fix(server): dismiss native questions after their turn ends

[rynfar]

When a native provider turn ended with an unanswered question, the thread could retain a pending-input form that could no longer receive an answer. Resolve unanswered native questions for the exact terminal turn, including completed, failed, interrupted and aborted outcomes.

Adopts approved B5, upstream #9851, d7fe47fd0957a34fc2e8bb05f12db19bac3403b6. Uses Pylon’s existing guarded dispatch, session-incarnation checks and drainable worker. Prime interaction records, answered questions, other turns and explicitly stored message-mode activities are preserved. Does not import upstream’s separate async-question API. Applies to all native providers and every client/connection mode.

Validation: 91 focused ingestion tests pass, including duplicate terminal events, all terminal outcomes, answered/newer/child requests and a retired session attempting to clear a current session’s question. Server typecheck, targeted lint and diff checks pass. Tests use isolated in-memory persistence and worker drains.

Model: GPT-6 Astra. Harness: Codex.

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[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	13.6 KiB	13.6 KiB	−4 B (−0.0%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.1 KiB	7.1 KiB	−3 B (−0.0%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.5 KiB	6.5 KiB	−1 B (−0.0%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	56.5 KiB	56.5 KiB	0 B (0.0%)	66.4 KiB	✅
Codex	Live turn messages	8	8	0 (0.0%)	21	✅
Claude	Total thread wire	13.6 KiB	13.6 KiB	−17 B (−0.1%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.1 KiB	7.1 KiB	−5 B (−0.1%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.6 KiB	6.5 KiB	−12 B (−0.2%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	57.3 KiB	57.3 KiB	0 B (0.0%)	66.4 KiB	✅
Claude	Live turn messages	8	8	0 (0.0%)	21	✅

Baseline: e58f82c · PR result: cae470f · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 111.2 KiB
• Claude decoded thread snapshot: 111.9 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.