feat: add @eggjs/agent-tracing package for AI agent tracing (#412)

## Summary

- Add new `@eggjs/agent-tracing` package for AI agent LLM call tracing
- Support tracing LangGraph-based and Claude Agent SDK-based AI agent
invocations with structured span/trace data
- `LangGraphTracer`: extends LangChain `BaseTracer`, hooks into graph
lifecycle events
- `ClaudeAgentTracer`: converts Claude SDK messages to LangChain Run
format, supports both batch and streaming modes
- `TracingService`: shared log formatting, OSS upload, and log service
sync
- `AbstractOssClient`/`AbstractLogServiceClient`: IoC injection
interfaces for pluggable backends

Adapted from eggjs/egg#5822 for tegg monorepo
conventions (CJS module system, mocha tests, lerna versioning).

## Test plan

- [x] All 52 mocha tests passing (`npm test
--workspace=core/agent-tracing`)
- [x] TypeScript type checking passes (`tsc --noEmit`)
- [x] Package structure follows existing `core/*` conventions

🤖 Generated with [Claude Code](https://claude.com/claude-code)

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **New Features**
* Added comprehensive tracing for Claude agents and LangGraph workflows
with configurable agent naming.
* Optional OSS uploads and log-service syncing for large trace fields
and centralized trace management.
* Published a new package with root and subpath exports for tracer
consumers.

* **Tests**
* Added extensive unit and integration tests covering tracer behavior,
sessions, env handling, and error cases.

* **Chores**
* Added TypeScript build configs and package manifest for the new
tracing package.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: jerryliang64

core/agent-tracing/claude.ts

@@ -0,0 +1,2 @@
+export * from './index';
+export { ClaudeAgentTracer, TraceSession } from './src/ClaudeAgentTracer';

core/agent-tracing/index.ts

@@ -0,0 +1,3 @@
+export * from './src/types';
+export { AbstractOssClient } from './src/AbstractOssClient';
+export { AbstractLogServiceClient } from './src/AbstractLogServiceClient';

core/agent-tracing/langgraph.ts

@@ -0,0 +1,2 @@
+export * from './index';
+export { LangGraphTracer } from './src/LangGraphTracer';

core/agent-tracing/package.json

@@ -0,0 +1,91 @@
+{
+  "name": "@eggjs/agent-tracing",
+  "version": "3.72.0",
+  "description": "Tracing support for AI agents (LangGraph, Claude Agent SDK)",
+  "keywords": [
+    "agent",
+    "claude",
+    "egg",
+    "langchain",
+    "langgraph",
+    "tegg",
+    "tracing",
+    "typescript"
+  ],
+  "main": "dist/index.js",
+  "files": [
+    "dist/**/*.js",
+    "dist/**/*.d.ts"
+  ],
+  "typings": "dist/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "default": "./dist/index.js"
+    },
+    "./claude": {
+      "types": "./dist/claude.d.ts",
+      "default": "./dist/claude.js"
+    },
+    "./langgraph": {
+      "types": "./dist/langgraph.d.ts",
+      "default": "./dist/langgraph.js"
+    },
+    "./package.json": "./package.json"
+  },
+  "scripts": {
+    "test": "node --eval \"process.exit(parseInt(process.versions.node) < 18 ? 0 : 1)\" || cross-env NODE_ENV=test NODE_OPTIONS='--no-deprecation' mocha",
+    "clean": "tsc -b --clean",
+    "tsc": "ut run clean && tsc -p ./tsconfig.json",
+    "tsc:pub": "ut run clean && tsc -p ./tsconfig.pub.json",
+    "prepublishOnly": "ut tsc:pub"
+  },
+  "homepage": "https://github.com/eggjs/tegg",
+  "bugs": {
+    "url": "https://github.com/eggjs/tegg/issues"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git@github.com:eggjs/tegg.git",
+    "directory": "core/agent-tracing"
+  },
+  "engines": {
+    "node": ">=18.0.0"
+  },
+  "author": "killagu <killa123@126.com>",
+  "license": "MIT",
+  "dependencies": {
+    "@eggjs/tegg-background-task": "^3.72.0",
+    "@eggjs/core-decorator": "^3.72.0",
+    "@eggjs/tegg-types": "^3.72.0",
+    "onelogger": "^1.0.1"
+  },
+  "peerDependencies": {
+    "@anthropic-ai/claude-agent-sdk": ">=0.2.52",
+    "@langchain/core": ">=1.1.1"
+  },
+  "peerDependenciesMeta": {
+    "@anthropic-ai/claude-agent-sdk": {
+      "optional": true
+    },
+    "@langchain/core": {
+      "optional": true
+    }
+  },
+  "devDependencies": {
+    "@anthropic-ai/claude-agent-sdk": "^0.2.52",
+    "@anthropic-ai/sdk": "^0.78.0",
+    "@eggjs/tegg-common-util": "^3.72.0",
+    "@langchain/core": "^1.1.29",
+    "@langchain/langgraph": "^0.2.74",
+    "@types/mocha": "^10.0.1",
+    "@types/node": "^20.2.4",
+    "cross-env": "^7.0.3",
+    "mocha": "^10.2.0",
+    "ts-node": "^10.9.1",
+    "typescript": "^5.0.4"
+  },
+  "publishConfig": {
+    "access": "public"
+  }
+}

