ngit-grasp/docs/explanation/architecture.md

ngit-grasp Architecture

Transient collections, queues, tasks, and peer-selected identifiers follow the ownership and cleanup invariants in Peer-controlled state ownership.

Executive Summary

ngit-grasp implements the GRASP protocol in Rust with inline authorization rather than Git hooks. Git push operations are intercepted and validated at the HTTP handler level before reaching the Git repository, eliminating the need for pre-receive hooks.

Git object storage is organized into identifier families shared by the owner-specific and GRASP-06 repository views. The local filesystem remains the default durable backend; S3-compatible storage is opt-in. See Identifier-family Git object storage for the storage, durability, no-GC, and startup-migration invariants.

System Architecture

┌─────────────────────────────────────────────────────────────┐
│                        ngit-grasp                           │
│                     (Single Rust Binary)                    │
├─────────────────────────────────────────────────────────────┤
│                                                             │
│  ┌──────────────────┐              ┌──────────────────┐   │
│  │   HTTP Router    │              │  Nostr Relay     │   │
│  │     (Hyper)      │              │  (nostr-relay-   │   │
│  │                  │              │   builder)       │   │
│  └────────┬─────────┘              └────────┬─────────┘   │
│           │                                 │             │
│           │                                 │             │
│  ┌────────▼──────────────────────────────────▼─────────┐  │
│  │           Shared State & Storage                    │  │
│  │  ┌──────────────┐  ┌──────────────┐                │  │
│  │  │  Repository  │  │  Event Store │                │  │
│  │  │  Manager     │  │  (LMDB/NDB)  │                │  │
│  │  └──────────────┘  └──────────────┘                │  │
│  └─────────────────────────────────────────────────────┘  │
│                                                             │
│  ┌──────────────────────────────────────────────────────┐  │
│  │            Git Protocol Handler                      │  │
│  │                                                      │  │
│  │  1. Receive git-receive-pack request                │  │
│  │  2. Parse ref updates from request                  │  │
│  │  3. Query Nostr relay for state event               │  │
│  │  4. Validate refs against state                     │  │
│  │  5. If valid: spawn git-receive-pack                │  │
│  │  6. If invalid: return HTTP error                   │  │
│  │                                                      │  │
│  └──────────────────────────────────────────────────────┘  │
│                                                             │
└─────────────────────────────────────────────────────────────┘
         │                                      │
         │ HTTP/Git                             │ WebSocket/Nostr
         ▼                                      ▼
    Git Clients                            Nostr Clients

Component Design

1. Main Server (src/main.rs + src/server.rs)

Server startup is split across two layers: main.rs owns binary-only concerns, while RelayServer in server.rs owns the reusable relay runtime:

src/main.rs — binary-only concerns:

• Initialize configuration from CLI/environment (clap + dotenvy)
• Install the global tracing subscriber
• Load/generate the relay owner key file (.relay-owner.nsec)
• Translate OS signals (SIGINT/SIGTERM) into a shutdown future

src/server.rs — RelayServer, the shared runtime:

• Bind the TCP listener (supports :0 for kernel-assigned ports; the resolved address back-fills bind_address and, if empty, domain)
• Initialize Nostr relay builder with custom Nip34WritePolicy
• Set up shared storage (LMDB or Memory), purgatory, sync manager, and background maintenance tasks
• Seed the relay owner's minimal kind-0 bot profile and single-relay kind-10002 read/write list when absent — stored identity events are never overwritten, and a kind with no local copy is seeded only once a configured user-index relay is reachable and confirms it holds no identity of that kind — then publish in the background: no identity event, stored or generated, is sent before at least one user-index relay has been checked for its kind, every send is preceded by a per-relay re-check, and an identity found on an index is adopted locally instead of overwritten. Transient failures retry with a capped backoff, and in private mode the identity stays local so the relay's existence is never advertised
• Atomically checkpoint purgatory and rejected-event recovery state every 60 seconds without consuming the checkpoint during restore
• Serve HTTP + WebSocket until a caller-supplied shutdown future resolves, then stop background mutation, persist a final state snapshot (purgatory and rejected-events cache), and clean up placeholder refs

