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atproto made easy crates.io/crates/jacquard
atproto rust
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> Simple and powerful AT Protocol (Bluesky) client library emphasizing spec compliance, flexible string backing types, and minimal boilerplate.
## Core philosophy
**Flexible string backing, zero-copy when you want it.** All API types are parameterised on `S: BosStr = DefaultStr` (where `DefaultStr = SmolStr`). By default, types use `SmolStr` for inline storage of short strings and `Arc<str>` for longer ones. When zero-copy is needed, use `CowStr<'_>` or `&str` as the backing type. `DeserializeOwned` works out of the box for `SmolStr`-backed types.
**Validated types everywhere.** DIDs, handles, AT-URIs, NSIDs, TIDs, CIDs -- all have strongly-typed, validated wrappers. Invalid inputs fail at construction time, not deep in your application logic.
**Batteries included, but replaceable.** High-level `Agent` for convenience, or use stateless `XrpcCall` builder for full control. Mix and match as needed.
---
## Critical patterns to internalize
### String backing types
All validated types (Did, Handle, AtUri, Nsid, etc.) and all generated API types are generic over `S: BosStr`:
```rustpub struct Did<S: BosStr = DefaultStr> { /* ... */ }pub struct Post<S: BosStr = DefaultStr> { /* ... */ }```
The `BosStr` trait combines `Bos<str> + AsRef<str> + FromStaticStr`. Types that implement it:
| Type | Allocates? | Use case ||------|-----------|----------|| `SmolStr` (default) | Inline <=23 bytes, Arc for longer | General-purpose owned strings || `&str` | Never | Zero-copy borrowed access || `CowStr<'a>` | Only when owned variant needed | Borrow-or-own flexibility || `String` | Always on heap | Standard owned strings |
**Rule**: Use default `SmolStr` for most code. Use `CowStr<'_>` or `&str` when zero-copy parsing matters. Use `String` when interfacing with APIs that require it.
### String type constructors
ALL validated string types (Did, Handle, AtUri, Nsid, etc.) follow this pattern:
```rust// Wraps S directly (validates). S defaults to SmolStr.let did = Did::new(SmolStr::new("did:plc:abc123"))?;
// Zero-allocation for static strings.let nsid = Nsid::new_static("com.atproto.repo.getRecord")?;
// Validates and produces owned (SmolStr-backed by default).let owned = Did::new_owned("did:plc:abc123")?;
// Cheap borrow: Did<SmolStr> -> Did<&str>.let borrowed: Did<&str> = owned.borrow();
// Cross-type conversion: Did<SmolStr> -> Did<String>.let string_did: Did<String> = owned.convert();
// FromStr always allocates into SmolStr.let did: Did = "did:plc:abc123".parse()?;
// AVOID: Roundtripping through String.let s = did.as_str().to_string();let did2 = Did::new_owned(&s)?; // Pointless allocation.```
**Rule**: Use `new_static()` for string literals, `new_owned()` when validating from `&str`, `borrow()` for cheap temporary access, `convert()` for cross-type conversion.
### Response parsing: choose your backing type
XRPC responses wrap a `Bytes` buffer. You choose how to deserialize:
```rustlet response = agent.send(request).await?;
// Option 1: Owned SmolStr-backed (DeserializeOwned -- just works!)let output: GetPostOutput = response.into_output()?;// Can return from functions, store anywhere, no lifetime concerns.
// Option 2: Zero-copy with CowStr (borrows from response buffer)let output: GetPostOutput<CowStr<'_>> = response.parse()?;// output borrows from response, both must stay in scope.
// Option 3: Zero-copy with &str (borrows from response buffer)let output: GetPostOutput<&str> = response.parse()?;// Cheapest, but output borrows from response.```
**Rule**: Use `.into_output()` for most code -- it returns `SmolStr`-backed owned types with no lifetime concerns. Use `.parse::<CowStr<'_>>()` or `.parse::<&str>()` when zero-copy performance is critical and you can keep the response alive.
### Type system: GATs parameterised on S
Jacquard uses **Generic Associated Types** on `XrpcResp` parameterised on backing string type:
```rusttrait XrpcResp { type Output<S: BosStr>; // GAT parameterised on S, not lifetime. type Err: Error + DeserializeOwned; // Always owned, always SmolStr-backed.}```
**Why this matters**: `SmolStr`-backed types implement `DeserializeOwned`, so `.into_output()` just works. For zero-copy, callers pass `CowStr<'_>` or `&str` as `S` via `.parse()`. Error types are always owned since they are uncommon and don't need zero-copy.
