5e6a16d473
TurnEvent had no trace_hash field, so teaching/discovery._trace_hash always returned "" via getattr default. Every persisted DiscoveryCandidate had source_turn_trace="" — provenance gap observed in a real 103-turn session. - Add trace_hash: str = "" to TurnEvent - runtime.finalize_turn_trace_hash back-stamps last TurnEvent and unstamped tail of _pending_candidates, then re-persists - CognitiveTurnPipeline.process calls finalize_turn_trace_hash after compute_trace_hash, before constructing CognitiveTurnResult Invariants: empty hash is a no-op; back-walk halts at first already- stamped candidate (no overwrite of prior turns); trace_hash bytes are unchanged for any given turn. Validated: tests/test_adr_0153_trace_hash_backstamp.py (6 tests), core test --suite cognition/smoke/runtime/teaching all green. Out of scope: OOV candidate trace_hash (same root cause, line-streamed sink requires different fix); telemetry-sink trace_hash exposure.
83 lines
3.3 KiB
Markdown
83 lines
3.3 KiB
Markdown
# ADR-0153 — TurnEvent trace_hash back-stamp (W-020a)
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Status: accepted
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Date: 2026-05-25
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## Context
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`teaching/discovery.py` documents that `DiscoveryCandidate.source_turn_trace`
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"is the upstream `TurnEvent.trace_hash`" (module docstring, line 41).
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The extractor reads it via:
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```python
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def _trace_hash(turn_event: Any) -> str:
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value = getattr(turn_event, "trace_hash", "") or ""
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return str(value)
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```
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But `TurnEvent` (`core/physics/identity.py`) has no `trace_hash` field.
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Every `DiscoveryCandidate` written to disk had `source_turn_trace=""`.
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Same defect at `chat/runtime.py:874` for `OOVCandidate`.
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The real `trace_hash` is computed by `core/cognition/trace.py:compute_trace_hash`
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inside `CognitiveTurnPipeline.process` **after** `runtime.chat()` returns —
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which is after `_emit_discovery_candidates` has already buffered and
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`_checkpointed_response` has already persisted the candidates.
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Symptom observed: a 103-turn session wrote a `discovery_candidates.jsonl`
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whose one candidate had `"source_turn_trace": ""` — provenance lost.
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## Decision
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1. Add `trace_hash: str = ""` to `TurnEvent`.
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2. Add `ChatRuntime.finalize_turn_trace_hash(trace_hash)`. Back-stamps:
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- `turn_log[-1]` (via `dataclasses.replace`)
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- the unstamped tail of `_pending_candidates`
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- re-persists `discovery_candidates.jsonl`
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3. `CognitiveTurnPipeline.process` calls `finalize_turn_trace_hash` after
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`compute_trace_hash`, before constructing `CognitiveTurnResult`.
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The back-walk halts at the first already-stamped candidate, so prior
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turns' candidates are never overwritten.
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## Invariants
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- Empty `trace_hash` is a no-op (refusal/stub call sites do not lose
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byte-identity).
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- Re-stamping is idempotent for the most recent turn and forbidden for
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earlier turns.
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- No change to `compute_trace_hash` inputs — trace_hash bytes for any
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given turn remain identical to pre-ADR-0153.
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- No change to `TurnEvent` telemetry sink emission order (sinks receive
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the pre-stamp event; the persisted record gets the stamped one). A
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follow-up may add a "turn finalized" sink event with the trace_hash.
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## Out of scope
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- OOV candidates (`OOVCandidate.source_turn_trace`) — same root cause,
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but the sink is line-streamed at emit time, not buffered. Fix
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requires either buffering OOV or computing trace_hash earlier.
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Tracked separately; no production OOV sink was configured during
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the observed regression.
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- Telemetry sink trace_hash exposure — see invariants above.
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## Validation
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`tests/test_adr_0153_trace_hash_backstamp.py`:
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- `TurnEvent.trace_hash` field exists with default `""`
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- main-path `pipe.run` stamps `turn_log[-1].trace_hash == result.trace_hash`
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- main-path `pipe.run` stamps `_pending_candidates[*].source_turn_trace`
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- on-disk `discovery_candidates.jsonl` reflects the stamped values
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- empty trace_hash is a no-op
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- idempotent: prior stamps are not overwritten
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CLI lanes: `core test --suite cognition` (120 + 1 skipped),
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`core test --suite smoke` (67), `core test --suite runtime` (17),
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`core test --suite teaching` (20) all green.
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## Provenance gap closure
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After this ADR, every `DiscoveryCandidate` persisted via the
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load-time auto-proposal pipeline (ADR-0151) carries the canonical
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trace_hash of the turn that produced it, restoring the audit-trail
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invariant the discovery module's docstring already promised.
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