feat(sdk): session-filtered change feed and a paged read of every session identity

CHANGELOG.md

@@ -184,6 +184,28 @@ Notable changes to the native `ai-hist` CLI are documented here.
 
 ### Rust API
 
+- `ChangeQuery::session(source, session_id)` restricts a change-feed drain
+  to one session: the same `Change` values the unfiltered drain reports for
+  that session, tombstones included, read through each table's
+  `(source, session_id)` index rather than the whole revision range. It is a
+  one-shot read (a session's backfill), so naming a consumer alongside it is
+  `Error::InvalidArgument`. A prompt with no session belongs to no session's
+  drain, and a trajectory is the session its id names under the `trajectory`
+  source.
+- `SessionStore::session_identities(IdentityQuery { after, limit })` pages
+  every `(source_name, session_id)` the store holds evidence under, catalogued
+  or not: the union of the catalog, prompts, events, tool calls, file edits,
+  markers, relationships (by parent), presences, commit links, connector
+  observations and trajectories. It is a merge of covering index seeks, so no
+  payload is read; each page reads one snapshot, and an empty session id is
+  no session. `SessionIdentity` names a stored session, including one
+  under a source this build does not know, and is the type
+  `ChangeQuery::session` holds. `storage::session_identities_after` is the
+  same read, and now covers every one of those tables rather than the catalog,
+  prompts and events alone, and reads each page on one snapshot even on an
+  autocommit connection. `sessions` gains `idx_sessions_identity` on
+  `(source, session_id)`, added by the first writable open; until then a
+  read-only store answers `session_identities` with `StaleSchema`.
 - The change feed reports every evidence table and each row exactly as
   stored. `ChangeKind` gains `History`, `Presence`, `CommitLink`,
   `Trajectory`, `SourceObservation` and `ObservationEvidence` (`ALL` lists

