reasonix-plugin-git-context

An external MCP (Model Context Protocol) plugin for DeepSeek-Reasonix that gives the agent read-only git context tools — blame, log, show, diff, file history, and a one-shot PR-context summary — over stdio JSON-RPC.

By Kashif Mahi (@kashifmahi).

It is a standalone npm package that depends on Reasonix as a host; it is not part of Reasonix core. Reasonix loads it as a subprocess declared in reasonix.toml, exactly like any other MCP server (see the SPEC's §3.3 Plugins).

All tools are declared with annotations.readOnlyHint: true, so Reasonix treats them as safe readers — eligible for parallel-batch dispatch and its reader permission default. Inside Reasonix they appear namespaced as mcp__gitcontext__<tool>.

Tools

| Tool | What it does | | --- | --- | | git_blame | Who last changed each line of a file (optional line range / revision). | | git_log | Recent commits; optionally scoped to a path, revision range, or author. | | git_show | A commit's message + diffstat (and patch unless stat_only). | | git_diff | Working-tree diff, or a diff between two revisions. | | git_file_history | Commit history for one file, following renames. | | git_pickaxe | Find commits that introduced/removed a string (-S) or matched a regex (-G). | | git_pr_context | Branch-as-PR summary: base, merge-base, commits ahead, changed files. |

Install

npm install -g reasonix-plugin-git-context
# or run on demand without installing:
npx reasonix-plugin-git-context

Requires Node ≥ 18 and git on PATH.

Wire it into Reasonix

Add this to your project's reasonix.toml (or the user-global config.toml). The [[plugins]] schema and ${VAR} expansion are defined in the Reasonix SPEC §5:

[[plugins]]
name    = "gitcontext"          # type defaults to "stdio"
command = "npx"
args    = ["reasonix-plugin-git-context"]
# env   = { GIT_CONTEXT_ROOT = "${GIT_CONTEXT_ROOT:-}" }   # optional: pin the repo dir

If you installed it globally you can skip npx:

[[plugins]]
name    = "gitcontext"
command = "reasonix-plugin-git-context"
args    = []

Reasonix connects over stdio, runs the MCP handshake (initialize → notifications/initialized → tools/list), and the tools become available in-session as mcp__gitcontext__git_blame, mcp__gitcontext__git_pr_context, etc. Type /mcp in the Reasonix chat TUI to confirm the server connected and see its tool count.

Configuration

| Env var | Purpose | Default | | --- | --- | --- | | GIT_CONTEXT_ROOT | Repository directory the tools operate in. | current working directory |

Every tool also accepts an optional cwd argument that overrides GIT_CONTEXT_ROOT for a single call.

Example

Once wired in, you can ask Reasonix things like:

• "Blame lines 40–80 of internal/agent/loop.go and tell me who owns that code."
• "Give me the PR context for this branch against main."
• "Show the history of README.md and summarize how the install steps changed."

Safety

• git is invoked as an argv array (never through a shell), so there is no shell-injection surface.
• Revision/path arguments beginning with - are rejected to prevent git option-injection.
• Output is capped (~60k chars) and each call has a 20s timeout so a large repo cannot overwhelm the session context or hang the agent.
• The server is strictly read-only — it never writes to the repository.

Development

npm install
npm run build      # tsc -> dist/
npm test           # builds, then runs a real stdio JSON-RPC round-trip (node --test)
npm run typecheck

The test in test/roundtrip.test.mjs spins up a throwaway git repo, launches the built server, performs the full MCP handshake over stdio, and calls the tools — the same path Reasonix uses.

Author

Built and maintained by Kashif Mahi — Senior Web & Blockchain developer.

• GitHub: @kashifmahi
• LinkedIn: kashifmahi
• X/Twitter: @kashifmahi271

Contributions and issues welcome at github.com/kashifmahi/reasonix-plugin-git-context.

License

MIT © Kashif Mahi — matches upstream DeepSeek-Reasonix.