Greptile Summary

This PR contains two separate bug fixes:

1. Browser stdio fix (chrome.ts): Changed Chrome spawn configuration from stdio: "pipe" to stdio: ["ignore", "ignore", "ignore"] to prevent buffer blocking in Docker environments. The codebase doesn't consume Chrome's stdout/stderr streams anywhere, so discarding them is safe and resolves the CDP timeout issue.

2. Null guard fix (usage.ts, session-cost-usage.ts): Added optional chaining and nullish coalescing to usage sort comparators to prevent crashes when totals is undefined. The fix prevents "Cannot read properties of undefined" errors in production.

Note: The PR title only mentions the browser fix, but includes the unrelated usage fix as well. According to the project's guidelines (CLAUDE.md), unrelated changes should typically be in separate PRs. Both fixes are valid, but bundling them may make the PR history harder to track.

Confidence Score: 4/5

• This PR is safe to merge with low risk
• Both fixes address real bugs and are technically correct. The stdio change is well-justified and doesn't break any existing functionality (verified that Chrome stdout/stderr are unused). The null guards are defensive programming that prevent actual crashes. Score is 4 instead of 5 due to: (1) bundling two unrelated fixes in one PR, which goes against project guidelines, and (2) missing test coverage for the fixes.
• No files require special attention

_{Last reviewed commit: 200f8c0}

This pull request has been automatically marked as stale due to inactivity.
Please add updates or it will be closed.

Note: the install-smoke failure blocking PR #31192 is the same src/browser/chrome.ts stdin type mismatch that this PR fixes. Merging this PR (#27899) should unblock #31192's CI as well.