Send tape jobs paced, and carry the manual grouping through

Print, preview, PDF and the redirect back all honour a groups= spec, so
a hand-built label survives printing instead of reverting to drawers.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Vunz4VLxAYDBnU5tLciLDC

app/routes/labels_tape.py

@@ -46,7 +46,15 @@ def printer_config():
     }
 
 
-def _options_query(options, labels):
+def _group_spec():
+    """
+    The manual grouping from the page: "1,2|3" means parts 1 and 2 share a
+    label and part 3 is on its own. Empty means "work it out from drawers".
+    """
+    return (request.values.get('groups') or '').strip()
+
+
+def _options_query(options, labels, group_spec=None):
     """
     The chosen options as query args, so a redirect back to the tape page
     comes back exactly as the user left it. Without this, printing bounced
@@ -65,6 +73,8 @@ def _options_query(options, labels):
         'align': options.align,
         'fields': options.fields,
     }
+    if group_spec:
+        query['groups'] = group_spec
     # Checkboxes: only present when on, which is what the parser expects.
     if options.rotate:
         query['rotate'] = '1'
@@ -115,13 +125,16 @@ def index():
         source, rotate_default=config['rotate'],
         size_default=config['size_mode'], tape_default=config['tape'])
 
-    plan = tape_printer.plan_groups(labels, options)
+    group_spec = _group_spec()
+    plan = tape_printer.plan_groups(labels, options, group_spec)
     tape = tape_printer.get_tape(options.tape)
 
     return render_template(
         'admin/labels/tape.html',
         labels=labels,
         plan=plan,
+        group_spec=tape_printer.spec_from_groups(
+            [item['labels'] for item in plan]),
         ids=','.join(str(l.id) for l in labels),
         options=options,
         tapes=tape_printer.TAPE_PRESETS,
@@ -235,15 +248,18 @@ def print_tape():
         except ipp_client.IPPError as exc:
             flash(f'Could not reach the printer: {exc}', 'danger')
             return redirect(url_for('tape.index',
-                                    **_options_query(options, labels)))
+                                    **_options_query(options, labels,
+                                                     _group_spec())))
     if not mime_type:
         flash('The printer did not offer a format LIM can produce. Use '
               'Download PDF instead.', 'warning')
         return redirect(url_for('tape.index',
-                                **_options_query(options, labels)))
+                                **_options_query(options, labels,
+                                                 _group_spec())))
 
     upload_folder = current_app.config['UPLOAD_FOLDER']
-    plan = tape_printer.plan_groups(labels, options)
+    group_spec = _group_spec()
+    plan = tape_printer.plan_groups(labels, options, group_spec)
 
     if options.is_fixed and not tape_printer.tape_fits_label(options.tape):
         flash(f'{tape_printer.LABEL_WIDTH_MM:.0f}mm labels need 50mm tape - '
@@ -261,8 +277,13 @@ def print_tape():
             document = tape_printer.image_to_bytes(image, mime_type)
             # copies is handled by repeating the job rather than the IPP
             # copies attribute: tape printers vary wildly in honouring it.
+            #
+            # Paced rather than fired in a burst: the VC-500W takes one job
+            # at a time and answers "busy" to anything arriving while the
+            # tape is still moving, so each job waits for the printer to go
+            # idle and retries while it is still working.
             for _ in range(options.copies):
-                ipp_client.print_job(
+                ipp_client.print_job_paced(
                     host, document, mime_type,
                     job_name=f'LIM: {name}'[:120],
                     port=config['port'], path=config['path'])
@@ -279,7 +300,8 @@ def print_tape():
     for problem in failures[:5]:
         flash(problem, 'danger')
 
-    return redirect(url_for('tape.index', **_options_query(options, labels)))
+    return redirect(url_for('tape.index',
+                            **_options_query(options, labels, group_spec)))
 
 
 @tape_bp.route('/download.pdf', methods=['GET', 'POST'])
@@ -298,7 +320,7 @@ def download_pdf():
         source, rotate_default=config['rotate'],
         size_default=config['size_mode'], tape_default=config['tape'])
     buffer = tape_printer.render_batch_pdf(
-        labels, options, current_app.config['UPLOAD_FOLDER'])
+        labels, options, current_app.config['UPLOAD_FOLDER'], _group_spec())
     if buffer is None:
         flash('Nothing to render.', 'warning')
         return redirect(url_for('labels.index'))