diff --git a/core/events/build.gradle b/core/events/build.gradle
index d1429deb..37f5b943 100644
--- a/core/events/build.gradle
+++ b/core/events/build.gradle
@@ -7,5 +7,6 @@ plugins {
 dependencies {
     implementation "org.jetbrains.kotlinx:kotlinx-datetime"
     implementation "org.jetbrains.kotlinx:kotlinx-coroutines-core:$kotlinx_coroutines_version"
+    testImplementation "org.jetbrains.kotlin:kotlin-test"
 }
 tasks.named("koverVerify").configure { enabled = false }
diff --git a/core/events/src/main/kotlin/com/correx/core/events/events/ToolCallAssessmentEvents.kt b/core/events/src/main/kotlin/com/correx/core/events/events/ToolCallAssessmentEvents.kt
new file mode 100644
index 00000000..278a249c
--- /dev/null
+++ b/core/events/src/main/kotlin/com/correx/core/events/events/ToolCallAssessmentEvents.kt
@@ -0,0 +1,34 @@
+package com.correx.core.events.events
+
+import com.correx.core.events.risk.RiskAction
+import com.correx.core.events.types.SessionId
+import com.correx.core.events.types.StageId
+import com.correx.core.events.types.ToolInvocationId
+import kotlinx.serialization.SerialName
+import kotlinx.serialization.Serializable
+
+@Serializable
+data class AssessedIssue(
+    val code: String,
+    val message: String,
+    val severity: String,
+)
+
+@Serializable
+data class ToolCallObservation(
+    val ruleCode: String,
+    val facts: Map<String, String> = emptyMap(),
+)
+
+@Serializable
+@SerialName("ToolCallAssessed")
+data class ToolCallAssessedEvent(
+    val invocationId: ToolInvocationId,
+    val sessionId: SessionId,
+    val stageId: StageId,
+    val toolName: String,
+    val issues: List<AssessedIssue> = emptyList(),
+    val observations: List<ToolCallObservation> = emptyList(),
+    val disposition: RiskAction,
+    val timestampMs: Long,
+) : EventPayload
diff --git a/core/events/src/main/kotlin/com/correx/core/events/serialization/Serialization.kt b/core/events/src/main/kotlin/com/correx/core/events/serialization/Serialization.kt
index 62d82958..5a455d79 100644
--- a/core/events/src/main/kotlin/com/correx/core/events/serialization/Serialization.kt
+++ b/core/events/src/main/kotlin/com/correx/core/events/serialization/Serialization.kt
@@ -25,6 +25,7 @@ import com.correx.core.events.events.RiskAssessedEvent
 import com.correx.core.events.events.StageCompletedEvent
 import com.correx.core.events.events.StageFailedEvent
 import com.correx.core.events.events.SteeringNoteAddedEvent
+import com.correx.core.events.events.ToolCallAssessedEvent
 import com.correx.core.events.events.ToolExecutionCompletedEvent
 import com.correx.core.events.events.ToolExecutionFailedEvent
 import com.correx.core.events.events.ToolExecutionRejectedEvent
@@ -49,6 +50,7 @@ val eventModule = SerializersModule {
         subclass(ToolExecutionCompletedEvent::class)
         subclass(ToolExecutionFailedEvent::class)
         subclass(ToolExecutionRejectedEvent::class)
+        subclass(ToolCallAssessedEvent::class)
         subclass(SteeringNoteAddedEvent::class)
         subclass(StageFailedEvent::class)
         subclass(StageCompletedEvent::class)
diff --git a/core/events/src/test/kotlin/com/correx/core/events/serialization/ToolCallAssessedEventSerializationTest.kt b/core/events/src/test/kotlin/com/correx/core/events/serialization/ToolCallAssessedEventSerializationTest.kt
new file mode 100644
index 00000000..8e469e1c
--- /dev/null
+++ b/core/events/src/test/kotlin/com/correx/core/events/serialization/ToolCallAssessedEventSerializationTest.kt
@@ -0,0 +1,51 @@
+package com.correx.core.events.serialization
+
+import com.correx.core.events.events.AssessedIssue
+import com.correx.core.events.events.EventPayload
+import com.correx.core.events.events.ToolCallAssessedEvent
+import com.correx.core.events.events.ToolCallObservation
+import com.correx.core.events.risk.RiskAction
+import com.correx.core.events.types.SessionId
+import com.correx.core.events.types.StageId
+import com.correx.core.events.types.ToolInvocationId
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+
+class ToolCallAssessedEventSerializationTest {
+
+    private val sample = ToolCallAssessedEvent(
+        invocationId = ToolInvocationId("inv-1"),
+        sessionId = SessionId("sess-1"),
+        stageId = StageId("stage-1"),
+        toolName = "file_write",
+        issues = listOf(AssessedIssue("PATH_OUTSIDE_WORKSPACE", "outside: /tmp/x", "WARNING")),
+        observations = listOf(
+            ToolCallObservation(
+                ruleCode = "PATH_CONTAINMENT",
+                facts = mapOf("path" to "/tmp/x", "exists" to "false", "inWorkspace" to "false", "privileged" to "false"),
+            ),
+        ),
+        disposition = RiskAction.PROMPT_USER,
+        timestampMs = 42L,
+    )
+
+    @Test
+    fun `round-trips as polymorphic EventPayload`() {
+        val encoded = eventJson.encodeToString(EventPayload.serializer(), sample)
+        assertTrue(encoded.contains("\"type\":\"ToolCallAssessed\""), "SerialName must be present: $encoded")
+        val decoded = eventJson.decodeFromString(EventPayload.serializer(), encoded)
+        assertEquals(sample, decoded)
+    }
+
+    @Test
+    fun `decodes hand-written ToolCallAssessed JSON`() {
+        val json = """
+            {"type":"ToolCallAssessed","invocationId":"inv-9","sessionId":"s","stageId":"st",
+             "toolName":"shell","issues":[],"observations":[],"disposition":"PROCEED","timestampMs":1}
+        """.trimIndent()
+        val decoded = eventJson.decodeFromString(EventPayload.serializer(), json)
+        assertTrue(decoded is ToolCallAssessedEvent)
+        assertEquals(RiskAction.PROCEED, (decoded as ToolCallAssessedEvent).disposition)
+    }
+}