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Contributing to Sprout
Welcome, and thank you for your interest in contributing! Sprout is an open-source project and we're glad you're here. This guide will help you get from zero to a merged pull request.
If you have questions that aren't answered here, open a GitHub Discussion or reach out in the community channels.
Table of Contents
- Code of Conduct
- Setting Up the Development Environment
- Running Tests
- Code Style
- Making a Pull Request
- Architecture Overview
- How to Add a New Event Kind
- How to Add a New MCP Tool
- How to Add a New API Endpoint
- License and CLA
Code of Conduct
This project follows the Contributor Covenant v2.1. By participating you agree to uphold these standards. Please report unacceptable behavior to conduct@sprout-relay.org.
Setting Up the Development Environment
Prerequisites
| Tool | Version | Notes |
|---|---|---|
| Rust | 1.88+ | Install via rustup |
| Node.js | 24+ | Required for desktop app commands and just ci |
| pnpm | 10+ | Required for desktop app commands and just ci |
| Docker | 24+ | For MySQL, Redis, Typesense |
just |
latest | Task runner — cargo install just |
lefthook |
latest | Optional; run lefthook install for local Git hooks |
sqlx-cli |
latest | Optional; just migrate falls back to docker exec |
This repo uses Hermit for toolchain pinning. Activate it once per shell session:
. ./bin/activate-hermit
Hermit pins Rust, just, and other tools to the versions in bin/. If you
don't use Hermit, make sure your Rust toolchain meets the minimum version.
First-Time Setup
# 1. Clone the repo
git clone https://github.com/sprout-rs/sprout.git
cd sprout
# 2. Activate Hermit (optional but recommended)
. ./bin/activate-hermit
# 3. Copy environment config
cp .env.example .env
# 4. Start infrastructure + run migrations
just setup
# 5. Install Git hooks (optional, recommended)
lefthook install
just setup starts Docker services (MySQL on :3306, Redis on :6379,
Typesense on :8108, Adminer on :8082) and runs all pending database
migrations.
Running the Relay
just relay
# or: cargo run -p sprout-relay
The relay listens on ws://localhost:3000 by default. You should see log
output confirming the WebSocket server is up and migrations have run.
Stopping / Resetting
just down # Stop Docker services, keep data
just reset # ⚠️ Wipe all data and recreate the environment
Running Tests
Unit Tests (no infrastructure required)
just test-unit
# or: cargo test --lib
Unit tests are self-contained and run without Docker. They cover event parsing, filter matching, auth logic, workflow YAML parsing, and more.
Integration Tests (requires running infrastructure)
just test
# or: cargo test
Integration tests spin up the relay and exercise the full stack — WebSocket
connections, NIP-42 auth, event ingestion, search indexing, and workflow
execution. just test starts Docker services automatically if they're not
already running.
End-to-End Tests
The sprout-test-client crate contains a WebSocket harness for scenario-level
tests:
cargo run -p sprout-test-client -- --scenario basic-pubsub
Run cargo run -p sprout-test-client -- --help for available scenarios.
CI Gate
Before opening a PR, run the full CI gate locally:
just ci
# Runs: check + unit tests + desktop build + Tauri check
This is the same check that runs in CI. PRs that fail just ci will not be
merged.
Code Style
Formatting
We use rustfmt with the project's rustfmt.toml. Format your code before
committing:
cargo fmt --all
To check without modifying:
cargo fmt --all -- --check
Linting
We use clippy with warnings-as-errors:
cargo clippy --all-targets --all-features -- -D warnings
Fix all clippy warnings before submitting a PR. If you believe a warning is
a false positive, add a targeted #[allow(...)] with a comment explaining
why.
No Unsafe Code
All crates enforce #![deny(unsafe_code)]. Do not add unsafe blocks. If you
believe unsafe is genuinely necessary, open an issue first to discuss the
approach.
