fix(selfhost): isolate subscription cli environments

src/selfhost/ai.ts

@@ -104,17 +104,52 @@ export function createAnthropicAi(opts: { apiKey: string; model?: string | undef
 }
 
 // ── Subscription CLI providers (#979) — locally-authenticated `claude` / `codex` as a subprocess ──────────
-// SECURITY: the child env DELETES the billable API keys so a misconfigured CLI cannot silently bill the
-// metered API instead of using the subscription OAuth token. The CLI runs read-only / no extra tools. Any
-// non-zero exit / empty output / error-envelope THROWS so the caller degrades — never a silent answer.
-const BILLABLE_KEY_VARS = ["ANTHROPIC_API_KEY", "ANTHROPIC_AUTH_TOKEN", "CODEX_API_KEY", "OPENAI_API_KEY"] as const;
+// SECURITY: subscription CLIs get a strict allowlisted env, not the worker env. This keeps runtime
+// credentials out of prompt-injectable subprocesses while preserving CLI auth/home/proxy/cert settings. The CLI
+// runs read-only / no extra tools, and non-zero exit / empty output / error-envelope THROWS so the caller degrades.
+const SUBSCRIPTION_CLI_ENV_ALLOWLIST = [
+  "CODEX_HOME",
+  "HOME",
+  "HTTPS_PROXY",
+  "HTTP_PROXY",
+  "LANG",
+  "LC_ALL",
+  "NODE_EXTRA_CA_CERTS",
+  "NO_PROXY",
+  "PATH",
+  "SSL_CERT_DIR",
+  "SSL_CERT_FILE",
+  "TERM",
+  "XDG_CONFIG_HOME",
+  "XDG_DATA_HOME",
+  "XDG_STATE_HOME",
+  "https_proxy",
+  "http_proxy",
+  "no_proxy",
+] as const;
 
-function scrubBillableKeys(parent: Record<string, string | undefined>): Record<string, string | undefined> {
-  const child = { ...parent };
-  for (const k of BILLABLE_KEY_VARS) delete child[k];
+function subscriptionCliEnv(
+  parent: Record<string, string | undefined>,
+  extra: Record<string, string | undefined> = {},
+): Record<string, string | undefined> {
+  const child: Record<string, string | undefined> = {};
+  for (const key of SUBSCRIPTION_CLI_ENV_ALLOWLIST) {
+    const value = parent[key];
+    if (value !== undefined) child[key] = value;
+  }
+  for (const [key, value] of Object.entries(extra)) {
+    if (value !== undefined) child[key] = value;
+  }
   return child;
 }
 
+async function isolatedCliCwd(): Promise<string> {
+  const { mkdtemp } = await import("node:fs/promises");
+  const { tmpdir } = await import("node:os");
+  const { join } = await import("node:path");
+  return mkdtemp(join(tmpdir(), "gittensory-ai-"));
+}
+
 /** Pull the assistant's final text out of a CLI's JSON output (Claude Code `{result}` or Codex JSONL). */
 export function extractCliText(stdout: string): string {
   const trimmed = stdout.trim();
@@ -153,14 +188,18 @@ export function claudeErrorStatus(stdout: string): string | null {
   return null;
 }
 
-type SpawnFn = (cmd: string, args: string[], opts: { env: Record<string, string | undefined>; input?: string; timeoutMs: number }) => Promise<{ stdout: string; code: number | null }>;
+type SpawnFn = (
+  cmd: string,
+  args: string[],
+  opts: { env: Record<string, string | undefined>; input?: string; timeoutMs: number; cwd?: string },
+) => Promise<{ stdout: string; code: number | null }>;
 
