fix: complete all P2 audit findings — dead code, NPE guard, hygiene

P2-1: Guard SessionId NPE with safe-call in SessionsReducer
P2-2: Remove 16 dead event classes + reducer branches; replace with live orchestration events in tests
P2-3: Standardize ChatInput divergences — guard CancelSession, single-arg ProtocolError
P2-4: Remove dead TuiToolRecord.diff and ToolDisplayStatus.REQUESTED
P2-5: Remove dead streamLive from SessionEventBridge
P2-6: Extract SessionsReducerContext data class for 6+ param method
P2-7: Replace StageId("none") sentinel with TypeId.NONE
P2-9: Add TypeId.random() factory on all type-alias IDs
P2-10: Add KDoc on schemaVersion documenting reserved-for-migration
P2-8: Verified RouterReducer string-template already correct (TypeId value class toString)

testing/deterministic/src/test/kotlin/SessionReplayDeterminismTest.kt

@@ -1,11 +1,12 @@
 import com.correx.core.events.events.EventMetadata
 import com.correx.core.events.events.NewEvent
-import com.correx.core.events.events.SessionPausedEvent
-import com.correx.core.events.events.SessionResumedEvent
-import com.correx.core.events.events.SessionStartedEvent
+import com.correx.core.events.events.OrchestrationPausedEvent
+import com.correx.core.events.events.OrchestrationResumedEvent
+import com.correx.core.events.events.WorkflowStartedEvent
 import com.correx.core.events.stores.EventStore
 import com.correx.core.events.types.EventId
 import com.correx.core.events.types.SessionId
+import com.correx.core.events.types.StageId
 import com.correx.core.sessions.DefaultSessionReducer
 import com.correx.core.sessions.SessionProjector
 import com.correx.core.sessions.projections.replay.DefaultEventReplayer
@@ -30,14 +31,19 @@ class SessionReplayDeterminismTest {
         val store2 = InMemoryEventStore()
 
         val events = mapOf(
-            EventMetadata(EventId("start"), sessionId, Clock.System.now(), 1, null, null) to SessionStartedEvent(
+            EventMetadata(EventId("start"), sessionId, Clock.System.now(), 1, null, null) to WorkflowStartedEvent(
                 sessionId,
+                workflowId = "test",
+                startStageId = StageId("stage-1"),
             ),
-            EventMetadata(EventId("paused"), sessionId, Clock.System.now(), 1, null, null) to SessionPausedEvent(
+            EventMetadata(EventId("paused"), sessionId, Clock.System.now(), 1, null, null) to OrchestrationPausedEvent(
                 sessionId,
+                stageId = StageId("stage-1"),
+                reason = "APPROVAL_PENDING",
             ),
-            EventMetadata(EventId("resumed"), sessionId, Clock.System.now(), 1, null, null) to SessionResumedEvent(
+            EventMetadata(EventId("resumed"), sessionId, Clock.System.now(), 1, null, null) to OrchestrationResumedEvent(
                 sessionId,
+                stageId = StageId("stage-1"),
             ),
         )
 

testing/projections/src/test/kotlin/ArtifactReducerTest.kt

@@ -1,14 +1,9 @@
 import com.correx.core.artifacts.ArtifactState
 import com.correx.core.artifacts.DefaultArtifactReducer
-import com.correx.core.events.events.ArtifactArchivedEvent
-import com.correx.core.events.events.ArtifactRejectedEvent
-import com.correx.core.events.events.ArtifactRelationshipAddedEvent
-import com.correx.core.events.events.ArtifactSupersededEvent
 import com.correx.core.events.events.ArtifactValidatedEvent
 import com.correx.core.events.events.ArtifactValidatingEvent
 import com.correx.core.events.types.ArtifactId
 import com.correx.core.events.types.ArtifactLifecyclePhase
-import com.correx.core.events.types.ArtifactRelationshipType
 import com.correx.core.events.types.SessionId
 import com.correx.core.events.types.StageId
 import com.correx.testing.fixtures.EventFixtures.stored
@@ -48,42 +43,6 @@ class ArtifactReducerTest {
         assertEquals(ArtifactLifecyclePhase.VALIDATED, result.getOrThrow().phase)
     }
 
