@W-23618508 fix VS Code extension blocking others on empty workspace - #598

Summary

Fixes W-23618508: the B2C Commerce VS Code extension was blocking other extensions when opened in an empty (no-folder) or non-B2C workspace. Clicking a B2C DX activity-bar icon in an empty window would spin forever, and other extensions (e.g. Claude Code) would also show a loading badge with an empty, un-activated panel.

Root cause

VS Code runs all extensions in a single shared extension-host process, so synchronous CPU work in one extension's activation stalls the event loop and makes every other extension appear stuck "activating" (the spinner + empty panels in the repro).

The extension can be activated in an empty window by several events — clicking a B2C DX view icon (onView:*), or opening any JS/TS file (the extension contributes a TypeScript server plugin, which VS Code loads for all JS/TS files). Whatever the trigger, activate() → activateInner() then ran heavy synchronous, unbounded filesystem work:

1. detectWorkingDirectory() fell back to process.cwd() when there were no workspace folders — the extension host's arbitrary cwd, often the user's home directory.
2. Eager activation work then ran unbounded globSync('**/.project') walks on the shared extension-host thread (via registerScriptTypes → CartridgeService.getCartridges() → findCartridges(cwd), and updateStorefrontNextContext() → detectWorkspaceType(cwd)).

Scanning the whole home tree synchronously freezes the extension host, blocking every other extension.

Fix (all in packages/b2c-vs-extension)

Do no filesystem discovery without a concrete workspace folder, and never let findCartridges scan out of home/root:

• workspace-discovery.ts: added isUnscannableRoot(dir) (empty / home dir / filesystem root) and findCartridgesSafe(dir, opts) — the single entry point all extension cartridge discovery now uses. It returns [] for unscannable roots (never falls back to process.cwd()) and depth-bounds every scan (WORKSPACE_DISCOVERY_MAX_DEPTH = 5). Mirrors the MCP server's existing registry.ts home/root guard.
• config-provider.ts: detectWorkingDirectory() returns '' (not process.cwd()) when there are no workspace folders; resolveAsync skips resolution/discovery for home/root/missing dirs.
• extension.ts: updateStorefrontNextContext() skips detection for unscannable roots and depth-bounds the scan otherwise.
• Routed all findCartridges call sites through findCartridgesSafe (cartridge-service, code-sync-manager, deploy-command, debugger, jobs-commands, jobs-tree-provider, scaffold-commands, onboardingPanel) so no path can recursively scan out of home.

Manual testing

Reproduce the original report:

1. Install the VSIX and open VS Code → File → New Window (empty window, no folder).
2. Click any B2C DX activity-bar icon (WebDAV Explorer, Sandbox Explorer, etc.).
   • Before: the B2C icon shows a spinner that never resolves; clicking another extension's icon (e.g. Claude Code) also shows a spinner with an empty, un-activated panel — the extension host is blocked.
   • After: the B2C DX views load immediately (empty/welcome state) and other extensions activate normally with no spinner. Output → B2C DX logs No workspace folders open; skipping filesystem discovery.
3. (Also) open your home directory as a folder and confirm the extension does not hang and does no recursive .project scan.
4. (Regression) open a real B2C project (with dw.json and cartridges) and confirm cartridge discovery, code sync, debugger, and Script API IntelliSense still work as before.