 async function defaultSpawn(): Promise<SpawnFn> {
   const cp = await import("node:child_process");
   return (cmd, args, o) =>
     new Promise((resolve, reject) => {
       const stdio: ["pipe", "pipe", "pipe"] = ["pipe", "pipe", "pipe"];
-      const child = cp.spawn(cmd, args, { env: o.env as NodeJS.ProcessEnv, stdio });
+      const child = cp.spawn(cmd, args, { cwd: o.cwd, env: o.env as NodeJS.ProcessEnv, stdio });
       let stdout = "";
       /* v8 ignore start */ // a 120s subprocess timeout is not unit-testable without a 2-minute wait
       const timer = setTimeout(() => {
@@ -190,12 +229,15 @@ export function createClaudeCodeAi(parentEnv: Record<string, string | undefined>
     async run(model, options) {
       const token = parentEnv.CLAUDE_CODE_OAUTH_TOKEN;
       if (!token) throw new Error("claude_code_no_oauth_token");
-      const env = scrubBillableKeys(parentEnv);
-      env.CLAUDE_CODE_OAUTH_TOKEN = token;
+      const env = subscriptionCliEnv(parentEnv, { CLAUDE_CODE_OAUTH_TOKEN: token });
       const prompt = toMessages(options).map((m) => m.content).join("\n\n");
       const spawn = spawnImpl ?? (await defaultSpawn());
       const claudeModel = resolveModel(configuredModel(parentEnv), model, "sonnet");
-      const { stdout, code } = await spawn("claude", ["--print", "--output-format", "json", "--model", claudeModel, "--permission-mode", "plan", "--disallowedTools", "Bash,Edit,Write,WebFetch,WebSearch"], { env, input: prompt, timeoutMs: 120_000 });
+      const { stdout, code } = await spawn(
+        "claude",
+        ["--print", "--output-format", "json", "--model", claudeModel, "--permission-mode", "plan", "--disallowedTools", "Bash,Edit,Write,WebFetch,WebSearch"],
+        { env, input: prompt, timeoutMs: 120_000, cwd: await isolatedCliCwd() },
+      );
       if (code !== 0) throw new Error(`claude_code_exit_${code ?? "null"}`);
       const errStatus = claudeErrorStatus(stdout);
       if (errStatus) throw new Error(`claude_code_error_${errStatus}`);
@@ -212,7 +254,7 @@ export function createClaudeCodeAi(parentEnv: Record<string, string | undefined>
 export function createCodexAi(parentEnv: Record<string, string | undefined>, spawnImpl?: SpawnFn): SelfHostAi {
   return {
     async run(model, options) {
-      const env = scrubBillableKeys(parentEnv);
+      const env = subscriptionCliEnv(parentEnv);
       const prompt = toMessages(options).map((m) => m.content).join("\n\n");
       const spawn = spawnImpl ?? (await defaultSpawn());
       // codex 0.142+: `exec` is non-interactive — the old `--ask-for-approval` flag was REMOVED (passing it errors).
@@ -223,7 +265,11 @@ export function createCodexAi(parentEnv: Record<string, string | undefined>, spa
       const args = ["exec", "--json", "--skip-git-repo-check", "--sandbox", "read-only"];
       if (codexModel) args.push("--model", codexModel);
       args.push("--", prompt);
-      const { stdout, code } = await spawn("codex", args, { env, timeoutMs: 120_000 });
+      const { stdout, code } = await spawn("codex", args, {
+        env,
+        timeoutMs: 120_000,
+        cwd: await isolatedCliCwd(),
+      });
       if (code !== 0) throw new Error(`codex_exit_${code ?? "null"}`);
       const text = extractCliText(stdout);
       if (!text) throw new Error("codex_empty_output");

test/unit/selfhost-ai.test.ts

@@ -20,7 +20,11 @@ describe("resolveModel (#979 — never leak the Workers-AI default to a self-hos
 afterEach(() => vi.unstubAllGlobals());
 
 type SpawnResult = { stdout: string; code: number | null };
-type StubSpawn = (cmd: string, args: string[], opts: { env: Record<string, string | undefined>; input?: string; timeoutMs: number }) => Promise<SpawnResult>;
+type StubSpawn = (
+  cmd: string,
+  args: string[],
+  opts: { env: Record<string, string | undefined>; input?: string; timeoutMs: number; cwd?: string },
+) => Promise<SpawnResult>;
 