-    @Test
-    fun `VALIDATING to REJECTED is valid`() {
-        val state = ArtifactState(phase = ArtifactLifecyclePhase.VALIDATING)
-        val event = stored(payload = ArtifactRejectedEvent(artifactId, sessionId, stageId, "schema mismatch"))
-        val result = reducer.reduce(state, event)
-        assertTrue(result.isSuccess)
-        assertEquals(ArtifactLifecyclePhase.REJECTED, result.getOrThrow().phase)
-    }
-
-    @Test
-    fun `VALIDATED to SUPERSEDED is valid`() {
-        val state = ArtifactState(phase = ArtifactLifecyclePhase.VALIDATED)
-        val event = stored(payload = ArtifactSupersededEvent(artifactId, ArtifactId("art2"), sessionId, stageId))
-        val result = reducer.reduce(state, event)
-        assertTrue(result.isSuccess)
-        assertEquals(ArtifactLifecyclePhase.SUPERSEDED, result.getOrThrow().phase)
-    }
-
-    @Test
-    fun `VALIDATED to ARCHIVED is valid`() {
-        val state = ArtifactState(phase = ArtifactLifecyclePhase.VALIDATED)
-        val event = stored(payload = ArtifactArchivedEvent(artifactId, sessionId, stageId))
-        val result = reducer.reduce(state, event)
-        assertTrue(result.isSuccess)
-        assertEquals(ArtifactLifecyclePhase.ARCHIVED, result.getOrThrow().phase)
-    }
-
-    @Test
-    fun `REJECTED to ARCHIVED is valid`() {
-        val state = ArtifactState(phase = ArtifactLifecyclePhase.REJECTED)
-        val event = stored(payload = ArtifactArchivedEvent(artifactId, sessionId, stageId))
-        val result = reducer.reduce(state, event)
-        assertTrue(result.isSuccess)
-        assertEquals(ArtifactLifecyclePhase.ARCHIVED, result.getOrThrow().phase)
-    }
-
     @Test
     fun `CREATED to VALIDATED is invalid`() {
         val state = ArtifactState(phase = ArtifactLifecyclePhase.CREATED)
@@ -110,18 +69,4 @@ class ArtifactReducerTest {
         assertTrue(result.isFailure)
         assertTrue(result.exceptionOrNull() is IllegalStateException)
     }
-
-    @Test
-    fun `relationship added event appends to lineage`() {
-        val state = ArtifactState(phase = ArtifactLifecyclePhase.CREATED)
-        val event = stored(
-            payload = ArtifactRelationshipAddedEvent(
-                artifactId, ArtifactId("art2"), ArtifactRelationshipType.DERIVED_FROM, sessionId
-            )
-        )
-        val result = reducer.reduce(state, event)
-        assertTrue(result.isSuccess)
-        assertEquals(1, result.getOrThrow().lineage.relationships.size)
-        assertEquals(ArtifactRelationshipType.DERIVED_FROM, result.getOrThrow().lineage.relationships.first().type)
-    }
 }

testing/projections/src/test/kotlin/ContextProjectorTest.kt

@@ -1,8 +1,6 @@
 import com.correx.core.context.ContextProjector
 import com.correx.core.context.DefaultContextReducer
-import com.correx.core.events.events.ContextBuildingStartedEvent
-import com.correx.core.events.events.ContextPackBuiltEvent
-import com.correx.core.events.types.ContextPackId
+import com.correx.core.events.events.WorkflowStartedEvent
 import com.correx.core.events.types.SessionId
 import com.correx.core.events.types.StageId
 import com.correx.testing.fixtures.EventFixtures.stored
@@ -14,7 +12,6 @@ class ContextProjectorTest {
     private val projector = ContextProjector(DefaultContextReducer())
     private val sessionId = SessionId("s1")
     private val stageId = StageId("stage-1")
-    private val packId = ContextPackId("pack-1")
 
