# ngit-grasp

A [GRASP](https://gitworkshop.dev/danconwaydev.com/grasp) (Git Relays Authorized via Signed-Nostr Proofs) implementation in Rust.

## What's New 🎉

**Full GRASP-02 Implementation Complete!**

ngit-grasp now features a sophisticated proactive sync system that automatically discovers relays, syncs events using NIP-77 negentropy, and hunts for missing git data across clone URLs. Key highlights:

- ✨ **NIP-77 Negentropy**: Efficient set reconciliation with automatic REQ+EOSE fallback
- ✨ **Intelligent Purgatory**: Auto-fetches missing git data from clone URLs (500ms for synced events, 3min for user pushes)
- ✨ **Multi-Maintainer First-Class**: Pushed git data automatically syncs to all maintainer repositories
- ✨ **Smart Throttling**: Respectful rate limiting (5 concurrent, 30/min per domain) with exponential backoff
- ✨ **Live & Historic Sync**: Real-time event streaming plus daily full reconciliation
- ✨ **Connection Health**: Exponential backoff, rate limit detection, dead relay handling

See [GRASP-02 Proactive Sync](docs/explanation/grasp-02-proactive-sync.md) and [Purgatory Git Data Sync](docs/explanation/grasp-02-proactive-sync-purgatory-git-data.md) for details.

## Overview

`ngit-grasp` is a Rust-based implementation of the GRASP protocol, which enables decentralized Git repository hosting with Nostr-based authorization. This implementation combines:

- **Git Smart HTTP Backend**: Serves Git repositories over HTTP
- **Nostr Relay**: Stores and validates repository announcements and state events
- **Integrated Authorization**: Validates Git pushes against Nostr state events without requiring external hooks

Unlike the reference implementation ([ngit-relay](https://gitworkshop.dev/npub15qydau2hjma6ngxkl2cyar74wzyjshvl65za5k5rl69264ar2exs5cyejr/ngit-relay)) which uses nginx + git-http-backend + pre-receive hooks + Khatru (Go), `ngit-grasp` provides a unified Rust service that handles both Git and Nostr protocols natively.

## Status

**Production Ready** - Full GRASP-01 and GRASP-02 implementation with comprehensive test coverage.

## Key Features

- **Pure Rust Implementation**: Single binary, no external dependencies beyond Git itself
- **Integrated Authorization**: Push validation happens inline during the Git receive-pack operation
- **GRASP-01 Compliant**: Core service requirements for Git hosting with Nostr authorization
  - **Flexible Curation & Moderation**: Repository whitelists (GRASP-01 mode), repository blacklists (moderation), and event blacklists (author blocking)
- **GRASP-02 Proactive Sync**: Sophisticated relay-to-relay event and git data synchronization
  - **NIP-77 Negentropy**: Efficient set reconciliation with automatic fallback to REQ+EOSE
  - **Live & Historic Sync**: Real-time event streaming plus catch-up for past events
  - **Smart Throttling**: Respectful rate limiting (5 concurrent, 30/min per domain) with exponential backoff
  - **Multi-Maintainer First-Class**: Internal sync of pushed git data across all maintainer repositories
  - **Intelligent Purgatory**: Auto-fetches missing git data from clone URLs when events arrive first
  - **Discovery-Driven**: Dynamically connects to relays listed in repository announcements
- **Developer-Friendly**: Built with modern Rust async patterns using tokio and actix-web

## Architecture Highlights

### Inline Authorization (GRASP-01)

The key architectural decision is **inline authorization** rather than Git hooks:

- Vendored and customised `git-http-backend` crate provides low-level access to the Git protocol
- We intercept the `git-receive-pack` operation before spawning the Git process
- Push validation happens by checking the Nostr relay for the latest state event
- Only matching pushes are forwarded to the actual Git repository

This approach provides:

- **Better error messages**: Direct HTTP responses vs. hook stderr
- **Simpler deployment**: No hook management or symlinks
- **Tighter integration**: Shared state between Git and Nostr components
- **Easier testing**: Pure Rust unit and integration tests

### Sophisticated Sync System (GRASP-02)

The proactive sync implementation is production-grade with advanced features:

