fix(types): derive agent llm.vendor union from @jambonz/schema

[davehorton]

Problem

The AgentLlm.vendor union in src/types/verbs.ts was hand-maintained and had drifted from the source of truth (the @jambonz/schema agent verb enum). It listed only 7 vendors and was missing baseten, azure-openai, groq, and huggingface — all valid at runtime (the @jambonz/llm adapter registry supports them) and present in the schema. The result: TypeScript rejected valid agent configs, forcing consumers into casts like vendor: 'baseten' as 'openai'.

The schema and the MCP server were both correct — only the SDK's hand-written type lagged.

Fix

Derive the vendor list from the schema instead of duplicating it by hand:

• scripts/gen-llm-vendors.mjs — reads llm.vendor.enum from @jambonz/schema's verbs/agent.schema.json and emits src/types/llm-vendors.generated.ts (a const tuple + derived LlmVendor type).
• AgentLlm.vendor now references the generated LlmVendor type.
• Wired gen:types into prebuild and pretypecheck, so published artifacts and CI always track the installed schema version. A new vendor in the schema flows into the types automatically on the next build.
• Exported LlmVendor and LLM_VENDORS for consumers (validation, UI dropdowns, etc.).
• The generated file is committed so fresh checkouts and tsc work without a codegen step.

Drift guard

Added a test in schema-drift.test.ts asserting the committed LLM_VENDORS equals the schema enum — catches a stale generated file if the schema dep is bumped without re-running gen:types. (The existing drift tests only compared property names, not enum values, which is how this slipped through.)

Verification

• npm run typecheck ✅ (regenerates via pretypecheck)
• npm run build ✅ — built .d.ts now exports all 11 vendors
• npm test ✅ 117 passing (was 116; +1 drift guard)

🤖 Generated with Claude Code