パイプ先が早期に閉じても broken pipe でパニックしない

[TwoSquirrels]

Fixes #62

変更内容

• src/output.rs を新設し、stdout への書き込みを一箇所に集約。ErrorKind::BrokenPipe は静かに正常終了 (exit(0)) し、それ以外の書き込み失敗のみ従来通りパニックする。
• bundle.rs の print! (出力量が最も大きく実害の中心) をこの経路に差し替え。
• library.rs の println! (list/show 等) も同様に差し替え、| head 等のパイプ運用への耐性を揃えた。

テスト

• broken_pipe_while_writing_output_does_not_panic を追加。main.cpp 自身をコメントで肥大化させて出力サイズを稼ぎ (ライブラリやコンパイラ固有の機能に頼らない)、パイプを早期に閉じても stderr に panicked が出ないことを確認する。
• 修正前のコードに対して実際にこのテストが失敗する (パニックを再現する) ことを手元で確認済み。
• cargo fmt --check / cargo clippy --all-targets --all-features -- -D warnings / cargo test --all-features すべて通過。

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes

  • Improved command output handling when output is redirected or consumed by another process.
  • Prevented broken-pipe scenarios from producing panic messages or unnecessary failures.
  • Standardized output behavior across bundling and library management commands.

• Tests

  • Added coverage for bundling when the output stream closes unexpectedly.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 1bac9334-02c3-41ca-b639-71b4454b7ba4

📥 Commits

Reviewing files that changed from the base of the PR and between efe9415 and a863eaf.

📒 Files selected for processing (5)

• src/commands/bundle.rs
• src/commands/library.rs
• src/main.rs
• src/output.rs
• tests/cli.rs

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📝 Walkthrough

Walkthrough

The CLI introduces centralized stdout helpers that handle broken pipes cleanly. Bundle and library commands now use these helpers, with an end-to-end test covering early stdout closure.

Changes

CLI output handling

Layer / File(s)	Summary
Central stdout writer src/main.rs, src/output.rs	Adds shared write and write_line helpers; broken-pipe errors exit successfully while other write errors panic.
Command output integration src/commands/bundle.rs, src/commands/library.rs, tests/cli.rs	Routes bundle and library messages through the shared writers and adds a subprocess test for broken-pipe output.

Estimated code review effort: 2 (Simple) | ~10 minutes

Possibly related PRs

• TwoSquirrels/risundle#17: Overlaps with library show and show_field output formatting.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the core fix: avoiding broken-pipe panics when the pipe closes early.
Linked Issues check	✅ Passed	The PR implements silent BrokenPipe exit, reroutes CLI output through helpers, and adds a regression test for early pipe closure.
Out of Scope Changes check	✅ Passed	The changes stay focused on stdout handling and the regression test, with no unrelated feature work.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/broken-pipe-panic

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