Fix avg resolution time using dedicated closed_at column

The dashboard's "Avg Resolution" stat was using updated_at, which gets
overwritten on any post-close edit (title change, comment, etc.),
inflating the metric. Also fixes "Closed Today" count for the same reason.

- Add closed_at TIMESTAMP column to tickets table
- Set closed_at on close, preserve on re-edit, clear on reopen
- Update StatsModel queries to use closed_at instead of updated_at
- Add migration script with audit log backfill for existing tickets

Run: php scripts/add_closed_at_column.php

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

models/StatsModel.php

@@ -84,12 +84,12 @@ class StatsModel {
      * Get average resolution time in hours
      */
     public function getAverageResolutionTime(): float {
-        $sql = "SELECT AVG(TIMESTAMPDIFF(HOUR, created_at, updated_at)) as avg_hours
+        $sql = "SELECT AVG(TIMESTAMPDIFF(HOUR, created_at, closed_at)) as avg_hours
                 FROM tickets
                 WHERE status = 'Closed'
                 AND created_at IS NOT NULL
-                AND updated_at IS NOT NULL
+                AND closed_at IS NOT NULL
-                AND updated_at > created_at";
+                AND closed_at > created_at";
         $result = $this->conn->query($sql);
         $row = $result->fetch_assoc();
         return $row['avg_hours'] ? round($row['avg_hours'], 1) : 0;
@@ -119,7 +119,7 @@ class StatsModel {
      * Get count of tickets closed today
      */
     public function getTicketsClosedToday(): int {
-        $sql = "SELECT COUNT(*) as count FROM tickets WHERE status = 'Closed' AND DATE(updated_at) = CURDATE()";
+        $sql = "SELECT COUNT(*) as count FROM tickets WHERE status = 'Closed' AND DATE(closed_at) = CURDATE()";
         $result = $this->conn->query($sql);
         $row = $result->fetch_assoc();
         return (int)$row['count'];
@@ -211,11 +211,11 @@ class StatsModel {
             SUM(CASE WHEN status = 'Closed' THEN 1 ELSE 0 END) as closed_tickets,
             SUM(CASE WHEN DATE(created_at) = CURDATE() THEN 1 ELSE 0 END) as created_today,
             SUM(CASE WHEN YEARWEEK(created_at, 1) = YEARWEEK(CURDATE(), 1) THEN 1 ELSE 0 END) as created_this_week,
-            SUM(CASE WHEN status = 'Closed' AND DATE(updated_at) = CURDATE() THEN 1 ELSE 0 END) as closed_today,
+            SUM(CASE WHEN status = 'Closed' AND DATE(closed_at) = CURDATE() THEN 1 ELSE 0 END) as closed_today,
             SUM(CASE WHEN assigned_to IS NULL AND status != 'Closed' THEN 1 ELSE 0 END) as unassigned,
             SUM(CASE WHEN priority = 1 AND status != 'Closed' THEN 1 ELSE 0 END) as critical,
-            AVG(CASE WHEN status = 'Closed' AND updated_at > created_at
+            AVG(CASE WHEN status = 'Closed' AND closed_at > created_at
-                THEN TIMESTAMPDIFF(HOUR, created_at, updated_at) ELSE NULL END) as avg_resolution
+                THEN TIMESTAMPDIFF(HOUR, created_at, closed_at) ELSE NULL END) as avg_resolution
             FROM tickets";
 
         $countsResult = $this->conn->query($countsSql);

models/TicketModel.php

@@ -216,6 +216,9 @@ class TicketModel {
      * @return array ['success' => bool, 'error' => string|null, 'conflict' => bool]
      */
     public function updateTicket(array $ticketData, ?int $updatedBy = null, ?string $expectedUpdatedAt = null): array {
+        // closed_at: set on close (preserve if already set), clear on reopen
+        $closedAtClause = "closed_at = CASE WHEN ? = 'Closed' THEN COALESCE(closed_at, NOW()) ELSE NULL END";
+
         // Build query with optional optimistic locking
         if ($expectedUpdatedAt !== null) {
             // Optimistic locking enabled - check that updated_at hasn't changed
@@ -227,7 +230,8 @@ class TicketModel {
                     category = ?,
                     type = ?,
                     updated_by = ?,
-                    updated_at = NOW()
+                    updated_at = NOW(),
+                    $closedAtClause
                     WHERE ticket_id = ? AND updated_at = ?";
         } else {
             // No optimistic locking
@@ -239,7 +243,8 @@ class TicketModel {
                     category = ?,
                     type = ?,
                     updated_by = ?,
-                    updated_at = NOW()
+                    updated_at = NOW(),
+                    $closedAtClause
                     WHERE ticket_id = ?";
         }
 
