Replaces the built-in VS Code Welcome tab with a Claude Code session on startup.

On each window start it:

Sets workbench.startupEditor to none (so the Welcome tab stops opening) — gated by claudeStartup.replaceWelcome. The first time this happens you'll get a one-time notification (it's a global VS Code setting, so it's worth flagging visibly, not just logging).
Invokes a command from the installed Claude Code extension (anthropic.claude-code) to open a session.

Settings

Setting	Default	Meaning
`claudeStartup.mode`	`primaryEditor`	`primaryEditor` → Open in Primary Editor, `recent` → Open (last session), `new` → New Conversation.
`claudeStartup.replaceWelcome`	`true`	Set `workbench.startupEditor` to `none`.
`claudeStartup.autoLaunch`	`true`	Launch automatically on window start. Disable to only use the palette command.
`claudeStartup.skipIfSessionOpen`	`true`	On startup, don't open a session if one is already open in the window. The manual command always opens regardless.

Manual command

Claude Startup: Launch Session (claudeStartup.launch) — fires the same launch on demand.

Build

npm install
npm run compile
npx @vscode/vsce package --allow-missing-repository
code-insiders --install-extension claude-code-startup-0.0.1.vsix

Requires the anthropic.claude-code extension (declared as an extensionDependency).

How it works (for anyone continuing this project)

Everything lives in one file: src/extension.ts. No build system beyond tsc, no framework, no external runtime dependencies — just the vscode API types. That's deliberate, so the whole extension can be read top to bottom in a few minutes:

activate() — VS Code calls this on startup. It registers the manual command, kicks off the one-time Welcome-tab suppression, and (if autoLaunch is on) starts a launch.
launch() / runLaunch() — launch() is just a lock (launchInFlight) wrapped around runLaunch(), so the auto-launch path and a manually-triggered "Retry" can never run at the same time and open two sessions.
waitForAnyCommand() — the Claude Code extension registers its commands asynchronously, so this polls vscode.commands.getCommands() a few times (with a short sleep between attempts) until one of our candidate command IDs shows up, or gives up.
FALLBACKS — per-mode list of command IDs to try, most-specific first. If your preferred mode's command isn't available, the next one in its list is tried instead.
isClaudeSessionOpen() — scans the window's tabs for a Claude Code webview so the startup path can skip reopening when a session is already there. Matches any webview whose viewType mentions "claude" (VS Code prefixes these), so it survives the Claude extension renaming its panels.
ensureWelcomeSuppressed() — reads/writes the global workbench.startupEditor setting exactly once (skips if already "none"), and tells the user about it with a dismissible notification.

Notes

Reloading a window re-fires the launch (a reload is a fresh activation). This is intentional — reload reopens your session.
If the Claude Code extension's commands never appear (not installed / logged out), a warning with a Retry button is shown instead of failing silently. Logs go to the Claude Startup output channel.
The commands this extension calls (claude-vscode.primaryEditor.open, claude-vscode.editor.openLast, claude-vscode.newConversation) belong to the separate Anthropic Claude Code extension, not this one. If a future version of that extension renames or removes them, update MODE_COMMAND / FALLBACKS in src/extension.ts — check the installed extension's package.json contributes.commands list for current IDs.

Contributing

Issues and PRs welcome. This is a small, single-purpose extension — keep changes focused and prefer editing src/extension.ts directly over adding new files unless a change genuinely needs one (see file-organization guidance: many small focused files over few large ones, but this extension is intentionally small enough to stay as one).