fips/CONTRIBUTING.md

Contributing to FIPS

FIPS is a mesh routing protocol for Nostr identities over arbitrary transports. The architecture is layered, top to bottom:

• IPv6 TUN compatibility layer — presents the mesh as a local network interface (fips0) so unmodified applications can use it. Applications send IPv6 packets to fd::/8 addresses derived from Nostr pubkeys; the daemon converts between IPv6 packets and FSP datagrams.
• FSP (FIPS Session Protocol) — end-to-end encrypted sessions between identities, with periodic rekey.
• FMP (FIPS Mesh Protocol) — peer management, spanning tree, bloom filters, routing and forwarding, and link encryption.
• Transport — the actual wire: UDP, TCP, Tor, Bluetooth LE, Ethernet, and so on. Each transport plugs into FMP via a trait.

Most non-trivial changes affect behavior visible across the mesh — how nodes find each other, how packets route, how sessions rekey, how peers recover from failure. A single-node cargo test run is necessary but not sufficient for that class of change; the integration harness in testing/ is where regressions actually surface. This document covers the workflow assuming that context. Protocol depth lives in docs/design/.

Quick start

git clone https://github.com/jmcorgan/fips.git
cd fips
cargo build
cargo test

The pinned toolchain in rust-toolchain.toml is used for deterministic builds. On Linux, a source build requires libclang (sudo apt install libclang-dev on Debian/Ubuntu): the LAN gateway's nftables bindings are generated by bindgen at build time and fail without it. BLE-capable builds additionally need bluez, libdbus-1-dev, and pkg-config installed; the default build picks up BLE if those are present and skips it cleanly if not.

On Nix, nix develop provides the pinned toolchain and all of these build prerequisites without any manual install; see the Nix / NixOS section of packaging/README.md.

For multi-node integration runs, Docker is required. The harness under testing/ starts containerized topologies and exercises real mesh behavior; see testing/README.md for the suite catalog.

For a guided first-run that joins the public test mesh, see docs/tutorials/join-the-test-mesh.md. Pointing your local daemon at a test-* node is the cheapest way to dogfood a change end-to-end before opening a PR.

Choosing a branch to target

FIPS uses three long-lived branches, each a superset of the previous:

• maint — bug fixes for the latest released version.
• master — compatible work for the next feature release.
• next — wire-format-breaking and API-breaking work, staged for the next forklift release.

Pick the branch that matches the scope of your change:

Your change	Target
Bug fix in a feature that shipped in the latest release	maint
Bug fix in code added on master since the last release	master
Bug fix in next-only code (wire-format-breaking work)	next
New feature, no wire-format or API break	master
Wire-format-breaking or API-breaking change	next
Documentation, CI, contributor-facing changes	maint if they apply to released material, else master

When in doubt, ask in the issue. The maintainer can retarget if needed. The full release workflow, version conventions, and merge-direction rationale are in docs/branching.md.

Reporting bugs

Search open issues before filing a new one — duplicates are common in a young project.

When you open a bug report, please include:

• FIPS version (fipsctl --version)
• Rust toolchain version (rustc --version)
• OS / distro (Linux distro + kernel, or macOS / Windows version)
• What you expected to happen — your mental model of the behavior, ideally referencing the relevant docs or config field.
• What actually happened — the observed behavior, including the surprise.
• Reproduction steps — minimal and deterministic if you can. Multi-node bugs should include the topology and per-node config excerpts.
• Evidence — relevant log excerpts (journalctl -u fips or stdout with RUST_LOG=info or debug), fipsctl show output if relevant (peers, links, status), and any visible mesh state.

One issue per bug. Don't bundle unrelated symptoms even if you suspect they share a root cause — the maintainer will link them if they turn out to be related.

Submitting pull requests

Scope discipline

Every PR should make one logical change. The reviewer should be able to read the whole diff and trace every line back to the PR's stated purpose.

• No drive-by reformatting of unrelated files.
• No unrelated refactors folded into a bug fix or a feature PR.
• No "while I was in there" cleanups in files outside the change's natural footprint. Send them as separate PRs; they'll usually land faster on their own.
• Pre-existing lint warnings in files you didn't touch are not yours to fix in this PR.

Required before opening any PR

Run these locally and confirm they all pass:

cargo fmt --check
cargo build
cargo clippy --all-targets -- -D warnings
cargo test

fmt and clippy -D warnings are CI gates — PRs with formatting drift or new clippy warnings will fail CI and be sent back.

