# pdftract-342k4: XFA Detection — Verification Note

## Summary

XFA detection (`detect_xfa`) was **already implemented** in the codebase at the time of bead assignment. No implementation work was required.

## Implementation Status

### Function Location
- **File:** `crates/pdftract-core/src/forms/mod.rs`
- **Lines:** 66-72
- **Export:** Public API in `lib.rs` line 73

### Implementation
```rust
pub fn detect_xfa(acroform: &Option<PdfDict>) -> bool {
    acroform
        .as_ref()
        .and_then(|af| af.get("XFA"))
        .map(|xfa| !matches!(xfa, PdfObject::Null))
        .unwrap_or(false)
}
```

This matches the bead's specification exactly.

## Acceptance Criteria Verification

All acceptance criteria PASS:

| # | Criteria | Test | Status |
|---|----------|------|--------|
| 1 | PDF with AcroForm /XFA stream → true | `test_detect_xfa_xfa_stream` | ✅ PASS |
| 2 | PDF with AcroForm /XFA [name, stream, ...] (packet form) → true | `test_detect_xfa_xfa_array_packet_form` | ✅ PASS |
| 3 | PDF with AcroForm but no /XFA key → false | `test_detect_xfa_no_xfa_key` | ✅ PASS |
| 4 | PDF with AcroForm /XFA null → false | `test_detect_xfa_xfa_null` | ✅ PASS |
| 5 | PDF with no AcroForm → false | `test_detect_xfa_no_acroform` | ✅ PASS |

**Additional coverage:** `test_detect_xfa_xfa_ref` covers indirect reference handling (also returns true).

## Test Run

```bash
$ cargo nextest run -p pdftract-core --lib detect_xfa
Starting 6 tests across 1 binary (2539 tests skipped)
    PASS [   0.004s] (1/6) pdftract-core forms::tests::test_detect_xfa_no_acroform
    PASS [   0.005s] (2/6) pdftract-core forms::tests::test_detect_xfa_no_xfa_key
    PASS [   0.005s] (3/6) pdftract-core forms::tests::test_detect_xfa_xfa_stream
    PASS [   0.005s] (4/6) pdftract-core forms::tests::test_detect_xfa_xfa_ref
    PASS [   0.006s] (5/6) pdftract-core forms::tests::test_detect_xfa_xfa_null
    PASS [   0.006s] (6/6) pdftract-core forms::tests::test_detect_xfa_xfa_array_packet_form
────────────
 Summary [   0.008s] 6 tests run: 6 passed, 2539 skipped
```

## Files

- Implementation: `crates/pdftract-core/src/forms/mod.rs:66-72`
- Tests: `crates/pdftract-core/src/forms/mod.rs:1437-1510`
- Export: `crates/pdftract-core/src/lib.rs:73`

## Conclusion

**Bead complete.** The XFA detection function was already implemented with full test coverage. No code changes were required.