**When implementing custom types**: Parameterise on `S: BosStr`, not on lifetimes. Use `#[serde(bound(deserialize = "S: Deserialize<'de> + BosStr"))]`.
### Backing type conversion
```rust// borrow() -- cheap Did<SmolStr> -> Did<&str>let borrowed: Did<&str> = my_did.borrow();
// convert() -- type-level conversion (e.g., SmolStr -> String)let string_did: Did<String> = my_did.convert();
// IntoStatic -- converts CowStr<'_> -> SmolStr (or other owned)use jacquard::common::IntoStatic;let owned: Post = borrowed_post.into_static();
// as_str() -- get &str from any concrete S (e.g., SmolStr)let s: &str = my_did.as_str();
// as_ref() -- get &str from generic S (via AsRef<str>)fn generic<S: BosStr>(did: &Did<S>) -> &str { did.as_ref()}```
**Rule**: Use `.borrow()` for cheap `Type<&str>` access. Use `.convert()` for cross-type conversion. Use `.into_static()` when converting from borrowed (`CowStr<'_>`) to owned. Use `.as_str()` for concrete types, `.as_ref()` for generic `S`.
---
## Crate-by-crate guide
### jacquard (main crate)
**Primary entry point**: `Agent<A: AgentSession>`
```rustuse jacquard::client::{Agent, CredentialSession, MemorySessionStore};use jacquard::identity::PublicResolver;
// App password auth.let (session, _info) = CredentialSession::authenticated( "alice.bsky.social".into(), "app-password".into(), None, // session_id).await?;let agent = Agent::from(session);
// Make typed XRPC calls.use jacquard::api::app_bsky::feed::get_timeline::GetTimeline;let response = agent.send(&GetTimeline::<&str>::new().limit(50).build()).await?;let timeline = response.into_output()?;```
**Auto-refresh**: Both `CredentialSession` and `OAuthSession` automatically refresh tokens on 401/expired errors. One retry per request.
**Typed record operations** (via `AgentSessionExt` trait):
```rustuse jacquard::api::app_bsky::feed::post::Post;
// Create.let post = Post::builder() .text("Hello ATProto!") .created_at(Datetime::now()) .build();agent.create_record::<Post, _>(post, None).await?;
// Get (type-safe!).let uri = Post::uri("at://did:plc:abc/app.bsky.feed.post/123")?;let response = agent.get_record::<Post>(&uri).await?;let post_output = response.into_output()?;
// Update with fetch-modify-put pattern.agent.update_record::<Profile>(&uri, |profile| { profile.display_name = Some(SmolStr::new("New Name"));}).await?;```
**Key traits**:- `AgentSession`: Common interface for both auth types- `XrpcClient`: Stateful XRPC (has base URI, auth tokens)- `HttpClient`: Low-level HTTP abstraction
**Common mistake**: Forgetting that `SmolStr`-backed types are already owned. You do not need to call `.into_static()` on types returned from `.into_output()`. The `.into_static()` method is only needed when converting from `CowStr<'_>`-backed or `&str`-backed types to owned.
### jacquard-common (foundation)
**Core types**: `Did<S>`, `Handle<S>`, `AtUri<S>`, `Nsid<S>`, `Tid`, `Cid<S>`, `CowStr<'a>`, `SmolStr`, `Data<S>`, `RawData<'a>`
**String type traits** (ALL validated types implement these):- `new(S)` - Validates, wraps S directly- `new_static(&'static str)` - Validates, zero alloc- `new_owned(impl AsRef<str>)` - Validates, produces owned S- `borrow(&self) -> Type<&str>` - Cheap borrowed view- `convert<B: BosStr + From<S>>(self) -> Type<B>` - Cross-type conversion- `raw(&str)` - Panics on invalid (use when you KNOW it's valid)- `unchecked(&str)` - Unsafe, no validation- `as_str(&self) -> &str` - Get string reference- `Display`, `FromStr`, `Serialize`, `Deserialize`, `IntoStatic`
**SmolStr**: The default backing type. Inline storage for strings <=23 bytes (covers most handles, DIDs, rkeys). Longer strings use `Arc<str>` for O(1) clone. Implements `DeserializeOwned`.
**CowStr<'a>**: Borrow-or-own string. Uses `SmolStr` for owned variant. This type still uses lifetimes -- it is the borrow-or-own primitive.