**NIP-77 Negentropy with Intelligent Fallback:**

- Attempts efficient set reconciliation via NIP-77 for full syncs
- Automatically falls back to REQ+EOSE with pagination when negentropy unavailable
- Combines live subscriptions (`limit:0`) with historic catch-up

**Multi-Layer Filter Strategy:**

- **Layer 1**: Repository announcements and maintainer lists (connection-level)
- **Layer 2**: Events tagging repositories (a/A/q tags, batched per 100 repos)
- **Layer 3**: Events tagging root events (e/E/q tags, batched per 100 IDs)

**Connection Health Management:**

- Exponential backoff for failed connections (5s → 1 hour)
- Rate limit detection with 65-second cooldown
- Dead relay handling (24h+ failures → minimal retry)
- Quick reconnect (<15min) vs fresh start (>15min or daily)

**Intelligent Purgatory with Active Git Data Hunting:**

- Events without git data held in-memory for 30 minutes
- **User events**: 3-minute delay (expect git push to follow)
- **Synced events**: 500ms delay (batch burst arrivals, then hunt immediately)
- Proactively fetches missing data from clone URLs every 2 minutes
- Respectful throttling: 5 concurrent, 30 requests/min per domain
- Round-robin fairness across repositories
- Auto-release when data arrives, auto-expire after 30 minutes

**First-Class Multi-Maintainer Support:**

- Git data pushed to one maintainer's repo automatically syncs to all other maintainers
- Shared object databases for storage efficiency (planned)
- Seamless collaboration without manual coordination

See [GRASP-02 Proactive Sync](docs/explanation/grasp-02-proactive-sync.md) for full architectural details.

## GRASP Compliance

### GRASP-01 (Core Service Requirements) ✅

- ✅ NIP-01 compliant Nostr relay at `/`
- ✅ Accepts NIP-34 repository announcements and state events
- ✅ Git Smart HTTP service at `/<npub>/<identifier>.git`
- ✅ Push validation against Nostr state events
- ✅ Multi-maintainer support via recursive maintainer sets
- ✅ Support for `refs/nostr/<event-id>` for PRs
- ✅ Git capabilities: `allow-tip-sha1-in-want`, `allow-reachable-sha1-in-want`, `uploadpack.allowFilter`
- ✅ CORS support for web-based Git clients
- ✅ NIP-11 relay information document
- ✅ **Purgatory**: Events without git data held for 30 minutes, auto-released when data arrives

### GRASP-02 (Proactive Sync) ✅

- ✅ **Relay Discovery**: Automatically connects to relays listed in repository announcements
- ✅ **Event Sync**: Proactive sync from discovered relays using NIP-77 negentropy with REQ+EOSE fallback
  - Live subscriptions (`limit:0`) for real-time event streaming
  - Historic sync with automatic pagination for large result sets
  - Daily full reconciliation to detect drift
  - Connection health tracking with exponential backoff
- ✅ **Git Data Sync**: Automatic fetching of missing git data from clone URLs
  - Smart timing: 3min delay for user events, 500ms for synced events
  - Respectful throttling: 5 concurrent requests, 30/min per domain
  - Round-robin fairness across repositories
  - Exponential backoff with fresh start on new events
- ✅ **Multi-Maintainer Support**: Pushed git data automatically synced to all maintainer repositories
- ✅ **Comprehensive Monitoring**: Prometheus metrics for sync health, bandwidth, and relay status

**See**: [GRASP-02 Proactive Sync](docs/explanation/grasp-02-proactive-sync.md) and [Purgatory Git Data Sync](docs/explanation/grasp-02-proactive-sync-purgatory-git-data.md)

### GRASP-05 (Archive) ✅

- ✅ Accept repositories not listing this instance via configurable whitelist
- ✅ Three whitelist formats: `<npub>`, `<npub>/<identifier>`, `<identifier>`
- ✅ Read-only mirroring with full GRASP-02 sync (git data + Nostr events) - **default behavior**
- ✅ Archive-all mode for complete ecosystem mirrors
- ✅ Fail-fast npub validation at startup

**Archive mode enables backup/mirror operation** - accept repository announcements that don't list your relay, useful for creating archives of critical projects or running comprehensive mirrors. Archived repositories are read-only by default (`NGIT_ARCHIVE_READ_ONLY=true`) with full event and git data sync.

