MAESTRO: Implement model selection for OpenCode moderator - Task 3.1

- Add customModel field to ModeratorConfig type for storing selected model
- Update NewGroupChatModal to pass agentConfig.model through moderatorConfig
- Update App.tsx handleCreateGroupChat to accept customModel parameter
- Update spawnModeratorSynthesis to pass sessionCustomModel from moderatorConfig
- Update initial moderator spawn to pass sessionCustomModel for both spawns
- Verify modelArgs config produces correct --model flag in arguments

This enables users to select a custom model when creating a group chat,
and ensures the selected model is applied when spawning the OpenCode moderator.

src/main/group-chat/group-chat-router.ts

@@ -452,6 +452,7 @@ ${message}`;
 			});
 			const configResolution = applyAgentConfigOverrides(agent, baseArgs, {
 				agentConfigValues,
+				sessionCustomModel: chat.moderatorConfig?.customModel,
 				sessionCustomArgs: chat.moderatorConfig?.customArgs,
 				sessionCustomEnvVars: chat.moderatorConfig?.customEnvVars,
 			});
@@ -849,7 +850,9 @@ export async function routeModeratorResponse(
 
 				// Apply SSH wrapping if configured for this session
 				if (sshStore && matchingSession?.sshRemoteConfig) {
-					console.log(`[GroupChat:Debug] Applying SSH wrapping for participant ${participantName}...`);
+					console.log(
+						`[GroupChat:Debug] Applying SSH wrapping for participant ${participantName}...`
+					);
 					const sshWrapped = await wrapSpawnWithSsh(
 						{
 							command: spawnCommand,
@@ -1149,6 +1152,7 @@ Review the agent responses above. Either:
 	});
 	const configResolution = applyAgentConfigOverrides(agent, baseArgs, {
 		agentConfigValues,
+		sessionCustomModel: chat.moderatorConfig?.customModel,
 		sessionCustomArgs: chat.moderatorConfig?.customArgs,
 		sessionCustomEnvVars: chat.moderatorConfig?.customEnvVars,
 	});

src/renderer/App.tsx

@@ -8394,6 +8394,7 @@ You are taking over this conversation. Based on the context above, provide a bri
 				customPath?: string;
 				customArgs?: string;
 				customEnvVars?: Record<string, string>;
+				customModel?: string;
 			}
 		) => {
 			const chat = await window.maestro.groupChat.create(name, moderatorAgentId, moderatorConfig);

src/renderer/components/NewGroupChatModal.tsx

@@ -163,15 +163,18 @@ export function NewGroupChatModal({
 
 	// Build moderator config from state
 	const buildModeratorConfig = useCallback((): ModeratorConfig | undefined => {
-		const hasConfig = customPath || customArgs || Object.keys(customEnvVars).length > 0;
+		const customModelValue = agentConfig.model;
+		const hasConfig =
+			customPath || customArgs || Object.keys(customEnvVars).length > 0 || customModelValue;
 		if (!hasConfig) return undefined;
 
 		return {
 			customPath: customPath || undefined,
 			customArgs: customArgs || undefined,
 			customEnvVars: Object.keys(customEnvVars).length > 0 ? customEnvVars : undefined,
+			customModel: customModelValue || undefined,
 		};
-	}, [customPath, customArgs, customEnvVars]);
+	}, [customPath, customArgs, customEnvVars, agentConfig]);
 
 	const handleCreate = useCallback(() => {
 		if (name.trim() && selectedAgent) {
@@ -351,9 +354,7 @@ export function NewGroupChatModal({
 								>
 									{availableTiles.map((tile) => {
 										const isBeta =
-											tile.id === 'codex' ||
-											tile.id === 'opencode' ||
-											tile.id === 'factory-droid';
+											tile.id === 'codex' || tile.id === 'opencode' || tile.id === 'factory-droid';
 										return (
 											<option key={tile.id} value={tile.id}>
 												{tile.name}

src/shared/group-chat-types.ts

@@ -73,6 +73,8 @@ export interface ModeratorConfig {
 	customArgs?: string;
 	/** Custom environment variables */
 	customEnvVars?: Record<string, string>;
+	/** Custom model selection (e.g., 'ollama/qwen3:8b') */
+	customModel?: string;
 	/** SSH remote config for remote execution */
 	sshRemoteConfig?: {
 		enabled: boolean;