feat(server,kernel): post-plan approval gate — operator reviews plan before lock

After a freestyle plan compiles successfully, requestPlanApproval is invoked
before ExecutionPlanLockedEvent is emitted. Rejection emits
ExecutionPlanRejectedEvent(source="operator") with no lock and no phase-2 run.
Adds public SessionOrchestrator.requestPlanApproval seam delegating to
requestStageApproval, wired in Main.kt. Two new tests cover the reject and
approve paths; existing tests stay green via the default passthrough param.

apps/server/src/main/kotlin/com/correx/apps/server/Main.kt

@@ -375,6 +375,7 @@ fun main() {
         planContent = { sid -> orchestrator.validatedArtifactContent(sid, ArtifactId("execution_plan")) },
         config = defaultOrchestrationConfig,
         runPhase2 = { sid, graph, cfg -> orchestrator.run(sid, graph, cfg) },
+        requestPlanApproval = { sid, planJson -> orchestrator.requestPlanApproval(sid, planJson) },
     )
     val module = ServerModule(
         orchestrator = orchestrator,

apps/server/src/main/kotlin/com/correx/apps/server/freestyle/FreestyleDriver.kt

@@ -29,6 +29,7 @@ class FreestyleDriver(
     private val planContent: (SessionId) -> String?,
     private val config: OrchestrationConfig,
     private val runPhase2: suspend (SessionId, WorkflowGraph, OrchestrationConfig) -> WorkflowResult,
+    private val requestPlanApproval: suspend (SessionId, String) -> Boolean = { _, _ -> true },
 ) {
     suspend fun lockAndRun(sessionId: SessionId) {
         val json = planContent(sessionId) ?: run {
@@ -42,6 +43,12 @@ class FreestyleDriver(
                 emitRejected(sessionId, "plan failed to compile: ${it.message}", "compile")
                 return
             }
+        val approved = requestPlanApproval(sessionId, json)
+        if (!approved) {
+            log.info("freestyle: execution plan rejected by operator for session={}", sessionId.value)
+            emitRejected(sessionId, "rejected by operator at plan review", "operator")
+            return
+        }
         eventStore.append(
             NewEvent(
                 metadata = EventMetadata(

apps/server/src/test/kotlin/com/correx/apps/server/freestyle/FreestyleDriverTest.kt

@@ -167,4 +167,78 @@ class FreestyleDriverTest {
         assertEquals(1, rejectedEvents.size, "Expected exactly one ExecutionPlanRejectedEvent")
         assertEquals("missing_content", rejectedEvents.single().source)
     }
+
+    @Test
+    fun `operator rejection at plan gate emits rejected and skips lock and phase2`(): Unit = runBlocking {
+        val sessionId = SessionId("driver-operator-reject-session")
+        val eventStore = InMemoryEventStore()
+        val registry = buildRegistry()
+        val compiler = ExecutionPlanCompiler(registry)
+
+        var runPhase2Invocations = 0
+
+        val driver = FreestyleDriver(
+            eventStore = eventStore,
+            compiler = compiler,
+            planContent = { validPlanJson },
+            config = OrchestrationConfig(),
+            runPhase2 = { _, _, _ ->
+                runPhase2Invocations++
+                WorkflowResult.Completed(sessionId, com.correx.core.events.types.StageId("done"))
+            },
+            requestPlanApproval = { _, _ -> false },
+        )
+
+        driver.lockAndRun(sessionId)
+
+        val lockedEvents = eventStore.read(sessionId)
+            .map { it.payload }
+            .filterIsInstance<ExecutionPlanLockedEvent>()
+
+        assertTrue(lockedEvents.isEmpty(), "No lock event expected when operator rejects")
+        assertEquals(0, runPhase2Invocations, "runPhase2 must not be called when operator rejects")
+
+        val rejectedEvents = eventStore.read(sessionId)
+            .map { it.payload }
+            .filterIsInstance<ExecutionPlanRejectedEvent>()
+        assertEquals(1, rejectedEvents.size, "Expected exactly one ExecutionPlanRejectedEvent")
+        assertEquals("operator", rejectedEvents.single().source)
+    }
+
+    @Test
+    fun `operator approval at plan gate locks and runs phase2`(): Unit = runBlocking {
+        val sessionId = SessionId("driver-operator-approve-session")
+        val eventStore = InMemoryEventStore()
+        val registry = buildRegistry()
+        val compiler = ExecutionPlanCompiler(registry)
+
+        var runPhase2Invocations = 0
+        var approvalPreview: String? = null
+
+        val driver = FreestyleDriver(
+            eventStore = eventStore,
+            compiler = compiler,
+            planContent = { validPlanJson },
+            config = OrchestrationConfig(),
+            runPhase2 = { sid, graph, _ ->
+                runPhase2Invocations++
+                WorkflowResult.Completed(sid, graph.start)
+            },
+            requestPlanApproval = { _, preview ->
+                approvalPreview = preview
+                assertTrue(preview.contains("stages"), "Preview should contain plan JSON with stages")
+                true
+            },
+        )
+
+        driver.lockAndRun(sessionId)
+
+        val lockedEvents = eventStore.read(sessionId)
+            .map { it.payload }
+            .filterIsInstance<ExecutionPlanLockedEvent>()
+
+        assertEquals(1, lockedEvents.size, "Expected exactly one ExecutionPlanLockedEvent after approval")
+        assertEquals(1, runPhase2Invocations, "runPhase2 should be called exactly once after approval")
+        assertTrue(approvalPreview != null, "requestPlanApproval should have been invoked")
+    }
 }