Merge branch 'worktree-agent-a6e37a2335f436d08' into rustify

docs/RUST.md

@@ -177,12 +177,32 @@ closes it.
       touch pan from the same mechanism `List` uses, not a copy.
 - [ ] **Streaming re-layout** (IRIS_TODO.md's last section) — after the
       above, since they make the stream phase unrepresentative today.
-- [ ] **client-core prerequisites for P1, in parallel** (pure Rust,
-      disjoint from `iris/`): `TranscriptSource`'s cache-vs-server
-      stitching and `joinPages`/`healSplitMessage`/`adoptRun` page-boundary
-      healing, per `CLIENT_CORE.md`. Ported with the Kotlin tests as the
-      spec. Cheap to have ready if P0 passes, and no rendering risk if
-      it does not.
+- [x] **client-core prerequisites for P1, in parallel** (pure Rust,
+      disjoint from `iris/`), closed 2026-09-06: `TranscriptSource`'s
+      cache-vs-server stitching (new `client-core/src/transcript_source.rs`)
+      and `joinPages`/`healSplitMessage`/`adoptRun` page-boundary healing
+      (new functions in `transcript_fold.rs`), per `CLIENT_CORE.md`. Ported
+      against the Kotlin source and AGENTS.md's paging incidents as the
+      spec (`TranscriptSource.kt`/`TranscriptItems.kt` had no JVM unit
+      tests of their own to port test-for-test). `client-core` goes from
+      85 to 109 tests; `cargo test`/`clippy --all-targets`/`fmt` all clean.
+      Both AGENTS.md regressions have a dedicated test: `loadOlderPage`'s
+      `before == 0` guard moved into `TranscriptSource::page` itself
+      (`paging_before_the_first_event_makes_no_request_at_all` asserts
+      zero transport calls, not just an empty result), and
+      `a_clean_boundary_between_two_finished_runs_is_still_healed_into_one_run`
+      pins `adopt_run` running on *every* join rather than only the
+      split-call path. One incidental fix needed to port `TranscriptSource`
+      faithfully: `api.rs` gained `fetch_transcript_lines` (additive, the
+      existing `fetch_transcript_page` untouched since `iris/` depends on
+      its signature), which pairs each event with the exact server bytes
+      it came from via `serde_json::value::RawValue` rather than
+      re-serializing a parsed `Value` -- needed so the cache and a live SSE
+      frame agree byte-for-byte, the same class of bug as the
+      `float_roundtrip` fix. Deliberately not ported: `EventStream.kt`'s
+      reconnect/backoff and cross-thread stream cancellation, which are
+      runtime policy for whichever framework embeds this crate, not pure
+      logic -- see `CLIENT_CORE.md`'s new section for the full account.
 - **Then**: redeliver `~/host/bench/iris-bench-arm64.apk` for Iris with
   its README saying what changed, and record any choice she should see in
   `DECISIONS.md`.