The LLM seam and its provider adapters. The interface package (llm) owns the abstract service, the content-block vocabulary, and the stream-chunk assembler; the adapters are concrete implementations that register on ctx.llm. All product packages.

Package	Role	ctx key
`llm/`	Abstract LLM service + content-block vocabulary + chunk assembler	`ctx.llm`
`llm-deepseek/`	DeepSeek API adapter (hand-rolled fetch/SSE)	(registers on `ctx.llm`)
`llm-pi-ai/`	DeepSeek adapter via `@earendil-works/pi-ai` (design twin)	(registers on `ctx.llm`)

The interface lives at llm/llm/; adapters are flat siblings under the group. A new provider adapter joins here and registers on ctx.llm without touching the interface. See twin LLM adapters for why two adapters exist.