diff --git a/extensions/remote-control/spike-cc.ts b/extensions/remote-control/spike-cc.ts
new file mode 100644
index 0000000..d4c9e52
--- /dev/null
+++ b/extensions/remote-control/spike-cc.ts
@@ -0,0 +1,219 @@
+#!/usr/bin/env ts-node
+
+/**
+ * Phase 0.5 Spike — tmux Control Mode
+ * 
+ * This is a throwaway PoC to evaluate tmux control mode as an alternative
+ * to pipe-pane for streaming pi output.
+ * 
+ * Usage:
+ *   npm run spike-cc
+ *   
+ * Then in another terminal:
+ *   tmux attach -t pi-cc  # Verify parallel attach works
+ */
+
+import { spawn, ChildProcess } from 'child_process';
+import * as readline from 'readline';
+
+const SESSION_NAME = 'pi-cc';
+
+interface Stats {
+  outputEvents: number;
+  bytesReceived: number;
+  otherEvents: number;
+  startTime: number;
+}
+
+const stats: Stats = {
+  outputEvents: 0,
+  bytesReceived: 0,
+  otherEvents: 0,
+  startTime: Date.now(),
+};
+
+/**
+ * Decode tmux's octal-escaped output format.
+ * Example: "hello\\012world" -> "hello\nworld"
+ */
+function decodeOctalEscapes(input: string): Buffer {
+  const chunks: number[] = [];
+  let i = 0;
+  
+  while (i < input.length) {
+    if (input[i] === '\\' && i + 3 < input.length) {
+      // Check if next 3 chars are octal digits
+      const octalStr = input.substring(i + 1, i + 4);
+      if (/^[0-7]{3}$/.test(octalStr)) {
+        const charCode = parseInt(octalStr, 8);
+        chunks.push(charCode);
+        i += 4;
+        continue;
+      }
+    }
+    
+    // Regular character
+    chunks.push(input.charCodeAt(i));
+    i++;
+  }
+  
+  return Buffer.from(chunks);
+}
+
+/**
+ * Parse a control mode notification line.
+ */
+function parseNotification(line: string): { type: string; data: string } | null {
+  if (!line.startsWith('%')) {
+    return null;
+  }
+  
+  const spaceIdx = line.indexOf(' ');
+  if (spaceIdx === -1) {
+    return { type: line.substring(1), data: '' };
+  }
+  
+  return {
+    type: line.substring(1, spaceIdx),
+    data: line.substring(spaceIdx + 1),
+  };
+}
+
+/**
+ * Handle a %output notification.
+ */
+function handleOutputEvent(data: string): void {
+  // Format: %output %<pane-id> <value>
+  const parts = data.split(' ', 2);
+  if (parts.length < 2) {
+    console.error('[spike-cc] Invalid %output format:', data);
+    return;
+  }
+  
+  const paneId = parts[0]; // e.g., "%1"
+  const escapedValue = parts[1];
+  
+  // Decode octal escapes and write to stdout
+  const decoded = decodeOctalEscapes(escapedValue);
+  
+  stats.outputEvents++;
+  stats.bytesReceived += decoded.length;
+  
+  // Write to stdout (this is our streaming output)
+  process.stdout.write(decoded);
+}
+
+/**
+ * Main control mode loop.
+ */
+function runControlMode(): void {
+  console.error('[spike-cc] Starting tmux control mode spike...');
+  console.error('[spike-cc] Session name:', SESSION_NAME);
+  console.error('[spike-cc] Creating detached session first...');
+  
+  // Step 1: Create detached session with pi
+  const createSession = spawn('tmux', [
+    'new-session',
+    '-d',
+    '-s', SESSION_NAME,
+    '-x', '120',
+    '-y', '40',
+    'pi'
+  ]);
+  
+  createSession.on('close', (code) => {
+    if (code !== 0) {
+      console.error('[spike-cc] Failed to create session, code:', code);
+      console.error('[spike-cc] (This is OK if session already exists)');
+    }
+    
+    // Step 2: Attach in control mode
+    console.error('[spike-cc] Attaching in control mode...');
+    console.error('[spike-cc] ---------------------------------------------');
+    console.error('[spike-cc] Pi output will stream below (raw bytes).');
+    console.error('[spike-cc] Stats will be written to stderr every 10s.');
+    console.error('[spike-cc] To attach normally: tmux attach -t', SESSION_NAME);
+    console.error('[spike-cc] ---------------------------------------------');
+    
+    const tmuxControl = spawn('tmux', ['-C', 'attach', '-t', SESSION_NAME], {
+      stdio: ['pipe', 'pipe', 'pipe'],
+    });
+    
+    // Keep stdin open (don't send EOF)
+    // This prevents tmux from thinking the control client disconnected
+    
+    // Read control mode output line by line
+    const rl = readline.createInterface({
+      input: tmuxControl.stdout,
+      crlfDelay: Infinity,
+    });
+    
+    rl.on('line', (line) => {
+      const notification = parseNotification(line);
+      
+      if (!notification) {
+        // Not a notification, probably command response
+        return;
+      }
+      
+      if (notification.type === 'output') {
+        handleOutputEvent(notification.data);
+      } else if (notification.type === 'exit') {
+        console.error('\n[spike-cc] Received %exit, shutting down...');
+        process.exit(0);
+      } else {
+        // Other events (layout-change, window-add, etc.)
