apiserver: derive array stats from live job store; fix CLI stats decode

type=array_stats (xce jobs list -A) read store.ArrayJobs, which has no
production writer, so it always answered zero rows. Stats are now derived
at query time by scanning store.Jobs and aggregating per array base ID
(controllers/arraystats.go), mirroring hosts.go's computeHostSlotUsage
precedent: counters can never drift from the element rows.

- GetJobsInfo/GetJobByIDs array_stats branches run the derived rows
  through the same ExecuteQuery filter/sort/paginate pipeline as store
  queries; unique_job_id rides in the field list so processJobData can
  annotate job_id_human (SelectFields drops unlisted fields).
- processJobData: new rowInt64 helper (uint64 bit-preserved + float64/
  json.Number tolerant) replaces brittle bare type assertions for
  unique_job_id/array_idx reads; dead code removed (StackLimit
  wrong-source copy, unreachable index error).
- QueryData(TableArrayJob) now returns a guard error instead of always
  answering zero rows from the never-written store.
- xcecli: ArrayJobStatsData got UnmarshalJSON via UnmarshalOrderMapRow —
  the server's OrderMap wrapper ({Fields,Data}) decoded to all-zero
  fields, which is why table mode showed 0/- rows against live arrays.
- analysis.md CL5 marked fixed with the real root cause.

Cluster-verified on t1/t2/t3: submit→PEND→RUN→DONE per element, kill
path, job_id filter, and per-status counters all live; all daemons
healthy. Unit suites: apiserver + xcecli green (CGO_ENABLED=0).

Co-Authored-By: Claude Code <noreply@anthropic.com>

src/frontend/apiserver/controllers/arraystats.go

@@ -0,0 +1,101 @@
+package controllers
+
+import (
+	"apiserver/backend"
+	"apiserver/models"
+	"apiserver/store"
+	"apiserver/utils"
+	"sort"
+)
+
+// Array statistics rows (type=array_stats, `xce jobs list -A`) are derived
+// from the live job store at query time, mirroring the bug-1743 pattern for
+// HostInfo.NumRun: store.ArrayJobs has no production writer (the controller's
+// array push and every single-job update land in store.Jobs only), so a
+// store-backed ArrayJobInfo would stay empty forever. Deriving per query keeps
+// a single source of truth -- the counters can never drift from the element
+// rows the other views show.
+//
+// The array identity (base job ID, name, user, queue, ...) comes from each
+// element's own fields; every element of an array carries the same submit spec
+// (the controller expands one shared descriptor), so the first element seen
+// for a base ID supplies them.
+
+// arrayAgg accumulates one array's counters while scanning store.Jobs.
+type arrayAgg struct {
+	info models.ArrayJobInfo
+}
+
+// deriveArrayJobStats scans store.Jobs and aggregates every array element row
+// into one models.ArrayJobInfo per array base job ID, sorted by job_id
+// (the stats view's default sort). Ordinary (non-array) jobs are skipped.
+func deriveArrayJobStats() []models.ArrayJobInfo {
+	aggs := make(map[int64]*arrayAgg)
+	for _, job := range store.Jobs.List() {
+		raw := uint64(job.Unique_JobID)
+		if !backend.IsArrayJob(raw) {
+			continue
+		}
+		base := int64(backend.ExtractArrayBaseID(raw))
+		agg, ok := aggs[base]
+		if !ok {
+			agg = &arrayAgg{info: models.ArrayJobInfo{
+				JobID:          base,
+				ArrayJobName:   job.JobName,
+				SubmitUser:     job.SubmitUser,
+				QueueName:      job.QueueName,
+				UserGroup:      job.UserGroup,
+				JobGroup:       job.JobGroup,
+				JobDescription: job.JobDescription,
+				JobName:        job.JobName,
+				ProjectName:    job.ProjectName,
+				LicenseProject: job.LicenseProject,
+				SLA:            job.SLA,
+			}}
+			aggs[base] = agg
+		}
+		agg.info.NumJobs++
+		// Classify through JobStateStr so the counters always agree with the
+		// status string every other view shows (suspend states are stored as
+		// RUN|USUSP / RUN|SSUSP / PEND|PSUSP combinations there).
+		switch models.JobStateStr(job.JobStatus) {
+		case "USUSP":
+			agg.info.NumUSusp++
+		case "SSUSP":
+			agg.info.NumSSusp++
+		case "PSUSP":
+			agg.info.NumPSusp++
+		case "RUN":
+			agg.info.NumRun++
+		case "PEND":
+			agg.info.NumPend++
+		case "EXIT":
+			agg.info.NumExit++
+		case "DONE":
+			agg.info.NumDone++
+		}
+	}
+
+	out := make([]models.ArrayJobInfo, 0, len(aggs))
+	for _, agg := range aggs {
+		out = append(out, agg.info)
+	}
+	sort.Slice(out, func(i, j int) bool { return out[i].JobID < out[j].JobID })
+	return out
+}
+
+// arrayStatsToOrderMaps converts derived stats rows to the OrderMap shape
+// QueryData hands to ExecuteQuery (mirrors store.StoreToOrderMaps).
+func arrayStatsToOrderMaps(rows []models.ArrayJobInfo) []utils.OrderMap {
+	result := make([]utils.OrderMap, 0, len(rows))
+	for _, row := range rows {
+		m := store.StructToOrderMap(row)
+		// unique_job_id = the base ID, so processJobData's job_id_human
+		// annotation (which reads unique_job_id) covers stats rows the same
+		// way it covers ordinary job rows: `jobs list -A` rows carry the
+		// dash-quad human ID every other view shows.
+		m.Data["unique_job_id"] = row.JobID
+		result = append(result, m)
+	}
+	return result
+}

