From 7372769dcee563653cdfd95c370626cf6d2922c7 Mon Sep 17 00:00:00 2001
From: garrytan <garrytan@gmail.com>
Date: Sat, 3 Oct 2026 20:34:05 +0000
Subject: [PATCH] D0: keep a project's .env and bunfig.toml out of compiled
 binaries and daemon children

Compiled binaries are built with --no-compile-autoload-dotenv and
--no-compile-autoload-bunfig; the browse server and terminal agent are
spawned with --no-env-file and an empty config, so a repo's .env cannot set
GSTACK_CHROMIUM_NO_SANDBOX and a bunfig preload cannot run code in them.
Verified on Bun 1.4.0.
---
 browse/src/cli.ts                    |   4 +-
 browse/src/terminal-agent-control.ts |   9 +-
 browse/test/dotenv-isolation.test.ts | 120 +++++++++++++++++++++++++++
 scripts/build.sh                     |  13 +--
 4 files changed, 138 insertions(+), 8 deletions(-)
 create mode 100644 browse/test/dotenv-isolation.test.ts

diff --git a/browse/src/cli.ts b/browse/src/cli.ts
index fe44feaf7..54a8c35c9 100644
--- a/browse/src/cli.ts
+++ b/browse/src/cli.ts
@@ -18,7 +18,7 @@ import { writeSecureFile, mkdirSecure } from './file-permissions';
 import { resolveConfig, ensureStateDir, readVersionHash, isPairAgentEnabled, resolveChromiumProfile } from './config';
 import { parseProxyConfig, computeConfigHash, ProxyConfigError } from './proxy-config';
 import { redactProxyUrl } from './proxy-redact';
-import { spawnTerminalAgent } from './terminal-agent-control';
+import { spawnTerminalAgent, BUN_CHILD_FLAGS } from './terminal-agent-control';
 // Zero side effects on import (documented invariant in token-registry.ts) —
 // safe to pull the shared pairing default into the CLI.
 import { DEFAULT_PAIR_SCOPES } from './token-registry';
@@ -658,7 +658,7 @@ async function startServer(extraEnv?: Record<string, string>): Promise<ServerSta
     // (PPID=1, STAT=Ss) and survives the spawning shell's exit. Mirrors
     // the Windows path's rationale — same root cause, different OS API.
     const daemonLogFd = openDaemonLogSink();
-    const child = nodeSpawn('bun', ['run', SERVER_SCRIPT], {
+    const child = nodeSpawn('bun', [...BUN_CHILD_FLAGS, 'run', SERVER_SCRIPT], {
       detached: true,
       windowsHide: true,
       stdio: ['ignore', daemonLogFd, daemonLogFd],
diff --git a/browse/src/terminal-agent-control.ts b/browse/src/terminal-agent-control.ts
index 0b0ad1ac4..d64818a37 100644
--- a/browse/src/terminal-agent-control.ts
+++ b/browse/src/terminal-agent-control.ts
@@ -138,6 +138,13 @@ export function acquireAgentStateLock(stateDir: string, waitMs = 5000, publicati
  * exposes it relative to process.execPath. Either path must work or
  * the agent can't be spawned at all.
  */
+/**
+ * Flags for every `bun run` child the daemon spawns. The child runs in the
+ * user's project, and Bun would otherwise load that project's .env (which can
+ * set GSTACK_CHROMIUM_NO_SANDBOX) and bunfig.toml (whose preload runs code).
+ */
+export const BUN_CHILD_FLAGS = ['--no-env-file', `--config=${process.platform === 'win32' ? 'NUL' : '/dev/null'}`];
+
 export function resolveTerminalAgentScript(searchHints: { metaDir?: string; execPath?: string } = {}): string | null {
   const meta = searchHints.metaDir || __dirname;
   const exec = searchHints.execPath || process.execPath;
@@ -197,7 +204,7 @@ export function spawnTerminalAgent(opts: {
     writeAgentRecord(stateDir, reservation);
     let proc: any;
     try {
-      proc = (Bun as any).spawn(['bun', 'run', script, `--agent-gen=${gen}`], {
+      proc = (Bun as any).spawn(['bun', ...BUN_CHILD_FLAGS, 'run', script, `--agent-gen=${gen}`], {
         cwd: opts.cwd || process.cwd(),
         env: {
           ...process.env,
diff --git a/browse/test/dotenv-isolation.test.ts b/browse/test/dotenv-isolation.test.ts
new file mode 100644
index 000000000..cd22bbd97
--- /dev/null
+++ b/browse/test/dotenv-isolation.test.ts
@@ -0,0 +1,120 @@
+/**
+ * D0: a project's .env and bunfig.toml must not reach gstack's binaries or
+ * the Bun children the browse daemon starts in that project. Dotenv could set
+ * GSTACK_CHROMIUM_NO_SANDBOX; a bunfig preload runs arbitrary code.