+        stats.otherEvents++;
+        // Log first few for debugging
+        if (stats.otherEvents <= 5) {
+          console.error(`[spike-cc] Event: %${notification.type}`);
+        }
+      }
+    });
+    
+    tmuxControl.stderr.on('data', (data) => {
+      console.error('[spike-cc] tmux stderr:', data.toString());
+    });
+    
+    tmuxControl.on('close', (code) => {
+      console.error('\n[spike-cc] tmux process exited, code:', code);
+      printFinalStats();
+      process.exit(code || 0);
+    });
+    
+    // Stats reporter
+    const statsInterval = setInterval(() => {
+      printStats();
+    }, 10000);
+    
+    // Cleanup on exit
+    process.on('SIGINT', () => {
+      console.error('\n[spike-cc] Caught SIGINT, cleaning up...');
+      clearInterval(statsInterval);
+      tmuxControl.kill();
+      printFinalStats();
+      process.exit(0);
+    });
+  });
+}
+
+function printStats(): void {
+  const elapsed = ((Date.now() - stats.startTime) / 1000).toFixed(1);
+  console.error(`\n[spike-cc] === Stats @ ${elapsed}s ===`);
+  console.error(`[spike-cc]   Output events: ${stats.outputEvents}`);
+  console.error(`[spike-cc]   Bytes received: ${stats.bytesReceived}`);
+  console.error(`[spike-cc]   Other events: ${stats.otherEvents}`);
+  console.error(`[spike-cc]   Rate: ${(stats.outputEvents / parseFloat(elapsed)).toFixed(2)} events/s`);
+}
+
+function printFinalStats(): void {
+  const elapsed = ((Date.now() - stats.startTime) / 1000).toFixed(1);
+  console.error('\n[spike-cc] === Final Stats ===');
+  console.error(`[spike-cc]   Total time: ${elapsed}s`);
+  console.error(`[spike-cc]   Output events: ${stats.outputEvents}`);
+  console.error(`[spike-cc]   Bytes received: ${stats.bytesReceived}`);
+  console.error(`[spike-cc]   Other events: ${stats.otherEvents}`);
+}
+
+// Run
+runControlMode();
diff --git a/package.json b/package.json
index 480c749..4d6fb94 100644
--- a/package.json
+++ b/package.json
@@ -17,7 +17,8 @@
   "scripts": {
     "lint": "biome check --write .",
     "lint:check": "biome check .",
-    "prepare": "node .husky/install.mjs"
+    "prepare": "node .husky/install.mjs",
+    "spike-cc": "npx -y ts-node extensions/remote-control/spike-cc.ts"
   },
   "devDependencies": {
     "@biomejs/biome": "^2.4.12",
diff --git a/test-spike-cc.sh b/test-spike-cc.sh
new file mode 100755
index 0000000..ac1964b
--- /dev/null
+++ b/test-spike-cc.sh
@@ -0,0 +1,172 @@
+#!/bin/bash
+# Test Protocol for Phase 0.5 Control Mode Spike
+
+set -e
+
+SESSION="pi-cc"
+LOG_FILE="/tmp/spike-cc-test-$(date +%s).log"
+DURATION=300  # 5 minutes
+
+echo "=== Phase 0.5 Control Mode Test Protocol ==="
+echo "Session: $SESSION"
+echo "Log: $LOG_FILE"
+echo "Duration: ${DURATION}s (5 minutes)"
+echo ""
+
+# Clean up any existing session
+tmux kill-session -t "$SESSION" 2>/dev/null || true
+
+echo "[1/6] Starting spike-cc in background..."
+cd "$(dirname "$0")"
+npm run spike-cc > "$LOG_FILE" 2>&1 &
+SPIKE_PID=$!
+echo "  Spike PID: $SPIKE_PID"
+sleep 3
+
+# Check if spike is still running
+if ! kill -0 $SPIKE_PID 2>/dev/null; then
+    echo "  ERROR: Spike process died!"
+    tail -50 "$LOG_FILE"
+    exit 1
+fi
+
+echo "  ✓ Spike running"
+echo ""
+
+echo "[2/6] Verifying session exists..."
+if ! tmux has-session -t "$SESSION" 2>/dev/null; then
+    echo "  ERROR: Session $SESSION not found!"
+    kill $SPIKE_PID 2>/dev/null
+    exit 1
+fi
+echo "  ✓ Session exists"
+echo ""
+
+echo "[3/6] Testing parallel tmux attach (critical P-2 requirement)..."
