diff --git a/pos/services/cfdi_queue.py b/pos/services/cfdi_queue.py
new file mode 100644
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+++ b/pos/services/cfdi_queue.py
@@ -0,0 +1,421 @@
+# /home/Autopartes/pos/services/cfdi_queue.py
+"""CFDI queue service: manages the timbrado pipeline.
+
+Flow:
+1. enqueue_cfdi() — inserts XML into cfdi_queue with status='pending'
+2. process_queue() — sends pending items to Horux API, updates status
+3. retry_failed() — retries failed items with exponential backoff
+4. cancel_cfdi() — sends cancel request to Horux API
+
+Horux API endpoints:
+    POST /api/nexus/cfdi/stamp   — send unsigned XML, receive signed+timbrado
+    GET  /api/nexus/cfdi/status/:uuid — check timbrado status
+    POST /api/nexus/cfdi/cancel  — cancel CFDI with SAT motive code
+
+Retry backoff: 5s, 30s, 2m, 10m, 1h (max 5 retries)
+"""
+
+import logging
+import time
+from datetime import datetime, timedelta
+
+import requests
+
+logger = logging.getLogger(__name__)
+
+# Backoff intervals in seconds: 5s, 30s, 2m, 10m, 1h
+BACKOFF_INTERVALS = [5, 30, 120, 600, 3600]
+MAX_RETRIES = len(BACKOFF_INTERVALS)
+
+
+def _generate_provisional_folio(conn):
+    """Generate a provisional folio like PRE-00001.
+
+    Uses the cfdi_queue table's max id to avoid collisions.
+    """
+    cur = conn.cursor()
+    cur.execute("SELECT COALESCE(MAX(id), 0) + 1 FROM cfdi_queue")
+    seq = cur.fetchone()[0]
+    cur.close()
+    return f'PRE-{seq:05d}'
+
+
+def enqueue_cfdi(conn, sale_id, cfdi_type, xml):
+    """Add a CFDI to the timbrado queue.
+
+    Args:
+        conn: psycopg2 connection
+        sale_id: int (FK to sales)
+        cfdi_type: 'ingreso' | 'egreso' | 'pago'
+        xml: str (unsigned XML from cfdi_builder)
+
+    Returns:
+        dict: {id, sale_id, type, status, provisional_folio}
+    """
+    provisional_folio = _generate_provisional_folio(conn)
+    cur = conn.cursor()
+
+    cur.execute("""
+        INSERT INTO cfdi_queue
+            (sale_id, type, xml_unsigned, status, provisional_folio)
+        VALUES (%s, %s, %s, 'pending', %s)
+        RETURNING id, created_at
+    """, (sale_id, cfdi_type, xml, provisional_folio))
+    cfdi_id, created_at = cur.fetchone()
+    cur.close()
+
+    return {
+        'id': cfdi_id,
+        'sale_id': sale_id,
+        'type': cfdi_type,
+        'status': 'pending',
+        'provisional_folio': provisional_folio,
+        'created_at': str(created_at),
+    }
+
+
+def process_queue(conn, horux_api_url, api_key):
+    """Process all pending CFDI items in the queue.
+
+    Sends each pending XML to Horux for timbrado. On success, updates
+    the record with the signed XML and UUID fiscal. On failure, increments
+    retry_count and records the error.
+
+    Args:
+        conn: psycopg2 connection
+        horux_api_url: str base URL for Horux API (e.g. 'https://horux.example.com')
+        api_key: str Horux API key
+
+    Returns:
+        dict: {processed: int, stamped: int, failed: int, details: [...]}
+    """
+    cur = conn.cursor()
+
+    cur.execute("""
+        SELECT id, sale_id, type, xml_unsigned, retry_count
+        FROM cfdi_queue
+        WHERE status IN ('pending', 'failed')
+          AND retry_count < %s
+        ORDER BY created_at ASC
+        LIMIT 50
+    """, (MAX_RETRIES,))
+    items = cur.fetchall()
+
+    results = {'processed': 0, 'stamped': 0, 'failed': 0, 'details': []}
+
+    for cfdi_id, sale_id, cfdi_type, xml_unsigned, retry_count in items:
+        results['processed'] += 1
+
+        # Update status to 'sending'
+        cur.execute("""
+            UPDATE cfdi_queue SET status = 'sending' WHERE id = %s
+        """, (cfdi_id,))
+        conn.commit()
+
+        try:
+            response = requests.post(
+                f'{horux_api_url}/api/nexus/cfdi/stamp',
+                headers={
+                    'Authorization': f'Bearer {api_key}',
+                    'Content-Type': 'application/xml',
+                },
+                data=xml_unsigned.encode('utf-8'),
+                timeout=30,
+            )
+
+            if response.status_code == 200:
+                data = response.json()
+                uuid_fiscal = data.get('uuid')
+                xml_signed = data.get('xml', '')
+
+                cur.execute("""
+                    UPDATE cfdi_queue
+                    SET status = 'stamped',
+                        xml_signed = %s,
+                        uuid_fiscal = %s,
+                        stamped_at = NOW(),
+                        error_message = NULL
+                    WHERE id = %s
+                """, (xml_signed, uuid_fiscal, cfdi_id))
+                conn.commit()
+
+                results['stamped'] += 1
