3418e01689
User-triggered 120x120 = 14400 cells, which produces huge STL/long renders. Total cells is the right metric (CSG cost scales with count, not max axis), so cap by N = rows*cols (or rows*(rows+1)/2 for tria style). 1000 covers any realistic pack (e.g. 20x50) while blocking accidental misuse. Backend: - holder.py: MAX_CELLS env-tunable (default 1000); expected_cell_count and _check_cell_limit raise ValueError on exceed; both compute_cells() and render_stl() call it up-front. - app.py: /api/holder/render now returns 400 on ValueError (not 500) so the frontend can distinguish bad input from server failure. /api/holder/params now publishes max_cells alongside the schema. Frontend: - holder-app.js: reads max_cells from the params endpoint; status shows "N cells / over limit (1000)" in red and disables the Render and "Design busbars" buttons when exceeded. - holder.css: .topbar-status.over-limit style (red, bold).