rasbt
mini-coding-agent
Python

Minimal and readable coding agent harness implementation in Python to explain the core components of coding agents.

Last updated Jul 8, 2026
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README

 

Mini-Coding-Agent

This folder contains a small standalone coding agent:

  • code: minicodingagent.py
  • CLI: mini-coding-agent
It is a minimal local agent loop with:
  • workspace snapshot collection
  • stable prompt plus turn state
  • structured tools
  • approval handling for risky tools
  • transcript and memory persistence
  • bounded delegation
The model backend is currently based on Ollama.


The detailed tutorial: Components of a Coding Agent

 

Six Core Components

Six core components of a coding agent

This coding harness is organized around six practical building blocks:

  • Live repo context
The agent collects stable workspace facts upfront, such as repo layout, instructions, and git state.
  • Prompt shape and cache reuse
A stable prompt prefix, which is separate from the changing request, transcript, and memory so repeated model calls can reuse the static parts efficiently.
  • Structured tools, validation, and permissions
The model works through named tools with checked inputs, workspace path validation, and approval gates instead of free-form arbitrary actions.
  • Context reduction and output management
Long outputs are clipped, repeated reads are deduplicated, and older transcript entries are compressed to keep prompt size under control.
  • Transcripts, memory, and resumption
The runtime keeps both a full durable transcript and a smaller working memory so sessions can be resumed while preserving important state via working memory.
  • Delegation and bounded subagents
Scoped subtasks can be delegated to helper agents that inherit enough context to help (but operate within limits).

 

Requirements

You need:

  • Python 3.10+
  • Ollama installed
  • an Ollama model pulled locally
Optional:
  • uv for environment management and the mini-coding-agent CLI entry point
This project has no Python runtime dependency beyond the standard library, so you can run it directly with python minicodingagent.py if you do not want to use uv.

 

Install Ollama

Install Ollama on your machine so the ollama command is available in your shell.

Official installation link: ollama.com/download

Then verify:

ollama --help

Start the server:

ollama serve

In another terminal, pull a model. Example:

ollama pull qwen3.5:4b

Qwen 3.5 model library:

The default in this project is qwen3.5:4b. If you have sufficient memory, it is worth trying a larger model such as qwen3.5:9b or another larger Qwen 3.5 variant. The agent just sends prompts to Ollama's /api/generate endpoint.

 

Project Setup

Clone the repo or your fork and change into it:

git clone https://github.com/rasbt/mini-coding-agent.git
cd mini-coding-agent

If you forked it first, use your fork URL instead:

git clone https://github.com/<your-github-user>/mini-coding-agent.git
cd mini-coding-agent

 

Basic Usage

Start the agent:

cd mini-coding-agent
uv run mini-coding-agent

Without uv, run the script directly:

cd mini-coding-agent
python minicodingagent.py

By default it uses:

  • model: qwen3.5:4b
  • approval: ask
For a concrete usage example, see EXAMPLE.md.

 

Approval Modes

Risky tools such as shell commands and file writes are gated by approval.

  • --approval ask
prompts before risky actions (default and recommended)
  • --approval auto
allows risky actions automatically, including arbitrary command execution and file writes by the model; use only with trusted prompts and trusted repositories
  • --approval never
denies risky actions

Example:

uv run mini-coding-agent --approval auto

 

Resume Sessions

The agent saves sessions under the target workspace root in:

.mini-coding-agent/sessions/

Resume the latest session:

uv run mini-coding-agent --resume latest

Resume a specific session:

uv run mini-coding-agent --resume 20260401-144025-2dd0aa

 

Interactive Commands

Inside the REPL, slash commands are handled directly by the agent instead of being sent to the model as a normal task.

  • /help
shows the list of available interactive commands
  • /memory
prints the distilled session memory, including the current task, tracked files, and notes
  • /session
prints the path to the current saved session JSON file
  • /reset
clears the current session history and distilled memory but keeps you in the REPL
  • /exit
exits the interactive session
  • /quit
exits the interactive session; alias for /exit

 

Main CLI Flags

uv run mini-coding-agent --help

Without uv:

python minicodingagent.py --help

CLI flags are passed before the agent starts. Use them to choose the workspace, model connection, resume behavior, approval mode, and generation limits.

Important flags:

  • --cwd
sets the workspace directory the agent should inspect and modify; default: .
  • --model
selects the Ollama model name, such as qwen3.5:4b; default: qwen3.5:4b
  • --host
points the agent at the Ollama server URL (usually not needed); default: http://127.0.0.1:11434
  • --ollama-timeout
controls how long the client waits for an Ollama response (usually not needed); default: 300 seconds
  • --resume
resumes a saved session by id or uses latest; default: start a new session
  • --approval
controls how risky tools are handled: ask, auto, or never; default: ask
  • --max-steps
limits how many model and tool turns are allowed for one user request; default: 6
  • --max-new-tokens
caps the model output length for each step; default: 512
  • --temperature
controls sampling randomness; default: 0.2
  • --top-p
controls nucleus sampling for generation; default: 0.9

 

Example

See EXAMPLE.md

 

Notes & Tips

  • The agent expects the model to emit either <tool>...</tool> or <final>...</final>.
  • Different Ollama models will follow those instructions with different reliability.
  • If the model does not follow the format well, use a stronger instruction-following model.
  • The agent is intentionally small and optimized for readability, not robustness.

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