Key Dependencies:

hyper = "1"
tokio = { version = "1", features = ["full"] }
nostr-relay-builder = "0.45.0-alpha.3"
nostr-sdk = "0.45.0-alpha.3"
nostr-lmdb = "0.45.0-alpha.3"

2. HTTP Module (src/http/mod.rs)

Responsibilities:

• Route HTTP requests to appropriate handlers
• WebSocket upgrade for Nostr relay at /
• Git Smart HTTP endpoints at /<npub>/<identifier>.git/*
• Landing pages, the root-path-only NIP-05 _@domain well-known mapping, and path-aware NIP-11 document serving that omits NIP-05 below the domain root
• CORS headers on all responses (GRASP-01 requirement)

Key Implementation Details:

// CORS headers required by GRASP-01 specification
const CORS_ALLOW_ORIGIN: &str = "*";
const CORS_ALLOW_METHODS: &str = "GET, POST";
const CORS_ALLOW_HEADERS: &str = "Content-Type";

/// Add CORS headers to a response builder
fn add_cors_headers(builder: http::response::Builder) -> http::response::Builder {
    builder
        .header("Access-Control-Allow-Origin", CORS_ALLOW_ORIGIN)
        .header("Access-Control-Allow-Methods", CORS_ALLOW_METHODS)
        .header("Access-Control-Allow-Headers", CORS_ALLOW_HEADERS)
}

See src/http/mod.rs:29-84 for the full CORS implementation.

The relay-owner key is also a trusted service author in Nip34WritePolicy, with deliberately narrow scope. Owner-signed events skip the event blacklist but still pass the NIP-09/NIP-62 deletion gate, so a replayed copy of a retracted owner event cannot undo its tombstone, and every kind with a dedicated admission policy takes its normal path: owner-signed NIP-34 announcements, state events, and PRs are validated, ref-aligned, and routed through purgatory exactly like anyone else's, while the relay's own kind 0/10002 identity is always accepted. Trust applies only to owner-signed kinds that would otherwise fall through to the generic related-event rejection — ngit-ci coordinator advertisements, for example, intentionally have no repository root tag. Owner-authored NIP-09/NIP-62 requests still run through their normal lifecycle handlers so CI status retractions and other deletions retain their protocol effects. Because the blacklist cannot block the owner key, the only remediation for a compromised relay-owner nsec is rotating the key.

3. Git Module (src/git/)

handlers.rs - Git HTTP Handlers

Implements handlers for Git Smart HTTP protocol:

/// Handle GET /info/refs?service=git-{upload,receive}-pack
pub async fn handle_info_refs(
    repo_path: PathBuf,
    service: GitService,
) -> Result<Response<Full<Bytes>>, GitError>

/// Handle POST /git-upload-pack (clone/fetch)
pub async fn handle_upload_pack(
    repo_path: PathBuf,
    body: Bytes,
) -> Result<Response<Full<Bytes>>, GitError>

/// Handle POST /git-receive-pack (push)
/// THIS IS WHERE THE MAGIC HAPPENS - validates against state before accepting
pub async fn handle_receive_pack(
    repo_path: PathBuf,
    body: Bytes,
    database: SharedDatabase,
    npub: &str,
    identifier: &str,
) -> Result<Response<Full<Bytes>>, GitError>

See src/git/handlers.rs:22-98 for the info-refs implementation.

authorization.rs - Push Validation

Core Logic:

/// Get authorization info for a repository owner
pub async fn get_authorization_for_owner(
    database: &SharedDatabase,
    pubkey: &PublicKey,
    identifier: &str,
) -> Result<AuthorizationResult, AuthorizationError>

/// Validate that pushed refs match the authorized state
pub fn validate_push_refs(
    pushed_refs: &[PushedRef],
    state: &RepositoryState,
) -> Result<(), AuthorizationError>

/// Validate refs/nostr/<event-id> pushes
pub fn validate_nostr_ref_pushes(
    pushed_refs: &[PushedRef],
    database: &SharedDatabase,
) -> Result<(), AuthorizationError>

4. Nostr Module (src/nostr/)

builder.rs - Relay Configuration

The Nip34WritePolicy is the core event validation logic:

