feat(hooks): consolidate shared transport helpers

hooks/opencode/plugin.ts

@@ -1,21 +1,50 @@
 import { Plugin } from "@opencode-ai/plugin";
+import { hostname } from "node:os";
 
 const INGEST_URL = process.env.AGENTMON_INGEST_URL || "http://localhost:8080";
+const FETCH_TIMEOUT_MS = 500;
 
 let buffer: any[] = [];
-let flushTimer: NodeJS.Timeout | null = null;
+let flushTimer: ReturnType<typeof setTimeout> | null = null;
+let isFlushing = false;
 const BATCH_SIZE = 10;
 const FLUSH_MS = 2000;
 
 let currentSessionId: string | undefined;
 let currentRunId: string | undefined;
 
+const activeSpans = new Map<string, string>();
+
+function scheduleFlush() {
+  if (!flushTimer) {
+    flushTimer = setTimeout(() => {
+      void flush();
+    }, FLUSH_MS);
+  }
+}
+
 function enqueue(event: any) {
   buffer.push(event);
   if (buffer.length >= BATCH_SIZE) {
-    flush();
-  } else if (!flushTimer) {
-    flushTimer = setTimeout(flush, FLUSH_MS);
+    void flush();
+  } else {
+    scheduleFlush();
+  }
+}
+
+async function postBatch(batch: any[]) {
+  const controller = new AbortController();
+  const timeout = setTimeout(() => controller.abort(), FETCH_TIMEOUT_MS);
+
+  try {
+    await fetch(`${INGEST_URL}/v1/events`, {
+      method: "POST",
+      headers: { "Content-Type": "application/json" },
+      body: JSON.stringify(batch),
+      signal: controller.signal,
+    });
+  } finally {
+    clearTimeout(timeout);
   }
 }
 
@@ -24,17 +53,24 @@ async function flush() {
     clearTimeout(flushTimer);
     flushTimer = null;
   }
-  if (buffer.length === 0) return;
-  
+  if (isFlushing || buffer.length === 0) return;
+
+  isFlushing = true;
   const batch = buffer.splice(0, BATCH_SIZE);
+
   try {
-    await fetch(`${INGEST_URL}/v1/events`, {
-      method: "POST",
-      headers: { "Content-Type": "application/json" },
-      body: JSON.stringify(batch),
-    });
-  } catch (e) {
+    await postBatch(batch);
+  } catch {
     console.debug("[agentmon] failed to flush events");
+  } finally {
+    isFlushing = false;
+    if (buffer.length > 0) {
+      if (buffer.length >= BATCH_SIZE) {
+        void flush();
+      } else {
+        scheduleFlush();
+      }
+    }
   }
 }
 
@@ -48,7 +84,7 @@ function buildEnvelope(type: string, data: any) {
       source: {
         framework: "opencode",
         client_id: "opencode",
-        host: require("os").hostname(),
+        host: hostname(),
       },
     },
     ...(data.correlation && { correlation: data.correlation }),
@@ -63,29 +99,32 @@ export const agentmon: Plugin = async (input) => {
       if (!currentSessionId) {
         currentSessionId = crypto.randomUUID();
         currentRunId = crypto.randomUUID();
-        
+
         enqueue(buildEnvelope("session.start", {
           correlation: { session_id: currentSessionId },
         }));
-        
+
         enqueue(buildEnvelope("run.start", {
           correlation: { session_id: currentSessionId, run_id: currentRunId },
         }));
       }
-      
+
       const spanId = crypto.randomUUID();
+      activeSpans.set(data.tool, spanId);
       enqueue(buildEnvelope("span.start", {
         correlation: { session_id: currentSessionId, run_id: currentRunId, span_id: spanId },
         attributes: { span_kind: "tool", name: data.tool },
         payload: { input: (JSON.stringify(data.input) ?? "").substring(0, 200) },
       }));
     },
-    
+
     "tool.execute.after": async (data: any) => {
       if (!currentSessionId || !currentRunId) return;
-      
+
+      const spanId = activeSpans.get(data.tool);
+      activeSpans.delete(data.tool);
       enqueue(buildEnvelope("span.end", {
-        correlation: { session_id: currentSessionId, run_id: currentRunId },
+        correlation: { session_id: currentSessionId, run_id: currentRunId, ...(spanId && { span_id: spanId }) },
         attributes: { span_kind: "tool", name: data.tool },
         payload: {
           status: data.error ? "error" : "success",
@@ -94,22 +133,22 @@ export const agentmon: Plugin = async (input) => {
         },
       }));
     },
-    
+
     "chat.message": async (data: any) => {
       if (!currentSessionId) {
         currentSessionId = data.sessionID || crypto.randomUUID();
         currentRunId = crypto.randomUUID();
-        
+
         enqueue(buildEnvelope("session.start", {
           correlation: { session_id: currentSessionId },
         }));
-        
+
         enqueue(buildEnvelope("run.start", {
           correlation: { session_id: currentSessionId, run_id: currentRunId },
         }));
       }
     },
-    
+
     "experimental.session.compacting": async (data: any) => {
       if (currentSessionId && currentRunId) {
         enqueue(buildEnvelope("span.start", {