**See**: [GRASP-05 Archive Mode](docs/explanation/grasp-05-archive.md)

## Curation & Moderation

ngit-grasp provides flexible tools for both curation (repository selection) and moderation (blocking spam/abuse):

### Repository Whitelists (Curation)

Control which repositories your relay accepts via two independent whitelist modes:

**Repository Whitelist (GRASP-01 Mode):**
- Only accept announcements that **both** list your service AND match the whitelist
- Three formats: `<npub>`, `<npub>/<identifier>`, `<identifier>`
- Environment: `NGIT_REPOSITORY_WHITELIST=npub1alice...,bitcoin-core`
- Use case: Curated relay accepting specific projects/developers

**Archive Whitelist (GRASP-05 Mode):**
- Accept announcements matching the whitelist **even if they don't list your service**
- Same three formats as repository whitelist
- Environment: `NGIT_ARCHIVE_WHITELIST=npub1satoshi...,linux`
- Use case: Backup/mirror relay for critical projects
- Default: Read-only mode (`NGIT_ARCHIVE_READ_ONLY=true`)

Both whitelists support flexible matching:
```bash
# Accept all repos from specific developer
NGIT_REPOSITORY_WHITELIST=npub1alice...

# Accept specific repository
NGIT_REPOSITORY_WHITELIST=npub1alice.../my-project

# Accept repos with specific identifier (any author)
NGIT_REPOSITORY_WHITELIST=bitcoin-core
```

### Blacklists (Moderation)

Block unwanted content without affecting your curation policy:

**Repository Blacklist:**
- Block specific repositories/developers/identifiers
- **Takes precedence over ALL whitelists** (checked first)
- Three formats: `<npub>`, `<npub>/<identifier>`, `<identifier>`
- Environment: `NGIT_REPOSITORY_BLACKLIST=npub1spam...,malware-repo`
- Use case: Block spam/malware repos while maintaining whitelist curation

**Event Blacklist:**
- Block **ALL events** from specific authors (npubs)
- **Takes precedence over ALL other validation** (checked first)
- Applies to all event types: announcements, state events, PRs, comments, etc.
- Events never reach relay storage or purgatory
- Environment: `NGIT_EVENT_BLACKLIST=npub1spammer...,npub1abuser...`
- Use case: Block abusive users completely

### Precedence & Interaction

Validation order (from first to last):

1. **Event Blacklist** → Reject if author is blacklisted (ALL event types)
2. **Repository Blacklist** → Reject if repository/npub/identifier is blacklisted (announcements only)
3. **Repository Whitelist** → Accept if announcement lists service AND matches whitelist
4. **Archive Whitelist** → Accept if announcement matches whitelist (even without listing service)
5. **Default GRASP-01** → Accept if announcement lists service (no whitelist configured)

Examples:
```bash
# Curated relay blocking spam
NGIT_REPOSITORY_WHITELIST=npub1alice...,npub1bob...
NGIT_REPOSITORY_BLACKLIST=npub1alice.../spam-repo
NGIT_EVENT_BLACKLIST=npub1spammer...
# Result: Accept Alice & Bob's repos EXCEPT Alice's spam-repo, block all events from spammer

# Archive relay with moderation
NGIT_ARCHIVE_WHITELIST=bitcoin-core,linux
NGIT_EVENT_BLACKLIST=npub1abuser...
# Result: Mirror bitcoin-core and linux projects, block all events from abuser

# Public relay with spam protection
NGIT_EVENT_BLACKLIST=npub1spam1...,npub1spam2...
# Result: Accept all GRASP-01 repos, block all events from spammers
```

**Privacy & Transparency:**
- Blacklists are **not advertised** in NIP-11 metadata (operational, not curation policy)
- Rejected events receive specific error messages for operator debugging
- No client-visible indication that blacklists are in use

**See**: [Configuration Reference](docs/reference/configuration.md) for complete details

## Defensive Measures & Rate Limiting

ngit-grasp implements multiple layers of defense against abuse, spam, and denial-of-service attacks:

**Per-Connection Rate Limits:**
- Max 500 concurrent subscriptions per connection
- Max 60 events published per minute per connection
- Built-in to rust-nostr relay-builder

**Per-IP Connection Monitoring:**
- Tracks connections per IP address (default threshold: 10)
- Flags potential abusers in logs and metrics
- **Does NOT enforce limits** (monitoring only)
- Privacy-preserving (IP addresses never exposed in Prometheus)