**XRPC layer**:
```rust// Stateless XRPC (with any HttpClient).use jacquard::common::xrpc::XrpcExt;let http = reqwest::Client::new();let response = http .xrpc(Uri::parse("https://bsky.social").map_err(|(e, _)| e)?) .auth(AuthorizationToken::Bearer(token)) .proxy(did) .send(&request) .await?;
// Stateful XRPC (implement XrpcClient trait).let response = agent.send(request).await?;```
**Data<S> vs RawData<'a>**:- `Data<S>`: Validated, type-inferred atproto values (strings parsed to Did/Handle/etc.), parameterised on `S: BosStr`- `RawData<'a>`: Minimal validation, lifetime-based (intentionally stays lifetime-based), suitable for pass-through/relay use cases
```rust// Convert typed -> untyped -> typed.let post = Post::builder().text("test").build();let data: Data = to_data(&post)?;let post2: Post = from_data(&data)?;
// NEVER use serde_json::Value.// let value: serde_json::Value = ...;// let data: Data = ...;```
**Streaming** (feature: `streaming`):- `ByteStream` / `ByteSink`: Platform-agnostic (works on WASM via `n0-future`)- `HttpClientExt::send_http_streaming()`: Stream response- `HttpClientExt::send_http_bidirectional()`: Stream both request and response
**WebSocket** (feature: `websocket`):- `WebSocketClient` trait, `WebSocketConnection`- Native + WASM: tokio-tungstenite-wasm
**Collection trait** (for record types):
```rustpub trait Collection { const NSID: &'static str; type Record: XrpcResp; // Marker type for get_record().}
// Enables typed record retrieval:let response: Response<Post::Record> = agent.get_record(did, rkey).await?;```
**CallOptions<'a>**: Still uses lifetimes (not parameterised on S). This is intentional for the options builder pattern.
### jacquard-api (generated bindings)
**764 lexicon schemas** across 52+ namespaces.
**Feature organization**:- `minimal`: Core atproto only- `bluesky`: Bluesky app + chat + ozone- `other`: Curated third-party lexicons- `lexicon_community`: Community extensions- `ufos`: Experimental/niche
**Generated patterns**:- All types: `Foo<S: BosStr = DefaultStr>` with `#[serde(bound(deserialize = "S: Deserialize<'de> + BosStr"))]`- All implement `IntoStatic`, `Serialize`, `Deserialize`, `Clone`, `PartialEq`, `Eq`- Builders on types with 2+ fields (some required)- Open unions: `Unknown(Data<S>)` variant via `#[open_union]` macro- Objects: `extra_data: BTreeMap<SmolStr, Data<S>>` via `#[lexicon]` macro- Known-values enums: `Other(S)` catch-all
**Union collision detection**: When multiple namespaces define similar types, foreign refs get prefixed:```rust// If both app.bsky.embed.images and sh.custom.embed.images exist:pub enum SomeUnion<S: BosStr = DefaultStr> { BskyImages(Box<app_bsky::embed::images::View<S>>), CustomImages(Box<sh_custom::embed::images::View<S>>),}```
**For each collection (record type)**, generated code includes:1. Main record struct (e.g., `Post<S: BosStr = DefaultStr>`)2. `GetRecordOutput` wrapper (`PostGetRecordOutput<S>` with uri, cid, value)3. Marker struct (`PostRecord`) implementing `XrpcResp`4. `Collection` trait impl5. Helper: `Post::uri()` for constructing typed URIs
**For each XRPC endpoint**:1. Request struct with builder2. Output struct3. Error enum (open union, includes `Unknown` variant)4. Response marker implementing `XrpcResp`5. Request marker implementing `XrpcRequest`6. Endpoint marker implementing `XrpcEndpoint` (server-side)
**Common mistakes**:- Not handling `Unknown` variant in union matches (non-exhaustive!)- Forgetting that when not using the builder pattern, or Default construction, you must supply `extra_data: BTreeMap::new()` in the constructor, in addition to explicitly named fields- Calling `.into_static()` in tight loops (it is a no-op for SmolStr, but is unnecessary)
### jacquard-derive (macros)
**`#[lexicon]`**: Adds `extra_data` field to capture unknown fields during deserialization.
```rust#[lexicon]#[derive(Serialize, Deserialize)]struct MyType<S: BosStr = DefaultStr> { known_field: S, // Macro adds: pub extra_data: BTreeMap<SmolStr, Data<S>>}```
**`#[open_union]`**: Adds `Unknown(Data<S>)` variant to enums.
```rust#[open_union]#[serde(tag = "$type")]enum MyUnion<S: BosStr = DefaultStr> { KnownVariant(Foo<S>), // Macro adds: #[serde(untagged)] Unknown(Data<S>)}```
