Thread Contract MCP Server

Thread-scoped runtime contracts for AI coding agents.

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What Is Thread Contract?

Thread Contract is a local runtime contract layer for AI coding-agent threads. It lets users pin explicit, thread-scoped rules such as "do not commit unless I ask" or "read PLAN.md before editing" without turning those rules into project policy or long-term memory.

It stores rules in local SQLite, exposes management tools through MCP, provides a small local Web UI, and can inject active rules before every Codex or Claude Code user turn through a UserPromptSubmit hook.

Use it when an instruction should survive a long coding-agent conversation, but should not become a permanent repository rule or hidden memory.

How It Differs From Rules, Memory, And Skills

Thread Contract is not another memory system or prompt template. It is a runtime contract for the current thread: explicit temporary rules that stay visible and enforceable without becoming repository policy or global memory.

Approach	Best For	Not For
AGENTS.md / CLAUDE.md	Long-term project norms and fixed development rules	Temporary task requirements; frequent edits pollute the repository
Long-term memory	User preferences and cross-conversation information	Short-term constraints inside the current task
Skill / prompt templates	Reusable capabilities and fixed workflows	Manual triggering; not suited for stable every-turn enforcement
Thread Contract	Temporary rule contracts for the current thread	Global long-term memory or project-wide policy changes

Usage Screenshots

These images show the core workflow: adding thread-scoped rules from an agent thread and editing the same list in the local Web UI.

Thread Contract rules can be added and confirmed from a coding-agent thread:

The same list can be edited in the local Web UI:

Install

Version 0.1.0 is source-install first. PyPI publishing, MCP Registry publishing, Docker images, and hosted sync are intentionally out of scope for this release.

Requirements:

• Python 3.10 or newer.
• Codex or Claude Code for host integration.
• Optional: mcp Python package only if you want the alternate SDK-backed MCP server entrypoint.

Clone and install:

git clone https://github.com/ch998244353/Thread-Contract-mcp.git threadcontract-mcp
cd threadcontract-mcp
python -m pip install -e .

Run the handwritten stdio MCP server:

threadcontract-mcp

Run the local Web UI:

threadcontract-web --port 8765

Open:

http://127.0.0.1:8765/

By default, Thread Contract stores SQLite data at:

~/.codex/threadcontract.sqlite3

Override it with THREADCONTRACT_DB:

$env:THREADCONTRACT_DB = "$HOME\.codex\threadcontract-dev.sqlite3"

Use With Codex

For source/plugin development, this repository includes:

.codex-plugin/plugin.json
.codex-mcp.json
hooks/codex_hooks.json
hooks/user_prompt_submit.py

Use the helper script to add this checkout as a local Codex plugin marketplace:

.\scripts\install-codex-plugin.ps1

Then restart Codex, install or enable the Thread Contract plugin from the local marketplace, open /hooks, review the bundled hook, and trust it. Codex does not run non-managed plugin hooks until the current hook definition is trusted.

For MCP-only setup, add this to ~/.codex/config.toml after installing the package:

[mcp_servers.threadcontract]
command = "threadcontract-mcp"
enabled = true
startup_timeout_sec = 10
tool_timeout_sec = 30
enabled_tools = [
  "threadcontract_open_turn",
  "threadcontract_commit_turn_list",
  "threadcontract_list_turn",
  "show_threadcontract_list",
  "threadcontract_add_turn_item",
  "threadcontract_update_turn_item",
  "threadcontract_copy_list_text",
  "threadcontract_get_list_web_url",
  "threadcontract_delete_thread_list",
]

See docs/codex-adapter.md and docs/mcp-config.md.

Use With Claude Code

The Claude Code plugin files live at the repository root:

.claude-plugin/plugin.json
.mcp.json
hooks/claude_hooks.json
hooks/claude_user_prompt_submit.py

Validate locally:

claude plugin validate . --strict

Run a development session:

claude --plugin-dir .

Use As Python SDK

The importable SDK is for local agent runtimes that want Thread Contract without MCP:

from threadcontract_sdk import ThreadContractClient

client = ThreadContractClient(db_path="threadcontract.sqlite3")
thread = client.open_thread(
    thread_id="thread-a",
    workspace="/path/to/repo",
    user_message="start",
)
client.add_item(thread=thread, content="Answer with the conclusion first.")
client.commit_items(thread=thread)

context = client.build_context(thread=thread, user_message="next request")
print(context)

The stable public SDK exports only:

• ThreadContractClient
• ThreadContractThread

What It Provides

• Stdio MCP server with Thread Contract management tools.
• Codex plugin manifest, bundled MCP config, and UserPromptSubmit hook.
• Claude Code plugin manifest, bundled MCP config, and hook adapter.
• Local Web UI for viewing and editing a Thread Contract list.
• Importable Python SDK for custom local agent runtimes.
• SQLite storage with cleanup for stale lists and capped local data size.

The server exposes these MCP tools:

• threadcontract_open_turn
• threadcontract_commit_turn_list
• threadcontract_list_turn
• show_threadcontract_list
• threadcontract_add_turn_item
• threadcontract_update_turn_item
• threadcontract_copy_list_text
• threadcontract_get_list_web_url
• threadcontract_delete_thread_list

Alternate MCP SDK Server

The default plugin config uses src/server.py, a small handwritten stdio MCP server with no runtime dependency outside the standard library.

An alternate server using the MCP Python SDK is available:

python -m pip install -e ".[sdk-server]"
threadcontract-mcp-sdk-server

Repository Layout

threadcontract-mcp/
  .codex-plugin/plugin.json      # Codex plugin manifest
  .claude-plugin/plugin.json     # Claude Code plugin manifest
  .codex-mcp.json                # Codex bundled MCP server config
  .mcp.json                      # Claude Code bundled MCP server config
  hooks/                         # Codex and Claude Code hook adapters
  src/                           # MCP server, service layer, Web API, SDK
  web/                           # Source Web UI assets for plugin/source runs
  docs/                          # Installation, architecture, security docs
  examples/                      # MCP, Codex, Claude Code, and SDK examples
  scripts/                       # Local install helpers
  tests/                         # Unit, hook, stdio, Web UI, and acceptance tests

Tests

Run the unit suite and acceptance smoke:

python -m unittest discover -s tests -v
python tests/acceptance.py

Build verification:

python -m pip install -e ".[dev]"
python -m build

Security And Privacy

Thread Contract is local-first. It stores explicit user-created rules and audit events in SQLite. It does not capture conversation history automatically and it does not create cross-thread long-term memory.

Hooks can inject extra context before a prompt is sent to the model. Review and trust hook code before enabling it. See SECURITY.md and docs/security.md.

Documentation

• docs/install.md
• docs/quickstart.md
• docs/mcp-config.md
• docs/codex-adapter.md
• docs/architecture.md
• docs/security.md

License

MIT. See LICENSE.