fix(core): strip trailing slash from _sourceFile in navDesignatedIndexFiles

[sinsombat]

Bug

When a folder contains .md files but no index.md, the auto-router promotes the first file to the folder-level URL (e.g. _sourceFile is stored, path is reassigned to basePath). However, clicking that nav link results in a 404.

Root Cause

In auto-router.ts, normalizeInternalHref() adds a trailing slash to linkPath before it is stored as _sourceFile:

_sourceFile = "/SA/feature-discovery/feature-active-reward-edit/"  ← trailing slash

In generator.ts, the Set is populated by stripping the leading slash only:

navDesignatedIndexFiles.add(item._sourceFile.replace(/^\//, ));
// → "SA/feature-discovery/feature-active-reward-edit/"  ← still has trailing slash

But relWithoutExt (the key used in .has()) has no trailing slash:

const relWithoutExt = relativePath.replace(/\.(md|markdown|ejs)$/i, );
// → "SA/feature-discovery/feature-active-reward-edit"  ← no trailing slash

So navDesignatedIndexFiles.has(relWithoutExt) is always false, meaning isNavDesignatedIndex is never set, effectivelyIndex stays false, and the file is output at SA/feature-discovery/feature-active-reward-edit/index.html instead of the intended SA/feature-discovery/index.html.

Result: nav link /SA/feature-discovery has no matching index.html → 404.

Reproduction

docs/
  SA/
    feature-discovery/
      my-page.md        ← no index.md in this folder

Expected: clicking feature-discovery in the sidebar → 200 (content of my-page.md)
Actual: 404 (site/SA/feature-discovery/index.html is never generated)

Fix

Strip the trailing slash when normalising _sourceFile before adding to the Set, making it consistent with relWithoutExt:

// before
navDesignatedIndexFiles.add(item._sourceFile.replace(/^\//, ));

// after
navDesignatedIndexFiles.add(item._sourceFile.replace(/^\//, ).replace(/\/$/, ));

Tested

• Built the fixed binary locally
• Removed index.md workaround from a project folder
• site/SA/feature-discovery/index.html now generated correctly
• Nav link /SA/feature-discovery → HTTP 200 ✓

[mgks]

Implementation verified. The fix correctly handles auto-designated index normalization by stripping the trailing slash to match the internal comparison format. Great catch, merging!