**`#[derive(IntoStatic)]`**: Generates conversion from any `S` to `SmolStr`-backed types.
```rust#[derive(IntoStatic)]struct Post<S: BosStr = DefaultStr> { text: S, likes: u32,}
// Generates conversion so Post<CowStr<'_>> -> Post<SmolStr>, etc.```
**`#[derive(XrpcRequest)]`**: Generates XRPC boilerplate for custom endpoints.
```rust#[derive(Serialize, Deserialize, XrpcRequest)]#[xrpc( nsid = "com.example.getThing", method = Query, output = GetThingOutput, error = GetThingError, // Optional, defaults to GenericError. server // Optional, generates XrpcEndpoint marker.)]struct GetThing { pub id: SmolStr,}```
**Critical**: Custom types used as XRPC outputs must derive `IntoStatic` if they will be used with `.parse()` and then converted. For `.into_output()`, they just need `DeserializeOwned` (which `SmolStr`-backed types get for free).
### jacquard-oauth (OAuth/DPoP)
**Session types parameterised on S** for flexible backing storage.
**OAuth flow**:
```rustuse jacquard::oauth::client::OAuthClient;use jacquard::client::FileAuthStore;
let oauth = OAuthClient::with_default_config( FileAuthStore::new("./auth.json"));
// Loopback flow (feature: loopback).let session = oauth.login_with_local_server( "alice.bsky.social", Default::default(), LoopbackConfig::default(),).await?;
let agent = Agent::from(session);```
**OAuthMetadata<S>**: Parameterised so callers can borrow from stored metadata.
**Nonce handling**: Automatic retry on `use_dpop_nonce` errors (400 for auth server, 401 for PDS). Max one retry per request.
**Token refresh**: Automatic on `invalid_token` errors. Uses `SessionRegistry` with per-DID+session_id locks to prevent concurrent refresh races.
**private_key_jwt**: For non-loopback clients. Automatically used if server supports it.
### jacquard-identity (identity resolution)
**Resolution chains** (configurable fallback order):
**Handle -> DID**:1. DNS TXT `_atproto.<handle>` (feature: `dns`, skipped on WASM)2. HTTPS `https://<handle>/.well-known/atproto-did`3. PDS XRPC `com.atproto.identity.resolveHandle`4. Public API fallback `https://public.api.bsky.app` (if enabled)5. Slingshot mini-doc (if configured)
**DID -> Document**:1. `did:web`: HTTPS `.well-known/did.json`2. `did:plc`: PLC directory or Slingshot3. PDS XRPC `com.atproto.identity.resolveDid`
**Methods are generic over backing type**:```rust// resolve_handle accepts any Handle<S> backing type.let did: Did = resolver.resolve_handle(&handle).await?;// Returns Did (= Did<SmolStr>) for owned results.
// resolve_did_doc same pattern.let response = resolver.resolve_did_doc(&did).await?;let doc = response.parse_validated()?; // Validates doc.id matches requested DID.
// Combined: get PDS endpoint.let pds_url = resolver.pds_for_did(&did).await?;```
**DidDocResponse pattern** (same as XRPC responses):
```rustlet response = resolver.resolve_did_doc(&did).await?;
// Borrow from buffer.let doc: DidDocument<CowStr<'_>> = response.parse()?;
// Validate doc ID.let doc = response.parse_validated()?; // Error if doc.id != requested DID.
// Convert to owned.let doc: DidDocument = response.into_owned()?;```
**Mini-doc fallback**: If full DID document parsing fails, automatically tries parsing as `MiniDoc` (Slingshot's minimal format) and synthesizes a minimal `DidDocument`. This is transparent to caller.
**OAuthResolver trait**: Auto-implemented for `JacquardResolver`. Adds OAuth metadata resolution:
```rust// High-level: accepts handle, DID, or HTTPS URL.let (server_metadata, doc_opt) = resolver.resolve_oauth("alice.bsky.social").await?;
// From identity (handle or DID).let (server_metadata, doc) = resolver.resolve_from_identity("alice.bsky.social").await?;
// From service URL (PDS or entryway).let server_metadata = resolver.resolve_from_service(&pds_url).await?;
// Verify issuer authority over DID.let pds = resolver.verify_issuer(&server_metadata, &sub_did).await?;```
### jacquard-axum (server-side)
**Note**: jacquard-axum is temporarily out of the workspace while the extractor is redesigned for the BosStr type system.