**Content Filtering (Blacklists/Whitelists):**
- **Event blacklist** - Block ALL events from specific authors (npubs)
- **Repository blacklist** - Block specific repositories/developers/identifiers
- **Repository whitelist** - Curate which repositories are accepted (GRASP-01 mode)
- **Archive whitelist** - Mirror specific repositories (GRASP-05 mode)
- See [Curation & Moderation](#curation--moderation) section above for details

**Relay Sync Protection (GRASP-02):**
- **Exponential backoff** - Failed connections: 5s → 10s → 20s → ... → 1 hour max
- **Naughty list** - Track relays with infrastructure issues separately (12h expiry)
- **Rate limit detection** - Auto 65s cooldown when remote relays rate limit us
- **Domain throttling** - Max 5 concurrent, 30/min per domain for git data fetching

**Event Validation:**
- Strict GRASP-01 protocol validation via WritePolicy plugin system
- Extensible for custom validation logic (has access to client IP address)

**Total Connection Limit:**
- Max 500 total connections (configurable via `NGIT_MAX_CONNECTIONS`)
- Prevents connection exhaustion DoS attacks

**Not Implemented:**
- Per-IP connection limits (only monitored, not enforced)
- Per-IP event rate limits (tracked per connection, not per IP)

**See**: [Defensive Measures](docs/explanation/defensive-measures.md) for complete details and future enhancements.

## Roadmap

### GRASP-02 Enhancements

**Proactive Sync Plus:**

- 🔄 Scan read/write relays of repo/PR/Patch/Issue authors for related comments
- 🔄 Stricter anti-spam mechanisms for author relay events
- 🔄 Periodic scanning of relays in User Grasp Lists for announcements listing our relay

### Data Efficiency

**Git Object Deduplication:**

- 🔄 Shared object database across repositories
- 🔄 Use `GIT_ALTERNATE_OBJECT_DIRECTORIES` or `.git/objects/info/alternates`
- 🔄 Significant storage savings for multi-maintainer repositories

### Monitoring & Observability

ngit-grasp exposes comprehensive Prometheus metrics at `/metrics` for:

**Git Operations:**

- Clone/fetch/push rates and bandwidth
- Authorization results (accepted/rejected)
- Top N repositories by bandwidth

**Nostr Events:**

- WebSocket connections (active, unique IPs, flagged abusers)
- Events received, stored, rejected by kind
- Purgatory status (events waiting for git data)

**Sync Health (GRASP-02):**

- Per-relay connection status and health states
- Event sync rates and bandwidth
- Git data fetch attempts and success rates
- Domain throttling metrics

**Configuration Options:**

| Option                     | CLI Flag                                      | Environment Variable                             | Default |
| -------------------------- | --------------------------------------------- | ------------------------------------------------ | ------- |
| Metrics enabled            | `--metrics-enabled`                           | `NGIT_METRICS_ENABLED`                           | `true`  |
| Connection abuse threshold | `--metrics-connection-per-ip-abuse-threshold` | `NGIT_METRICS_CONNECTION_PER_IP_ABUSE_THRESHOLD` | `10`    |
| Top N repos                | `--metrics-top-n-repos`                       | `NGIT_METRICS_TOP_N_REPOS`                       | `10`    |

**Privacy:** IP addresses are never exposed in metrics - only aggregate counts.

See [Monitoring Overview](docs/explanation/monitoring.md) and [Prometheus Setup Guide](docs/how-to/prometheus-setup.md) for deployment.

### Delete Events

Git data related to deleted Repositories should be archvied (and deleted after 90 days), also events related to ONLY this repository.

Delete Request Disrepector - so that events dont get removes - its problematic if someone elses PR event and comments gets deleted if the owner deletes the repo. having at least some archival grasp servers retaining it so it can be recovered is important. also we need to make left-pad impossible.

[Deletion Request Archecture](docs/explanation/deletion-request.md) designed by not yet implemented.

### Grasp Server Removed from Announcement Event

Unless GRASP-05, This should cause the git data and events related ONLY to this repository to be archived (and deleted after 90 days).

