Instructions

What the agent is told. Module: regista/instructions.py.

An Instructions object is a layered system prompt: a base identity plus named sections, rendered once per session and recorded verbatim in the session.start trace event.

from regista import Agent, Instructions

instructions = Instructions(
    base="You are a code-maintenance agent.",
    sections={"Style": "Prefer small diffs. Never reformat unrelated code."},
)
print(instructions.render())
# You are a code-maintenance agent.
#
# ## Style
#
# Prefer small diffs. Never reformat unrelated code.

agent = Agent(provider=..., instructions=instructions)

A plain string works too — Agent coerces it to Instructions(base=...):

agent = Agent(provider=..., instructions="You are a greeter.")

with_section(title, body) returns a new frozen copy, which is how Skills (v0.3) will contribute instruction fragments without mutating anything.

Why it matters for replay

The rendered string is part of every ModelRequest, so it is part of every request_hash. Change one word of the prompt and a strict replay fails with a diff pointing at request.system — prompt drift is a first-class, detectable change.