docs(claude): journal fork identity-confusion hazard (2026-09-03)

[asachs01]

Summary

• A dispatched fork inherited full parent context and appears to have believed it WAS the parent session, acting on a different concurrent task under the shared bus/file identity.
• No fabrication -- every number the fork produced was independently verified correct. The failure is misattribution/duplication, not incorrect facts.
• Detection method that worked: resume the fork and have it self-audit its own tool-call history against its original directive.
• Correlation flagged as open hypothesis, not fact: 3 fork malfunctions today postdate last night's shared-binary refresh (e44bf20). Investigation task filed to maintainer (task_1788449111403_80624043).

Test plan

• Docs-only change (CLAUDE.md Learnings section), no code touched
• Isolated worktree used (shared checkout was dirty with unrelated in-progress work, not mine to disturb)
• Content independently reviewed for accuracy before commit (own incident, own memory records cross-checked)

Requested by boss for the shared journal.

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Summary by CodeRabbit

• Documentation
  • Updated guidance for investigating fork-related context confusion and duplicate output.
  • Clarified the distinction between fork exposure and non-fork subagents.
  • Replaced the unconfirmed shared-cause correlation with a same-day refutation based on verified evidence.
  • Clarified that repeated incidents on the same agent do not, by themselves, establish a shared underlying cause.

[coderabbitai]

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: 0bef1130-07a0-4028-929c-fde78b378b5e

📥 Commits

Reviewing files that changed from the base of the PR and between bbfe9c6 and e7c5bce.

📒 Files selected for processing (1)

• CLAUDE.md

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📝 Walkthrough

Walkthrough

Updated the 2026-09-03 fork identity-confusion learning. The entry now refutes the shared-binary correlation based on diff verification and attributes the incident to Claude-Code harness behavior.

Changes

Fork identity learning

Layer / File(s)	Summary
Refine fork identity confusion learning CLAUDE.md	Replaced the unconfirmed shared-binary correlation with a same-day refutation. The entry records that the five referenced PRs did not change fork, subagent, PTY, or context behavior, and treats recurrence on another agent as the meaningful shared-cause signal.

Estimated code review effort: 1 (Trivial) | ~2 minutes

Merge Risk: ⚪ Minimal · up to e7c5b

This updates a documented learning and does not change runtime behavior. No current merge-readiness risk remains.

Suggested reviewers: grandamenium

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the documentation change. It identifies the Claude documentation scope, the fork identity-confusion hazard, and the incident date.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

Full details: Docstring Coverage

Explanation

No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0 files. (1 skipped: 1 unsupported.)

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch murph/journal-fork-identity-confusion

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