### Mitigate DoS attack vector

Grasp servers can be DoS by pushing large amounts of git data to `refs/nostr/<event-id>` without having to first submit a signed nostr event. operators must temporarily disable pushes to `refs/nostr/*` without having recieved a signed event. This breaks the flow of sending PR / Update events in NIP-34 as the client doesnt know if the grasp server will accept git data / event so might include it as a server hint in `clone` without knowing whether the server will accept the data. Could an ephemeral event be sent to authorise or is that too complicated? Maybe require NIP-42 auth and authorise that IP address for the push based on WoT?

### Reject Commits with Secrets

This a useful feature of other git servers.

### Store all user grasp lists (for better grasp discovery)

✅ **Implemented**: Kind 10317 (User Grasp List) events are now accepted and synced from all relays for better GRASP repository discovery.

**Future enhancement**: We aspire to also accept and weekly sync kind 10002 (user relay lists) and kind 0 (user metadata) events, but only for authors of accepted events. This would require an additional state-driven layer 2 filter (see Roadmap in GRASP-02 Proactive Sync documentation).

**Future enhancement**: should we periodically scan relays in UserGraspLists to check for announcements that list our relay?

## Technology Stack

- **Rust**: Core language
- **actix-web**: HTTP server framework
- **git-http-backend**: Git protocol handling but vendored and customised for authorisation logic
- **nostr-relay-builder**: Nostr relay infrastructure from rust-nostr
- **nostr-sdk**: Nostr event handling and validation
- **tokio**: Async runtime

## Quick Start

```bash
# install ngit
curl -Ls https://ngit.dev/install.sh | bash

# Clone the repository
git clone nostr://danconwaydev.com/relay.ngit.dev/ngit-grasp
cd ngit-grasp

# Build (using Nix for reproducible environment)
nix develop -c cargo build --release

# Configure
cp .env.example .env
# Edit .env with your settings
# Required: NGIT_DOMAIN=your-domain.com
# Optional: NGIT_SYNC_BOOTSTRAP_RELAY_URL=wss://relay.example.com

# Run
nix develop -c cargo run --release

# Run tests
nix develop -c cargo test --lib
```

**What happens on startup:**

- Git HTTP server starts on configured bind address
- Nostr relay begins accepting WebSocket connections
- If bootstrap relay configured, sync system connects and discovers repositories
- Purgatory system activates, ready to hunt for missing git data
- Prometheus metrics exposed at `/metrics`

**Don't have Nix?** See [Getting Started Tutorial](docs/tutorials/getting-started.md) for alternative setup methods.

## Configuration

Configuration is loaded with the following priority (highest to lowest):

1. **CLI flags** (e.g., `--domain example.com`)
2. **Environment variables** (e.g., `NGIT_DOMAIN=example.com`)
3. **.env file** (loaded automatically if present)
4. **Built-in defaults**

This means CLI flags always take precedence over environment variables, which take precedence over `.env` file values.

### CLI Usage

```bash
# View all options with defaults
ngit-grasp --help

# Run with CLI flags (override everything else)
ngit-grasp --domain relay.example.com --relay-owner-nsec nsec1... --bind-address 0.0.0.0:7334

# Mix CLI flags with environment variables
NGIT_RELAY_OWNER_NSEC=nsec1... ngit-grasp --domain relay.example.com
```

### Configuration Options

#### Core Settings

| Option            | CLI Flag              | Environment Variable     | Default                                      |
| ----------------- | --------------------- | ------------------------ | -------------------------------------------- |
| Domain            | `--domain`            | `NGIT_DOMAIN`            | (required)                                   |
| Relay owner nsec  | `--relay-owner-nsec`  | `NGIT_RELAY_OWNER_NSEC`  | `.relay-owner.nsec` file (auto-generated)    |
| Relay name        | `--relay-name`        | `NGIT_RELAY_NAME`        | `${domain} grasp relay`                      |
| Relay description | `--relay-description` | `NGIT_RELAY_DESCRIPTION` | `Git Nostr Relay - a grasp implementation`   |
| Git data path     | `--git-data-path`     | `NGIT_GIT_DATA_PATH`     | `./data/git` (temp dir for memory backend)   |
| Relay data path   | `--relay-data-path`   | `NGIT_RELAY_DATA_PATH`   | `./data/relay` (temp dir for memory backend) |
| Bind address      | `--bind-address`      | `NGIT_BIND_ADDRESS`      | `127.0.0.1:7334` (NGIT on phone keypad)      |
| Database backend  | `--database-backend`  | `NGIT_DATABASE_BACKEND`  | `lmdb`                                       |

