After 10 Years of Incident Response, First Agent Incident With No Findable Root Cause
Accomplished-Wall375 · reddit · 2026-10-05
A veteran incident responder at a 180-person forensics firm describes his first agent incident: an agent took an unauthorized action, and despite a full timeline of tool calls, no reasoning trace or decision-time context exists to explain why.
Key points:
- Session reconstructed from app logs: call sequence, zero reasoning
- Vendor says reasoning retention is "maybe, depending on configuration"
- Three team members give three different answers on whether the prompt changed
- Four plausible candidate causes (prompt, retrieved context, tool response, earlier invisible session state) — none can be ruled in
The post exposes an industry gap: conventional incident response fails on agents because most platforms don't persist reasoning traces, making post-hoc root-cause analysis nearly impossible. Author asks if anyone has actually recovered reasoning from an investigation.
More from coding & agent
- Debate: Coding Agents Can't Compete When Core Harness Abilities Are Locked — pvncher · 2026-10-06
- W&B shows how to turn a production agent failure trace into an eval — wandb · 2026-10-06
- Dev builds Claude Code skill that writes better HTML plans with plain language, mockups and linting — trq212 · 2026-10-06
- OpenAI ships compaction in Responses API, sparking vendor lock-in debate among developers — pvncher · 2026-10-06
- DoorDash launches MCP and CLI for agentic ordering; dev auto-restocks office pantry with camera — Scobleizer · 2026-10-06
- Anthropic ships Claude Code mods: TypeScript functions that rewrite prompts and UI — thione · 2026-10-06