Xtuner Trace

XTuner Trace

Use this skill for the current trace layer in this repository: OpenTelemetry runtime setup, the basic public API, local setup scripts, and the trace viewer.

Current Boundary

Keep this package infrastructure-only:

• Runtime/configuration: xtuner/v1/rl/trace/runtime.py
• OTel SDK adapter: xtuner/v1/rl/trace/otel_utils.py
• Public facade: xtuner/v1/rl/trace/__init__.py
• Basic API: xtuner/v1/rl/trace/api.py
• Rollout starter preset: xtuner/v1/rl/trace/rollout_api.py
• Local trace tooling and viewer: recipe/trace/

Do not add rollout, agent, judger, Ray remote, HTTP proxy, reward, status, or session-server business semantics to api.py, runtime.py, or otel_utils.py. Keep rollout-specific starter behavior inside rollout_api.py and gated by TraceConfig.enable_rollout_trace.

Viewer Choice

Choose the viewer by the observation question:

• Use recipe/trace/viewer when the user wants rollout-oriented inspection, such as comparing samples within a training step by stage duration, status, reward/filter metadata, or recorded sample call chain.
• Use Jaeger when the question is not sample/step-centric, such as inspecting raw spans, service boundaries, cross-process causality, backend/client calls, collector/export behavior, or custom instrumentation that does not emit the rollout/sample attributes expected by the recipe viewer.

The recipe viewer reads traces.jsonl and adds XTuner rollout/sample aggregation. Jaeger remains the raw trace drill-down surface for the same traced run.

Black-Box Agent Trace Routing

When the trace request involves an agent, first ask whether this is a black-box agent trace. In this mode, XTuner exposes an OpenAI-compatible inference endpoint to the agent through SessionServer; the agent runs its native loop and calls that endpoint for LLM generation. Tool execution, environment interaction, and observation handling happen inside the agent runtime and are not directly instrumented by XTuner.

If the answer is yes, or the request mentions trajectory reconstruction, SessionServer request gaps, record_synthetic_span(...), reconstructed_agent_run, reconstructed_tool_call.N, XTuner viewer plus Jaeger display of recovered tool calls, read references/blackbox-agent-trace.md before planning or editing.

Basic API

These are the interfaces defined in xtuner/v1/rl/trace/api.py and re-exported from xtuner.v1.rl.trace:

• trace_span(name, attributes=None, parent_carrier=None)
• trace_function(name=None, attributes=None)
• trace_event(name, attributes=None)
• set_trace_attributes(attributes)
• inject_trace_context(carrier=None)

Runtime API

Use these xtuner/v1/rl/trace/runtime.py interfaces for explicit trace runtime setup:

• TraceConfig
• configure_trace(...)
• close_trace()

Rollout Starter Preset

TraceConfig(enable_rollout_trace=True) enables the built-in rollout starter trace. Its helpers live in xtuner/v1/rl/trace/rollout_api.py:

• trace_rollout_endpoint(...)
• trace_rollout_remote(...)

Keep this layer narrow: it may depend on RolloutState and Ray call boundaries, but it must not leak those dependencies into the basic API.

Rollout endpoint xtuner.span_name_path is a sample call chain, not just the current process context stack. trace_rollout_endpoint(...) should append the endpoint span name to an internal trace-only chain carried in RolloutState.extra_fields, pass that state through remote rollout boundaries, and clean the internal field at the outermost endpoint. For example, after a sample generates and then judges, judger.run should record a path like single_turn_agent_loop.run -> rollout.controller.generate -> rollout.worker.generate -> judger.run even though the local active context at judge time may only be single_turn_agent_loop.run -> judger.run. Keep this behavior in rollout_api.py and viewer tests; do not add rollout call-chain semantics to the basic trace API.

Add Trace Workflow

When adding trace instrumentation to an XTuner run:

1. Ask for or locate the launch script and training config before editing.
2. In the launch script, source recipe/trace/setup_trace.sh when XTUNER_TRACE_ENABLED=1.
3. In the training config, add TraceConfig and set enabled=True; set xtuner_viewer_enabled=True when the user needs interactive sample/step inspection. Set enable_rollout_trace=True only when the user wants the built-in rollout starter trace.
4. Before adding any trace_span(...) instrumentation, you must ask the user which stages they want to observe and which metrics each stage should expose. Do not infer default stages unless the user explicitly asks you to choose.
5. Add trace_span(...) only around the user-confirmed observed stages. Put fields known at span start in initial attributes, and update runtime or final fields with set_trace_attributes(...).
6. For cross-process or request boundaries, inject a carrier with inject_trace_context(...) and pass it to downstream trace_span(..., parent_carrier=carrier).
7. Keep transport-specific propagation at the caller boundary; do not move rollout, agent, judger, Ray, or HTTP semantics into the basic trace package.
8. Ensure the main training log includes the trace output path, XTuner viewer URL, and equivalent manual viewer command when the XTuner viewer is enabled.

Guardrails

• Do not recreate trace_utils.py, context_propagation.py, span-name registries, or business attribute builders under xtuner/v1/rl/trace.
• Do not import RolloutState, agent item classes, judgers, rollout workers, Ray actors, aiohttp clients, or trainer configs from the basic trace package.
• Do not call OpenTelemetry SDK directly from business code; use the basic API only when trace instrumentation is explicitly requested.
• Do not record prompts, responses, full configs, secrets, raw headers, stack traces, or large payloads as attributes.
• Viewer stage grouping must come from span attributes such as xtuner.stage, stage, or stage.name; otherwise fall back to the raw span name.

For concrete patterns, read references/trace-patterns.md before editing trace code.

Verification

Use focused checks:

• PYTHONPATH=. python -m compileall -q xtuner/v1/rl/trace recipe/trace
• PYTHONPATH=. python -m unittest discover -s tests/rl -p 'test_trace*.py' -v when the trace tests exist in the worktree.
• git diff --check