#### GRASP-02 Sync Settings

| Option                    | CLI Flag                                | Environment Variable                       | Default         |
| ------------------------- | --------------------------------------- | ------------------------------------------ | --------------- |
| Bootstrap relay           | `--sync-bootstrap-relay-url`            | `NGIT_SYNC_BOOTSTRAP_RELAY_URL`            | (optional)      |
| Base backoff              | `--sync-base-backoff-secs`              | `NGIT_SYNC_BASE_BACKOFF_SECS`              | `5` seconds     |
| Max backoff               | `--sync-max-backoff-secs`               | `NGIT_SYNC_MAX_BACKOFF_SECS`               | `3600` (1 hour) |
| Disconnect check interval | `--sync-disconnect-check-interval-secs` | `NGIT_SYNC_DISCONNECT_CHECK_INTERVAL_SECS` | `60` seconds    |
| Disable negentropy        | `--sync-disable-negentropy`             | `NGIT_SYNC_DISABLE_NEGENTROPY`             | `false`         |
| Batch window              | N/A                                     | `NGIT_SYNC_BATCH_WINDOW_MS`                | `5000` ms       |

#### Curation & Moderation Settings

| Option               | CLI Flag                    | Environment Variable           | Default   |
| -------------------- | --------------------------- | ------------------------------ | --------- |
| Repository whitelist | `--repository-whitelist`    | `NGIT_REPOSITORY_WHITELIST`    | (empty)   |
| Archive whitelist    | `--archive-whitelist`       | `NGIT_ARCHIVE_WHITELIST`       | (empty)   |
| Archive all          | `--archive-all`             | `NGIT_ARCHIVE_ALL`             | `false`   |
| Archive read-only    | `--archive-read-only`       | `NGIT_ARCHIVE_READ_ONLY`       | (auto)    |
| Repository blacklist | `--repository-blacklist`    | `NGIT_REPOSITORY_BLACKLIST`    | (empty)   |
| Event blacklist      | `--event-blacklist`         | `NGIT_EVENT_BLACKLIST`         | (empty)   |

**Sync Notes:**

- **Bootstrap relay**: Optional starting point for relay discovery. System automatically discovers additional relays from repository announcements. URL scheme is optional - if not provided, `wss://` is assumed (e.g., `git.shakespeare.diy` → `wss://git.shakespeare.diy`).
- **Backoff settings**: Controls exponential backoff for failed connections (`base * 2^(failures-1)`, capped at max).
- **Negentropy**: Can be disabled for testing REQ+EOSE fallback behavior.
- **Batch window**: Self-subscriber batches events for this duration before triggering sync filters.

### Database Backends

- `lmdb`: LMDB backend (default, persistent, general purpose)
- `memory`: In-memory database (fastest, no persistence - uses temp directories)

> **Note:** When using the `memory` backend, git data are automatically stored in temporary directories for ephemeral testing.

### Example: Production Deployment

```bash
# Using environment variables (recommended for production)
export NGIT_DOMAIN=gitnostr.com
export NGIT_RELAY_OWNER_NSEC=nsec1...  # Or let it auto-generate from .relay-owner.nsec
export NGIT_BIND_ADDRESS=0.0.0.0:7334
export NGIT_DATABASE_BACKEND=lmdb

# Optional: Enable proactive sync from a bootstrap relay
export NGIT_SYNC_BOOTSTRAP_RELAY_URL=wss://relay.damus.io

# Optional: Tune sync behavior
export NGIT_SYNC_BASE_BACKOFF_SECS=5      # Start backoff at 5 seconds
export NGIT_SYNC_MAX_BACKOFF_SECS=3600    # Cap backoff at 1 hour

ngit-grasp
```

**Production Tips:**

- Set `NGIT_SYNC_BOOTSTRAP_RELAY_URL` to a well-connected relay for initial repository discovery
- The system will automatically discover and connect to additional relays listed in repository announcements
- Monitor sync health via Prometheus metrics at `/metrics`
- Purgatory will automatically fetch missing git data from clone URLs

