agent-tracing（Agent 追踪）

Agent Tracing CLI Guide

@lobechat/agent-tracing is a zero-config local dev tool that records agent execution snapshots to disk and provides a CLI to inspect them.

How It Works

In NODE_ENV=development, AgentRuntimeService.executeStep() automatically records each step to .agent-tracing/ as partial snapshots. When the operation completes, the partial is finalized into a complete ExecutionSnapshot JSON file.

Data flow: executeStep loop -> build StepPresentationData -> write partial snapshot to disk -> on completion, finalize to .agent-tracing/{timestamp}_{traceId}.json

Context engine capture: In RuntimeExecutors.ts, the call_llm executor emits a context_engine_result event after serverMessagesEngine() processes messages. This event carries the full contextEngineInput (DB messages, systemRole, model, knowledge, tools, userMemory, etc.) and the processed output messages (the final LLM payload).

Package Location

packages/agent-tracing/
  src/
    types.ts          # ExecutionSnapshot, StepSnapshot, SnapshotSummary
    store/
      types.ts        # ISnapshotStore interface
      file-store.ts   # FileSnapshotStore (.agent-tracing/*.json)
    recorder/
      index.ts        # appendStepToPartial(), finalizeSnapshot()
    viewer/
      index.ts        # Terminal rendering: renderSnapshot, renderStepDetail, renderMessageDetail, renderSummaryTable, renderPayload, renderPayloadTools, renderMemory
    cli/
      index.ts        # CLI entry point (#!/usr/bin/env bun)
      inspect.ts      # Inspect command (default)
      partial.ts      # Partial snapshot commands (list, inspect, clean)
    index.ts          # Barrel exports

Data Storage

• Completed snapshots: .agent-tracing/{ISO-timestamp}_{traceId-short}.json
• Latest symlink: .agent-tracing/latest.json
• In-progress partials: .agent-tracing/_partial/{operationId}.json
• FileSnapshotStore resolves from process.cwd() — run CLI from the repo root

CLI Commands

All commands run from the repo root:

# View latest trace (tree overview, `inspect` is the default command)
agent-tracing
agent-tracing inspect
agent-tracing inspect <traceId>
agent-tracing inspect latest

# List recent snapshots
agent-tracing list
agent-tracing list -l 20

# Inspect specific step (-s is short for --step)
agent-tracing inspect <traceId> -s 0

# View messages (-m is short for --messages)
agent-tracing inspect <traceId> -s 0 -m

# View full content of a specific message (by index shown in -m output)
agent-tracing inspect <traceId> -s 0 --msg 2
agent-tracing inspect <traceId> -s 0 --msg-input 1

# View tool call/result details (-t is short for --tools)
agent-tracing inspect <traceId> -s 1 -t

# View raw events (-e is short for --events)
agent-tracing inspect <traceId> -s 0 -e

# View runtime context (-c is short for --context)
agent-tracing inspect <traceId> -s 0 -c

# View context engine input overview (-p is short for --payload)
agent-tracing inspect <traceId> -p
agent-tracing inspect <traceId> -s 0 -p

# View available tools in payload (-T is short for --payload-tools)
agent-tracing inspect <traceId> -T
agent-tracing inspect <traceId> -s 0 -T

# View user memory (-M is short for --memory)
agent-tracing inspect <traceId> -M
agent-tracing inspect <traceId> -s 0 -M

# Raw JSON output (-j is short for --json)
agent-tracing inspect <traceId> -j
agent-tracing inspect <traceId> -s 0 -j

# List in-progress partial snapshots
agent-tracing partial list

# Inspect a partial (use `inspect` directly — all flags work with partial IDs)
agent-tracing inspect <partialOperationId>
agent-tracing inspect <partialOperationId> -T
agent-tracing inspect <partialOperationId> -p

# Clean up stale partial snapshots
agent-tracing partial clean

Inspect Flag Reference

Flags marked "Default Step: 0" auto-select step 0 if --step is not provided. All flags support latest or omitted traceId.

Typical Debug Workflow

# 1. Trigger an agent operation in the dev UI

# 2. See the overview
agent-tracing inspect

# 3. List all traces, get traceId
agent-tracing list

# 4. Quick overview of what was fed into context engine
agent-tracing inspect -p

# 5. Inspect a specific step's messages to see what was sent to the LLM
agent-tracing inspect TRACE_ID -s 0 -m

# 6. Drill into a truncated message for full content
agent-tracing inspect TRACE_ID -s 0 --msg 2

# 7. Check available tools vs actual tool calls
agent-tracing inspect -T      # available tools
agent-tracing inspect -s 1 -t # actual tool calls & results

# 8. Inspect user memory injected into the conversation
agent-tracing inspect -M

# 9. Diff system role between steps (multi-step agents)
agent-tracing inspect TRACE_ID -r -d 2

Key Types

interface ExecutionSnapshot {
  traceId: string;
  operationId: string;
  model?: string;
  provider?: string;
  startedAt: number;
  completedAt?: number;
  completionReason?:
    | 'done'
    | 'error'
    | 'interrupted'
    | 'max_steps'
    | 'cost_limit'
    | 'waiting_for_human';
  totalSteps: number;
  totalTokens: number;
  totalCost: number;
  error?: { type: string; message: string };
  steps: StepSnapshot[];
}

interface StepSnapshot {
  stepIndex: number;
  stepType: 'call_llm' | 'call_tool';
  executionTimeMs: number;
  content?: string; // LLM output
  reasoning?: string; // Reasoning/thinking
  inputTokens?: number;
  outputTokens?: number;
  toolsCalling?: Array<{ apiName: string; identifier: string; arguments?: string }>;
  toolsResult?: Array<{
    apiName: string;
    identifier: string;
    isSuccess?: boolean;
    output?: string;
  }>;
  messages?: any[]; // DB messages before step
  context?: { phase: string; payload?: unknown; stepContext?: unknown };
  events?: Array<{ type: string; [key: string]: unknown }>;
  // context_engine_result event contains:
  //   input: full contextEngineInput (messages, systemRole, model, knowledge, tools, userMemory, ...)
  //   output: processed messages array (final LLM payload)
}

--messages Output Structure

When using --messages, the output shows three sections (if context engine data is available):

1. Context Engine Input — DB messages passed to the engine, with [0], [1],... indices. Use --msg-input N to view full content.
2. Context Engine Params — systemRole, model, provider, knowledge, tools, userMemory, etc.
3. Final LLM Payload — Processed messages after context engine (system date injection, user memory, history truncation, etc.), with [0], [1],... indices. Use --msg N to view full content.

Integration Points

• Recording: src/server/services/agentRuntime/AgentRuntimeService.ts — in the executeStep() method, after building stepPresentationData, writes partial snapshot in dev mode
• Context engine event: src/server/modules/AgentRuntime/RuntimeExecutors.ts — in call_llm executor, after serverMessagesEngine() returns, emits context_engine_result event
• Store: FileSnapshotStore reads/writes to .agent-tracing/ relative to process.cwd()