src/frontend/apiserver/controllers/arraystats_test.go

@@ -0,0 +1,160 @@
+package controllers
+
+import (
+	"testing"
+
+	"apiserver/backend"
+	"apiserver/models"
+	"apiserver/store"
+	"apiserver/utils"
+
+	"go.uber.org/zap"
+)
+
+func init() {
+	utils.Log = zap.NewNop()
+}
+
+// Array statistics (type=array_stats, `xce jobs list -A`) are derived from
+// the live job store -- store.ArrayJobs has no production writer, so a
+// store-backed read always answered zero rows. These tests pin the derived
+// counters, identity fields and the human-ID annotation.
+
+// arrayStatsBase / arrayStatsBase2 are array-capable base IDs (tag 0, low 15
+// bits clear), as generateArrayJobID hands out.
+var arrayStatsBase = []uint64{
+	uint64(3)<<40 | uint64(1)<<20,
+	uint64(4)<<40 | uint64(1)<<20,
+}
+
+// mkArrayElement builds an array element row as the controller's push path
+// stores it: unique_job_id = MakeElementID(base, idx), job_id = base.
+func mkArrayElement(base uint64, idx int, status string) models.JobInfo {
+	uid := backend.MakeElementID(base, idx)
+	return models.JobInfo{
+		Unique_JobID: int64(uid),
+		JobID:        int64(base),
+		ArrayIdx:     idx,
+		JobStatus:    models.JOBSTAT[status],
+		JobName:      "arrv",
+		SubmitUser:   "alice",
+		QueueName:    "normal",
+	}
+}
+
+func TestDeriveArrayJobStats_CountsPerStatus(t *testing.T) {
+	store.InitStores()
+
+	// Array base[0]: 2 DONE, 1 RUN, 1 PEND.
+	for _, e := range []struct {
+		idx    int
+		status string
+	}{
+		{1, "DONE"}, {2, "DONE"}, {3, "RUN"}, {4, "PEND"},
+	} {
+		store.Jobs.Put(uint64(mkArrayElement(arrayStatsBase[0], e.idx, e.status).Unique_JobID),
+			mkArrayElement(arrayStatsBase[0], e.idx, e.status))
+	}
+	// Array base[1]: 1 EXIT.
+	store.Jobs.Put(uint64(mkArrayElement(arrayStatsBase[1], 1, "EXIT").Unique_JobID),
+		mkArrayElement(arrayStatsBase[1], 1, "EXIT"))
+	// An ordinary job must not appear in the stats.
+	store.Jobs.Put(999, models.JobInfo{Unique_JobID: 999, JobID: 999,
+		JobStatus: models.JOBSTAT["RUN"], JobName: "plain"})
+
+	rows := deriveArrayJobStats()
+	if len(rows) != 2 {
+		t.Fatalf("expected 2 array rows (ordinary job excluded), got %d: %+v", len(rows), rows)
+	}
+
+	first := rows[0]
+	if first.JobID != int64(arrayStatsBase[0]) {
+		t.Fatalf("rows sorted by job_id: first = %d, want %d", first.JobID, arrayStatsBase[0])
+	}
+	if first.NumJobs != 4 || first.NumDone != 2 || first.NumRun != 1 || first.NumPend != 1 {
+		t.Errorf("array base[0] counters: jobs=%d done=%d run=%d pend=%d, want 4/2/1/1",
+			first.NumJobs, first.NumDone, first.NumRun, first.NumPend)
+	}
+	second := rows[1]
+	if second.JobID != int64(arrayStatsBase[1]) || second.NumJobs != 1 || second.NumExit != 1 {
+		t.Errorf("array base[1] counters: jobs=%d exit=%d, want 1/1", second.NumJobs, second.NumExit)
+	}
+}
+
+func TestDeriveArrayJobStats_IdentityFromFirstElement(t *testing.T) {
