sema for VS Code

A UI for sema — semantic code search, reuse checks, and a codebase-aware chat panel, right inside the editor. Chat with your code through four providers:

• Claude Code (local) and Codex (local) — reuse the CLIs you already have installed and logged in; no API key needed. They read (and, in Agent mode, edit) your repository directly.
• Claude (Anthropic API) and OpenAI — bring your own API key; sema retrieves the most relevant code and injects it as context (RAG).

The extension shells out to the sema CLI (--json mode) for search and retrieval, and runs every provider from the extension host — so API keys never reach webview/page context.

Installation

sema has two parts: the sema CLI (the local indexer this extension drives) and the VS Code extension itself. Install the CLI first.

1. Install the sema CLI

The extension drives the sema CLI, so install it first:

pip install sema-mcp        # or: uv tool install sema-mcp
sema --version              # verify

git clone https://github.com/masihmoloodian/sema.git
cd sema
uv venv --python 3.12 .venv
uv pip install -e ".[dev]"
echo "export PATH=\"$(pwd)/.venv/bin:\$PATH\"" >> ~/.zshrc && source ~/.zshrc
sema --version

Requires Python 3.11+. Full guide: docs/installation.md.

If VS Code can't find sema: apps launched from the Dock/Finder often don't inherit your shell PATH. The reliable fix is to point the extension straight at the binary — run which sema and set sema.binaryPath to that absolute path (see step 4).

2. Chat prerequisites

For the chat panel you need at least one of:

• the Claude Code and/or Codex CLI installed and signed in (recommended — no key management, and they can edit files in Agent mode). Not signed in yet? Just click Log in in the panel — it runs the CLI's own browser sign-in. Or:
• an Anthropic and/or OpenAI API key (added from the panel — stored in VS Code SecretStorage, never in settings).

3. Install the extension (.vsix)

You install a packaged sema-codebase-chat-<version>.vsix file (e.g. sema-codebase-chat-0.1.0.vsix). Two ways:

From the VS Code UI

1. Open the Extensions view (⇧⌘X / Ctrl+Shift+X).
2. Click the ⋯ menu at the top of the view → Install from VSIX…
3. Select the .vsix file.

From the command line (needs the code command — in VS Code run Shell Command: Install 'code' command in PATH first if it's missing):

code --install-extension sema-codebase-chat-0.1.0.vsix

Reload VS Code when prompted. A sema icon appears in the Activity Bar.

Don't have a .vsix? Build one from source — see Build from source below.

4. First-run setup

1. Open your project folder (File → Open Folder…). sema works against the open folder; chat providers that read the repo use the enclosing git root.
2. Point the extension at the sema binary if VS Code can't find it on its PATH: run which sema and set sema.binaryPath to that absolute path. See Configuration.
3. Build the index. Open the sema view → Manage → Re-index (or run sema index . in a terminal). The chat panel can also build it automatically the first time you turn the index toggle on.
4. Open the Chat view, pick a provider/model, and start typing.

Features

• Chat — a Cursor-style panel with provider, model, and reasoning-effort pickers, plus Ask (read-only) / Agent (can edit files) modes. Local CLI providers stream thinking and tool activity like their terminal apps do, and keep per-session memory across turns. A Log in button signs you into Claude Code / Codex from the panel (via each CLI's own browser flow) and shows your sign-in state; if a message fails because you're not signed in, a one-click Log in prompt appears. Each chat is one session; New chat starts a fresh one. Toggle index on to inject sema's semantic context (RAG) — useful for API providers, which can't read files themselves.
• Manage — index status, chunk/file counts, model, last-updated time, index path, the sema binary in use, Claude Code / Codex registration, a file watch toggle, and the current chat session's token usage and estimated cost. Plus one-click actions: Re-index, Re-index (reset), register/unregister, watch, doctor.
• Search (sema: Search code) — semantic search; click a result to jump to the definition.
• Reuse (sema: Check reuse) — describe what you're about to build; sema tells you whether it already exists and lists candidates.
• Status bar — index freshness (chunks / files / age); warns when stale.

Configuration

Build from source

cd vscode-extension
npm install
npm run package      # → sema-codebase-chat-<version>.vsix (runs the esbuild bundle first)

Then install the generated .vsix as in step 3.

Develop

npm install
npm run bundle       # esbuild → out/extension.js (bundles the SDKs)

Press F5 in VS Code (with this folder open) to launch an Extension Development Host with the extension loaded. npm run compile typechecks; npm run watch rebuilds on save.

Architecture

VS Code panels  ──CLI --json──►  sema (search / get / reuse / status)  ──►  index
   │                                                                     (ChromaDB + SBERT)
   ├─ chat (local)  ──►  Claude Code / Codex CLI  ──stream──►  panel   (reads/edits repo)
   └─ chat (API)  ──context──►  Anthropic / OpenAI SDK          ──stream──►  panel

Providers run in the Node extension host, so API keys never reach webview/page context.