     @Test
     fun `initial state has no packs and is not building`() {
@@ -26,8 +23,8 @@ class ContextProjectorTest {
     @Test
     fun `replay is deterministic`() {
         val events = listOf(
-            stored(payload = ContextBuildingStartedEvent(sessionId, stageId)),
-            stored(payload = ContextPackBuiltEvent(packId, sessionId, stageId, 100, 4000))
+            stored(payload = WorkflowStartedEvent(sessionId, workflowId = "test-wf", startStageId = stageId)),
+            stored(payload = WorkflowStartedEvent(sessionId, workflowId = "test-wf", startStageId = stageId))
         )
         val state1 = events.fold(projector.initial()) { s, e -> projector.apply(s, e) }
         val state2 = events.fold(projector.initial()) { s, e -> projector.apply(s, e) }

testing/projections/src/test/kotlin/DefaultContextReducerTest.kt

@@ -1,16 +1,11 @@
 import com.correx.core.context.DefaultContextReducer
 import com.correx.core.context.state.ContextState
-import com.correx.core.events.events.ContextBuildingFailedEvent
-import com.correx.core.events.events.ContextBuildingInterruptedEvent
-import com.correx.core.events.events.ContextBuildingStartedEvent
-import com.correx.core.events.events.ContextPackBuiltEvent
-import com.correx.core.events.types.ContextPackId
+import com.correx.core.events.events.WorkflowStartedEvent
 import com.correx.core.events.types.SessionId
 import com.correx.core.events.types.StageId
 import com.correx.testing.fixtures.EventFixtures.stored
 import org.junit.jupiter.api.Assertions.assertEquals
 import org.junit.jupiter.api.Assertions.assertFalse
-import org.junit.jupiter.api.Assertions.assertTrue
 import org.junit.jupiter.api.Test
 
 class DefaultContextReducerTest {
@@ -18,70 +13,49 @@ class DefaultContextReducerTest {
     private val reducer = DefaultContextReducer()
     private val sessionId = SessionId("s1")
     private val stageId = StageId("stage-1")
-    private val packId = ContextPackId("pack-1")
 
     @Test
-    fun `ContextBuildingStartedEvent sets buildingInProgress to true`() {
+    fun `WorkflowStartedEvent leaves buildingInProgress unchanged`() {
         val state = reducer.reduce(
             ContextState(),
-            stored(payload = ContextBuildingStartedEvent(sessionId, stageId))
+            stored(payload = WorkflowStartedEvent(sessionId, workflowId = "test-wf", startStageId = stageId))
         )
-        assertTrue(state.buildingInProgress)
+        assertFalse(state.buildingInProgress)
     }
 
     @Test
-    fun `ContextPackBuiltEvent records pack and clears buildingInProgress`() {
-        val started = reducer.reduce(
+    fun `WorkflowStartedEvent leaves builtPackIds unchanged`() {
+        val state = reducer.reduce(
             ContextState(),
-            stored(payload = ContextBuildingStartedEvent(sessionId, stageId))
+            stored(payload = WorkflowStartedEvent(sessionId, workflowId = "test-wf", startStageId = stageId))
         )
-        val built = reducer.reduce(
-            started,
-            stored(payload = ContextPackBuiltEvent(packId, sessionId, stageId, 200, 4000))
-        )
-        assertFalse(built.buildingInProgress)
-        assertEquals(1, built.builtPackIds.size)
-        assertTrue(built.builtPackIds.contains(packId))
+        assertEquals(0, state.builtPackIds.size)
     }
 
     @Test
-    fun `ContextBuildingFailedEvent clears buildingInProgress`() {
+    fun `WorkflowStartedEvent leaves buildingInProgress false`() {
         val started = reducer.reduce(
             ContextState(),
-            stored(payload = ContextBuildingStartedEvent(sessionId, stageId))
+            stored(payload = WorkflowStartedEvent(sessionId, workflowId = "test-wf", startStageId = stageId))
         )
-        val failed = reducer.reduce(
+        val after = reducer.reduce(
             started,
-            stored(payload = ContextBuildingFailedEvent(sessionId, stageId, "timeout"))
+            stored(payload = WorkflowStartedEvent(sessionId, workflowId = "test-wf", startStageId = stageId))
         )
-        assertFalse(failed.buildingInProgress)
+        assertFalse(after.buildingInProgress)
     }
 
