Investigating mdsmith bundling in VS Code extension

editors/vscode/README.md

@@ -9,12 +9,21 @@ runs `mdsmith fix` on the whole buffer.
 
 ## Prerequisites
 
-- The `mdsmith` binary on `$PATH`, or a path you supply via
-  the `mdsmith.path` setting. Install with
-  `go install github.com/jeduden/mdsmith/cmd/mdsmith@latest`
-  or download from the
-  [releases page](https://github.com/jeduden/mdsmith/releases).
 - VS Code 1.85 or later.
+- **The `mdsmith` binary** — the extension bundles pre-built binaries
+  for all platforms (Linux, macOS, Windows) from npm. The build step
+  copies platform binaries from the `@mdsmith/*` npm packages into
+  `dist/bin/`, so they ship in the .vsix and work on all platforms
+  from a single install. No separate binary install is required in
+  most cases.
+
+  If the bundled binary is unavailable or you prefer a custom build,
+  you can install `mdsmith` manually:
+  - `npm install -g @mdsmith/cli`
+  - `go install github.com/jeduden/mdsmith/cmd/mdsmith@latest`
+  - Download from the
+    [releases page](https://github.com/jeduden/mdsmith/releases)
+  - Then configure `mdsmith.path` to point to the binary.
 
 ## Install
 
@@ -24,13 +33,13 @@ code --install-extension mdsmith-<version>.vsix
 
 ## Settings
 
-| Setting                | Default     | Purpose                                                                                                                                                                                                  |
-|------------------------|-------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
-| `mdsmith.path`         | `"mdsmith"` | Binary path; resolved against the extension-host PATH (use an absolute path if `which mdsmith` works in your terminal but the extension reports `spawn ENOENT` — `~/.bashrc`/`~/.zshrc` are not sourced) |
-| `mdsmith.config`       | `""`        | Override `-c` config path                                                                                                                                                                                |
-| `mdsmith.run`          | `"onSave"`  | When to lint: `onType`, `onSave`, or `off`                                                                                                                                                               |
-| `mdsmith.fixOnSave`    | `false`     | Wires `source.fixAll.mdsmith` on save                                                                                                                                                                    |
-| `mdsmith.trace.server` | `"off"`     | LSP trace verbosity                                                                                                                                                                                      |
+| Setting                | Default     | Purpose                                                                                                                                                                 |
+|------------------------|-------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| `mdsmith.path`         | `"mdsmith"` | Binary path; defaults to bundled binary in dist/bin/. Falls back to PATH resolution if bundled binary unavailable. Set absolute path if needed (e.g. `/go/bin/mdsmith`) |
+| `mdsmith.config`       | `""`        | Override `-c` config path                                                                                                                                               |
+| `mdsmith.run`          | `"onSave"`  | When to lint: `onType`, `onSave`, or `off`                                                                                                                              |
+| `mdsmith.fixOnSave`    | `false`     | Wires `source.fixAll.mdsmith` on save                                                                                                                                   |
+| `mdsmith.trace.server` | `"off"`     | LSP trace verbosity                                                                                                                                                     |
 
 See the
 [full guide](https://github.com/jeduden/mdsmith/blob/main/docs/guides/editors/vscode.md)

editors/vscode/build.ts

@@ -2,8 +2,10 @@
 // Bundles src/extension.ts into dist/extension.js as a single CJS
 // file consumed by VS Code, marking `vscode` as external because
 // the host supplies it at runtime.
+// Also copies platform binaries from @mdsmith/* packages into dist/bin/
+// so they can be bundled in the .vsix (even with --no-dependencies).
 
-import { copyFileSync, existsSync } from "node:fs";
+import { copyFileSync, existsSync, mkdirSync, readdirSync } from "node:fs";
 import { join } from "node:path";
 
 const args = Bun.argv.slice(2);
@@ -22,6 +24,47 @@ if (existsSync(repoLicense)) {
   copyFileSync(repoLicense, stagedLicense);
 }
 
