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Chimera

Plan/Act Loop

chimera.core.loops.plan_act implements a two-phase loop inspired by Cline’s Plan/Act mode. The agent first explores the codebase with read-only tools and produces a step-by-step plan, then executes the plan with full tool access in a separate context.

Unlike PlanAndExecute which runs in a single context, PlanActLoop creates separate contexts for each phase, preventing accidental mutations during exploration.

Key Classes

Section titled “Key Classes”
ClassDescription
PlanActLoopTwo-phase loop: read-only planning, then full execution
READ_ONLY_TOOLSSet of tool names safe for planning: read_file, search, list_files, repo_map, think, read_image

Quick Start

Section titled “Quick Start”
from chimera.core.loops.plan_act import PlanActLoop


loop = PlanActLoop(plan_steps=10, act_steps=25)
result = loop.run(provider, tools, context, env)


# The plan generated in phase 1 is available after run()
print(loop.plan_output)

How It Works

Section titled “How It Works”

  1. Plan phase: The agent receives the user’s task with a “PLANNING PHASE” instruction. Only read-only tools are available. The agent explores the codebase and outputs a plan.

  2. Act phase: A new context is built with the original task plus the plan output. The agent receives full tool access and executes the plan.

  3. The combined AgentResult sums steps and cost from both phases.

Custom Read-Only Tools

Section titled “Custom Read-Only Tools”

Override the default read-only tool set:

loop = PlanActLoop(
    read_only_tools={"read_file", "search", "list_files", "think", "repo_map", "import_graph"},
    plan_steps=15,
    act_steps=30,
)

Import Reference

Section titled “Import Reference”
from chimera.core.loops.plan_act import PlanActLoop, READ_ONLY_TOOLS
Section titled “Related”