Replaces the W-026 501 stub. Re-executes a journaled prompt in a sealed
fresh runtime (ChatRuntime(no_load_state=True): no checkpoint load, no
checkpoint write, no proposal lineage) and compares the envelope
leaf-by-leaf against the recorded TurnJournalEntry.
Design correction vs the scoping doc (amended in-doc): journaled turns
each ran in a fresh ChatRuntime(), never one continuous session, so
genesis-PREFIX replay would manufacture spurious divergence; shipped
basis is sealed_fresh_runtime_single_turn (O(1)). origin_state:
"unrecorded" — the journal does not record whether the original turn's
runtime loaded a checkpoint, so divergence is reported as nondeterminism
OR origin-state influence, never disambiguated.
- workbench/replay.py: pure comparison + injected executor; every
TurnJournalEntry field classified critical/informational exactly once
(exhaustiveness enforced by test)
- api.py: route wiring under _CHAT_TURN_LOCK; runtime failure -> 500
runtime_unavailable, no comparison may be fabricated
- schemas: additive TurnReplayComparison/TurnReplayDivergence (W-026
artifact-keyed pair retires with the frontend Replay Moment PR)
- tests: 10 obligations incl. tamper-prompt, tamper-leaf precision,
no-execution-no-comparison, no-trace (journal + engine_state bytes),
wall-clock tolerance, sealed-construction proof
- snapshot regenerated; NOT_YET_MIRRORED debt entries for the two new
classes (mirrors land with the frontend PR)
- api-contract-v1.md § Replay rewritten for the turn-keyed shape
