OpenCode PR Auto-Signature Plugin

Automatically adds AI model signature to Pull Requests, Issues, and Commits created through OpenCode.

Features

• 🤖 Automatic Detection - Dynamically detects the AI model being used (Kimi, Claude, GPT, Gemini, etc.)
• 🔄 Self-Updating Model Names - names come from OpenRouter's live model catalogue, refreshed in the background at most once a day - no hardcoded list to go stale
• 📝 Smart Signature - Appends signature only to content that doesn't already have it
• 🔄 Update Support - Works with both creation and update operations
• 🎯 Multiple Tools - Supports GitHub MCP tools, MCP Docker tools, git CLI, and gh CLI
• 💻 Git Commits - Automatically signs commit messages
• 🔧 gh CLI - Supports gh pr create, gh issue create, comments, and reviews

Installation

From NPM (Recommended)

Add to your OpenCode config (~/.config/opencode/opencode.json or project-level opencode.json):

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": ["opencode-pr-signature"]
}

From a Local Checkout

The plugin is several modules under src/, so it is installed as a package rather than copied as a single file:

1. Clone this repository

2. Install the checkout into your OpenCode config directory:

   cd ~/.config/opencode && npm install /path/to/opencode-pr-signature

3. Reference it in opencode.json exactly as for the published package:

   {
     "$schema": "https://opencode.ai/config.json",
     "plugin": ["opencode-pr-signature"]
   }

4. Restart OpenCode

Usage

Once installed, the plugin works automatically. When OpenCode creates a Pull Request, Issue, or Commit, the signature will be appended:

PR/Issue Example

Your PR description here...

🤖 Generated with [OpenCode](https://opencode.ai) (Kimi K2.5)

Commit Example

feat: add new feature

🤖 Generated with [OpenCode](https://opencode.ai) (Claude 3.5 Sonnet)

Supported Operations

GitHub MCP Tools

• github_create_pull_request
• github_create_issue
• github_update_pull_request
• github_update_issue

MCP Docker Tools

• MCP_DOCKER_create_pull_request
• MCP_DOCKER_create_issue
• MCP_DOCKER_update_pull_request
• MCP_DOCKER_update_issue

Git CLI

• git commit -m "message", including the attached forms -m"message" and -mmessage
• git commit --message="message"
• git commit -F message.txt and git commit --file=message.txt
• git commit -F- fed by a heredoc, a pipe, a redirect or a here-string
• git commit --amend --no-edit

gh CLI (GitHub CLI)

• gh pr create
• gh issue create
• gh pr comment
• gh issue comment
• gh pr review

The body is signed whether it is written out — --body x, --body=x, -b x, -bx — or only produced when the command runs, as in --body "$PR_BODY" or --body "$(cat msg.md)". A body read from a file with --body-file is not signed; see below.

Model Names

Model names are not hardcoded. The plugin fetches OpenRouter's public model catalogue and uses it to render human-readable names — Kimi K2.5, GLM 5.3, Grok 4.6, and so on:

• the catalogue is cached on disk and refreshed in the background when the cache is older than 24 hours — never delaying or breaking a signature;
• cache location: ~/.config/opencode/cache/opencode-pr-signature/models.jsonl (or $XDG_CONFIG_HOME/opencode/... when set);
• offline, on first run, or with an unreadable cache, names fall back to a nicely formatted version of the raw model ID;
• models OpenRouter does not carry (direct-vendor APIs, local runtimes) always use that fallback.

How It Works

1. Model Detection: The plugin listens to chat messages to detect which AI model is currently in use. The display name comes from a locally cached copy of OpenRouter's model catalogue, refreshed in the background when the cache is older than 24 hours (see Model Names)

2. Tool Interception: Using the tool.execute.before hook, it intercepts:

   • GitHub MCP tool calls (PR/Issue creation and updates)
   • Bash commands (git commit, gh pr create, etc.)

3. Signature Injection: Before the tool executes, it appends the signature. Where the text is written in the command, it is edited directly:

   • For MCP tools: modifies the body argument
   • For git commit -m: adds an additional -m flag (git concatenates multiple -m with blank lines)
   • For git commit -F- with a heredoc: appends the signature to the heredoc body, in place
   • For a gh --body written out in full: rewrites that argument

   Where the text only exists once the command runs — a message file, a pipe, a redirect, --amend --no-edit, a gh body held in a variable — the plugin adds a stage that reads the message at that moment and hands the signed result on:

   git commit -F msg.txt
   # becomes
   ( … cat -- msg.txt … ) | git commit -F -
   
   gh pr create --body "$PR_BODY"
   # becomes
   gh pr create --body "$( … "$PR_BODY" … )"

   The source is read exactly once and never written to, so a message file, a producer command or a $(…) body behaves as it did before. A commit whose message arrives on standard input keeps whatever was feeding it: the redirection or pipe moves onto the stage, and git reads the stage.

4. Duplicate Prevention: Checks if signature already exists to avoid duplicates — in the command for text written out, and at run time for text that is not. An empty or blank message stays empty, so git still refuses the commit.

What the Plugin Will Not Sign

Some commands are left exactly as you wrote them, and then behave as if the plugin were not installed. No error, no signature — because guessing at a commit message means committing the wrong one, and a missing signature is easier to live with than a lost message.

Not signed:

• A message you have not written yet — git commit and git commit --amend without a message option open an editor. There is nothing to sign until you have typed it, and supplying a message would suppress the editor you asked for.
• A message reused from another commit — -C, -c, --reuse-message, --reedit-message. These copy the author and the author date along with the message, and moving the message onto -F would quietly reset both to whoever is committing now.
• --squash and --fixup — those messages exist only until the rebase that consumes them.
• A message git would refuse anyway — git commit -m "". Signing it would turn the refusal into a commit whose whole message is the signature.
• A gh --body-file — reading the file inside the argument would discard whether the read succeeded, so a mistyped filename would become an empty body and a gh run that reported success. Use --body "$(cat msg.md)", which is signed.
• git commit -F- with nothing visible feeding standard input, and gh --body-file -, which reads standard input as well.
• A message file whose command is already downstream of a pipe — the producer expects git to read its output.
• A path that names more than one file — git commit -F *.txt. git takes the first match as the message and the rest as pathspecs; one reader cannot stand in for that.
• A command the plugin cannot parse with certainty — unbalanced quotes, an option quoted as a whole ("-Fmsg.txt"), -m mixed with -F, more than one input redirection, a redirection of a descriptor other than standard input, or a git commit that appears only inside another command's argument.

Configuration

Works out of the box. Two things are worth knowing:

Network. At most once a day, the plugin makes one background GET request to openrouter.ai/api/v1/models — no API key, no account, nothing else is sent — to refresh its model-name cache. Offline, it silently keeps the last cache, or the formatted-ID fallback when there is none.

Options. Via the tuple form of the plugin config:

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": [
    ["opencode-pr-signature", { "cachePath": "/custom/path/models.jsonl" }]
  ]
}

• cachePath — where the model cache is stored (default: ~/.config/opencode/cache/opencode-pr-signature/models.jsonl)

Development

# Install dependencies
bun install

# Type check
bun run typecheck

# Run the tests
bun test

The tests execute the rewritten commands for real, in throwaway git repositories, through /bin/sh — they need git and a POSIX shell on PATH. The suite is fully offline: network access is always injected or fixtured, never real.

License

Apache 2.0 - See LICENSE for details.

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

Support

• OpenCode Documentation
• OpenCode Discord
• GitHub Issues

Made with ❤️ for the OpenCode community