feat(server): step usage counts endpoint

server/internal/api/workflows.go

@@ -23,6 +23,7 @@ func registerWorkflowRoutes(g *gin.RouterGroup) {
 	g.GET("/steps/:id/export", exportStep)
 	g.POST("/steps/import", importStep)
 	g.POST("/steps/seed-defaults", seedDefaults)
+	g.GET("/steps/usage", stepUsage)
 	g.POST("/steps/parse", parseStep)
 
 	g.GET("/workflows", listWorkflows)
@@ -154,6 +155,15 @@ func listSteps(c *gin.Context) {
 	c.JSON(http.StatusOK, steps)
 }
 
+func stepUsage(c *gin.Context) {
+	counts, err := services.StepUsageCounts()
+	if err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+	c.JSON(http.StatusOK, counts)
+}
+
 func createStep(c *gin.Context) {
 	var s models.WorkflowStep
 	if err := c.ShouldBindJSON(&s); err != nil {

server/internal/services/workflows.go

@@ -61,6 +61,34 @@ func ListSteps() ([]models.WorkflowStep, error) {
 	return steps, nil
 }
 
+// StepUsageCounts returns, per library step_id, the number of distinct
+// workflows that reference it. Inline steps have no step_id and are ignored.
+func StepUsageCounts() (map[string]int, error) {
+	ctx, cancel := wfCtx()
+	defer cancel()
+	cur, err := db.Col("workflows").Find(ctx, bson.M{})
+	if err != nil {
+		return nil, err
+	}
+	defer cur.Close(ctx)
+	var wfs []models.Workflow
+	if err := cur.All(ctx, &wfs); err != nil {
+		return nil, err
+	}
+	counts := map[string]int{}
+	for _, w := range wfs {
+		seen := map[string]bool{}
+		for _, ref := range w.Steps {
+			if ref.StepID == "" || seen[ref.StepID] {
+				continue
+			}
+			seen[ref.StepID] = true
+			counts[ref.StepID]++
+		}
+	}
+	return counts, nil
+}
+
 func CreateStep(s models.WorkflowStep) (*models.WorkflowStep, error) {
 	ctx, cancel := wfCtx()
 	defer cancel()

server/internal/services/workflows_usage_test.go

@@ -0,0 +1,59 @@
+package services
+
+import (
+	"os"
+	"testing"
+
+	"github.com/mrhid6/vantage/server/internal/db"
+	"github.com/mrhid6/vantage/server/internal/models"
+)
+
+func TestMain(m *testing.M) {
+	uri := os.Getenv("VANTAGE_TEST_MONGO_URI")
+	if uri == "" {
+		uri = "mongodb://localhost:27117"
+	}
+	if err := db.Connect(uri, "vantage_test"); err != nil {
+		// No MongoDB available in this environment; skip DB-backed tests.
+		os.Exit(0)
+	}
+	code := m.Run()
+	os.Exit(code)
+}
+
+func mkUsageStep(name string) models.WorkflowStep {
+	return models.WorkflowStep{Name: name, Interpreter: "bash", Script: "echo hi"}
+}
+
+func mkWorkflowWithStep(name, stepID string) models.Workflow {
+	return models.Workflow{Name: name, Steps: []models.WorkflowStepRef{{StepID: stepID, Order: 0, OnFailure: "stop"}}}
+}
+
+func TestStepUsageCounts(t *testing.T) {
+	// A step used by two workflows, a step used by none.
+	used, err := CreateStep(mkUsageStep("used-step"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	unused, err := CreateStep(mkUsageStep("unused-step"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if _, err := CreateWorkflow(mkWorkflowWithStep("wf-a", used.StepID)); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := CreateWorkflow(mkWorkflowWithStep("wf-b", used.StepID)); err != nil {
+		t.Fatal(err)
+	}
+
+	counts, err := StepUsageCounts()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if counts[used.StepID] != 2 {
+		t.Fatalf("used step: want 2, got %d", counts[used.StepID])
+	}
+	if counts[unused.StepID] != 0 {
+		t.Fatalf("unused step: want 0, got %d", counts[unused.StepID])
+	}
+}