fix: hint message render order and harness/runtime disambiguation

- isHint check now comes after isExec (matching preview branch) so
  exec messages always render as magenta, not gray
- When a project has both runtimes and harnesses and no flag is given,
  show a clear error listing both --runtime and --harness options

Author: jesseturner21

src/cli/commands/invoke/action.ts

@@ -86,6 +86,19 @@ export async function handleInvoke(context: InvokeContext, options: InvokeOption
     if (isHarnessInvoke) {
       return handleHarnessInvoke(project, targetState, targetConfig, selectedTargetName, options);
     }
+
+    if (harnessEntries.length > 0 && project.runtimes.length > 0 && !options.agentName) {
+      const runtimeNames = project.runtimes.map(a => a.name);
+      const harnessNames = harnessEntries.map(h => h.name);
+      return {
+        success: false,
+        error: new ValidationError(
+          `Project has both runtimes and harnesses. Specify one:\n` +
+            `  --runtime: ${runtimeNames.join(', ')}\n` +
+            `  --harness: ${harnessNames.join(', ')}`
+        ),
+      };
+    }
   }
 
   if (project.runtimes.length === 0) {

src/cli/tui/screens/invoke/InvokeScreen.tsx

@@ -48,14 +48,14 @@ function formatConversation(
     // Skip empty assistant messages (placeholder before streaming starts)
     if (msg.role === 'assistant' && !msg.content) continue;
 
-    if (msg.isHint) {
-      lines.push({ text: msg.content, color: 'gray' });
-    } else if (msg.role === 'user' && msg.isExec) {
+    if (msg.role === 'user' && msg.isExec) {
       lines.push({ text: msg.content, color: 'magenta' });
     } else if (msg.role === 'user') {
       lines.push({ text: `> ${msg.content}`, color: 'blue' });
     } else if (msg.isExec) {
       lines.push({ text: msg.content });
+    } else if (msg.isHint) {
+      lines.push({ text: msg.content, color: 'gray' });
     } else if (msg.parts && msg.parts.length > 0) {
       // Rich AGUI rendering: render each part with distinct visual treatment
       for (const part of msg.parts) {