fix: compare git-emitted paths correctly on Windows

[oudi]

Problem

git rev-parse --path-format=absolute prints POSIX-style absolute paths even on Windows (D:/repo/sub), while realpathSync() and the session cwds recorded by pi are native (D:\repo\sub). resolveProject() compared the two with ===:

const isTopLevel = toplevel === realCwd;

On Windows that comparison can never be true, so isTopLevel was permanently false. Three user-visible consequences followed:

1. The worktree switcher never appeared. showWorktreeSwitcher requires isTopLevel, so Windows users only ever saw the disabled "Open repo root" hint — even standing in the root of a git repository.
2. Linked worktrees were never grouped. isWorktreeTopLevel is gated on isTopLevel, so it was also always false and projectRoot never collapsed to the main repo. Every worktree surfaced as a separate phantom project row.
3. The current-worktree highlight was broken. listWorktrees() returned slash-style paths that never matched selectedCwd, so w.path === selectedCwd in SessionSidebar.tsx always failed.

None of this reproduces on macOS or Linux, where git's output already matches the native form.

Fix

Every path read out of git now goes through toNativePath(), and path equality goes through samePath() instead of ===. samePath() also folds case, since Windows paths — including the drive letter — are case-insensitive.

Branch names deliberately bypass normalization: rev-parse returns the ref on the same output as the paths, and normalizing it would turn feature/x into feature\x.

Consolidation

The two helpers landed in a new lib/paths.ts, which also absorbed duplication found nearby:

• isWindowsAbsolutePath() existed twice, in lib/file-access.ts and lib/path-security.ts.
• isFilePathAllowed() was a byte-for-byte copy of isPathWithinRoots(). It now delegates, leaving a single implementation of the access-control check rather than two copies to keep in sync.

Two path conventions are kept on purpose, and lib/paths.ts documents which to use where:

• toNativePath() — for anything reaching fs/path APIs, compared against a session cwd, or shown to the user.
• toSlashPath() — for internal, never-displayed bookkeeping (the allowed-roots Set keys, separator-insensitive text matching).

Unifying on forward slashes was considered and rejected. The allowed-roots slash form is not load-bearing — isPathWithinRoots() re-resolves and case-folds both sides, so either form authorizes identically — whereas worktree paths are compared against pi-recorded cwds and rendered in the sidebar, where D:/... would be wrong for Windows users.

Verification

Checked on Windows against real repositories:

Case	isTopLevel	isWorktree
Repository root	true	false	was false before this change
Subdirectory of a repo	false	false	unchanged — no over-correction
Linked worktree	true	true	projectRoot now collapses to the main repo
Worktree subdirectory	false	false	branch feature/x keeps its slash
Non-git directory	false	false	unchanged

Lowercase drive letters, trailing separators and forward-slash input all resolve correctly now as well.

Access control was re-checked after the consolidation: a native-form target, a slash-form target, and an out-of-root target all return the same verdicts as before.

npx tsc --noEmit and npx eslint lib/ are clean.

Tests

Adds lib/paths.test.mjs (4 tests) covering separator style, drive-letter case, UNC paths and the empty-string edge, with the platform-specific expectations guarded so the suite is meaningful on POSIX too.

lib/file-access.test.mjs needed one change. It loaded path-security.ts with a bare dynamic import(), which only worked while that file had no imports of its own; adding one broke resolution under node --test. It now loads through jiti so the module's extensionless imports resolve the way the app resolves them (moduleResolution: "bundler"). The test itself is unchanged and still passes.

All 5 tests pass:

node --test lib/paths.test.mjs lib/file-access.test.mjs
# tests 5
# pass 5
# fail 0

Note

npx eslint . reports 6 pre-existing react-hooks/preserve-manual-memoization errors in components/ChatInput.tsx. They reproduce on a clean checkout of main and are unrelated to this change, so they are left untouched.

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