oss-contribute

name	oss-contribute
description	Use this skill when the user wants to contribute to an open-source GitHub repository — finding good first issues, claiming an issue, opening a pull request that matches the project's contributor guide, running the project's own verification stack locally, and shepherding the PR through CI and review. Trigger on phrases like "contribute to <repo>", "open source contribution", "find good first issues in <repo>", "open a PR for issue
license	Complete terms in LICENSE.txt

Open-Source Contribution Workflow

Overview

This skill walks Claude through the full lifecycle of landing a pull request in any GitHub-hosted open-source repository: discovering a tractable issue, deeply understanding the target codebase, designing the change, implementing it under the project's own verification stack, opening a maintainer-friendly PR, and watching it through CI.

This skill does not invent conventions. Every formatting, linting, testing, commit-message, and PR-description rule is read out of the target repo (AGENTS.md / CLAUDE.md / CONTRIBUTING.md / Makefile / .github/workflows/ / .github/PULL_REQUEST_TEMPLATE/). When the target repo is silent on a rule, fall back to the language-default in references/verification-stacks.md.

Quality bar. A PR landed via this skill should be indistinguishable from one written by a careful human contributor: small blast radius, tests covering the new behavior, clean against the project's own lint/type/test commands, a PR description that fills the project's template, and zero references to AI tooling in the PR body or commit messages unless the user explicitly asks for attribution.

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Process

The workflow is eight phases. Pause for explicit user confirmation before any action that pushes code, opens a PR, or posts a public comment. A list of every confirm-before-acting checkpoint is at the bottom under "Confirmation gates."

Phase 1 — Repo recon

Before reading any issue, learn the project's rules. See references/repo-recon-checklist.md for the full list.

Read in this order. Use mcp__github__get_file_contents for read-only repo browsing; fall back to gh api repos/<owner>/<repo>/contents/<path> if the MCP server is unavailable.

1. AGENTS.md (root) — modern contributor charters live here. May supersede CONTRIBUTING.md.
2. CLAUDE.md (root) — usually points at AGENTS.md but may add Claude-specific rules.
3. CONTRIBUTING.md (root or .github/).
4. README.md — for stack and quickstart.
5. Makefile / pyproject.toml / package.json / go.mod / Cargo.toml — to identify the verification stack.
6. .github/workflows/*.yml — to enumerate CI checks that block merge. Note which jobs are Required.
7. .github/PULL_REQUEST_TEMPLATE/ (or .github/pull_request_template.md) — for the body shape.
8. .github/ISSUE_TEMPLATE/ — useful for understanding how issues are labeled and categorized.

Extract a one-page recon brief (in your own working memory, not as a file) covering:

• Verification stack: exact commands to run locally before committing.
• Code style: line length, comment style (full sentences? imperative?), import order.
• Public-API rules: positional-compatibility, deprecation policy.
• Commit / branch naming: e.g. feat/<short> vs feat/<issue#>-<short>.
• PR template sections: what every section must contain.
• Known landmines: "coordinated updates across N files when adding X" rules.

If AGENTS.md says to use a specific skill (e.g. $code-change-verification), invoke that skill in Phase 6 — don't override its commands with our defaults.

Phase 2 — Issue triage

Goal: surface 3–5 candidate issues ranked by mergeability for a first-time contributor.

gh issue list -R <owner>/<repo> --state open --limit 100

Or via MCP: mcp__github__list_issues with state: OPEN, orderBy: CREATED_AT, direction: DESC, perPage: 50.

If the response is too large for the context window, the tool will save it to disk and return a path. Delegate parsing to a subagent with explicit instructions to slice the file in 80k-character spans and return a structured table with number / title / labels / comment_count / created / one-line summary. Do not try to read a 70k+ character JSON blob inline.

Score each issue with the rubric in references/issue-scoring-rubric.md. Six axes: blast radius, scope clarity, controversy, prior-art status, contributor-guide alignment, age. Present the top 5 in a table:

| # | Title | Why it ranks | Watchouts |
|---|-------|--------------|-----------|

Wait for the user to pick. Do not advance past this gate without an explicit pick.

Phase 3 — Deep read of the chosen issue

Once the user picks issue #N:

1. Read mcp__github__issue_read get for the body.
2. Read mcp__github__issue_read get_comments for the discussion.
3. Read mcp__github__issue_read get_sub_issues if the issue tracker uses sub-issues.
4. Search for prior-art PRs:
   • gh pr list -R <owner>/<repo> --search "is:pr #N"
   • gh pr list -R <owner>/<repo> --search "<verbatim title fragment>"
   • Scan recent merged PRs touching the same files.
5. If a prior PR exists, read its diff and check_runs. Determine: is it stale? does it have tests? is it dirty? Decide whether to defer, supersede with explicit acknowledgment, or differentiate the scope.

If the issue is already actively being worked (a non-stale PR exists, or a recent comment from someone saying "I'll work on this") — surface this to the user and pause. Do not proceed without explicit go-ahead.

Phase 4 — Tree-of-thoughts implementation design

Never jump to the easiest patch without considering alternatives.

Present 2–4 implementation shapes in a comparison table:

| Shape | Scope | Merge probability | Verdict |
|-------|-------|-------------------|---------|
| A. Minimal …    | … | … | reject/chosen |
| B. With tests … | … | … | … |
| C. + Refactor … | … | … | … |
| D. Full scope … | … | … | … |

Each row needs a one-line "why" for its merge-probability score. Pick one with a short justification.

Write a concise plan to a working memory location (do not write it into the target repo). Include:

• Files to modify (with line-number anchors if known).
• Functions/utilities to reuse from the existing codebase.
• Tests to add (count, names, coverage matrix).
• Out of scope items, with explicit reasoning.
• Risks with mitigations.

Confirmation gate: show the user the plan and the chosen shape. Wait for confirmation before any code edits. If the user picks a different shape, regenerate the plan and confirm again.

Phase 5 — Setup (idempotent)

All steps are idempotent. Detect existing artifacts and reuse rather than recreating.

Fork

gh auth status                                            # confirm authenticated as user
gh repo view <user>/<repo> >/dev/null 2>&1 \
  || gh repo fork <owner>/<repo> --clone=false            # fork only if missing

Some MCP GitHub tokens lack repo scope and will 403 on mcp__github__fork_repository. If that happens, run the gh CLI fallback. If gh isn't authenticated, see references/troubleshooting.md for the device-flow login.

Local clone

CLONE_DIR="${OSS_HOME:-$HOME/oss}/<repo>"
[ -d "$CLONE_DIR/.git" ] \
  || gh repo clone <user>/<repo> "$CLONE_DIR"
cd "$CLONE_DIR"

On Windows, default to D:/open-source/<repo> if D: exists, else ~/oss/<repo>.

Upstream remote and main sync

git remote get-url upstream >/dev/null 2>&1 \
  || git remote add upstream https://github.com/<owner>/<repo>.git
git fetch upstream main 2>&1 | tail -3
git checkout main
git merge upstream/main --ff-only

If main is the wrong default branch, detect via gh repo view <owner>/<repo> --json defaultBranchRef --jq .defaultBranchRef.name.

Feature branch

Branch naming follows the contributor guide. Default if not specified: feat/<issue#>-<short-kebab> for features, fix/<issue#>-<short-kebab> for bugs, docs/<issue#>-<short-kebab> for docs.

BRANCH="feat/<N>-<short>"
git show-ref --quiet "refs/heads/$BRANCH" \
  && git checkout "$BRANCH" \
  || git checkout -b "$BRANCH"

If the branch already exists with unrelated commits, ask the user before resetting it. Do not silently clobber prior work.

Defensive git auth setup

gh auth setup-git

Run this once before any push. It overrides Windows Credential Manager's stale credentials, which is the #1 cause of mysterious 403s on push.

Phase 6 — Implement

Apply edits

Use the Edit tool for surgical changes; Write only for new files. Preserve existing indentation and comment style. Do not reformat unrelated lines.

Style rules to internalize from Phase 1's recon brief:

• Comments as full sentences ending with periods (if the project enforces this).
• Imports kept sorted by the project's tool (isort, ruff, eslint --fix).
• Public APIs: respect positional-argument compatibility — append new params, never insert.
• Docstrings: match the project's existing style (Google / NumPy / one-liner / etc.).

Run the verification stack

Use the exact commands from the project's contributor guide. If absent, route through the cookbook in references/verification-stacks.md. Run in this order; do not skip steps:

1. Format (make format / uv run ruff format / pnpm format / cargo fmt / gofmt -w).
2. Lint (make lint / ruff check / pnpm lint / cargo clippy / go vet).
3. Typecheck (make typecheck / mypy + pyright / tsc --noEmit / N/A for Go/Rust beyond compile).
4. Tests (make tests / pytest / pnpm test / cargo test / go test ./...).

Do not run the test suite in parallel with the format/lint stages on the first pass — failures cascade and obscure root causes.

Diagnose failing tests

If a test fails, run it in isolation with -v to see the full traceback. Before assuming the failure is yours:

git stash
<re-run the same test command>          # fail or pass on clean main?
git stash pop
git checkout <auto-modified files>      # discard lockfile/uv.lock noise

If the test fails on clean main too, it is not your bug — note it in the PR description's "Test plan" section as a pre-existing failure unrelated to this change. Do not try to fix it.

Type-narrowing footguns

Common type-checker complaints in this exact pattern:

• mypy: Incompatible return value type (got "object | Any", expected "str | None") on TypedDict union narrowing → wrap with cast(str | None, ...) or str(x) if x is not None else None.
• mypy: dict[str, V].get() on a heterogeneous TypedDict union returns object → same fix.
• pyright: complaint on Any | None when union has Pydantic models → use getattr(obj, "x", None) not direct attribute access.

See references/troubleshooting.md for the full list.

Lockfile noise

uv sync, pnpm install, cargo update, go mod tidy may rewrite lockfiles even when no semantic change is needed. After verification, run git status and git checkout <lockfile> if the diff is unrelated to the change. Never commit lockfile churn unrelated to the actual change.

Phase 7 — Commit, push, open PR

Commit

Match the project's commit-message convention (Conventional Commits, 50/72, custom). Default to:

<type>(<scope>): <short imperative summary>

<body explaining the why, wrapped at 72>

Closes #<N>

If the repo requires DCO sign-off (look for dco.yml workflow or Signed-off-by in recent commits): use git commit -s.

Confirmation gate: show the user the diff (git diff --stat + git diff) and the proposed commit message. Wait for explicit OK before committing.

Push

gh auth setup-git                                     # defensive, no-op if already set
git push -u origin "$BRANCH"

If push 403s with "denied to ", that's stale Windows credentials despite setup-git. See references/troubleshooting.md.

Confirmation gate: confirm with the user before pushing.

Open the PR

Use gh pr create -R <owner>/<repo>. Body fills the project's template (read from Phase 1).

Default body shape — adapt to the project's actual template:

### Summary

<2–4 sentences: gap, fix, scope.>

### Test plan

<Bullet list of verification commands that passed and the new tests added.>

### Issue number

Closes #<N>

### Notes

<Optional: prior PR acknowledgment, known limitations, follow-up issues.>

### Checks

- [x] I've added new tests (if relevant)
- [x] I've added/updated the relevant documentation
- [x] I've run `make lint` and `make format`
- [x] I've made sure tests pass

Tick checks truthfully. If you didn't add tests, leave the box unchecked and say so.

Default flags:

• --maintainer-can-modify so reviewers can rebase without ping-pong.
• No --draft unless there's a real reason; ready for review beats draft for landing speed.
• --base <default-branch> (read in Phase 5).
• --head <fork-user>:<branch>.

Confirmation gate: show the user the rendered title and body. Wait for explicit OK before opening.

See references/pr-description-template.md for three real-world examples (small bug fix / feature add / docs change).

Phase 8 — Watch CI and review

Start a Monitor task on the PR's check runs:

prev=""; while :; do
  raw=$(gh pr checks <N> -R <owner>/<repo> --json name,bucket,state 2>/dev/null || echo "[]")
  cur=$(echo "$raw" | jq -r '.[] | select(.bucket!="pending") | "\(.name): \(.bucket)"' | sort)
  diff <(echo "$prev") <(echo "$cur") | grep --line-buffered "^>" | sed 's/^> //'
  prev="$cur"
  pending=$(echo "$raw" | jq -r '.[] | select(.bucket=="pending") | .name' | wc -l)
  [ "$pending" -eq 0 ] && [ -n "$cur" ] && { echo "===ALL_DONE==="; echo "$cur"; break; }
  sleep 25
done

First-time-contributor gate

If the PR shows a yellow 1 workflow awaiting approval banner with checks in Expected — Waiting for status to be reported, this is GitHub's safety gate for new external contributors. No action needed from us — a maintainer must click "Approve and run workflows." Surface this calmly to the user; do not escalate.

CI failure

If a check fails:

1. Read the failure with gh run view <run-id> --log-failed.
2. Reproduce locally.
3. Fix.
4. Push to the same branch (the open PR auto-updates; no need to open a new one).
5. Wait for CI to re-run.