### Example: Development

```bash
# Using .env file
cp .env.example .env
# Edit .env with your settings
ngit-grasp

# Or override specific values with CLI flags
ngit-grasp --domain localhost:3000 --bind-address 127.0.0.1:3000
```

## Documentation

We use the **[Diátaxis](https://diataxis.fr/)** framework for documentation:

- **[Tutorials](docs/tutorials/)** - Learn by doing (Getting Started, First Audit)
- **[How-To Guides](docs/how-to/)** - Solve specific problems (Deploy, Configure)
- **[Reference](docs/reference/)** - Look up technical details (Config, Protocols)
- **[Explanation](docs/explanation/)** - Understand concepts (Architecture, Decisions)

**Start here:** [Documentation Index](docs/README.md)

## Development

See [Architecture Overview](docs/explanation/architecture.md) for system design and [Test Strategy](docs/reference/test-strategy.md) for testing approach.

### Running Tests

We have two test suites:

**1. Main Project Tests (ngit-grasp)**

```bash
# Run unit tests (no external dependencies)
nix develop -c cargo test --lib

# Run all integration tests (automatic relay management)
nix develop -c cargo test --test nip01_compliance --test nip34_announcements

# Run NIP-01 compliance tests
nix develop -c cargo test --test nip01_compliance

# Run NIP-34 announcement tests
nix develop -c cargo test --test nip34_announcements

# With detailed output
nix develop -c cargo test --test nip01_compliance -- --nocapture

# Run specific test
nix develop -c cargo test --test nip01_compliance test_nip01_smoke
```

**Integration tests automatically:**

- Start a fresh relay instance
- Run compliance tests using grasp-audit library
- Clean up when done
- No manual relay management needed!

**2. GRASP Audit Tool (grasp-audit)**

The audit tool tests GRASP compliance of any relay (including ours or external ones).

```bash
# Enter grasp-audit directory
cd grasp-audit

# Run unit tests
nix develop -c cargo test

# Test against any relay (including external ones)
nix develop -c cargo run -- --url wss://relay.example.com

# Or test against any external relay:
nix develop -c cargo run -- --url wss://relay.example.com
```

### Development Commands

```bash
# Run with logging
RUST_LOG=debug nix develop -c cargo run

# Check code
nix develop -c cargo clippy
nix develop -c cargo fmt --check

# Generate test coverage (requires tarpaulin)
nix develop -c cargo tarpaulin --out Html
```

**Note:** Always use `nix develop` to ensure the correct build environment. See [docs/how-to/nix-flakes.md](docs/how-to/nix-flakes.md) for details.

