fix: chat attachment detection — 3-method fallback + deferred retry

ab_ai_mail.py: when a user sends a file via Odoo 18 Discuss, the zip
was going through /dispatch (text-only) instead of /upload, causing the
bot to respond "I'm unable to locate the zip file" because attachment_ids
was empty in the message_post override.

Root cause: Odoo 18 Discuss links file attachments to mail.message
records via three different mechanisms depending on the upload path, and
we only checked one (the Many2many relation table).

Fixes:
1. Three-method attachment detection in message_post:
   - Method 1: result.attachment_ids (Many2many relation table)
   - Method 2: ir.attachment with res_model='mail.message' (Odoo 15+ style)
   - Method 3: attachment IDs parsed from href URLs in the HTML body
2. Deferred retry in _agent_thread: if att_data is still empty but a
   message_id is known, sleep 1s then re-read via a fresh DB cursor so
   we see data committed after message_post returned (timing race fix)
3. Skip zero-byte attachments and warn instead of silently using them
4. Pass message_id to the background thread (new kwarg, backward compat)
5. Add debug logging so future issues can be diagnosed from Odoo logs

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

addons/activeblue_ai/models/ab_ai_mail.py

@@ -3,6 +3,7 @@ import base64
 import logging
 import re
 import threading
+import time
 
 import requests as _requests
 from markupsafe import Markup, escape
@@ -11,6 +12,8 @@ from odoo import SUPERUSER_ID, api, registry as odoo_registry, models
 _logger = logging.getLogger(__name__)
 
 _HTML_TAG = re.compile(r'<[^>]+>')
+# Matches /web/content/ir.attachment/<id>/ or /web/image/ir.attachment/<id>/
+_ATT_URL_RE = re.compile(r'/(?:web/content|web/image)/ir\.attachment/(\d+)/')
 
 
 def _strip_html(html: str) -> str:
@@ -38,14 +41,57 @@ def _post_bot_reply(db: str, channel_id: int, bot_partner_id: int, reply_text: s
         _logger.error('_post_bot_reply failed channel=%s: %s', channel_id, exc)
 
 
+def _read_message_attachments(db: str, message_id: int) -> list[tuple[str, bytes, str]]:
+    """Re-read attachment bytes for a message using a fresh DB cursor.
+
+    Called from the background agent thread as a fallback when the
+    message_post override ran before the transaction that linked the
+    attachment to the message had committed (common in Odoo 18 Discuss).
+    Retries up to 3 times with 0.5s delay.
+    """
+    for attempt in range(3):
+        try:
+            with odoo_registry(db).cursor() as cr:
+                env = api.Environment(cr, SUPERUSER_ID, {})
+                msg = env['mail.message'].browse(message_id)
+                att_data = []
+                for att in msg.attachment_ids:
+                    try:
+                        data = base64.b64decode(att.datas) if att.datas else b''
+                        if data:
+                            att_data.append((att.name or 'attachment', data,
+                                             att.mimetype or 'application/octet-stream'))
+                    except Exception as exc:
+                        _logger.warning('_read_message_attachments: decode att %s: %s',
+                                        att.id, exc)
+                if att_data:
+                    return att_data
+        except Exception as exc:
+            _logger.warning('_read_message_attachments attempt %d: %s', attempt, exc)
+        if attempt < 2:
+            time.sleep(0.5)
+    return []
+
+
 def _agent_thread(db: str, uid: int, text: str, att_data: list,
                   bot_partner_id: int, channel_id: int,
-                  bot_url: str, bot_secret: str):
+                  bot_url: str, bot_secret: str, message_id: int = 0):
     """
     Background thread: calls the agent service and posts the reply.
     All messages — text, files, or both — are routed here so the LLM
     handles every response.  Nothing is intercepted or templated in Odoo.
     """
+    # Deferred attachment detection: if no att_data was found in message_post
+    # (happens in Odoo 18 when the transaction linking attachments to the message
+    # commits after our override already ran), wait briefly and retry using a
+    # fresh DB cursor so we see the committed attachment data.
+    if not att_data and message_id:
+        time.sleep(1.0)
+        att_data = _read_message_attachments(db, message_id)
+        if att_data:
+            _logger.info('_agent_thread: deferred read found %d attachment(s) for msg %d',
+                         len(att_data), message_id)
+
     try:
         headers = {}
         if bot_secret:
@@ -124,22 +170,49 @@ class DiscussChannel(models.Model):
             return result
 
         text = _strip_html(body)
+        message_id = result.id
+
+        # ── Attachment detection ─────────────────────────────────────────────
+        # In Odoo 18, file attachments in Discuss can be linked to a message
+        # via three different mechanisms depending on the upload path.  Try all
+        # three so we don't miss any files.
+
+        # Method 1: standard Many2many relation table (mail.message → ir.attachment)
         attachments = result.attachment_ids
 
-        # Nothing to process
+        # Method 2: ir.attachment records with res_model='mail.message' (Odoo 15+ style)
-        if not text and not attachments:
+        if not attachments:
-            return result
+            attachments = self.env['ir.attachment'].sudo().search([
+                ('res_model', '=', 'mail.message'),
+                ('res_id', '=', message_id),
+            ])
 
-        # Read attachment bytes NOW, inside the current transaction
+        # Method 3: attachment IDs embedded in HTML body links
+        # e.g. <a href="/web/content/ir.attachment/123/...">file.zip</a>
+        if not attachments:
+            body_att_ids = [int(m) for m in _ATT_URL_RE.findall(body or '')]
+            if body_att_ids:
+                attachments = self.env['ir.attachment'].sudo().browse(body_att_ids).exists()
+
+        # Read the raw bytes for each attachment found
         att_data: list[tuple[str, bytes, str]] = []
         for att in attachments:
             try:
                 data = base64.b64decode(att.datas) if att.datas else b''
-                att_data.append((att.name or 'attachment', data,
+                if data:
-                                 att.mimetype or 'application/octet-stream'))
+                    att_data.append((att.name or 'attachment', data,
+                                     att.mimetype or 'application/octet-stream'))
+                else:
+                    _logger.warning('message_post: attachment %s (%s) has no data — '
+                                    'will retry in background thread', att.id, att.name)
             except Exception as exc:
                 _logger.warning('Could not read attachment %s: %s', att.id, exc)
 
+        # Nothing to process
+        if not text and not att_data and not attachments:
+            return result
+
+        # ── Fire the agent ───────────────────────────────────────────────────
         human_partner = member_partners.filtered(lambda p: p != bot_partner)[:1]
         user = self.env['res.users'].search([('partner_id', '=', human_partner.id)], limit=1)
         uid = user.id if user else self.env.uid
@@ -154,11 +227,18 @@ class DiscussChannel(models.Model):
         channel_id = self.id
         bot_partner_id = bot_partner.id
 
-        # Launch the agent call in a daemon thread — message_post returns immediately
+        _logger.debug('message_post: channel=%s msg=%s text=%r att_count=%d deferred=%s',
+                      channel_id, message_id, text[:60] if text else '',
+                      len(att_data), bool(attachments and not att_data))
+
+        # Launch the agent call in a daemon thread — message_post returns immediately.
+        # message_id is passed so the thread can re-read attachments if they weren't
+        # yet committed when we read them above (Odoo 18 timing race).
         threading.Thread(
             target=_agent_thread,
             args=(db, uid, text, att_data, bot_partner_id, channel_id,
                   bot_url, bot_secret),
+            kwargs={'message_id': message_id},
             daemon=True,
         ).start()