Add system resource usage and availability to REST API process list

docs/http-api.md

@@ -180,6 +180,48 @@ curl -s http://127.0.0.1:9615/api/v1/processes
 
 An empty app set returns `[]` (never `null`).
 
+#### System resources usage and availability option
+
+To include host system resources usage and availability alongside the process list without breaking the default array format, pass a query parameter such as `?system=true` (or `?system_resources=true`, `?stats=true`, `?format=object`, `?include=system`):
+
+```sh
+curl -s "http://127.0.0.1:9615/api/v1/processes?system=true"
+```
+
+```json
+{
+  "processes": [
+    {
+      "pid": 7731,
+      "name": "web-0",
+      "pm_id": 0,
+      "monit": { "memory": 48896000, "cpu": 0.4 },
+      "pm2_env": { "name": "web-0", "status": "online", "pm_id": 0, "...": "..." }
+    }
+  ],
+  "system": {
+    "cpu_cores": 8,
+    "load_1": 0.15,
+    "load_5": 0.20,
+    "load_15": 0.18,
+    "total_memory": 17179869184,
+    "used_memory": 8589934592,
+    "available_memory": 8589934592,
+    "memory_used_pct": 50.0
+  },
+  "system_resources": {
+    "cpu_cores": 8,
+    "load_1": 0.15,
+    "load_5": 0.20,
+    "load_15": 0.18,
+    "total_memory": 17179869184,
+    "used_memory": 8589934592,
+    "available_memory": 8589934592,
+    "memory_used_pct": 50.0
+  }
+}
+```
+
 ### 5.3 `GET /api/v1/processes/{target}`
 
 Describe one app in full (same object shape as one element of the list). On an

internal/daemon/http.go

@@ -167,7 +167,10 @@ func (s *Server) httpHealth(w http.ResponseWriter, r *http.Request) {
 }
 
 // httpList returns every app as a PM2-compatible jlist array (the same JSON
-// `pm0 jlist` prints, via the shared renderer).
+// `pm0 jlist` prints, via the shared renderer). If requested via query param
+// (e.g. ?system=true, ?system_resources=true, ?stats=true, ?format=object,
+// or ?include=system), it returns an object containing the process list and
+// system resource usage and availability metrics.
 func (s *Server) httpList(w http.ResponseWriter, r *http.Request) {
 	resp, err := s.ListProcesses(r.Context(), &v1.ListProcessesRequest{})
 	if err != nil {
@@ -179,9 +182,39 @@ func (s *Server) httpList(w http.ResponseWriter, r *http.Request) {
 		writeErr(w, err)
 		return
 	}
+
+	if wantsSystemResources(r) {
+		sys := client.ReadSystemStats()
+		sysObj := map[string]any{
+			"cpu_cores":        sys.CPUCores,
+			"load_1":           sys.Load1,
+			"load_5":           sys.Load5,
+			"load_15":          sys.Load15,
+			"total_memory":     sys.TotalMem,
+			"used_memory":      sys.UsedMem,
+			"available_memory": sys.AvailMem,
+			"memory_used_pct":  sys.MemUsedPct,
+		}
+		writeJSON(w, http.StatusOK, map[string]any{
+			"processes":        json.RawMessage(b),
+			"system":           sysObj,
+			"system_resources": sysObj,
+		})
+		return
+	}
+
 	writeRawJSON(w, http.StatusOK, b)
 }
 
+func wantsSystemResources(r *http.Request) bool {
+	q := r.URL.Query()
+	return queryBool(q.Get("system"), false) ||
+		queryBool(q.Get("system_resources"), false) ||
+		queryBool(q.Get("stats"), false) ||
+		strings.EqualFold(q.Get("format"), "object") ||
+		strings.Contains(q.Get("include"), "system")
+}
+
 func (s *Server) httpDescribe(w http.ResponseWriter, r *http.Request) {
 	sel := selectorFromTarget(r.PathValue("target"))
 	resp, err := s.DescribeProcess(r.Context(), &v1.DescribeProcessRequest{Selector: sel})