**ExtractXrpc**: Type-safe XRPC request extraction, parameterised on `S: BosStr`.
```rustuse jacquard_axum::{ExtractXrpc, IntoRouter};use jacquard::api::com_atproto::identity::resolve_handle::ResolveHandleRequest;use jacquard::common::DefaultStr;
async fn handle_resolve( ExtractXrpc(req): ExtractXrpc<ResolveHandleRequest, DefaultStr>) -> Json<ResolveHandleOutput> { let did = resolve_handle_logic(&req.handle).await; Json(ResolveHandleOutput { did, extra_data: Default::default() })}
// Automatic routing.let app = Router::new() .merge(ResolveHandleRequest::into_router(handle_resolve));```
**Query vs Procedure**:- Query (GET): Extracts from query string via `serde_html_form`- Procedure (POST): Calls `Request::decode_body()` (default: JSON, override for CBOR)
**Custom encodings**:
```rustimpl XrpcRequest for MyRequest { fn decode_body(body: &[u8]) -> Result<Box<Self>> { let req = serde_ipld_dagcbor::from_slice(body)?; Ok(Box::new(req)) }}```
**Service auth** (feature: `service-auth`):
```rustuse jacquard_axum::service_auth::{ServiceAuthConfig, ExtractServiceAuth};
let config = ServiceAuthConfig::new( Did::new_static("did:web:feedgen.example.com")?, resolver,);
async fn handler( ExtractServiceAuth(auth): ExtractServiceAuth,) -> String { format!("Authenticated as {}", auth.did())}
let app = Router::new() .route("/xrpc/app.bsky.feed.getFeedSkeleton", get(handler)) .with_state(config);```
**Method binding (`lxm` claim)**: Default enabled. Binds JWTs to specific XRPC methods to prevent token reuse across endpoints.
**JTI replay protection**: NOT built-in. You must implement:
```rustif let Some(jti) = auth.jti() { if state.seen_jtis.contains(jti) { return Err(StatusCode::UNAUTHORIZED); } state.seen_jtis.insert(jti.to_string(), auth.exp);}```
**Common mistakes**:- Forgetting the second type parameter on `ExtractXrpc<Request, S>` (defaults to `DefaultStr`)- Using wrong trait (use `XrpcEndpoint` marker, not `XrpcRequest`)- Not implementing JTI tracking (allows replay attacks)- Disabling method binding without understanding security implications
### jacquard-repo (repository primitives)
**MST (Merkle Search Tree)**: Immutable, persistent data structure.
```rustuse jacquard_repo::mst::Mst;use jacquard_repo::storage::MemoryBlockStore;
let storage = MemoryBlockStore::new();let mst = Mst::new(storage.clone());
// IMMUTABLE: Always reassign.let mst = mst.add("app.bsky.feed.post/abc", record_cid).await?;let mst = mst.add("app.bsky.feed.post/xyz", record_cid2).await?;
// Persist and get root CID.let root_cid = mst.persist().await?;```
**Key validation**: `[a-zA-Z0-9._:~-]+` with exactly one `/` separator. Max 256 bytes. Format: `collection/rkey`.
**Diff operations**:
```rustlet diff = old_mst.diff(&new_mst).await?;diff.validate_limits()?; // Enforce 200 op limit (protocol).
// Convert to different formats.let verified_ops = diff.to_verified_ops(); // For batch().let repo_ops = diff.to_repo_ops(); // For firehose.```
**Commits**:
```rustuse jacquard_repo::commit::Commit;
// Create and sign.let commit = Commit::new_unsigned(did, data_cid, rev, prev_cid) .sign(&signing_key)?;
// Verify.commit.verify(&public_key)?;```
**Supported signature algorithms**: Ed25519, ECDSA P-256, ECDSA secp256k1.
**Firehose validation**:
```rust// Sync v1.0 (requires prev MST state).let new_root = commit.validate_v1_0(prev_mst_root, prev_storage, pubkey).await?;
// Sync v1.1 (inductive, requires prev_data field + op prev CIDs).let new_root = commit.validate_v1_1(pubkey).await?;```
**v1.1 inductive validation**: Inverts operations on claimed result, verifies inverted result matches `prev_data`. Requires:- `prev_data` field in commit- All operations have `prev` CIDs for updates/deletes- All required MST blocks in CAR
**CAR I/O**:
```rust// Read.let parsed = parse_car_bytes(&bytes)?;let root_cid = parsed.root;let blocks = parsed.blocks; // BTreeMap<CID, Bytes>
