Codecov Report

❌ Patch coverage is 78.21782% with 44 lines in your changes missing coverage. Please review.
✅ Project coverage is 63.77%. Comparing base (bd9d20a) to head (838575a).

@@            Coverage Diff             @@
##             main      #78      +/-   ##
==========================================
+ Coverage   63.53%   63.77%   +0.24%     
==========================================
  Files          65       66       +1     
  Lines       11898    12098     +200     
==========================================
+ Hits         7559     7716     +157     
- Misses       3546     3572      +26     
- Partials      793      810      +17     

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PR Review — feat: coroutine

Decision

Request Changes — Merge readiness blocked by missing PR description.

Merge Readiness Summary

The implementation is technically sound, well-tested, and properly documented in code. However, the PR description is empty — it contains only template headers with no actual content. For a 1000+ line feature addition, a proper description is required to explain the feature, its API, and its purpose before merge.

Blocking Findings

1. Missing PR Description

Issue: The PR body contains only template sections ("Changes Made", "Related Issues", "Additional Information") with no actual content.

Why it matters:

• Future maintainers won't have context about the design decisions
• Reviewers can't verify the PR matches the original requirement
• The PR title alone doesn't explain how coroutines work or why they matter

Minimal fix: Add a PR description that includes:

• What coroutines do (yield/resume suspension points for lightweight async patterns)
• Why they were added to minivm
• How the API works at a high level (coroutine-function call returns handle, RESUME continues, CORO_VALUE reads result)
• Any related issue/specification link
• Key design decisions (e.g., asymmetric yield/resume, why deopt on YIELD in inlined frames)

2. Missing Issue Link

Issue: The PR references no issue or specification document.

Recommendation: Link to the issue that prompted this feature.

Positive Findings

✅ Implementation is technically correct

• Suspension/resume semantics are sound
• Memory management is safe and refcount-correct
• GC properly roots active coroutines and captured frames
• Design decisions are sound (coroutine-function calls excluded from fusion, deopt strategy for YIELD/RESUME)

✅ Comprehensive test coverage covering root-frame yield, function-local yield/resume, completion tracking, error handling, and nested coroutines across both threaded and JIT modes

✅ Excellent documentation in code:

• docs/architecture.md explains the design in detail
• docs/instruction-set.md documents the four new opcodes clearly
• docs/jit-internals.md explains the suspend/deopt/resume strategy
• Roadmap updated

✅ CI passing (ubuntu + WIP checks green)

✅ Proper code organization — implementation split across coroutine.go, threaded.go, jit_arm64.go, fuse.go, and trace.go as appropriate

Test & Coverage Notes

Core functionality: ✅ Pass — root yield, coroutine calls, resume, completion detection all tested

Code coverage: 78.21% of changes

• interp/fuse.go (28.57%): early return paths for skipping fusion on coroutine-functions
• interp/threaded.go (78.66%): likely ARM64 JIT paths not fully exercised
• interp/coroutine.go (90%): minor Refs() edge cases

While coverage could be better, the untested lines are mostly optimization and JIT-specific paths; core functionality is well-tested.

Readiness Checklist

Path to Merge

1. Update the PR description (see blocking finding chore: Configure Renovate #1)
2. Optionally link to the related issue/spec (see blocking finding chore(deps): update dependency go to v1.25.2 #2)
3. Ready to merge

The code is solid. Once the PR metadata is complete, this is ready.

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