fix(runner): bridge shared Codex Unix sessions

Co-Authored-By: Paperclip <noreply@paperclip.ing>

packages/paperclip-runner/package.json

@@ -6,6 +6,7 @@
   "type": "module",
   "bin": {
     "paperclip-runner-eval-session": "./dist/cli/eval-session.js",
+    "paperclip-runner-codex-proxy": "./dist/cli/codex-app-server-unix-proxy.js",
     "paperclip-runner-opencode-proxy": "./dist/cli/opencode-app-server-proxy.js",
     "paperclip-runner-acpx-sidecar": "./dist/cli/acpx-runtime-sidecar.js"
   },

packages/paperclip-runner/src/cli/codex-app-server-unix-proxy.ts

@@ -0,0 +1,24 @@
+#!/usr/bin/env node
+import { createConnection } from "node:net";
+
+function socketArgument(argv: string[]): string {
+  const index = argv.indexOf("--socket");
+  const value = index >= 0 ? argv[index + 1] : undefined;
+  if (!value) throw new Error("--socket requires a Unix socket path");
+  return value;
+}
+
+try {
+  const socket = createConnection(socketArgument(process.argv.slice(2)));
+  socket.once("connect", () => {
+    process.stdin.pipe(socket);
+    socket.pipe(process.stdout);
+  });
+  socket.once("error", (error) => {
+    process.stderr.write(`Codex app-server socket error: ${error.message}\n`);
+    process.exitCode = 1;
+  });
+} catch (error) {
+  process.stderr.write(`${error instanceof Error ? error.message : String(error)}\n`);
+  process.exitCode = 1;
+}

packages/paperclip-runner/src/control-plane/durable-prp-control-plane.ts

@@ -2418,6 +2418,9 @@ export async function runDurableEvalSession(
   const acpxSidecarPath =
     input.acpxSidecarPath ??
     fileURLToPath(new URL("../cli/acpx-runtime-sidecar.js", import.meta.url));
+  const codexUnixProxyPath = fileURLToPath(
+    new URL("../cli/codex-app-server-unix-proxy.js", import.meta.url),
+  );
   const acpxProfile =
     providerKind === "acpx"
       ? resolveQualifiedAcpxProfile(input.acpxAgent ?? "pi", input.model)
@@ -2429,13 +2432,7 @@ export async function runDurableEvalSession(
     input.providerArgs ??
     (input.nativeResume === undefined
       ? providerArgs
-      : [
-          ...codexConfigArgs,
-          "app-server",
-          "proxy",
-          "--sock",
-          sharedCodexSocket,
-        ]);
+      : [codexUnixProxyPath, "--socket", sharedCodexSocket]);
   let sharedCodexServer: ChildProcessWithoutNullStreams | null = null;
   let sharedCodexServerStderr = "";
   let sharedCodexServerError: Error | null = null;
@@ -2483,7 +2480,9 @@ export async function runDurableEvalSession(
                 kind: providerKind,
                 command:
                   input.providerCommand ??
-                  (providerKind === "opencode"
+                  (input.nativeResume !== undefined
+                    ? process.execPath
+                    : providerKind === "opencode"
                     ? process.execPath
                     : (process.env.PAPERCLIP_CODEX_COMMAND ?? "codex")),
                 args: