Look at what is open first. Pull the whole list, drafts included: gh pr list -R tangency-labs/solidcraft --state open --limit 500 and gh issue list -R tangency-labs/solidcraft --state open --limit 500. Look for the same issue, the same feature under another number, and PRs that change the files you will change (gh pr list ... --json number,title,files). If someone has it, comment on their PR or issue instead of opening a second one: two PRs for one change cannot both land.
Claim with a draft PR. gh pr list -R tangency-labs/solidcraft --state open --search "#N"; if none, branch from the latest origin/main, git commit --allow-empty -m "claim: #N", push, and open a draft PR titled <summary> (#N). The lowest-numbered open PR for an issue wins; close yours if it lost. The bot assigns you and labels the issue in progress. Do not claim by editing files; comment /claim only to stake a claim before you have a branch.
Write the title and first sentence for a reader who has seen nothing else. Not your chat, not the issue, not the code. Maintainers pick what to review from the title, and it becomes the commit on main. Say which part of the app changes and what a user now sees or can do, in everyday words. Don't paste the issue's title unless it passes this too. Before opening the PR, and again before marking it ready, read both with everything else closed: if "there", "it", "this" or "that" has nothing to point at, or a term only makes sense after reading the diff, rewrite it. Keep the terms a user sees in the app and explain the others.
- Unclear: Send to Slicer: pick one print face per body there, and show print faces only while it is open
- Clear: 3D printing: choose the face each body rests on in the Send to Slicer window, not the face menu
Write PR text in plain, literal English. This follows the spirit of Simplified Technical English, not its approved-word list. Keep the names a user sees in the app, even if they aren't everyday words.
- One idea per sentence, and about 20 words at most.
- Use active voice: "The view tints the face", not "The face is tinted".
- Use one word for one thing, and don't switch to a synonym partway through.
- Repeat the noun when "it" or "this" could be unclear.
- Don't stack nouns: "the option for picking in the face menu", not "face menu picking option".
Push daily. A draft with no pushes for 72 hours may be taken over: comment first, then open your own claim (you may start from its branch). The bot's automatic cleanup deadlines in CONTRIBUTING.md are separate.
One topic and one issue per PR. Never commit plan/, build directories (target*/) or generated reference data; check git ls-files before pushing. Run cargo xtask ci before every commit. Commit after every feature arc that builds.
Merge flow. The heavy CI jobs start when a maintainer adds approved-for-ci; approved PRs go through the merge queue (gh pr merge N -R tangency-labs/solidcraft --squash --auto), which runs the full suite on each group before it lands on main. Never force-push main.
Do not push only to catch up with main (no merge of main, no Update branch, no rebase for that alone): every push restarts the whole CI run, and main's own run catches what lands in between. When you push anyway, or GitHub reports a conflict, rebase onto the latest main and push your own branch with --force-with-lease; never merge main into a PR. Resolve conflicts without discarding others' work. Do not re-run CI on an unchanged commit: re-run only a job that runner trouble cancelled, with "Re-run failed jobs".
Evidence. For observable CAD, UI or model behaviour (kernel, geometry, assembly and backend changes included), the issue or PR carries real screenshots or a short recording from a small reproduction, preferably before and after, with steps and expected/actual behaviour. Capture it yourself; do not ask a human for evidence you can produce. Diagrams do not replace it. Changes with nothing observable need none. Use a public-safe example, check for private designs, paths and account details, attach the media rather than committing it.
Follow through. Check the PR's merge status throughout and before handoff. Report the state you checked and any conflicts resolved. While the PR is open, keep monitoring it and say clearly that it is pending; do not claim it merged without checking.
Shared build machine. Check the load before a big build (cut -d' ' -f1 /proc/loadavg), wait while it is over 24, and build with nice.
Maintainers' machines keep a local, gitignored plan/ folder: read plan/STATUS.md (current milestone, next task), then the task in plan/execution-plan.md and the relevant plan/architecture.md section. Kernel and library decisions are in plan/adr/0001-geometry-kernel.md. Follow the autonomous operation protocol in plan/execution-plan.md section 6; do not stop to ask unless it lists the decision as the owner's. Contributors without plan/ can ignore this.
Update the roadmap when a milestone task lands: docs/roadmap-detail.md tracks status, milestones and estimates; ROADMAP.md is the short user-facing roadmap.
Start here. What to work on: ROADMAP.md, "Where help is wanted most" in CONTRIBUTING.md and the open issues labelled help wanted, good first issue, needs-triage; check what is already open first. Architecture: docs/architecture.md and "How the code is laid out" in CONTRIBUTING.md; kernel work is paused ("Kernel work is paused" in CONTRIBUTING.md). Licence rules: deny.toml and cargo xtask licences --check; only crates/kernel may use truck. When the code, docs and rules settle a question, act; ask on the issue or PR only when the answer changes what users see or what the change covers.
Do not open a second PR for an issue a lower-numbered open PR already closes, and keep the Changes a default: line filled in: pr-checks.yml fails both.
The gate reads the working tree. Do not switch branches while cargo xtask ci runs: it compiles the other branch's code and fails on a change not in the PR. Run it in the background and wait for its log.

1. Check the environment

Explain what you are checking and why, in everyday language. Run:

gh --version
gh auth status
git --version
rustup show
rustc --version
cargo --version
df -h .

Check available memory, CPU and whether a display is available. Establish whether this is the person's computer or a cloud sandbox; do not assume desktop access, persistent files or enough space for a full build. Compare Rust with the current minimum in CONTRIBUTING.md. If tools or sign-in are missing, explain the next step and help the person set them up; never ask them to paste credentials.

Before every public action, show the exact proposed content and destination and ask the person to approve it. This includes creating a public fork, pushing, opening or updating a PR, uploading evidence, marking it ready and commenting. Explain a PR as a request for maintainers to review a change. Keep check-ins short at each step: what you found, what comes next, and what needs their decision.

2. Fork and clone

Explain that changes go to their own copy on GitHub. After approval, run:

gh repo fork tangency-labs/solidcraft --clone --remote
cd solidcraft
git remote -v

Ensure origin points to the person's fork. If upstream is absent, add it:

git remote add upstream https://github.com/tangency-labs/solidcraft.git

Never push to upstream. If cloning an existing fork instead, check the same remote layout. With a clean working tree, sync local main before starting work:

git fetch upstream
git switch main
git merge --ff-only upstream/main

After approval, sync the fork with git push origin main. If fast-forwarding fails, inspect the divergence and preserve existing work; do not reset it away.

3. Choose an unclaimed task together

Ask about their interests and show a few issues that fit the available resources. Read the current kernel-pause notice in CONTRIBUTING.md and skip kernel work while paused, including tasks outside crates/kernel/ that change kernel behaviour. Fetch the whole open list, including drafts, before narrowing it:

gh issue list -R tangency-labs/solidcraft --state open --limit 500
gh pr list -R tangency-labs/solidcraft --state open --limit 500 --json number,title,files
gh issue list -R tangency-labs/solidcraft --state open --label 'good first issue' --search '-label:kernel-paused -label:"in progress"' --limit 100
gh issue list -R tangency-labs/solidcraft --state open --label 'help wanted' --search '-label:kernel-paused -label:"in progress"' --limit 100

Let the person choose. Set N to that issue's number, then inspect its discussion, assignee and linked PRs; check similar work under other numbers and overlapping files:

gh issue view "$N" -R tangency-labs/solidcraft --comments
gh pr list -R tangency-labs/solidcraft --state open --search "#$N"

If it is already claimed, choose another task with the person. Do not open a competing PR or post a comment without their approval.

4. Claim with a draft PR

Explain the proposed change and show the draft title and body for approval before publishing. Recheck availability immediately before claiming. Follow the claim rules in CONTRIBUTING.md; substitute the chosen summary and fork owner below:

git fetch upstream
git switch -c "fix-$N" upstream/main
git commit --allow-empty -m "claim: #$N"
git push -u origin "fix-$N"
gh pr create --repo tangency-labs/solidcraft --head "FORK_OWNER:fix-$N" --base main --draft --title "SUMMARY (#$N)" --body-file /tmp/solidcraft-pr-body.md

Write the body file first, describing the intended fix and referencing Fixes #N. The draft PR is the claim; check the bot's response and the lowest-numbered open PR rule before editing. If another claim won, explain it and ask before closing the duplicate. Do not try to claim by editing files.

5. Make and check one focused change

Explain the intended behaviour, then pick the skill for the area from AGENTS.md's table and follow it (never crash, commands, layering, clean-room rules and tests all live there). Put synthetic regression tests in the existing test module for the affected area; prove a bug test fails before the fix and passes after it.

Use the affected crate and test module in commands such as:

cargo test --profile ci -p solidcraft-engine --lib -- tests::feature_inputs_are_parameters
cargo clippy -p solidcraft-engine --all-targets -- -D warnings
cargo fmt --all -- --check
cargo xtask ci

Run cargo xtask ci before each implementation commit on a capable environment. On small environments, use targeted tests and report exactly what passed and what could not run; leave the full suite to CI rather than claiming it passed. Follow testing guidance for applicable checks. Review the diff, keep one topic, and commit the finished change. Before an approved push, follow "Rules for every PR" above; do not push solely to catch up with main. Explain progress and ask before publishing each update.

6. Show the result

For visible changes, reproduce the result with a small public-safe example and capture actual screenshots or a short recording, preferably before and after. For model output without a display, run:

solidcraft-cli snapshot script.json --out /tmp/solidcraft-result.png

For UI behaviour, launch the desktop app with a free control port:

cargo run --release -p solidcraft -- --sample --control 7878

Follow the control protocol: connect to 127.0.0.1:7878, read the launch token from its documented location, and send JSON lines. Put the real token in the first request's top-level token field:

{"id":1,"token":"TOKEN","method":"ui.inspect","params":{}}
{"id":2,"method":"ui.screenshot","params":{"path":"/tmp/solidcraft-result.png"}}

Use engine.execute for commands and ui.start plus ui.click for interactive reproductions. Open and inspect the image. Check for private designs, paths and credentials before sharing; never expose the token. Show the person the media and ask before attaching it to the PR or linking an accessible recording. Include brief reproduction steps and expected/actual behaviour; do not commit generated review media. Documentation-only changes need no screenshot.

7. Finish and respond to review

Prepare the final title and body: Fixes #N, the problem, resulting behaviour, validation and any evidence or limitations. Show them to the person before updating the PR. After their approval, mark the draft ready:

gh pr ready PR_NUMBER -R tangency-labs/solidcraft

Explain that a maintainer reviews the change and adds approved-for-ci to start heavy checks; do not add that label yourself. Monitor checks and merge status, address review comments, rerun affected checks for fixes, and ask before public replies or pushes. Report whether it merged or remains pending; do not promise a merge or rerun an unchanged failing check without evidence of infrastructure trouble.

Cloud sandbox

Without a display, use solidcraft-cli snapshot for model evidence or launch the app under Xvfb :99 with DISPLAY=:99 for UI evidence. With limited disk or CPU, prefer a documentation or small isolated task, targeted tests and existing build artifacts; explain any missing checks. Preserve work before temporary storage expires and ask before publishing it. Always push only to the person's fork, never to upstream.

solidcraft-contributing

Contribute to SolidCraft

Rules for every PR