Then run the integration suite that exercises your change:

./testing/ci-local.sh --only <suite>

See testing/README.md for the available suites and what each covers. Routing, discovery, rekey, NAT, gateway, and transport changes all have specific suites; pick the narrowest one that touches your code path.

Recommended before opening: the full local CI run.

./testing/ci-local.sh

This is the same matrix that runs on GitHub Actions. Catching a regression locally is much cheaper than catching it in CI.

Self-review against the project review checklist

The 13-criteria checklist the maintainer runs on every incoming PR is published at PR-REVIEW.md. Run your own change through it before opening — or hand the document to your coding agent with "review my branch against this checklist" and let it do the pass. The checklist covers PR hygiene (body, commit shape, base freshness), diff content (does the change do what the description says, does it fit the codebase as a natural extension), and cross-cutting concerns (tests, docs, dependencies, security, contributor-conventional Rust patterns).

This is the first thing the maintainer does on any submission, so running it yourself saves a review round trip.

Additional requirements for feature PRs

• New CI coverage. Features added without a test that exercises them won't be reviewed. Either extend an existing integration suite or add a new one under testing/. Coverage of just the happy path is fine for an initial PR; edge cases can land as follow-ups.
• Documentation updated alongside the code. Protocol changes update the relevant docs/design/ page. Config changes update the operator-facing docs in docs/ and the reference config. Behavior visible to operators updates README.md and any tutorial it touches.

Additional requirements for bug-fix PRs

• A regression test where practical. If a regression test isn't tractable (some bugs only surface under timing or scale that's hard to encode), say so in the PR description with a one-paragraph explanation.
• Commit message references the bug: the symptom, the root cause in one sentence, and the fix shape.

Merge mechanics

PRs are merged via squash-merge. One logical change per PR becomes one commit on the destination branch, which keeps git bisect useful across the integration suite. Your in-PR commit history doesn't matter for the final landed history — the maintainer rewrites the commit message at merge time.

AI coding assistant policy

Use of AI coding assistants (Claude Code, Copilot, Cursor, Aider, and similar) in preparing a contribution is welcome. These tools are force multipliers and we have no objection in principle to their use in writing code, tests, documentation, or PR descriptions.

What we require is that the contributor does a thorough manual review and editorial pass over the output before submission. Concretely:

• Verify that the code does what it claims, not just that it compiles.
• Verify that any tests the agent wrote actually test something useful, not just that they pass.
• Verify that any documentation matches the behavior.
• Spot-check the diff for nothing-surprising: no unrelated files modified, no fabricated APIs, no references to symbols that don't exist, no version bumps you didn't intend, no churn outside the change's natural footprint.
• Be ready to discuss the design choices in the PR as if you wrote every line, because for the purposes of accountability you did.

The coding agent is a tool. The contributor is the author of record and is accountable for whatever they submit. PRs are reviewed on what they contain, not on who or what wrote them.

Review effort scales with submission effort. A submission that shows signs of being unreviewed agent output — irrelevant edits scattered across the tree, hallucinated function names, mismatched test/behavior pairs, fabricated API references, ChatGPT-style summary prose in comments — will receive an AI-coding-agent reply in turn, without human review. If you want a human reviewer's attention, do the editorial pass yourself first.

Repeated submissions of unreviewed AI output will result in the contributor being asked to step back and may result in account restrictions.

Where the conversation happens

• GitHub issues — bugs, feature requests, design discussions that don't fit on a specific PR.
• GitHub PRs — design discussion specific to a change in flight. Comment threads on the diff are the right place to push back on a decision.
• fips.network — community page, podcast, and the project's Nostr account. Broader project conversation and announcements happen here.

For implementation questions specific to your PR, ask in the PR itself. For design or roadmap questions that don't have a clear PR home yet, file a GitHub issue with the design label.

Further reading

• PR-REVIEW.md — the 13-criteria PR review checklist the maintainer runs on every incoming PR; run it yourself before opening to save a round trip.
• docs/design/README.md — protocol design tree.
• docs/branching.md — full release workflow and merge-direction rationale.
• docs/getting-started.md — operator walkthrough for a new node.
• docs/tutorials/join-the-test-mesh.md — how to dogfood your change against the public test mesh.
• testing/README.md — integration suite catalog.