diff --git a/src/main/java/io/github/legendaryforge/legendary/core/api/activation/ActivationInput.java b/src/main/java/io/github/legendaryforge/legendary/core/api/activation/ActivationInput.java
new file mode 100644
index 0000000..e266d8b
--- /dev/null
+++ b/src/main/java/io/github/legendaryforge/legendary/core/api/activation/ActivationInput.java
@@ -0,0 +1,47 @@
+package io.github.legendaryforge.legendary.core.api.activation;
+
+import io.github.legendaryforge.legendary.core.api.id.ResourceId;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Optional;
+import java.util.UUID;
+
+/**
+ * Server-side resolved activation input passed to gates.
+ *
+ * <p>Attributes must be derived from authoritative state (content/mod owned), not client claims.</p>
+ */
+public final class ActivationInput {
+
+    private final UUID activatorPlayerId;
+    private final ResourceId activationGateKey;
+    private final Map<String, String> attributes;
+    private final Optional<String> targetRef;
+
+    public ActivationInput(
+            UUID activatorPlayerId,
+            ResourceId activationGateKey,
+            Map<String, String> attributes,
+            Optional<String> targetRef) {
+        this.activatorPlayerId = Objects.requireNonNull(activatorPlayerId, "activatorPlayerId");
+        this.activationGateKey = Objects.requireNonNull(activationGateKey, "activationGateKey");
+        this.attributes = Map.copyOf(Objects.requireNonNull(attributes, "attributes"));
+        this.targetRef = Objects.requireNonNull(targetRef, "targetRef");
+    }
+
+    public UUID activatorPlayerId() {
+        return activatorPlayerId;
+    }
+
+    public ResourceId activationGateKey() {
+        return activationGateKey;
+    }
+
+    public Map<String, String> attributes() {
+        return attributes;
+    }
+
+    public Optional<String> targetRef() {
+        return targetRef;
+    }
+}
diff --git a/src/main/java/io/github/legendaryforge/legendary/core/api/activation/ActivationInputResolver.java b/src/main/java/io/github/legendaryforge/legendary/core/api/activation/ActivationInputResolver.java
new file mode 100644
index 0000000..9284d94
--- /dev/null
+++ b/src/main/java/io/github/legendaryforge/legendary/core/api/activation/ActivationInputResolver.java
@@ -0,0 +1,10 @@
+package io.github.legendaryforge.legendary.core.api.activation;
+
+/**
+ * Resolves authoritative activation inputs (attributes/target context) server-side.
+ */
+@FunctionalInterface
+public interface ActivationInputResolver {
+
+    ActivationInput resolve(ActivationService.ActivationAttemptRequest request);
+}
diff --git a/src/main/java/io/github/legendaryforge/legendary/core/api/activation/ActivationService.java b/src/main/java/io/github/legendaryforge/legendary/core/api/activation/ActivationService.java
index 115f0ac..eeedfc1 100644
--- a/src/main/java/io/github/legendaryforge/legendary/core/api/activation/ActivationService.java
+++ b/src/main/java/io/github/legendaryforge/legendary/core/api/activation/ActivationService.java
@@ -15,5 +15,6 @@ record ActivationAttemptRequest(
             EncounterDefinition definition,
             EncounterContext context,
             Optional<ResourceId> activationGateKey,
-            Optional<ActivationAuthority> authorityOverride) {}
+            Optional<ActivationAuthority> authorityOverride,
+            Optional<String> targetRef) {}
 }
diff --git a/src/main/java/io/github/legendaryforge/legendary/core/internal/activation/DefaultActivationService.java b/src/main/java/io/github/legendaryforge/legendary/core/internal/activation/DefaultActivationService.java
index 77be004..a9146b9 100644
--- a/src/main/java/io/github/legendaryforge/legendary/core/internal/activation/DefaultActivationService.java
+++ b/src/main/java/io/github/legendaryforge/legendary/core/internal/activation/DefaultActivationService.java
@@ -3,6 +3,8 @@
 import io.github.legendaryforge.legendary.core.api.activation.ActivationAttemptResult;
 import io.github.legendaryforge.legendary.core.api.activation.ActivationAttemptStatus;
 import io.github.legendaryforge.legendary.core.api.activation.ActivationDecision;
+import io.github.legendaryforge.legendary.core.api.activation.ActivationInput;
+import io.github.legendaryforge.legendary.core.api.activation.ActivationInputResolver;
 import io.github.legendaryforge.legendary.core.api.activation.ActivationService;
 import io.github.legendaryforge.legendary.core.api.activation.session.ActivationSessionBeginResult;
 import io.github.legendaryforge.legendary.core.api.activation.session.ActivationSessionBeginStatus;
@@ -11,7 +13,6 @@
 import io.github.legendaryforge.legendary.core.api.gate.ConditionGate;
 import io.github.legendaryforge.legendary.core.api.gate.GateDecision;
 import io.github.legendaryforge.legendary.core.api.gate.GateService;
-import io.github.legendaryforge.legendary.core.api.id.ResourceId;
 import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
@@ -20,10 +21,17 @@ public final class DefaultActivationService implements ActivationService {
 
