Nimbus — On-Call & Incident Agent for VS Code

A private, local-first agent for on-call and platform engineers. It answers from your own indexed context — incidents, deploys, ownership, code — and keeps a verifiable record of what it does off your machine. All running locally; your data never leaves the box except through actions you can see and prove.

Built for incident response & platform work

Structured, grounded answers via the built-in Chat participant — not generic prompts:

• /incident — what's going on right now: a catch-up brief across the services you own.
• /deploys <service> — DORA metrics (deploy frequency, lead time, change-fail rate, MTTR).
• /owns <file|service|topic> — who owns it, from your indexed history.
• /blast <file|PR> — blast radius: what a change touches downstream.

Each degrades honestly — an empty brief tells you why (missing connector, no data), never a confident guess.

A verifiable record of what the agent does off your machine

Nimbus keeps a signed, hash-chained egress ledger of every outbound action the agent dispatches — one row, appended before the action leaves. Inspect it, verify the chain, and export a signed proof for any time window, all locally. A claim no cloud assistant can make, because completeness for the agent's actions can only be established at the point of departure, under your control.

Scope, stated plainly: this records the agent's dispatched actions, not raw network traffic. It is not a firewall or host DLP and does not capture sockets or HTTP made outside the agent (the OS, other processes, or an unsandboxed third-party MCP server). It is a provable record of what the agent did — not a claim about every byte that left the machine.

Preview what leaves — before it does

The ledger answers "what left?". The pre-flight gate answers "should this leave at all?", while you can still say no. Every agent-bound path routes through one seam that renders exactly what would be sent — file names only, never directory or repository paths — and can refuse to send it.

Where the extension assembles the context for you, you get the final say: Quick Ask and the dev-workflow trio show a manifest of the payload (how many files, how many characters, what was left out and why) with Show full text to read the exact bytes in a tab, and Always send … here to stop asking per surface, per workspace. nimbus_ask confirms inline when another chat extension calls it. The Ask panel and @nimbus participant send text you typed yourself, so they record without interrupting.

It also warns when the payload contains an absolute path from your machine — Nimbus never adds one, but your own code and comments sometimes do. In Restricted Mode a stored Always send is ignored and you are asked again, since that is precisely when you wanted to be. The gate needs no Gateway connection: it works while disconnected. Nimbus: Show Last Outbound Payload replays the last send verbatim, and Nimbus: Reset Egress Preview Prompts clears the stored choices.

