fix: pre-landing review fixes

The new dotenv-isolation test spawns Bun with emptyBunConfig() instead of a
literal --config=/dev/null, which the Windows lane cannot open; the runner's
timeout case asserts the descendant published a pid before asking whether it
is running, so a missed readiness window names itself.

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

browse/test/dotenv-isolation.test.ts

@@ -7,6 +7,7 @@ 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 { emptyBunConfig } from '../src/bun-child-config';
 import { spawnTerminalAgent } from '../src/terminal-agent-control';
 
 const ROOT = path.resolve(import.meta.dir, '..', '..');
@@ -60,7 +61,7 @@ describe('D0: project .env and bunfig.toml are ignored', () => {
     expect(JSON.parse(await waitForFile(out))).toEqual({ sandbox: null });
     const atomic = path.join(path.dirname(project), 'atomic.json');
     fs.writeFileSync(path.join(path.dirname(project), 'atomic-probe.ts'), probeSource(atomic));
-    const run = Bun.spawnSync([process.execPath, '--no-env-file', '--config=/dev/null', path.join(path.dirname(project), 'atomic-probe.ts')], { cwd: project, env: { PATH: process.env.PATH ?? '' }, stdout: 'pipe', stderr: 'pipe', timeout: 30_000 });
+    const run = Bun.spawnSync([process.execPath, '--no-env-file', `--config=${emptyBunConfig()}`, path.join(path.dirname(project), 'atomic-probe.ts')], { 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(atomic, 'utf-8'))).toEqual({ sandbox: null });
     expect(fs.existsSync(atomic + '.tmp')).toBe(false);

test/claude-code-runner.test.ts

@@ -306,7 +306,9 @@ describe('Claude Code restricted execution', () => {
       expect(fireTimeout).toBeDefined();
       const readyBy = Date.now() + 2000;
       while (publishedPid() === undefined && Date.now() < readyBy) await Bun.sleep(5);
-      expect(running(publishedPid()!)).toBe(true);
+      const descendantPid = publishedPid();
+      expect(descendantPid, 'descendant never published its pid within the readiness window').toBeDefined();
+      expect(running(descendantPid!)).toBe(true);
       const start = Date.now();
       const expire = fireTimeout!;
       fireTimeout = undefined;