Bug: extract links --source fs creates 0 links due to slug normalization mismatch

[richardiitse]

Bug Description

When running gbrain extract links --source fs, the command reports "Created 0 links" despite finding candidate links in the filesystem.

Root Cause

In src/commands/extract.ts, the extractLinksFromDir function builds slugs by stripping the .md extension without normalizing case:

// src/commands/extract.ts ~line 200
const allSlugs = files.map(f => f.relPath.replace('.md', ''));

However, in src/core/sync.ts, slugs are normalized using slugifySegment which applies toLowerCase():

// src/core/sync.ts ~line 211
function slugifySegment(segment: string): string {
  return segment.toLowerCase().replace(/[^a-z0-9]+/g, '');
}

When addLinksBatch performs its JOIN on slug + source_id, the case mismatch causes all links to silently fail insertion:

• Extract provides: synthesis/Synthesis
• Sync normalizes to: synthesis/synthesis
• No match → 0 links created

Reproduction

# Register a source
gbrain sources add wiki --path /path/to/wiki

# Extract links — reports 0 created despite finding candidates
gbrain extract links --source fs --dir /path/to/wiki
# Output: "N candidate links found, 0 created"

Expected Behavior

All links that pass validation should be inserted into the database.

Fix

Replace the raw .replace('.md', '') slug construction in extractLinksFromDir with the existing pathToSlug normalization from sync.ts.

Environment

• OS: macOS (case-insensitive filesystem, but slug JOIN is case-sensitive)
• gbrain version: 0.24.0

[garrytan]

Closing — fixed in master via the v0.30.3 fix-wave (PR #776, merged at ff53a4c9); the canonical fix for this is #736 (extract links --source fs slug normalization).

Thanks for the report — please re-test on the latest release and reopen if anything still reproduces.