heartbeat added

netlify/functions/agent-proxy.js

@@ -140,18 +140,35 @@ Please follow your instructions to produce the funding outlook brief.`
   }
 
   // ----- Pipe agent activity to the client -----
-  // The agent emits multiple event types. We surface:
-  //   - agent.message text blocks (narration)
-  //   - agent.tool_use for the `write` tool, whose `input.content` IS the
-  //     final brief the agent produces (it writes it as a Markdown file in
-  //     the sandbox instead of streaming it back)
-  //   - lightweight status lines for other tool calls so the UI keeps moving
+  // Long stretches between agent.message events (model "thinking",
+  // multi-tool batches, etc.) can silence the response stream long enough
+  // that Netlify's edge proxy drops the connection. To keep bytes flowing
+  // we (a) forward extra event types as concise status lines and (b) emit
+  // a periodic heartbeat space when the upstream goes quiet.
   const encoder = new TextEncoder()
   const seenEventIds = new Set()
   const writtenFiles = new Set() // dedupe writes by path
+  const HEARTBEAT_MS = 10_000
+
   const stream = new ReadableStream({
     async start(controller) {
-      const send = (s) => controller.enqueue(encoder.encode(s))
+      let lastSendAt = Date.now()
+      const send = (s) => {
+        controller.enqueue(encoder.encode(s))
+        lastSendAt = Date.now()
+      }
+      // Zero-width space — invisible in rendered Markdown but counts as a
+      // byte on the wire, which is enough to defeat proxy idle-timeouts.
+      const heartbeat = setInterval(() => {
+        if (Date.now() - lastSendAt >= HEARTBEAT_MS) {
+          try {
+            controller.enqueue(encoder.encode('\u200B'))
+            lastSendAt = Date.now()
+          } catch {
+            /* controller may have closed */
+          }
+        }
+      }, HEARTBEAT_MS / 2)
 
       try {
         for await (const event of upstream) {
@@ -170,6 +187,11 @@ Please follow your instructions to produce the funding outlook brief.`
                 break
               }
 
+              case 'agent.thinking': {
+                send(`\n\n_💭 thinking…_\n\n`)
+                break
+              }
+
               case 'agent.tool_use': {
                 // The write tool carries the actual brief in input.content.
                 if (
@@ -194,6 +216,20 @@ Please follow your instructions to produce the funding outlook brief.`
                 break
               }
 
+              case 'agent.tool_result':
+              case 'agent.mcp_tool_result': {
+                if (event.is_error) {
+                  const msg =
+                    (Array.isArray(event.content) &&
+                      event.content[0]?.text) ||
+                    'tool error'
+                  send(`\n\n_⚠️ tool error: ${String(msg).slice(0, 200)}_\n\n`)
+                } else {
+                  send(`\n\n_✓ result_\n\n`)
+                }
+                break
+              }
+
               case 'session.error': {
                 const msg = event.error?.message || 'unknown session error'
                 send(`\n\n[session error: ${msg}]`)
@@ -211,8 +247,10 @@ Please follow your instructions to produce the funding outlook brief.`
             break
           }
         }
+        clearInterval(heartbeat)
         controller.close()
       } catch (err) {
+        clearInterval(heartbeat)
         send(`\n\n[stream error: ${err.message || err}]`)
         controller.close()
       }