feat(acp): advertise and switch llm models

docs/core-data-structures/core.md

@@ -150,6 +150,30 @@ One model call is a fully-assembled `GenerateOptions`. The adapter answers with
 
 Source: [`packages/llm/llm/src/types.ts`](../../packages/llm/llm/src/types.ts)
 
+Provider and model discovery uses small provider-neutral descriptors. A model catalog is advisory: routing still keys on a registered provider, and an adapter may accept unlisted model ids.
+
+```ts type-equiv
+interface LlmProviderInfo {
+  /** Provider route key used by {@link GenerateOptions.provider}. */
+  id: string
+  /** Human-readable provider name for selectors and diagnostics. */
+  name: string
+}
+```
+
+```ts type-equiv
+interface LlmModelInfo {
+  /** Provider route that owns this model entry. */
+  provider: string
+  /** Model id passed to {@link GenerateOptions.model}. */
+  id: string
+  /** Human-readable model name for selectors. */
+  name: string
+  /** Optional user-facing distinction from otherwise similar models. */
+  description?: string
+}
+```
+
 ```ts type-equiv
 interface GenerateOptions {
   /** Registered provider route selecting the adapter instance. */