feat(logging): add usage logging hooks for AI stack monitoring

- Add usage-logging hook that sends events to log-ingest service
- Track session start/end, tool calls, and token usage
- Integrate with LOG_INGEST_URL environment variable
- Update hooks index to include usage-logging

src/config/schema.ts

@@ -83,6 +83,7 @@ export const HookNameSchema = z.enum([
   "start-work",
   "sisyphus-orchestrator",
   "todo-codebase-compaction",
+  "usage-logging",
 ])
 
 export const BuiltinCommandNameSchema = z.enum([

src/hooks/index.ts

@@ -30,3 +30,4 @@ export { createTaskResumeInfoHook } from "./task-resume-info";
 export { createStartWorkHook } from "./start-work";
 export { createSisyphusOrchestratorHook } from "./sisyphus-orchestrator";
 export { createTodoCodebaseCompactionInjector, createCustomCompactionHook } from "./todo-codebase-compaction";
+export { createUsageLoggingHook } from "./usage-logging";

src/hooks/usage-logging/index.ts

@@ -0,0 +1,229 @@
+import { createHash } from 'crypto';
+
+interface LogEvent {
+  timestamp: string;
+  stack_name: string;
+  session_id: string;
+  event_type: string;
+  data: Record<string, unknown>;
+}
+
+interface UsageLoggingOptions {
+  ingestUrl?: string;
+  stackName?: string;
+  batchSize?: number;
+  flushIntervalMs?: number;
+}
+
+const DEFAULT_INGEST_URL = process.env.LOG_INGEST_URL || 'http://10.100.0.20:3102/ingest';
+const DEFAULT_STACK_NAME = process.env.STACK_NAME || 'unknown';
+
+function hashContent(content: string): string {
+  return createHash('sha256').update(content).digest('hex').substring(0, 16);
+}
+
+function getWordCount(content: string): number {
+  return content.split(/\s+/).filter(Boolean).length;
+}
+
+export function createUsageLoggingHook(options: UsageLoggingOptions = {}) {
+  const {
+    ingestUrl = DEFAULT_INGEST_URL,
+    stackName = DEFAULT_STACK_NAME,
+    batchSize = 10,
+    flushIntervalMs = 5000,
+  } = options;
+
+  const enabled = process.env.USAGE_LOGGING_ENABLED !== 'false';
+  if (!enabled) {
+    return { event: async () => {} };
+  }
+
+  const eventBuffer: LogEvent[] = [];
+  let flushTimer: ReturnType<typeof setTimeout> | null = null;
+  const sessionStats = new Map<string, {
+    startTime: number;
+    messageCount: number;
+    toolUseCount: number;
+    tokensIn: number;
+    tokensOut: number;
+  }>();
+
+  async function flushEvents(): Promise<void> {
+    if (eventBuffer.length === 0) return;
+
+    const eventsToSend = [...eventBuffer];
+    eventBuffer.length = 0;
+
+    try {
+      const response = await fetch(`${ingestUrl}/batch`, {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify(eventsToSend),
+        signal: AbortSignal.timeout(5000)
+      });
+
+      if (!response.ok) {
+        console.error(`[UsageLogging] Failed to send events: ${response.status}`);
+      }
+    } catch (error) {
+      console.error('[UsageLogging] Error sending events:', error);
+    }
+  }
+
+  function queueEvent(sessionId: string, eventType: string, data: Record<string, unknown>): void {
+    eventBuffer.push({
+      timestamp: new Date().toISOString(),
+      stack_name: stackName,
+      session_id: sessionId,
+      event_type: eventType,
+      data
+    });
+
+    if (eventBuffer.length >= batchSize) {
+      flushEvents();
+    } else if (!flushTimer) {
+      flushTimer = setTimeout(() => {
+        flushTimer = null;
+        flushEvents();
+      }, flushIntervalMs);
+    }
+  }
+
+  function getOrCreateSessionStats(sessionId: string) {
+    if (!sessionStats.has(sessionId)) {
+      sessionStats.set(sessionId, {
+        startTime: Date.now(),
+        messageCount: 0,
+        toolUseCount: 0,
+        tokensIn: 0,
+        tokensOut: 0
+      });
+    }
+    return sessionStats.get(sessionId)!;
+  }
+
+  return {
+    event: async (input: { event: { type: string; properties?: Record<string, unknown> } }) => {
+      const { event } = input;
+      const props = event.properties || {};
+
+      try {
+        switch (event.type) {
+          case 'session.created': {
+            const info = props.info as { id?: string } | undefined;
+            if (info?.id) {
+              getOrCreateSessionStats(info.id);
+              queueEvent(info.id, 'session_start', {
+                start_time: Date.now()
+              });
+            }
+            break;
+          }
+
+          case 'session.deleted': {
+            const info = props.info as { id?: string } | undefined;
+            if (info?.id) {
+              const stats = sessionStats.get(info.id);
+              if (stats) {
+                queueEvent(info.id, 'session_end', {
+                  duration_ms: Date.now() - stats.startTime,
+                  total_messages: stats.messageCount,
