feat(llm): interrogate a draft provider endpoint for its models

Once a pi-ai route became a declaration rather than a catalog lookup,
adding an OpenAI-compatible gateway meant knowing its model ids up
front. Most such endpoints publish that list at `GET /models`, but no
seam operation could ask: every one is keyed by a registered provider
route, and the provider being added has no route, no stored profile,
and no stored credential — the endpoint and key are values in a form.

Interrogation is therefore keyed by settings namespace, which a
configuration surface already holds from the configurable-provider
directory. `registerModelDiscovery` offers it per namespace,
`discoverModels` asks, and the request carries the draft itself. The
reply is candidates, not a catalog: every field but the id is optional
because most listings disclose nothing else, and adopting one is a
settings write like any other. Nothing here reads or writes settings or
credentials, so `settings.yaml` still decides what a route serves.

`llm.discoverModels` carries the same draft over the wire. Its apiKey is
the third and last payload a secret may ride, and it is never stored,
logged, or echoed; every refusal folds into `model-discovery-failed`,
naming the endpoint asked but never the credential offered.

The pi-ai side is a plain GET for OpenAI-compatible protocols only —
their listing shape is the one gateways, self-hosted servers, and the
official endpoints agree on. Others say so, sending the user to
hand-entry rather than reporting a guessed shape as an empty provider.
The reply is read under a four-megabyte ceiling held on the bytes
actually received, because the endpoint is a URL the user typed.

packages/cordis/tool-cordis/src/api-catalog.ts

@@ -428,6 +428,18 @@ export const SERVICE_API: readonly ServiceApiEntry[] = [
         signature: 'listConfigurableProviders(): LlmConfigurableProvider[]',
         jsDoc: '/**\n * List every declared configurable provider, registered or dormant.\n * @returns detached directory entries in declaration order.\n */',
       },
+      {
+        signature: 'registerModelDiscovery( settingsNs: string, discover: (request: LlmModelDiscoveryRequest) => Promise<readonly LlmDiscoveredModel[]>, ): () => void',
+        jsDoc: '/**\n * Offer to interrogate provider endpoints on behalf of the settings\n * namespace this plugin owns. The namespace is the key because that is what\n * a configuration surface already holds from the configurable-provider\n * directory, and because a provider being *added* has no route to name yet.\n * Disposed with the fiber.\n * @param settingsNs - the namespace whose profiles this discovery serves.\n * @param discover - interrogates one endpoint; must honor `request.signal`.\n * @returns the disposer that withdraws the offer.\n */',
+      },
+      {
+        signature: 'listModelDiscoveryNamespaces(): string[]',
+        jsDoc: '/**\n * List the settings namespaces that can interrogate a provider endpoint, so\n * a surface can offer the action only where it will work.\n * @returns the namespaces in registration order.\n */',
+      },
+      {
+        signature: 'async discoverModels( settingsNs: string, request: LlmModelDiscoveryRequest, ): Promise<LlmDiscoveredModel[]>',
+        jsDoc: '/**\n * Interrogate one provider endpoint for the models it advertises. The\n * request describes a draft, not a stored route, so nothing here reads or\n * writes settings or credentials — the caller owns both, and the reply is\n * candidate metadata a surface may offer for adoption.\n * @param settingsNs - namespace whose registered discovery serves this draft.\n * @param request - the endpoint, protocol, and one-shot credential to use.\n * @returns the advertised models, deduplicated in endpoint order.\n */',
+      },
       {
         signature: 'providerRetryPolicy(provider: string): ResolvedRetryPolicy',
         jsDoc: '/**\n * Resolve the retry policy captured when one provider route was registered.\n * @param provider - registered provider route to inspect.\n * @returns the provider-owned policy, with normal defaults already resolved.\n */',
@@ -2097,6 +2109,10 @@ export const TYPE_API: readonly TypeApiEntry[] = [
     name: 'LlmConfigurableProvider',
     declaration: 'export interface LlmConfigurableProvider {\n    provider: string;\n    displayName: string;\n    settingsNs: string;\n    settingsPath: readonly string[];\n}',
   },
+  {
+    name: 'LlmDiscoveredModel',
+    declaration: 'export interface LlmDiscoveredModel {\n    id: string;\n    name?: string;\n    contextWindow?: number;\n    maxTokens?: number;\n}',
+  },
   {
     name: 'LlmFailure',
     declaration: 'export interface LlmFailure {\n    readonly message: string;\n    readonly code: string;\n    readonly status?: number;\n    readonly providerRetryAfterMs?: number;\n    readonly requestId?: ProviderRequestId;\n}',
@@ -2105,6 +2121,10 @@ export const TYPE_API: readonly TypeApiEntry[] = [
     name: 'LlmModelContext',
     declaration: 'export interface LlmModelContext {\n    contextWindow: number;\n}',
   },
+  {
+    name: 'LlmModelDiscoveryRequest',
+    declaration: 'export interface LlmModelDiscoveryRequest {\n    baseURL: string;\n    api?: string;\n    apiKey?: string;\n    signal?: AbortSignal;\n}',
+  },
   {
     name: 'LlmModelInfo',
     declaration: 'export interface LlmModelInfo {\n    provider: string;\n    id: string;\n    name: string;\n    description?: string;\n}',