2026-08-20-turn-error-survives-same-turn-retry-history.md 3.6 KB
Agent Note: Terminal turn errors survive same-turn retry history
Status: implemented
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Problem
The Web turn-error Definition suppressed its node permanently once the owning turn carried any llm/retry event. That rule encoded the retry model bounded LLM request recovery originally shipped, where a retry closed the failed turn and opened the next numbered one: a turn with retry history could only be an intermediate failure whose facts already lived on the retry row, and the exhausted terminal failure landed in a later turn with no retry events.
The agent loop has since retried inside the failing turn and step — llm-retry's runtime invariant requires llm/retry inside an open turn and step, and its loop tests assert a recovered turn holds one step/start. Under that producer, "the turn owns retry history" and "this turn/end error is the exhausted terminal failure" always coincide, so the suppression hid exactly the failure it existed to defer to: exhausting every transient retry left the conversation with a neutral collapsed "Retried model request (N/N)" row, no error row, and a re-enabled composer. The live e2e scenarios missed the gap because they covered a non-retryable AUTH failure (no retry events, so the row rendered) and a transient failure that recovered (a completed turn derives no failure), never exhaustion.
Decision
Delete the suppression. The turn-error Definition matches only turn/start and error-reason turn/end, and renders whenever its turn recorded a terminal error; the settled retry chain renders beside it through the separate model-retry node. No hidden state, no retraction branch: with same-turn retries there is no event order in which a rendered terminal error is later superseded, because turn/end closes the turn.
Partial history windows behave identically by construction — a tail window containing only the error-reason turn/end derives the same node the full history does, where the old rule hid one and showed the other depending on which retry events the window happened to include.
Testing
The Definition suite drives the real assembler through a same-turn retry chain ending in an error-reason turn/end and asserts the turn-error node materializes with its message and code — in full history, in a tail-only window, and after prepending the earlier chain. A keyless Web composition scenario exhausts a scenario-owned two-retry policy against three injected SERVER throws and pins the terminal error row beside the settled retry row in the golden; the scaffold gained a replayRetryPolicy option so exhaustion runs in milliseconds instead of the shared default's five backed-off attempts.
Alternatives considered
Reset hidden when the terminal failure arrives. Rejected: it keeps a state machine whose only remaining transition is the one that caused the bug. Under same-turn retries no event sequence needs the suppression at all.
Distinguish intermediate from terminal turn/end errors. Rejected: the distinction does not exist in the log. A turn ends once; an error reason is always terminal for its turn.
Consequences
Exhausted recovery now leaves durable, replayable feedback: the red terminal row with the display-safe message and code, plus the collapsed retry chain as recovery context. Session logs recorded under the retired new-turn retry model render one turn-error row per failed turn on replay; the v0-to-v1 edge preserves those terminal facts, and no shipped log producer has emitted that shape since same-turn retries landed.