// Write.let bytes = write_car_bytes(root_cid, blocks)?;```
**BlockStore trait**: Pluggable storage backend.
```rust#[trait_variant::make(Send)] // Conditionally Send on non-WASM.pub trait BlockStore: Clone { async fn get(&self, cid: &CID) -> Result<Option<Bytes>>; async fn put(&self, data: &[u8]) -> Result<CID>; async fn apply_commit(&self, commit: CommitData) -> Result<()>; // Atomic.}```
**Implementations**:- `MemoryBlockStore`: In-memory (testing)- `FileBlockStore`: File-based (persistent)- `LayeredBlockStore`: Read-through cache (e.g., temp over persistent for firehose)
**Repository API** (high-level):
```rustuse jacquard_repo::repo::Repository;
let repo = Repository::create(storage, did, signing_key, None).await?;
// Single operations (don't auto-commit).repo.create_record(collection, rkey, cid).await?;let old_cid = repo.update_record(collection, rkey, new_cid).await?;let deleted_cid = repo.delete_record(collection, rkey).await?;
// Batch commit.let ops = vec![ RecordWriteOp::Create { collection, rkey, record }, RecordWriteOp::Update { collection, rkey, record, prev },];let (repo_ops, commit_data) = repo.create_commit(&ops, &did, prev, &key).await?;repo.apply_commit(commit_data).await?;```
**Common mistakes**:- Forgetting immutability (not reassigning MST operations)- Not calling `validate_limits()` before creating commits (protocol violation)- Using v1.1 validation without `prev_data` field (will fail)- Missing `prev` CIDs on update/delete operations for v1.1- Not implementing `Clone` cheaply on custom `BlockStore` (use `Arc` internally)- Ignoring CID mismatch errors (indicates data corruption)
### jacquard-lexicon (code generation)
**ONLY use `just` commands** for code generation:
```bashjust lex-gen # Fetch + generatejust lex-fetch # Fetch onlyjust generate-api # Generate from existing lexicons```
**Union collision detection**: When multiple namespaces have similar type names in a union, foreign refs get prefixed with second NSID segment:
```app.bsky.embed.images -> BskyImagessh.custom.embed.images -> CustomImages```
**Builder heuristics**:- Has builder: 1+ required fields, not all bare `S`- Has `Default`: 0 required fields OR all required are bare `S`
**Empty objects**: Generate as empty structs with `#[lexicon]` attribute (adds `extra_data`), not as `Data<S>`.
**Local refs**: `#fragment` normalized to `{current_nsid}#fragment` during generation.
**Feature generation**: Tracks cross-namespace dependencies:
```tomlnet_anisota = ["app_bsky"] # Uses Bluesky embeds```
**Token types**: Unit structs with `Display` impl:
```rustpub struct ClickthroughAuthor;impl Display for ClickthroughAuthor { fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result { write!(f, "clickthroughAuthor") }}```
**Common mistakes**: Running codegen commands manually without `just` (wrong flags, paths).
---
## Anti-patterns to avoid
### Roundtripping through String
```rust// BAD.let did_str = did.as_str().to_string();let did2 = Did::new_owned(&did_str)?;
// GOOD.let did2 = did.clone();// Or for type conversion:let did2: Did<String> = did.convert();```
### Using serde_json::Value
```rust// NEVER.let value: serde_json::Value = serde_json::from_slice(bytes)?;let post: Post = serde_json::from_value(value)?;
// ALWAYS.let data: Data = serde_json::from_slice(bytes)?;let post: Post = from_data(&data)?;```
### Using FromStr when new_static() or new_owned() suffices
```rust// SLOWER (FromStr always allocates into SmolStr).let did: Did = "did:plc:abc".parse()?;
// BETTER (validates and wraps into SmolStr).let did = Did::new_owned("did:plc:abc")?;
// BEST for static strings (zero allocation).let did = Did::new_static("did:plc:abc")?;```
### Not handling Unknown variant in unions
```rust// WILL NOT COMPILE (missing Unknown variant).match embed { PostEmbed::Images(img) => { /* ... */ } PostEmbed::Video(vid) => { /* ... */ }}
// HANDLE ALL VARIANTS.match embed { PostEmbed::Images(img) => { /* ... */ } PostEmbed::Video(vid) => { /* ... */ } _ => { /* Unknown or other variants */ }}```
### Forgetting MST immutability
```rust// WRONG (loses result).mst.add(key, cid).await?;
// CORRECT (reassign).let mst = mst.add(key, cid).await?;```
### Using DeserializeOwned with CowStr or &str backing types
`DeserializeOwned` (i.e. `for<'de> Deserialize<'de>`) works perfectly with `SmolStr`-backed types. This is fine:
```rust// FINE -- SmolStr-backed types implement DeserializeOwned.let post: Post = serde_json::from_slice(&bytes)?;let post: Post<SmolStr> = serde_json::from_reader(reader)?;response.into_output()?; // Uses DeserializeOwned internally.```
However, it does NOT work with `CowStr<'_>` or `&str` backing types, because those need to borrow from the input buffer:
```rust// WRONG -- CowStr needs to borrow from input.fn bad(data: &[u8]) -> Post<CowStr<'static>> { serde_json::from_slice(data).unwrap() // Can't borrow from data!}
// CORRECT -- use method-level lifetime for zero-copy.fn good(data: &[u8]) -> Post<CowStr<'_>> { serde_json::from_slice(data).unwrap() // Borrows from data.}
// ALSO CORRECT -- use SmolStr when you don't need zero-copy.fn also_good(data: &[u8]) -> Post { serde_json::from_slice(data).unwrap() // DeserializeOwned, no borrowing needed.}```
**Rule**: `DeserializeOwned` is fine for `SmolStr`-backed types (the default). Only avoid it when you specifically want zero-copy with `CowStr<'_>` or `&str`. Use `.into_output()` for owned results and `.parse::<CowStr<'_>>()` for zero-copy.