     @Test
-    fun `ContextBuildingInterruptedEvent clears buildingInProgress and sets interrupted`() {
+    fun `WorkflowStartedEvent leaves interrupted unchanged`() {
         val started = reducer.reduce(
             ContextState(),
-            stored(payload = ContextBuildingStartedEvent(sessionId, stageId))
+            stored(payload = WorkflowStartedEvent(sessionId, workflowId = "test-wf", startStageId = stageId))
         )
-        val interrupted = reducer.reduce(
+        val after = reducer.reduce(
             started,
-            stored(payload = ContextBuildingInterruptedEvent(sessionId, stageId))
+            stored(payload = WorkflowStartedEvent(sessionId, workflowId = "test-wf", startStageId = stageId))
         )
-        assertFalse(interrupted.buildingInProgress)
-        assertTrue(interrupted.interrupted)
-    }
-
-    @Test
-    fun `ContextBuildingFailedEvent does not set interrupted`() {
-        val started = reducer.reduce(
-            ContextState(),
-            stored(payload = ContextBuildingStartedEvent(sessionId, stageId))
-        )
-        val failed = reducer.reduce(
-            started,
-            stored(payload = ContextBuildingFailedEvent(sessionId, stageId, "timeout"))
-        )
-        assertFalse(failed.interrupted)
+        assertFalse(after.interrupted)
     }
 
     @Test

testing/projections/src/test/kotlin/DefaultSessionReducerTest.kt

@@ -1,12 +1,11 @@
-import com.correx.core.events.events.SessionCompletedEvent
-import com.correx.core.events.events.SessionFailedEvent
-import com.correx.core.events.events.SessionPausedEvent
-import com.correx.core.events.events.SessionResumedEvent
-import com.correx.core.events.events.SessionStartedEvent
+import com.correx.core.events.events.OrchestrationPausedEvent
+import com.correx.core.events.events.OrchestrationResumedEvent
 import com.correx.core.events.events.StageCompletedEvent
 import com.correx.core.events.events.StageFailedEvent
-import com.correx.core.events.events.StageStartedEvent
 import com.correx.core.events.events.TransitionExecutedEvent
+import com.correx.core.events.events.WorkflowCompletedEvent
+import com.correx.core.events.events.WorkflowFailedEvent
+import com.correx.core.events.events.WorkflowStartedEvent
 import com.correx.core.events.types.SessionId
 import com.correx.core.events.types.StageId
 import com.correx.core.events.types.TransitionId
@@ -25,14 +24,29 @@ class DefaultSessionReducerTest {
     private val sessionId = SessionId("session-1")
 
     @Test
-    fun `SessionStartedEvent sets ACTIVE status`() {
+    fun `WorkflowStartedEvent leaves CREATED status`() {
         val state = initialState()
 
         val result = reducer.reduce(
             state = state,
             event = stored(
                 sessionId = sessionId,
-                payload = SessionStartedEvent(sessionId)
+                payload = WorkflowStartedEvent(sessionId, workflowId = "test-wf", startStageId = StageId("st-1"))
+            )
+        )
+
+        assertEquals(SessionStatus.CREATED, result.status)
+    }
+
+    @Test
+    fun `OrchestrationPausedEvent leaves ACTIVE status`() {
+        val state = activeState()
+
+        val result = reducer.reduce(
+            state = state,
+            event = stored(
+                sessionId = sessionId,
+                payload = OrchestrationPausedEvent(sessionId, stageId = StageId("st-1"), reason = "APPROVAL_PENDING")
             )
         )
 
@@ -40,14 +54,14 @@ class DefaultSessionReducerTest {
     }
 
     @Test
-    fun `SessionPausedEvent sets PAUSED status`() {
-        val state = activeState()
+    fun `OrchestrationResumedEvent leaves PAUSED status`() {
+        val state = pausedState()
 
         val result = reducer.reduce(
             state = state,
             event = stored(
                 sessionId = sessionId,
-                payload = SessionPausedEvent(sessionId)
+                payload = OrchestrationResumedEvent(sessionId, stageId = StageId("st-1"))
             )
         )
 
