diff --git a/src/simulator/crates/mc-turn/src/processor.rs b/src/simulator/crates/mc-turn/src/processor.rs
index 9384eedf..377abef9 100644
--- a/src/simulator/crates/mc-turn/src/processor.rs
+++ b/src/simulator/crates/mc-turn/src/processor.rs
@@ -3459,9 +3459,39 @@ impl TurnProcessor {
                 // last city is captured. Matches the
                 // `eliminated_player_skipped_in_domination` test's manual
                 // setup at `victory.rs:798` (`p1.capital_position = None`).
-                if defender.capital_position == Some(pos) {
+                //
+                // Communications Phase 6 wiring: when the defender's
+                // capital is lost (and they still have surviving cities),
+                // begin a comms blackout. Drops in-flight outbound
+                // envelopes, penalises comm-tier, accelerates last-seen
+                // decay. Emits `CapitalBlackoutBegan` for the replay
+                // viewer; the next-turn handler enforces the 1-turn UX
+                // gate per `project_capital_blackout_design.md`.
+                let lost_capital = defender.capital_position == Some(pos);
+                if lost_capital {
                     defender.capital_position = None;
                 }
+                let defender_cities_remaining = !defender.cities.is_empty();
+                // End the &mut state.players[defender_pi] borrow before
+                // touching state.comms (also a child of state).
+                let _ = defender;
+                if lost_capital && defender_cities_remaining {
+                    let turn_now = state.turn;
+                    mc_comms::blackout::begin_blackout(
+                        &mut state.comms,
+                        defender_pi as u8,
+                        turn_now,
+                    );
+                    result.events_emitted.push(
+                        mc_replay::TurnEvent::CapitalBlackoutBegan {
+                            turn: turn_now,
+                            player: mc_replay::ClanId(defender_pi as u32),
+                            lost_capital_hex: mc_replay::TileCoord::new(
+                                pos.0, pos.1,
+                            ),
+                        },
+                    );
+                }
 
                 // Transfer to attacker.
                 let attacker = &mut state.players[attacker_pi];
diff --git a/src/simulator/crates/mc-turn/tests/event_collector_wiring.rs b/src/simulator/crates/mc-turn/tests/event_collector_wiring.rs
index c8e424c0..1446d661 100644
--- a/src/simulator/crates/mc-turn/tests/event_collector_wiring.rs
+++ b/src/simulator/crates/mc-turn/tests/event_collector_wiring.rs
@@ -232,6 +232,13 @@ fn ten_turn_run_emits_each_wired_variant() {
             TurnEvent::HeartbeatMissed { .. } => "HeartbeatMissed",
             TurnEvent::VisionShareCollapsed { .. } => "VisionShareCollapsed",
             TurnEvent::VisionShareRestored { .. } => "VisionShareRestored",
+            // Communications Phase 6 (envelope-flow + link-flow) — labelled
+            // for exhaustiveness; the 10-turn fixture does not exercise them.
+            TurnEvent::EnvelopeDispatched { .. } => "EnvelopeDispatched",
+            TurnEvent::EnvelopeDelivered { .. } => "EnvelopeDelivered",
+            TurnEvent::EnvelopeIntercepted { .. } => "EnvelopeIntercepted",
+            TurnEvent::LinkSevered { .. } => "LinkSevered",
+            TurnEvent::LinkRestored { .. } => "LinkRestored",
         })
         .collect();