/// NIP-34 Write Policy with Full GRASP-01 Event Validation
///
/// Validates all events according to GRASP-01 specification:
/// - Repository announcements must list service in clone and relays tags
///   EXCEPTION: Recursive maintainer announcements are accepted even without
///   listing the service, to enable maintainer chain discovery and GRASP-02 sync
/// - Repository state announcements must have valid structure
/// - Other events must reference accepted repositories or events
/// - Forward references are supported (events referenced by accepted events)
/// - Orphan events with no valid references are rejected
pub struct Nip34WritePolicy {
    ctx: PolicyContext,
    announcement_policy: AnnouncementPolicy,
    state_policy: StatePolicy,
    pr_event_policy: PrEventPolicy,
    related_event_policy: RelatedEventPolicy,
    deletion: DeletionService,
}

See src/nostr/builder.rs:38-78 for the full policy struct.

lifecycle.rs - Repository Lifecycle Coordination

RepositoryLifecycle is the shared facade for per-repository lifecycle locks. Git Smart HTTP serving takes shared read locks through this facade, while deletion and recovery take exclusive write locks through the same facade. The lock map and lock-file support are owned by the lifecycle module itself, so repository runtime coordination is independent of holding/deletion storage.

HTTP git serving  -> RepositoryLifecycle
Deletion/recovery -> RepositoryLifecycle
Holding cleanup   -> RepositoryLifecycle
Manual ejection   -> RepositoryLifecycle
RepositoryLifecycle -> RepositoryLifecycleLocks

lifecycle/deletion/ - Deletion Lifecycle

Deletion handling is owned by ngit-grasp policy code rather than backend auto-processing. NIP-09 deletion requests, NIP-62 request-to-vanish events, repository blacklist/whitelist parity, and runtime service de-listing all flow through the same lifecycle: gate future writes with tombstones where applicable, move removed events into holding, cascade-delete repository-related events that lose their accepted-reference path, archive/remove the related git repositories when a served scope disappears, and keep nostr state aligned with git data. Operators can opt into archival behaviour with NGIT_DELETION_REQUEST_DISRESPECTOR, which stores but does not act on user deletion/vanish requests.

Full details: Repository Lifecycle.

events.rs - Event Parsing

Provides structures for parsing NIP-34 events:

/// Parsed repository announcement (Kind 30617)
pub struct RepositoryAnnouncement { ... }

/// Parsed repository state (Kind 30618)
pub struct RepositoryState { ... }

policy/state.rs - State Event Authorization

State events undergo authorization checks at multiple points:

/// State event authorization checks:
/// 1. Announcement must exist for the repository identifier
/// 2. Author must be in maintainer set of accepted announcement
/// 3. Validated on arrival, announcement acceptance, and git data arrival

Defense-in-depth authorization:

• On arrival (StatePolicy): Initial authorization check
• On announcement acceptance: Purgatory re-evaluation of waiting state events
• On git data arrival: Final authorization before database save

5. Purgatory System (src/purgatory/)

The purgatory system solves two related problems:

1. "Which arrives first?" — Either nostr events or git pushes can arrive in any order. Purgatory holds events awaiting their git data counterparts.
2. Misleading empty repository announcements — New announcements are held in purgatory until git data arrives, ensuring clients are never served announcements for repos with no content.

Design Document: See purgatory-design.md for complete design specifications.

Architecture

/// Main purgatory structure with separate stores per event type
pub struct Purgatory {
    /// Announcement events (kind 30617) indexed by (owner, identifier)
    /// Held until git data proves content exists
    announcement_purgatory: DashMap<(PublicKey, String), AnnouncementPurgatoryEntry>,

    /// State events (kind 30618) indexed by repository identifier
    state_events: DashMap<String, Vec<StatePurgatoryEntry>>,
    
    /// PR events (kind 1617/1618) or placeholders indexed by event ID
    pr_events: DashMap<String, PrPurgatoryEntry>,
}

Key Design Principles:

1. Separate Storage: Each event type uses a different indexing strategy

   • Announcements: Indexed by (pubkey, identifier) (unique per owner)
   • State events: Indexed by identifier (multiple events can wait for same repo)
   • PR events: Indexed by event_id (one-to-one mapping)

2. Announcement Purgatory: New announcements are held until git data arrives

   • Bare repo created immediately so pushes can succeed
   • Announcement promoted to database only when git data proves content exists
   • Two-phase soft expiry: bare repo deleted at 30 min, event retained 24h for revival

