fix(apiserver): populate hosts-list slot usage counts

xcecli hosts list showed NUM_RUN/NUM_SSUSP/NUM_USUSP as always 0 --
the fields existed on HostInfo and were displayed, but nothing ever
assigned them. processHostData now derives per-host slot usage from
the live job store (exec_hosts + job_status), counting occupied slots
so the numbers are comparable to MAX_SLOT.

Partial fix for gitea#46 / bug-1743: the separate "dispatch stops at
8/16" question needs the reporter's live limits.yaml/pend-reason to
confirm a usergroup/queue slot limit, not addressed here.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Y4M5MJM2zK6nU43da267Ku

src/frontend/apiserver/controllers/host_control_test.go

@@ -137,3 +137,63 @@ func TestPreCheckHostControlRequest_CommentTooLong(t *testing.T) {
 		t.Error("expected error for comment exceeding 512 chars, got nil")
 	}
 }
+
+// TestProcessHostData_ComputesSlotUsageFromJobs is a regression guard for
+// bug-1743 (gitea #46): models.HostInfo.NumRun/.NumSSusp/.NumUSusp exist in
+// the schema and are already shown by `xcecli hosts list`, but nothing in
+// the apiserver ever assigned them -- they were permanently stuck at Go's
+// zero value, so `hosts list` always showed NUM_RUN=0 regardless of how many
+// jobs were actually running on a host. processHostData must now derive
+// these counts from store.Jobs' live exec_hosts/job_status data (the same
+// JSONB shape backend/convert_pure.go's job-conversion path populates:
+// {"host_slots":[{"host_name":..,"num_slots":N}],"num_hosts":N}), counting
+// slots (not just job count) so the numbers are comparable to max_slot.
+func TestProcessHostData_ComputesSlotUsageFromJobs(t *testing.T) {
+	resetHostControlState()
+
+	store.Hosts.Put("test01", models.HostInfo{
+		HostName: "test01",
+		NumCPUs:  16,
+		MaxSlot:  16,
+	})
+
+	putJob := func(id int64, execHosts string, status int) {
+		store.Jobs.Put(uint64(id), models.JobInfo{
+			Unique_JobID: id,
+			JobID:        id,
+			JobStatus:    status,
+			ExecHosts:    models.Jsonb{String: execHosts},
+		})
+	}
+
+	// 6 plain RUN jobs, 1 slot each on test01.
+	for i := int64(1); i <= 6; i++ {
+		putJob(i, `{"host_slots":[{"host_name":"test01","num_slots":1}],"num_hosts":1}`, models.JOBSTAT["RUN"])
+	}
+	// 1 user-suspended job (RUN|USUSP) -- must count as USUSP, not RUN.
+	putJob(7, `{"host_slots":[{"host_name":"test01","num_slots":1}],"num_hosts":1}`, models.JOBSTAT["RUN"]|models.JOBSTAT["USUSP"])
+	// 1 system-suspended job (RUN|SSUSP) using 2 slots on test01.
+	putJob(8, `{"host_slots":[{"host_name":"test01","num_slots":2}],"num_hosts":1}`, models.JOBSTAT["RUN"]|models.JOBSTAT["SSUSP"])
+	// 1 PEND job with no exec host yet -- must not be counted anywhere.
+	putJob(9, "", models.JOBSTAT["PEND"])
+	// 1 job on a different host -- must not count toward test01.
+	putJob(10, `{"host_slots":[{"host_name":"other-host","num_slots":1}],"num_hosts":1}`, models.JOBSTAT["RUN"])
+
+	rows := store.StoreToOrderMaps(store.Hosts)
+	result := processHostData(rows, "")
+
+	if result.Count != 1 {
+		t.Fatalf("expected 1 host row, got %d", result.Count)
+	}
+	row := result.Rows[0]
+
+	if got := row.Data["num_run"]; got != 6 {
+		t.Errorf("num_run = %v, want 6", got)
+	}
+	if got := row.Data["num_ssusp"]; got != 2 {
+		t.Errorf("num_ssusp = %v, want 2 (2-slot SSUSP job)", got)
+	}
+	if got := row.Data["num_ususp"]; got != 1 {
+		t.Errorf("num_ususp = %v, want 1", got)
+	}
+}

src/frontend/apiserver/controllers/hosts.go

@@ -8,6 +8,7 @@ import (
 	"apiserver/store"
 	"apiserver/utils"
 	logger "apiserver/utils"
+	"encoding/json"
 	"errors"
 	"reflect"
 	"strings"
@@ -565,7 +566,56 @@ func preCheckHostControlRequest(req *models.HostControlRequest) (bool, error) {
 	return isAll, nil
 }
 
+// hostSlotUsage holds counts of slots currently occupied on one host,
+// broken down by run/suspend sub-state, mirroring HostInfo.NumRun/
+// NumSSusp/NumUSusp.
+type hostSlotUsage struct {
+	Run, SSusp, USusp int
+}
+
+// execHostsJSON mirrors the JSONB shape backend/convert_pure.go's
+// buildJobInfoFromReplayJob() writes into JobInfo.ExecHosts.
+type execHostsJSON struct {
+	HostSlots []struct {
+		HostName string `json:"host_name"`
+		NumSlots int    `json:"num_slots"`
+	} `json:"host_slots"`
+}
+
+// computeHostSlotUsage derives per-host slot usage from the live job store,
+// since store.Hosts' own NumRun/NumSSusp/NumUSusp fields are never written
+// (bug-1743): a host's occupied-slot count can only be known by scanning
+// which non-terminal jobs are currently placed on it.
+func computeHostSlotUsage() map[string]hostSlotUsage {
+	usage := make(map[string]hostSlotUsage)
+	for _, job := range store.Jobs.List() {
+		if job.ExecHosts.String == "" {
+			continue
+		}
+		var parsed execHostsJSON
+		if err := json.Unmarshal([]byte(job.ExecHosts.String), &parsed); err != nil {
+			continue
+		}
+		for _, hs := range parsed.HostSlots {
+			u := usage[hs.HostName]
+			switch {
+			case job.JobStatus&models.JOBSTAT["USUSP"] != 0:
+				u.USusp += hs.NumSlots
+			case job.JobStatus&models.JOBSTAT["SSUSP"] != 0:
+				u.SSusp += hs.NumSlots
+			case job.JobStatus&models.JOBSTAT["RUN"] != 0:
+				u.Run += hs.NumSlots
+			default:
+				continue
+			}
+			usage[hs.HostName] = u
+		}
+	}
+	return usage
+}
+
 func processHostData(rows []utils.OrderMap, page_token string) utils.QueryResult {
+	slotUsage := computeHostSlotUsage()
 	for _, row := range rows {
 		if v, exist := row.Data["host_status"]; exist {
 			if v != nil {
@@ -574,6 +624,16 @@ func processHostData(rows []utils.OrderMap, page_token string) utils.QueryResult
 			}
 		}
 
+		// bug-1743: HostInfo.NumRun/.NumSSusp/.NumUSusp are never assigned
+		// anywhere else -- derive them here from the live job store so
+		// `hosts list` reflects actual slot usage instead of always 0.
+		if hostName, ok := row.Data["host_name"].(string); ok {
+			usage := slotUsage[hostName]
+			row.Data["num_run"] = usage.Run
+			row.Data["num_ssusp"] = usage.SSusp
+			row.Data["num_ususp"] = usage.USusp
+		}
+
 		// Process JSONB fields based on predefined list
 		for _, jsonbField := range models.JSONBHFields {
 			if v, exist := row.Data[jsonbField]; exist {