:robot: AI-generated code notice

Every line of code in this repository was written by Claude (Anthropic's coding agent). The human author's contribution is limited to:

Specifying the desired behavior in natural language.

Verifying the resulting extension behaves correctly inside VS Code (Insiders) by exercising it on real C/C++ files.

No part of the source has been hand-edited or hand-reviewed line-by-line. Treat the code accordingly when auditing for security, correctness, or upstream contribution.

A tiny VS Code extension that hooks the clangd language client and drops every LSP request and notification for files that live outside any open workspace folder. Open a stray .cpp from /tmp and clangd will not see it at all — no indexing, no completion, no diagnostics, no compile_commands.json churn for files you never asked it to look at.

How it works

The official clangd extension exposes a small typed API (@clangd/vscode-clangd) that returns its BaseLanguageClient instance. This extension:

Activates after llvm-vs-code-extensions.vscode-clangd (via extensionDependencies).
Reads api.languageClient.clientOptions.middleware and merges in a filter that short-circuits notifications (didOpen, didChange, didSave, didClose, willSave, willSaveWaitUntil) and request providers (hover, definition, references, completion, code action, formatting, rename, semantic tokens, inlay hints, call/type hierarchy, …) when vscode.workspace.getWorkspaceFolder(uri) returns undefined.
Tracks BaseLanguageClient.onDidChangeState so that clangd.restart and crashes re-attach the middleware to the freshly-spawned client.

No clangd internals are patched; only the public middleware surface is used.

User-facing notifications

Four independent, opt-in channels surface "this file is not indexed":

Setting	Default	Effect
`clangd-filter-files.notify.statusBar`	`true`	A warning-tinted `⊘ clangd: not indexed` item appears on the right side of the status bar while the active editor is a non-workspace C/C++ file.
`clangd-filter-files.notify.toast`	`false`	One-shot `showWarningMessage` per file URI on `onDidOpenTextDocument`.
`clangd-filter-files.notify.diagnostic`	`false`	An `Information` diagnostic is emitted over line 1, visible as a squiggle and in the Problems panel.
`clangd-filter-files.notify.banner`	`false`	An inline "⚠ Outside workspace — clangd is not indexing this file" decoration trailing the topmost visible line. The banner re-anchors as you scroll, and offsets itself below the `editor.stickyScroll` panel so it isn't hidden behind sticky headers. Hover the marker for an Add containing folder to workspace link.

Other settings

clangd-filter-files.allowedSchemes (default ["file"]) — URI schemes that participate in the workspace check. Schemes outside this list are passed through unchanged (so e.g. untitled: or vscode-vfs: documents still reach clangd if you want).
clangd-filter-files.log (default false) — log every drop / banner re-anchor / restart-reattach to the clangd Filter Files output channel. Useful for diagnosing why a particular file does or does not get filtered.
clangd-filter-files.notify.bannerExtraLineOffset (default 0) — additional lines added on top of the automatic sticky-scroll offset. Bump this if the auto offset still leaves the banner too close to the sticky panel for your taste.

Commands

clangd Filter Files: Reattach Middleware — manually re-install the filter on the current language client (only needed if you've automated something unusual; the state-change watcher normally handles restarts).
clangd Filter Files: Add Containing Folder to Workspace — adds the active file's parent directory to the workspace folders, so clangd starts indexing it. Available from the palette, and from the banner's hover link.

Building

npm install
npm run typecheck   # tsc -noEmit
npm run build       # esbuild bundle into out/extension.js
npx @vscode/vsce package --skip-license --allow-missing-repository \
    --out vscode-clangd-filter-files.vsix

F5 from the project folder launches an Extension Development Host with the extension loaded.