+	store.InitStores()
+
+	e := mkArrayElement(arrayStatsBase[0], 2, "RUN")
+	e.UserGroup = "ug1"
+	e.ProjectName = "proj"
+	store.Jobs.Put(uint64(e.Unique_JobID), e)
+	// A later element with different identity fields must not win (elements
+	// of one array share the submit spec; first-seen supplies the identity).
+	e2 := mkArrayElement(arrayStatsBase[0], 1, "DONE")
+	e2.SubmitUser = "bob"
+	store.Jobs.Put(uint64(e2.Unique_JobID), e2)
+
+	rows := deriveArrayJobStats()
+	if len(rows) != 1 {
+		t.Fatalf("expected 1 array row, got %d", len(rows))
+	}
+	got := rows[0]
+	if got.SubmitUser != "alice" || got.UserGroup != "ug1" || got.ProjectName != "proj" {
+		t.Errorf("identity fields: user=%q ug=%q proj=%q, want alice/ug1/proj",
+			got.SubmitUser, got.UserGroup, got.ProjectName)
+	}
+}
+
+func TestDeriveArrayJobStats_SuspendSubStates(t *testing.T) {
+	store.InitStores()
+
+	for _, e := range []struct {
+		idx    int
+		status int
+	}{
+		// Suspend states are stored as RUN|USUSP / PEND|PSUSP
+		// combinations (JobStateStr's classification; the controller
+		// ORs the suspend bit onto the base state). SSUSP currently has
+		// no producer, so it is covered by the USUSP case symmetrically.
+		{1, models.JOBSTAT["RUN"] | models.JOBSTAT["USUSP"]},
+		{2, models.JOBSTAT["RUN"] | models.JOBSTAT["SSUSP"]},
+	} {
+		ele := mkArrayElement(arrayStatsBase[0], e.idx, "RUN")
+		ele.JobStatus = e.status
+		store.Jobs.Put(uint64(ele.Unique_JobID), ele)
+	}
+	psusp := mkArrayElement(arrayStatsBase[0], 3, "PEND")
+	psusp.JobStatus = models.JOBSTAT["PEND"] | models.JOBSTAT["PSUSP"]
+	store.Jobs.Put(uint64(psusp.Unique_JobID), psusp)
+
+	rows := deriveArrayJobStats()
+	if len(rows) != 1 {
+		t.Fatalf("expected 1 array row, got %d", len(rows))
+	}
+	got := rows[0]
+	if got.NumJobs != 3 || got.NumSSusp != 1 || got.NumUSusp != 1 || got.NumPSusp != 1 ||
+		got.NumRun != 0 || got.NumPend != 0 {
+		t.Errorf("suspend counters: jobs=%d ssusp=%d ususp=%d psusp=%d run=%d pend=%d",
+			got.NumJobs, got.NumSSusp, got.NumUSusp, got.NumPSusp, got.NumRun, got.NumPend)
+	}
+}
+
+func TestArrayStatsToOrderMaps_AnnotatesHumanID(t *testing.T) {
+	stats := []models.ArrayJobInfo{{JobID: int64(arrayStatsBase[0]), NumJobs: 2, NumDone: 2}}
+	rows := arrayStatsToOrderMaps(stats)
+	if len(rows) != 1 {
+		t.Fatalf("expected 1 row, got %d", len(rows))
+	}
+	// The conversion carries unique_job_id (the array base ID); processJobData
+	// turns it into job_id_human at the HTTP layer, mirroring element rows.
+	got, ok := rows[0].Data["unique_job_id"]
+	if !ok {
+		t.Fatal("unique_job_id missing from stats row")
+	}
+	if got != int64(arrayStatsBase[0]) {
+		t.Errorf("unique_job_id = %v, want %d", got, arrayStatsBase[0])
+	}
+	if got, _ := rows[0].Data["num_jobs"].(int); got != 2 {
+		t.Errorf("num_jobs = %v, want 2", rows[0].Data["num_jobs"])
+	}
+}

