[Marukome0743]

Summary

• stop retaining all stdout and stderr for every non-raw command execution
• retain only the last 64 KiB of hidden stdout for progress-mode failure diagnostics
• preserve live output, redaction, artifact-cache capture, keep-order buffering, and process cleanup behavior

Root cause

CmdLineRunner appended every redacted stdout and stderr line to combined_output in both its synchronous and asynchronous execution paths. Most output modes never consumed that vector, including the default parallel prefix mode, so long-running services accumulated output for their entire lifetime. In a local reproduction with a continuously writing task and a second parallel task, mise RSS grew from about 374 MiB after one second to about 1.97 GiB after six seconds.

The runner now creates a failure-output buffer only when stdout is hidden behind a progress reporter and therefore needs to be replayed on failure. That buffer keeps a UTF-8-safe 64 KiB tail and emits a truncation notice when older output is discarded.

Verification

• mise exec -- cargo test --all-features cmd::tests (21 passed)
• mise run test:e2e e2e/tasks/test_task_output_buffering
• mise run test:e2e e2e/tasks/test_task_parallel_replacing e2e/tasks/test_task_output_style_decoupling e2e/tasks/test_task_raw_output e2e/tasks/test_task_artifact_cache_output e2e/tasks/test_task_parallel_fail_fast
• mise exec -- cargo check --all-features
• mise exec -- cargo clippy --workspace --all-features --all-targets -- -D warnings
• mise exec -- cargo fmt --all -- --check
• mise exec -- shellcheck e2e/tasks/test_task_output_buffering
• mise exec -- shfmt -d e2e/tasks/test_task_output_buffering

mise run lint could not run because its hk task requires a .git directory, while this checkout is managed by Sapling without one; the underlying Rust, shell, and format checks above passed directly.

Addresses #8786

AI-assisted — Tool: Codex; model: OpenAI/GPT-5; version: unavailable.

Summary by CodeRabbit

• Bug Fixes

  • Improved failed-command output handling by retaining the most recent output when earlier content exceeds the buffer limit.
  • Added a truncation notice when older output is discarded.
  • Preserved safe handling of Unicode text and parallel task output streams.

• Tests

  • Added regression coverage for buffered output, truncation behavior, and failed-command reporting.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository YAML (base), Central YAML (inherited), Organization UI (inherited)

Review profile: CHILL

Plan: Pro Plus

Run ID: ac5b6dae-e5a1-4ada-9498-9ad57579f1f1

📥 Commits

Reviewing files that changed from the base of the PR and between 5cc4893 and f71c29a.

📒 Files selected for processing (2)

• e2e/tasks/test_task_output_buffering
• src/cmd.rs

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📝 Walkthrough

Walkthrough

Changes

Failure output buffering

Layer / File(s)	Summary
Bounded failure-output collector src/cmd.rs	FailureOutputTail retains the final 64 KiB of stdout, truncates UTF-8 safely, reports truncation, and activates only for progress-hidden output without a stdout callback. Unit tests cover these rules.
Synchronous command handling src/cmd.rs	Synchronous execution streams stdout and stderr directly and replays only the retained stdout tail when a command fails.
Asynchronous command handling and regression coverage src/cmd.rs, e2e/tasks/test_task_output_buffering	Asynchronous execution applies the same bounded retention during output and pipe draining. End-to-end coverage verifies parallel streaming and truncated failure output.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Sequence Diagram(s)

sequenceDiagram
  participant CmdLineRunner
  participant ChildCommand
  participant ProgressReport
  participant ErrorHandler
  CmdLineRunner->>ChildCommand: Execute command
  ChildCommand->>ProgressReport: Stream stdout
  ChildCommand->>CmdLineRunner: Stream stderr
  CmdLineRunner->>CmdLineRunner: Retain bounded stdout tail
  ChildCommand-->>CmdLineRunner: Return failure
  CmdLineRunner->>ErrorHandler: Replay retained tail and truncation notice

Loading

Possibly related PRs

• jdx/mise#11347: Both change src/cmd.rs output capture paths.
• jdx/mise#11381: Both modify CmdLineRunner stream buffering.
• jdx/mise#11511: Both modify synchronous and asynchronous command execution paths.

Suggested reviewers: jdx, jambalaya56562, risu729

Poem

I’m a rabbit guarding the tail,
Sixty-four KiB in my leafy pail.
Streams run freely, lines stay bright,
Failed commands replay the final sight.
UTF-8 hops safely through the night.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: limiting buffered command output for task failures.

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[greptile-apps]

Greptile Summary

This PR bounds hidden command-output retention while preserving live stream handling and failure diagnostics.

• Adds a UTF-8-safe 64 KiB tail buffer for stdout hidden behind progress reporting.
• Stops accumulating unused stdout and stderr in synchronous and asynchronous command execution.
• Adds unit and end-to-end coverage for bounded retention, truncation notices, Unicode, and parallel output.

Confidence Score: 5/5

The PR appears safe to merge, with no concrete changed-code defect identified.

The new buffer is enabled only for stdout hidden by progress reporting, bounds retained payload, truncates oversized UTF-8 lines safely, and leaves stderr visible through its existing live progress-report path.

Important Files Changed

Filename	Overview
src/cmd.rs	Replaces unbounded combined-output accumulation with a bounded hidden-stdout tail while retaining existing stream and error-routing behavior.
e2e/tasks/test_task_output_buffering	Adds regression coverage for streamed parallel output and truncated failure diagnostics in replacing mode.

_{Reviews (1): Last reviewed commit: "fix(task): bound buffered command output" | Re-trigger Greptile}