3. Late Binding: State event refs are extracted at git push time, not event arrival

   • Enables flexible matching when pushes arrive out-of-order
   • Helper functions in helpers.rs handle ref extraction

4. Bidirectional Waiting: Either side can arrive first

   • Event-first: Event waits for git push
   • Git-first: Placeholder created, waits for event

5. Automatic Expiry: 30-minute default expiry, extensible during processing

   • Background cleanup task runs every 60 seconds
   • Removes expired entries from all stores
   • Defers matching expiry while a concrete background Git sync is actively running; queued/backoff work receives no extension

6. Pressure-aware Background Git Fan-out: event-directed recovery begins with a one-second probe allowance of two remote Git passes per effective CPU

   • Healthy observation windows grow the allowance by 20% or one pass, whichever is greater, avoiding a lasting cap while giving the retrospective pressure signal time to reflect each preceding step
   • New CPU throttling or memory-high pressure reduces new admission to one pass while already-running work drains naturally
   • Linux services read their cgroup v2 constraints and pressure counters; other environments fall back to processor count and healthy-window growth
   • Existing per-domain limits remain responsible for being polite to each remote server
   • The probe and pressure gate prevent a cold sync spanning many domains from spawning enough Git processes to starve this relay's HTTP and WebSocket service
   • Foreground Git requests do not draw from this background-only limit

Data Types

See types.rs for complete definitions:

• RefPair: Ref name + object SHA pair
• AnnouncementPurgatoryEntry: Announcement with bare repo path, relays, and expiry
• StatePurgatoryEntry: State event with metadata
• PrPurgatoryEntry: PR event or placeholder with metadata

Integration Points

Write Policy (src/nostr/policy/):

• Announcement policy routes new announcements to purgatory; replacements accepted immediately
• State policy checks git data existence before adding to purgatory; checks purgatory announcements for authorization
• PR policy checks for placeholders before adding to purgatory
• Events return "purgatory: will not be served until git data arrives" message

Git Handlers (src/git/handlers.rs):

• On git push: Promote announcement from purgatory to database if present
• On git push: Check purgatory for matching state events
• On refs/nostr/* push: Check purgatory for PR events or create placeholders
• Release events from purgatory when git data arrives
• Save released events to database

Main.rs (src/main.rs):

• Creates Arc<Purgatory> at startup
• Passes purgatory to both write policy and git handlers
• Passes RepositoryLifecycle directly to HTTP git serving and deletion/recovery
• Spawns background cleanup task (60-second interval)

Thread Safety

• Uses Arc<DashMap> for lock-free concurrent access
• Safe to share between HTTP handlers, WebSocket handlers, and background tasks
• No blocking locks in hot paths

6. Configuration (src/config.rs)

pub struct Config {
    pub domain: String,
    pub owner_npub: String,
    pub relay_name: String,
    pub relay_description: String,
    pub git_data_path: PathBuf,
    pub relay_data_path: PathBuf,
    pub bind_address: SocketAddr,
    pub database_backend: DatabaseBackend,
}

pub enum DatabaseBackend {
    Lmdb,    // Default, production use
    NostrDb, // Alternative
    Memory,  // Testing
}

Configuration is loaded via clap CLI > environment variables > .env > defaults.

Data Flow

Push Operation Flow

1. Git Client → POST /<npub>/<id>.git/git-receive-pack
                ↓
2. HttpService routes to git::handlers::handle_receive_pack()
                ↓
3. Parse ref updates from request body (pkt-line format)
                ↓
4. Extract npub and identifier from URL
                ↓
5. authorization::get_authorization_for_owner()
   ├─ Query database for announcements
   ├─ Build recursive maintainer set
   └─ Get latest authorized state
                ↓
6. authorization::validate_push_refs()
   ├─ Check each ref matches state
   └─ Validate refs/nostr/ pushes
                ↓
7. If VALID:
   ├─ Spawn git-receive-pack subprocess
   ├─ Stream request body to git stdin
   └─ Stream git stdout back to client
                ↓
8. If INVALID:
   └─ Return HTTP 403 with error message

