[aw-failures] Failure Investigation Report — 2026-04-21 (6h window)

[github-actions]

Executive Summary

Two Design Decision Gate (claude engine) failures were detected in the 2026-04-21 investigation window. Both share an identical root cause: the workflow's 5-turn max-turns budget is insufficient for the ADR generation path. 19 of 23 runs in the window succeeded; the failures are isolated to this one workflow/root-cause combination.

Closed stale issue #27405 (expired, different root cause — MCP connection drop).

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Failure Clusters

Cluster	Workflow	Engine	Count	Root Cause	Priority
DDG max-turns	Design Decision Gate	claude	2	max_turns=5 insufficient for ADR write+push path	P1

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Evidence

Failed Runs

Run ID	Branch / PR	Turns Used	Terminal Reason	ADR Written?
§24698134887	copilot/configure-agentic-engine-driver (PR #27453)	5/5	max_turns	Locally written, never pushed
§24697778261	copilot/add-support-agentic-engine-opencode (PR #27466)	5/5	max_turns	Not written (cut off mid-turn)

Comparator (success): §24697555895 — PR #27458, no ADR required → noop in 4 turns ✅

Turn-by-turn breakdown for run §24698134887

Turn	Action	Result
1	Read adr-prefetch-summary.json + design-gate-config.yml	186 additions → ADR required
2	Read pr.json + pr.diff	Full diff across 9 files
3	Check existing ADRs	None found for PR #27453
4	mkdir -p docs/adr	Success
5 (last)	Write docs/adr/27453-*.md	File written locally (6,195 bytes) — no turn left for push
—	Hit max_turns	push_to_pull_request_branch + safeoutputs never called

Turn-by-turn breakdown for run §24697778261

Turn	Action	Result
1	Read adr-prefetch-summary.json + design-gate-config.yml	520 additions → ADR required
2	Read pr.json + pr.diff	24 files, 520+ additions
3	Read file list (extra data-gathering step)	Turn consumed before ADR write
4	mkdir -p docs/adr	Success
5 (last)	Write ADR initiated	Hit max_turns before write completed

Root Cause

The "ADR needed" execution path requires a minimum of 6 turns:

1. Read prefetch summary + config
2. Read PR metadata + diff
3. Check existing ADRs
4. mkdir docs/adr
5. Write ADR file
6. Push to PR branch + call safeoutputs

The workflow is configured with max_turns=5, making this path structurally impossible to complete.

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Existing Issue Correlation

Issue	Status	Action
#27405 — Design Decision Gate failed (MCP connection drop)	Closed ✅	Expired (Apr 21 05:36 UTC) + different root cause
#27411 — Failure Investigator Issue Group	Open	Parent for new sub-issues

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Fix Roadmap

Priority	Fix	Effort
P1	Increase max-turns from 5 → 7 in DDG workflow	Low
P1 (alt)	Move mkdir docs/adr to pre-agent shell step	Low
P2	Combine Write + push_to_pull_request_branch into a single tool call	Medium

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Sub-Issues Created

• [aw-failures] Design Decision Gate: increase max-turns for ADR generation path #27470 — Design Decision Gate: increase max-turns for ADR generation path

References:

• §24698134887
• §24697778261
• §24697555895