internal/daemon/http_test.go

@@ -182,6 +182,34 @@ func TestHTTPProcessesEmptyIsArray(t *testing.T) {
 	}
 }
 
+func TestHTTPProcessesWithSystemResources(t *testing.T) {
+	_, _, ts := startHTTP(t)
+
+	params := []string{
+		"?system=true",
+		"?system_resources=true",
+		"?stats=true",
+		"?format=object",
+		"?include=system",
+	}
+
+	for _, param := range params {
+		code, body := httpGet(t, ts.URL+"/api/v1/processes"+param)
+		if code != http.StatusOK {
+			t.Fatalf("GET /api/v1/processes%s code = %d, want 200", param, code)
+		}
+		if !strings.Contains(body, `"processes":[]`) {
+			t.Fatalf("GET /api/v1/processes%s body = %s, want processes array", param, body)
+		}
+		if !strings.Contains(body, `"system":{`) || !strings.Contains(body, `"system_resources":{`) {
+			t.Fatalf("GET /api/v1/processes%s body = %s, want system/system_resources object", param, body)
+		}
+		if !strings.Contains(body, `"total_memory":`) || !strings.Contains(body, `"available_memory":`) || !strings.Contains(body, `"cpu_cores":`) {
+			t.Fatalf("GET /api/v1/processes%s body = %s, want memory and cpu fields", param, body)
+		}
+	}
+}
+
 func TestHTTPStartListDescribeActions(t *testing.T) {
 	_, c, ts := startHTTP(t)
 	name := harness.UniqueName("http")

pkg/client/table.go

@@ -297,7 +297,7 @@ func printUsageSummary(w io.Writer, ps []*v1.ProcessInfo, tableWidth int, color
 		}
 	}
 
-	sys := readSystemStats()
+	sys := ReadSystemStats()
 
 	// 1. Process summary
 	var procDisp string
@@ -699,18 +699,19 @@ func isTerminal(w io.Writer) bool {
 }
 
 type SystemStats struct {
-	TotalMem   uint64
-	UsedMem    uint64
-	MemUsedPct float64
-	CPUCores   int
-	Load1      float64
-	Load5      float64
-	Load15     float64
-	HasMem     bool
-	HasLoad    bool
+	TotalMem   uint64  `json:"total_memory"`
+	UsedMem    uint64  `json:"used_memory"`
+	AvailMem   uint64  `json:"available_memory"`
+	MemUsedPct float64 `json:"memory_used_pct"`
+	CPUCores   int     `json:"cpu_cores"`
+	Load1      float64 `json:"load_1"`
+	Load5      float64 `json:"load_5"`
+	Load15     float64 `json:"load_15"`
+	HasMem     bool    `json:"has_mem"`
+	HasLoad    bool    `json:"has_load"`
 }
 
-func readSystemStats() SystemStats {
+func ReadSystemStats() SystemStats {
 	stats := SystemStats{
 		CPUCores: runtime.NumCPU(),
 	}
@@ -728,15 +729,22 @@ func readSystemStats() SystemStats {
 	if data, err := os.ReadFile("/proc/meminfo"); err == nil {
 		lines := strings.Split(string(data), "\n")
 		var totalKB, availKB uint64
+		var foundTotal, foundAvail bool
 		for _, line := range lines {
 			if strings.HasPrefix(line, "MemTotal:") {
 				totalKB = parseMemKB(line)
+				foundTotal = true
 			} else if strings.HasPrefix(line, "MemAvailable:") {
 				availKB = parseMemKB(line)
+				foundAvail = true
+			}
+			if foundTotal && foundAvail {
+				break
 			}
 		}
 		if totalKB > 0 {
 			stats.TotalMem = totalKB * 1024
+			stats.AvailMem = availKB * 1024
 			if totalKB >= availKB {
 				stats.UsedMem = (totalKB - availKB) * 1024
 				stats.MemUsedPct = float64(totalKB-availKB) / float64(totalKB) * 100

pkg/client/table_test.go

@@ -144,7 +144,7 @@ func TestWriteListTableEmpty(t *testing.T) {
 }
 
 func TestReadSystemStats(t *testing.T) {
-	stats := readSystemStats()
+	stats := ReadSystemStats()
 	if stats.CPUCores <= 0 {
 		t.Errorf("expected CPUCores > 0, got %d", stats.CPUCores)
 	}