Repository Announcement Flow

1. Nostr Client → EVENT (Kind 30617)
                ↓
2. Nostr relay receives event
                ↓
3. Nip34WritePolicy::admit_event()
   ├─ Check if instance in clone tags
   ├─ Check if instance in relays tags
   ├─ OR: Check if recursive maintainer
   └─ Accept or reject
                ↓
4. If ACCEPTED:
   ├─ Is there an active announcement for (pubkey, identifier) in DB?
   │  ├─ YES → Accept immediately (replacement, repo already proven)
   │  └─ NO  → Route to announcement purgatory
                ↓
5. Announcement Purgatory path:
   ├─ Bare Git repository created immediately at
   │  <git_data_path>/<npub>/<identifier>.git
   ├─ Announcement held in purgatory (not served to clients)
   └─ Awaiting git data to prove content exists
                ↓
6. When git data arrives (push or background sync):
   ├─ Announcement promoted from purgatory to database
   ├─ Event now served to clients
   └─ SyncManager upgrades to Full sync level
                ↓
7. If no git data within 30 minutes:
   ├─ Bare repo deleted (soft expiry)
   ├─ Event retained 24h for potential revival
   └─ Eventually discarded if no git data arrives

State Event Flow

1. Nostr Client → EVENT (Kind 30618)
                ↓
2. Nostr relay receives event
                ↓
3. Nip34WritePolicy::admit_event()
   ├─ Check author is in maintainer set (DB + purgatory announcements)
   ├─ Validate state structure
   └─ Accept or reject
                ↓
4. If ACCEPTED:
   ├─ Does git data already exist for this state?
   │  ├─ YES → Save to database immediately
   │  └─ NO  → Add to state purgatory
                ↓
5. State Purgatory path:
   ├─ Event held in purgatory (not served to clients)
   ├─ Enqueued for background git data sync (3 min delay)
   └─ Awaiting git push or background sync
                ↓
6. When git push arrives:
   ├─ Authorization checks both database AND purgatory
   ├─ If authorized via purgatory state: push proceeds
   ├─ After successful push: state event saved to database
   └─ Removed from purgatory

Testing Strategy

See test-strategy.md for comprehensive testing documentation.

Quick Overview

Integration Tests (tests/):

• Use TestRelay fixture for automatic relay lifecycle
• Each test file in tests/ covers a GRASP-01 requirement

Audit Tests (grasp-audit/):

• Reusable compliance testing for any GRASP implementation
• Spec-mirrored structure in grasp-audit/src/specs/grasp01/

// Example: tests/nip01_compliance.rs
#[tokio::test]
async fn test_nip01_websocket_connection() {
    let relay = TestRelay::start().await;
    // Test NIP-01 compliance...
    relay.stop().await;
}

Performance Considerations

1. Async All The Way

• Use tokio for all I/O
• Non-blocking Git subprocess spawning via GitSubprocess
• Stream large pack files without buffering

2. Shared Database

• Single database instance shared between relay and Git handlers
• Direct queries for push authorization (no WebSocket round-trip)

3. Write Policy Caching

• Maintainer sets computed once per event validation
• State lookups use database indexes

Proactive Sync (GRASP-02)

The ngit-grasp relay implements Proactive Sync of Nostr Events, which synchronizes repository data from external relays listed in 30617 repository announcements. This enables the relay to maintain complete repository graphs even when events are published to other listed relays.

Key Features:

• Self-subscription discovery - monitors own relay for announcements and root events to follow, attached in-process to the embedded relay rather than dialling the public listener (works identically under GRASP-08 private mode, whose auth gate would refuse a self-dial)
• Three-way diff (compute_actions) determines new subscriptions needed
• Smart reconnection - uses since filter for quick reconnects (<15 min), fresh sync otherwise
• Health tracking with exponential backoff for failing relays
• Bounded connection workers keep slow DNS and websocket handshakes out of the sync actor while limiting network pressure to eight concurrent attempts
• Daily sync with random 23-25h timer to detect state drift
• Filter consolidation when incremental fragmentation exceeds the desired live-filter baseline by 70; rebuilds are deferred until in-flight batches drain so EOSE and purgatory work remain responsive
• Rejected events index - prevents wasteful broad re-fetching while retaining exact IDs for dependency recovery
• Desired-source retention keeps listed GRASP-02 relays retryable until repository work is actually confirmed, including StateOnly invitation sync
• Bounded recursive related-event coverage turns accepted descendants into the next remote query frontier through event and address references, with an eight-generation traversal and a configurable soft limit, defaulting to 500, for each subtree rooted at an event which directly tags a repository root. The local database deterministically reconstructs saturated branches after restart; relay connections retain independent progress and require no shared admission coordinator

