regista

The agent harness with a flight recorder.

regista is an observability-first agent harness for Python: the runtime layer that turns a stateless LLM API into an agent that can act. Every session is recorded as a structured, append-only trace — complete enough to deterministically replay the entire session with zero API calls and zero cost.

Where to go

• Quickstart — an agent in five minutes, with or without an API key.
• The nine primitives — the map of the whole system; every concept page hangs off it.
• Deterministic replay — the differentiator, explained.
• API reference — generated from the docstrings.

The repository's ARCHITECTURE.md is the deep-dive companion: layer positioning, the dependency diagram, the life of a request, and the trace schema contract.

The pitch in one code block

result = await agent.run("Fix the failing test")     # traced, budgeted, gated
replayed = await replay(result.trace_path)           # re-run it: $0, no keys, no effects
assert replayed.output == result.output              # hash-verified, call by call