Review of 73251d6's port of TranscriptSource/joinPages.
`TranscriptSource::page` answered `before == 0` with an empty `Vec`, which
is the same value it answers "this conversation has no more history" with.
That is the state the Kotlin keeps apart: `loadOlderPage` returns false at
`oldestSeq == 0` *without* touching `moreHistory`, and returns false on an
empty page *by latching it*. Collapsing the two moved AGENTS.md's paging
bug one layer down rather than fixing it. `page` returns `OlderPage` now --
`Events(vec![])` is the start of the conversation, `NothingLoaded` is not
an answer about the conversation at all.
`join_pages`' `debug_assert!` on seq ordering across the boundary is not a
true invariant: a peer note carries the seq its turn began at, which can be
older than the page it arrived in, so an ordinary transcript would have
panicked a debug build there. Replaced with the one the function exists to
enforce -- no tool id surviving in both halves.
`fetch_transcript_lines` stores `RawValue`'s exact server bytes, so the
"neither source can produce a newline" comment in `SessionCache::append`
now rests on the server's serializer staying compact rather than on a
local normalization. Checked with a `debug_assert!` in `append` and
`store_page` rather than trusted.
Tests for the failure half, which the port had none of: a 500 mid-page, a
cached line this build cannot read, and the `after` bound in the case that
actually carries one (the existing test asserted only the case with no
bound). `cargo fmt`, `cargo clippy --all-targets`, `cargo test` (112) clean
in client-core; `cargo check -p desktop-app` clean.
Closes docs/RUST.md's "client-core prerequisites for P1" box: the
cache-vs-server stitching TranscriptSource.kt does, and the
joinPages/healSplitMessage/adoptRun page-boundary healing
TranscriptItems.kt does, both ported into client-core with no UI
framework dependency.
Neither Kotlin file had a JVM unit test of its own, so the port used the
Kotlin source and AGENTS.md's "things that have bitten" paging incidents
as the spec instead of a test-for-test transcription. Both regressions
get a dedicated test: TranscriptSource::page refuses before == 0 before
touching the cache or the network (loadOlderPage's incident), and
adopt_run now runs on every page join rather than only the one where a
split call was found (the "one run drawn as two" incident).
fetch_transcript_lines (api.rs, additive) pairs each transcript line with
the exact server bytes via serde_json::value::RawValue rather than
re-serializing a parsed Value, so a cached line and a live SSE frame for
the same event agree byte-for-byte -- the fetch_transcript_page other
callers under iris/ depend on is untouched.
client-core: 85 -> 109 tests. cargo test/clippy --all-targets/fmt clean.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>