+ */
+import { afterEach, beforeEach, describe, expect, test } from 'bun:test';
+import * as fs from 'node:fs';
+import * as os from 'node:os';
+import * as path from 'node:path';
+import { spawnTerminalAgent } from '../src/terminal-agent-control';
+
+const ROOT = path.resolve(import.meta.dir, '..', '..');
+const CLI = path.join(ROOT, 'browse', 'src', 'cli.ts');
+
+let project: string;
+let marker: string;
+
+function seedHostileProject(dir: string): void {
+  fs.mkdirSync(dir, { recursive: true });
+  fs.writeFileSync(path.join(dir, '.env'), 'GSTACK_CHROMIUM_NO_SANDBOX=1\n');
+  fs.writeFileSync(path.join(dir, 'preload.ts'), `require('node:fs').writeFileSync(${JSON.stringify(marker)}, 'ran');\n`);
+  fs.writeFileSync(path.join(dir, 'bunfig.toml'), 'preload = ["./preload.ts"]\n');
+}
+
+function probeSource(out: string): string {
+  return `require('node:fs').writeFileSync(${JSON.stringify(out)}, JSON.stringify({ sandbox: process.env.GSTACK_CHROMIUM_NO_SANDBOX ?? null }));\n`;
+}
+
+async function waitForFile(file: string): Promise<string> {
+  const deadline = Date.now() + 20_000;
+  while (!fs.existsSync(file) && Date.now() < deadline) await Bun.sleep(50);
+  return fs.readFileSync(file, 'utf-8');
+}
+
+beforeEach(() => {
+  const scratch = fs.mkdtempSync(path.join(os.tmpdir(), 'browse-dotenv-'));
+  project = path.join(scratch, 'project');
+  marker = path.join(scratch, 'preload-ran');
+  seedHostileProject(project);
+});
+
+afterEach(() => {
+  fs.rmSync(path.dirname(project), { recursive: true, force: true });
+});
+
+describe('D0: project .env and bunfig.toml are ignored', () => {
+  test('every compiled binary in scripts/build.sh turns dotenv and bunfig autoload off, and the flags work', () => {
+    const lines = fs.readFileSync(path.join(ROOT, 'scripts', 'build.sh'), 'utf-8').split('\n').filter(l => /build --compile/.test(l));
+    expect(lines.length).toBeGreaterThanOrEqual(5);
+    for (const line of lines) {
+      expect(line).toContain('--no-compile-autoload-dotenv');
+      expect(line).toContain('--no-compile-autoload-bunfig');
+    }
+    const out = path.join(path.dirname(project), 'probe.json');
+    const src = path.join(path.dirname(project), 'probe.ts');
+    const bin = path.join(path.dirname(project), 'probe-bin');
+    fs.writeFileSync(src, probeSource(out));
+    const build = Bun.spawnSync([process.execPath, 'build', '--compile', '--no-compile-autoload-dotenv', '--no-compile-autoload-bunfig', src, '--outfile', bin], { stdout: 'pipe', stderr: 'pipe', timeout: 60_000 });
+    expect(build.exitCode, build.stderr.toString()).toBe(0);
+    const run = Bun.spawnSync([bin], { cwd: project, env: { PATH: process.env.PATH ?? '' }, stdout: 'pipe', stderr: 'pipe', timeout: 30_000 });
+    expect(run.exitCode, run.stderr.toString()).toBe(0);
+    expect(JSON.parse(fs.readFileSync(out, 'utf-8'))).toEqual({ sandbox: null });
+    expect(fs.existsSync(marker)).toBe(false);
+  }, 90_000);
+
+  test('the terminal agent spawned in the project sees neither the .env value nor the bunfig preload', async () => {
+    const stateDir = path.join(path.dirname(project), 'state');
+    fs.mkdirSync(stateDir, { recursive: true });
+    const out = path.join(stateDir, 'agent-env.json');
+    const script = path.join(stateDir, 'agent-probe.ts');
+    fs.writeFileSync(script, probeSource(out));
+    const saved = process.env.GSTACK_CHROMIUM_NO_SANDBOX;
+    delete process.env.GSTACK_CHROMIUM_NO_SANDBOX;
+    try {
+      const pid = spawnTerminalAgent({ stateFile: path.join(stateDir, 'browse.json'), serverPort: 1, ownerPid: process.pid, cwd: project, scriptPath: script });
+      expect(pid).toBeGreaterThan(0);
+      expect(JSON.parse(await waitForFile(out))).toEqual({ sandbox: null });
+      expect(fs.existsSync(marker)).toBe(false);
+    } finally {
+      if (saved !== undefined) process.env.GSTACK_CHROMIUM_NO_SANDBOX = saved;
+    }
