solid-pod-rs-activitypub

Status: 0.4.0-alpha.2 — functional ActivityPub federation crate.

Rust port of the JSS ActivityPub surface (JavaScriptSolidServer/src/ap/*). 4,453 LOC across 9 modules; 53 tests. Integrators may take a dependency today.

What ships

Module	Responsibility
`actor`	Actor document rendering + `negotiate_actor_format()` (Accept-negotiation between `application/activity+json` and LDP profiles).
`inbox`	`POST /inbox` handling with HTTP Signature verification (draft-cavage-http-signatures v12).
`outbox`	`handle_outbox()` (pre-formed activities) + `handle_outbox_post()` (raw Notes auto-wrapped in `Create`). Follower fan-out delivery.
`delivery`	HTTP Signature signing, SHA-256 digest headers, exponential retry, `enqueue_to_inboxes()` batch helper.
`http_sig`	`HttpSignatureVerifier` + `HttpActorKeyResolver` implementing draft-cavage v12 over RSA-SHA256.
`store`	SQLite-backed follower/following/outbox/delivery-queue persistence. Actor cache with 24-hour freshness.
`error`	Typed error hierarchy (`InboxError`, `OutboxError`, `DeliveryError`, `StoreError`).
`webfinger`	AP-specific WebFinger JRD rendering.
`nodeinfo`	NodeInfo 2.1 document emission.

Federation flow

sequenceDiagram
    participant Author as Author (Local)
    participant Outbox as Outbox Handler
    participant Store as SQLite Store
    participant DQ as Delivery Queue
    participant Remote as Remote Inbox

    Author->>Outbox: POST /outbox
    Note over Outbox: Raw Note or Content-only body?
    Note over Outbox: Auto-wrap in Create activity

    Outbox->>Outbox: Stamp UUID id + actor + published
    Outbox->>Store: record_outbox(activity)
    Store-->>Outbox: activity_id

    Outbox->>Store: follower_inboxes(actor)
    Store-->>Outbox: [inbox_a, inbox_b, ...]

    loop Each follower inbox
        Outbox->>DQ: enqueue_delivery(id, inbox)
    end

    Outbox-->>Author: 201 Created + OutboundDelivery

    Note over DQ: Async delivery with retry

    loop Delivery worker
        DQ->>DQ: Sign request (HTTP Sig draft-cavage v12)
        DQ->>DQ: SHA-256 Digest header
        DQ->>Remote: POST /inbox (signed)
        alt 2xx
            DQ->>Store: mark delivered
        else 5xx
            DQ->>DQ: Exponential backoff retry
        else 4xx
            DQ->>Store: mark failed (no retry)
        end
    end

flowchart LR
    REQ["Inbound request<br/>Accept header"] --> NEG{"negotiate_actor_format()"}
    NEG -->|"activity+json<br/>ld+json (profile=activitystreams)"| AJ["ActivityJson<br/>AP Actor document"]
    NEG -->|"text/turtle<br/>application/n-triples<br/>*/*"| LDP["LdpProfile<br/>WebID profile doc"]

    style REQ fill:#4a90d9,stroke:#2c5f8a,color:#fff
    style AJ fill:#e67e22,stroke:#bf6516,color:#fff
    style LDP fill:#2ecc71,stroke:#1a9850,color:#fff

Parity rows

Rows closed by this crate (see ../solid-pod-rs/PARITY-CHECKLIST.md):

102 — ActivityPub Actor discovery.
103 — inbox with HTTP Signature verification.
104 — outbox emission.
105 — Follow / Accept / Undo handling.
106 — Create activity delivery.
107 — Follower + Following collections.
108 — ActivityPub conformance subset.
131 — NodeInfo 2.0 (AP-specific fields).

Sprint 12 additions (JSS v0.0.60–v0.0.71 delta):

169 — Outbox POST with Note→Create wrapping.
170 — Accept-negotiation for actor profiles.
171 — Actor cache with freshness check.
172 — enqueue_to_inboxes() batch delivery.

Sprint 12 changes

handle_outbox_post() — accepts Note, pre-formed Activity, or content-only body. Notes are auto-wrapped in Create with UUID IDs and ISO 8601 timestamps. Matches JSS v0.0.67 outbox behaviour.
negotiate_actor_format(accept: &str) — returns ActorFormat::ActivityJson or ActorFormat::LdpProfile based on the request Accept header.
Store::cache_actor() / get_cached_actor() / is_actor_cache_fresh() — 24-hour chrono-based freshness window.
enqueue_to_inboxes() — batch delivery helper.
User-Agent updated to solid-pod-rs-activitypub/0.4.0.

JSS references

src/ap/index.js
src/ap/routes/inbox.js
src/ap/routes/outbox.js
src/ap/store.js
src/ap/keys.js

Licence

AGPL-3.0-only.