Architecture:

┌─────────────────────────────────────────────────────────────┐
│                       SyncManager                            │
├─────────────────────────────────────────────────────────────┤
│                                                             │
│  ┌──────────────────┐              ┌──────────────────┐    │
│  │  SelfSubscriber  │──actions──▶  │  Main Event Loop │    │
│  │  (own relay)     │              │  (Arc<Mutex>)    │    │
│  └──────────────────┘              └────────┬─────────┘    │
│                                             │              │
│  ┌──────────────────┐              ┌────────▼─────────┐    │
│  │  Daily Timer     │──────────────▶  RelayConnection │    │
│  │  (23-25h random) │              │  per external    │    │
│  └──────────────────┘              │  relay           │    │
│                                    └──────────────────┘    │
│  ┌──────────────────┐                                      │
│  │  Health Tracker  │  Exponential backoff, dead detection │
│  │  (DashMap)       │                                      │
│  └──────────────────┘                                      │
│  ┌──────────────────────────────────────────────────────┐  │
│  │  Rejected Events Index (Two-Tier)                   │  │
│  │  ┌────────────────┐    ┌──────────────────────┐    │  │
│  │  │  Hot Cache     │    │  Cold Index          │    │  │
│  │  │  (2 min)       │    │  (7 days)            │    │  │
│  │  │  Full events   │    │  IDs + metadata      │    │  │
│  │  └────────────────┘    └──────────────────────┘    │  │
│  └──────────────────────────────────────────────────────┘  │
└─────────────────────────────────────────────────────────────┘

Source Code: src/sync/

For full design details, see grasp-02-proactive-sync.md.

GRASP-03 Sync+ is a default-on mailbox-discovery overlay on this manager. Set NGIT_SYNC_PLUS_ENABLED=false to retain GRASP-02 sync without discovering accepted root and descendant participants' NIP-65 read/write mailboxes; NIP-11 advertises GRASP-03 only while the overlay is enabled. Exact thread provenance scopes each mailbox to its accepted roots. Accepted root authors' read/unmarked inboxes retain ordinary live/rotating GRASP-02 coverage. Wider participant mailboxes use independent, history-only fetch_events workers: at most one per relay and one new start per maintenance pass. They reuse the connection's ordinary pacing, subscription ledger, pagination and 30-second per-page terminal timeout without installing permanent participant subscriptions or coupling progress between relays.

Rejected Events Index

The rejected events index solves two critical problems during sync:

1. Negentropy sync efficiency: Prevents repeatedly downloading events that will be rejected again
2. Race condition resolution: Enables immediate hot-cache re-processing or an exact-ID fetch after the full event expires

Bounded Architecture:

Tier	Duration	Storage	Purpose
Hot Cache	2 minutes	Full events	Immediate re-processing when dependencies arrive
Cold Index	7 days	Metadata only	Prevent re-fetch during negentropy sync
Related Dependency Index	7 days	Full events + reference keys + relay hints	Retry policy orphans when either side of their relationship is accepted

Event Flow:

Event Rejected (e.g., maintainer before owner announcement)
    │
    ├──▶ Store full event in Hot Cache (2 min expiry)
    └──▶ Store metadata in Cold Index (7 day expiry)
    
Reciprocal Invitation Arrives (owner announcement enters purgatory)
    │
    ├──▶ Keep dependency-resolvable IDs in Cold Index
    ├──▶ Re-process from Hot Cache when the full event remains available
    └──▶ Otherwise fetch only the retained IDs from the maintainer relay chain

Exact-ID Recovery
    │
    ├──▶ Connect to relay hints before starting recovery
    ├──▶ Query all connected maintainer-chain relays in parallel
    ├──▶ Process announcements before dependent state events
    └──▶ Remove IDs only after policy processing succeeds

Negentropy Sync
    │
    └──▶ Exclude Cold Index IDs from "missing events" calculation

Related Event Rejected as an Orphan
    │
    ├──▶ Retain the full event in the crash-safe checkpoint
    ├──▶ Match later accepted IDs and addresses in both directions
    ├──▶ Re-process an iterative closure of newly unblocked events
    └──▶ Keep retryable results pending; remove terminal outcomes

Exact-ID recovery runs as bounded background work, so a slow relay does not hold the main sync-manager lock. Failed or empty requests retain their IDs and are retried no more than once every 30 seconds. Each relay request has a five-second timeout.

