Ensure success and error emails always have a subject

- Use EMAIL_SUBJECT_SUCCESS env var for success emails
- Use EMAIL_SUBJECT_ERROR env var for error emails
- Provide safe defaults if env vars are missing or blank
- Add final guard in send_email() to prevent blank subjects

scraibe/email_sender.py

@@ -218,19 +218,20 @@ def send_email(
     if not to_list:
         raise EmailError("No valid 'To' email addresses provided.")
 
+    # Ensure subject is never blank
+    if not subject or not subject.strip():
+        logger.warning("Subject was blank or missing; using default subject.")
+        subject = "ScrAIbe: Your transcript is ready"
+
+    subject = subject.strip()
+
     # Build message
     msg = MIMEMultipart("alternative")
     msg["From"] = cfg["from_address"]
     msg["To"] = ", ".join(to_list)
     if cc_list:
         msg["Cc"] = ", ".join(cc_list)
-
-    # Ensure subject is never blank
-    if not subject or not subject.strip():
-        logger.warning("Subject was blank; using default subject.")
-        subject = "ScrAIbe: Your transcript is ready"
-
-    msg["Subject"] = subject.strip()
+    msg["Subject"] = subject
 
     # Attach plain text
     msg.attach(MIMEText(body, "plain"))
@@ -283,9 +284,10 @@ def send_email(
         )
         server.quit()
         logger.info(
-            "Email sent to %s (CC: %s)",
+            "Email sent to %s (CC: %s) with subject: %s",
             to_list,
             cc_list or "None",
+            subject,
         )
         return True
 
@@ -810,12 +812,20 @@ def send_success_email(
 ):
     """
     Send a success email with attachments.
+    Subject is customizable via EMAIL_SUBJECT_SUCCESS.
+    Falls back to a safe default if the env var is missing or blank.
     """
-    try:
-        cfg = get_email_config()
-    except EmailError as e:
-        logger.error("Email configuration error: %s", e)
-        raise
+    # Read subject from environment; never allow blank
+    raw_subject = os.getenv("EMAIL_SUBJECT_SUCCESS")
+    subject = (raw_subject or "").strip()
+
+    if not subject:
+        subject = "ScrAIbe: Your transcript is ready"
+        logger.info(
+            "EMAIL_SUBJECT_SUCCESS not set or blank; using default subject: %s", subject
+        )
+    else:
+        logger.info("Using EMAIL_SUBJECT_SUCCESS: %s", subject)
 
     # Build email body
     body = f"""
@@ -842,10 +852,10 @@ Please find the attached documents:
     except EmailError:
         html = None
 
-    # Send email
+    # Send email (send_email has an additional subject guard)
     send_email(
         to=to,
-        subject=f"Transcription Complete - Task {task_id}",
+        subject=subject,
         body=body,
         html=html,
         attachments=attachments,
@@ -859,12 +869,20 @@ def send_error_email(
 ):
     """
     Send an error email.
+    Subject is customizable via EMAIL_SUBJECT_ERROR.
+    Falls back to a safe default if the env var is missing or blank.
     """
-    try:
-        cfg = get_email_config()
-    except EmailError as e:
-        logger.error("Email configuration error: %s", e)
-        raise
+    # Read subject from environment; never allow blank
+    raw_subject = os.getenv("EMAIL_SUBJECT_ERROR")
+    subject = (raw_subject or "").strip()
+
+    if not subject:
+        subject = "ScrAIbe: Error with your transcription request"
+        logger.info(
+            "EMAIL_SUBJECT_ERROR not set or blank; using default subject: %s", subject
+        )
+    else:
+        logger.info("Using EMAIL_SUBJECT_ERROR: %s", subject)
 
     # Build email body
     body = f"""
@@ -884,10 +902,10 @@ Error: {error_message}
     except EmailError:
         html = None
 
-    # Send email
+    # Send email (send_email has an additional subject guard)
     send_email(
         to=to,
-        subject=f"Transcription Error - Task {task_id}",
+        subject=subject,
         body=body,
         html=html,
         attachments=[],