feat(providers): google/ model prefix, vendor routes on unknown prefixes, doctor ai@5 hint

[LinuxDevil]

Problem

resolveProvider('google/gemini-2.5-flash') and createAgent({ model: 'google/...' }) threw unrecognized provider 'google', because the only prefixes were openai, anthropic, openrouter, ollama, pi and mock. Competing SDKs accept any provider/model string. For any other vendor the error listed the prefixes and stopped there, without saying how to reach that vendor. Separately, an installed ai@5 (not supported) only got the generic peer-range failure in lousho doctor.

Fix

• google/ prefix: new GoogleProvider, built the same way as the OpenAI and Anthropic providers. It lazily loads the optional peer @ai-sdk/google through loadOptionalPeer(), pinned per ai major: ^1.2.0 for ai 4, ^3.0.0 for ai 6, ^4.0.0 for ai 7. It reads GOOGLE_GENERATIVE_AI_API_KEY. The peer is wired into:
  • the providerSpec PROVIDERS table, so it gets the missing-key error, the per-major install hint for LOUSHO_PEER_MISSING, env detection and the doctor checks for pairing and key
  • doctor --ping, which sends the key in the x-goog-api-key header
  • built-in registration, the barrel export, lousho init --provider google, specToAgent and the node-server provider detection
  • typings/optional-peers.d.ts, peerDependencies + peerDependenciesMeta.optional, and fallow ignoreDependencies
  • the Worker builds: in the /worker entry it is shimmed with a coded failure, and in the cloudflare adapter it stays external. Google is not a Worker provider, the same as ollama and pi.
• Unknown prefix: when nothing is a near-miss, the error now lists other ways to reach the vendor: openrouter/<vendor>/<model>, pi/<vendor>/<model> (only when pi-ai serves that vendor; a test checks the list against pi-ai's getProviders()), and createAgent({ provider: fromAiSdk(<vendor>('<model>')) }). A vendor that pi serves is never shown as a typo, so xai is no longer read as "did you mean pi". The [LOUSHO_PROVIDER_UNKNOWN] … (docs/errors.md#lousho_provider_unknown) help line is still appended, and its hint now mentions these routes.
• ai 5: lousho doctor fails peer.ai with "AI SDK v5 is not supported" and an upgrade hint: move to ai 6 or 7 and the matching @ai-sdk/* major. The README Installation section now states the supported ai majors.
• Docs: providers.md (Google, a new "Vendors without a prefix" section, the pairing table, the file-parts table, the ai 5 doctor note), installation.md pairing table, errors.md, CHANGELOG, and regenerated llms.txt, llms-full.txt and the api reports.

Verification

• npx tsc --noEmit, npm run lint, npm run build (including the Worker entry): clean
• npm run api:check, npm run docs:llms:check: up to date
• npx vitest run src/cli src/providers src/spec src/deploy src/createAgent.test.ts src/utils: 1599 passed, 4 skipped. The new tests cover:
  • the resolver with the peer mocked (GoogleProvider.test.ts) and absent (missingPeer.test.ts, the resolveProvider install hint)
  • the unknown-prefix messages: OpenRouter only, OpenRouter + pi, and factory-name sanitizing
  • the doctor checks for ai 5, @ai-sdk/google pairing and the Google ping
  • the init templates for google, and the Worker shim
• npm run typecheck:tests reports one error that already exists on main (src/tools/mcp/loadMcpTools.test.ts), not in this change.

🤖 Generated with Claude Code