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.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