review-pr

name	review-pr
description	Visualize a pull request on the Cartographer map — see which entities are affected, the blast radius, and the review path. Use when user says "review pr", "review pull request", or "/cartographer review-pr".
model	opus
effort	high
argument-hint	[PR number or branch name]

PR Review on Cartographer Map

Overlay a pull request onto the existing world-model so the user can spatially understand what the PR changes and what it affects.

Prerequisite: The codebase must already have a world-model. If cartographer_get_summary returns 0 entities, tell the user to run /cartographer analyze first.

Steps

1. Set project

Call cartographer_set_project with the project root path.

2. Get the PR diff

Use $ARGUMENTS as the PR identifier (number, branch name, or URL).

gh pr diff $ARGUMENTS --name-only

This gives you the list of changed files. If the user didn't provide a PR number, check if there's a current branch with an open PR:

gh pr view --json number,title,headRefName

3. Read the diff details

For each changed file (or the most important ones if there are many):

gh pr diff $ARGUMENTS

Understand what actually changed — not just which files, but what the changes DO.

4. Match changes to world-model entities

Call cartographer_query to find entities in the model. Match by:

• Entity names that correspond to changed functions/components
• Evidence anchors that reference the changed file paths
• Relationships involving changed entities

If a changed file doesn't match any entity in the model, note it — the model may need updating.

5. Determine review order

Order the affected entities from primary change to downstream impact:

1. Core change — the main entity the PR modifies (what the PR is "about")
2. Supporting changes — entities that changed to support the core
3. Affected consumers — entities that read/invoke the changed ones (blast radius)

6. Create the PR changeset

Use kind: "changeset" and changeType on each step so the map renders change-type indicators (green=added, amber=modified, red=removed, gray=affected).

cartographer_write_slice(
  name: "PR #123: Add auth middleware",
  description: "Adds authentication checks before write operations",
  kind: "changeset",
  steps: [
    { entityId: "capability:requireAuth", changeType: "added", label: "new auth middleware" },
    { entityId: "capability:registerTools", changeType: "modified", label: "added auth check before handler" },
    { entityId: "entity:WorldModelStore", changeType: "affected", label: "writes now require auth" },
    { entityId: "capability:broadcast", changeType: "affected", label: "receives only authed writes" }
  ],
  evidence: {
    anchors: [{ filePath: "...", lineStart: ..., lineEnd: ..., snippet: "..." }],
    confidence: "proven",
    provenance: "deterministic",
    reasoning: "Matched from git diff"
  }
)

Set changeType on each step:

• added — new entity introduced by the PR (green indicator)
• modified — existing entity changed (amber indicator)
• removed — entity deleted by the PR (red indicator, strikethrough)
• affected — not changed directly but connected to something that was (gray indicator)

7. Open the map

cartographer_open_map

Tell the user:

• The PR is now visible in the Flows panel on the map
• Click it to highlight the affected path
• Click any highlighted entity to see the evidence/diff
• Non-highlighted entities that are still visible show the blast radius context

8. Summarize

Give the user a brief summary:

• How many entities affected (directly changed vs downstream)
• Whether the change is localized or cross-cutting
• Any entities in the model that SHOULD be affected but aren't in the diff (possible gaps)
• Any changed files that DON'T match model entities (model may be stale)