refactor(server,cli): shared payload-discriminator helper, single-read digest reuse, DOT label escaping

apps/cli/src/main/kotlin/com/correx/apps/cli/commands/EventsCommand.kt

@@ -44,14 +44,16 @@ fun renderEventRows(rows: List<EventRow>): String {
     return (listOf(header) + lines).joinToString("\n")
 }
 
+private fun String.dotEscape(): String = replace("\\", "\\\\").replace("\"", "\\\"")
+
 fun renderDot(rows: List<EventRow>): String = buildString {
     appendLine("digraph session {")
     rows.forEach { r ->
-        appendLine(""""${r.eventId}" [label="${r.type} #${r.sequence}"]""")
+        appendLine(""""${r.eventId.dotEscape()}" [label="${r.type.dotEscape()} #${r.sequence}"]""")
     }
     rows.forEach { r ->
         r.causationId?.let { causation ->
-            appendLine(""""${r.eventId}" -> "$causation"""")
+            appendLine(""""${r.eventId.dotEscape()}" -> "${causation.dotEscape()}"""")
         }
     }
     append("}")

apps/server/src/main/kotlin/com/correx/apps/server/replay/ReplayInspectionService.kt

@@ -15,12 +15,12 @@ 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.apps.server.serialization.payloadDiscriminator
+import com.correx.core.events.events.StoredEvent
 import com.correx.core.events.serialization.eventJson
 import com.correx.core.events.stores.EventStore
 import com.correx.core.events.types.SessionId
 import kotlinx.serialization.Serializable
-import kotlinx.serialization.json.jsonObject
-import kotlinx.serialization.json.jsonPrimitive
 import java.security.MessageDigest
 
 @Serializable
@@ -46,11 +46,12 @@ class ReplayInspectionService(private val eventStore: EventStore) {
         val events = eventStore.read(sessionId)
         val timeline = events.map { stored ->
             val element = eventJson.encodeToJsonElement(EventPayload.serializer(), stored.payload)
-            val type = element.jsonObject["type"]?.jsonPrimitive?.content ?: "unknown"
-            toTimelineEntry(stored.sequence, stored.payload, type)
+            toTimelineEntry(stored.sequence, stored.payload, payloadDiscriminator(element))
         }
-        val digest = computeDigest(sessionId)
-        val digest2 = computeDigest(sessionId)
+        val digest = computeDigest(events)
+        // Second digest from an independent store read — catches store-order or
+        // serialization nondeterminism; must NOT reuse the already-loaded list.
+        val digest2 = computeDigest(eventStore.read(sessionId))
         return ReplayReport(
             sessionId = sessionId.value,
             eventCount = events.size.toLong(),
@@ -79,12 +80,11 @@ class ReplayInspectionService(private val eventStore: EventStore) {
             else -> TimelineEntry(sequence, type, null, type)
         }
 
-    private fun computeDigest(sessionId: SessionId): String {
-        val events = eventStore.read(sessionId)
+    private fun computeDigest(events: List<StoredEvent>): String {
         val digest = MessageDigest.getInstance("SHA-256")
         for (event in events) {
             val element = eventJson.encodeToJsonElement(EventPayload.serializer(), event.payload)
-            val type = element.jsonObject["type"]?.jsonPrimitive?.content ?: "unknown"
+            val type = payloadDiscriminator(element)
             val payloadJsonString = eventJson.encodeToString(EventPayload.serializer(), event.payload)
             val line = "${event.sequence}|$type|$payloadJsonString"
             digest.update(line.toByteArray(Charsets.UTF_8))

apps/server/src/main/kotlin/com/correx/apps/server/routes/SessionRoutes.kt

@@ -3,6 +3,7 @@ package com.correx.apps.server.routes
 import com.correx.apps.server.ServerModule
 import com.correx.apps.server.protocol.SessionConfigDto
 import com.correx.apps.server.replay.ReplayInspectionService
+import com.correx.apps.server.serialization.payloadDiscriminator
 import com.correx.apps.server.ws.SessionStreamHandler
 import com.correx.core.events.events.EventPayload
 import com.correx.core.events.serialization.eventJson
@@ -18,8 +19,6 @@ import io.ktor.server.routing.route
 import io.ktor.server.websocket.webSocket
 import kotlinx.serialization.Serializable
 import kotlinx.serialization.json.JsonElement
-import kotlinx.serialization.json.JsonObject
-import kotlinx.serialization.json.jsonPrimitive
 import org.slf4j.LoggerFactory
 import java.util.*
 
@@ -164,7 +163,7 @@ private fun Route.getEventsRoute(module: ServerModule) {
             .asSequence()
             .map { stored ->
                 val payloadJson = eventJson.encodeToJsonElement(EventPayload.serializer(), stored.payload)
-                val type = (payloadJson as? JsonObject)?.get("type")?.jsonPrimitive?.content ?: "unknown"
+                val type = payloadDiscriminator(payloadJson)
                 EventRow(
                     sequence = stored.sequence,
                     eventId = stored.metadata.eventId.value,

apps/server/src/main/kotlin/com/correx/apps/server/serialization/PayloadDiscriminator.kt

@@ -0,0 +1,12 @@
+package com.correx.apps.server.serialization
+
+import kotlinx.serialization.json.JsonElement
+import kotlinx.serialization.json.JsonObject
+import kotlinx.serialization.json.jsonPrimitive
+
+const val UNKNOWN_PAYLOAD_TYPE = "unknown"
+
+// The polymorphic discriminator emitted by eventJson for every EventPayload —
+// payloads always encode to a JsonObject carrying a "type" key.
+fun payloadDiscriminator(element: JsonElement): String =
+    (element as? JsonObject)?.get("type")?.jsonPrimitive?.content ?: UNKNOWN_PAYLOAD_TYPE