core/agent-tracing/src/AbstractLogServiceClient.ts

@@ -0,0 +1,31 @@
+/**
+ * Abstract log service client for dependency injection.
+ *
+ * To enable log service syncing in TracingService, implement this class in your application
+ * and register it with Tegg IoC. The implementation class MUST be named `LogServiceClient`
+ * (or use `@SingletonProto({ name: 'logServiceClient' })`) so the container can resolve it.
+ *
+ * @example
+ * ```typescript
+ * import { SingletonProto } from '@eggjs/core-decorator';
+ * import { AccessLevel } from '@eggjs/tegg-types';
+ * import { AbstractLogServiceClient } from '@eggjs/agent-tracing';
+ *
+ * // Class name must be LogServiceClient (registers as 'logServiceClient' in the IoC container)
+ * @SingletonProto({ accessLevel: AccessLevel.PUBLIC })
+ * export class LogServiceClient extends AbstractLogServiceClient {
+ *   async send(log: string): Promise<void> {
+ *     await fetch('https://log.example.com/api', {
+ *       method: 'POST',
+ *       headers: { 'content-type': 'application/json' },
+ *       body: JSON.stringify({ log }),
+ *     });
+ *   }
+ * }
+ * ```
+ *
+ * If no implementation is registered, log service syncing is silently skipped.
+ */
+export abstract class AbstractLogServiceClient {
+  abstract send(log: string): Promise<void>;
+}

core/agent-tracing/src/AbstractOssClient.ts

@@ -0,0 +1,27 @@
+/**
+ * Abstract OSS client for dependency injection.
+ *
+ * To enable OSS uploads in TracingService, implement this class in your application
+ * and register it with Tegg IoC. The implementation class MUST be named `OssClient`
+ * (or use `@SingletonProto({ name: 'ossClient' })`) so the container can resolve it.
+ *
+ * @example
+ * ```typescript
+ * import { SingletonProto } from '@eggjs/core-decorator';
+ * import { AccessLevel } from '@eggjs/tegg-types';
+ * import { AbstractOssClient } from '@eggjs/agent-tracing';
+ *
+ * // Class name must be OssClient (registers as 'ossClient' in the IoC container)
+ * @SingletonProto({ accessLevel: AccessLevel.PUBLIC })
+ * export class OssClient extends AbstractOssClient {
+ *   async put(key: string, content: string | Buffer): Promise<void> {
+ *     // your OSS implementation here
+ *   }
+ * }
+ * ```
+ *
+ * If no implementation is registered, OSS uploads are silently skipped.
+ */
+export abstract class AbstractOssClient {
+  abstract put(key: string, content: string | Buffer): Promise<void>;
+}