@@ -250,7 +255,7 @@ class TicketModel {
 
         if ($expectedUpdatedAt !== null) {
             $stmt->bind_param(
-                "sissssiis",
+                "sissssisis",
                 $ticketData['title'],
                 $ticketData['priority'],
                 $ticketData['status'],
@@ -258,12 +263,13 @@ class TicketModel {
                 $ticketData['category'],
                 $ticketData['type'],
                 $updatedBy,
+                $ticketData['status'],
                 $ticketData['ticket_id'],
                 $expectedUpdatedAt
             );
         } else {
             $stmt->bind_param(
-                "sissssii",
+                "sissssisi",
                 $ticketData['title'],
                 $ticketData['priority'],
                 $ticketData['status'],
@@ -271,6 +277,7 @@ class TicketModel {
                 $ticketData['category'],
                 $ticketData['type'],
                 $updatedBy,
+                $ticketData['status'],
                 $ticketData['ticket_id']
             );
         }

scripts/add_closed_at_column.php

@@ -0,0 +1,72 @@
+#!/usr/bin/env php
+<?php
+/**
+ * Migration: Add closed_at column to tickets table
+ *
+ * Adds a dedicated timestamp for when tickets are closed,
+ * so avg resolution time isn't inflated by post-close edits.
+ *
+ * Usage: php scripts/add_closed_at_column.php
+ */
+
+require_once dirname(__DIR__) . '/config/config.php';
+
+$conn = new mysqli(
+    $GLOBALS['config']['DB_HOST'],
+    $GLOBALS['config']['DB_USER'],
+    $GLOBALS['config']['DB_PASS'],
+    $GLOBALS['config']['DB_NAME']
+);
+
+if ($conn->connect_error) {
+    die("Database connection failed: " . $conn->connect_error . "\n");
+}
+
+echo "Adding closed_at column to tickets table...\n";
+
+// Add the column if it doesn't exist
+$result = $conn->query("SHOW COLUMNS FROM tickets LIKE 'closed_at'");
+if ($result->num_rows > 0) {
+    echo "Column 'closed_at' already exists, skipping ALTER TABLE.\n";
+} else {
+    $sql = "ALTER TABLE tickets ADD COLUMN closed_at TIMESTAMP NULL DEFAULT NULL AFTER updated_at";
+    if ($conn->query($sql)) {
+        echo "Column added successfully.\n";
+    } else {
+        die("Failed to add column: " . $conn->error . "\n");
+    }
+
+    // Add index for stats queries
+    $conn->query("CREATE INDEX idx_tickets_closed_at ON tickets (closed_at)");
+    echo "Index created.\n";
+}
+
+// Backfill: For existing closed tickets, use the audit log to find when they were closed
+echo "\nBackfilling closed_at from audit log...\n";
+
+$sql = "UPDATE tickets t
+        JOIN (
+            SELECT entity_id as ticket_id, MIN(created_at) as first_closed
+            FROM audit_log
+            WHERE entity_type = 'ticket'
+            AND action_type = 'update'
+            AND details LIKE '%\"status\":\"Closed\"%'
+            GROUP BY entity_id
+        ) al ON t.ticket_id = al.ticket_id
+        SET t.closed_at = al.first_closed
+        WHERE t.status = 'Closed' AND t.closed_at IS NULL";
+
+$result = $conn->query($sql);
+$backfilled = $conn->affected_rows;
+echo "Backfilled $backfilled tickets from audit log.\n";
+
+// For any remaining closed tickets without audit log entries, use updated_at as fallback
+$sql = "UPDATE tickets SET closed_at = updated_at WHERE status = 'Closed' AND closed_at IS NULL";
+$conn->query($sql);
+$fallback = $conn->affected_rows;
+if ($fallback > 0) {
+    echo "Used updated_at as fallback for $fallback tickets without audit log entries.\n";
+}
+
+echo "\nMigration complete!\n";
+$conn->close();