[BUG] Auto-mode classifier permanently pinned to unavailable opus-4-8 pool; account missing Sonnet-5 classifier config (tengu_auto_mode_config.model absent)

Environment

• Claude Code 2.1.210 (native install, autoUpdates off), macOS (Darwin 25.4)
• Subscription auth (same org as unaffected colleagues), permissions.defaultMode: "auto"

Bug

In every session with auto mode enabled, all classified tool calls fail with:

claude-opus-4-8 is temporarily unavailable, so auto mode cannot determine the safety of Bash right now. ...

(claude-opus-4-8[1m] when the session main model is Fable 5.) This is continuous — weeks, not bursts — and the main loop works fine on the exact same model in the same session (one session billed ~$1.49 of opus-4-8 output while its own classifier reported opus-4-8 unavailable throughout). Read-only tools work; Bash (anything beyond deterministic allow rules), Edit/Write (even in-project), Agent, and Workflow are all blocked. The classifier model is validated once and pinned per session, so a session never recovers.

Root-cause evidence

• My freshly-fetched ~/.claude.json → cachedGrowthBookFeatures.tengu_auto_mode_config contains no model / modelByMainModel keys, so per the selection logic documented in #67542 the client falls back to the hardcoded opus-4-8(+[1m] for new-family mains) classifier — not the "classifier now defaults to Sonnet 5" behavior described in the 2.1.210 changelog.
• Colleagues in the same org are unaffected — presumably their cohort receives the Sonnet-5 classifier config, mine does not.
• CLAUDE_CODE_AUTO_MODE_MODEL=claude-sonnet-5 in settings env is ignored (verified: fresh session still pins the opus-4-8 classifier), matching the probe result in #67542.

Expected

• Classifier uses the Sonnet 5 default (or falls back to an available model instead of failing closed for the entire session), and/or CLAUDE_CODE_AUTO_MODE_MODEL is honored.

Request

• Move my account/org to the Sonnet-5 classifier config, or ship the classifier fallback.
• Either wire up or remove CLAUDE_CODE_AUTO_MODE_MODEL.

Related: #74351, #68437, #63819, #63959, #38537