feat(admin): awaiting-link reminders, placeholder claim-and-issue, and billing health

sweepAwaitingLink chases paid-but-unlinked self-hosted placeholders at 24h/72h.
claimPlaceholderLink rewrites a placeholder's identity to the install's real
UUID, re-points the subscription, and issues from it — linking and claiming are
one call because the payment already happened. staffBillingHealth surfaces
failed webhook handlers and unlinked paid placeholders.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

admin/internal/api/checkout.go

@@ -9,6 +9,7 @@ import (
 	"github.com/google/uuid"
 	"github.com/mrhid6/vantage/admin/internal/audit"
 	"github.com/mrhid6/vantage/admin/internal/auth"
+	"github.com/mrhid6/vantage/admin/internal/billing"
 	"github.com/mrhid6/vantage/admin/internal/catalogue"
 	"github.com/mrhid6/vantage/admin/internal/db"
 	"github.com/mrhid6/vantage/admin/internal/models"
@@ -161,6 +162,76 @@ func updateEntitlement(c *gin.Context) {
 	c.JSON(http.StatusOK, gin.H{"entitlement": next, "pending": next.Pending()})
 }
 
+// claimPlaceholderLink binds a paid self-hosted placeholder to the customer's
+// real install UUID, then issues.
+//
+// :id is the placeholder (generated at checkout, carried in the subscription's
+// custom_data); the body carries the UUID the install actually reports. The
+// licence must bind to that real UUID (spec 1 has no unbound licence), so the
+// placeholder row's identity is rewritten to it and the subscription re-pointed,
+// then billing issues from the recorded subscription. Linking and claiming stay
+// one call here because, unlike Free, the payment already happened.
+func claimPlaceholderLink(c *gin.Context) {
+	inst, ok := ownedInstance(c, c.Param("id"))
+	if !ok {
+		return
+	}
+	if !inst.Placeholder {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "this instance is already linked"})
+		return
+	}
+	var body struct {
+		InstanceID string `json:"instance_id"`
+	}
+	if err := c.ShouldBindJSON(&body); err != nil || body.InstanceID == "" {
+		c.JSON(http.StatusBadRequest, gin.H{"error": "instance_id is required"})
+		return
+	}
+	ctx := c.Request.Context()
+
+	// The real UUID must be free across every account — the unique index on
+	// instance_id is the tenant-isolation property, so refuse rather than collide.
+	if n, _ := db.Admin("admin_instances").CountDocuments(ctx,
+		bson.M{"instance_id": body.InstanceID}); n > 0 {
+		c.JSON(http.StatusConflict, gin.H{"error": "that instance ID is already linked"})
+		return
+	}
+
+	placeholderID := inst.InstanceID
+	if _, err := db.Admin("admin_instances").UpdateOne(ctx,
+		bson.M{"instance_id": placeholderID},
+		bson.M{"$set": bson.M{
+			"instance_id": body.InstanceID,
+			"status":      models.StatusActive,
+			"placeholder": false,
+		}}); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+	// Re-point the subscription from the placeholder id to the real UUID so
+	// billing.IssueForInstance (and every later webhook) finds it.
+	if _, err := db.Admin("subscriptions").UpdateMany(ctx,
+		bson.M{"instance_id": placeholderID},
+		bson.M{"$set": bson.M{"instance_id": body.InstanceID}}); err != nil {
+		c.JSON(http.StatusInternalServerError, gin.H{"error": err.Error()})
+		return
+	}
+
+	if err := billing.IssueForInstance(ctx, body.InstanceID); err != nil {
+		// The link stuck; issuance did not. The reconciler and a retry recover it,
+		// and the customer is not blocked from linking. Surface it, do not roll back.
+		c.JSON(http.StatusAccepted, gin.H{
+			"instance_id": body.InstanceID,
+			"warning":     "linked, but licence issuance is pending: " + err.Error()})
+		return
+	}
+	audit.Write(ctx, models.AuditEntry{
+		Actor: auth.Current(c).Email, Action: "instance.placeholder_linked",
+		AccountID: inst.AccountID, Target: body.InstanceID,
+		Detail: "from placeholder " + placeholderID, IP: c.ClientIP()})
+	c.JSON(http.StatusOK, gin.H{"instance_id": body.InstanceID})
+}
+
 // billingPortal mints a Paddle customer-portal URL. The account must already
 // have a paddle_customer_id, which it learns from its first subscription webhook.
 func billingPortal(c *gin.Context) {

admin/internal/api/routes.go

@@ -84,6 +84,9 @@ func Routes(cfg config.Config) http.Handler {
 			auth.RequireAccountRole(models.AccountRoleOwner, models.AccountRoleAdmin),
 			updateEntitlement)
 		cust.POST("/billing/portal", billingPortal)
+		cust.POST("/instances/:id/claim-link",
+			auth.RequireAccountRole(models.AccountRoleOwner, models.AccountRoleAdmin),
+			claimPlaceholderLink)
 		cust.GET("/instances/:id/license", getInstanceLicense)
 		cust.GET("/instances/:id/license/download", downloadInstanceLicense)
 		cust.GET("/instances/:id/members", listInstanceMembers)
@@ -125,6 +128,7 @@ func Routes(cfg config.Config) http.Handler {
 		staff.PUT("/instances/:id/entitlement", staffSetEntitlement)
 		staff.GET("/audit", staffAudit)
 		staff.GET("/health/injection", staffInjectionHealth)
+		staff.GET("/health/billing", staffBillingHealth)
 	}
 
 	return r

admin/internal/api/staff.go

@@ -380,6 +380,29 @@ func staffListLicenses(c *gin.Context) {
 	c.JSON(http.StatusOK, lics)
 }
 
+// staffBillingHealth surfaces webhook handlers that failed and paid-but-unlinked
+// placeholders, so a customer who paid and got nothing is visible rather than
+// stuck in a support queue.
+func staffBillingHealth(c *gin.Context) {
+	ctx := c.Request.Context()
+	failed := []models.PaddleEvent{}
+	if cur, err := db.Admin("paddle_events").Find(ctx,
+		bson.M{"processed_at": bson.M{"$exists": false}, "error": bson.M{"$ne": ""}}); err == nil {
+		_ = cur.All(ctx, &failed)
+	}
+	unlinked := []models.Instance{}
+	if cur, err := db.Admin("admin_instances").Find(ctx,
+		bson.M{"placeholder": true, "status": models.StatusAwaitingLink}); err == nil {
+		_ = cur.All(ctx, &unlinked)
+	}
+	c.JSON(http.StatusOK, gin.H{
+		"failed_events":   failed,
+		"failed_count":    len(failed),
+		"unlinked_paid":   unlinked,
+		"unlinked_count":  len(unlinked),
+	})
+}
+
 func staffListPlans(c *gin.Context) {
 	cur, err := db.Admin("plans").Find(c.Request.Context(), bson.M{})
 	if err != nil {