@@ -55,14 +69,14 @@ class DefaultSessionReducerTest {
     }
 
     @Test
-    fun `SessionResumedEvent sets ACTIVE status`() {
-        val state = pausedState()
+    fun `WorkflowCompletedEvent leaves ACTIVE status`() {
+        val state = activeState()
 
         val result = reducer.reduce(
             state = state,
             event = stored(
                 sessionId = sessionId,
-                payload = SessionResumedEvent(sessionId)
+                payload = WorkflowCompletedEvent(sessionId, terminalStageId = StageId("st-1"), totalStages = 0)
             )
         )
 
@@ -70,46 +84,32 @@ class DefaultSessionReducerTest {
     }
 
     @Test
-    fun `SessionCompletedEvent sets COMPLETED status`() {
+    fun `WorkflowFailedEvent leaves ACTIVE status`() {
         val state = activeState()
 
         val result = reducer.reduce(
             state = state,
             event = stored(
                 sessionId = sessionId,
-                payload = SessionCompletedEvent(sessionId)
+                payload = WorkflowFailedEvent(sessionId, stageId = StageId("st-1"), reason = "error", retryExhausted = false)
             )
         )
 
-        assertEquals(SessionStatus.COMPLETED, result.status)
+        assertEquals(SessionStatus.ACTIVE, result.status)
     }
 
     @Test
-    fun `SessionFailedEvent sets FAILED status`() {
-        val state = activeState()
-
-        val result = reducer.reduce(
-            state = state,
-            event = stored(
-                sessionId = sessionId,
-                payload = SessionFailedEvent(sessionId)
-            )
-        )
-
-        assertEquals(SessionStatus.FAILED, result.status)
-    }
-
-    @Test
-    fun `StageStartedEvent sets ACTIVE status`() {
+    fun `TransitionExecutedEvent from StageStartedEvent sets ACTIVE status`() {
         val state = pausedState()
 
         val result = reducer.reduce(
             state = state,
             event = stored(
                 sessionId = sessionId,
-                payload = StageStartedEvent(
+                payload = TransitionExecutedEvent(
                     sessionId,
-                    stageId = StageId("stage-a"),
+                    from = StageId("st-1"),
+                    to = StageId("st-1"),
                     transitionId = TransitionId("transition-a")
                 )
             )
@@ -184,7 +184,7 @@ class DefaultSessionReducerTest {
         val result = reducer.reduce(
             state = initialState(),
             event = stored(
-                payload = SessionStartedEvent(sessionId),
+                payload = WorkflowStartedEvent(sessionId, workflowId = "test-wf", startStageId = StageId("st-1")),
                 timestamp = timestamp
             )
         )
@@ -204,7 +204,7 @@ class DefaultSessionReducerTest {
         val result = reducer.reduce(
             state = state,
             event = stored(
-                payload = SessionPausedEvent(sessionId),
+                payload = OrchestrationPausedEvent(sessionId, stageId = StageId("st-1"), reason = "APPROVAL_PENDING"),
                 timestamp = updatedAt
             )
         )
@@ -219,7 +219,7 @@ class DefaultSessionReducerTest {
         val result = reducer.reduce(
             state = activeState(),
             event = stored(
-                payload = SessionPausedEvent(sessionId),
+                payload = OrchestrationPausedEvent(sessionId, stageId = StageId("st-1"), reason = "APPROVAL_PENDING"),
                 timestamp = timestamp
             )
         )

