fix(model-resolver): respect UI model selection in agent initialization (#1158)

- Add uiSelectedModel parameter to resolveModelWithFallback()
- Update model resolution priority: UI Selection → Config Override → Fallback → System Default
- Pass config.model as uiSelectedModel in createBuiltinAgents()
- Fix ProviderModelNotFoundError when model is unset in config but selected in UI

src/shared/model-resolver.test.ts

@@ -113,7 +113,80 @@ describe("resolveModelWithFallback", () => {
     logSpy.mockRestore()
   })
 
-  describe("Step 1: Override", () => {
+  describe("Step 1: UI Selection (highest priority)", () => {
+    test("returns uiSelectedModel with override source when provided", () => {
+      // #given
+      const input: ExtendedModelResolutionInput = {
+        uiSelectedModel: "opencode/glm-4.7-free",
+        userModel: "anthropic/claude-opus-4-5",
+        fallbackChain: [
+          { providers: ["anthropic", "github-copilot"], model: "claude-opus-4-5" },
+        ],
+        availableModels: new Set(["anthropic/claude-opus-4-5", "github-copilot/claude-opus-4-5-preview"]),
+        systemDefaultModel: "google/gemini-3-pro",
+      }
+
+      // #when
+      const result = resolveModelWithFallback(input)
+
+      // #then
+      expect(result!.model).toBe("opencode/glm-4.7-free")
+      expect(result!.source).toBe("override")
+      expect(logSpy).toHaveBeenCalledWith("Model resolved via UI selection", { model: "opencode/glm-4.7-free" })
+    })
+
+    test("UI selection takes priority over config override", () => {
+      // #given
+      const input: ExtendedModelResolutionInput = {
+        uiSelectedModel: "opencode/glm-4.7-free",
+        userModel: "anthropic/claude-opus-4-5",
+        availableModels: new Set(["anthropic/claude-opus-4-5"]),
+        systemDefaultModel: "google/gemini-3-pro",
+      }
+
+      // #when
+      const result = resolveModelWithFallback(input)
+
+      // #then
+      expect(result!.model).toBe("opencode/glm-4.7-free")
+      expect(result!.source).toBe("override")
+    })
+
+    test("whitespace-only uiSelectedModel is treated as not provided", () => {
+      // #given
+      const input: ExtendedModelResolutionInput = {
+        uiSelectedModel: "   ",
+        userModel: "anthropic/claude-opus-4-5",
+        availableModels: new Set(["anthropic/claude-opus-4-5"]),
+        systemDefaultModel: "google/gemini-3-pro",
+      }
+
+      // #when
+      const result = resolveModelWithFallback(input)
+
+      // #then
+      expect(result!.model).toBe("anthropic/claude-opus-4-5")
+      expect(logSpy).toHaveBeenCalledWith("Model resolved via config override", { model: "anthropic/claude-opus-4-5" })
+    })
+
+    test("empty string uiSelectedModel falls through to config override", () => {
+      // #given
+      const input: ExtendedModelResolutionInput = {
+        uiSelectedModel: "",
+        userModel: "anthropic/claude-opus-4-5",
+        availableModels: new Set(["anthropic/claude-opus-4-5"]),
+        systemDefaultModel: "google/gemini-3-pro",
+      }
+
+      // #when
+      const result = resolveModelWithFallback(input)
+
+      // #then
+      expect(result!.model).toBe("anthropic/claude-opus-4-5")
+    })
+  })
+
+  describe("Step 2: Config Override", () => {
     test("returns userModel with override source when userModel is provided", () => {
       // #given
       const input: ExtendedModelResolutionInput = {
@@ -131,7 +204,7 @@ describe("resolveModelWithFallback", () => {
       // #then
       expect(result!.model).toBe("anthropic/claude-opus-4-5")
       expect(result!.source).toBe("override")
-      expect(logSpy).toHaveBeenCalledWith("Model resolved via override", { model: "anthropic/claude-opus-4-5" })
+      expect(logSpy).toHaveBeenCalledWith("Model resolved via config override", { model: "anthropic/claude-opus-4-5" })
     })
 
     test("override takes priority even if model not in availableModels", () => {
@@ -190,7 +263,7 @@ describe("resolveModelWithFallback", () => {
     })
   })
 
-  describe("Step 2: Provider fallback chain", () => {
+  describe("Step 3: Provider fallback chain", () => {
     test("tries providers in order within entry and returns first match", () => {
       // #given
       const input: ExtendedModelResolutionInput = {
@@ -317,7 +390,7 @@ describe("resolveModelWithFallback", () => {
     })
   })
 
-  describe("Step 3: System default fallback (no availability match)", () => {
+  describe("Step 4: System default fallback (no availability match)", () => {
     test("returns system default when no availability match found in fallback chain", () => {
       // #given
       const input: ExtendedModelResolutionInput = {

src/shared/model-resolver.ts

@@ -21,6 +21,7 @@ export type ModelResolutionResult = {
 }
 
 export type ExtendedModelResolutionInput = {
+	uiSelectedModel?: string
 	userModel?: string
 	fallbackChain?: FallbackEntry[]
 	availableModels: Set<string>
@@ -43,16 +44,23 @@ export function resolveModel(input: ModelResolutionInput): string | undefined {
 export function resolveModelWithFallback(
 	input: ExtendedModelResolutionInput,
 ): ModelResolutionResult | undefined {
-	const { userModel, fallbackChain, availableModels, systemDefaultModel } = input
+	const { uiSelectedModel, userModel, fallbackChain, availableModels, systemDefaultModel } = input
 
-	// Step 1: Override
+	// Step 1: UI Selection (highest priority - respects user's model choice in OpenCode UI)
+	const normalizedUiModel = normalizeModel(uiSelectedModel)
+	if (normalizedUiModel) {
+		log("Model resolved via UI selection", { model: normalizedUiModel })
+		return { model: normalizedUiModel, source: "override" }
+	}
+
+	// Step 2: Config Override (from oh-my-opencode.json)
 	const normalizedUserModel = normalizeModel(userModel)
 	if (normalizedUserModel) {
-		log("Model resolved via override", { model: normalizedUserModel })
+		log("Model resolved via config override", { model: normalizedUserModel })
 		return { model: normalizedUserModel, source: "override" }
 	}
 
-	// Step 2: Provider fallback chain (with availability check)
+	// Step 3: Provider fallback chain (with availability check)
 	if (fallbackChain && fallbackChain.length > 0) {
 		if (availableModels.size === 0) {
 			const connectedProviders = readConnectedProvidersCache()
@@ -91,7 +99,7 @@ export function resolveModelWithFallback(
 		log("No available model found in fallback chain, falling through to system default")
 	}
 
-	// Step 3: System default (if provided)
+	// Step 4: System default (if provided)
 	if (systemDefaultModel === undefined) {
 		log("No model resolved - systemDefaultModel not configured")
 		return undefined