     private final GateService gates;
     private final ActivationSessionService sessions;
+    private final ActivationInputResolver inputResolver;
 
     public DefaultActivationService(GateService gates, ActivationSessionService sessions) {
+        this(gates, sessions, DefaultActivationService::defaultResolve);
+    }
+
+    public DefaultActivationService(
+            GateService gates, ActivationSessionService sessions, ActivationInputResolver inputResolver) {
         this.gates = Objects.requireNonNull(gates, "gates");
         this.sessions = Objects.requireNonNull(sessions, "sessions");
+        this.inputResolver = Objects.requireNonNull(inputResolver, "inputResolver");
     }
 
     @Override
@@ -34,59 +42,52 @@ public ActivationAttemptResult attemptActivation(ActivationAttemptRequest reques
 
         // Phase 2: evaluate activation gate (if present)
         ActivationDecision decision = request.activationGateKey()
-                .map(gateKey -> evaluateGate(gateKey, request, encounterKey))
+                .map(ignored -> evaluateGate(inputResolver.resolve(request), encounterKey))
                 .orElseGet(ActivationDecision::allow);
 
         if (!decision.allowed()) {
             return new ActivationAttemptResult(
-                    ActivationAttemptStatus.FAILED,
-                    decision,
-                    Optional.empty(),
-                    Optional.empty());
+                    ActivationAttemptStatus.FAILED, decision, Optional.empty(), Optional.empty());
         }
 
         // Phase 2: begin activation session
-        ActivationSessionBeginResult begin = sessions.begin(
-                new ActivationSessionService.ActivationSessionBeginRequest(
-                        request.activatorId(),
-                        encounterKey,
-                        request.definition(),
-                        request.context(),
-                        request.activationGateKey(),
-                        decision.attributes()
-                )
-        );
+        ActivationSessionBeginResult begin = sessions.begin(new ActivationSessionService.ActivationSessionBeginRequest(
+                request.activatorId(),
+                encounterKey,
+                request.definition(),
+                request.context(),
+                request.activationGateKey(),
+                decision.attributes()));
 
-        if (begin.status() == ActivationSessionBeginStatus.CREATED || begin.status() == ActivationSessionBeginStatus.EXISTING) {
+        if (begin.status() == ActivationSessionBeginStatus.CREATED
+                || begin.status() == ActivationSessionBeginStatus.EXISTING) {
             return new ActivationAttemptResult(
-                    ActivationAttemptStatus.SUCCESS,
-                    decision,
-                    Optional.of(begin.sessionId()),
-                    Optional.empty());
+                    ActivationAttemptStatus.SUCCESS, decision, Optional.of(begin.sessionId()), Optional.empty());
         }
 
         // DENIED => FAILED
         ActivationDecision denied = ActivationDecision.deny(begin.reasonCode(), decision.attributes());
-        return new ActivationAttemptResult(
-                ActivationAttemptStatus.FAILED,
-                denied,
-                Optional.empty(),
-                Optional.empty());
+        return new ActivationAttemptResult(ActivationAttemptStatus.FAILED, denied, Optional.empty(), Optional.empty());
     }
 
-    private ActivationDecision evaluateGate(ResourceId gateKey, ActivationAttemptRequest request, EncounterKey encounterKey) {
+    private ActivationDecision evaluateGate(ActivationInput input, EncounterKey encounterKey) {
         ConditionGate.GateRequest gateRequest = new ConditionGate.GateRequest(
-                gateKey,
-                request.activatorId(),
+                input.activationGateKey(),
+                input.activatorPlayerId(),
                 Optional.of(encounterKey),
                 Optional.empty(),
                 Optional.empty(),
-                Map.of()
-        );
+                input.attributes());
 