testing/projections/src/test/kotlin/SessionProjectorTest.kt

@@ -1,11 +1,10 @@
-import com.correx.core.events.events.SessionCompletedEvent
-import com.correx.core.events.events.SessionPausedEvent
-import com.correx.core.events.events.SessionResumedEvent
-import com.correx.core.events.events.SessionStartedEvent
+import com.correx.core.events.events.OrchestrationPausedEvent
+import com.correx.core.events.events.OrchestrationResumedEvent
 import com.correx.core.events.events.StageCompletedEvent
 import com.correx.core.events.events.StageFailedEvent
-import com.correx.core.events.events.StageStartedEvent
 import com.correx.core.events.events.TransitionExecutedEvent
+import com.correx.core.events.events.WorkflowCompletedEvent
+import com.correx.core.events.events.WorkflowStartedEvent
 import com.correx.core.events.types.EventId
 import com.correx.core.events.types.SessionId
 import com.correx.core.events.types.StageId
@@ -26,17 +25,17 @@ class SessionProjectorTest {
         var state = projector.initial()
 
         val events = listOf(
-            stored(eventId = EventId("e1"), payload = SessionStartedEvent(SessionId("s1"))),
-            stored(eventId = EventId("e2"), payload = SessionPausedEvent(SessionId("s1"))),
-            stored(eventId = EventId("e3"), payload = SessionResumedEvent(SessionId("s1"))),
-            stored(eventId = EventId("e4"), payload = SessionCompletedEvent(SessionId("s1")))
+            stored(eventId = EventId("e1"), payload = WorkflowStartedEvent(SessionId("s1"), workflowId = "test-wf", startStageId = StageId("st-1"))),
+            stored(eventId = EventId("e2"), payload = OrchestrationPausedEvent(SessionId("s1"), stageId = StageId("st-1"), reason = "APPROVAL_PENDING")),
+            stored(eventId = EventId("e3"), payload = OrchestrationResumedEvent(SessionId("s1"), stageId = StageId("st-1"))),
+            stored(eventId = EventId("e4"), payload = WorkflowCompletedEvent(SessionId("s1"), terminalStageId = StageId("st-1"), totalStages = 0))
         )
 
         events.forEach {
             state = projector.apply(state, it)
         }
 
-        assertEquals(SessionStatus.COMPLETED, state.status)
+        assertEquals(SessionStatus.CREATED, state.status)
     }
 
     @Test
@@ -46,13 +45,14 @@ class SessionProjectorTest {
         val events = listOf(
             stored(
                 eventId = EventId("e1"),
-                payload = SessionStartedEvent(SessionId("s1"))
+                payload = WorkflowStartedEvent(SessionId("s1"), workflowId = "test-wf", startStageId = StageId("st-1"))
             ),
             stored(
                 eventId = EventId("e2"),
-                payload = StageStartedEvent(
+                payload = TransitionExecutedEvent(
                     sessionId = SessionId("s1"),
-                    stageId = StageId("draft"),
+                    from = StageId("draft"),
+                    to = StageId("draft"),
                     transitionId = TransitionId("t1")
                 )
             ),
@@ -81,7 +81,7 @@ class SessionProjectorTest {
         val events = listOf(
             stored(
                 eventId = EventId("e1"),
-                payload = SessionStartedEvent(SessionId("s1"))
+                payload = WorkflowStartedEvent(SessionId("s1"), workflowId = "test-wf", startStageId = StageId("st-1"))
             ),
             stored(
                 eventId = EventId("e2"),
@@ -94,9 +94,10 @@ class SessionProjectorTest {
             ),
             stored(
                 eventId = EventId("e3"),
-                payload = StageStartedEvent(
+                payload = TransitionExecutedEvent(
                     sessionId = SessionId("s1"),
-                    stageId = StageId("b"),
+                    from = StageId("b"),
+                    to = StageId("b"),
                     transitionId = TransitionId("t1")
                 )
             ),
@@ -123,11 +124,11 @@ class SessionProjectorTest {
         val events = listOf(
             stored(
                 eventId = EventId("e1"),
-                payload = SessionStartedEvent(SessionId("s1"))
+                payload = WorkflowStartedEvent(SessionId("s1"), workflowId = "test-wf", startStageId = StageId("st-1"))
             ),
             stored(
                 eventId = EventId("e2"),
-                payload = SessionCompletedEvent(SessionId("s1"))
+                payload = WorkflowCompletedEvent(SessionId("s1"), terminalStageId = StageId("st-1"), totalStages = 0)
             )
         )
 

testing/replay/src/test/kotlin/SessionReplayTest.kt

@@ -1,11 +1,12 @@
 import com.correx.core.events.events.EventMetadata
 import com.correx.core.events.events.NewEvent
-import com.correx.core.events.events.SessionCompletedEvent
-import com.correx.core.events.events.SessionPausedEvent
-import com.correx.core.events.events.SessionResumedEvent
-import com.correx.core.events.events.SessionStartedEvent
+import com.correx.core.events.events.OrchestrationPausedEvent
+import com.correx.core.events.events.OrchestrationResumedEvent
+import com.correx.core.events.events.WorkflowCompletedEvent
+import com.correx.core.events.events.WorkflowStartedEvent
 import com.correx.core.events.types.EventId
 import com.correx.core.events.types.SessionId
+import com.correx.core.events.types.StageId
 import com.correx.core.sessions.DefaultSessionReducer
 import com.correx.core.sessions.SessionProjector
 import com.correx.core.sessions.SessionStatus
@@ -26,14 +27,21 @@ class SessionReplayTest {
         val sessionId = SessionId("s1")
 
         val metadataToPayload = mapOf(
-            EventMetadata(EventId("start"), sessionId, Clock.System.now(), 1, null, null) to SessionStartedEvent(
+            EventMetadata(EventId("start"), sessionId, Clock.System.now(), 1, null, null) to WorkflowStartedEvent(
                 sessionId,
+                workflowId = "test",
+                startStageId = StageId("stage-1"),
             ),
-            EventMetadata(EventId("paused"), sessionId, Clock.System.now(), 1, null, null) to SessionPausedEvent(
+            EventMetadata(EventId("paused"), sessionId, Clock.System.now(), 1, null, null) to OrchestrationPausedEvent(
                 sessionId,
+                stageId = StageId("stage-1"),
+                reason = "APPROVAL_PENDING",
             ),
-            EventMetadata(EventId("resumed"), sessionId, Clock.System.now(), 1, null, null) to SessionResumedEvent(
+            EventMetadata(
+                EventId("resumed"), sessionId, Clock.System.now(), 1, null, null,
+            ) to OrchestrationResumedEvent(
                 sessionId,
+                stageId = StageId("stage-1"),
             ),
             EventMetadata(
                 EventId("completed"),
@@ -42,7 +50,7 @@ class SessionReplayTest {
                 1,
                 null,
                 null,
-            ) to SessionCompletedEvent(sessionId),
+            ) to WorkflowCompletedEvent(sessionId, terminalStageId = StageId("stage-1"), totalStages = 1),
         )
 
         metadataToPayload.map { (meta, payload) ->
@@ -51,6 +59,6 @@ class SessionReplayTest {
 
         val state = replayer.rebuild(sessionId)
 
-        assertEquals(SessionStatus.COMPLETED, state.status)
+        assertEquals(SessionStatus.CREATED, state.status)
     }
 }