src/frontend/apiserver/controllers/jobs.go

@@ -325,7 +325,10 @@ func (j JobController) GetJobsInfo(ctx *gin.Context) {
 	// ---- check fields ----
 	// get fields and do check, if not set, use default display columns
 	if typeValue == "array_stats" {
-		fields = models.ARRAY_JOB_DEFAULT_COLUMN
+		// unique_job_id must ride along in the field list: ExecuteQuery's
+		// SelectFields drops anything not requested, and processJobData
+		// annotates job_id_human from it.
+		fields = append(append([]string{}, models.ARRAY_JOB_DEFAULT_COLUMN...), "unique_job_id")
 	} else {
 		if fieldsStr != "" {
 			fields = utils.ParseFields(fieldsStr)
@@ -478,7 +481,13 @@ func (j JobController) GetJobsInfo(ctx *gin.Context) {
 	var jqueryReply []utils.OrderMap // Declare jqueryReply
 	pagetoken := ""                  // Initialize pagetoken with an empty string or appropriate value
 	if typeValue == "array_stats" {
-		jqueryReply, pagetoken, err = services.QueryData(services.TableArrayJob, queryOpts, fields)
+		// Stats rows are derived from the live job store (arraystats.go):
+		// store.ArrayJobs has no production writer, so the query used to
+		// always answer zero rows (`xce jobs list -A` → "no job found").
+		jqueryReply = arrayStatsToOrderMaps(deriveArrayJobStats())
+		// Pagination over derived rows: run the same filter → sort →
+		// paginate → select pipeline the store path would.
+		jqueryReply, pagetoken = store.ExecuteQuery(jqueryReply, queryOpts, fields)
 	} else {
 		jqueryReply, pagetoken, err = services.QueryData(services.TableJobInfo, queryOpts, fields)
 	}
@@ -684,7 +693,8 @@ func (j JobController) GetJobByIDs(ctx *gin.Context) {
 
 		var fields []string
 		if typeValue == "array_stats" {
-			fields = models.ARRAY_JOB_DEFAULT_COLUMN
+			// same unique_job_id requirement as GetJobsInfo's array_stats path
+			fields = append(append([]string{}, models.ARRAY_JOB_DEFAULT_COLUMN...), "unique_job_id")
 		} else {
 			if fieldsStr != "" {
 				fields = utils.ParseFields(fieldsStr)
@@ -765,7 +775,11 @@ func (j JobController) GetJobByIDs(ctx *gin.Context) {
 			var jqueryReply []utils.OrderMap // Declare jqueryReply
 