+  }, 30_000);
+
+  test.skipIf(process.platform === 'win32')('the browse server spawned from the project sees neither the .env value nor the bunfig preload', async () => {
+    const stateFile = path.join(project, '.gstack', 'browse.json');
+    const stub = path.join(path.dirname(project), 'stub-server.ts');
+    fs.writeFileSync(stub, `
+      import * as fs from 'node:fs';
+      const server = Bun.serve({ hostname: '127.0.0.1', port: 0, fetch: () => Response.json({ status: 'healthy' }) });
+      fs.writeFileSync(process.env.BROWSE_STATE_FILE!, JSON.stringify({
+        pid: process.pid, port: server.port, token: 'dotenv-test', mode: 'launched',
+        sandbox: process.env.GSTACK_CHROMIUM_NO_SANDBOX ?? null,
+      }));
+      setTimeout(() => process.exit(0), 5000);
+    `);
+    const env: Record<string, string> = {};
+    for (const [key, value] of Object.entries(process.env)) {
+      if (value !== undefined && !/^(BROWSE_|GSTACK_|CHROMIUM_PROFILE$|CLAUDE_PLUGIN_DATA$)/.test(key)) env[key] = value;
+    }
+    Object.assign(env, {
+      HOME: path.dirname(project),
+      GSTACK_HOME: path.join(path.dirname(project), '.gstack'),
+      BROWSE_STATE_FILE: stateFile,
+      BROWSE_SERVER_SCRIPT: stub,
+      BROWSE_PARENT_PID: '0',
+      BROWSE_START_TIMEOUT: '20000',
+    });
+    // The shipped CLI is compiled without dotenv autoload; --no-env-file gives
+    // the source CLI the same starting environment.
+    const cli = Bun.spawn([process.execPath, '--no-env-file', '--config=/dev/null', CLI, 'status'], { cwd: project, env, stdout: 'pipe', stderr: 'pipe' });
+    const timer = setTimeout(() => cli.kill('SIGKILL'), 40_000);
+    const [code, stderr] = await Promise.all([cli.exited, new Response(cli.stderr).text()]);
+    clearTimeout(timer);
+    const state = JSON.parse(fs.readFileSync(stateFile, 'utf-8'));
+    try { process.kill(state.pid, 'SIGKILL'); } catch {}
+    expect(code, stderr).toBe(0);
+    expect(state.sandbox).toBeNull();
+    expect(fs.existsSync(marker)).toBe(false);
+  }, 60_000);
+});
diff --git a/scripts/build.sh b/scripts/build.sh
index 559e5d807..bd34f55d3 100755
--- a/scripts/build.sh
+++ b/scripts/build.sh
@@ -30,13 +30,16 @@ case "$(uname -s)" in
     ;;
 esac
 
+# A project's .env or bunfig.toml must never reach the shipped binaries: they run
+# inside untrusted repos, and dotenv could set security switches such as
+# GSTACK_CHROMIUM_NO_SANDBOX while a bunfig preload runs arbitrary code (D0).
 "$BUN_CMD" run vendor:xterm
 "$BUN_CMD" run gen:skill-docs --host all
-"$BUN_CMD" build --compile browse/src/cli.ts --outfile browse/dist/browse
-"$BUN_CMD" build --compile browse/src/find-browse.ts --outfile browse/dist/find-browse
-"$BUN_CMD" build --compile design/src/cli.ts --outfile design/dist/design
-"$BUN_CMD" build --compile make-pdf/src/cli.ts --outfile make-pdf/dist/pdf
-"$BUN_CMD" build --compile bin/gstack-global-discover.ts --outfile bin/gstack-global-discover
+"$BUN_CMD" build --compile --no-compile-autoload-dotenv --no-compile-autoload-bunfig browse/src/cli.ts --outfile browse/dist/browse
+"$BUN_CMD" build --compile --no-compile-autoload-dotenv --no-compile-autoload-bunfig browse/src/find-browse.ts --outfile browse/dist/find-browse
+"$BUN_CMD" build --compile --no-compile-autoload-dotenv --no-compile-autoload-bunfig design/src/cli.ts --outfile design/dist/design
+"$BUN_CMD" build --compile --no-compile-autoload-dotenv --no-compile-autoload-bunfig make-pdf/src/cli.ts --outfile make-pdf/dist/pdf
+"$BUN_CMD" build --compile --no-compile-autoload-dotenv --no-compile-autoload-bunfig bin/gstack-global-discover.ts --outfile bin/gstack-global-discover
 if [ "${GSTACK_SETUP_RUNNING:-0}" = "1" ] && [ "${GSTACK_SETUP_SKIP_CSO_BUILD:-0}" = "1" ]; then
   # Setup removes these before invoking us too. Repeat here so the setup-private
   # escape hatch can never publish a completion stamp beside stale trusted code.