Error Handling
- Use
thiserrorfor library error types. - Use
anyhowfor binary / application-level error propagation. - Do not use
unwrap()orexpect()in production code paths. Use?or explicit error handling.unwrap()is acceptable in tests.
Logging and Tracing
Use the tracing crate for all instrumentation. Prefer structured fields
over string interpolation:
// Good
tracing::info!(channel_id = %id, event_kind = kind, "Event ingested");
// Avoid
tracing::info!("Event ingested: channel={id} kind={kind}");
Commit Messages
Follow Conventional Commits:
feat(mcp): add get_feed_actions tool
fix(auth): reject expired NIP-42 challenges
docs(agents): document workflow MCP tools
refactor(db): extract channel queries into channel.rs
test(workflow): add approval gate integration test
The type prefix (feat, fix, docs, refactor, test, chore) is
required. The scope (in parentheses) is optional but encouraged.
Making a Pull Request
Before You Start
- Check open issues and PRs to avoid duplicate work.
- For significant changes, open an issue first to discuss the approach.
- For small fixes (typos, doc improvements, obvious bugs), go ahead and open a PR directly.
What a Good PR Looks Like
-
Focused — one logical change per PR. If you're fixing a bug and refactoring a module, split them into two PRs.
-
Tested — new behavior has tests. Bug fixes include a regression test. If a test is impractical, explain why in the PR description.
-
Documented — public APIs, new event kinds, new MCP tools, and new config variables are documented. Update
README.md,AGENTS.md, orVISION.mdas appropriate. -
CI passing —
just cipasses locally before you push. -
Clear description — the PR description explains:
- What problem this solves (or what feature it adds)
- How it was implemented (key decisions, trade-offs)
- How to test it manually (if applicable)
- Any follow-up work deferred to a future PR
PR Checklist
- [ ] `just ci` passes (fmt + clippy + unit tests)
- [ ] Integration tests pass (`just test`)
- [ ] New public APIs / tools / endpoints are documented
- [ ] CHANGELOG entry added (if user-facing change)
- [ ] No new `unwrap()` in production code paths
- [ ] No new `unsafe` blocks
Review Process
- A maintainer will review your PR within a few business days.
- Address review comments by pushing new commits (don't force-push during review; it makes it hard to see what changed).
- Once approved, a maintainer will squash-merge your PR.
Architecture Overview
See README.md for the full crate map and architecture diagram. The short version:
sprout-relay ← WebSocket server, REST API, event ingestion
sprout-core ← Shared types, event verification, filter matching
sprout-db ← MySQL access layer (sqlx)
sprout-auth ← NIP-42 + OIDC JWT + API token scopes
sprout-pubsub ← Redis fan-out
sprout-search ← Typesense full-text search
sprout-audit ← Tamper-evident hash-chain audit log
sprout-workflow ← YAML-as-code workflow engine
sprout-mcp ← stdio MCP server (agent API surface)
sprout-proxy ← Nostr client compatibility layer
sprout-huddle ← LiveKit integration
sprout-admin ← Operator CLI
sprout-test-client← Integration test harness
Key design principle: The relay is the single source of truth. All state
flows through the event store. Crates communicate through the database and
Redis pub/sub — not through direct function calls across crate boundaries
(with the exception of sprout-core types, which are shared everywhere).
Event kinds are the only switch. Every action in the system — a message, a reaction, a workflow step, a canvas update — is a Nostr event with a kind integer. Adding a new feature means defining a new kind. No breaking changes to existing clients.
