[refactor] Move default provider ID functionality into provider definition

packages/types/src/__tests__/io-intelligence.test.ts

@@ -12,7 +12,7 @@ describe("IO Intelligence shared contract", () => {
 	it("registers the stable dynamic-provider identity and default model", () => {
 		expect(providerIdentifiers.ioIntelligence).toBe("io-intelligence")
 		expect(dynamicProviders).toContain(providerIdentifiers.ioIntelligence)
-		expect(getProviderDefaultModelId(providerIdentifiers.ioIntelligence)).toBe(ioIntelligenceDefaultModelId)
+		expect(getProviderDefaultModelId(providerIdentifiers.ioIntelligence, {})).toBe(ioIntelligenceDefaultModelId)
 	})
 
 	it("classifies the API key as secret and resolves the configured model", () => {

packages/types/src/__tests__/nanogpt.test.ts

@@ -14,7 +14,7 @@ describe("NanoGPT shared contract", () => {
 	it("registers the stable dynamic-provider identity and default model", () => {
 		expect(providerIdentifiers.nanogpt).toBe("nanogpt")
 		expect(dynamicProviders).toContain(providerIdentifiers.nanogpt)
-		expect(getProviderDefaultModelId(providerIdentifiers.nanogpt)).toBe(nanoGptDefaultModelId)
+		expect(getProviderDefaultModelId(providerIdentifiers.nanogpt, {})).toBe(nanoGptDefaultModelId)
 	})
 
 	it("classifies the API key as secret and resolves missing routing to auto", () => {

packages/types/src/__tests__/provider-default-model.test.ts

@@ -15,7 +15,7 @@ vi.mock("../provider-identifiers.js", async (importOriginal) => {
 import { providerIdentifiers } from "../provider-identifiers.js"
 import {
 	anthropicDefaultModelId,
-	getProviderDefaultModelId,
+	getZAiDefaultModelId,
 	internationalZAiDefaultModelId,
 	kimiCodeDefaultModelId,
 	mainlandZAiDefaultModelId,
@@ -24,49 +24,79 @@ import {
 	vscodeLlmDefaultModelId,
 	zooGatewayDefaultModelId,
 } from "../providers/index.js"
+import { getProviderDefaultModelId } from "../provider-settings.js"
+
+const zaiApiLineCases = [
+	["china_coding", "china"],
+	["china_api", "china"],
+	["international_coding", "international"],
+	["international_api", "international"],
+] as const
 
 describe("getProviderDefaultModelId", () => {
 	it("selects a static default through the canonical provider identifier", () => {
-		expect(getProviderDefaultModelId(providerIdentifiers.openrouter as ProviderName)).toBe(openRouterDefaultModelId)
+		expect(getProviderDefaultModelId(providerIdentifiers.openrouter as ProviderName, {})).toBe(
+			openRouterDefaultModelId,
+		)
 	})
 
 	it("triangulates static selection with another provider category", () => {
-		expect(getProviderDefaultModelId(providerIdentifiers.vscodeLm)).toBe(vscodeLlmDefaultModelId)
+		expect(getProviderDefaultModelId(providerIdentifiers.vscodeLm, {})).toBe(vscodeLlmDefaultModelId)
 	})
 
 	it("gives GitHub Copilot the same default as the VS Code LM provider", () => {
-		expect(getProviderDefaultModelId(providerIdentifiers.githubCopilot)).toBe(vscodeLlmDefaultModelId)
+		expect(getProviderDefaultModelId(providerIdentifiers.githubCopilot, {})).toBe(vscodeLlmDefaultModelId)
 	})
 
 	it("uses the canonical OpenAI Native default model", () => {
-		expect(getProviderDefaultModelId(providerIdentifiers.openaiNative)).toBe(openAiNativeDefaultModelId)
+		expect(getProviderDefaultModelId(providerIdentifiers.openaiNative, {})).toBe(openAiNativeDefaultModelId)
 	})
 
 	it.each([
 		[providerIdentifiers.kimiCode, kimiCodeDefaultModelId],
 		[providerIdentifiers.zooGateway, zooGatewayDefaultModelId],
 	])("preserves the %s default added on main", (provider, expectedModelId) => {
-		expect(getProviderDefaultModelId(provider)).toBe(expectedModelId)
+		expect(getProviderDefaultModelId(provider, {})).toBe(expectedModelId)
+	})
+
+	it.each(zaiApiLineCases)("resolves the %s Z.ai default through the provider definition", (zaiApiLine, region) => {
+		const expected = region === "china" ? mainlandZAiDefaultModelId : internationalZAiDefaultModelId
+
+		expect(getProviderDefaultModelId(providerIdentifiers.zai, { zaiApiLine })).toBe(expected)
 	})
 
