[Bug] Claude Fable 5 classifier false positives on fintech signing/enforcement terminology

Bug Description
False positive #2 — Claude Fable 5 classifier triggered on fintech platform code audit Session context: auditing a multi-tenant fintech payment platform (BIPCircle, a stablecoin payment rail). Reviewing environment variable configuration across Cloud Run services. Trigger: a grep search for SIGNING_SURFACE_ENFORCEMENT across the codebase, followed by a gcloud run services describe command checking staging environment variables. Likely cause: the term "SIGNING_SURFACE_ENFORCEMENT" pattern-matching as cryptographic/security terminology. In context it is a feature flag controlling which payment surfaces are permitted to initiate signing flows — standard fintech access control, not security research. Expected behaviour: Fable 5 continues the session. Actual behaviour: fell back to Opus 4.8 mid-session. This is the second false positive in the same BIPCircle codebase within one session. Standard fintech terminology (signing, enforcement, allowlist, surface) appears to be systematically triggering the classifier on legitimate commercial payment platform work.

Environment Info

• Platform: darwin
• Terminal: Apple_Terminal
• Version: 2.1.170
• Feedback ID: 1b62f0be-15c7-4129-8ef7-4241ec21f5c5

Errors

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