feat(kernel,server): rehydrate() + POST /sessions/{id}/resume

core/kernel/src/main/kotlin/com/correx/core/kernel/orchestration/DefaultSessionOrchestrator.kt

@@ -162,6 +162,22 @@ class DefaultSessionOrchestrator(
     fun validatedArtifactContent(sessionId: SessionId, artifactId: ArtifactId): String? =
         artifactContentCache["${sessionId.value}:${artifactId.value}"]
 
+    /**
+     * Rebuilds [artifactContentCache] from durable events after a server restart.
+     * Scans all events for [ArtifactValidatedEvent] and re-fetches the stored bytes
+     * from [artifactStore] for each one. Must be called before [resume] to ensure
+     * transition conditions that read artifact content work correctly.
+     */
+    suspend fun rehydrate(sessionId: SessionId) {
+        repositories.eventStore.readFrom(sessionId, fromSequence = 0L).forEach { event ->
+            val p = event.payload as? ArtifactValidatedEvent ?: return@forEach
+            val key = "${sessionId.value}:${p.artifactId.value}"
+            artifactStore.get(p.artifactId)
+                ?.toString(Charsets.UTF_8)
+                ?.let { artifactContentCache[key] = it }
+        }
+    }
+
     suspend fun resume(
         sessionId: SessionId,
         graph: WorkflowGraph,

core/kernel/src/main/kotlin/com/correx/core/kernel/orchestration/SessionOrchestrator.kt

@@ -134,7 +134,7 @@ private const val REPO_MAP_INJECT_TOP_K = 30
 abstract class SessionOrchestrator(
     repositories: OrchestratorRepositories,
     engines: OrchestratorEngines,
-    private val artifactStore: ArtifactStore,
+    protected val artifactStore: ArtifactStore,
     private val decisionJournalRepository: DefaultDecisionJournalRepository,
     private val decisionJournalRenderer: DecisionJournalRenderer = DecisionJournalRenderer(),
 ) {