Reviewing Compiler PRs

Full dimension definitions and CHECK rules live in the expert-reviewer agent.

When to Invoke

• PR touches src/Compiler/ — invoke the expert-reviewer agent
• PR touches src/FSharp.Core/ — focus on FSharp.Core Stability, API Surface, Backward Compat, XML Docs
• PR touches vsintegration/ or LanguageServer/ — focus on IDE Responsiveness, Concurrency, Memory
• PR touches tests/ only — quick check: baselines explained? Cross-TFM coverage? Tests actually assert?
• PR touches eng/ or build scripts — focus on Build Infrastructure, Cross-Platform

Dimension Selection

Files Changed	Focus Dimensions
Checking/, TypedTree/	Type System, Overload Resolution, Struct Awareness, Feature Gating
CodeGen/, AbstractIL/	IL Emission, Debug Experience, Test Coverage
Optimize/	Optimization Correctness, IL Emission, Test Coverage
SyntaxTree/, pars.fsy	Parser Integrity, Feature Gating, Typed Tree Discipline
TypedTreePickle.*, CompilerImports.*	Binary Compatibility (highest priority)
Service/	FCS API Surface, IDE Responsiveness, Concurrency, Incremental Checking
LanguageServer/	IDE Responsiveness, Concurrency
Driver/	Build Infrastructure, Incremental Checking, Cancellation
Facilities/	Feature Gating, Concurrency
FSComp.txt	Diagnostic Quality
FSharp.Core/	FSharp.Core Stability, Backward Compat, XML Docs, RFC Process
vsintegration/	IDE Responsiveness, Memory Footprint, Cross-Platform
eng/, setup/, build scripts	Build Infrastructure, Cross-Platform

Subagent Dispatch

For each selected dimension from the table above, the expert-reviewer agent MUST launch an independent subagent (background task) to assess that dimension. This is not optional — a single agent doing all dimensions sequentially produces shallow analysis and wall-of-text summaries.

Each subagent receives:

1. The dimension's CHECK rules (from expert-reviewer.md)
2. The relevant file diffs (filtered by the dimension's hotspot paths)
3. Instructions to produce a structured finding: {file, line, severity, dimension, issue, suggestion} or LGTM if no findings

The expert-reviewer consolidates subagent results, deduplicates, applies assessment gates, and posts as inline comments per Wave 5.

Assessment gates — apply before flagging:

• Understand execution context before judging (test harness ≠ compiler runtime)
• Classify as regression, improvement, or unclear — only regressions are findings
• Require a concrete failing scenario — no hypotheticals
• "Correct convention" for the context in use → discard, not a finding
• "Unexplained" ≠ "wrong" — missing rationale in a commit message is a doc gap, not a defect

Consolidation:

1. Deduplicate findings at same location
2. Filter: wrong context → discard; improvement → downgrade; speculation → LOW
3. Classify: Behavioral (correctness) → Quality (structure) → Nitpick (style)
4. Rank by cross-model agreement (≥2 models agree = higher confidence)
5. Present Behavioral first; Nitpicks only if nothing higher — agents love producing nitpicks to have something to say, deprioritize them

Self-Review Checklist

1. Every behavioral change has a test
2. FSharp.Core changes maintain binary compatibility
3. No unintended public API surface changes
4. New language features have a LanguageFeature guard and RFC
5. No raw TType_* matching without stripTyEqns
6. Cancellation tokens threaded through async operations
7. Cleanup changes separate from feature enablement

Full dimension CHECK rules are in the expert-reviewer agent.