### Calling .into_static() unnecessarily
```rust// WASTEFUL -- SmolStr types are already owned.let output = response.into_output()?;let owned = output.into_static(); // No-op! Already SmolStr-backed.
// USEFUL -- converting from CowStr to SmolStr.let borrowed: Post<CowStr<'_>> = response.parse()?;let owned: Post = borrowed.into_static(); // Converts CowStr -> SmolStr.```
### Using .as_ref() on SmolStr when .as_str() is clearer
`SmolStr` implements `AsRef<str>` but also `AsRef<[u8]>`, which can cause ambiguity:
```rust// AMBIGUOUS -- compiler can't infer which AsRef.let s = my_smol.as_ref();
// CLEAR -- use as_str() for concrete SmolStr.let s: &str = my_smol.as_str();
// FINE -- as_ref() works in generic context where S: BosStr.fn generic<S: BosStr>(val: &Did<S>) -> &str { val.as_ref()}```
---
## WASM compatibility
Core crates support `wasm32-unknown-unknown` target:- jacquard-common- jacquard-api- jacquard-identity (no DNS resolution)- jacquard-oauth
**Pattern**: `#[cfg_attr(not(target_arch = "wasm32"), trait_variant::make(Send))]`
**What's different on WASM**:- No `Send` bounds on traits- DNS resolution skipped in handle->DID chain- Tokio-specific features disabled
**Test WASM compilation**:
```bashjust check-wasm# orcargo build --target wasm32-unknown-unknown -p jacquard-common --no-default-features```
---
## Quick reference
### String type constructors
| Method | Allocates? | Use when ||--------|-----------|----------|| `new(S)` | Depends on S | Wrapping an already-constructed S || `new_static(&'static str)` | No | Static string literal || `new_owned(impl AsRef<str>)` | SmolStr: inline/Arc | Validating from &str || `borrow(&self) -> Type<&str>` | No | Cheap temporary access || `convert::<B>(self) -> Type<B>` | Depends on B | Cross-type conversion || `FromStr::parse()` | SmolStr: inline/Arc | Don't care about explicitness |
### Response parsing
| Method | Backing type | Allocates? | Use when ||--------|-------------|-----------|----------|| `.into_output()` | `SmolStr` | Yes (DeserializeOwned) | Most code -- owned, no lifetime concerns || `.parse::<CowStr<'_>>()` | `CowStr<'_>` | No (zero-copy) | Performance-critical, response stays alive || `.parse::<&str>()` | `&str` | No (zero-copy) | Cheapest, response stays alive || `.parse_data()` | `CowStr<'_>` | No | Untyped Data access || `.parse_raw()` | `'_` | No | Untyped RawData access |
### XRPC traits
| Trait | Side | Key types ||-------|------|-----------|| `XrpcRequest` | Client + Server | `type Response: XrpcResp`, requires `Serialize` || `XrpcResp` | Client + Server | `type Output<S: BosStr>`, `type Err: DeserializeOwned` || `XrpcEndpoint` | Server | `type Request<S: BosStr>`, `type Response: XrpcResp` || `XrpcClient` | Client | `base_uri()`, `send()` || `XrpcExt` | Client | Stateless XRPC builder on any HttpClient |
### Session types
| Type | Auth method | Auto-refresh | Storage ||------|------------|--------------|---------|| `CredentialSession` | Bearer (app password) | Via refreshSession | SessionStore || `OAuthSession` | DPoP (OAuth) | Via token endpoint | ClientAuthStore |
### BlockStore implementations
| Type | Persistent? | Use case ||------|------------|----------|| `MemoryBlockStore` | No | Testing || `FileBlockStore` | Yes | Production || `LayeredBlockStore` | Depends | Read-through cache |
---
## Common operations
### Making an XRPC call
```rustuse jacquard::api::app_bsky::feed::get_author_feed::GetAuthorFeed;
let request = GetAuthorFeed::new() .actor("alice.bsky.social".into()) .limit(50) .build();
let response = agent.send(request).await?;let output = response.into_output()?;
for post in output.feed { println!("{}: {}", post.post.author.handle, post.post.uri);}```
