[claude-sonnet-4-6] Data Loss — Claude Code Overwrote User's Confluence Page Despite Explicit Instruction

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

Other unexpected behavior

What You Asked Claude to Do

I was using Claude Code (Claude Sonnet 4.6) to help organise my business
planning system across Notion, Miro, and Confluence. My Confluence page (Page
ID: 655361, titled "Daily tasks") contained 3–5 months of daily business logs
— day-by-day entries from November 2025 to June 2026.

My explicit instruction (Session ID: 60f54c6f-9e56-4d84-8e2d-fd97dada23ac,
Line 289):

▎ "i want you to keep all what i have already, but i want you to parallally
▎ build a system for me"

I asked Claude to BUILD NEW templates alongside my existing pages — not touch
or replace anything already there.

What Claude Actually Did

1. Read Confluence page 655361 ("Daily tasks") — my personal daily business

log

1. Without warning or confirmation, overwrote it with entirely new content

called "Daily Ritual SOP" — attempted multiple times (session lines 382, 394,
396, 399, 402, 407, 410, 414, 419)

1. When I discovered the deletion and asked for restoration, Claude said:

"Result: Daily tasks | OK" — confirming successful recovery

1. The recovery was false — Claude had only captured ~4000 characters of

stripped text from the original before overwriting. Weeks of daily log entries
beyond that point were permanently lost

1. When I pressed further, Claude admitted the data beyond that cutoff was

gone

Expected Behavior

1. Keep Confluence page 655361 completely untouched
2. Create a NEW separate page for the "Daily Ritual SOP" content
3. Never overwrite existing user data without explicit confirmation
4. If partial recovery only — be upfront immediately, not after being pressed

Files Affected

Modified (destructively):
  - Confluence page 655361 — "Daily tasks" (3–5 months of daily business logs,  
  irreversibly overwritten)

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

Sonnet

Relevant Conversation

User (Line 289): "i want you to keep all what i have already, but i want you 
  to parallally build a system for me"                                          
  
  Claude (Lines 382–419): Proceeded to overwrite Confluence page 655361 with PUT
   requests replacing content with "Daily Ritual SOP"       
                                                                                
  User (Line 445): "i want you to keep that whole page which was there as it is"

  Claude confirmed: "Result: Daily tasks | OK" — false confirmation. Only 4703  
  characters recovered out of months of original content

Impact

Critical - Data loss or corrupted project

Claude Code Version

2.1.131 (from session metadata)

Platform

Anthropic API

Additional Context

The false recovery confirmation is a separate issue from the overwrite —
Claude should never confirm successful restoration without verifying the
restored content matches the original

• Session log file available on request: