repiscope 0.2.2

A periscope for your repos - read-only MCP server for sibling repository context

Repiscope

A periscope for your repos — see everything, touch nothing.

Repiscope is a read-only MCP server that gives your coding agent (Claude Code, Cursor, or any MCP client) awareness of the sibling repositories next to the one it's working in — without ever letting it modify them.

Why

I built a personal assistant to help me decide where my time goes: for that it needs to know the real state of every project — what changed, what stalled, what the next step is. So it has to see all my repos. But telling an agent "don't touch anything" is a request, not a guarantee. Repiscope makes it a guarantee: the server exposes zero write tools, so the agent structurally cannot modify your repos. And the same periscope helps any coding agent working in project A that needs to know how a part of project B works.

Sandboxes make this worse, not better: mine (rightly) stops the agent from even reading outside the repo it started in without asking. Widening the sandbox would grant write access too. Repiscope is the third way — the agent gets structured, read-only sight of every sibling repo through one MCP server, and the sandbox stays tight.

See it in action

You're working in project-a and need to pull data from another project's API. Instead of you digging through that codebase, the agent asks Repiscope directly:

You:    Use Repiscope to find out what kind of data I can retrieve
        from billing-api through its API.

Agent:  (calls list_projects → sees "billing-api")
        (calls project_overview "billing-api" → spots src/routes/)
        (calls search "route" project="billing-api")
        (calls read_file "billing-api" "src/routes/invoices.py")

        billing-api exposes three endpoints: /invoices (list, filterable
        by customer and date), /invoices/{id} (full invoice with line
        items), and /customers/{id}/balance (current balance). All
        responses are JSON; auth is a bearer token.

The agent explored a repo it has no ability to write to. No copy-paste, no "please don't edit anything," no risk.

Tools

Tool	Input	Returns
list_projects()	—	every sibling repo + one-line description
project_overview(project)	repo name	full overview: purpose, stack, structure, recent commits
search(query, project?)	text, optional repo	files & lines matching the query
read_file(project, path)	repo + file path	full file contents (size-capped)
store_summary(project, summary)	repo + your text	caches an agent-written summary (see below)

How it stays fresh

Overviews are cached as markdown and refreshed lazily: on each call Repiscope compares the repo's current git commit hash against the one recorded when the overview was built. Same hash → serve the cache. Different → rebuild just that repo's overview. No cron, no daemons.

Borrowed intelligence

Repiscope has no LLM of its own — no API key, no model calls, zero cost. But it talks to LLMs all day, so it borrows them: when an overview has no fresh agent-written summary, it ends with a note asking the calling agent to write one and hand it back via store_summary. The summary then opens every future overview of that project — written by one agent, read by all the next — until the repo's next commit marks it outdated and the cycle repeats.

Security by architecture

Repiscope is built so that the safe behaviour is not a promise — it's the only behaviour possible:

• Zero repo-write tools. The server exposes no tool that can create, edit or delete anything inside your repositories. The one tool that accepts data, store_summary, can only write to Repiscope's own cache in ~/.cache/repiscope. An agent cannot misuse a capability that doesn't exist.
• Secrets are invisible. A single filter (privacy.py) is enforced by every tool: private keys, certificates (.pem, .pfx, .p12, …), .env* files, keystores, and anything named like a credential never appear in overviews, trees, search results or file reads. Honest limit: the filter hides sensitive files — it does not scrub mentions of e.g. a password pasted inside an ordinary text file.
• Symlinks can't smuggle. A cloned repo is untrusted content — it may contain a symlink like notes.txt → ~/.ssh/id_rsa. Anything whose real location falls outside the project is invisible to every tool, the secret filter also checks a link's real target, and path traversal (../) is refused.
• You define the perimeter. Repiscope only sees the folder you explicitly pass (--root), and --exclude makes chosen repos fully invisible — they can't even be resolved by name.
• It leaves no trace. Overview caches live in ~/.cache/repiscope, never inside your repositories.

Every claim above is enforced by the test suite in tests/ — clone the repo and run pytest to check them yourself.

Quick start

pip install repiscope
claude mcp add repiscope --scope user -- repiscope --root ~/your/projects/folder

That's it — point --root at the folder containing your repos (not a repo itself). Optionally hide repos with --exclude repo-a --exclude repo-b. Works with any MCP client; for Claude Desktop there's also a one-click .mcpb bundle (build it with mcpb/build.sh).

From source instead:

git clone https://github.com/3xpr1ment/repiscope.git
cd repiscope
python -m venv .venv && .venv/bin/pip install -e .[dev]
.venv/bin/pytest   # the security claims, as executable proof

Limitations

Honesty section — what Repiscope deliberately does not do:

• The secret filter works at file level. Sensitive files are invisible, but a password pasted inside an ordinary notes.md will not be scrubbed. The perimeter is yours: only point --root at folders you are comfortable showing to your agent — whatever the tools can see, your LLM provider will see too.
• Search is deliberately dumb. Case-insensitive substring match, capped results, no index, no regex. The calling LLM supplies the intelligence at both ends; for heavy code search, use a real code-search tool.
• Overviews are mechanical. Without an agent-written summary they are README excerpts, language stats and git logs — useful, not insightful. The insight arrives once your agents start leaving summaries behind.
• Read-only cuts both ways. There is no refresh tool to call: caches refresh lazily on the next commit, and stale summaries are served marked as stale until an agent writes a new one.
• Python ≥ 3.11, developed and tested on macOS; Linux should behave identically, Windows symlink semantics are untested.

Status

v0.2.2 — working and dogfooded daily. Four read-only tools plus borrowed-LLM summaries, lazy cache refresh, sensitive-file filtering, and a test suite proving the security claims (path traversal, symlink escapes, secret filtering — see tests/). API may still change.

How this was built

To be completely clear about authorship: I am not an engineer. Every architecture decision in Repiscope is mine — what it does, what it refuses to do, where the security gates live — but the coding itself is done by Claude (Anthropic's Fable model). My rule for the collaboration: nothing goes in that I don't understand. The commit history carries the co-authorship openly, commit by commit.

License

MIT

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mcp-name: io.github.3xpr1ment/repiscope