check-impl-against-spec

# Check implementation against spec Use this skill only when `spec_context.md` exists during PR review. ## Goal Determine whether the implementation in the checked-out PR materially matches the approved spec context. This is a supplement to the normal code review, not a separate output. ## Inputs - `spec_context.md` contains the spec context to compare against. It may include both product spec content (intended behavior, acceptance criteria) and tech spec content (implementation details, file changes). - `pr_diff.txt` contains the annotated diff for the PR. - `pr_description.md` may contain additional scope or rationale. - The working tree contains the PR branch contents. ## Process 1. Read `spec_context.md` and extract the concrete commitments it makes: - required behaviors (from the product spec) - required files or subsystems to change (from the tech spec) - stated constraints - required follow-up steps, validation, or migrations 2. Compare those commitments against the actual implementation in `pr_diff.txt` and the checked-out files. 3. Treat small implementation-level adjustments as acceptable when they preserve the spec's intent. Do not flag harmless differences in naming, structure, or low-level technique. 4. Flag a mismatch only when it is material, such as: - required behavior in the product spec is missing - the implementation contradicts a spec decision - the change introduces significant unplanned scope - a required validation, migration, or compatibility step from the tech spec is absent ## Outputs - Do not create a separate report file. - Fold spec-alignment findings into `review.json`. - Put broad spec-drift concerns in the review summary. - Add inline comments only when the mismatch can be tied to changed lines in the diff. - Treat material spec drift as at least an important concern. - If the implementation matches the spec closely enough, do not add comments just to mention alignment. ## Boundaries - Do not require literal one-to-one implementation of the spec when the PR achieves the same outcome safely. - Do not speculate about spec details that are not actually present in `spec_context.md`. - Do not post to GitHub directly.