Tracked Events:

• Repository announcements (kind 30617) rejected for not listing this service or a dependency-resolvable maintainer validation failure
• State events (kind 30618) rejected for missing announcements or dependency-resolvable authorization failures
• Permanently invalid events classified as Other remain excluded and are not exact-refetched
• Related comments, reactions, zap requests, and other policy orphans are retained under fixed limits: 1,024 entries, 8 MiB total, 128 KiB per event, and 512 attempts per triggered closure

Source Code: src/sync/rejected_index.rs

Contributor PR Submission (GRASP-06)

Optional endpoint at /prs/<npub>/<identifier>.git, gated on NGIT_GRASP06_ENABLE (default off). Contributors push refs/nostr/<event-id> for PR and PR Update events targeting any repository — even repos this relay has no accepted announcement for. The endpoint is unauthenticated at the HTTP level; validity is established by the signed PR / PR Update event and inline acceptance rules.

Module layout:

• src/grasp06/endpoint.rs — URL parsing.
• src/grasp06/paths.rs — on-disk path conventions under <git_data_path>/prs/<hex>/<identifier>.git.
• src/grasp06/fetch.rs — empty-repo synthesis for info/refs and git-upload-pack against repos that don't yet exist on disk.
• src/grasp06/receive.rs — git-receive-pack with init-on-push, strict refs/nostr/<event-id> ref-name validation, and per-ref post-push validation against the database and purgatory. Uses a per-(submitter, identifier) PrsPathState (mutex + in_flight counter) so concurrent pushes to the same path proceed in parallel: the mutex is held only for init+register and decrement+end-of-push cleanup, not across git-receive-pack itself. The same state is consulted (with try_lock in synchronous contexts) by the PR-event policy and the purgatory expiry sweep, which only remove a /prs/ ref or zero-ref bare repo when in_flight == 0.
• src/grasp06/policy.rs — strict clone-tag URL comparator used by the PR-event acceptance relaxation.
• src/grasp06/cleanup.rs — one-shot startup scan over <git_data_path>/prs/ that removes zero-ref bare repos left behind by a previous run (crash mid-push, crash mid-cleanup, or shutdown with unresolved scoped placeholders). Runs before the HTTP server starts accepting requests; no locking is needed because nothing else is touching /prs/ yet.

/prs/ repos are intentionally isolated from other subsystems: empty-repo cleanup skips the /prs/ subtree, the proactive-sync subsystem never discovers them because subscriptions are built from DB-resident announcements, and the standard repo landing page guards against ever matching a /prs/ path. Full design: GRASP-06 Contributor Pull Request Submission. Operator how-to: Enable GRASP-06.

Private Service Authentication (GRASP-08)

Private mode is an optional access layer around the normal GRASP runtime. A single PrivateAccess set is shared by the HTTP and WebSocket services and the announcement admission policy. Push authorization remains the GRASP-01 policy; a private credential proves service membership but never grants push rights. The effective set combines operator-configured members with NIP-11 owner pubkeys learned for relays referenced by accepted announcements, provided those relays' NIP-11 also advertises GRASP-08 (a public relay's owner gains nothing legitimate from private membership). Purgatory-only announcements are excluded. Reconciliation reuses the accepted repository index and the NIP-11 fetch already performed once per connection session, so private mode adds neither outbound connections nor subscriptions.

Because accepted announcements drive membership, announcement admission is itself membership-gated in private mode: a kind-30617 event is only admitted when its author is a current effective member at admission time, on every arrival path (direct publish, sync import, purgatory promotion). Non-member announcements are rejected through the normal announcement rejection machinery. State events (kind 30618) keep the GRASP-01 maintainer rules, and removal is non-retroactive — repositories admitted while their author was a member remain hosted until the operator curates them.