 			if typeValue == "array_stats" {
-				jqueryReply, page_token, err = services.QueryData(services.TableArrayJob, queryOpts, fields)
+				// Stats rows are derived from the live job store
+				// (arraystats.go): store.ArrayJobs has no production writer,
+				// so the query used to always answer zero rows.
+				jqueryReply = arrayStatsToOrderMaps(deriveArrayJobStats())
+				jqueryReply, page_token = store.ExecuteQuery(jqueryReply, queryOpts, fields)
 			} else {
 				jqueryReply, page_token, err = services.QueryData(services.TableJobInfo, queryOpts, fields)
 			}
@@ -1531,9 +1545,6 @@ func preCheckJobRequest(req *models.JobSubmitRequest) (n int, isArray bool, err
 	if req.ShellLimit.DataLimit.MB != 0 {
 		req.DataLimit = req.ShellLimit.DataLimit
 	}
-	if req.ShellLimit.StackLimit.MB != 0 {
-		req.StackLimit = req.ShellLimit.DataLimit
-	}
 	if req.ShellLimit.StackLimit.MB != 0 {
 		req.StackLimit = req.ShellLimit.StackLimit
 	}
@@ -1844,9 +1855,6 @@ func createArrayName(jobName string) (arrayName string, indices []int, slimit in
 					if err != nil || index < 1 {
 						return "", nil, -1, fmt.Errorf("index must be a positive integer")
 					}
-					if err != nil {
-						return "", nil, -1, fmt.Errorf("invalid index value: %s", part)
-					}
 					if _, exists := seenIndices[index]; !exists {
 						seenIndices[index] = struct{}{}
 						indices = append(indices, index)
@@ -3015,12 +3023,23 @@ func normalizeJobStatus(v any) (int, bool) {
 // produces as int, panicking every control request into an HTTP 500 before it
 // reached the controller.
 func jobArrayIdx(row utils.OrderMap) int {
-	if v, ok := row.Data["array_idx"]; ok {
-		if n, ok := normalizeJobInt64(v); ok {
-			return int(n)
-		}
+	n, _ := rowInt64(row, "array_idx")
+	return int(n)
+}
+
+// rowInt64 reads an integer column of a store row as int64, tolerating every
+// numeric representation the store or a JSON decode path produces (int,
+// int32, int64, float64, json.Number; uint64 bit-pattern preserved, as
+// rowUint64 does). Returns ok=false when the column is absent or not numeric.
+func rowInt64(row utils.OrderMap, col string) (int64, bool) {
+	v, ok := row.Data[col]
+	if !ok {
+		return 0, false
 	}
-	return 0
+	if u, isUint64 := v.(uint64); isUint64 {
+		return int64(u), true
+	}
+	return normalizeJobInt64(v)
 }
 
 func processJobData(rows []utils.OrderMap, pagetoken string) utils.QueryResult {
@@ -3031,21 +3050,13 @@ func processJobData(rows []utils.OrderMap, pagetoken string) utils.QueryResult {
 		// format, which parses only that form. Data correctness lives here,
 		// not in the clients. FormatJobID is the apiserver's own C fmt_jobid
 		// equivalent (backend.FormatJobID).
-		if uid, exist := row.Data["unique_job_id"]; exist {
-			var jobID int64
-			switch v := uid.(type) {
-			case int64:
-				jobID = v
-			case int:
-				jobID = int64(v)
-			case int32:
-				jobID = int64(v)
-			case float64:
-				jobID = int64(v)
-			}
-			if jobID != 0 {
-				row.Data["job_id_human"] = backend.FormatJobID(jobID)
-			}
+		if jobID, ok := rowInt64(row, "unique_job_id"); ok && jobID != 0 {
+			// Human-readable job ID (cluster-apiserver-timestamp-seq) so
+			// clients (MCP server, CLI) can cross-reference with the
+			// xce_test/xcecli dash format, which parses only that form. Data
+			// correctness lives here, not in the clients. FormatJobID is the
+			// apiserver's own C fmt_jobid equivalent (backend.FormatJobID).
+			row.Data["job_id_human"] = backend.FormatJobID(jobID)
 		}
 
 		if v, exist := row.Data["job_status"]; exist {
@@ -3059,16 +3070,16 @@ func processJobData(rows []utils.OrderMap, pagetoken string) utils.QueryResult {
 		if jobName, exist := row.Data["job_name"]; exist {
 			// Use IsArrayJob to detect array children, which covers
 			// the first child (idx=0) that the old array_idx > 0 check missed.
-			var isArray bool
-			if uid, ok := row.Data["unique_job_id"].(int64); ok {
+			// The ID read goes through the tolerant rowInt64 (bug-1490's
+			// lesson: a bare .(int64) assertion silently skips the row when
+			// the store or a JSON decode path produced another numeric
+			// representation).
+			isArray := false
+			if uid, ok := rowInt64(row, "unique_job_id"); ok {
 				isArray = backend.IsArrayJob(uint64(uid))
 			}
 			if isArray {
-				if arrayIdx, ok := row.Data["array_idx"].(int); ok {
-					row.Data["job_name"] = fmt.Sprintf("%s[%d]", jobName, arrayIdx)
-				} else if arrayIdx64, ok := row.Data["array_idx"].(int64); ok {
-					row.Data["job_name"] = fmt.Sprintf("%s[%d]", jobName, arrayIdx64)
-				}
+				row.Data["job_name"] = fmt.Sprintf("%s[%d]", jobName, jobArrayIdx(row))
 			} else {
 				row.Data["job_name"] = jobName
 			}

src/frontend/apiserver/controllers/jobs_handler_test.go

@@ -973,6 +973,111 @@ func assert400(t *testing.T, name string, w *httptest.ResponseRecorder, want str
 	}
 }
 
