feat(models): host-neutral embed/rerank/vision defaults — no default names a machine

[kh0pper]

Why

This is sub-project D1 of the grackle decommission; Kevin is selling grackle. Today every Crow instance embeds through grackle's GPU. That happens because servers/memory/embeddings.js falls back to the hard-coded "grackle-embed", rerank.js defaults to "grackle-rerank", and the smart-router's vision route is baked to "grackle-vision". A default that names one machine is a product bug.

Measured 2026-09-24: crow already serves the same model, Qwen3-Embedding-0.6B (Q8, 1024 dimensions, last-token pooling), at 100.118.41.122:8004. Embedding the same text on both servers gives cosine 0.999, so switching needs no re-embed.

What

• servers/shared/provider-task.js (new): a task-based default resolver. Embed resolves in this order:
  1. CROW_EMBED_PROVIDER env;
  2. the embed_provider setting;
  3. the lowest-id enabled provider that has a model tagged embed or embedding;
  4. otherwise null.
     Rerank follows the same order with its own env, setting and tags (rerank/score, since real reranker rows are tagged score). Results are cached 30 s per task and setting, and the env is checked before the cache. A DB failure gives null, never a named host.
• embeddings.js / rerank.js:
  • They use the resolver, and use the matching model rather than models[0].
  • rerank now also reads rows that exist only in the DB.
  • null degrades to full-text search or no rerank, as a missing provider does today.
• smart-router.js: DEFAULT_ROUTES.vision is tierDefault("vision", null) (the new CROW_SMART_ROUTER_VISION override). Otherwise it picks an image-capable enabled provider, and its image-capable model.
• Also updated: the Settings AI-profiles hint, the four manual smoke scripts (now env-driven and host-neutral), and the docs (EN + ES).
• Unchanged: embed_provider and rerank_provider stay out of the fleet sync allowlist.

No behaviour change at deploy

I read crow, grackle and black-swan's live provider tables read-only. Each has exactly one enabled row tagged embed (grackle-embed) and one tagged score (grackle-rerank), and no setting. So embed and rerank resolve to the same providers as today until the ops step adds crow-embed. Vision improves: image turns stop going to the dead grackle-vision row and reach the multimodal crow-local 35B.

Process

• Spec: docs/superpowers/specs/2026-09-24-host-neutral-model-defaults-design.md
• Plan: docs/superpowers/plans/2026-09-24-host-neutral-model-defaults.md. Two adversarial review rounds:
  • round 1 found the score tag, the DB-only rerank rows and a test-helper mismatch;
  • round 2 approved.
• Build: 3 subagent-driven tasks, each reviewed.
• Final review: Ready with fixes. It found the any-model-match vs models[0] issue; fixed and re-reviewed.
• Tests: full suite 5147 pass / 0 fail (Node 24).

After merge (ops, not in this PR)

1. Add a crow-embed provider row on crow (it syncs) and on r4, and set embed_provider=crow-embed.
2. Repoint r4's CROW_EMBED_PROVIDER / EMBED_HOST.
3. Disable the dead grackle-rerank and grackle-vision rows.
4. grackle-embed retires with grackle.