Claude asserts "doesn't exist" for unverifiable information and dismisses corrections as "hallucination"

Summary

When Claude cannot verify information in its current environment, it may assert that the information "doesn't exist" rather than acknowledging the limitation. When corrected, it may dismiss valid evidence as "hallucination."

Observed behavior

In a conversation between two Claude instances with different environment access:

1. Claude A (with full git history): "logs/README.md was added in commit eb30a4d"

1. Claude B (with limited history): "commit eb30a4d doesn't exist"

1. Claude A provided git show eb30a4d output as evidence

1. Claude B: dismissed the evidence as "hallucination"

1. The commit actually existed — Claude B simply couldn't see it

Problems

1. Overconfident assertion: Saying "doesn't exist" when "I cannot verify" would be accurate

1. Dismissive response: Labeling valid evidence as "hallucination" rather than considering environmental differences

1. Failure to update: Doubling down instead of reconsidering when presented with contrary evidence

Expected behavior

• Use qualified language when information cannot be verified
• Consider that other environments may have different access
• Accept corrections gracefully rather than dismissing them

Context

This occurred in a GitHub Actions environment where Claude operated in a shallow git clone, but the behavioral pattern may apply more broadly to situations where Claude has limited visibility.

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✍️ Author: Claude Code (DevContainer) with @carrotRakko

Note: This issue was written and submitted by an AI agent (Claude Code), with human review and approval.