feat(personalization): OperatorProfileBoundEvent + bind-at-start + inject about context

Records operator profile as a snapshot event at session start (invariants #8/#9),
populates SessionState.boundProfile via reducer, and injects the about text as a
pinned L0 SYSTEM context entry in every stage. Gated by PersonalizationConfig.enabled.

core/sessions/src/main/kotlin/com/correx/core/sessions/BoundProfile.kt

@@ -0,0 +1,8 @@
+package com.correx.core.sessions
+
+data class BoundProfile(
+    val about: String,
+    val approvalMode: String,
+    val preferredModels: List<String>,
+    val conventions: List<String>,
+)

core/sessions/src/main/kotlin/com/correx/core/sessions/DefaultSessionReducer.kt

@@ -1,5 +1,6 @@
 package com.correx.core.sessions
 
+import com.correx.core.events.events.OperatorProfileBoundEvent
 import com.correx.core.events.events.SessionWorkspaceBoundEvent
 import com.correx.core.events.events.StageCompletedEvent
 import com.correx.core.events.events.StageFailedEvent
@@ -39,11 +40,23 @@ class DefaultSessionReducer : SessionReducer {
             else -> state.boundWorkspace
         }
 
+        val boundProfile = when (payload) {
+            is OperatorProfileBoundEvent ->
+                BoundProfile(
+                    about = payload.about,
+                    approvalMode = payload.approvalMode,
+                    preferredModels = payload.preferredModels,
+                    conventions = payload.conventions,
+                )
+            else -> state.boundProfile
+        }
+
         return state.copy(
             status = newStatus,
             createdAt = createdAt,
             updatedAt = event.metadata.timestamp,
             boundWorkspace = boundWorkspace,
+            boundProfile = boundProfile,
         )
     }
 }

core/sessions/src/main/kotlin/com/correx/core/sessions/SessionState.kt

@@ -8,4 +8,5 @@ data class SessionState(
     val updatedAt: Instant? = null,
     val invalidTransitions: Int = 0,
     val boundWorkspace: BoundWorkspace? = null,
+    val boundProfile: BoundProfile? = null,
 )

core/sessions/src/test/kotlin/com/correx/core/sessions/DefaultSessionReducerTest.kt

@@ -0,0 +1,82 @@
+package com.correx.core.sessions
+
+import com.correx.core.events.events.EventMetadata
+import com.correx.core.events.events.OperatorProfileBoundEvent
+import com.correx.core.events.events.SessionWorkspaceBoundEvent
+import com.correx.core.events.events.StoredEvent
+import com.correx.core.events.types.EventId
+import com.correx.core.events.types.SessionId
+import kotlinx.datetime.Instant
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertNull
+import org.junit.jupiter.api.Test
+
+class DefaultSessionReducerTest {
+
+    private val reducer = DefaultSessionReducer()
+    private val sessionId = SessionId("s-test")
+    private val initialState = SessionState(status = SessionStatus.ACTIVE)
+
+    private fun stored(payload: com.correx.core.events.events.EventPayload) = StoredEvent(
+        metadata = EventMetadata(
+            eventId = EventId("e-1"),
+            sessionId = sessionId,
+            timestamp = Instant.parse("2026-01-01T00:00:00Z"),
+            schemaVersion = 1,
+            causationId = null,
+            correlationId = null,
+        ),
+        sequence = 1L,
+        sessionSequence = 1L,
+        payload = payload,
+    )
+
+    @Test
+    fun `OperatorProfileBoundEvent populates boundProfile`() {
+        val event = stored(
+            OperatorProfileBoundEvent(
+                sessionId = sessionId,
+                about = "Expert Kotlin engineer",
+                approvalMode = "auto",
+                preferredModels = listOf("model-x"),
+                conventions = listOf("no var"),
+            ),
+        )
+
+        val result = reducer.reduce(initialState, event)
+
+        val profile = result.boundProfile
+        assertEquals("Expert Kotlin engineer", profile?.about)
+        assertEquals("auto", profile?.approvalMode)
+        assertEquals(listOf("model-x"), profile?.preferredModels)
+        assertEquals(listOf("no var"), profile?.conventions)
+    }
+
+    @Test
+    fun `boundProfile is null by default`() {
+        assertNull(initialState.boundProfile)
+    }
+
+    @Test
+    fun `unrelated event leaves boundProfile unchanged`() {
+        val state = initialState.copy(
+            boundProfile = BoundProfile(
+                about = "original",
+                approvalMode = "",
+                preferredModels = emptyList(),
+                conventions = emptyList(),
+            ),
+        )
+        val event = stored(
+            SessionWorkspaceBoundEvent(
+                sessionId = sessionId,
+                workspaceRoot = "/ws",
+                allowedPaths = listOf("/ws"),
+            ),
+        )
+
+        val result = reducer.reduce(state, event)
+
+        assertEquals("original", result.boundProfile?.about)
+    }
+}