fix: prevent terminal corruption during background bun install

[code-yeongyu]

Summary

• recreate the closed fix: prevent terminal corruption during background bun install #2369 fix on top of current dev
• add a piped output mode to runBunInstallWithDetails() so background bun install no longer inherits the active terminal output
• update the auto-update checker and regression tests to use silent background installs and only surface captured logs on failure

Testing

• bun test src/cli/config-manager/bun-install.test.ts src/hooks/auto-update-checker/hook/background-update-check.test.ts
• bun run typecheck
• bun run build

Fixes #2238

---

Summary by cubic

Prevents terminal corruption by running background bun install in silent pipe mode. Adds output control to runBunInstallWithDetails() and updates the auto-update checker to use it, surfacing captured logs only on failure or timeout.

• Bug Fixes
  • Added outputMode ("inherit" | "pipe", default "inherit") to runBunInstallWithDetails(); in pipe mode, capture stdout/stderr via Bun stream-to-text.
  • Log captured output only when the install fails or times out; keep the active terminal clean otherwise.
  • Improved timeouts: kill hung processes, handle non-resolving exited, and return timedOut: true with a clear error.
  • Auto-update checker now calls runBunInstallWithDetails({ outputMode: "pipe" }) and logs failure messages.
  • Tests cover piped output, failures, and timeouts; added Bun type refs in both related test files.

^{Written for commit de2b073. Summary will update on new commits.}

[cubic-dev-ai]

1 issue found across 4 files

Confidence score: 3/5

• There is a concrete regression risk in src/cli/config-manager/bun-install.ts: the timeout handler still awaits process exit, which can permanently hang if the child process is stuck.
• Because this is a high-severity, high-confidence issue (7/10, 9/10) affecting timeout safety in CLI install flow, merge risk is moderate rather than minimal.
• Pay close attention to src/cli/config-manager/bun-install.ts - timeout logic can block indefinitely instead of failing fast.

Prompt for AI agents (unresolved issues)

Check if these issues are valid — if so, understand the root cause of each and fix them. If appropriate, use sub-agents to investigate and fix each issue separately.


<file name="src/cli/config-manager/bun-install.ts">

<violation number="1" location="src/cli/config-manager/bun-install.ts:106">
P1: Awaiting process exit unconditionally inside the timeout handler defeats the timeout's protection. If the process is stuck, this causes a permanent hang.

To safely log the output without blocking the timeout return, handle the promise asynchronously.</violation>
</file>

_{Reply with feedback, questions, or to request a fix. Tag @cubic-dev-ai to re-run a review.}