+                  total_tool_uses: stats.toolUseCount,
+                  total_tokens_in: stats.tokensIn,
+                  total_tokens_out: stats.tokensOut
+                });
+                sessionStats.delete(info.id);
+              }
+            }
+            break;
+          }
+
+          case 'message.created': {
+            const sessionID = props.sessionID as string | undefined;
+            const message = props.message as { role?: string; content?: string } | undefined;
+            if (sessionID && message) {
+              const stats = getOrCreateSessionStats(sessionID);
+              stats.messageCount++;
+              
+              const content = typeof message.content === 'string' 
+                ? message.content 
+                : JSON.stringify(message.content || '');
+              
+              queueEvent(sessionID, 'message', {
+                role: message.role || 'unknown',
+                content_hash: hashContent(content),
+                content_length: content.length,
+                word_count: getWordCount(content),
+                message_number: stats.messageCount
+              });
+            }
+            break;
+          }
+
+          case 'tool.started': {
+            const sessionID = props.sessionID as string | undefined;
+            const tool = props.tool as { name?: string } | undefined;
+            if (sessionID && tool?.name) {
+              queueEvent(sessionID, 'tool_start', {
+                tool: tool.name,
+                start_time: Date.now()
+              });
+            }
+            break;
+          }
+
+          case 'tool.completed': {
+            const sessionID = props.sessionID as string | undefined;
+            const tool = props.tool as { name?: string } | undefined;
+            const result = props.result as { error?: unknown } | undefined;
+            if (sessionID && tool?.name) {
+              const stats = getOrCreateSessionStats(sessionID);
+              stats.toolUseCount++;
+              
+              queueEvent(sessionID, 'tool_use', {
+                tool: tool.name,
+                success: !result?.error,
+                error_message: result?.error ? String(result.error) : undefined,
+                tool_use_number: stats.toolUseCount
+              });
+            }
+            break;
+          }
+
+          case 'session.error': {
+            const sessionID = props.sessionID as string | undefined;
+            const error = props.error as { message?: string; code?: string } | undefined;
+            if (sessionID) {
+              queueEvent(sessionID, 'error', {
+                error_message: error?.message || 'Unknown error',
+                error_code: error?.code
+              });
+            }
+            break;
+          }
+
+          case 'tokens.used': {
+            const sessionID = props.sessionID as string | undefined;
+            const usage = props.usage as { input_tokens?: number; output_tokens?: number } | undefined;
+            if (sessionID && usage) {
+              const stats = getOrCreateSessionStats(sessionID);
+              stats.tokensIn += usage.input_tokens || 0;
+              stats.tokensOut += usage.output_tokens || 0;
+              
+              queueEvent(sessionID, 'tokens', {
+                tokens_in: usage.input_tokens,
+                tokens_out: usage.output_tokens,
+                total_tokens_in: stats.tokensIn,
+                total_tokens_out: stats.tokensOut
+              });
+            }
+            break;
+          }
+        }
+      } catch (error) {
+        console.error('[UsageLogging] Error processing event:', error);
+      }
+    }
+  };
+}

src/index.ts

@@ -31,6 +31,7 @@ import {
   createStartWorkHook,
   createSisyphusOrchestratorHook,
   createPrometheusMdOnlyHook,
+  createUsageLoggingHook,
 } from "./hooks";
 import {
   contextCollector,
@@ -212,6 +213,13 @@ const OhMyOpenCodePlugin: Plugin = async (ctx) => {
     ? createPrometheusMdOnlyHook(ctx)
     : null;
 
+  const usageLogging = isHookEnabled("usage-logging")
+    ? createUsageLoggingHook({
+        stackName: process.env.STACK_NAME,
+        ingestUrl: process.env.LOG_INGEST_URL,
+      })
+    : null;
+
   const taskResumeInfo = createTaskResumeInfoHook();
 
   const backgroundManager = new BackgroundManager(ctx);
@@ -411,6 +419,7 @@ const OhMyOpenCodePlugin: Plugin = async (ctx) => {
       await interactiveBashSession?.event(input);
       await ralphLoop?.event(input);
       await sisyphusOrchestrator?.handler(input);
+      await usageLogging?.event(input);
 
       const { event } = input;
       const props = event.properties as Record<string, unknown> | undefined;