+// Copy platform binaries from @mdsmith/* packages into dist/bin/
+// so they ship in the .vsix even with vsce package --no-dependencies.
+// The npm packages install as optional dependencies; when present,
+// bundle them. When absent (offline install, proxy), the extension
+// falls back to PATH resolution.
+function copyPlatformBinaries() {
+  const distBin = join(import.meta.dir, "dist", "bin");
+  mkdirSync(distBin, { recursive: true });
+
+  // Platform packages that @mdsmith/cli declares as optionalDependencies
+  const platforms = [
+    { pkg: "@mdsmith/linux-x64", binary: "mdsmith" },
+    { pkg: "@mdsmith/linux-arm64", binary: "mdsmith" },
+    { pkg: "@mdsmith/darwin-x64", binary: "mdsmith" },
+    { pkg: "@mdsmith/darwin-arm64", binary: "mdsmith" },
+    { pkg: "@mdsmith/win32-x64", binary: "mdsmith.exe" },
+  ];
+
+  let copied = 0;
+  for (const { pkg, binary } of platforms) {
+    const srcBin = join(import.meta.dir, "node_modules", pkg, "bin", binary);
+    if (existsSync(srcBin)) {
+      const destBin = join(distBin, `${pkg.replace("@mdsmith/", "")}-${binary}`);
+      copyFileSync(srcBin, destBin);
+      copied++;
+    }
+  }
+
+  if (copied > 0) {
+    console.log(`copied ${copied} platform binary/binaries → dist/bin/`);
+  } else {
+    console.warn(
+      "warning: no platform binaries found in node_modules/@mdsmith/; " +
+      "extension will fall back to PATH resolution. Run `npm install` " +
+      "to bundle binaries."
+    );
+  }
+}
+
+copyPlatformBinaries();
+
 const config: Parameters<typeof Bun.build>[0] = {
   entrypoints: ["src/extension.ts"],
   outdir: "dist",

editors/vscode/package.json

@@ -47,7 +47,7 @@
         "mdsmith.path": {
           "type": "string",
           "default": "mdsmith",
-          "description": "Path to the mdsmith binary. A bare name is resolved against VS Code's extension-host PATH, which is the container/login-shell environment — interactive-only files like ~/.bashrc and ~/.zshrc are NOT sourced. If `which mdsmith` works in a terminal but the extension reports `spawn ENOENT`, set this to an absolute path (e.g. /go/bin/mdsmith) or symlink the binary into /usr/local/bin."
+          "description": "Path to the mdsmith binary. Defaults to the bundled binary in dist/bin/ (copied from @mdsmith/* npm packages during build). Works on Linux, macOS, and Windows from a single .vsix. If the bundled binary is unavailable, falls back to resolving 'mdsmith' against PATH. Set to an absolute path if you installed mdsmith elsewhere (e.g. /go/bin/mdsmith)."
         },
         "mdsmith.config": {
           "type": "string",
@@ -84,6 +84,9 @@
   "dependencies": {
     "vscode-languageclient": "^9.0.1"
   },
+  "optionalDependencies": {
+    "@mdsmith/cli": "0.0.0-dev"
+  },
   "devDependencies": {
     "@types/bun": "^1.1.0",
     "@types/node": "^20.11.0",

editors/vscode/src/binary.test.ts

@@ -0,0 +1,72 @@
+// Unit tests for binary resolution logic.
+// The extension bundles cross-platform mdsmith binaries into dist/bin/
+// during the build step; these tests verify the resolution logic and
+// fallback behavior.
+
+import { describe, expect, mock, test } from "bun:test";
+import { join } from "node:path";
+import { resolveBinary } from "./binary";
+
+describe("resolveBinary", () => {
+  test("returns custom path unchanged when user specifies non-default", () => {
+    const fileExists = mock(() => false);
+    const result = resolveBinary("/custom/path/to/mdsmith", "/ext", "linux", "x64", fileExists);
+    expect(result).toBe("/custom/path/to/mdsmith");
+    // Should not even attempt to check for bundled binary
+    expect(fileExists).not.toHaveBeenCalled();
+  });
+
+  test("returns bundled binary when default path and bundled exists (Linux x64)", () => {
+    const extensionPath = "/ext";
+    const bundledPath = join(extensionPath, "dist", "bin", "linux-x64-mdsmith");
+
+    // Mock: bundled binary exists
+    const fileExists = mock((path) => path === bundledPath);
+
+    const result = resolveBinary("mdsmith", extensionPath, "linux", "x64", fileExists);
+    expect(result).toBe(bundledPath);
+    expect(fileExists).toHaveBeenCalledWith(bundledPath);
+  });
+
+  test("returns bundled binary when default path and bundled exists (macOS arm64)", () => {
+    const extensionPath = "/ext";
+    const bundledPath = join(extensionPath, "dist", "bin", "darwin-arm64-mdsmith");
+
+    // Mock: bundled binary exists
+    const fileExists = mock((path) => path === bundledPath);
+
+    const result = resolveBinary("mdsmith", extensionPath, "darwin", "arm64", fileExists);
+    expect(result).toBe(bundledPath);
+    expect(fileExists).toHaveBeenCalledWith(bundledPath);
+  });
+
+  test("returns bundled binary when default path and bundled exists (Windows x64)", () => {
+    const extensionPath = "/ext";
+    const bundledPath = join(extensionPath, "dist", "bin", "win32-x64-mdsmith.exe");
+
+    // Mock: bundled binary exists
+    const fileExists = mock((path) => path === bundledPath);
+
+    const result = resolveBinary("mdsmith", extensionPath, "win32", "x64", fileExists);
+    expect(result).toBe(bundledPath);
+    expect(fileExists).toHaveBeenCalledWith(bundledPath);
+  });
+
+  test("falls back to default path when bundled binary does not exist", () => {
+    // Mock: no bundled binary
+    const fileExists = mock(() => false);
+
+    const result = resolveBinary("mdsmith", "/ext", "linux", "x64", fileExists);
+    expect(result).toBe("mdsmith");
+    // Should have checked for bundled binary
+    expect(fileExists).toHaveBeenCalled();
+  });
+
+  test("returns custom bare name unchanged", () => {
+    const fileExists = mock(() => false);
+    const result = resolveBinary("my-mdsmith-fork", "/ext", "linux", "x64", fileExists);
+    expect(result).toBe("my-mdsmith-fork");
+    // Should not check for bundled binary when not the default
+    expect(fileExists).not.toHaveBeenCalled();
+  });
+});

