Prime Agent for VS Code

Chat with Prime Agent directly from VS Code. The extension runs the Prime Agent CLI as a headless RPC subprocess (prime-agent --mode rpc) and renders the full agent stream — assistant text, thinking, and every tool call — in a sidebar chat view.

The agent keeps its own runtime: daemon-backed sessions, skills, the persistent IPython kernel, subagents, schedules, and the continual harness all behave exactly as in the terminal client. The extension is a UI over the RPC protocol, not a reimplementation.

Community project. Built and published by sirouk; it is not an official Prime Intellect release and is not affiliated with them. The Prime Agent name and the butterfly mark are Prime Intellect's, used here to identify the CLI this extension drives.

Install

From the Marketplace

Extensions view (Ctrl+Shift+X / Cmd+Shift+X) → search Prime Agent, or from a terminal:

code --install-extension sirouk.prime-agent-vscode

Listing: marketplace.visualstudio.com/items?itemName=sirouk.prime-agent-vscode

From source

One-liner — clones to a temp dir, builds, installs, cleans up:

curl -fsSL https://raw.githubusercontent.com/sirouk/prime-agent-vscode/master/install.sh | sh

Manual:

git clone https://github.com/sirouk/prime-agent-vscode
cd prime-agent-vscode
npm ci
npm run package
code --install-extension prime-agent-vscode-<version>.vsix

Building from source requires git, node >= 20, npm, and the code CLI on PATH (macOS: run Shell Command: Install 'code' command in PATH from the Command Palette). The extension usually activates without a window reload; otherwise run Developer: Reload Window.

Features

• Streaming chat with markdown rendering, collapsible thinking blocks, and live tool-call cards carrying the call itself and every output section, each with its own copy button. The CLI's default toolset is ipython alone, so a shell run arrives as a %%bash cell: those get terminal chrome and copy as shell, Python cells copy as Python, and the collapsed card shows the same one-line cell preview the terminal client shows.
• Honest connection state: the composer arms only once the agent has actually answered an RPC round-trip — not merely when a process exists. If prime-agent can't be reached (never installed, wrong primeAgent.command, or a binary that starts and then never replies), a dismissible card names the reason and offers the install guide and a Retry.
• Prime Intellect accent: deep-neutral surfaces with the signature green used sparingly — the butterfly mark, the send button, live indicators. Respects light and dark themes.
• Live sessions & terminal parity: sessions stay resident after you close the view; opening a session that is already live in a terminal attaches through the daemon so both clients see and steer the same stream (read-only observe when the daemon can't attach, and Stop is addressed to the session that owns the run).
• Subagents: collapsible strip above the composer lists the session's subagents with activity pulse — running, idle, or (in their own collapsed "Historical" group) finished; browse inside any of them, the one you are reading stays listed and highlighted, siblings stay one click away, and back-to-parent returns.
• Thread diffs: collapsible "Changes" panel above the composer stitches the real diff payloads Prime Agent publishes when its bundled edit skill rewrites a file — for the current thread and its subagents, per file, expandable, with an Open-file shortcut and the contributing subagent named on each hunk. It rebuilds from the session's own history, so resuming a thread or stepping back out of a subagent keeps the list intact. Nothing is inferred: a file the agent rewrote from a shell or raw Python cell publishes no diff and therefore appears only in the coarse changed-files strip above the transcript, which the panel says out loud.
• Steer while working: send messages while the agent runs; the steer/queue pill in the composer rail chooses mid-turn steering or end-of-run delivery. Stop button aborts the run.
• Editor context: + attach menu — mention files and folders (@ with indexed autocomplete; folders carry a trailing /), attach the active file or the current selection, or attach images on vision-capable models. Paste and drag-drop work too, and are gently refused on text-only models. Mentions render inline-styled inside the composer and as clickable chips in your messages; folders reveal in the Explorer.
• Composer rail: searchable model menu holds ★ favorites (persisted), reasoning and vision (img) badges, context-window sizes, and full model ids on hover. Immediately right of the model pill, a brain pill opens the thinking levels — scoped to what the selected model actually supports, read from the model's own level map, so it never offers a level the agent would silently swap. Next to it: the steer/queue toggle (default via primeAgent.defaultStreamingBehavior) and a live context meter you click to set the per-session auto-compact threshold override — the slider runs from 20% to the agent's own default ceiling (at least 80%, higher on a big context window) and reads out the token count each percentage means.
• Session control: history grouped by This workspace / Other folders, with an instant client-side filter and a host-side search of the conversations themselves — rows found that way carry the snippet that matched. A pulsing dot marks a session that is running right now (including the one you are in). Hover a row for stop, archive, rename, and delete; archive and delete ask for a one-tap inline confirm, delete refuses a session that is live in another client, and archive keeps the transcript and resumability while dropping the row from the list. New session and history live in the header; compact, export, and agent restart in the ⋯ menu.
• Export & copy: Export chat… offers Markdown with summarized tool calls, Markdown without them, or the agent's own HTML transcript; the transcript header copies the whole conversation as Markdown. Per-reply, per-thinking, and per-tool-call copy buttons; fork the session from any user message (mirrors /fork); user-message footers show an estimated token count and the metered cost of the reply that message opened.
• Composer care: drafts are kept per session and survive reloads and session switches; selection preserves across collapse/expansion of thinking and tool cards; streaming follows the bottom by default but never fights your scrolling (jump-to-latest pill appears when you're reading up).

Requirements

• The prime-agent CLI installed and authenticated (/login in the terminal client, once).
• VS Code 1.90+.

