bug(vim): resolveVimRuntime never matches Windows path separators

[dnieblesdev]

Before submitting

• I searched open and closed issues and did not find a report of this problem.
• I reviewed this report and removed credentials, tokens, private paths, hostnames, and other sensitive data.

Problem

On Windows, resolveVimRuntime() in extensions/gentle-shell.ts can never identify the Pi runtime, because its candidate tests compare a native Windows path against POSIX-style suffixes:

• extensions/gentle-shell.ts:47 — if (cli.endsWith("/dist/bundle/cli.js"))
• extensions/gentle-shell.ts:68 — if (cli.endsWith("/dist/bundle/cli.js")) candidates.push(resolve(dirname(cli), "../.."))
• extensions/gentle-shell.ts:73 — if (localIndex.endsWith("/dist/index.js")) candidates.push(resolve(dirname(localIndex), ".."))

On Windows those paths are backslash-separated (...\node_modules\@earendil-works\pi-coding-agent\dist\index.js), so every check is false, candidates stays empty, and the function returns undefined. The verified runtime path is therefore unreachable on Windows: vimAdapter() falls back to this.deps.tuiVersion?.() ?? "unknown" with the locally imported Editor and an undefined verifiedVersion, and the identity guard in lib/vim-editor-adapter.ts (value instanceof editorClass) can then reject the host editor, which disables Vim through the existing "Gentle Vim unsupported by this Pi editor layout/version" path.

This is production code, and it is separate from #1430: #1430 reports two Editor constructors under a fresh npm install on Linux (fixtures). Here resolution never reaches the constructor comparison at all, because the separators never match.

Suggested fix: make all three sites separator-agnostic, for example endsWith(join("dist", "bundle", "cli.js")) or by comparing against resolve(root, "dist", "index.js") instead of a suffix.

Steps to reproduce

1. On Windows, check out 54568116 (gentle-pi 3.7.0) and install dependencies with pnpm install (Node 24, pnpm 11.1.1).
2. Run node --experimental-strip-types --test tests/vim-editor-adapter.test.ts. Three tests fail, all of them on resolveVimRuntime() returning undefined instead of the installed pair.
3. The separator mismatch alone reproduces it, without the test suite:

import { fileURLToPath } from "node:url";
console.log(fileURLToPath(import.meta.resolve("@earendil-works/pi-coding-agent")));
// <checkout>\node_modules\@earendil-works\pi-coding-agent\dist\index.js
console.log(fileURLToPath(import.meta.resolve("@earendil-works/pi-coding-agent")).endsWith("/dist/index.js"));
// false — so no candidate root is ever pushed on Windows

Expected and actual behavior

Expected: resolveVimRuntime() resolves the installed Pi pair on Windows exactly as it does on macOS/Linux, reporting { version: "0.87.1", editorClass: <host editor class> }.

Actual: it returns undefined on Windows, in both the CLI-entry candidate branch and the local-index candidate branch, so the runtime identity is never verified there.

gentle-pi version

3.7.0 (54568116)

Pi version

0.87.1

Operating system

Windows

Relevant logs or error output (optional)

failing tests (tests/vim-editor-adapter.test.ts):
- PATH bundled virtual host is admitted only through its exact bundled class and version
- runtime identity resolves only the matching installed coding-agent/TUI pair
- resolveVimRuntime's default entry resolves the declared local 0.87.1 install without any PATH Pi

✖ resolveVimRuntime's default entry resolves the declared local 0.87.1 install without any PATH Pi
  AssertionError [ERR_ASSERTION]: Expected values to be strictly deep-equal:
  + actual - expected
  + undefined
  - { editorClass: [class Editor], version: '0.87.1' }

# separator probe on the same checkout
import.meta.resolve(agent): <checkout>\node_modules\@earendil-works\pi-coding-agent\dist\index.js
endsWith("/dist/index.js"): false
candidate roots: []
resolveVimRuntime("/nonexistent/cli.js"): undefined