+// arrayStatsRows decodes the rows of a type=array_stats list reply.
+func arrayStatsRows(t *testing.T, w *httptest.ResponseRecorder) []map[string]interface{} {
+	t.Helper()
+	if w.Code != http.StatusOK {
+		t.Fatalf("status = %d, want 200; body: %s", w.Code, w.Body.String())
+	}
+	dec := json.NewDecoder(bytes.NewReader(w.Body.Bytes()))
+	dec.UseNumber()
+	var raw struct {
+		Data struct {
+			Count int `json:"count"`
+			Rows  []struct {
+				Data map[string]interface{} `json:"Data"`
+			} `json:"rows"`
+		} `json:"data"`
+	}
+	if err := dec.Decode(&raw); err != nil {
+		t.Fatalf("decode array_stats reply: %v; body: %s", err, w.Body.String())
+	}
+	rows := make([]map[string]interface{}, 0, len(raw.Data.Rows))
+	for _, r := range raw.Data.Rows {
+		rows = append(rows, r.Data)
+	}
+	if raw.Data.Count != len(rows) {
+		t.Errorf("count = %d, rows = %d", raw.Data.Count, len(rows))
+	}
+	return rows
+}
+
+// TestJobHandler_ArrayStatsDerivedFromJobStore covers `xce jobs list -A`
+// (type=array_stats): rows are derived from the live job store, one per
+// array, with counters matching the elements' states and a job_id_human
+// annotation (store.ArrayJobs has no production writer).
+func TestJobHandler_ArrayStatsDerivedFromJobStore(t *testing.T) {
+	f := newHandlerFixture(t)
+	s := seedQueryJobs(f)
+	x, y := s.X, s.Y
+	X := backend.FormatJobID(int64(x))
+
+	// Move element 2 of X to DONE so its counters must shift accordingly
+	// (seedArrayElements stored all four as RUN).
+	elem2 := backend.MakeElementID(x, 2)
+	got, _ := store.Jobs.Get(elem2)
+	got.JobStatus = models.JOBSTAT["DONE"]
+	store.Jobs.Put(elem2, got)
+
+	// GetJobsInfo?type=array_stats lists every seeded array with counters.
+	w := f.do(http.MethodGet, "/xce/v1/jobs?type=array_stats", nil)
+	rows := arrayStatsRows(t, w)
+	if len(rows) != 4 {
+		t.Fatalf("array_stats rows = %d, want 4 (arrays X, Y, Z, W)", len(rows))
+	}
+
+	byJobID := map[uint64]map[string]interface{}{}
+	for _, row := range rows {
+		n, ok := row["job_id"].(json.Number)
+		if !ok {
+			t.Fatalf("stats row without job_id: %v", row)
+		}
+		id, _ := strconv.ParseUint(n.String(), 10, 64)
+		byJobID[id] = row
+	}
+
+	xRow := byJobID[x]
+	if xRow == nil {
+		t.Fatalf("array X missing from stats: %v", rows)
+	}
+	// X has elements 1,2,3,4: 3 RUN + 1 DONE after the overwrite.
+	for field, want := range map[string]float64{
+		"num_jobs": 4, "num_run": 3, "num_done": 1,
+		"num_pend": 0, "num_exit": 0,
+	} {
+		n, _ := xRow[field].(json.Number)
+		if got, _ := n.Float64(); got != want {
+			t.Errorf("X.%s = %v, want %v", field, n.String(), want)
+		}
+	}
+	if human, _ := xRow["job_id_human"].(string); human != X {
+		t.Errorf("X.job_id_human = %q, want %q", human, X)
+	}
+
+	yRow := byJobID[y]
+	if yRow == nil {
+		t.Fatalf("array Y missing from stats: %v", rows)
+	}
+	if n, _ := yRow["num_jobs"].(json.Number); n.String() != "2" {
+		t.Errorf("Y.num_jobs = %v, want 2", yRow["num_jobs"])
+	}
+
+	// job_id filter (the ARRAY_JOB_SUPPORT_FILTERS path) narrows to one row.
+	w = f.do(http.MethodGet, "/xce/v1/jobs?type=array_stats&filter="+
+		url.QueryEscape("{job_id:eq:"+X+"}"), nil)
+	rows = arrayStatsRows(t, w)
+	if len(rows) != 1 {
+		t.Fatalf("filtered array_stats rows = %d, want 1", len(rows))
+	}
+
+	// GetJobByIDs?type=array_stats answers the same derived row.
+	w = f.do(http.MethodGet, "/xce/v1/jobs/"+url.PathEscape(X)+"?type=array_stats", nil)
+	rows = arrayStatsRows(t, w)
+	if len(rows) != 1 {
+		t.Fatalf("GetJobByIDs array_stats rows = %d, want 1; body: %s", len(rows), w.Body.String())
+	}
+}
+
 // TestJobHandler_QuerySelections covers the GetJobsInfo rows of the design's
 // Testing Strategy (Query).
 func TestJobHandler_QuerySelections(t *testing.T) {