If prime-agent is not on PATH, set primeAgent.command to an absolute path, e.g. /path/to/prime-agent/prime-agent.sh for a source checkout. When the extension can't reach the CLI it says so in the chat view and links the upstream install guide.

Settings

Commands

All under the Prime Agent: prefix, e.g. Prime Agent: Focus Chat, New Session, Compact Context, Export Chat…, Resume Recent Session…, Restart Agent Process, Add Selection to Chat, Add Active File to Chat, Open Chat in Editor Tab, Stop Agent.

Editor context menu: Prime Agent: Add Selection to Chat with a selection, Add Active File to Chat without one. Cmd+Alt+K sends the selection on macOS; on Windows and Linux use the context menu or bind Add Selection to Chat to a chord of your own (the shipped chord uses the meta key there, which the window manager usually swallows).

Header links: the butterfly / title opens the Prime Agent blog post; the ⋯ menu links to app.primeintellect.ai.

How it works

VS Code extension host                Prime Agent CLI
┌──────────────────────┐   JSONL/stdin   ┌────────────────────────┐
│ sidebar/editor webview│───────────────▶│ prime-agent --mode rpc │
│   (chat UI, markdown) │◀───────────────│  events: message_update │
│ SessionController     │   events/stdout│  tool_execution_*      │
│   RpcClient (JSONL)   │                │  extension_ui_request  │
└──────────────────────┘                └────────────────────────┘

• Commands/responses are correlated by id; framing splits on \n only (Unicode line separators are valid inside JSON strings — see docs/rpc.md in prime-agent).
• Extension UI requests (select, confirm, input, …) are answered with native VS Code quick picks, input boxes, and notifications.
• Session history is read from the daemon's own catalog when it answers, and from ~/.prime/agent/sessions/*.jsonl when it doesn't; both are filtered by workspace cwd and resuming uses the switch_session command.
• A session that is already live elsewhere is never driven over our own subprocess — RPC mode owns its session and cannot attach to one. For those, the extension speaks the daemon protocol itself over the daemon's socket (unix socket, named pipe on Windows), which is what makes attach — rather than a second, competing session — possible.

Development

TypeScript + esbuild, no framework, no runtime npm dependencies in the shipped bundle. The webview is hand-written TS compiled to a single media/main.js.

npm install
npm run compile        # esbuild: dist/extension.js + media/main.js (+ test bundles)
npm run typecheck      # tsc --noEmit
npm run test           # activation harness with a stubbed vscode module
npm run smoke          # spawns a real prime-agent --mode rpc and round-trips a prompt
npm run package        # produce prime-agent-vscode-<version>.vsix

Test layers:

• test/webview.test.mjs — happy-dom harness driving the built media/main.js (rendering, menus, history, streaming states). Fully headless.
• test/export-md.test.mjs — markdown export harness.
• test/thread-diffs.test.mjs — the "Changes" panel against real diff payloads.
• test/recent-sessions-tail.test.mjs — the on-disk history fallback (renames and archive entries that live at the tail of a session file).
• test/host-e2e.mjs — real SessionController + stubbed vscode vs. a real CLI.
• test/daemon-parity.mjs — CLI + extension on the same resident session, both seeing the same prompts and answers.
• test/smoke.mjs — RPC protocol round-trip (--session-dir temp store). Built from test/smoke.ts by esbuild; the bundle is generated, not committed.
• test/preview-shot.mjs — headless Chromium screenshots + DOM assertions.
• test/vscode-e2e.mjs — real-shell trace: Playwright drives actual VS Code (minimized window, throwaway --user-data-dir, extension loaded from the repo via --extensionDevelopmentPath). Covers the sidebar mount, tooltips, model/thinking menus, prompt round-trip, grouped history, session resume, the observe fallback for sessions already live elsewhere, and abort. Note: Electron can't run headless on macOS; the suite minimizes the window instead. Uninstall the packaged extension before running it so the dev-path build wins resolution.
• test/live-driver.mjs — persistent http driver on 127.0.0.1:7321 that keeps one backgrounded VS Code open and reloads the extension host in place for iterative runs. It exposes scenario endpoints (/scenario/menus-then-prompt, /scenario/stop-mid-run, /scenario/new-session, /scenario/resume-and-observe …), /eval?expr=… to evaluate expressions inside the webview, and /state for DOM status. Request a bogus scenario name to get the list.

Set PRIME_AGENT_VSCODE_LOG=/path/to/file to get the env-gated host debug log (spawn config, wire summaries, prompt lifecycle) — useful when diagnosing in the field.

To try it in VS Code without packaging: open this folder and press F5 to launch an Extension Development Host, or install the built .vsix via the Extensions view ("Install from VSIX…").

Cutting a release

./release.sh runs the full gate (clean tree, branch/remote alignment, version/tag consistency, the test battery) before it commits, tags, pushes, and creates the GitHub release. .github/workflows/publish.yml then publishes to the Marketplace on any GitHub release (and on manual dispatch). To enable publishing once:

1. Azure DevOps → Personal Access Token with scope Marketplace > Manage, all organizations.
2. GitHub → repo secrets: add VSCE_PAT with that value.

Privacy

The extension talks only to the local prime-agent process over stdio and reads sessions and workspace files on your machine. Everything else — providers, tools, skills, subagents — is the agent's own runtime, governed by your prime-agent configuration and the providers you choose there. Session history and favorites are stored locally (globalState + your ~/.prime/agent directory) and never leave the machine except through the model providers you configured.

License

MIT — copyright sirouk. See LICENSE. The butterfly mark and the Prime Agent name are Prime Intellect's trademarks, used here only to identify the CLI this extension drives.