 describe("createOpenAiCompatibleAi (#979)", () => {
   it("POSTs to /chat/completions and returns { response }", async () => {
@@ -290,23 +294,40 @@ describe("subscription CLI helpers + fail-safe", () => {
       capturedEnv = o.env;
       return { stdout: JSON.stringify({ type: "result", result: "review text" }), code: 0 };
     };
-    const out = await createClaudeCodeAi({ CLAUDE_CODE_OAUTH_TOKEN: "t", ANTHROPIC_API_KEY: "sk-bill" }, stub).run("sonnet", { prompt: "x" });
+    const out = await createClaudeCodeAi({ CLAUDE_CODE_OAUTH_TOKEN: "t", ANTHROPIC_API_KEY: "sk-bill", WORKER_ONLY_VALUE: "internal" }, stub).run("sonnet", {
+      prompt: "x",
+    });
     expect(out.response).toBe("review text");
-    expect(capturedEnv.ANTHROPIC_API_KEY).toBeUndefined(); // scrubbed
+    expect(capturedEnv.ANTHROPIC_API_KEY).toBeUndefined(); // allowlisted subprocess env does not inherit metered API keys
+    expect(capturedEnv.WORKER_ONLY_VALUE).toBeUndefined();
     expect(capturedEnv.CLAUDE_CODE_OAUTH_TOKEN).toBe("t");
   });
 
   it("Codex: 0.142+ exec flags (no --ask-for-approval, has --skip-git-repo-check); --model only when configured", async () => {
     let seen: string[] = [];
-    const ok: StubSpawn = async (_cmd, args) => { seen = args; return { stdout: JSON.stringify({ type: "result", result: "codex review" }), code: 0 }; };
+    let capturedEnv: Record<string, string | undefined> = {};
+    let capturedCwd = "";
+    const ok: StubSpawn = async (_cmd, args, opts) => {
+      seen = args;
+      capturedEnv = opts.env;
+      capturedCwd = opts.cwd ?? "";
+      return { stdout: JSON.stringify({ type: "result", result: "codex review" }), code: 0 };
+    };
     // no configured model + the dual-router's empty model id → OMIT --model (codex picks the account default;
     // forcing e.g. gpt-5 fails on a ChatGPT-account login). And the removed --ask-for-approval must never appear.
-    expect((await createCodexAi({}, ok).run("", { prompt: "x" })).response).toBe("codex review");
+    expect(
+      (await createCodexAi({ PATH: "/bin", CODEX_HOME: "/tmp/codex", WORKER_ONLY_VALUE: "internal", OPENAI_API_KEY: "sk-bill" }, ok).run("", {
+        prompt: "x",
+      })).response,
+    ).toBe("codex review");
     expect(seen).toEqual(["exec", "--json", "--skip-git-repo-check", "--sandbox", "read-only", "--", "x"]);
     expect(seen).not.toContain("--ask-for-approval");
-    // an explicit model (AI_MODEL, or a `codex:<model>` reviewer id) IS passed through
+    expect(capturedEnv).toEqual({ CODEX_HOME: "/tmp/codex", PATH: "/bin" });
+    expect(capturedCwd).toContain("gittensory-ai-");
+    // an explicit model (AI_MODEL, or a `codex:<model>` reviewer id) IS passed through but not inherited as env.
     await createCodexAi({ AI_MODEL: "o4-mini" }, ok).run("", { prompt: "x" });
     expect(seen.join(" ")).toContain("--model o4-mini");
+    expect(capturedEnv.AI_MODEL).toBeUndefined();
     const bad: StubSpawn = async () => ({ stdout: "", code: 1 });
     await expect(createCodexAi({}, bad).run("", { prompt: "x" })).rejects.toThrow(/codex_exit_1/);
   });