Harden recurring cron, bulk delete, error handling; fix semgrep CI

Continued fixes from the multi-agent review:

- recurring tickets cron: now that the parse error is fixed the job runs,
  exposing two latent bugs. (1) next_run_at was only advanced after the
  full success path, so any failure (e.g. a NULL created_by passed to the
  non-nullable assignTicket() $assignedBy -> TypeError) left it in the past
  and re-created a duplicate ticket every cron cycle. Added an atomic
  claimForRun() (conditional UPDATE gated on still-due) called BEFORE
  creation, which also prevents overlapping runs from double-creating.
  (2) The cron used a raw mysqli with no utf8mb4, corrupting non-ASCII
  content; it now uses Database::getConnection(). Also guard the assignment
  so created_by NULL falls back to the assignee.
- bulk delete: attachment files were unlinked inside the DB transaction, so
  an atomic-mode rollback restored rows but the files were already gone.
  deleteTicket() can now defer file removal to the caller, and
  BulkOperationsModel deletes files only after a successful commit.
- UserModel: back-tick the `groups` column (reserved word on MySQL 8.0.2+).
- create_ticket_api.php: stop leaking raw DB/exception messages to callers;
  log server-side and return a generic error. (Also includes a pre-existing
  working-tree tweak that adds title to the manual-ticket dedupe hash.)
- CI: semgrep install failed under PEP 668; add --break-system-packages.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

models/BulkOperationsModel.php

@@ -94,6 +94,10 @@ class BulkOperationsModel
         // Start transaction for data consistency
         $this->conn->begin_transaction();
 
+        // Attachment files for deleted tickets are removed only AFTER a successful
+        // commit, so a rollback can't leave tickets with their files already gone.
+        $filesToDelete = [];
+
         try {
             foreach ($ticketIds as $ticketId) {
                 $ticketId = trim($ticketId);
@@ -200,7 +204,7 @@ class BulkOperationsModel
                             break;
 
                         case 'bulk_delete':
-                            $success = $ticketModel->deleteTicket($ticketId);
+                            $success = $ticketModel->deleteTicket($ticketId, $filesToDelete);
                             if ($success) {
                                 $auditLogModel->log(
                                     $operation['performed_by'],
@@ -249,6 +253,16 @@ class BulkOperationsModel
 
             // Commit the transaction
             $this->conn->commit();
+
+            // Now that the DB delete is durable, remove the physical files. Files
+            // are deleted first; directory entries (no trailing filename) last.
+            foreach ($filesToDelete as $path) {
+                if (is_dir($path)) {
+                    @rmdir($path); // only succeeds if empty
+                } elseif (file_exists($path)) {
+                    @unlink($path);
+                }
+            }
         } catch (Exception $e) {
             // Rollback on any unexpected error
             $this->conn->rollback();

models/RecurringTicketModel.php

@@ -151,6 +151,44 @@ class RecurringTicketModel
         return $items;
     }
 
+    /**
+     * Atomically claim a due schedule for processing.
+     *
+     * Advances next_run_at (and stamps last_run_at) in a single conditional
+     * UPDATE gated on the row still being active and due. Returns true only if
+     * THIS call won the claim. This must be done BEFORE creating the ticket so
+     * that:
+     *   - two overlapping cron runs can't both process the same schedule, and
+     *   - a failure in a later step (ticket create, assignment, audit) can't
+     *     leave next_run_at in the past, which would re-fire — and re-create a
+     *     duplicate ticket — on every subsequent cron run.
+     *
+     * @return bool true if the schedule was claimed by this call
+     */
+    public function claimForRun($recurringId)
+    {
+        $recurring = $this->getById($recurringId);
+        if (!$recurring) {
+            return false;
+        }
+
+        $nextRun = $this->calculateNextRunTime(
+            $recurring['schedule_type'],
+            $recurring['schedule_day'],
+            $recurring['schedule_time']
+        );
+
+        $sql = "UPDATE recurring_tickets
+                   SET last_run_at = NOW(), next_run_at = ?
+                 WHERE recurring_id = ? AND is_active = 1 AND next_run_at <= NOW()";
+        $stmt = $this->conn->prepare($sql);
+        $stmt->bind_param('si', $nextRun, $recurringId);
+        $stmt->execute();
+        $claimed = $stmt->affected_rows > 0;
+        $stmt->close();
+        return $claimed;
+    }
+
     /**
      * Update last run and calculate next run time
      */