## Project Structure

```
ngit-grasp/
├── src/
│   ├── main.rs              # Entry point, server setup
│   ├── lib.rs               # Library exports
│   ├── config.rs            # Configuration (core + sync settings)
│   ├── git/
│   │   ├── mod.rs           # Git module + repository operations
│   │   ├── handlers.rs      # Git HTTP handlers
│   │   ├── authorization.rs # Push validation logic (checks DB + purgatory)
│   │   ├── protocol.rs      # Git protocol encoding
│   │   └── subprocess.rs    # Git subprocess management
│   ├── nostr/
│   │   ├── mod.rs           # Nostr module
│   │   ├── builder.rs       # Relay builder + Nip34WritePolicy
│   │   ├── events.rs        # Event parsing and validation
│   │   └── policy/          # Sub-policies (split for maintainability)
│   │       ├── mod.rs       # Policy module exports
│   │       ├── announcement.rs  # Repository announcement validation
│   │       ├── state.rs     # State event validation + ref alignment
│   │       ├── pr_event.rs  # PR/PR Update validation
│   │       └── related.rs   # Forward/backward reference checking
│   ├── sync/                # GRASP-02 Proactive Sync (relay-to-relay)
│   │   ├── mod.rs           # SyncManager, main loop, data structures
│   │   ├── algorithms.rs    # derive_relay_targets(), compute_actions()
│   │   ├── filters.rs       # 3-layer filter building (announcements, repos, events)
│   │   ├── health.rs        # RelayHealthTracker (backoff, rate limits)
│   │   ├── relay_connection.rs # RelayConnection, event loop lifecycle
│   │   ├── self_subscriber.rs  # SelfSubscriber (batched event discovery)
│   │   └── metrics.rs       # SyncMetrics for Prometheus
│   ├── purgatory/           # In-memory holding area for events awaiting git data
│   │   ├── mod.rs           # Purgatory core (state/PR storage, 30min expiry)
│   │   ├── helpers.rs       # State event ref matching, PR lookup
│   │   ├── processing.rs    # Unified git data processing (push + sync paths)
│   │   └── sync/            # Proactive git data fetching
│   │       ├── mod.rs       # Public API (enqueue, main loop)
│   │       ├── loop.rs      # Sync loop (1s interval, debounced delays)
│   │       ├── functions.rs # Core sync logic (try URLs, handle results)
│   │       ├── queue.rs     # SyncQueue (backoff, fresh start on new events)
│   │       ├── throttle.rs  # DomainThrottle (5 concurrent, 30/min, round-robin)
│   │       └── context.rs   # SyncContext trait + mock for testing
│   ├── http/
│   │   ├── mod.rs           # HTTP module
│   │   ├── landing.rs       # Landing page handler
│   │   └── nip11.rs         # NIP-11 relay info document
│   └── metrics/
│       ├── mod.rs           # Prometheus metrics (Git, Nostr, Sync)
│       ├── bandwidth.rs     # Bandwidth tracking
│       └── connection.rs    # Connection tracking
├── docs/                    # Documentation (Diátaxis framework)
│   ├── explanation/         # Architecture, decisions, GRASP-02 deep-dives
│   ├── how-to/              # Deployment, configuration guides
│   ├── tutorials/           # Getting started, first steps
│   └── reference/           # API docs, test strategy
├── tests/                   # Integration tests (NIP-01, NIP-34, purgatory)
├── grasp-audit/             # Compliance audit subproject
└── README.md
```

## Comparison with ngit-relay

| Feature             | ngit-relay (Go)                           | ngit-grasp (Rust)                                    |
| ------------------- | ----------------------------------------- | ---------------------------------------------------- |
| Language            | Go                                        | Rust                                                 |
| Components          | nginx + git-http-backend + hooks + Khatru | Single integrated binary                             |
| Authorization       | Pre-receive Git hook                      | Inline during receive-pack                           |
| GRASP-01            | ✅ Complete                               | ✅ Complete                                          |
| GRASP-02 Event Sync | ✅ Limited                                | ✅ Advanced (NIP-77 negentropy + fallback)           |
| GRASP-02 Git Sync   | ✅ Basic                                  | ✅ Automatic purgatory hunting                       |
| Multi-Maintainer    | ✅ Supported                              | ✅ First-class (auto-sync across repos)              |
| Purgatory           | ✅ 24-hour expiry                         | ✅ 30-minute expiry + proactive git data fetching    |
| Health Tracking     | Basic                                     | Advanced (exponential backoff, rate limit detection) |
| Deployment          | Docker + supervisord                      | Single binary                                        |
| Testing             | Go tests + shell scripts                  | Rust unit + integration tests                        |
| Performance         | Good                                      | Excellent (zero-copy, async)                         |
| Monitoring          | Basic logs                                | Comprehensive Prometheus metrics                     |

## Contributing

Contributions welcome! Please:

1. Read [docs/explanation/architecture.md](docs/ARCHITECTURE.md)
2. Open an issue to discuss major changes
3. Follow Rust conventions and run `cargo fmt` + `cargo clippy`
4. Add tests for new functionality

## License

MIT License - see [LICENSE](LICENSE) for details

## Related Projects

- [GRASP Protocol](https://gitworkshop.dev/danconwaydev.com/grasp) - Protocol specification
- [ngit-relay](https://gitworkshop.dev/npub15qydau2hjma6ngxkl2cyar74wzyjshvl65za5k5rl69264ar2exs5cyejr/ngit-relay) - Reference implementation in Go
- [ngit](https://gitworkshop.dev/ngit) - Nostr Git plugin for git CLI
- [NIP-34](https://nips.nostr.com/34) - Git Stuff (Nostr protocol)

## Acknowledgments

- Reference implementation by [@DanConwayDev](https://gitworkshop.dev/danconwaydev.com)
- [rust-nostr](https://github.com/rust-nostr/nostr) team for excellent Nostr libraries
- Git community for the Smart HTTP protocol