+echo "  Opening a 10-second tmux attach in background..."
+(tmux attach -t "$SESSION" 2>&1 | head -20 > /tmp/spike-parallel-attach.log) &
+ATTACH_PID=$!
+sleep 5
+
+if ! kill -0 $ATTACH_PID 2>/dev/null; then
+    echo "  ✓ Attach completed (expected for non-interactive)"
+else
+    echo "  ✓ Attach still running"
+    kill $ATTACH_PID 2>/dev/null || true
+fi
+
+# Check if spike is still running after parallel attach
+if ! kill -0 $SPIKE_PID 2>/dev/null; then
+    echo "  ERROR: Spike died during parallel attach!"
+    tail -50 "$LOG_FILE"
+    exit 1
+fi
+echo "  ✓ Control mode survived parallel attach"
+echo ""
+
+echo "[4/6] Triggering alternate-screen failure mode..."
+echo "  Sending /settings command..."
+tmux send-keys -t "$SESSION" "/settings" Enter
+sleep 2
+
+# Navigate in settings (arrow keys)
+echo "  Navigating in settings menu..."
+tmux send-keys -t "$SESSION" Down Down Up
+sleep 1
+
+# Exit settings (Escape or q)
+echo "  Exiting settings..."
+tmux send-keys -t "$SESSION" Escape
+sleep 2
+
+echo "  ✓ Alternate-screen sequence complete"
+echo ""
+
+# Check if spike is still receiving output
+echo "[5/6] Verifying stream still active after alternate-screen..."
+echo "  Sending test prompt..."
+tmux send-keys -t "$SESSION" "echo 'STREAM_TEST_AFTER_SETTINGS_$(date +%s)'" Enter
+sleep 2
+
+# Check recent output for our test string
+if tail -100 "$LOG_FILE" | grep -q "STREAM_TEST_AFTER_SETTINGS"; then
+    echo "  ✓ Stream still active! Control mode survived alternate-screen."
+else
+    echo "  WARNING: Test string not found in recent output."
+    echo "  This could mean a lag or the test was too fast."
+    echo "  Checking if spike is still running..."
+    if kill -0 $SPIKE_PID 2>/dev/null; then
+        echo "  ✓ Spike process still alive"
+    else
+        echo "  ERROR: Spike process died!"
+        tail -50 "$LOG_FILE"
+        exit 1
+    fi
+fi
+echo ""
+
+echo "[6/6] Running for full 5-minute duration..."
+START_TIME=$(date +%s)
+NEXT_REPORT=$((START_TIME + 60))
+
+while true; do
+    CURRENT_TIME=$(date +%s)
+    ELAPSED=$((CURRENT_TIME - START_TIME))
+    
+    if [ $ELAPSED -ge $DURATION ]; then
+        break
+    fi
+    
+    # Check if spike is still running
+    if ! kill -0 $SPIKE_PID 2>/dev/null; then
+        echo "  ERROR: Spike died at ${ELAPSED}s!"
+        tail -50 "$LOG_FILE"
+        exit 1
+    fi
+    
+    # Report every minute
+    if [ $CURRENT_TIME -ge $NEXT_REPORT ]; then
+        REMAINING=$((DURATION - ELAPSED))
+        echo "  Still running... ${ELAPSED}s elapsed, ${REMAINING}s remaining"
+        NEXT_REPORT=$((NEXT_REPORT + 60))
+        
+        # Send a keepalive message
+        tmux send-keys -t "$SESSION" "echo 'keepalive_${ELAPSED}s'" Enter
+    fi
+    
+    sleep 5
+done
+
+echo "  ✓ Completed 5-minute test"
+echo ""
+
+echo "=== Test Complete ==="
+echo "Stopping spike..."
+kill $SPIKE_PID 2>/dev/null || true
+wait $SPIKE_PID 2>/dev/null || true
+
+echo ""
+echo "=== Results ==="
+echo "Log file: $LOG_FILE"
+echo ""
+echo "Statistics from log:"
+grep "\[spike-cc\].*Stats" "$LOG_FILE" | tail -5
+echo ""
+
+OUTPUT_EVENTS=$(grep -c "handleOutputEvent\|%output" "$LOG_FILE" || echo "0")
+echo "Total output events (approx): $OUTPUT_EVENTS"
+echo ""
+
+if [ $OUTPUT_EVENTS -gt 10 ]; then
+    echo "✅ VERDICT: Control mode appears to work reliably"
+    echo "   - Survived alternate-screen transition"
+    echo "   - Parallel attach did not interfere"
+    echo "   - Ran for full 5-minute duration"
+else
+    echo "⚠️  VERDICT: Insufficient output events captured"
+    echo "   This may indicate a problem with the spike implementation"
+fi
+
+echo ""
+echo "Full log saved to: $LOG_FILE"
+echo "To review: cat $LOG_FILE"