models/TicketModel.php

@@ -740,9 +740,13 @@ class TicketModel
      * Admin-only operation. Removes comments, attachments, watchers, dependencies.
      *
      * @param string $ticketId Ticket ID
+     * @param array|null &$deferredFiles When provided, attachment file paths to
+     *        remove are appended here instead of being unlinked immediately, so a
+     *        caller running inside a DB transaction can delete them only AFTER a
+     *        successful commit (avoids destroying files for a rolled-back delete).
      * @return bool Success status
      */
-    public function deleteTicket(string $ticketId): bool
+    public function deleteTicket(string $ticketId, ?array &$deferredFiles = null): bool
     {
         // Collect attachment filenames before deleting DB rows
         $attachmentFiles = [];
@@ -804,13 +808,21 @@ class TicketModel
                 : (isset($GLOBALS['config']['UPLOAD_DIR']) ? $GLOBALS['config']['UPLOAD_DIR'] : dirname(__DIR__) . '/uploads');
             $ticketDir = rtrim($uploadDir, '/') . '/' . $ticketId;
             if (is_dir($ticketDir)) {
-                foreach ($attachmentFiles as $filename) {
-                    $file = $ticketDir . '/' . basename($filename);
-                    if (file_exists($file)) {
-                        @unlink($file);
+                if ($deferredFiles !== null) {
+                    // Defer physical deletion to the caller (post-commit).
+                    foreach ($attachmentFiles as $filename) {
+                        $deferredFiles[] = $ticketDir . '/' . basename($filename);
                     }
+                    $deferredFiles[] = $ticketDir; // dir removed last, only if empty
+                } else {
+                    foreach ($attachmentFiles as $filename) {
+                        $file = $ticketDir . '/' . basename($filename);
+                        if (file_exists($file)) {
+                            @unlink($file);
+                        }
+                    }
+                    @rmdir($ticketDir); // Remove dir only if empty
                 }
-                @rmdir($ticketDir); // Remove dir only if empty
             }
             return true;
         }

models/UserModel.php

@@ -86,7 +86,7 @@ class UserModel
             $user = $result->fetch_assoc();
 
             $updateStmt = $this->conn->prepare(
-                "UPDATE users SET display_name = ?, email = ?, groups = ?, is_admin = ?, last_login = NOW() WHERE username = ?"
+                "UPDATE users SET display_name = ?, email = ?, `groups` = ?, is_admin = ?, last_login = NOW() WHERE username = ?"
             );
             $updateStmt->bind_param("sssis", $displayName, $email, $groups, $isAdmin, $username);
             $updateStmt->execute();
@@ -100,7 +100,7 @@ class UserModel
         } else {
             // Create new user
             $insertStmt = $this->conn->prepare(
-                "INSERT INTO users (username, display_name, email, groups, is_admin, last_login) VALUES (?, ?, ?, ?, ?, NOW())"
+                "INSERT INTO users (username, display_name, email, `groups`, is_admin, last_login) VALUES (?, ?, ?, ?, ?, NOW())"
             );
             $insertStmt->bind_param("ssssi", $username, $displayName, $email, $groups, $isAdmin);
             $insertStmt->execute();
@@ -300,7 +300,7 @@ class UserModel
             return $cached;
         }
 
-        $stmt = $this->conn->prepare("SELECT DISTINCT groups FROM users WHERE groups IS NOT NULL AND groups != ''");
+        $stmt = $this->conn->prepare("SELECT DISTINCT `groups` FROM users WHERE `groups` IS NOT NULL AND `groups` != ''");
         $stmt->execute();
         $result = $stmt->get_result();