[MODEL] Claude ignores its own previously-documented project rule across later actions in the same session

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• [x] I have searched existing issues for similar behavior reports
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Type of Behavior Issue

Claude modified files I didn't ask it to modify

What You Asked Claude to Do

Repeated failure to follow a self-documented, explicit project rule across multiple actions in the same session. The missing migration blocked a real deployment attempt by a colleague on the project (not the user I was working with), who had to diagnose the failure, write the missing migration file himself, and commit the fix. Claude did not identify or fix the root cause — a human did.

What I observed as the underlying issue

This wasn't a one-off slip caused by not knowing the rule — the rule existed, in writing, produced by Claude itself, in the same session, in the same repository. The failure was in applying a known rule consistently across a long sequence of agentic actions, not in knowledge or reasoning ability.

When asked to fix this "for real," Claude's first instinct was to build a local enforcement mechanism (a git pre-commit hook) to mechanically block the mistake from recurring. The user pushed back correctly: a hook only patches the symptom for this one project. It does not address why an explicit, self-authored rule was not followed in the first place, and it would not transfer to any other rule, project, or session.

What Claude Actually Did

This wasn't a one-off slip caused by not knowing the rule — the rule existed, in writing, produced by Claude itself, in the same session, in the same repository. The failure was in applying a known rule consistently across a long sequence of agentic actions, not in knowledge or reasoning ability.

Expected Behavior

When asked to fix this "for real," Claude's first instinct was to build a local enforcement mechanism (a git pre-commit hook) to mechanically block the mistake from recurring. The user pushed back correctly: a hook only patches the symptom for this one project. It does not address why an explicit, self-authored rule was not followed in the first place, and it would not transfer to any other rule, project, or session.

Files Affected

Permission Mode

Accept Edits was ON (auto-accepting changes)

Can You Reproduce This?

Yes, every time with the same prompt

Steps to Reproduce

_No response_

Claude Model

Sonnet

Relevant Conversation

Impact

Critical - Data loss or corrupted project

Claude Code Version

sonet 5 hi

Platform

Anthropic API

Additional Context

_No response_