[Bug]: Usage shows Claude Mythos 5.2 and Fable 5.2 as Unpriced#33715

Before submitting

• I searched existing issues and did not find a duplicate.
• I included enough detail to reproduce or investigate the problem.

Area

apps/server (usage pricing)

Steps to reproduce

1. Run Claude turns on Claude Mythos 5.2 (claude-mythos-5-2) and Claude Fable 5.2 (claude-fable-5-2).
2. Open the Usage page.

Expected behavior

Both models are priced from LiteLLM rates, like Mythos 5.1 and Fable 5.1 are.

Actual behavior

Usage for both models has no price ("Unpriced").

Two separate causes, from reading apps/server/src/usage/usagePricing.ts and UsageService.ts and running the same lookup against today's LiteLLM model_prices_and_context_window.json:

Mythos 5.2: no rate the lookup can match. LiteLLM has no bare claude-mythos-5-2 key yet. It only has Bedrock-style keys: anthropic.claude-mythos-5-2, us./eu./global./us-gov.anthropic.claude-mythos-5-2, and bedrock/us-gov-*/anthropic.claude-mythos-5-2. parseRateTable only adds aliases by stripping the part before the last /, so the best it can get is anthropic.claude-mythos-5-2. That is never claude-mythos-5-2. resolveRate then misses, and Mythos 5.2 stays unpriced however often the rates refresh. (Mythos 5.1 works only because LiteLLM has a bare claude-mythos-5-1 row.)

Fable 5.2: old rates kept for up to 24 hours. LiteLLM added a bare claude-fable-5-2 row on 2026-11-09 (BerriAI/litellm#50715), and the current table resolves it directly. But RATES_TTL_MS is 24h, and the cached rate file on disk is reused until it expires. So installs that fetched rates before that commit keep showing Fable 5.2 as unpriced for up to a day. This happens with every new model launch.

Suggested fix

• Let aliasing also strip Bedrock's dotted prefixes (anthropic., plus region prefixes like us.anthropic.). Prefer the first-party anthropic row when there is one, and keep the existing rule that leaves an alias unpriced when the candidate rates disagree. LiteLLM's anthropic.claude-mythos-5-2 costs $8/M input and $40/M output.
• Refetch rates early, before the 24h TTL, when a scan finds a model with no rate in the cached table. Limit it with the existing RATES_REFRESH_FLOOR_MS.

Impact

Minor bug or occasional failure. Spend on the newest Claude models is missing from Usage totals.

Version or commit

Checked against main on 2026-11-10.

Workaround

Fable 5.2 prices once the cached rates expire, or after a forced rate refresh. Mythos 5.2 has no workaround short of a custom rate override.