Agent Lightning Repo Skill

Use this skill when a user asks for help with Agent Lightning (agentlightning): writing trainable agents, collecting spans and rewards, coordinating runners/stores/trainers/algorithms, using agl services, selecting example recipes, or diagnosing package/backend issues.

Agent Lightning's core loop is: a runner executes a LitAgent, a tracer emits spans into a LightningStore, algorithms read those traces and update resources, and Trainer wires those components together.

First steps for any task

1. Identify the user's workflow and route to the nearest sub-skill below.
2. If the user is using a different checkout or package version, read repo provenance before relying on version-sensitive details.
3. For install or import trouble, run or adapt scripts/check_agentlightning_install.py and read compatibility plus cross-cutting troubleshooting.
4. Treat GPU, MongoDB, cloud API, W&B/Tinker, Docker/SWE-bench, and dashboard workflows as optional unless the user explicitly provides those resources.

Route map

User intent	Use this sub-skill	What it contains
Write or wrap an agent, fix @rollout signatures, use PromptTemplate or LLM, debug one rollout	agent-authoring	Agent function/class patterns, resource injection, return contracts, runner single-step smoke
Emit rewards/messages/objects, inspect spans, adapt traces to messages/triplets, debug missing token IDs	tracing-and-instrumentation	OtelTracer, AgentOpsTracer, emitters, operation, adapters, trace troubleshooting
Operate LightningStore, runners, algorithms, Trainer.fit, Trainer.dev, status/retry behavior	runner-store-training	Store API, rollout/attempt lifecycle, resources, custom algorithms, training loop recipes
Use agl CLI, store/prometheus services, LLM proxy, vLLM bridge, endpoint checks, metrics	cli-and-services	Help-confirmed CLI flags, service launch patterns, safe LiteLLM/OpenAI-compatible checks
Choose or adapt examples such as APO, SQL, RAG, ChartQA, Unsloth, Azure, Claude Code, Tinker	examples-and-recipes	Example/backend catalog, optional dependency matrix, maintainer example rules

Installation orientation

General use:

python -m pip install --upgrade agentlightning
python - <<'PY'
import agentlightning as agl
print(agl.__version__)
print(type(agl.InMemoryLightningStore()).__name__)
PY

For source development, use the repository's uv workflow and choose only the optional groups needed for the task. CPU-only work can inspect and run base package APIs without CUDA. APO requires the apo extra (poml) plus an OpenAI-compatible endpoint for full examples. VERL/vLLM/Unsloth/vision/RAG examples require larger dependency groups and usually CUDA-compatible hardware.

Core public objects to recognize

• Agent authoring: rollout, llm_rollout, prompt_rollout, LitAgent, PromptTemplate, LLM, ProxyLLM, NamedResources.
• Execution: LitAgentRunner, Runner, Hook, Trainer, Algorithm, FastAlgorithm, Baseline, algo.
• Store/control plane: LightningStore, InMemoryLightningStore, LightningStoreClient, LightningStoreServer, LightningStoreThreaded, RolloutConfig.
• Tracing: OtelTracer, AgentOpsTracer, DummyTracer, emit_reward, emit_message, emit_object, emit_exception, operation, find_final_reward, TracerTraceToTriplet, LlmProxyTraceToTriplet, TraceToMessages.
• Services: agl, LLMProxy, ProxyLLM, metrics backends, OpenAI-compatible endpoint patterns.

Fast validation

Use this when a user asks whether the installed package is basically usable:

python scripts/check_agentlightning_install.py

For deeper workflow checks, run the nearest sub-skill smoke script:

• Agent authoring: python sub-skills/agent-authoring/scripts/agent_rollout_smoke.py
• Tracing: python sub-skills/tracing-and-instrumentation/scripts/local_trace_smoke.py
• Store/training control plane: python sub-skills/runner-store-training/scripts/store_status_smoke.py
• Services: python sub-skills/cli-and-services/scripts/check_litellm_proxy.py --help or python sub-skills/cli-and-services/scripts/check_prometheus_metrics.py --duration 1 --host 127.0.0.1

Run scripts from the generated skill directory or pass explicit paths/URLs where the script supports them. The scripts are safe by default: they do not train models, download data, mutate Docker/Mongo/Ray, or print secrets.

Known limits

This skill was verified for CPU-compatible package import, CLI help, and in-memory store/runner/tracing smokes. It preserves guidance for optional GPU/cloud/service workflows but does not claim those backends were available or verified. When a user requests optional workflows, first confirm or detect the required hardware, credentials, endpoints, datasets, and dependency groups before running expensive commands.