feat(scheduler-core): implement scheduler-side admin request handler (task 9.4)

Implements the scheduler's first request-reply opcode (OPCode_schedAdmin).
sched_handle_admin_request() (handler.c) decodes SchedAdminRequest and
dispatches by action: recordStatus answers synchronously (pure read);
recordStart/recordStop are deferred onto the existing pend_updates queue
(XCE_SCHED_OP_ADMIN_RECORD) since sched_record_start()'s snapshot call
requires the session_active==0 precondition only guaranteed on the driver
thread, not the async request-handling thread. driver.c's
xce_sched_driver_translate_pending_events() performs the deferred action
and sends the reply via a new xcecli_reply_schedadmin() (client.c/client.h),
correlated by seq copied before the original request is freed.

Adversarial review found a genuine cross-thread race: sched_record_status()
read driver-owned recording state (including a pointer the driver thread
frees) from the vtask thread with no lock -- the codebase's first such
race, missed by ASan (doesn't detect races). Fixed with a dedicated
record_lock scoped strictly to in-memory field access, never spanning file
I/O; sched_record_status() now strdup()s under the lock instead of
returning a borrowed live pointer. Verified with a real two-thread
lock-contention test (independently confirmed non-vacuous by removing the
lock and observing the test fail) plus a deterministic use-after-free
reproduction.

26/26 scheduler suite, clang-format clean.

src/scheduler/testsuite/test_job_array_expand.c

@@ -29,7 +29,20 @@
 
 int sched_init_config(xce_scheduler_t* s, xce_conf4sched_t* c)
 {
-    (void)s; (void)c; return 0;
+    (void)s;
+    (void)c;
+    return 0;
+}
+
+/* sched_record_status (recording.c, scheduler-core spec, task 9.4) --
+ * handler.c's OPCode_schedAdmin/recordStatus path references it; this file
+ * never exercises OPCode_schedAdmin, so a link-satisfying stub is enough,
+ * same rationale as sched_init_config above. */
+int sched_record_status(xce_scheduler_t* sched, sched_admin_reply_t* reply)
+{
+    (void)sched;
+    (void)reply;
+    return -EINVAL;
 }
 
 /* REAL kvmgr-backed job add/get -- same rtti path production uses (mirrors
@@ -84,7 +97,7 @@ static void fixture_init(xce_scheduler_t* sched)
 static void seed_existing_job(xce_scheduler_t* sched, uint64_t jobid)
 {
     xce_sched_job_t* job = (xce_sched_job_t*)calloc(1, sizeof(*job));
-    job->jobid            = jobid;
+    job->jobid           = jobid;
     sched_add_job(&(sched->core), job);
 }
 
@@ -99,9 +112,8 @@ static void seed_existing_job(xce_scheduler_t* sched, uint64_t jobid)
 static xce_job_submit_t* init_job_array(uint64_t base_jobid,
                                         uint64_t array_size)
 {
-    job_submit_data_t* submit
-        = (job_submit_data_t*)calloc(1, sizeof(*submit));
-    xce_job_submit_t*  ja = (xce_job_submit_t*)calloc(1, sizeof(*ja));
+    job_submit_data_t* submit = (job_submit_data_t*)calloc(1, sizeof(*submit));
+    xce_job_submit_t*  ja     = (xce_job_submit_t*)calloc(1, sizeof(*ja));
 
     submit->queue    = strdup("normal");
     submit->user     = strdup("tester");
@@ -145,12 +157,12 @@ static int pop_job_update(xce_scheduler_t* sched, xce_job_t*** jobs_out)
 
 static void test_job_array_push_expands_into_n_tasks(void)
 {
-    xce_scheduler_t    sched;
-    xce_job_submit_t*  ja;
-    dataset_t          dataset;
-    xce_job_t**        jobs = NULL;
-    int                njobs;
-    int                i;
+    xce_scheduler_t   sched;
+    xce_job_submit_t* ja;
+    dataset_t         dataset;
+    xce_job_t**       jobs = NULL;
+    int               njobs;
+    int               i;
 
     fixture_init(&sched);
     ja = init_job_array(5000, 3);
@@ -188,11 +200,11 @@ static void test_job_array_push_expands_into_n_tasks(void)
 
 static void test_job_array_redelivery_does_not_duplicate(void)
 {
-    xce_scheduler_t   sched;
-    dataset_t         dataset;
-    xce_job_t**       jobs = NULL;
-    int               njobs;
-    int               i;
+    xce_scheduler_t sched;
+    dataset_t       dataset;
+    xce_job_t**     jobs = NULL;
+    int             njobs;
+    int             i;
 
     fixture_init(&sched);
 
@@ -289,9 +301,9 @@ static void test_wire_dispatch_chain_delivers_n_tasks(void)
     xce_data_t        data;
     xce_request_t     request;
     xce_request_t     decoded;
-    io_packet_t      *pkt;
+    io_packet_t*      pkt;
     dataset_t         dataset;
-    xce_job_t       **jobs = NULL;
+    xce_job_t**       jobs = NULL;
     int               njobs;
     int               i;
 
@@ -319,12 +331,13 @@ static void test_wire_dispatch_chain_delivers_n_tasks(void)
     request.body_which   = Request_body_pushmsg;
     request.body.pushmsg = &data;
 
-    pkt = (io_packet_t *)calloc(1, sizeof(*pkt));
+    pkt = (io_packet_t*)calloc(1, sizeof(*pkt));
     TEST_ASSERT_NOT_NULL(pkt);
     TEST_ASSERT_EQUAL_INT(1, xce_encode(&request, pkt));
 
     memset(&decoded, 0, sizeof(decoded));
-    TEST_ASSERT_EQUAL_INT(0, xce_decode(pkt, &decoded)); /* consumes/frees pkt */
+    TEST_ASSERT_EQUAL_INT(0,
+                          xce_decode(pkt, &decoded)); /* consumes/frees pkt */
 
     /* Act 1: the REAL transport dispatcher (task 5.3b's fix) -- exactly what
      * vtask_entry() (xcectx.c) calls on every inbound push. */
@@ -364,7 +377,8 @@ static void test_wire_dispatch_chain_delivers_n_tasks(void)
 
 int main(int argc, char* argv[])
 {
-    (void)argc; (void)argv;
+    (void)argc;
+    (void)argv;
     UNITY_BEGIN();
     RUN_TEST(test_job_array_push_expands_into_n_tasks, 0);
     RUN_TEST(test_job_array_redelivery_does_not_duplicate, 0);