fix screen recording: resolve relative paths, buffer chunks, wait for encoder

extension/src/background.ts

@@ -27,6 +27,44 @@ let tabGroupQueue: Promise<void> = Promise.resolve()
 // This ensures Playwright can build the iframe frame tree when connecting over CDP.
 let autoAttachParams: Protocol.Target.SetAutoAttachRequest | null = null
 
+// Buffer for recording chunks when WebSocket isn't ready.
+// Chunks are keyed by tabId and flushed when WebSocket opens.
+interface BufferedChunk {
+  tabId: number
+  data?: number[]
+  final?: boolean
+}
+const recordingChunkBuffer: BufferedChunk[] = []
+
+/**
+ * Flush buffered recording chunks to the WebSocket.
+ * Called when WebSocket becomes ready.
+ */
+function flushRecordingChunkBuffer(ws: WebSocket): void {
+  if (recordingChunkBuffer.length === 0) {
+    return
+  }
+  
+  logger.debug(`Flushing ${recordingChunkBuffer.length} buffered recording chunks`)
+  
+  while (recordingChunkBuffer.length > 0) {
+    const chunk = recordingChunkBuffer.shift()!
+    const { tabId, data, final } = chunk
+    
+    // Send metadata message first
+    ws.send(JSON.stringify({
+      method: 'recordingData',
+      params: { tabId, final },
+    }))
+    
+    // Then send binary data if not final
+    if (data && !final) {
+      const buffer = new Uint8Array(data)
+      ws.send(buffer)
+    }
+  }
+}
+
 class ConnectionManager {
   ws: WebSocket | null = null
   private connectionPromise: Promise<void> | null = null
@@ -106,6 +144,10 @@ class ConnectionManager {
         settled = true
         logger.debug('WebSocket connected')
         clearTimeout(timeout)
+        
+        // Flush any buffered recording chunks now that WebSocket is ready
+        flushRecordingChunkBuffer(socket)
+        
         resolve()
       }
 
@@ -1486,6 +1528,11 @@ chrome.runtime.onMessage.addListener((message, _sender, _sendResponse) => {
         const buffer = new Uint8Array(data)
         connectionManager.ws.send(buffer)
       }
+    } else {
+      // Buffer chunks when WebSocket isn't ready - they'll be flushed when it opens.
+      // This prevents data loss during brief disconnections or slow WebSocket startup.
+      logger.debug(`Buffering recording chunk for tab ${tabId} (WebSocket not ready)`)
+      recordingChunkBuffer.push({ tabId, data, final })
     }
     
     return false // Sync response, no need to keep channel open

extension/src/offscreen.ts

@@ -154,8 +154,22 @@ async function handleStartRecording(params: OffscreenStartRecordingMessage): Pro
       console.log(`MediaRecorder stopped for tab ${tabId}`)
     }
 
-    // Start with 1 second chunks
-    recorder.start(1000)
+    // Wait for MediaRecorder to actually start before returning.
+    // This ensures the encoder is initialized and ready to capture frames.
+    await new Promise<void>((resolve, reject) => {
+      const timeout = setTimeout(() => {
+        reject(new Error('MediaRecorder failed to start within 5 seconds'))
+      }, 5000)
+      
+      recorder.onstart = () => {
+        clearTimeout(timeout)
+        console.log(`MediaRecorder started for tab ${tabId}`)
+        resolve()
+      }
+      
+      // Start with 1 second chunks
+      recorder.start(1000)
+    })
 
     return { success: true, tabId, startedAt, mimeType: 'video/mp4' }
   } catch (error: any) {

playwriter/src/screen-recording.ts

@@ -7,6 +7,7 @@
  */
 
 import os from 'node:os'
+import path from 'node:path'
 import type { Page } from 'playwright-core'
 import type {
   StartRecordingResult,
@@ -96,10 +97,14 @@ export async function startRecording(options: StartRecordingOptions): Promise<Re
     relayPort = 19988,
   } = options
   
+  // Resolve relative paths to absolute using the caller's cwd.
+  // The relay server may have a different cwd, so we must resolve here.
+  const absoluteOutputPath = path.resolve(outputPath)
+  
   const response = await fetch(`http://127.0.0.1:${relayPort}/recording/start`, {
     method: 'POST',
     headers: { 'Content-Type': 'application/json' },
-    body: JSON.stringify({ sessionId, frameRate, videoBitsPerSecond, audioBitsPerSecond, audio, outputPath }),
+    body: JSON.stringify({ sessionId, frameRate, videoBitsPerSecond, audioBitsPerSecond, audio, outputPath: absoluteOutputPath }),
   })
 
   const result = await response.json() as StartRecordingResult