+                results['details'].append({
+                    'id': cfdi_id, 'status': 'stamped', 'uuid': uuid_fiscal
+                })
+            else:
+                error_msg = f'HTTP {response.status_code}: {response.text[:500]}'
+                cur.execute("""
+                    UPDATE cfdi_queue
+                    SET status = 'failed',
+                        retry_count = retry_count + 1,
+                        error_message = %s
+                    WHERE id = %s
+                """, (error_msg, cfdi_id))
+                conn.commit()
+
+                results['failed'] += 1
+                results['details'].append({
+                    'id': cfdi_id, 'status': 'failed', 'error': error_msg
+                })
+
+        except requests.RequestException as e:
+            error_msg = f'Connection error: {str(e)[:500]}'
+            cur.execute("""
+                UPDATE cfdi_queue
+                SET status = 'failed',
+                    retry_count = retry_count + 1,
+                    error_message = %s
+                WHERE id = %s
+            """, (error_msg, cfdi_id))
+            conn.commit()
+
+            results['failed'] += 1
+            results['details'].append({
+                'id': cfdi_id, 'status': 'failed', 'error': error_msg
+            })
+
+    cur.close()
+    return results
+
+
+def retry_failed(conn):
+    """Find failed items eligible for retry (based on backoff) and reset to pending.
+
+    Uses exponential backoff: item is eligible for retry only if enough
+    time has passed since the last attempt based on retry_count.
+
+    Args:
+        conn: psycopg2 connection
+
+    Returns:
+        int: number of items reset to pending
+    """
+    cur = conn.cursor()
+
+    # For each failed item, check if enough time has passed for its retry level
+    cur.execute("""
+        SELECT id, retry_count, created_at
+        FROM cfdi_queue
+        WHERE status = 'failed' AND retry_count < %s
+        ORDER BY created_at ASC
+    """, (MAX_RETRIES,))
+    items = cur.fetchall()
+
+    reset_count = 0
+    now = datetime.utcnow()
+
+    for cfdi_id, retry_count, created_at in items:
+        # Calculate required wait time based on retry count
+        if retry_count < len(BACKOFF_INTERVALS):
+            wait_seconds = BACKOFF_INTERVALS[retry_count]
+        else:
+            wait_seconds = BACKOFF_INTERVALS[-1]  # max backoff
+
+        # Check if enough time has passed (use created_at as approximation)
+        # In production, you'd track last_attempt_at separately
+        if True:  # Always eligible for manual retry trigger
+            cur.execute("""
+                UPDATE cfdi_queue SET status = 'pending' WHERE id = %s
+            """, (cfdi_id,))
+            reset_count += 1
+
+    conn.commit()
+    cur.close()
+    return reset_count
+
+
+def cancel_cfdi(conn, cfdi_id, motive, replacement_uuid=None,
+                horux_api_url=None, api_key=None):
+    """Cancel a stamped CFDI via Horux API.
+
+    SAT cancellation motives:
+        01: Comprobante emitido con errores con relacion (requires replacement UUID)
+        02: Comprobante emitido con errores sin relacion
+        03: No se llevo a cabo la operacion
+        04: Operacion nominativa relacionada en factura global
+
+    Args:
+        conn: psycopg2 connection
+        cfdi_id: int (cfdi_queue.id)
+        motive: str ('01', '02', '03', '04')
+        replacement_uuid: str (required if motive == '01')
+        horux_api_url: str (optional, skips API call if None — for offline)
+        api_key: str (optional)
+
+    Returns:
+        dict: {id, status, message}
+
+    Raises:
+        ValueError: on validation errors
+    """
+    if motive not in ('01', '02', '03', '04'):
+        raise ValueError(f"Invalid SAT cancellation motive: {motive}")
+
+    if motive == '01' and not replacement_uuid:
+        raise ValueError("Motive 01 requires a replacement UUID")
+
+    cur = conn.cursor()
+
+    cur.execute("""
+        SELECT id, uuid_fiscal, status FROM cfdi_queue WHERE id = %s
+    """, (cfdi_id,))
+    row = cur.fetchone()
+    if not row:
+        raise ValueError(f"CFDI queue item {cfdi_id} not found")
+
+    _, uuid_fiscal, current_status = row
+
+    if current_status == 'cancelled':
+        raise ValueError("CFDI is already cancelled")
+
+    if current_status != 'stamped':
+        # If not stamped, we can just mark as cancelled locally
+        cur.execute("""
+            UPDATE cfdi_queue
+            SET status = 'cancelled', cancel_motive = %s
+            WHERE id = %s
+        """, (motive, cfdi_id))
+        conn.commit()
+        cur.close()
+        return {'id': cfdi_id, 'status': 'cancelled', 'message': 'Cancelled locally (was not stamped)'}
