[SeanLiu326]

What

isPluginWorkspace never matched on Windows, so the bundled pi-desktop/plugin-development skill was never offered for a workspace a plugin was already loaded from.

Root cause

apps/desktop/electron/main/builtin-skills.ts built its containment prefix with a literal / and compared spellings verbatim:

const prefix = workspacePath.endsWith("/") ? workspacePath : `${workspacePath}/`;
return pluginPaths.some((path) => path === workspacePath || path.startsWith(prefix));

The two inputs arrive from different worlds:

• pluginPaths — plugins.listLoaded().map((loaded) => loaded.path), stored verbatim from the folder the user picked (dialog.showOpenDialog → native backslashes on Windows).
• workspacePath — the host's session.get/workspace.get answer, which can persist a forward-slash spelling or the //?/X:/… long-path variant (electron/main/path-utils.ts exists precisely because both spellings occur).

Even with both sides natively backslashed, the /-suffixed prefix (C:\dev\repo/) never matched C:\dev\repo\plugins\my-plugin. On macOS/Linux both sides are forward-slashed, so only Windows broke. The manifest.json-at-root probe still rescued the single-plugin-at-root layout; a monorepo with plugins in a subdirectory got nothing. Both callers are affected: session launch (runtime/session-launch.ts:546) and the composer command build (ipc/composer-ipc.ts:63).

Fix

Containment now folds both sides before comparing — separators unified to /, the Windows verbatim prefix stripped in either spelling, trailing separators dropped, and case folded everywhere but Linux (the same platform split the worktree ref folding uses). The sibling-prefix boundary is preserved: repo-x never counts as inside repo. The comparison lives in a new dependency-free module (plugin-workspace-contains.ts) so its behavior is tested directly, following the plugin-session-push-gate.ts precedent.

Tests

apps/desktop/test/plugin-workspace-contains.test.mjs — separator/long-prefix/case unification, the workspace-root case, and the sibling-prefix boundary on both drive and POSIX shapes. 2/2 pass locally (Windows box, which is the broken platform); plugin-skills.test.mjs stays green.

[vastsa]

The Windows separator defect is real, and I tested the new helper directly. It introduces a regression for a valid POSIX filesystem-root workspace: pluginWorkspaceContains('/', '/tmp/plugins/example') returns false because trimming trailing slashes turns / into the empty string; the existing prefix check returns true. Please preserve filesystem roots during normalization and add coverage for / (plus drive-root containment) before landing. Keep the sibling boundary test. This is a behavioral regression, independent of CI.

[SeanLiu326]

Good catch — fixed in 1739a9c30 (branch now merges current main, head f487f436e).

The regression: fold trimmed trailing separators before deciding anything, so a bare root folded to "", hit the empty-workspace guard, and answered false. The prefix check it replaced treated / as "/" and matched every absolute path, so this was strictly narrower than the old behavior.

The fix: a path made only of separators is now recognized as the filesystem root and preserved through the fold (/, /// → /), and the POSIX root compares plugin.startsWith("/") directly instead of the ${workspace}/ spelling that would become //. Drive roots need no special case — C:/ folds to c: and the ordinary c:/… prefix test keeps working, including the //?/C:/ verbatim spelling.

Coverage added (kept the sibling boundary test untouched):

• pluginWorkspaceContains("/", "/tmp/plugins/example") → true, ("/", "/") → true, ("///", …) → true, ("/", "tmp/plugins/example") → false
• drive roots: ("C:/", "C:/dev/repo/plugins/p"), ("C:\", "C:\…"), ("C:/", "C:"), verbatim //?/C:/, and ("C:/", "D:/…") → false

test/plugin-workspace-contains.test.mjs + test/plugin-skills.test.mjs — 18/18 pass (cases use consistent casing so they hold on Linux too), tsc --noEmit clean.

[vastsa]

The revised root normalization addresses the regression from the previous review. Independently ran all 18 plugin-workspace/plugin-skill tests and Desktop typecheck, and bundled/imported the production isPluginWorkspace entry point to verify Windows nested-plugin detection, POSIX / workspaces and sibling rejection. All pass. The original Windows prefix check fails the nested-backslash case; the revised implementation fixes it while preserving root containment. Refreshing the integration candidate and proceeding to land this focused fix; CI status is not a blocker in this review.