src/frontend/apiserver/controllers/processjobdata_test.go

@@ -3,6 +3,7 @@ package controllers
 import (
 	"testing"
 
+	"apiserver/backend"
 	"apiserver/utils"
 
 	"go.uber.org/zap"
@@ -55,3 +56,66 @@ func TestProcessJobData_NoJobIDHumanWhenZero(t *testing.T) {
 		t.Error("job_id_human should not be set for zero job id")
 	}
 }
+
+// The array-child [idx] name annotation must survive every numeric
+// representation a store row or JSON decode path can produce. The old code
+// asserted .(int64)/.(int) and silently left the suffix off for anything
+// else (bug-1490's lesson, this time as a silent wrong value).
+func TestProcessJobData_ArrayNameSuffix_NumericRepresentations(t *testing.T) {
+	// 1-0-1786585485-0[2]: an array-capable base with the array tag and
+	// index 2 packed in, as backend.MakeElementID composes it.
+	uid := int64(backend.MakeElementID(uint64(1)<<40|uint64(1)<<20, 2))
+
+	for name, tc := range map[string]struct {
+		uid any
+		idx any
+	}{
+		"int64/int":     {uid, int(2)},
+		"int64/int64":   {uid, int64(2)},
+		"float64/int":   {float64(uid), int(2)},
+		"float64/int64": {float64(uid), int64(2)},
+		"float64/float": {float64(uid), float64(2)},
+	} {
+		rows := []utils.OrderMap{
+			{
+				Fields: []string{"unique_job_id", "job_name"},
+				Data: map[string]interface{}{
+					"unique_job_id": tc.uid,
+					"job_name":      "arrv",
+				},
+			},
+		}
+		// array_idx rides the row when present (store path) and defaults to
+		// jobArrayIdx's 0 when absent (some JSON decode paths).
+		rows[0].Data["array_idx"] = tc.idx
+		res := processJobData(rows, "")
+		if got, _ := res.Rows[0].Data["job_name"].(string); got != "arrv[2]" {
+			t.Errorf("%s: job_name = %q, want arrv[2]", name, got)
+		}
+	}
+}
+
+// uint64 unique_job_id (a representation rowUint64 handles elsewhere) must
+// still be recognized as an array child and formatted as a human ID.
+func TestProcessJobData_Uint64UniqueJobID(t *testing.T) {
+	uid := backend.MakeElementID(uint64(1)<<40|uint64(1)<<20, 3)
+	rows := []utils.OrderMap{
+		{
+			Fields: []string{"unique_job_id", "job_name", "array_idx"},
+			Data: map[string]interface{}{
+				"unique_job_id": uid,
+				"job_name":      "arrv",
+				"array_idx":     uint64(3),
+			},
+		},
+	}
+	res := processJobData(rows, "")
+	row := res.Rows[0]
+	if got, _ := row.Data["job_name"].(string); got != "arrv[3]" {
+		t.Errorf("job_name = %v, want arrv[3]", row.Data["job_name"])
+	}
+	want := backend.FormatJobID(int64(uid))
+	if got, _ := row.Data["job_id_human"].(string); got != want {
+		t.Errorf("job_id_human = %v, want %v", row.Data["job_id_human"], want)
+	}
+}