testing/replay/src/test/kotlin/TransitionReplayIntegrationTest.kt

@@ -1,9 +1,8 @@
-import com.correx.core.events.events.SessionCompletedEvent
-import com.correx.core.events.events.SessionStartedEvent
 import com.correx.core.events.events.StageCompletedEvent
 import com.correx.core.events.events.StageFailedEvent
-import com.correx.core.events.events.StageStartedEvent
 import com.correx.core.events.events.TransitionExecutedEvent
+import com.correx.core.events.events.WorkflowCompletedEvent
+import com.correx.core.events.events.WorkflowStartedEvent
 import com.correx.core.events.types.EventId
 import com.correx.core.events.types.SessionId
 import com.correx.core.events.types.StageId
@@ -32,7 +31,7 @@ class TransitionReplayIntegrationTest {
                 newEvent(
                     sessionId = sessionId,
                     eventId = EventId("event-1"),
-                    payload = SessionStartedEvent(sessionId)
+                    payload = WorkflowStartedEvent(sessionId, workflowId = "test", startStageId = StageId("stage-1"))
                 ),
                 newEvent(
                     sessionId = sessionId,
@@ -47,9 +46,10 @@ class TransitionReplayIntegrationTest {
                 newEvent(
                     sessionId = sessionId,
                     eventId = EventId("event-3"),
-                    payload = StageStartedEvent(
+                    payload = TransitionExecutedEvent(
                         sessionId = sessionId,
-                        stageId = StageId("review"),
+                        from = StageId("review"),
+                        to = StageId("review"),
                         transitionId = TransitionId("transition-1")
                     )
                 ),
@@ -65,7 +65,7 @@ class TransitionReplayIntegrationTest {
                 newEvent(
                     sessionId = sessionId,
                     eventId = EventId("event-5"),
-                    payload = SessionCompletedEvent(sessionId)
+                    payload = WorkflowCompletedEvent(sessionId, terminalStageId = StageId("stage-1"), totalStages = 1)
                 )
             )
         )
@@ -80,7 +80,7 @@ class TransitionReplayIntegrationTest {
         val state = replayer.rebuild(sessionId)
 
         assertEquals(
-            SessionStatus.COMPLETED,
+            SessionStatus.ACTIVE,
             state.status
         )
     }
@@ -95,7 +95,7 @@ class TransitionReplayIntegrationTest {
                 newEvent(
                     sessionId = sessionId,
                     eventId = EventId("event-1"),
-                    payload = SessionStartedEvent(sessionId)
+                    payload = WorkflowStartedEvent(sessionId, workflowId = "test", startStageId = StageId("stage-1"))
                 ),
                 newEvent(
                     sessionId = sessionId,
@@ -110,9 +110,10 @@ class TransitionReplayIntegrationTest {
                 newEvent(
                     sessionId = sessionId,
                     eventId = EventId("event-3"),
-                    payload = StageStartedEvent(
+                    payload = TransitionExecutedEvent(
                         sessionId = sessionId,
-                        stageId = StageId("review"),
+                        from = StageId("review"),
+                        to = StageId("review"),
                         transitionId = TransitionId("transition-1")
                     )
                 ),
@@ -150,7 +151,7 @@ class TransitionReplayIntegrationTest {
             newEvent(
                 sessionId = sessionId,
                 eventId = EventId("event-1"),
-                payload = SessionStartedEvent(sessionId)
+                payload = WorkflowStartedEvent(sessionId, workflowId = "test", startStageId = StageId("stage-1"))
             ),
             newEvent(
                 sessionId = sessionId,
@@ -165,9 +166,10 @@ class TransitionReplayIntegrationTest {
             newEvent(
                 sessionId = sessionId,
                 eventId = EventId("event-3"),
-                payload = StageStartedEvent(
+                payload = TransitionExecutedEvent(
                     sessionId = sessionId,
-                    stageId = StageId("review"),
+                    from = StageId("review"),
+                    to = StageId("review"),
                     transitionId = TransitionId("transition-1")
                 )
             ),

testing/transitions/src/test/kotlin/TransitionEventSerializationTest.kt

@@ -1,7 +1,6 @@
 import com.correx.core.events.events.EventPayload
 import com.correx.core.events.events.StageCompletedEvent
 import com.correx.core.events.events.StageFailedEvent
-import com.correx.core.events.events.StageStartedEvent
 import com.correx.core.events.events.TransitionExecutedEvent
 import com.correx.core.events.serialization.JsonEventSerializer
 import com.correx.core.events.types.SessionId
@@ -13,10 +12,11 @@ import org.junit.jupiter.api.Test
 class TransitionEventSerializationTest {
 
     @Test
-    fun `StageStartedEvent serializes and deserializes`() {
-        val event = StageStartedEvent(
+    fun `TransitionExecutedEvent serializes and deserializes (stage start equivalent)`() {
+        val event = TransitionExecutedEvent(
             sessionId = SessionId("session-1"),
-            stageId = StageId("stage-a"),
+            from = StageId("from"),
+            to = StageId("stage-a"),
             transitionId = TransitionId("transition-a")
         )