         GateDecision gateDecision = gates.evaluate(gateRequest);
         return gateDecision.allowed()
                 ? ActivationDecision.allow()
                 : ActivationDecision.deny(gateDecision.reasonCode(), gateDecision.attributes());
     }
+
+    private static ActivationInput defaultResolve(ActivationAttemptRequest request) {
+        // Only invoked when request.activationGateKey() is present (see attemptActivation).
+        return new ActivationInput(
+                request.activatorId(), request.activationGateKey().orElseThrow(), Map.of(), request.targetRef());
+    }
 }
diff --git a/src/main/java/io/github/legendaryforge/legendary/core/internal/runtime/DefaultCoreRuntime.java b/src/main/java/io/github/legendaryforge/legendary/core/internal/runtime/DefaultCoreRuntime.java
index 023b76b..c0e52ba 100644
--- a/src/main/java/io/github/legendaryforge/legendary/core/internal/runtime/DefaultCoreRuntime.java
+++ b/src/main/java/io/github/legendaryforge/legendary/core/internal/runtime/DefaultCoreRuntime.java
@@ -1,5 +1,7 @@
 package io.github.legendaryforge.legendary.core.internal.runtime;
 
+import io.github.legendaryforge.legendary.core.api.activation.ActivationInput;
+import io.github.legendaryforge.legendary.core.api.activation.ActivationInputResolver;
 import io.github.legendaryforge.legendary.core.api.activation.ActivationService;
 import io.github.legendaryforge.legendary.core.api.activation.session.ActivationSessionService;
 import io.github.legendaryforge.legendary.core.api.encounter.EncounterManager;
@@ -35,17 +37,12 @@
 import io.github.legendaryforge.legendary.core.internal.lifecycle.DefaultServiceRegistry;
 import io.github.legendaryforge.legendary.core.internal.registry.DefaultRegistryAccess;
 import java.time.Clock;
+import java.util.Map;
 import java.util.Objects;
 import java.util.Optional;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
-/**
- * Default internal wiring of LegendaryCore runtime components.
- *
- * <p>This provides a platform-agnostic reference implementation that platform adapters may
- * construct and delegate to.</p>
- */
 public final class DefaultCoreRuntime implements CoreRuntime {
 
     private final RegistryAccess registries;
@@ -59,9 +56,6 @@ public final class DefaultCoreRuntime implements CoreRuntime {
     private final Optional<PlayerDirectory> players;
     private final Optional<PartyDirectory> parties;
 
-    /**
-     * Platform-agnostic default constructor using the internal reference EncounterManager.
-     */
     public DefaultCoreRuntime() {
         this(Optional.empty(), Optional.empty(), Clock.systemUTC());
     }
@@ -121,7 +115,10 @@ public DefaultCoreRuntime(Optional<PlayerDirectory> players, Optional<PartyDirec
         ActivationSessionService sessions = new DefaultActivationSessionService();
         this.services.register(ActivationSessionService.class, sessions);
 
-        ActivationService activations = new DefaultActivationService(gates, sessions);
+        ActivationInputResolver activationInputs = request -> new ActivationInput(
+                request.activatorId(), request.activationGateKey().orElseThrow(), Map.of(), request.targetRef());
+
+        ActivationService activations = new DefaultActivationService(gates, sessions, activationInputs);
         this.services.register(ActivationService.class, activations);
 
         bus.subscribe(
@@ -141,33 +138,6 @@ public DefaultCoreRuntime(Optional<PlayerDirectory> players, Optional<PartyDirec
         this.parties = Objects.requireNonNull(parties, "parties");
     }
 
-    public DefaultCoreRuntime(EncounterManager encounters) {
-        this(encounters, Optional.empty(), Optional.empty());
-    }
-
-    private DefaultCoreRuntime(
-            EncounterManager encounters,
-            EventBus events,
-            Optional<PlayerDirectory> players,
-            Optional<PartyDirectory> parties) {
-        this.registries = new DefaultRegistryAccess();
-
-        DefaultLifecycle lifecycle = new DefaultLifecycle();
-        this.lifecycle = lifecycle;
-
-        this.services = new DefaultServiceRegistry(lifecycle);
-        this.events = java.util.Objects.requireNonNull(events, "events");
-        this.clock = Clock.systemUTC();
-        this.encounters = java.util.Objects.requireNonNull(encounters, "encounters");
-        this.players = java.util.Objects.requireNonNull(players, "players");
-        this.parties = java.util.Objects.requireNonNull(parties, "parties");
-    }
-
-    private DefaultCoreRuntime(
-            EncounterManager encounters, Optional<PlayerDirectory> players, Optional<PartyDirectory> parties) {
-        this(encounters, new SimpleEventBus(), players, parties);
-    }
-
     @Override
     public RegistryAccess registries() {
         return registries;