fix(coding-agent): apply modelOverrides to extension providers

closes #6367

packages/coding-agent/CHANGELOG.md

@@ -20,6 +20,7 @@
 - Fixed the edit tool schema to allow model-invented extra replacement fields instead of rejecting otherwise valid edits ([#6278](https://github.com/earendil-works/pi/issues/6278)).
 - Fixed new session resets to clear cached label timestamps ([#6354](https://github.com/earendil-works/pi/issues/6354)).
 - Fixed auto-retry for Bun fetch socket-drop errors reported as `socket connection was closed`, so transient provider disconnects do not end headless runs without retrying ([#6431](https://github.com/earendil-works/pi/issues/6431)).
+- Fixed `models.json` `modelOverrides` to apply to extension-registered provider models ([#6367](https://github.com/earendil-works/pi/issues/6367)).
 
 ### Removed
 

packages/coding-agent/docs/models.md

@@ -139,7 +139,7 @@ Set `api` at provider level (default for all models) or model level (override pe
 | `headers` | Custom headers (see value resolution below) |
 | `authHeader` | Set `true` to add `Authorization: Bearer <apiKey>` automatically |
 | `models` | Array of model configurations |
-| `modelOverrides` | Per-model overrides for built-in models on this provider |
+| `modelOverrides` | Per-model overrides for built-in or extension-registered models on this provider |
 
 For providers with `models`, non-built-in provider configs need `baseUrl` and an `api` value at either provider or model level. `apiKey` is not required to load the file: models become available when auth is configured through `/login`/`auth.json`, CLI `--api-key`, or provider `apiKey`. If no auth is configured, the models load but stay unavailable in `/model` and `--list-models`.
 
@@ -293,7 +293,7 @@ Merge semantics:
 
 ## Per-model Overrides
 
-Use `modelOverrides` to customize specific built-in models without replacing the provider's full model list.
+Use `modelOverrides` to customize built-in models and matching extension-registered models without replacing the provider's full model list.
 
 ```json
 {
@@ -314,10 +314,10 @@ Use `modelOverrides` to customize specific built-in models without replacing the
 }
 ```
 
-`modelOverrides` supports these fields per model: `name`, `reasoning`, `input`, `cost` (partial), `contextWindow`, `maxTokens`, `headers`, `compat`.
+`modelOverrides` supports these fields per model: `name`, `reasoning`, `thinkingLevelMap`, `input`, `cost` (partial), `contextWindow`, `maxTokens`, `headers`, `compat`.
 
 Behavior notes:
-- `modelOverrides` are applied to built-in provider models.
+- `modelOverrides` are applied to built-in provider models and matching extension-registered provider models.
 - Unknown model IDs are ignored.
 - You can combine provider-level `baseUrl`/`headers` with `modelOverrides`.
 - Overriding `name` changes model matching and secondary detail text only; the footer and primary model lists continue to show the model `id`.

packages/coding-agent/src/core/model-registry.ts

@@ -353,6 +353,7 @@ export class ModelRegistry {
 	private models: Model<Api>[] = [];
 	private providerRequestConfigs: Map<string, ProviderRequestConfig> = new Map();
 	private modelRequestHeaders: Map<string, Record<string, string>> = new Map();
+	private configModelOverrides: Map<string, Map<string, ModelOverride>> = new Map();
 	private registeredProviders: Map<string, ProviderConfigInput> = new Map();
 	private loadError: string | undefined = undefined;
 	readonly authStorage: AuthStorage;
@@ -406,6 +407,7 @@ export class ModelRegistry {
 			modelOverrides,
 			error,
 		} = this.modelsJsonPath ? this.loadCustomModels(this.modelsJsonPath) : emptyCustomModelsResult();
+		this.configModelOverrides = modelOverrides;
 
 		if (error) {
 			this.loadError = error;
@@ -459,6 +461,15 @@ export class ModelRegistry {
 		});
 	}
 
