claude-code - 💡(How to fix) Fix `claude agents` bg-spare workers crash on init in 2.1.143 (regression from 2.1.142)

Summary

In claude 2.1.143 on macOS arm64, every worker spawned via the --bg-spare mode crashes during init within ~60–300 ms. This breaks claude agents (the FleetView agents view), whose daemon keeps a pool of prewarmed bg-spare workers ready and immediately marks each newly spawned worker as (crashed). Downgrading to 2.1.142 resolves the issue. Main entrypoints (claude --version, claude --help, interactive claude sessions) work fine on 2.1.143 — only the --bg-spare code path is broken.

Environment

• claude version: 2.1.143 (Claude Code), Bun v1.3.14
• Platform: macOS 15 (Darwin 25.4.0), Apple Silicon (arm64)
• Binary: ~/.local/bin/claude → ~/.local/share/claude/versions/2.1.143

Reproduction

1. Have 2.1.143 installed.
2. Run claude agents to start the agents view.
3. Tail ~/.claude/daemon.log.

You will see a tight loop of:

``` [bg] bg spare spawned host pid=NNNNN [bg] bg claimed-spare <id> (spare|fleet) [bg] bg settled <id> (crashed) ```

with each spare crashing 60–300 ms after spawn. The view itself never gets a working worker.

When the spare process error surfaces, the stack trace is the minified Bun-bundled form:

``` exit 1 before init — ... at uSK (/$bunfs/root/src/entrypoints/cli.js:9092:233) at async SKO (/$bunfs/root/src/entrypoints/cli.js:19558:68) at async h4O (/$bunfs/root/src/entrypoints/cli.js:19595:313) Bun v1.3.14 (macOS arm64) ```

Workaround

Point the launcher symlink at 2.1.142:

```bash ln -sfn ~/.local/share/claude/versions/2.1.142 ~/.local/bin/claude ```

After killing the running `claude agents` + `claude daemon run` processes and relaunching, the daemon settles cleanly with no crashed spares.

Impact

`claude agents` is unusable on 2.1.143 — the view stays empty because no spare ever survives long enough to take work. Other claude invocations are unaffected, so this regression can slip past install- time smoke tests.