Module sites 

Named emit helpers for the five M1.6 hot phases.

Each helper builds a fully-populated super::TraceEvent for a specific phase and forwards it to super::emit. Callers who want finer control can construct events directly with super::TraceEvent::new and the builders.

Why this module exists

Engine code that wants to emit a trace event should call one of these helpers rather than re-typing the Phase/Reason literal tags. That keeps the call sites short, makes refactors localised, and gives reviewers a single place to inspect the shape of trace events for each phase.

All helpers are zero-cost when no sink is installed (one thread-local read + an Option::is_some branch).

Wiring status (M1 v1)

These helpers are public API and exercised by the integration test in tests/trace_sites.rs. Production wiring of these calls into the XFA layout/data-binding code paths is staged behind a follow-up and is intentionally not part of M1.6 because:

• The five hot phases live across xfa-layout-engine::layout, xfa-layout-engine::form, and pdf-xfa::dynamic. Each call site needs case-specific input/decision text that v1 does not yet curate.
• Wiring during M1 risks subtle regressions in layout/page-count gates, which would make the determinism gate noisy precisely as we are trying to land it.

Therefore M1.6 ships:

• The taxonomy (M1.5).
• These five typed emit helpers (this module) — exercised end-to-end.
• Documentation in M1_RESULT.md marking the production wiring as PARTIAL with a clear hand-off pointer.

Functions

bind

Emit a bind phase event.

fallback

Emit a fallback phase event.

occur

Emit an occur phase event.

paginate

Emit a paginate phase event.

presence

Emit a presence phase event.

suppress

Emit a suppress phase event.