bf-1puzp: CMAP skip logic for unmapped glyphs - VERIFICATION

Summary

The CMAP skip logic for unmapped glyphs was already implemented in the codebase. This note verifies the implementation meets all acceptance criteria.

Implementation location

File: /home/coding/pdftract/crates/pdftract-core/src/font/encoding.rs Lines: 196-203 Function: DifferencesOverlay::parse()

// MARKER: CMAP entry creation point - Type1 font encoding differences.
if cursor <= 255 {
    // Skip unmapped glyph names (e.g., .notdef) to prevent them from
    // appearing in text extraction output. These glyphs have no valid
    // Unicode mapping and should emit GLYPH_UNMAPPED diagnostics instead.
    if !crate::font::is_unmapped_glyph_name(&name) {
        overlay.entries.push((cursor as u8, Arc::clone(name)));
    }
}

Supporting infrastructure

File: /home/coding/pdftract/crates/pdftract-core/src/font/unmapped.rs

Defines UNMAPPED_GLYPH_NAMES: LazyLock<HashSet<&'static str>> containing ".notdef"
Provides is_unmapped_glyph_name(name: &str) -> bool helper function
Handles both /name and name formats (strips leading slash)

Acceptance criteria verification

✅ PASS: Generator checks glyph name against unmapped_glyph_names config before CMAP entry creation

Line 200: if !crate::font::is_unmapped_glyph_name(&name)

✅ PASS: Unmapped glyphs are skipped during CMAP generation

Lines 200-203: Unmapped glyphs are not added to overlay.entries

✅ PASS: Code compiles without errors

Verified: cargo check --lib -p pdftract-core completed successfully

✅ PASS: Simple test demonstrating skip behavior

Test: test_differences_overlay_skips_notdef (line 676)
Test: test_differences_overlay_skips_notdef_with_slash (line 696)

Test results

All 24 encoding tests pass:

running 24 tests
test font::encoding::tests::test_differences_overlay_skips_notdef ... ok
test font::encoding::tests::test_differences_overlay_skips_notdef_with_slash ... ok
test result: ok. 24 passed; 0 failed; 0 ignored

Behavior

When a /Differences array contains .notdef or /.notdef:

The glyph name is checked against UNMAPPED_GLYPH_NAMES
If unmapped, the entry is skipped (not added to the overlay)
No error is emitted (clean skip)
Normal glyphs continue to be added

This prevents .notdef from appearing in text extraction output while allowing it to remain valid in the PDF font encoding specification.

Git status

No changes required - implementation was already complete in the codebase.

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