fix: isolate codex home in worktrees

packages/adapters/codex-local/src/server/codex-home.ts

@@ -0,0 +1,101 @@
+import fs from "node:fs/promises";
+import os from "node:os";
+import path from "node:path";
+import type { AdapterExecutionContext } from "@paperclipai/adapter-utils";
+
+const TRUTHY_ENV_RE = /^(1|true|yes|on)$/i;
+const COPIED_SHARED_FILES = ["config.json", "config.toml", "instructions.md"] as const;
+const SYMLINKED_SHARED_FILES = ["auth.json"] as const;
+
+function nonEmpty(value: string | undefined): string | null {
+  return typeof value === "string" && value.trim().length > 0 ? value.trim() : null;
+}
+
+async function pathExists(candidate: string): Promise<boolean> {
+  return fs.access(candidate).then(() => true).catch(() => false);
+}
+
+export function resolveCodexHomeDir(env: NodeJS.ProcessEnv = process.env): string {
+  const fromEnv = nonEmpty(env.CODEX_HOME);
+  if (fromEnv) return path.resolve(fromEnv);
+  return path.join(os.homedir(), ".codex");
+}
+
+function isWorktreeMode(env: NodeJS.ProcessEnv): boolean {
+  return TRUTHY_ENV_RE.test(env.PAPERCLIP_IN_WORKTREE ?? "");
+}
+
+function resolveWorktreeCodexHomeDir(env: NodeJS.ProcessEnv): string | null {
+  if (!isWorktreeMode(env)) return null;
+  const paperclipHome = nonEmpty(env.PAPERCLIP_HOME);
+  if (!paperclipHome) return null;
+  const instanceId = nonEmpty(env.PAPERCLIP_INSTANCE_ID);
+  if (instanceId) {
+    return path.resolve(paperclipHome, "instances", instanceId, "codex-home");
+  }
+  return path.resolve(paperclipHome, "codex-home");
+}
+
+async function ensureParentDir(target: string): Promise<void> {
+  await fs.mkdir(path.dirname(target), { recursive: true });
+}
+
+async function ensureSymlink(target: string, source: string): Promise<void> {
+  const existing = await fs.lstat(target).catch(() => null);
+  if (!existing) {
+    await ensureParentDir(target);
+    await fs.symlink(source, target);
+    return;
+  }
+
+  if (!existing.isSymbolicLink()) {
+    return;
+  }
+
+  const linkedPath = await fs.readlink(target).catch(() => null);
+  if (!linkedPath) return;
+
+  const resolvedLinkedPath = path.resolve(path.dirname(target), linkedPath);
+  if (resolvedLinkedPath === source) return;
+
+  await fs.unlink(target);
+  await fs.symlink(source, target);
+}
+
+async function ensureCopiedFile(target: string, source: string): Promise<void> {
+  const existing = await fs.lstat(target).catch(() => null);
+  if (existing) return;
+  await ensureParentDir(target);
+  await fs.copyFile(source, target);
+}
+
+export async function prepareWorktreeCodexHome(
+  env: NodeJS.ProcessEnv,
+  onLog: AdapterExecutionContext["onLog"],
+): Promise<string | null> {
+  const targetHome = resolveWorktreeCodexHomeDir(env);
+  if (!targetHome) return null;
+
+  const sourceHome = resolveCodexHomeDir(env);
+  if (path.resolve(sourceHome) === path.resolve(targetHome)) return targetHome;
+
+  await fs.mkdir(targetHome, { recursive: true });
+
+  for (const name of SYMLINKED_SHARED_FILES) {
+    const source = path.join(sourceHome, name);
+    if (!(await pathExists(source))) continue;
+    await ensureSymlink(path.join(targetHome, name), source);
+  }
+
+  for (const name of COPIED_SHARED_FILES) {
+    const source = path.join(sourceHome, name);
+    if (!(await pathExists(source))) continue;
+    await ensureCopiedFile(path.join(targetHome, name), source);
+  }
+
+  await onLog(
+    "stderr",
+    `[paperclip] Using worktree-isolated Codex home "${targetHome}" (seeded from "${sourceHome}").\n`,
+  );
+  return targetHome;
+}