For Nostr, Hyper completes the public WebSocket upgrade and a message-level proxy sends and validates NIP-42 authentication before a connection reaches LocalRelay. Missing authentication uses the auth-required: prefix and a valid authentication by a nonmember uses restricted:. Once authenticated, the proxy bridges messages through an in-memory WebSocket pair to LocalRelay. Keeping the access check outside nostr-relay-builder is necessary because its query and write policies do not receive the authenticated session pubkey.

For Git, authentication runs before repository existence checks or request body collection. The signed NIP-98 event names the canonical repository root and method GET; that credential is reusable for GET, HEAD, and POST requests to the repository root and Smart HTTP subpaths for its 60-second validity window. Payload tags and replay protection are intentionally not applied. Every authentication failure is the same empty 401 Unauthorized response, preventing unauthenticated repository enumeration.

Private mode advertises GRASP-08 plus NIP-42 and NIP-98 in NIP-11. It is incompatible with GRASP-06 because that extension deliberately exposes an unauthenticated contributor write surface. It also suppresses relay-owner identity publication: the kind 0/10002 events are seeded and served locally but never sent to the configured user-index relays, so a private relay does not advertise its existence.

Outbound, every sync connection (public or private instance) answers NIP-42 challenges with the relay owner key when available; a restricted: refusal after authentication parks the subscription via the existing policy-refusal machinery. Peers advertising GRASP-08 in NIP-11 split by our own mode: a public instance detects them with a pre-dial NIP-11 fetch and parks them without ever opening the WebSocket, while a private instance treats them as peers — NIP-42 on the WebSocket plus the GRASP-08 repository-root NIP-98 credential on purgatory Git fetches from that peer's host, both signed with the relay owner key. Relays without a readable supported_grasps are ordinary sync targets. See GRASP-08 design.

One process currently represents one private collaborator service. Operators can run several independently configured instances for different groups. Fleet provisioning and lifecycle automation are deliberately left to a later change; they are deployment conveniences rather than part of the authentication boundary implemented here.

Future Extensions

GRASP-02: Proactive Sync

GRASP-02 is only partially implemented. still outstanding is the proactive sync of git data for 1. state event and 2. PRs / PR Update refs.

GRASP-05: Archive

Relax the write policy to accept all repository announcements regardless of clone/relays tags.

Deployment

Single Binary

cargo build --release
NGIT_RELAY_OWNER_NSEC=nsec1... \
  ./target/release/ngit-grasp --domain example.com

Docker

FROM rust:1.75 as builder
WORKDIR /app
COPY . .
RUN cargo build --release

FROM debian:bookworm-slim
RUN apt-get update && apt-get install -y git && rm -rf /var/lib/apt/lists/*
COPY --from=builder /app/target/release/ngit-grasp /usr/local/bin/
EXPOSE 7334
CMD ["ngit-grasp"]

Systemd

[Unit]
Description=ngit-grasp GRASP server
After=network.target

[Service]
Type=simple
User=git
WorkingDirectory=/opt/ngit-grasp
EnvironmentFile=/opt/ngit-grasp/.env
ExecStart=/usr/local/bin/ngit-grasp
Restart=on-failure

[Install]
WantedBy=multi-user.target

Security Considerations

1. Input Validation: All npub/identifier inputs must be validated
2. Path Traversal: Prevent directory traversal in repository paths
3. DoS Protection: Rate limiting on both HTTP and WebSocket
4. Resource Limits: Limit pack file sizes, event sizes
5. Nostr Event Validation: Strict signature verification (handled by nostr-relay-builder)

Conclusion

ngit-grasp uses inline authorization at the HTTP handler level, giving full control over request handling, WebSocket upgrades, and CORS headers while maintaining full GRASP-01 compliance. The purgatory system ensures that only repositories with actual git content are served to clients, and that events and git data are always consistent when released to the database.

Related Documentation

• Inline Authorization Explanation - Why we chose this approach
• GRASP-02 Proactive Sync Design - Current production sync implementation
• Test Strategy - Comprehensive testing documentation
• GRASP-01 Implementation Learnings - Patterns and lessons learned