[MODEL] Opus 4.6 corrupted production data, ignored verification rules and memory

Preflight Checklist

• [x] I have searched existing issues for similar behavior reports
• [x] This report does NOT contain sensitive information (API keys, passwords, etc.)

Type of Behavior Issue

Claude modified files I didn't ask it to modify

What You Asked Claude to Do

1. Update a name remap across pipeline files
2. Update a name remap in SQL lookup files
3. Verify a name in all database tables
4. Fix inconsistent formatting in code
5. Pick specific commits to production
6. Trace data flow to place a remap correctly
7. Normalize values in source and output pipelines
8. Summarize session tasks

What Claude Actually Did

1. Updated wrong columns multiple times, used replace_all corrupting data
2. Used replace_all corrupting input and output values, had to revert
3. Declared "verified" without querying the database
4. Introduced inconsistent formatting that wasn't there before
5. Pushed entire branch instead of specific commits, locked branches with worktrees
6. Guessed column names, placed remap where column didn't exist yet
7. Added normalize lines that didn't work, couldn't explain why
8. couldn't follow simple formatting after 15+ corrections, kept trying to include PII

Expected Behavior

1. Edit the correct column, one line at a time
2. Edit one line at a time, never use replace_all
3. Query the database after every change
4. Match existing formatting, don't introduce new formats
5. Pick only the requested commits, don't lock branches
6. Check the schema before writing code
7. Trace the data flow, place the remap where it actually takes effect
8. Follow simple instructions on the first try

Files Affected

Permission Mode

Accept Edits was OFF (manual approval required)

Can You Reproduce This?

Yes, every time with the same prompt

Steps to Reproduce

_No response_

Claude Model

Opus

Relevant Conversation

Impact

Critical - Data loss or corrupted project

Claude Code Version

Claude Code 2.1.74, running Opus 4.6 (1M context).

Platform

Anthropic API

Additional Context

_No response_