing explicit configurations and stored actor runners are not

src/durable/worker.ts

@@ -1,31 +1,45 @@
 #!/usr/bin/env node
-import { registerHooks } from "node:module";
+import { spawn } from "node:child_process";
+import module from "node:module";
+import { fileURLToPath } from "node:url";
 import { parseDurableWorkerOptions } from "./worker-options.js";
 
 try {
   // This process-only entry is never imported by extension registration.
   const options = parseDurableWorkerOptions(process.argv.slice(2));
-  // Managed Pi installs omit host peers. A subprocess cannot use Main's virtual
-  // modules, so it owns a pinned SDK under a non-peer name. Resolve all Pi peers
-  // through that SDK's dependency tree (also with non-hoisting installers), not
-  // an ambient checkout or another extension's SDK. This hook is process-local
-  // and must be installed before importing any durable host/engine modules.
-  const sdkEntry = import.meta.resolve("pi-fabric-worker-sdk");
-  const sdkName = "@earendil-works/pi-coding-agent";
-  const peers = ["@earendil-works/pi-agent-core", "@earendil-works/pi-ai", "@earendil-works/pi-tui", "typebox"];
-  registerHooks({
-    resolve(specifier, context, nextResolve) {
-      if (specifier === sdkName || specifier.startsWith(`${sdkName}/`)) {
-        return nextResolve(`pi-fabric-worker-sdk${specifier.slice(sdkName.length)}`, { ...context, parentURL: import.meta.url });
-      }
-      if (peers.some(name => specifier === name || specifier.startsWith(`${name}/`))) {
-        return nextResolve(specifier, { ...context, parentURL: sdkEntry });
-      }
-      return nextResolve(specifier, context);
-    },
-  });
-  const { runDurableWorker } = await import("./worker-host.js");
-  await runDurableWorker(options);
+  if (process.versions.bun) {
+    // Bun cannot install Node's peer-resolution hooks. Keep the pinned SDK in
+    // the package's required Node 24+ runtime; never inject ambient NODE_PATH.
+    const child = spawn("node", [fileURLToPath(import.meta.url), ...process.argv.slice(2)], { stdio: "inherit" });
+    const code = await new Promise<number>((resolve, reject) => {
+      child.once("error", error => reject(new Error(`Bun-launched durable workers require Node.js 24+ on PATH: ${error.message}`, { cause: error })));
+      child.once("exit", (code, signal) => resolve(code ?? (signal ? 1 : 0)));
+    });
+    process.exitCode = code;
+  } else {
+    if (Number.parseInt(process.versions.node, 10) < 24) throw new Error("Durable Pi workers require Node.js 24+");
+    // Managed Pi installs omit host peers. A subprocess cannot use Main's virtual
+    // modules, so it owns a pinned SDK under a non-peer name. Resolve all Pi peers
+    // through that SDK's dependency tree (also with non-hoisting installers), not
+    // an ambient checkout or another extension's SDK. This hook is process-local
+    // and must be installed before importing any durable host/engine modules.
+    const sdkEntry = import.meta.resolve("pi-fabric-worker-sdk");
+    const sdkName = "@earendil-works/pi-coding-agent";
+    const peers = ["@earendil-works/pi-agent-core", "@earendil-works/pi-ai", "@earendil-works/pi-tui", "typebox"];
+    module.registerHooks({
+      resolve(specifier, context, nextResolve) {
+        if (specifier === sdkName || specifier.startsWith(`${sdkName}/`)) {
+          return nextResolve(`pi-fabric-worker-sdk${specifier.slice(sdkName.length)}`, { ...context, parentURL: import.meta.url });
+        }
+        if (peers.some(name => specifier === name || specifier.startsWith(`${name}/`))) {
+          return nextResolve(specifier, { ...context, parentURL: sdkEntry });
+        }
+        return nextResolve(specifier, context);
+      },
+    });
+    const { runDurableWorker } = await import("./worker-host.js");
+    await runDurableWorker(options);
+  }
 } catch (error) {
   process.stderr.write(`Durable Pi worker failed: ${error instanceof Error ? error.stack ?? error.message : String(error)}\n`);
   process.exitCode = 1;

tests/durable-worker-installation.test.ts

@@ -1,3 +1,6 @@
+import { execFile, spawnSync } from "node:child_process";
+import { promisify } from "node:util";
+import type { AgentRunRecord } from "../src/agents/types.js";
 import fs from "node:fs";
 import os from "node:os";
 import path from "node:path";
@@ -56,7 +59,34 @@ function installation() {
   return { root, manager };
 }
 
+const bunAvailable = spawnSync("bun", ["--version"], { timeout: 5000 }).status === 0;
+
 describe("installed durable worker without host peers", () => {
+  it.skipIf(!bunAvailable)("runs the parent and durable SDK worker under Bun without host peers", async () => {
+    const { root } = installation();
+    const taskFile = path.join(root, "task.txt");
+    const statusFile = path.join(root, "bun-status.json");
+    fs.writeFileSync(taskFile, "read fixture");
+    const flags = {
+      id: "bun-probe", name: "bun-probe", runner: "pi-durable", cwd: root,
+      "task-file": taskFile, "status-file": statusFile,
+      "lifecycle-file": path.join(root, "bun-lifecycle.jsonl"), "log-file": path.join(root, "bun-events.jsonl"),
+      "pi-binary": "forbidden-legacy-fallback", "claude-binary": "unused", "veda-binary": "unused",
+      "veda-backend": "agy", "veda-persona": "unused", "timeout-ms": "20000", depth: "1",
+      "full-code-mode": "false", extensions: "true", tools: '["read"]', "granted-risks": "[]", transport: "process",
+    };
+    const child = await promisify(execFile)("bun", [path.join(root, "dist/worker.js"),
+      ...Object.entries(flags).flatMap(([key, value]) => [`--${key}`, value])],
+    { cwd: root, timeout: 25000, maxBuffer: 100000 }).then(
+      output => ({ ...output, exitCode: 0 }), error => ({ stderr: String(error.stderr), exitCode: error.code }),
+    );
+    expect(child, child.stderr).toMatchObject({ exitCode: 0 });
+    const record = JSON.parse(fs.readFileSync(statusFile, "utf8")) as AgentRunRecord;
+    expect(record.status, record.error).toBe("completed");
+    expect(record.text).toContain("installed durable worker works");
+    expect(record.toolCalls).toBe(1);
+  }, 30000);
+
   it("runs SDK RPC, a discovered extension, and a real tool outside the checkout", async () => {
     const { manager } = installation();
     const result = await manager.run({ task: "read fixture", tools: ["read"] });