diffing-pr-read

name	diffing-pr-read
description	Read a GitHub pull request through diffing with token-efficient bounded inspect APIs instead of dumping gh pr view/diff or the full patch. Use when summarizing a PR, inspecting PR changes, preparing a review, or reading PR discussion with minimal context.

Read a GitHub PR through diffing (token-efficient)

Prefer diffing’s slim PR overview and bounded diff inspect over gh pr view, gh pr diff, or GET /api/diff full patches.

Setup

1. Target the correct repository. List diffing sessions --json when a shell is available; reuse a gh-pr entry only when its scope matches the requested PR.
2. Select the match with diffing sessions use <id>. If none exists, start diffing --gh-pr <ref> --no-open (or diffing "gh pr <ref>" --no-open); it coexists with local and other PR reviews and becomes active.
3. Attach or reconnect MCP after selection, call review_session_status, then confirm normalized PR identity with gh_overview. start_review_session is for local web diffs and must not be used for PR mode.
4. Do not replace or stop another session just to read this PR. If the shell/session manager is unavailable and MCP is pinned to a different session, report that selection is required rather than reading the wrong PR.

<ref> may be a number, owner/repo#N, or a full PR URL.

Token-efficient read ladder

Never load the full patch or full session JSON by default.

Step	MCP	CLI
Identity + counts	gh_overview	diffing gh overview [--json]
Patch totals	diff_summary	diffing inspect summary
File list	diff_files (page nextCursor)	diffing inspect files --cursor N --limit 50
Hunk map	diff_hunks	diffing inspect hunks --file N --generation G
Body rows	diff_slice	diffing inspect slice --file N --start R --max-lines 120 --generation G
Find text	diff_search	diffing inspect search "literal" --generation G
Discussion	gh_list_threads (unresolvedOnly)	diffing gh threads --unresolved
Verdicts	gh_list_reviews	diffing gh reviews

Rules

• Carry generation from diff_summary into hunks/slice/search. On stale generation (HTTP 409), re-run summary and restart that file’s traversal.
• Consume MCP structuredContent and returned cursors directly. Do not call review_session_status, gh_overview, or the same page repeatedly when nothing changed.
• Keep default or smaller line/byte budgets; raise only when necessary.
• Continue slices with nextRow and file lists with nextCursor. Continue search with nextFile + nextRow.
• Prefer gh_list_threads with unresolvedOnly: true and truncated bodies. Use fullBody / --full-body only for threads you will act on.
• Compact JSON is default. Avoid --pretty and avoid GET /api/gh/session (fat UI payload).
• get_diff / full GET /api/diff is an escape hatch only when inspect is unavailable.

Optional: leave review findings

This skill is read-first. To post draft review comments on the PR session, follow diffing-review (PR section): create drafts via gh_create_draft_comment / POST /api/gh/pr-session/comments, then publish only with explicit user authorization (gh_submit_review dry-run first).

CLI sketch

diffing sessions --json
diffing sessions use <matching-pr-session-id>  # reuse when present
# Or, when none matches:
diffing --gh-pr 1234 --no-open                  # starts a concurrent active session
diffing gh overview --json
diffing inspect summary
diffing inspect files --limit 50
diffing inspect hunks --file 0 --generation <g>
diffing inspect slice --file 0 --start 0 --max-lines 120 --generation <g>
diffing gh threads --unresolved          # XML default
diffing gh reviews --format json

Anti-patterns

• Dumping gh pr diff or the entire unified patch into context.
• Calling GET /api/gh/session for “status” when gh overview exists.
• Loading every resolved historical thread body when only unresolved feedback matters.
• Starting a duplicate PR session when a compatible one can be selected by ID.