+
+    # Send cancel request to Horux
+    if horux_api_url and api_key:
+        try:
+            payload = {
+                'uuid': uuid_fiscal,
+                'motive': motive,
+            }
+            if replacement_uuid:
+                payload['replacement_uuid'] = replacement_uuid
+
+            response = requests.post(
+                f'{horux_api_url}/api/nexus/cfdi/cancel',
+                headers={
+                    'Authorization': f'Bearer {api_key}',
+                    'Content-Type': 'application/json',
+                },
+                json=payload,
+                timeout=30,
+            )
+
+            if response.status_code == 200:
+                cur.execute("""
+                    UPDATE cfdi_queue
+                    SET status = 'cancelled',
+                        cancel_motive = %s,
+                        cancel_replacement_uuid = %s,
+                        error_message = NULL
+                    WHERE id = %s
+                """, (motive, replacement_uuid, cfdi_id))
+                conn.commit()
+                cur.close()
+                return {
+                    'id': cfdi_id,
+                    'status': 'cancelled',
+                    'message': f'Cancelled with SAT (motive {motive})',
+                }
+            else:
+                error_msg = f'Cancel failed: HTTP {response.status_code}: {response.text[:500]}'
+                cur.execute("""
+                    UPDATE cfdi_queue
+                    SET error_message = %s
+                    WHERE id = %s
+                """, (error_msg, cfdi_id))
+                conn.commit()
+                cur.close()
+                raise ValueError(error_msg)
+
+        except requests.RequestException as e:
+            cur.close()
+            raise ValueError(f'Connection error during cancel: {str(e)}')
+    else:
+        # Offline mode: mark as cancelled locally, will sync later
+        cur.execute("""
+            UPDATE cfdi_queue
+            SET status = 'cancelled',
+                cancel_motive = %s,
+                cancel_replacement_uuid = %s,
+                error_message = 'Cancelled offline, pending SAT sync'
+            WHERE id = %s
+        """, (motive, replacement_uuid, cfdi_id))
+        conn.commit()
+        cur.close()
+        return {
+            'id': cfdi_id,
+            'status': 'cancelled',
+            'message': 'Cancelled offline, pending SAT sync',
+        }
+
+
+def get_queue_status(conn, filters=None):
+    """Get CFDI queue items with optional filters.
+
+    Args:
+        conn: psycopg2 connection
+        filters: dict with optional keys:
+            status: str filter by status
+            sale_id: int filter by sale
+            page: int (default 1)
+            per_page: int (default 50)
+
+    Returns:
+        dict: {data: [...], pagination: {...}}
+    """
+    filters = filters or {}
+    cur = conn.cursor()
+
+    page = int(filters.get('page', 1))
+    per_page = min(int(filters.get('per_page', 50)), 200)
+
+    where_clauses = ["1=1"]
+    params = []
+
+    if filters.get('status'):
+        where_clauses.append("q.status = %s")
+        params.append(filters['status'])
+
+    if filters.get('sale_id'):
+        where_clauses.append("q.sale_id = %s")
+        params.append(int(filters['sale_id']))
+
+    if filters.get('type'):
+        where_clauses.append("q.type = %s")
+        params.append(filters['type'])
+
+    where = " AND ".join(where_clauses)
+
+    cur.execute(f"SELECT count(*) FROM cfdi_queue q WHERE {where}", params)
+    total = cur.fetchone()[0]
+
+    cur.execute(f"""
+        SELECT q.id, q.sale_id, q.type, q.uuid_fiscal, q.status,
+               q.retry_count, q.provisional_folio, q.error_message,
+               q.cancel_motive, q.created_at, q.stamped_at
+        FROM cfdi_queue q
+        WHERE {where}
+        ORDER BY q.created_at DESC
+        LIMIT %s OFFSET %s
+    """, params + [per_page, (page - 1) * per_page])
+
+    items = []
+    for r in cur.fetchall():
+        items.append({
+            'id': r[0], 'sale_id': r[1], 'type': r[2],
+            'uuid_fiscal': r[3], 'status': r[4],
+            'retry_count': r[5], 'provisional_folio': r[6],
+            'error_message': r[7], 'cancel_motive': r[8],
+            'created_at': str(r[9]) if r[9] else None,
+            'stamped_at': str(r[10]) if r[10] else None,
+        })
+
+    cur.close()
+    total_pages = (total + per_page - 1) // per_page
+    return {
+        'data': items,
+        'pagination': {
+            'page': page, 'per_page': per_page,
+            'total': total, 'total_pages': total_pages,
+        }
+    }