Everything else it does

• Ask — chat with the Nimbus agent in a side panel; responses stream token-by-token, and a Stop button cancels a long generation cleanly while keeping the partial reply.
• Attach context to Ask — pull a workspace file, an editor selection, or a local-index item into a question, from a composer button, the editor's Attach Selection to Ask, or Attach to Ask on an Index sidebar row. The composer shows exactly what will be sent: a chip per attachment with its resolved size, or the reason it wasn't sent — a possibly-secret or binary file is refused outright, an oversized one is clamped and says how much of it made the cut. isSecretPath matches file names, not contents — an API key pasted into an ordinary source file is not detected, the same limitation Review Changes ships with. Attachments last for the whole session, so a follow-up question keeps them, and each sent question keeps its own permanent record of what it carried.
• @nimbus Chat participant — also works as a general assistant: free-form questions can pull in #file context (or your selection), answers stream token-by-token, and replies include clickable citations back to local-index sources. Explain / Fix / Review / Docstring / Write tests live as Quick Ask presets rather than slash commands.
• Language Model tools — other chat extensions and agents can call Nimbus as a tool: nimbus_search (ranked search over your private local index) and nimbus_ask (a one-shot answer from your local agent), referenceable in a prompt as #nimbusSearch / #nimbusAsk.
• Quick Ask — ask about a selection (or the whole file) and get a one-shot answer in a read-only tab, without opening the chat panel.
• Search — live ranked (semantic + keyword) search over your local Nimbus index; results update as you type, and selecting one opens its source (or notifies you when it has none). Search Selection seeds it from the editor.
• Find related — from a selection or an Index sidebar item, pivot to the local knowledge around it (ranked search that excludes the item itself).
• Selection-aware — right-click a selection to Ask About Selection, Search Selection, or Find Related.
• Dev-workflow trio — Generate Commit Message drafts a message from your staged diff, in your repository's own commit style, into the Source Control input box; Review Changes reviews all local changes (staged and unstaged) in a findings tab that also names what wasn't reviewed (too large, possibly secret, binary or non-textual changes, untracked); Generate Tests and Generate Docstrings work over an editor selection, opening an untitled test buffer or a docstring diff. Output is always a suggestion — nothing is written to disk or applied automatically.
• Diagnostic actions — the lightbulb on an error or warning offers up to three Nimbus actions: Explain this problem, Suggest a fix (shown as a diff you apply yourself — nothing is ever written for you), and Find prior occurrences, which searches your local index for the same error and reaches no model at all. Where a line carries several diagnostics — a compiler error and a lint warning, say — one is chosen, so the lightbulb gains at most three entries rather than three per diagnostic. Toggle with nimbus.diagnostics.showCodeActions.
• Blame on hover — hover any line to see who last changed it, when, the commit subject, and the linked PR or ticket, with a Why? → link into the full "Why is this here?" brief. Reads local git and the local index only — no model is involved. Toggle with nimbus.briefs.showHoverBlame.
• Built-in briefs — Why is this here?, Who knew this code? and Who else is touching this? from the editor context menu, plus Team huddle, Is this idle? and Safe to deploy? from the palette and the Agents view.
• Workflows — run or dry-run a saved workflow from the editor: per-step output streams as it goes, and a cancel lands at the next step boundary.
• Context panel — a sidebar view that follows whatever you're looking at: the errors and warnings in the current file, the branch and a count of files not yet committed (staged and unstaged together) in the repository that file belongs to, who last touched the line under your cursor, what else in your local index looks related, and the built-in briefs that fit right now, pre-filled with the file and line so you don't retype them. The last two ask your local Gateway automatically, on a short delay after you stop moving — no click needed — sending the repository-relative path, the cursor line, and the selected text when there is one. Neither call reaches a model (they are the same git-blame and local-index lookups as Blame on hover and Find related), which is why they don't raise a pre-flight preview; clicking a brief does, exactly as everywhere else. Collapse the view and it stops collecting entirely; a nimbus.context.enabled setting switches it off while it stays open — the view stays visible and says it's off rather than going blank.
• Connectors — a sidebar view of every registered source: its health, item count and last sync, with recent sync attempts and health-state changes underneath each row. Act on one without leaving the editor — sync now, pause or resume, change the interval or index depth, re-index, authenticate, or remove it. Credentials are typed into a masked prompt and handed straight to your local Gateway, which owns them; the extension never stores, caches or logs a credential. Adding an MCP source and removing a connector need your consent, and a request you decline (or leave unanswered) is reported as a decision, never as a failure. Registering a built-in connector still needs the Nimbus CLI — no RPC exposes it yet.
• Nimbus sidebar — activity-bar views for Context, Connectors, Sessions (with chat resume), the local Index, Agents, and Workflows.
• Audit & Egress ledgers — inspect what the agent did and everything it sent off-device; verify the egress hash-chain and export a signed proof for any time window, all locally. A status-bar badge (shown while connected, on by default) displays the egress row count with a ledger-live ✓ — click to open the ledger, or toggle it with nimbus.egress.showStatusBarBadge.
• Connection troubleshooter — Nimbus: Troubleshoot Connection explains why you're disconnected and offers one-click fixes (start the Gateway, reconnect, open logs, or edit the socket path).
• Get Started walkthrough — a first-run walkthrough (Nimbus: Open Walkthrough, also on the Welcome page) that guides you from connecting the Gateway through Ask, Search, and Quick Ask.
• Restricted Mode aware — the extension still works in an untrusted workspace; only the workspace-level nimbus.socketPath and nimbus.autoStartGateway settings are ignored, so a workspace can't redirect the IPC socket or spawn a process.

Install

• VS Code Marketplace: ext install nimbus-agent.nimbus-vscode
• Open VSX (Cursor, VSCodium): ext install nimbus-agent.nimbus-vscode
• Manual: download the .vsix from the latest release and run code --install-extension nimbus-<ver>.vsix.

Verifying a release

Starting with the next release after v0.5.0, every release attaches a build provenance attestation to the .vsix on the GitHub Release — this is an attestation, not a signature on the file itself. To verify a .vsix from one of those releases was built by this repository's publish workflow:

gh attestation verify nimbus-<version>.vsix --repo nimbus-agent/nimbus-vscode

This covers the .vsix attached to the GitHub Release. The Visual Studio Marketplace performs its own repository signing, which VS Code verifies at install time; that is a separate mechanism and this attestation is not surfaced through it.

Quickstart

Run Nimbus: Ask from the command palette, or right-click a selection in the editor and choose Ask About Selection / Search Selection. The extension connects to your local Nimbus Gateway automatically (enable nimbus.autoStartGateway to have it start the Gateway for you).

First time? Run Nimbus: Open Walkthrough (or open it from the Get Started / Welcome page) for a guided setup — connect the Gateway, then try Ask, Search, and Quick Ask.

Requires

A running Nimbus Gateway. See https://nimbus-agent.dev/user-guide/install/ for setup.

Settings

See docs/settings.md for the full reference.

Contributing

See CONTRIBUTING.md. This repository was extracted from the Nimbus monorepo; it consumes @nimbus-dev/client from npm and releases independently of the Gateway.

See also

• Documentation — architecture, development, settings, and release docs
• Roadmap — where the extension is going, phased by SDK-readiness
• Nimbus User Guide
• Nimbus — the Gateway this extension talks to
• Ask a question — the shared Nimbus Discussions board. If something is broken rather than unclear, run Nimbus: Troubleshoot Connection first, then report it

On the roadmap (not yet shipped)

• The rest of the why lens — the hover itself ships today (see Blame on hover above). Still to come: the incident a line responded to, and what breaks if you change it. Both are built on the gateway and reachable through the client (agents.why/agents.whyPeek).

See the Nimbus roadmap for the full plan.

License

MIT