[aw-failures] [fix] Multi-Device Docs Tester: session resume failure — 4-day consecutive streak #30796

Problem Statement

The Multi-Device Docs Tester workflow has failed on every scheduled run since 2026-05-04 (4 consecutive days). No actual testing work ever executes — the harness defers the session during initialization, then fails to resume it on all 3 retry attempts with exit code 1.

Parent report: [aw] Failure Report 2026-05-07: Session Resume Regression + Schema Checker Max-Turns Escalation

Affected Runs

Last successful run: §25271781842 (2026-05-03)

Root Cause

Harness session-resume error in Claude Code v2.1.126:

Error: No deferred tool marker found in the resumed session. Either the session was not
deferred, the marker is stale (tool already ran), or it exceeds the tail-scan window.
Provide a prompt to continue the conversation.

[claude-harness] all 3 retries exhausted — giving up (exitCode=1)
[claude-harness] done: exitCode=1 totalDuration=3m 10s

Additional signal: [DEBUG] Prior session exited uncleanly: 6655b237-5666-42c3-b6bf-2e1473e87727 (v2.1.126)

The workflow defers its session during pre-agent initialization, but when the harness attempts to resume, the deferred-tool marker is missing or expired. All 3 retries hit the same error instantly (duration=0s stderr=221B).

Audit-diff confirms the failed run never reaches the actual test phase — no playwright MCP tool calls, no Android/Google domain traffic, compared to the last successful baseline §25245508593 which contacted accounts.google.com, android.clients.google.com, and mtalk.google.com.

Probable Root Cause

A regression around or after 2026-05-03 in:

• Harness deferred-session state management — tail-scan window too short, or marker not persisted correctly across job boundaries, OR
• A change to the workflow initialization sequence that altered when/how the session is deferred

The "Prior session exited uncleanly" message points to a lingering stale session ID that may conflict with each new run's resume attempt.

Proposed Remediation

1. Investigate harness deferred-session logic in Claude Code v2.1.126 — specifically the tail-scan window and marker persistence between the pre-agent and agent jobs
2. Check git history around 2026-05-03 for changes to multi-device-docs-tester.lock.yml or shared harness initialization code
3. Short-term workaround: Modify the workflow to avoid session deferral, or add a fallback that starts a fresh session when the deferred marker is missing
4. Clean up stale session state for ID 6655b237-5666-42c3-b6bf-2e1473e87727

Success Criteria

• Multi-Device Docs Tester produces a successful conclusion on the next scheduled run
• No No deferred tool marker found errors in harness logs
• Playwright and Android device testing phase reached (Google domains visible in firewall logs)

References:

• Failed run (latest): §25479583239
• Last successful run (diff baseline): §25245508593
• Engine: Claude Code v2.1.126, claude-sonnet-4-6

Generated by [aw] Failure Investigator (6h) · ● 1M · ◷

• expires on May 14, 2026, 8:09 AM UTC