src/frontend/apiserver/services/data_service.go

@@ -40,7 +40,11 @@ func QueryData(tableName string, queryOpts *utils.QueryOptions, fields []string)
 	case TableClusterInfo:
 		rows = store.StoreToOrderMaps(store.Clusters)
 	case TableArrayJob:
-		rows = store.StoreToOrderMaps(store.ArrayJobs)
+		// Array stats (type=array_stats) are derived from the live job store
+		// by the controllers package (arraystats.go) -- store.ArrayJobs has
+		// no production writer, so reading it here always answered zero rows.
+		// This case stays reachable only if a future caller forgets that.
+		return nil, "", fmt.Errorf("array stats are derived by the caller; QueryData(TableArrayJob) is not supported")
 	case TableJobExecHosts:
 		rows = store.StoreToOrderMaps(store.JobExecHosts)
 	case TableRolePermission:

src/frontend/docs/analysis.md

@@ -152,7 +152,7 @@ None of these exist in the current codebase. The Swagger UI will show completely
 | **CL2** | TLS verification disabled | `request.go` `SetRootCAs` | `InsecureSkipVerify: true` always set; `loadRootCAs` is defined but never called |
 | **CL3** | Token header space inconsistency | `request.go` | `SubmitJob` uses `" "+token`; all other methods use `""+token` |
 | **CL4** | No retry on transient errors | `request.go` | Single attempt; network blips cause immediate failure |
-| **CL5** | `xce jobs` array stats has no display | `cmd/jobs/list.go` | `?type=array_stats` is sent but output formatter doesn't handle `ArrayJobStatsData` |
+| **CL5** | ~~`xce jobs` array stats has no display~~ **FIXED** | `cmd/jobs/list.go` | Display path exists (`ArrayJobsPagePrinter`); the real gap was server-side — `?type=array_stats` read `store.ArrayJobs` which has no writer and always answered zero rows. Stats are now derived from the live job store (controllers/arraystats.go). |
 
 ---
 

src/frontend/xcecli/models/jobs.go

@@ -507,6 +507,19 @@ type ArrayJobStatsData struct {
 	NumPSusp     int    `json:"num_psusp"`
 }
 
+// UnmarshalJSON decodes both the OrderMap wire format the server sends for
+// store-backed rows ({"Fields":[...],"Data":{...}}) and a bare object, so
+// array_stats replies decode past the wrapper instead of landing all-zero.
+func (s *ArrayJobStatsData) UnmarshalJSON(data []byte) error {
+	type alias ArrayJobStatsData
+	var a alias
+	if err := UnmarshalOrderMapRow(data, &a); err != nil {
+		return err
+	}
+	*s = ArrayJobStatsData(a)
+	return nil
+}
+
 // job array statistics response data structure
 type ArrayJobsStatsResponse struct {
 	Code int    `json:"code"`

src/frontend/xcecli/models/jobs_test.go

@@ -93,3 +93,35 @@ func TestPendingReasonUnmarshalUnknownObject(t *testing.T) {
 		t.Fatalf("unknown object: want raw fallback, got %q", string(p))
 	}
 }
+
+func TestArrayJobStatsData_UnmarshalOrderMapWrapper(t *testing.T) {
+	// The server sends store rows as OrderMap wrappers; without the custom
+	// UnmarshalJSON every stats field decoded to zero (CL5's "no display"
+	// symptom: xce jobs list -A showed 0/- rows against live arrays).
+	row := `{"Fields":["job_id","array_job_name","submit_user","num_jobs"],
+	         "Data":{"job_id":73937137023582208,
+	                 "array_job_name":"arrv",
+	                 "submit_user":"alice",
+	                 "num_jobs":4,
+	                 "num_done":1,
+	                 "num_run":3}}`
+	var s ArrayJobStatsData
+	if err := json.Unmarshal([]byte(row), &s); err != nil {
+		t.Fatalf("ArrayJobStatsData unmarshal: %v", err)
+	}
+	if s.JobID != 73937137023582208 || s.ArrayJobName != "arrv" || s.SubmitUser != "alice" ||
+		s.NumJobs != 4 || s.NumDone != 1 || s.NumRun != 3 {
+		t.Fatalf("decoded stats: %+v", s)
+	}
+}
+
+func TestArrayJobStatsData_UnmarshalBareObject(t *testing.T) {
+	// Bare objects (no wrapper) must keep decoding as before.
+	var s ArrayJobStatsData
+	if err := json.Unmarshal([]byte(`{"job_id":7,"num_pend":2}`), &s); err != nil {
+		t.Fatalf("bare object unmarshal: %v", err)
+	}
+	if s.JobID != 7 || s.NumPend != 2 {
+		t.Fatalf("decoded stats: %+v", s)
+	}
+}