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Pick your tier

Where do I start: Basic, Mid, Full, or Advanced?

Start as low as possible. Tiers are additive — moving up never requires changing the code you already wrote.

Decision tree

Single agent, one call, maybe with one tool?
    → Basic.

Need conversation memory, observability, guardrails, or simple
chain / parallel composition?
    → Mid.

Declared multi-step workflow with typed hand-offs, routing,
crash-resume, or per-step verifiers?
    → Full.

Writing framework code — new provider, new engine,
cross-process Plan serialisation?
    → Advanced.

Quick reference

You need Start at Key surface (import path)
One agent, one tool, one call Basic Agent, LLMEngine, Envelope, Tool, NativeTool — all from lazybridge
Memory, Store, Session, Guards, chain / parallel / as_tool, MCP, Evals, HumanEngine, verify= Mid Memory, Store, Session, Agent.chain, Agent.parallel, verify= from lazybridge; MCP from lazytools.connectors.mcp; HumanEngine from lazybridge.ext.hil
Plan + Step + sentinels, routing, parallel bands, checkpoint / resume, exporters, GraphSchema, SupervisorEngine Full Plan, Step, from_prev / from_step / from_start / from_agent, Step(routes=…), Step(parallel=True), GraphSchema, ConsoleExporter / JsonFileExporter / StructuredLogExporter from lazybridge; SupervisorEngine from lazybridge.ext.hil
Custom engine, custom provider, Plan persistence, OTel deep, Visualizer Advanced BaseProvider from lazybridge.core.providers.base; Engine Protocol from lazybridge.engines.base; Plan.to_dict / Plan.from_dict on the Plan class; OTelExporter from lazybridge.ext.otel; Visualizer from lazybridge.ext.viz

Notes

  • Tiers are additive. Adding a Memory to a Basic agent doesn't require restructuring; you just pass it as a kwarg. Same for Session, output=, verify=, tools=[...].
  • Don't reach up too early. A Plan is overkill for a 3-step text pipeline (use Agent.chain); verify= is overkill for a policy a regex Guard already enforces; a custom engine is overkill if LLMEngine(system="...", max_turns=N) covers what you need.
  • Advanced is framework authorship, not application development. If you're tweaking prompts / swapping models / building pipelines, you're in Basic / Mid / Full.

See also

  • Mental model — Engine + Tools + State, the decomposition every tier shares.
  • Progressive complexity — the twelve-rung ladder from one-liner to checkpointed pipeline.
  • Canonical vs sugar — the full table of factory shortcuts mapped back to canonical forms.