/change-review

name: change-review
description: >
  Use when reviewing a set of changes before they merge — a PR, a branch diff, or the working-tree
  changes you just made — in a Repowise-indexed codebase (.repowise/ directory exists). Activates
  for "review this PR", "is this safe to merge", "what's the blast radius of these changes", "did I
  miss anything", or "what else should change with this".
user-invocable: false

Change Review with Repowise

When a diff is on the table, Repowise turns "what files changed" into "what does this change put at risk" — fusing git history (churn, ownership, co-change) with graph topology (dependents, impact surface), test gaps, security signals, and the architectural decisions that govern the touched code.

Two complementary risk signals, use both:

• **`get_change_risk(revspec=…)` (MCP)** scores the *whole change as one unit* (a

commit or a `base..head` range) from its diff shape: a single 0-10 defect-risk score with drivers (lines added/deleted, files, directories, subsystems, change entropy, author familiarity). No LLM, no network. Prefer this in-MCP tool; it takes a revspec and diffs server-side, so you never shell out. Lead with `risk_percentile` (this change ranked against sampled recent commits), summarized by `review_priority` and `classification`; `score` / `level` are the corpus-calibrated fallback. This is the pre-merge gate: "how risky is this change overall?" The `repowise risk <revspec>` CLI is the identical scorer for when you are already in a terminal.

• **`get_risk(changed_files=…)` (MCP)** works *per file* and returns the

`directive` block, the specific things to check inside the diff.

Score the whole change first

get_change_risk(revspec="main..HEAD")   # HEAD, a commit SHA, or base..head

Read `risk_percentile` and the top drivers: a high score from large diffusion (many dirs/subsystems) or low author familiarity tells you where to look hardest. `extensions=[".py", ".ts"]` counts only certain file types; `exclude_patterns=["tests/"]` omits paths. A `warning` field means the revspec or filters matched no files, so an all-zero score there is not a clean bill of health. The equivalent from a terminal is `repowise risk <revspec>` (add `--ext .py,.ts` or `--format json`).

Then drill into the directive block

Call `get_risk` in **PR mode** by passing the changed files:

get_risk(targets=<changed files>, changed_files=<same changed files>)

The response carries a `directive` block — read it first, it's a few short lists:

• **`will_break`** — files/symbols that depend on what changed but are *not* in

the diff. These are the likely breakages. Check each one.

• **`missing_cochanges`** — files that historically change together with the

changed files but were left untouched. Often a forgotten update.

• **`missing_tests`** — changed code with a test gap. Flag for new/updated tests.
• **`tests_to_run`** — the positive complement of `missing_tests`: the tests the

per-test coverage map proves execute the changed files (pytest-runnable ids). Recommend running these to validate the change. Empty until a coverage map is ingested (`repowise coverage add`); empty is "unknown", never "no tests exist".

`pr_blast_radius` holds the fuller dossier behind those lists (including the per-changed-file `guarding_tests` breakdown behind `tests_to_run`).

For the line-precise version from a terminal, `repowise impacted-tests <revspec>` maps each changed line to the tests whose recorded coverage touches it, then prints the ids (`--format list | xargs pytest` runs exactly them). It is honest about gaps: a changed file with no coverage rows is a labelled filename guess, and a brand-new file is "unknown, run the full suite", never "no tests needed".

Then go deeper where it matters

1. **Why does this code exist?** For any non-trivial changed file, call `get_why(query="<file>")` — don't let a change silently contradict a recorded architectural decision. Surface `conflicts_with` / `supersedes` hits. 2. **Did the change make health worse?** `get_health(targets=<changed files>, include=["biomarkers"])` — call out new complexity, deep nesting, or duplication the diff introduced. 3. **Who should review?** `get_risk` ownership + co-change signals suggest the people with the most context on the touched code.

Getting the diff

• A GitHub PR: `gh pr diff <number>` (or `gh pr view <number> --json files`).
• A branch: `git diff --name-only main...HEAD`.
• Working tree: `git status --porcelain`.
• CLI shortcut for a range: `repowise risk main..HEAD` scores a branch/PR range

for defect risk directly.

Write the review around evidence

Lead with a risk level and the `directive` findings, each tied to a concrete file. Distinguish **"will break"** (a dependent outside the diff) from **"worth a look"** (a co-change or health regression). Don't pad with findings the tools didn't support.

Error handling

If `get_risk` errors or returns nothing, the MCP server may be down or the repo unindexed — say so and review from the raw diff, noting that Repowise context was unavailable. Suggest `/repowise:init` if the repo isn't indexed.