Check Code Quality

Rust Code Quality Checks

When to Use

• After completing significant code changes
• Before creating commits
• Before creating pull requests
• When user says "check code quality", "run quality checks", "make sure code is good", etc.

Quick Approach (Recommended)

Run the comprehensive check script which handles everything automatically:

./check.fish --full

This runs all checks in order: typecheck → build → clippy → tests → doctests → docs

Benefits of using check.fish --full:

• ICE recovery: Automatically cleans cache and retries on Internal Compiler Errors
• Toolchain escalation: If ICE persists, escalates to rust-toolchain-update.fish to find a stable nightly
• Config change detection: Auto-cleans stale artifacts when Cargo.toml or toolchain changes
• Performance optimized: Uses tmpfs, ionice, and parallel jobs for speed

Other check.fish Commands

For granular control, use individual commands:

Step-by-Step Approach (Alternative)

If you need more control or want to run checks manually:

1. Fast Typecheck

./check.fish --check
# (runs: cargo check)

Quickly verifies the code compiles without generating artifacts.

2. Compile Production Code

./check.fish --build
# (runs: cargo build)

Ensures production code builds successfully.

3. Format Rustdoc Comments

Invoke the write-documentation skill to format rustdoc comments using cargo rustdoc-fmt.

This formats markdown tables and converts inline links to reference-style.

4. Generate Documentation

./check.fish --quick-doc
# (runs: cargo doc --no-deps, directly to serving dir - fastest for iteration)

Verify there are no documentation build warnings or errors. Use --quick-doc for fast feedback during development. Use --doc for final verification before commits (includes staging/sync).

If there are link warnings, use the /fix-intradoc-links command to resolve them.

Heading Anchor (Slug) Integrity: If you modified any heading text (e.g., # My Heading), the automatically generated HTML anchor (e.g., #my-heading) will change.

• Identify Changes: Look for changed headings in git-dirty files.
• Proactive Search: Use grep_search to find any existing links (e.g., path#old-slug) that point to the old anchors and update them.
• Validation: While cargo doc warns about many broken fragments, proactive searching prevents "orphan" links in external documentation or complex intra-doc paths.

CRITICAL: Never remove intra-doc links to fix warnings. When you encounter:

• Unresolved link to a symbol → Fix the path using crate:: prefix (see write-documentation skill)
• Unresolved link to a test module → Add #[cfg(any(test, doc))] visibility (see organize-modules skill)
• Unresolved link to a platform-specific module → Use #[cfg(all(any(test, doc), target_os = "..."))]

Links provide refactoring safety - cargo doc catches stale references. Converting to plain backticks removes this protection.

5. Link Rot Check (External URLs)

Included automatically in ./check.fish --full. Runs lychee on git-modified files to detect broken external URLs in rustdoc comments.

cargo doc --no-deps (step 4) validates intra-doc links but not external HTTP/HTTPS URLs. lychee fills that gap. Config in lychee.toml (repo root) excludes known false positives (example file:// URIs, test fixture URLs, sites that block automated requests).

If lychee reports 404s, fix the URL by finding the new location. See the task file task/add-lychee-to-detect-link-rot.md for the full categorization of findings.

6. Linting

./check.fish --clippy
# or invoke the `run-clippy` skill

Runs clippy and enforces code style standards.

7. Run All Tests

./check.fish --test
# (runs: cargo test --all-targets && cargo test --doc)

Runs all tests (unit, integration, doctests).

If tests fail, use the Task tool with subagent_type='test-runner' to fix failures.

8. Stress Test (Optional - After Major Refactors)

After major refactors or changes that affect process spawning, PTY tests, or async infrastructure, run the full test suite 20 times back-to-back to detect flaky regressions:

for i in {1..20}; do echo "=== Run $i/20 ===" && cargo test --all-targets -- --nocapture 2>&1 | grep -E "^test result:" | head -3 || { echo "FAILED on run $i"; exit 1; }; done && echo "ALL 20 RUNS PASSED"

When to run:

• After refactoring PTY test infrastructure (generate_pty_test!, spawn_controlled_in_pty)
• After changes to process lifecycle, signal handling, or async I/O code
• After modifying the resilient reactor thread (RRT) restart logic
• Before merging large cross-cutting changes that touch many test files

9. Cross-Platform Verification (Optional)

For code with platform-specific #[cfg] gates (especially Unix-only code), verify Windows compatibility:

cargo rustc -p <crate_name> --target x86_64-pc-windows-gnu -- --emit=metadata

This checks that #[cfg(unix)] and #[cfg(not(unix))] gates compile correctly on Windows without needing a full cross-compiler toolchain.

When to run:

• After adding or modifying #[cfg(unix)] or #[cfg(target_os = "...")] attributes
• When working on platform-abstraction code
• Before committing changes to DirectToAnsi input handling or other Unix-specific code

ICE Recovery and Toolchain Escalation

The ./check.fish --full command includes automatic recovery from Internal Compiler Errors:

ICE detected → cleanup target/ → retry
                                   ↓
                            still ICE?
                                   ↓
              escalate to rust-toolchain-update.fish
              (searches 46 nightly candidates, validates each)
                                   ↓
                         new stable nightly installed
                                   ↓
                               retry checks

This is especially important since we use nightly Rust (for the parallel compiler frontend). Nightly toolchains occasionally have ICE bugs, and this automatic escalation finds a working version.

Reporting Results

After running all checks, report results concisely to the user:

• ✅ All checks passed → "All quality checks passed! Ready to commit."
• ⚠️ Some checks failed → Summarize which steps failed and what needs fixing
• 🔧 Auto-fixed issues → Report what was automatically fixed

Optional Performance Analysis

For performance-critical code changes, consider also running:

• cargo bench - Benchmarks (mark tests with #[bench])
• cargo flamegraph - Profiling (requires flamegraph crate)
• Invoke the analyze-performance skill for flamegraph-based regression detection

Supporting Files in This Skill

This skill includes additional reference material:

• reference.md - Comprehensive guide to all cargo commands used in the quality checklist. Includes detailed explanations of what each command does, when to use it, common flags, and build optimizations (wild linker, parallel frontend, tmpfs). Read this when:
  • You need to understand what a specific cargo command does
  • Troubleshooting build issues
  • Want to know about build optimizations in .cargo/config.toml
  • Understanding the difference between cargo test --all-targets and cargo test --doc

Related Skills

• write-documentation - For rustdoc formatting (step 3) and fixing doc link warnings (step 4)
• run-clippy - For linting and code style (step 5)
• analyze-performance - For optional performance checks
• test-runner agent - For fixing test failures (step 6)

Related Commands

• /check - Explicitly invokes this skill

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