[MODEL] Repetitive "belt-and-suspenders" idiom across unrelated sessions

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

No specific prompt — this is a cross-session observation. The pattern appeared across 7 unrelated Claude Code sessions in 7 different projects (Solidity work, infra automation, terminal/dotfiles setup, etc.).

What Claude Actually Did

Across 7 unrelated Claude Code sessions in 7 different projects, the model produced the idiom "belt-and-suspenders" 25 times. Every instance fills the same semantic slot — describing redundant/defensive safety measures.

Examples from transcripts:

• "normalize txHash before DB lookups as belt-and-suspenders"
• "the explicit endpoint allowlist is belt-and-suspenders"
• "If you want belt-and-suspenders, before the 30k tx we could…"
• "set confirm-close-surface=true too, so you also get a prompt for active processes. Some redundancy with undo (belt-and-suspenders)"

Expected Behavior

Use varied language for describing redundant safety measures — "defense in depth", "extra guard", "additional safeguard", or plain English — rather than reflexively reaching for "belt-and-suspenders" as the canonical phrase.

Files Affected

Permission Mode

Accept Edits was ON (auto-accepting changes)

Can You Reproduce This?

Sometimes (intermittent)

Steps to Reproduce

Ask Claude Code to suggest a defensive coding measure or any "extra precaution" pattern. The phrase will tend to surface in responses across unrelated domains (blockchain, infra, shell config, etc.).

Claude Model

Opus

Relevant Conversation

Sample excerpts (real, from transcripts):
- "normalizes txHash before DB lookups as belt-and-suspenders"
- "Adding the explicit endpoint allowlist is belt-and-suspenders"
- "If you want belt-and-suspenders, wiring it in is one extra constructor argument"
- "set `confirm-close-surface = true` too, so you also get a prompt for active processes. Some redundancy with undo."

Impact

Low - Minor inconvenience

Claude Code Version

2.1.148

Platform

Anthropic API

Additional Context

Not in any system prompt or project CLAUDE.md (verified by grep). Reads like an RL-trained idiom that scored well in security/defensive-coding contexts and now generalizes too broadly to any "extra precaution" framing. Similar shape to the OpenAI "goblins" reward-bleed pattern described in https://openai.com/index/where-the-goblins-came-from/