diff --git a/.project/objectives/p3-29-rail1-turn-unification.md b/.project/objectives/p3-29-rail1-turn-unification.md
index 7735957e..41e8a0af 100644
--- a/.project/objectives/p3-29-rail1-turn-unification.md
+++ b/.project/objectives/p3-29-rail1-turn-unification.md
@@ -47,3 +47,28 @@ emits vs `TurnResult`; (2) wire turn_manager → GdTurnProcessor.step behind the
 (3) delete the GDScript orchestration; (4) render-proof on apricot/plum. This is the true
 Rail-1 finish line — bigger than B7 (per-building queues), which becomes moot once the live
 game runs the Rust turn (which has the model the unified turn will use).
+
+## De-risking audit (2026-06-27) — the bulk is event-surfacing, not the call-swap
+
+`GdTurnProcessor::step(GdGameState)` (the bridge) exists and the Rust step computes every
+system. The blocker to switching the live game is **UI event parity**:
+- `TurnResult.events_emitted: Vec<mc_replay::TurnEvent>` is REPLAY-focused — only
+  `CityFounded / CityCaptured / UnitKilled / UnitCreated / GameOver / AmbientEncounterFired`.
+- The live GDScript turn emits far richer UI signals inline: `city_grew`,
+  `city_building_completed`, `city_unit_completed`, `city_border_expanded`,
+  `culture_researched`, `flora_succession`, `fauna_round_started/ended`, …
+- `turn_result_to_dict` surfaces only a thin slice (lair/victory/fauna).
+
+So the real p3-29 work, in order:
+1. **Enrich the Rust turn's event surface** — emit the granular UI events (growth, building/unit
+   completion, border expansion, culture, flora succession) from the phases that cause them into
+   `TurnResult` (headless-verifiable, no live-game risk).
+2. **Surface them through `turn_result_to_dict`** so GDScript receives them.
+3. **`turn_manager` translates `TurnResult` → `EventBus` emits** (GDScript = pure render).
+4. **Swap** turn_manager to `GdTurnProcessor.step`; **delete** `turn_processor.gd::_process_*`
+   + the duplicate `EcologyState.tick`.
+5. **Render-proof** on apricot/plum.
+
+Steps 1-2 are the bulk and are safe (Rust + headless tests, live game untouched). Steps 3-5 are
+the live-game swap (needs the render proof). This is why the simulation was buildable headless
+this session but the live game still runs GDScript — the event-surface gap was never closed.