crates/ai-hist/README.md

@@ -29,7 +29,7 @@ fn main() -> Result<(), ai_hist::Error> {
 }
 ```
 
-Default features expose `SessionStore` — `open`, `discover`, `sync`, `hydrate`, `watch`, `sessions`, `session`, `changes_since`, `head_revision` — plus `Source::capabilities()`, the typed evidence structs and one `Error` enum; see `docs/sourcing-sdk.md` in the repository. Optional features: `export` (consistent snapshots and change capture), `opencode-backup`, `git-hooks`, `fs-events`. The legacy `delivery` feature aliases `export`; upload jobs and workers are owned by the probe package, `plugins/relayhistory/rust`. Workspace crates enable `unstable-internal` for connection-level maintenance APIs.
+Default features expose `SessionStore` — `open`, `discover`, `sync`, `hydrate`, `watch`, `sessions`, `session`, `session_identities`, `changes_since`, `head_revision` — plus `Source::capabilities()`, the typed evidence structs and one `Error` enum; see `docs/sourcing-sdk.md` in the repository. Optional features: `export` (consistent snapshots and change capture), `opencode-backup`, `git-hooks`, `fs-events`. The legacy `delivery` feature aliases `export`; upload jobs and workers are owned by the probe package, `plugins/relayhistory/rust`. Workspace crates enable `unstable-internal` for connection-level maintenance APIs.
 
 The embedder guide — store options, the sync lifecycle and its locking, the evidence model, accounting semantics, versioning and feature flags — is [`docs/sourcing-sdk.md`](https://github.com/AgentWorkforce/relayhistory/blob/main/docs/sourcing-sdk.md), and [`examples/rust-consumer`](https://github.com/AgentWorkforce/relayhistory/tree/main/examples/rust-consumer) is a standalone project that consumes this crate from crates.io. Cargo semver is the contract; the crate's default-feature public API is snapshotted in the repository at `crates/ai-hist/public-api.txt` and diffed in CI.
 

crates/ai-hist/public-api.txt

@@ -315,10 +315,12 @@ pub ai_hist::Change::source_name: alloc::string::String
 pub ai_hist::ChangeQuery::batch: usize
 pub ai_hist::ChangeQuery::consumer: core::option::Option<alloc::string::String>
 pub ai_hist::ChangeQuery::kinds: core::option::Option<alloc::vec::Vec<ai_hist::ChangeKind>>
+pub ai_hist::ChangeQuery::session: core::option::Option<ai_hist::SessionIdentity>
 impl ai_hist::ChangeQuery
 pub fn ai_hist::ChangeQuery::batch(self, usize) -> Self
 pub fn ai_hist::ChangeQuery::consumer(self, impl core::convert::Into<alloc::string::String>) -> Self
 pub fn ai_hist::ChangeQuery::kinds(self, impl core::iter::traits::collect::IntoIterator<Item = ai_hist::ChangeKind>) -> Self
+pub fn ai_hist::ChangeQuery::session(self, impl core::convert::Into<alloc::string::String>, impl core::convert::Into<alloc::string::String>) -> Self
 pub struct ai_hist::Changes
 impl ai_hist::Changes
 pub fn ai_hist::Changes::commit(&self) -> anyhow::Result<ai_hist::Watermark, ai_hist::Error>
@@ -384,6 +386,12 @@ pub ai_hist::HydrateReport::diagnostics: alloc::vec::Vec<ai_hist::Diagnostic>
 pub ai_hist::HydrateReport::related: alloc::vec::Vec<ai_hist::SessionRef>
 pub ai_hist::HydrateReport::session: ai_hist::SessionRef
 pub ai_hist::HydrateReport::status: ai_hist::HydrateStatus
+#[non_exhaustive] pub struct ai_hist::IdentityQuery
+pub ai_hist::IdentityQuery::after: core::option::Option<ai_hist::SessionIdentity>
+pub ai_hist::IdentityQuery::limit: usize
+impl ai_hist::IdentityQuery
+pub fn ai_hist::IdentityQuery::after(self, ai_hist::SessionIdentity) -> Self
+pub fn ai_hist::IdentityQuery::limit(self, usize) -> Self
 #[non_exhaustive] pub struct ai_hist::Marker
 pub ai_hist::Marker::kind: alloc::string::String
 pub ai_hist::Marker::marker_uid: alloc::string::String
@@ -558,6 +566,12 @@ pub ai_hist::SessionFileEdit::tool_name: core::option::Option<alloc::string::Str
 pub ai_hist::SessionFileEdit::tool_use_id: alloc::string::String
 pub ai_hist::SessionFileEdit::ts_ms: core::option::Option<i64>
 pub ai_hist::SessionFileEdit::user_modified: core::option::Option<i64>
+#[non_exhaustive] pub struct ai_hist::SessionIdentity
+pub ai_hist::SessionIdentity::session_id: alloc::string::String
+pub ai_hist::SessionIdentity::source_name: alloc::string::String
+impl ai_hist::SessionIdentity
+pub fn ai_hist::SessionIdentity::new(impl core::convert::Into<alloc::string::String>, impl core::convert::Into<alloc::string::String>) -> Self
+pub fn ai_hist::SessionIdentity::source(&self) -> core::option::Option<ai_hist::Source>
 pub struct ai_hist::SessionMarker
 pub ai_hist::SessionMarker::id: i64
 pub ai_hist::SessionMarker::kind: alloc::string::String
@@ -635,6 +649,8 @@ pub fn ai_hist::SessionStore::session(&self, &ai_hist::SessionRef, ai_hist::Sess
 pub fn ai_hist::SessionStore::sessions(&self, ai_hist::CatalogQuery) -> ai_hist::CatalogIter
 pub fn ai_hist::SessionStore::sync(&self, ai_hist::SyncOptions) -> core::result::Result<ai_hist::SyncReport, ai_hist::Error>
 pub fn ai_hist::SessionStore::watch(&self, ai_hist::WatchOptions) -> core::result::Result<ai_hist::WatchHandle, ai_hist::Error>
+impl ai_hist::SessionStore
+pub fn ai_hist::SessionStore::session_identities(&self, ai_hist::IdentityQuery) -> core::result::Result<alloc::vec::Vec<ai_hist::SessionIdentity>, ai_hist::Error>
 pub struct ai_hist::SessionToolCall
 pub ai_hist::SessionToolCall::args_json: core::option::Option<alloc::string::String>
 pub ai_hist::SessionToolCall::id: i64