Files
turnstone/tests
Patrick Buckley 2e18d159a3 feat(session): fold the main streaming loop onto model_turn (#832)
The send path's plant call is now one model_turn invocation per attempt,
reached through a lane-swap fallback walk that mirrors the old creation
ladder 1:1: an inner per-lane retry (_model_turn_with_retry) inside the
two-pass healthy/degraded walk (_model_turn_with_fallback), with health
success recorded at the request-accepted instant via the per-attempt
_CancelRef's new on_first_append hook and failure once per lane ladder.
The hook is also the creation-vs-midstream classifier: an armed attempt's
death re-raises to the re-issue ladder on every lane — a fallback stream
that died after tokens reached the UI is never swallowed into
try-the-next-alias — and carries the per-turn usage-slot resets at the
old timing so a reconnecting tab's status bar never blanks mid-walk.

Chunk-to-UI translation lives in _StreamTurnConsumer (model_turn's
on_chunk body): display-side only, the canonical turn always assembled by
drain_stream at the one seam; the inline-tag scan reads the SAME lane
capability the drain gate reads (server_parses_reasoning), replacing the
creation-time handoff register — which is deleted — so display and commit
cannot disagree about a backend's posture, fallback walk included.
Cancellation converges: every model-call site now builds fresh
generation-scoped refs, closing the force-cancel hole where the old gen-0
shared ref read aborted=False for an orphaned generation and would have
let a retry re-issue on its behalf; the pre-dispatch abort read inside
model_turn also means a Stop set before the turn no longer mints a
credential on a dynamically authenticated alias.

send() consumes the result natively: the committed Turn carries minted
ids, the finalized native lane, and an accurate producer — fixing the
latent mislabel where fallback-served turns were persisted under the
primary provider's name, and the fork asymmetry where in-memory turns
decoded with producer="". Ruled behavior changes (design D12): the
trailing citations footer now folds into committed content (it previously
lived only in an ephemeral info bubble and vanished on reload); a stream
that exhausts without a finish reason is a retryable mid-stream death
instead of a silent partial commit; length-truncated turns keep dropping
partial tool calls, now as an explicit post-drain policy. The replay
parity harness pins all thirteen scenarios against pre-fold baselines,
transformed only where a ruling applies — and caught two real bugs during
the fold (the splitter's end-of-stream carry never flushing to the UI,
and the footer splicing into the answer's held tail).

ChatSession imports no provider module: create_streaming has exactly one
caller module, and the protocol types, merge_usage, and create_provider
reach the session through model_turn's re-export seam.
2026-08-06 01:04:32 -07:00
..