razbakov/event-flyer-pack

Event Flyer Pack

One event → one set of Gemini prompts → five deliverables, each with a real scannable QR. The pack is the standard composition of image-from-gemini (each full asset, fully typeset by Gemini) + qr-code-generator (one real QR) + a minimal overlay step that replaces Gemini's drawn QR placeholder with the real one.

Core workflow discovered on 2026-04-17 (Frida Cubana build): Gemini renders gorgeous print assets with baked-in typography, but it cannot render a scannable QR — it produces decorative squares that look like QRs but do not encode anything. The fix is not to build a layout engine in Pillow, it's to let Gemini do the design and swap the fake QR for a real one.

Trigger

Use when the user:

• Has a specific upcoming event (date, venue, entry, URL) and needs printed promo by a deadline.
• Asks for "flyers + QR," "table card for my gig," "promo pack," "ambience DJ set with my own promo," "party this weekend print material," etc.
• Says something like "I need flyers for <event> tomorrow / next week".

Do not use this skill for: brand-only cards (use brand-poster), single-channel IG graphics (use image-from-gemini), pure QR codes (use qr-code-generator).

Deliverables (standard set)

| File | Size / aspect | Purpose | |---|---|---| | <slug>-flyer-front.png | A6 portrait (2:3), upscaled to 300 DPI | Vendor print master — front | | <slug>-flyer-back.png | A6 portrait | Vendor print master — back | | <slug>-flyer-a4-4up-front.pdf | A4 | Home printable 4-up + crop marks | | <slug>-flyer-a4-4up-back.pdf | A4 | Home printable 4-up + crop marks | | <slug>-tent-card.png | A6 portrait, top half mirrored 180° | DJ booth / bar table tent | | <slug>-instagram-story.jpg | 1080×1920 | IG story / WhatsApp status |

All printed assets target 300 DPI at A6 (1240×1748 px). Gemini outputs typically come at ~1024–2048 px on the long edge — upscale via sips or PIL resample before export if print sharpness matters.

Required inputs

• Event slug — short filename prefix (e.g. frida-cubana).
• Event title (one or two lines).
• Date in the event's language + time window + venue + entry price.
• Event URL — the single URL encoded into every QR. Keep short (< 50 chars) so the QR stays readable at 18 mm print.
• Style / program line (optional — "Timba · Son · Rumba Cubana").
• Highlights (optional — for the back: "Free shot", "Domino table").
• Dresscode / pull quote (optional, 1 line).
• DJ / host name (optional).
• Brand language — what aesthetic Gemini should render (e.g. "warm Cuban editorial", "90s rave poster", "minimalist Scandinavian").
• Language — copy language (de, en, es, ru).
• Output directory — local path for the generated files.

Process

For each of the 5 asset types, execute the same 3-step recipe:

Step 1 — Generate the full asset with Gemini

Invoke skill image-from-gemini with a prompt that includes:

• Full event copy (title, date, venue, entry, program, dresscode, DJ).
• Target aspect ratio (2:3 portrait for A6, 9:16 for IG story, tent card has two mirrored halves).
• Brand aesthetic.
• Explicit QR placeholder instruction: "leave a clean solid-white square, roughly 20–25% of the short edge, in the {bottom-center | bottom-right | specified area} of the design, for a QR code overlay. Do not render a QR pattern — leave the square empty white."

Prompt templates per asset: see assets/templates/gemini_prompts.md.

Step 2 — Generate the real QR

Invoke skill qr-code-generator with:

• the event URL
• error correction H
• black on white
• size: aim for target_qr_side_px = short_edge_px * 0.22 (roughly 20–24 mm at print scale for A6; ~360 px for IG story)

Step 3 — Composite the QR over Gemini's placeholder

Detect the white placeholder square in the Gemini output (either by eye + manual coordinates, or by simple color-threshold detection — see scripts/overlay_qr.py). Paste the QR there, preserving a small white quiet-zone margin (≥ QR/18) around it.

Verify the composite scans — reload the output PNG with any QR detector (OpenCV's QRCodeDetector, pyzbar, or a phone) and assert the decoded URL matches the event URL. For multi-QR sheets (A4 4-up, tent card with mirrored halves), crop each QR region and test individually — single-code detectors return "NO DECODE" when two identical codes share one frame.

See qr-code-generator's "Embedding QR codes inside a larger composition" section for the full embedding checklist.

Hard-learned rules (from the Frida Cubana build)

1. Gemini will draw a fake QR even if you ask it not to. It renders something that looks like a QR — black-and-white modules in a square — but it encodes nothing. Always overlay a real one. This is the entire reason this skill exists.
2. Tell Gemini exactly where the placeholder goes. Ambiguous instructions ("include a QR") → the fake QR ends up in random positions across retries, making overlay coordinates non-reproducible. Pin it: "in the bottom center, 20% from the bottom edge, a 200×200 px pure-white square."
3. Shorten URLs before generating. A URL over ~50 chars forces a denser QR grid; below 18 mm print it stops scanning. Use a short event URL (e.g. wedance.vip/events/<id>), not a full UTM-laden campaign link — put UTMs on the landing page.
4. One event ≠ one Gemini call. Each asset (flyer front, back, tent, IG story) is a separate prompt. They share copy and aesthetic but differ in aspect ratio and emphasis. Don't try to make Gemini output all 5 in one go.
5. Generate 2 variants per asset, pick one. Gemini's compositional variance is high — the second attempt is often dramatically better. Budget 10–15 seconds per retry.
6. For the tent card, generate each half separately (wine-red top, navy bottom, both with the same copy), then mirror the top 180° and stack. Gemini cannot reliably render a single image with one half rotated.

Output format (required when reporting back)

• 5–6 files produced with local paths.
• QR verification results per asset (expected URL + pass/fail).
• Per-asset note: which Gemini variant was picked and why.
• Delivery checklist (see assets/templates/delivery_checklist.md).

Bundled assets

• assets/templates/gemini_prompts.md — prompt templates for flyer front, flyer back, tent card halves, IG story. Each has {placeholders} that the caller fills in from the event spec.
• assets/templates/event_spec_example.json — the Frida Cubana inputs as a concrete example.
• assets/templates/gemini_hero_prompt.md — historical reference; skip unless generating a hero-only asset.
• assets/templates/delivery_checklist.md — what to print, how many, where to place.
• scripts/overlay_qr.py — thin helper that takes a Gemini output PNG + a QR PNG + placeholder coordinates (or auto-detect) and writes the composite. ~40 lines. Deliberately minimal — this skill does not own layout, Gemini does.

Delegation

• Hero / full asset art → image-from-gemini (5 calls, one per asset).
• QR code → qr-code-generator (1 call, reused across all 5 composites).
• Brand-wide style decisions (palette, typography voice) → brand-poster if the event doesn't yet have a visual language.