nanobot/channels/telegram.py

@@ -16,6 +16,10 @@ from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.config.schema import TelegramConfig
 
+# Telegram API limits
+REMOTE_MEDIA_SIZE_LIMIT = 100_000_000  # 100MB for remote URLs
+TELEGRAM_PHOTO_SIZE_LIMIT = 10_000_000  # 10MB for photos
+
 
 def _markdown_to_telegram_html(text: str) -> str:
     """
@@ -250,7 +254,7 @@ class TelegramChannel(BaseChannel):
             try:
                 # Fetch remote URLs
                 if path.startswith(("http://", "https://")):
-                    content, mime = await fetch_media(path, max_bytes=100_000_000)
+                    content, mime = await fetch_media(path, max_bytes=REMOTE_MEDIA_SIZE_LIMIT)
                     kind = classify_media(mime)
                 else:
                     # Local file
@@ -270,7 +274,13 @@ class TelegramChannel(BaseChannel):
                         try:
                             content = optimize_image(path, max_bytes=6_000_000)
                         except Exception as e:
-                            logger.warning(f"Image optimization failed: {e}, sending original")
+                            logger.warning(f"Image optimization failed: {e}")
+                            # Check if original is under Telegram's limit
+                            if len(content) <= TELEGRAM_PHOTO_SIZE_LIMIT:
+                                logger.info("Using original image (under 10MB limit)")
+                            else:
+                                logger.error(f"Original image too large ({len(content)} bytes), skipping")
+                                continue
 
                 processed_media.append((path, kind, content))
 
@@ -333,12 +343,14 @@ class TelegramChannel(BaseChannel):
                 )
 
         # Send separate media
-        for i, (path, kind, content) in enumerate(processed_media):
+        first_separate = True
+        for path, kind, content in processed_media:
             if path in grouping["album"]:
                 continue  # Already sent in album
 
             # Only first separate item gets caption
-            item_caption = media_caption if i == 0 else None
+            item_caption = media_caption if first_separate else None
+            first_separate = False
 
             if kind == MediaKind.IMAGE:
                 await self._app.bot.send_photo(

nanobot/channels/telegram_media.py

@@ -61,7 +61,6 @@ def detect_mime(path: str, content: bytes | None = None) -> str:
                 return mime
         except Exception as e:
             logger.debug(f"Magic detection failed, falling back to extension: {e}")
-            pass  # Fall through to extension-based detection
 
     # Extension-based detection
     mime_type, _ = mimetypes.guess_type(path)
@@ -169,27 +168,26 @@ def optimize_image(path: str, max_bytes: int = TELEGRAM_PHOTO_SIZE_LIMIT) -> byt
     Raises:
         ValueError: If image cannot be optimized under limit
     """
-    # Load image
-    img = Image.open(path)
+    # Load image with context manager to ensure file handle is closed
+    with Image.open(path) as img:
+        # Convert HEIC to JPEG
+        if is_heic_format(path):
+            if not HAS_HEIF:
+                raise ValueError("pillow-heif not available for HEIC conversion")
+            # Convert to RGB (HEIC → JPEG)
+            if img.mode != "RGB":
+                img = img.convert("RGB")
+            return _optimize_jpeg(img, max_bytes)
 
-    # Convert HEIC to JPEG
-    if is_heic_format(path):
-        if not HAS_HEIF:
-            raise ValueError("pillow-heif not available for HEIC conversion")
-        # Convert to RGB (HEIC → JPEG)
+        # PNG with alpha channel - preserve it
+        if img.mode == "RGBA" or img.mode == "LA":
+            return _optimize_png(img, max_bytes)
+
+        # Everything else → convert to JPEG and optimize
         if img.mode != "RGB":
             img = img.convert("RGB")
         return _optimize_jpeg(img, max_bytes)
 
-    # PNG with alpha channel - preserve it
-    if img.mode == "RGBA" or img.mode == "LA":
-        return _optimize_png(img, max_bytes)
-
-    # Everything else → convert to JPEG and optimize
-    if img.mode != "RGB":
-        img = img.convert("RGB")
-    return _optimize_jpeg(img, max_bytes)
-
 
 def _optimize_jpeg(img: Image.Image, max_bytes: int) -> bytes:
     """Optimize JPEG with size/quality grid."""