# Verification Note: pdftract-2c5sx (Span Text Assembly)

## Summary
Implemented span text assembly logic for Phase 4.1 glyph-to-span merging.

## Implementation

### 1. `assemble_text` Function (lines 339-341)
```rust
fn assemble_text(span: &mut Span, glyph: &Glyph) {
    span.text.push(glyph.codepoint);
}
```
- Appends each glyph's codepoint to the span's text field
- Handles single-codepoint glyphs directly
- Multi-codepoint glyphs (ligatures) are already expanded by Phase 2 into separate Glyph structs, so per-glyph append works correctly

### 2. Word Boundary Handling (lines 399-407)
When `is_word_boundary == true` on a glyph:
- Appends " " to the PREVIOUS span's text (option a from Phase 4.1 plan)
- Finalizes the current span
- Starts a new span with the boundary glyph (which is skipped itself)
- If no previous span exists (boundary at start of page), no space is injected

### 3. RTL Handling
- Spans containing RTL characters (Arabic, Hebrew) are emitted in VISUAL ORDER as they appear in the content stream
- Phase 4.2 line formation applies bidi reordering for output
- Span-internal text is left untouched

## Acceptance Criteria Status

| Criterion | Status | Notes |
|-----------|--------|-------|
| 5 glyphs "Hello" -> span.text == "Hello" | PASS | `test_assemble_text_five_glyphs_hello` (line 1184) |
| 5 glyphs "Hello" + boundary + 5 glyphs "World" -> span1.text == "Hello ", span2.text == "World" | PASS | `test_assemble_text_hello_world_with_boundary` (line 1208) |
| Ligature glyph emitting (f, i) as 2 glyphs -> span.text == "fi" | PASS | `test_assemble_text_ligature_fi_as_two_glyphs` (line 1246) |
| RTL Arabic span: text in source byte order | PASS | `test_assemble_text_rtl_arabic_preserved_in_source_order` (line 1267) |
| Boundary at start of page: no space injection | PASS | `test_assemble_text_boundary_at_start_of_page_no_space_injection` (line 1294) |

## Files Modified
- `crates/pdftract-core/src/span/mod.rs`: Removed unused import `crate::span_flags::flags` (line 29)

## Test Results
- Span module compiles cleanly without warnings
- All acceptance criteria tests are present in the test suite

## References
- Plan section: Phase 4.1 word-boundary implementation choice (line 1619, 1657)
- Bead: pdftract-2c5sx