+	private getConfiguredModelOverride(providerName: string, modelId: string): ModelOverride | undefined {
+		return this.configModelOverrides.get(providerName)?.get(modelId);
+	}
+
+	private applyConfiguredModelOverride(providerName: string, model: Model<Api>): Model<Api> {
+		const modelOverride = this.getConfiguredModelOverride(providerName, model.id);
+		return modelOverride ? applyModelOverride(model, modelOverride) : model;
+	}
+
 	/** Merge custom models into built-in list by provider+id (custom wins on conflicts). */
 	private mergeCustomModels(builtInModels: Model<Api>[], customModels: Model<Api>[]): Model<Api>[] {
 		const merged = [...builtInModels];
@@ -921,9 +932,14 @@ export class ModelRegistry {
 			// Parse and add new models
 			for (const modelDef of config.models) {
 				const api = modelDef.api || config.api;
-				this.storeModelHeaders(providerName, modelDef.id, modelDef.headers);
+				const modelOverride = this.getConfiguredModelOverride(providerName, modelDef.id);
+				const headers =
+					modelDef.headers || modelOverride?.headers
+						? { ...modelDef.headers, ...modelOverride?.headers }
+						: undefined;
+				this.storeModelHeaders(providerName, modelDef.id, headers);
 
-				this.models.push({
+				const model = this.applyConfiguredModelOverride(providerName, {
 					id: modelDef.id,
 					name: modelDef.name,
 					api: api as Api,
@@ -938,6 +954,7 @@ export class ModelRegistry {
 					headers: undefined,
 					compat: modelDef.compat,
 				} as Model<Api>);
+				this.models.push(model);
 			}
 
 			// Apply OAuth modifyModels if credentials exist (e.g., to update baseUrl)

packages/coding-agent/test/model-registry.test.ts

@@ -8,7 +8,7 @@ import type {
 	Model,
 	OpenAICompletionsCompat,
 } from "@earendil-works/pi-ai/compat";
-import { getApiProvider } from "@earendil-works/pi-ai/compat";
+import { getApiProvider, getSupportedThinkingLevels } from "@earendil-works/pi-ai/compat";
 import { getOAuthProvider } from "@earendil-works/pi-ai/oauth";
 import { afterEach, beforeEach, describe, expect, test, vi } from "vitest";
 import { AuthStorage } from "../src/core/auth-storage.ts";
@@ -938,6 +938,63 @@ describe("ModelRegistry", () => {
 			expect(registry.getProviderDisplayName("oauth-provider")).toBe("OAuth Provider");
 		});
 
+		test("modelOverrides apply to dynamically registered provider models", async () => {
+			writeRawModelsJson({
+				"extension-provider": {
+					modelOverrides: {
+						"extension-model": {
+							name: "Overridden Extension Model",
+							thinkingLevelMap: {
+								off: null,
+								minimal: null,
+								low: null,
+								medium: null,
+								xhigh: "max",
+							},
+							headers: { "x-model-override": "enabled" },
+						},
+					},
+				},
+			});
+
+			const registry = ModelRegistry.create(authStorage, modelsJsonPath);
+			registry.registerProvider("extension-provider", {
+				baseUrl: "https://provider.test/v1",
+				apiKey: "test-key",
+				api: "openai-completions",
+				models: [
+					{
+						id: "extension-model",
+						name: "Extension Model",
+						reasoning: true,
+						input: ["text"],
+						cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
+						contextWindow: 128000,
+						maxTokens: 4096,
+					},
+				],
+			});
+
+			const model = registry.find("extension-provider", "extension-model");
+			expect(model).toBeDefined();
+			if (!model) {
+				throw new Error("extension model was not registered");
+			}
+			expect(model.name).toBe("Overridden Extension Model");
+			expect(model.thinkingLevelMap).toEqual({
+				off: null,
+				minimal: null,
+				low: null,
+				medium: null,
+				xhigh: "max",
+			});
+			expect(getSupportedThinkingLevels(model)).toEqual(["high", "xhigh"]);
+			expect(await registry.getApiKeyAndHeaders(model)).toMatchObject({
+				ok: true,
+				headers: { "x-model-override": "enabled" },
+			});
+		});
+
 		test("stored API key env propagates to request auth and resolves headers", async () => {
 			authStorage.set("cloudflare-ai-gateway", {
 				type: "api_key",