-	it("preserves region-dependent defaults", () => {
-		// These defaults currently share the same model ID, so the assertions document
-		// both branches but cannot detect swapped ternary arms until the IDs diverge.
-		expect(getProviderDefaultModelId(providerIdentifiers.zai, { isChina: true })).toBe(mainlandZAiDefaultModelId)
-		expect(getProviderDefaultModelId(providerIdentifiers.zai)).toBe(internationalZAiDefaultModelId)
+	it("falls back to the international Z.ai default when the API line is unset", () => {
+		expect(getProviderDefaultModelId(providerIdentifiers.zai, {})).toBe(internationalZAiDefaultModelId)
+	})
+
+	describe("Z.ai region mapping", () => {
+		// Both regional catalogs currently share a default model ID, so inject
+		// distinct values to prove the mainland/international arms are not swapped.
+		const distinctDefaults = { china: "test-china-model", international: "test-international-model" }
+
+		it.each(zaiApiLineCases)("maps %s to the %s default", (zaiApiLine, region) => {
+			expect(getZAiDefaultModelId(zaiApiLine, distinctDefaults)).toBe(distinctDefaults[region])
+		})
+
+		it.each([undefined, null, "bogus"])(
+			"falls back to the international default for the invalid API line %s",
+			(zaiApiLine) => {
+				expect(getZAiDefaultModelId(zaiApiLine, distinctDefaults)).toBe(distinctDefaults.international)
+			},
+		)
 	})
 
 	it.each([providerIdentifiers.openai, providerIdentifiers.ollama, providerIdentifiers.lmstudio])(
 		"returns an empty default for custom or locally selected models from %s",
 		(provider) => {
-			expect(getProviderDefaultModelId(provider)).toBe("")
+			expect(getProviderDefaultModelId(provider, {})).toBe("")
 		},
 	)
 
 	it.each([providerIdentifiers.anthropic, providerIdentifiers.geminiCli, providerIdentifiers.fakeAi])(
 		"preserves the Anthropic fallback for %s",
 		(provider) => {
-			expect(getProviderDefaultModelId(provider)).toBe(anthropicDefaultModelId)
+			expect(getProviderDefaultModelId(provider, {})).toBe(anthropicDefaultModelId)
 		},
 	)
 })

packages/types/src/__tests__/provider-settings.test.ts

@@ -8,7 +8,7 @@ import {
 	providerSettingsSchemaDiscriminated,
 } from "../provider-settings.js"
 import { OpenAiCodexServiceTier, OpenAiServiceTier } from "../model.js"
-import { providerDefinitionList } from "../provider-settings/index.js"
+import { providerDefinitionList } from "../providers/index.js"
 
 describe("provider settings discriminated union", () => {
 	it("composes exactly one provider-specific definition for every provider", () => {
@@ -18,6 +18,16 @@ describe("provider settings discriminated union", () => {
 		expect(new Set(registeredProviders).size).toBe(providerNames.length)
 	})
 
+	it.each(providerDefinitionList.map((definition) => definition.apiProvider))(
+		"exposes a default model accessor for %s",
+		(apiProvider) => {
+			const definition = providerDefinitionList.find((candidate) => candidate.apiProvider === apiProvider)
+
+			expect(typeof definition?.getDefaultModelId).toBe("function")
+			expect(typeof definition?.getDefaultModelId({})).toBe("string")
+		},
+	)
+
 	it.each(providerNames)("accepts the %s provider branch", (apiProvider) => {
 		expect(providerSettingsSchemaDiscriminated.safeParse({ apiProvider }).success).toBe(true)
 	})

packages/types/src/provider-settings.ts

@@ -1,7 +1,7 @@
 import { z } from "zod"
 
-import { providerDefinitionList, type ProviderDefinition } from "./provider-settings/index.js"
-import { API_PROVIDER_FIELD, SETTINGS_SHAPE_FIELD } from "./provider-settings/common.js"
+import { providerDefinitionList, type ProviderDefinition } from "./providers/index.js"
+import { API_PROVIDER_FIELD, SETTINGS_SHAPE_FIELD } from "./providers/common.js"
 export {
 	DEFAULT_OPEN_AI_STRICT_TOOL_SCHEMAS,
 	OPEN_AI_CODEX_SERVICE_TIER_KEY,
@@ -14,7 +14,7 @@ export {
 	type NanoGptRoutingPreference,
 	zaiApiLineSchema,
 	type ZaiApiLine,
-} from "./provider-settings/index.js"
+} from "./providers/index.js"
 
 import { codebaseIndexProviderSchema } from "./codebase-index.js"
 import type { UnionToIntersection } from "./type-fu.js"
@@ -25,6 +25,7 @@ import {
 	type RetiredProviderIdentifier,
 } from "./provider-identifiers.js"
 import {
+	anthropicDefaultModelId,
 	anthropicModels,
 	basetenModels,
 	bedrockModels,
@@ -359,6 +360,14 @@ export function getModelId(settings: ProviderSettings): string | undefined {
 	return undefined
 }
 
+/**
+ * Get the provider's default model ID, ignoring any configured model selection.
+ * Used as a fallback while provider models are still loading.
+ */
+export function getProviderDefaultModelId(provider: ProviderName, settings: ProviderSettings): string {
+	return providerDefinitions[provider]?.getDefaultModelId(settings) ?? anthropicDefaultModelId
+}
+
 /**
  * ANTHROPIC_STYLE_PROVIDERS
  */