3 min read
The AI prompt
This is the block you paste into your AI chat before you describe your app. It
teaches the assistant GDN's rules — the panel size, that fonts are uppercase-only,
how http.get works — so it writes real GDN code instead of guessing from another
platform.
Use it once at the start of a chat. After it, describe your app in a sentence or two, and the AI has the context it needs.
You are writing an app for the Glance Developer Network (GDN): an app that renders
to a Glance LED panel. The panel is always 32 pixels tall. Each panel module is
64 pixels wide and panels daisy-chain up to 384 pixels wide; for best performance keep
images to 192x32 or smaller and split content across multiple pages. An app is a FOLDER
with two files:
manifest.yaml - settings: id, name, width, height, refresh (seconds),
pages: [list of screen names], and inputs (the user's form).
app.star - Starlark (Python-like) code. Define ONE function per page:
def <page>(c, ctx): ... It DRAWS a picture; it never returns
anything. c = the canvas, ctx.inputs = the user's values,
ctx.now = the current time (UTC).
Coordinates: (0,0) is top-left, x grows right, y grows down. For text and images,
(x, y) is the TOP-LEFT corner. Circles/dots center on their coordinates.
Drawing (c.*):
fill(color) / clear() ; pixel(x,y,color) ; rect(x0,y0,x1,y1,fill=,outline=)
line(x0,y0,x1,y1,color) ; text(s,x,y,font="5x7",color="white",align="left")
image("file.png",x,y,w=,h=) ; bitmap([[0,1,...],...],x,y,color)
Helpers (composites, prefer these): circle, fill_circle, round_rect, hline, vline,
gradient_rect, text_center, text_right, text_wrapped, text_fit,
progress_bar, sparkline, bars, badge, trend_arrow, icon("sun"), sprite,
header, kv, stat, gauge, status_dot, table, scoreboard, grid, color.dim.
Colors: names ("green","amber","red","white",...) or hex ("#00FF00").
Fonts: "4x5","5x7","6x8","7x12","16x24", etc.
HARD RULES:
- Fonts are UPPERCASE ONLY. Call .upper() on any text, or nothing draws.
- Frames are STILL IMAGES. Don't animate or scroll; the panel re-renders on the
manifest's `refresh` timer, so let the next refresh show new data.
- Draw immediately with c.*; there is no widget tree and you never return anything.
- Lay things out by hand; the panel is only 32px tall, so keep text short.
- To fetch live data, call http.get(url, headers={}, params={}, ttl_seconds=300).
It returns a DICT you read with SUBSCRIPTS: resp["status_code"], resp["json"],
resp["body"]. NOT resp.status_code — Starlark dicts have no attribute access, so
the dotted form errors. ALWAYS check resp["status_code"] == 200 before resp["json"].
- Read inputs with ctx.inputs.get("key", fallback). Declare each input in the
manifest with app_input_type: free-text|api-key|dropdown|checkbox|date|date-past|color|selection.
- API keys MUST use app_input_type: api-key, never free-text. Only api-key inputs
are stored encrypted; a key given as free text may not work. The input name of
an api-key MUST NOT contain _ or - (use "apikey", never "api_key" or "api-key");
validation rejects api-key input names containing them.
Give me BOTH files, complete. Keep text short and high-contrast.
Paste it once per chat
You only need to send this at the start of a conversation. From there, keep describing changes in plain English and the AI already knows the rules. If a chat drifts and the AI starts breaking them (lowercase text, animations), paste it again to re-anchor.