[Bug] Fable 5 bio classifier blocks innocuous academic statistics terms (组学, spatial transcriptomics)

Bug description

Claude Fable 5's bio safety classifier produces false positives on standard academic terminology used in statistical methodology research. Simply including terms like "组学" (Chinese for "-omics") or "spatial transcriptomics" in a prompt — with no dangerous or specific biological content — immediately triggers a Usage Policy refusal.

This affects researchers working on statistical methods for biological data, who never touch actual biological protocols, lab procedures, or anything remotely dual-use. The classifier appears to pattern-match on surface-level keywords without understanding context.

Reproduction steps

1. Open Claude Code (or claude.ai web) with Fable 5 selected
2. Send a prompt containing "spatial transcriptomics" or "组学" in a statistical methods context — e.g., "I'm developing a statistical method for spatial transcriptomics data analysis"
3. Observe the Usage Policy refusal

Expected behavior

These are standard academic terms appearing in thousands of published papers. A statistics researcher discussing methodology should not be blocked.

Actual behavior

Immediate refusal:

API Error: Claude Code is unable to respond to this request, which appears to violate our Usage Policy.

Observations

• The same prompts work fine on Opus 4.6 and Sonnet 4.6 — this is purely a Fable 5 classifier issue
• Chinese language prompts ("组学") may have an even lower trigger threshold than English equivalents, suggesting the classifier is undertrained on non-English academic vocabulary
• This affects the web interface (claude.ai) as well, not just Claude Code
• The user is a Statistics PhD candidate working on statistical methodology — no biology lab work, no protocols, no dual-use content whatsoever

Impact

Fable 5 is currently unusable for anyone in biostatistics, bioinformatics, computational biology, or any field that references biological data types in a methods context. This is a significant portion of the academic research community.

Suggested fix

The bio classifier should distinguish between:

• Discussing statistical/computational methods that operate on biological data (safe)
• Providing specific biological protocols, synthesis instructions, or dangerous procedures (appropriately blocked)

Environment

• Platform: macOS (Darwin 25.4.0)
• Claude Code version: latest
• Model: claude-fable-5
• Also reproducible on claude.ai web interface