How to Add a New Event Kind
-
Define the kind constant in
sprout-core/src/kinds.rs:/// My new event kind — description of what it represents. pub const KIND_MY_FEATURE: u16 = 4XXXX;Pick a kind number in the
40000–49999range (Sprout's reserved range for enterprise extensions). Checkkinds.rsto avoid collisions. -
Define the payload type in
sprout-core/src/types/(if the content field is structured JSON):#[derive(Debug, Serialize, Deserialize)] pub struct MyFeaturePayload { pub field_one: String, pub field_two: Option<u64>, } -
Handle the kind in the relay in
sprout-relay/src/api.rs(or the appropriate handler module). Add a match arm for your kind:KIND_MY_FEATURE => handle_my_feature(&state, &event).await?, -
Persist to the database — if the event needs to be queryable, add a handler in
sprout-db/src/(e.g.,sprout-db/src/my_feature.rs) with the appropriateINSERTandSELECTqueries. -
Index for search (if applicable) — add the kind to the Typesense indexing logic in
sprout-search/src/indexer.rs. -
Audit — the audit log captures all events automatically; no changes needed unless you need custom audit metadata.
-
Write tests — add a unit test for payload serialization in
sprout-coreand an integration test insprout-test-clientthat sends the new event kind and verifies the expected behavior. -
Document — add the kind to the kind reference table in
VISION.mdand updateREADME.mdif it's a user-facing feature.
How to Add a New MCP Tool
MCP tools live in crates/sprout-mcp/src/server.rs. The rmcp crate
provides the #[tool] and #[tool_router] macros.
-
Define a parameter struct:
#[derive(Debug, Serialize, Deserialize, schemars::JsonSchema)] pub struct MyToolParams { /// UUID of the target channel. pub channel_id: String, /// Optional limit on results. #[serde(default)] pub limit: Option<u32>, }Use doc comments (
///) on fields — they become the tool's parameter descriptions in the MCP schema. -
Implement the handler method on
SproutMcpServer:#[tool( name = "my_tool", description = "One-sentence description of what this tool does" )] pub async fn my_tool(&self, Parameters(p): Parameters<MyToolParams>) -> String { // Validate inputs at the boundary if uuid::Uuid::parse_str(&p.channel_id).is_err() { return format!("Error: channel_id '{}' is not a valid UUID", p.channel_id); } // Call the relay via self.client match self.client.get(&format!("/api/channels/{}/my-resource", p.channel_id)).await { Ok(body) => body, Err(e) => format!("Error: {e}"), } } -
The
#[tool_router]macro on theimpl SproutMcpServerblock automatically discovers all#[tool]-annotated methods and registers them. No manual registration needed. -
Update the tool count in
README.mdand add a full parameter table and example toAGENTS.md. -
Write a test — add an integration test in
crates/sprout-mcp/tests/that exercises the new tool end-to-end.
How to Add a New API Endpoint
REST endpoints live in crates/sprout-relay/src/api.rs (or the module
it delegates to after the planned split into src/api/).
-
Define the handler function:
pub async fn get_my_resource( State(state): State<AppState>, AuthenticatedUser(user): AuthenticatedUser, Path(channel_id): Path<Uuid>, ) -> Result<Json<MyResourceResponse>, ApiError> { // Check channel membership state.db.assert_channel_member(channel_id, user.pubkey).await?; // Fetch data let data = state.db.get_my_resource(channel_id).await?; Ok(Json(data)) } -
Register the route in the router (look for
Router::new().route(...)inapi.rsorrouter.rs):.route("/api/channels/:channel_id/my-resource", get(get_my_resource)) -
Add the database query in
sprout-db/src/— follow the existing patterns inchannel.rs,event.rs, etc. -
Handle errors — use the
ApiErrortype insprout-relay/src/error.rs. Map database errors and not-found cases to appropriate HTTP status codes. -
Write tests — add an integration test using the
sprout-test-clientharness oraxum::testutilities. -
Document — if the endpoint is part of the public API surface, add it to the API reference section of
README.mdor a dedicatedAPI.md.
License and CLA
Sprout is licensed under the Apache License, Version 2.0. See LICENSE for the full text.
By submitting a pull request, you agree that your contribution is licensed under the Apache 2.0 license and that you have the right to submit it.
If your employer has rights to intellectual property you create, you may need their sign-off. When in doubt, check with your legal team.
Thank you for contributing to Sprout. Every bug report, documentation fix, and code contribution makes the project better for everyone. 🌱