feat(tui): add busy status indicator during processing

docs/plans/state.json

@@ -5745,6 +5745,17 @@
         "docs/plans/state.json"
       ],
       "test_status": "pnpm test:run src/gateway/handlers/handlers.test.ts + pnpm typecheck passing"
+    },
+    "minimal-tui-busy-status-indicator": {
+      "status": "completed",
+      "date": "2026-02-19",
+      "updated": "2026-02-19",
+      "summary": "Added an explicit busy status indicator in minimal TUI while Flynn is processing requests, including a spinner and cancel hint, with safe teardown before streamed output/tool logs so the terminal no longer appears frozen between prompt submit and response.",
+      "files_modified": [
+        "src/frontends/tui/minimal.ts",
+        "docs/plans/state.json"
+      ],
+      "test_status": "pnpm test:run src/frontends/tui/minimal.test.ts passing"
     }
   },
   "overall_progress": {

src/frontends/tui/minimal.ts

@@ -73,6 +73,7 @@ export interface MinimalTuiConfig {
 
 export class MinimalTui {
   private static readonly CTRL_C_EXIT_WINDOW_MS = 1_500;
+  private static readonly BUSY_FRAMES = ['-', '\\', '|', '/'] as const;
   private rl: readline.Interface | null = null;
   private running = false;
   private totalUsage: TokenUsage = { inputTokens: 0, outputTokens: 0 };
@@ -81,6 +82,9 @@ export class MinimalTui {
   private activePromptCancel: (() => void) | null = null;
   private activeOperationCancel: (() => void) | null = null;
   private keypressHandler: ((char: string, key: readline.Key) => void) | null = null;
+  private busyTimer: NodeJS.Timeout | null = null;
+  private busyFrameIndex = 0;
+  private busyActive = false;
   private verbose = false;
   private lastCtrlCAtMs = 0;
 
@@ -182,10 +186,53 @@ export class MinimalTui {
     }).join(', ');
   }
 
+  private startBusyIndicator(): void {
+    if (this.busyActive) {
+      return;
+    }
+
+    this.busyActive = true;
+    const render = () => {
+      const frame = MinimalTui.BUSY_FRAMES[this.busyFrameIndex];
+      const message = `${formatPrompt('thinking')}${colors.gray}${frame} Flynn is thinking... (Esc to cancel)${colors.reset}`;
+      if (process.stdout.isTTY) {
+        process.stdout.write(`\r${message}`);
+      } else {
+        console.log(message);
+      }
+    };
+
+    render();
+    if (!process.stdout.isTTY) {
+      return;
+    }
+
+    this.busyTimer = setInterval(() => {
+      this.busyFrameIndex = (this.busyFrameIndex + 1) % MinimalTui.BUSY_FRAMES.length;
+      render();
+    }, 125);
+  }
+
+  private stopBusyIndicator(): void {
+    if (!this.busyActive) {
+      return;
+    }
+    this.busyActive = false;
+    this.busyFrameIndex = 0;
+    if (this.busyTimer) {
+      clearInterval(this.busyTimer);
+      this.busyTimer = null;
+    }
+    if (process.stdout.isTTY) {
+      process.stdout.write('\r\x1b[K');
+    }
+  }
+
   private handleToolEvent(event: ToolUseEvent): void {
     if (!this.verbose) {
       return;
     }
+    this.stopBusyIndicator();
     if (event.type === 'start') {
       const label = this.formatToolName(event.tool);
       const argsStr = event.args ? ` (${this.formatToolArgs(event.args)})` : '';
@@ -1268,6 +1315,7 @@ export class MinimalTui {
     process.stdout.write(
       `\n${colors.orange}${colors.bold}Flynn${colors.reset} ${colors.gray}[${formatMessageTime(Date.now())}]${colors.reset}\n`,
     );
+    this.startBusyIndicator();
 
     try {
       // Use agent if available (supports tool loop)
@@ -1283,6 +1331,7 @@ export class MinimalTui {
         };
         const response = await this.config.agent.process(content);
         this.activeOperationCancel = null;
+        this.stopBusyIndicator();
         const rendered = renderMarkdown(response);
         console.log(rendered);
         console.log();
@@ -1295,6 +1344,7 @@ export class MinimalTui {
       // Try streaming if available
       if (this.config.modelClient.chatStream) {
         let fullContent = '';
+        let streamStarted = false;
         let cancelRequested = false;
         this.activeOperationCancel = () => {
           if (cancelRequested) {
@@ -1313,10 +1363,18 @@ export class MinimalTui {
             break;
           }
           if (event.type === 'content' && event.content) {
+            if (!streamStarted) {
+              streamStarted = true;
+              this.stopBusyIndicator();
+            }
             process.stdout.write(event.content);
             fullContent += event.content;
           }
           if (event.type === 'fallback_warning' && event.fallbackReason) {
+            if (!streamStarted) {
+              streamStarted = true;
+              this.stopBusyIndicator();
+            }
             console.warn('\n⚠ Using fallback model');
           }
           if (event.type === 'done' && event.usage) {
@@ -1342,6 +1400,7 @@ export class MinimalTui {
           system: this.config.systemPrompt,
         });
         this.activeOperationCancel = null;
+        this.stopBusyIndicator();
 
         const rendered = renderMarkdown(response.content);
         console.log(rendered);
@@ -1353,9 +1412,11 @@ export class MinimalTui {
         this.config.session.addMessage({ role: 'assistant', content: response.content });
       }
     } catch (error) {
+      this.stopBusyIndicator();
       console.error('Error:', error instanceof Error ? error.message : error);
       console.log();
     } finally {
+      this.stopBusyIndicator();
       this.activeOperationCancel = null;
     }
   }