### Creating a record
```rustuse jacquard::api::app_bsky::feed::post::Post;use jacquard::common::types::string::Datetime;
let post = Post::builder() .text("Hello ATProto from Jacquard!") .created_at(Datetime::now()) .build();
agent.create_record(post, None).await?;```
### Resolving identity
```rustuse jacquard::identity::PublicResolver;
let resolver = PublicResolver::default();
// Handle -> DID.let did = resolver.resolve_handle(&handle).await?;
// DID -> PDS endpoint.let pds = resolver.pds_for_did(&did).await?;
// Combined.let (did, pds) = resolver.pds_for_handle(&handle).await?;```
### OAuth login
```rustuse jacquard::oauth::client::OAuthClient;use jacquard::client::FileAuthStore;
let oauth = OAuthClient::with_default_config( FileAuthStore::new("./auth.json"));
let session = oauth.login_with_local_server( "alice.bsky.social", Default::default(), Default::default(),).await?;
let agent = Agent::from(session);```
### Working with different backing types
```rust// Default SmolStr-backed (most common).let did = Did::new_owned("did:plc:abc123")?;
// Cheap borrow for function calls.let borrowed: Did<&str> = did.borrow();some_function(&borrowed);
// Zero-copy parsing.let response = agent.send(request).await?;let output: GetPostOutput<CowStr<'_>> = response.parse()?;// Process output while response is alive...
// Convert to owned when needed.let owned: GetPostOutput = output.into_static();```
### Server-side XRPC handler
```rustuse jacquard_axum::{ExtractXrpc, IntoRouter};use jacquard::common::DefaultStr;use axum::{Router, Json};
async fn handler( ExtractXrpc(req): ExtractXrpc<MyRequest, DefaultStr>) -> Json<MyOutput> { // Process request. Json(output)}
let app = Router::new() .merge(MyRequest::into_router(handler));```
### MST operations
```rustuse jacquard_repo::mst::Mst;use jacquard_repo::storage::MemoryBlockStore;
let storage = MemoryBlockStore::new();let mst = Mst::new(storage.clone());
let mst = mst.add("app.bsky.feed.post/abc123", record_cid).await?;let mst = mst.add("app.bsky.feed.post/xyz789", record_cid2).await?;
let root_cid = mst.persist().await?;```
---
## Documentation links
- [docs.rs/jacquard](https://docs.rs/jacquard/latest/jacquard/)- [docs.rs/jacquard-common](https://docs.rs/jacquard-common/latest/jacquard_common/)- [docs.rs/jacquard-api](https://docs.rs/jacquard-api/latest/jacquard_api/)- [docs.rs/jacquard-oauth](https://docs.rs/jacquard-oauth/latest/jacquard_oauth/)- [docs.rs/jacquard-identity](https://docs.rs/jacquard-identity/latest/jacquard_identity/)- [docs.rs/jacquard-repo](https://docs.rs/jacquard-repo/latest/jacquard_repo/)- [docs.rs/jacquard-axum](https://docs.rs/jacquard-axum/latest/jacquard_axum/)- [Repository](https://tangled.org/@nonbinary.computer/jacquard)
---
## Philosophy summary
Jacquard is designed for **correctness**, **performance**, and **ergonomics** in that order. It favors:
1. **Validation at construction time** - Invalid inputs fail fast, not deep in your code2. **Flexible string backing** - `SmolStr` for owned types with `DeserializeOwned` support, `CowStr`/`&str` for zero-copy when needed3. **Explicit type control** - You choose the backing type via `S: BosStr`, with sensible defaults4. **Type safety without boilerplate** - Generated bindings just work, with strong typing and builders5. **Batteries included, but replaceable** - High-level `Agent` for convenience, low-level primitives for control
**When in doubt**: Use the default `SmolStr`-backed types, call `.into_output()` for owned responses, use `.borrow()` for cheap access, and trust the type system. Jacquard is designed to guide you toward correct, performant code.