editors/vscode/src/binary.ts

@@ -0,0 +1,65 @@
+// Binary resolution logic for the mdsmith extension.
+// The extension bundles cross-platform mdsmith binaries from npm packages
+// into dist/bin/ during the build step. This module resolves the correct
+// platform binary when the user leaves the default "mdsmith" path, falling
+// back to PATH if bundling failed or binaries are unavailable.
+
+import { existsSync } from "node:fs";
+import { join } from "node:path";
+
+// resolveBinary returns the path to the mdsmith binary. When the
+// configured path is the bare string "mdsmith", it first checks for
+// bundled binaries in dist/bin/ (copied there by build.ts from the
+// @mdsmith/* npm packages). Platform-specific binaries are named like
+// "linux-x64-mdsmith", "win32-x64-mdsmith.exe", etc. If the bundled
+// binary exists, return its absolute path. Otherwise return the
+// configured path unchanged so the LanguageClient resolves it against
+// PATH (fallback for dev builds or when optional deps failed to install).
+//
+// Cross-platform bundling: The build script copies binaries from ALL
+// @mdsmith/* platform packages (linux-x64, darwin-arm64, win32-x64, etc.)
+// into dist/bin/. This works even with `vsce package --no-dependencies`
+// because dist/ is included in the .vsix. At runtime, this function
+// selects the binary matching the user's OS+arch.
+//
+// The extensionPath should be the vscode.ExtensionContext.extensionPath
+// (the directory containing package.json and dist/).
+//
+// The optional platform, arch, and fileExists parameters are for testing;
+// in production they default to process.platform, process.arch, and fs.existsSync.
+export function resolveBinary(
+  configuredPath: string,
+  extensionPath: string,
+  platform: string = process.platform,
+  arch: string = process.arch,
+  fileExists: (path: string) => boolean = existsSync
+): string {
+  // If the user specified a custom path (not the bare "mdsmith"),
+  // honor it exactly — they know what they want.
+  if (configuredPath !== "mdsmith") {
+    return configuredPath;
+  }
+
+  // The user left the default "mdsmith". Check for bundled binaries
+  // in dist/bin/. The build script copies them there with names like
+  // "linux-x64-mdsmith", "win32-x64-mdsmith.exe".
+
+  // Map Node's process.platform and process.arch to our package names
+  const platformArch = `${platform}-${arch}`;
+  const binaryName = platform === "win32" ? "mdsmith.exe" : "mdsmith";
+  const bundledBinary = join(
+    extensionPath,
+    "dist",
+    "bin",
+    `${platformArch}-${binaryName}`
+  );
+
+  if (fileExists(bundledBinary)) {
+    return bundledBinary;
+  }
+
+  // The bundled binary does not exist (build step didn't run, or
+  // optional dependencies weren't installed). Fall back to the bare
+  // "mdsmith" string so the LanguageClient resolves it against PATH.
+  return configuredPath;
+}

editors/vscode/src/extension.ts

@@ -18,6 +18,7 @@ import {
   collectFixAllEdits,
   startupErrorMessage
 } from "./wiring";
+import { resolveBinary } from "./binary";
 
 let client: LanguageClient | undefined;
 // Track the .mdsmith.yml file watcher across the activate /
@@ -74,7 +75,8 @@ export async function activate(context: vscode.ExtensionContext): Promise<void>
 // must remain usable so the user can retry.
 async function startServer(context: vscode.ExtensionContext): Promise<void> {
   const cfg = vscode.workspace.getConfiguration("mdsmith");
-  const binary = cfg.get<string>("path", "mdsmith");
+  const configuredPath = cfg.get<string>("path", "mdsmith");
+  const binary = resolveBinary(configuredPath, context.extensionPath);
   const workspaceRoot = vscode.workspace.workspaceFolders?.[0]?.uri.fsPath;
 
   const serverOptions: ServerOptions = buildServerOptions(