feat(llm-pi-ai): modelOverrides reshapes catalog models without replacing the catalog

A route's modelOverrides dict customizes individual installed-catalog
models — key = catalog model id, value = the same fields a models entry
takes — while the rest of the catalog keeps serving, which a models list
cannot express because declaring one replaces the served set. An
override becomes the catalog entry's configuration and resolves through
the existing entry path, so capacities, reasoningEfforts, compat, and
request-default semantics are identical to a models entry's. Unlike
Pi's config layer, which ignores unknown ids, every override that lands
nowhere is refused at the write that produced it: beside a models list,
on a hand-declared route, naming a model the catalog does not describe,
or smuggling an id through the schema's unknown-key tolerance.

packages/llm/llm-pi-ai/src/config.ts

@@ -22,7 +22,7 @@ import { MAX_TIMER_DELAY_MS } from '@deepseek-ai/dsh-timeout'
 import { normalizeApiKey, resolveRetryPolicy, RetryPolicySchema } from '@deepseek-ai/dsh-llm'
 import type { ResolvedRetryPolicy, RetryPolicyConfig } from '@deepseek-ai/dsh-llm'
 import { resolveRouteModels, SUPPORTED_THINKING_FORMATS, THINKING_LEVELS } from './catalog.ts'
-import type { PiAiCompatProfile, PiAiModelProfile, PiAiReasoningEfforts } from './catalog.ts'
+import type { PiAiCompatProfile, PiAiModelOverride, PiAiModelProfile, PiAiReasoningEfforts } from './catalog.ts'
 import { buildProvider, supportedProtocols } from './provider.ts'
 
 /** Default maximum idle interval while an adapter stream read is outstanding. */
@@ -34,7 +34,13 @@ export const DEFAULT_CONTEXT_WINDOW = 262_144
 /** Output capability assumed for a model neither configuration nor the catalog sizes. */
 export const DEFAULT_MAX_TOKENS = 32_768
 
-export type { PiAiCompatProfile, PiAiModelProfile, PiAiReasoningEfforts, PiAiThinkingFormat } from './catalog.ts'
+export type {
+  PiAiCompatProfile,
+  PiAiModelOverride,
+  PiAiModelProfile,
+  PiAiReasoningEfforts,
+  PiAiThinkingFormat,
+} from './catalog.ts'
 
 /** Configuration for one pi-ai provider route; the `providers` dict key IS the route. */
 export interface PiAiProviderProfile {
@@ -62,6 +68,15 @@ export interface PiAiProviderProfile {
    * unset fields from the installed model of the same id.
    */
   models?: PiAiModelProfile[]
+  /**
+   * Installed-catalog customizations by model id: each entry reshapes that
+   * one model with the same fields a {@link models} entry takes, while the
+   * rest of the catalog keeps serving untouched. Only meaningful on a catalog
+   * route with no `models` list — `models` already replaces the catalog, so
+   * an override beside it, on a route the catalog does not ship, or naming a
+   * model the catalog does not describe is refused rather than skipped.
+   */
+  modelOverrides?: Record<string, PiAiModelOverride>
   /**
    * Reasoning-dispatch switches for every `openai-completions` model on this
    * route; each model's own `compat` overrides per field. What neither sets
@@ -176,6 +191,15 @@ const modelProfile: z<PiAiModelProfile> = z.object({
   compat: compatProfile,
 })
 
+/** A {@link modelProfile} whose id lives in the `modelOverrides` dict key. */
+const modelOverride: z<PiAiModelOverride> = z.object({
+  name: z.string(),
+  contextWindow: z.number().step(1).min(1),
+  maxTokens: z.number().step(1).min(1),
+  reasoningEfforts: z.union([z.const(false), reasoningEfforts]),
+  compat: compatProfile,
+})
+
 const profile = z.object({
   apiKey: z.string().role('secret'),
   apiKeyEnv: z.string().role('credential-ref'),
@@ -183,6 +207,7 @@ const profile = z.object({
   api: z.union(supportedProtocols()),
   baseURL: z.string(),
   models: z.array(modelProfile),
+  modelOverrides: z.dict(modelOverride),
   compat: compatProfile,
   defaultContextWindow: z.number().step(1).min(1).default(DEFAULT_CONTEXT_WINDOW),
   defaultMaxTokens: z.number().step(1).min(1).default(DEFAULT_MAX_TOKENS),
@@ -291,6 +316,7 @@ export function resolveProfiles(
       ...source.api === undefined ? {} : { api: source.api },
       ...source.baseURL === undefined ? {} : { baseURL: source.baseURL },
       ...source.models === undefined ? {} : { models: source.models },
+      ...source.modelOverrides === undefined ? {} : { modelOverrides: source.modelOverrides },
       ...source.compat === undefined ? {} : { compat: source.compat },
       defaultContextWindow: source.defaultContextWindow ?? DEFAULT_CONTEXT_WINDOW,
       defaultMaxTokens: source.defaultMaxTokens ?? DEFAULT_MAX_TOKENS,