Opus 4.6 dated-snapshot route audit

Opened: 2026-04-21 (Sprint 10 Day-2, per PM ratification at PM-Waggle-OS/decisions/2026-04-21-sprint-10-task-1.2-ratified-opus46-deferred.md). Policy: trigger on first caller trip — do NOT audit proactively in Sprint 10. Related: Sprint 10 Task 1.2 (Sonnet route repair, commit a09831e merge), migration note at ops/litellm/README.md §Sprint-10-Task-1.2.

Why this file exists

Sprint 10 Task 1.2 repaired the claude-sonnet-4-6 LiteLLM alias which had been routing to a dated snapshot (-20250514) that was never a valid Claude API ID for the Sonnet 4.6 family. Investigation of the config showed the adjacent claude-opus-4-6 alias uses the same dated-snapshot pattern (-20250610) and may have the same latent defect.

Per Anthropic's live models overview (re-fetched 2026-04-21), the Opus 4.6 family Claude API ID is claude-opus-4-6 (plain alias, no dated suffix). The -20250610 suffix is not explicitly listed in the docs for the 4.6 family — it could be a valid but unlisted snapshot, or it could be a broken legacy entry that nobody's called in a while.

PM policy (2026-04-21): no speculative audit. The potential defect affects only callers that explicitly call claude-opus-4-6, and Sprint 10 doesn't exercise that path (judges run claude-opus-4-7 + Sonnet + tri-vendor). Opening a speculative audit PR in Sprint 10 distracts from the locked operational queue. Instead, this ticket tracks the concern and authorizes a targeted audit if/when a runtime caller trips on it.

Caller map (as of 2026-04-21 commit `6cf7554`)

claude-opus-4-6 or claude-opus-4.6 is referenced in 22 files (grep result, waggle-os repo only — zero hits in hive-mind):

Config + docs: litellm-config.yaml, ops/litellm/README.md, benchmarks/harness/config/models.json, docs/specs/PROMPT-ASSEMBLER-V4.md, EVAL-RESULTS-V5.md.
Runtime routes: packages/server/src/local/routes/providers.ts, packages/server/src/local/routes/anthropic-proxy.ts, packages/server/src/local/routes/litellm.ts.
Frontend: apps/web/src/lib/providers.ts, apps/web/src/components/os/apps/ChatWindowInstance.tsx, apps/web/src/lib/spawn-agent-helpers.test.ts.
Agent + eval: packages/agent/src/cost-tracker.ts, packages/agent/tests/eval/prompt-assembler-v5-eval.ts, packages/agent/tests/eval/prompt-assembler-eval.ts, packages/agent/tests/model-tier.test.ts, packages/server/tests/local-mode.test.ts.
Scripts + historical: scripts/evolution-hypothesis{,-resume,-rejudge-gemini}.mjs, docs/.evolution-hypothesis-2026-04-14T08-04-57/03-judge-scores.json.
Tauri artifacts: app/src-tauri/resources/service.js{,.map} (build outputs — not source).

Most of these are configuration, UI model-picker strings, or historical eval artifacts. Active runtime paths are:

packages/server/src/local/routes/providers.ts
packages/server/src/local/routes/anthropic-proxy.ts
packages/server/src/local/routes/litellm.ts
packages/agent/src/cost-tracker.ts
apps/web/src/lib/providers.ts + consumer ChatWindowInstance.tsx

If a user in the UI picks "Claude Opus 4.6" in the model selector and runs a chat turn, the call flows UI → providers.ts → Anthropic route → LiteLLM → anthropic/claude-opus-4-6-20250610. That's the trip surface.

Trigger condition

Open a PR with title

fix(litellm): audit claude-opus-4-6 dated-snapshot route

when any of the following happen:

A user reports a 404 / model_not_found when picking Opus 4.6 in the Waggle UI model picker, OR
A test or eval harness run fails with the LiteLLM error signature litellm.NotFoundError: AnthropicException - ... model: claude-opus-4-6-20250610, OR
An operational readiness check (e.g., pre-Stage-2 full-suite vitest) explicitly exercises the Opus 4.6 route and returns the same signature.

Fix shape (if triggered)

Should mirror the Sprint 10 Task 1.2 Sonnet repair:

Re-fetch Anthropic docs. Confirm the current live Claude API ID for Opus 4.6 (expected: plain claude-opus-4-6; the -20250610 dated snapshot is expected to be either valid-but-decommissioned or invented).
Edit litellm-config.yaml — repoint the primary claude-opus-4-6 alias + the legacy alias anthropic/claude-opus-4.6 to the plain anthropic/claude-opus-4-6.
Add a section to ops/litellm/README.md under the existing Sprint-10 Task-1.2 header documenting the triggering call, the date, and the verification docs URL.
Extend scripts/smoke-sonnet-route.mjs into scripts/smoke-anthropic-route.mjs (parameterized by model) OR add an Opus-specific smoke script — pick the cheaper path based on whether other Anthropic routes are expected to need similar audits (Haiku 4.5 is already correctly dated per the current config).
Commit + PR with commit message referencing this doc as root-cause memo and the Sprint 10 Task 1.2 migration note as the repair template.

Non-actions (per PM policy)

Do NOT pre-audit. Do NOT open a Sprint 10 PR for this.
Do NOT remove the claude-opus-4-6 alias from the config — a UI-picker reference still exists. If broken, repair is right; removal is scope-creep.
Do NOT expand the audit to other Anthropic aliases without a specific caller-trip signal. claude-haiku-4-5-20251001 for example has a valid dated suffix per the public docs.

Ticket stays open until either the trigger fires (fix) or until the Opus 4.6 alias is retired from all callers (close as obsolete). No forced Sprint slot.

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