Reviewer feedback

If a reviewer requests changes:

1. Read every comment carefully — push back politely on requests that violate your understanding of the issue, but default to deferring to maintainers on style.
2. Address each comment in a separate commit when feasible (helps reviewers re-read).
3. Reply to the review thread with a one-liner pointing to the commit that addressed the comment.
4. After all comments addressed, request re-review via the PR UI.

Don't open another PR

While this PR is gated, in review, or has unresolved comments — do not open another PR to the same repo. Two open PRs from a fresh contributor look like contribution spam and dilute reviewer attention.

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Confirmation gates (mandatory pauses)

Before any of the following actions, pause and ask the user explicitly:

1. Picking an issue (Phase 2 → wait for user pick).
2. Implementation shape (Phase 4 → wait for OK on the chosen branch).
3. Plan acceptance (Phase 4 → wait for OK on the plan file content).
4. Commit (Phase 7 → show diff + message, wait for OK).
5. Push (Phase 7 → wait for OK).
6. PR creation (Phase 7 → show rendered title + body, wait for OK).
7. Comments on the issue or PR by us (any phase → wait for OK on the exact comment text).
8. Force-push, branch reset, or destructive git ops (any phase → wait for OK).

Skip a confirmation gate only if the user has explicitly granted blanket approval for the rest of this session ("just go").

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Anti-patterns

See references/anti-patterns.md for the full list with reasoning. Brief version:

• Don't open multiple PRs while the first is gated.
• Don't bikeshed-refactor surrounding code in the same PR.
• Don't --amend after pushing — push a new commit.
• Don't # noqa / # type: ignore to silence checker errors unless the project itself uses that escape hatch.
• Don't add a CHANGELOG entry unless the contributor guide says to.
• Don't write "tests added" in the PR Test plan; list the test names.
• Don't promise verification you didn't run.
• Don't reference Claude or AI assistance in the PR body or commits unless the user explicitly opts in.

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Output formats

Issue scoring table (Phase 2 output)

| # | Title (truncated) | Score | Why | Watchouts |
|---|---|---|---|---|
| 2886 | Add convenience properties to ToolCallItem | 9/10 | Additive, reference PR exists, tight scope | PR #2887 stale draft — supersede with note |

Implementation-shape comparison table (Phase 4 output)

| Shape | Scope (files / lines) | Merge probability | Verdict |
|-------|----------------------|-------------------|---------|
| A. Code only | items.py, ~22 lines | low — no value-add over existing draft | reject |
| **B. Code + tests** | items.py + test file, ~125 lines | **high — clear improvement** | **chosen** |

Plan summary message (Phase 4 → user)

Picked Shape B — adds tool_name / call_id properties on ToolCallItem (lines 362–376 of src/agents/items.py) plus 8 unit tests in tests/test_items_helpers.py. Reuses the existing ToolApprovalItem._extract_call_id pattern. Out of scope: runner threading for ToolCallOutputItem.tool_name (issue defers this; AGENTS.md flags multi-file coordination cost).

Verification: make format && make lint && make typecheck && make tests. Expected new test count: 26 → 34.

Risks: a draft PR (#2887) already exists for this issue. Plan acknowledges it in our PR body and offers to defer.

Reply go to start coding, or push back with edits.

Final summary (after PR opens)

✅ PR opened: Branch: <branch> on <user>/<repo> Diff: , <+lines>/<-lines> Verification (all green locally): <commands> CI status: <queued / running / N approvals needed / first-time gate> Next step: <wait / address review / etc.>

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Skill memory

If the user has the auto-memory system enabled (i.e. MEMORY.md and feedback_*.md files exist under ~/.claude/projects/.../memory/), record:

• The user's preferred OSS contribution destination (e.g. always under D:/open-source/).
• Their GitHub handle.
• Any project-specific feedback they give during a contribution ("don't reference Claude in PR bodies for this org").

Do not store credentials, API keys, or anything sensitive.

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When to NOT use this skill

• The user is asking a general question about a library — use claude-code-guide or context7 instead.
• The user is debugging their own code, not contributing upstream.
• The target is a private repo with no PR workflow — just commit and push.
• The target is on GitLab / Codeberg / Gitea / Bitbucket — this skill is GitHub-specific in v1.
• The user wants to do something destructive (force-push to main, mass-close issues) — refuse and recommend a safer path.