[davior]

Why

GVC asked GAM for a picture by aspect alone:

• FLUX made 1024×576 for a 1080p video.
• Nano Banana used its 1K default.
• Seedream got no size at all.

The result was about half the frame's width, and softer still once a Ken Burns zoom or an S1 crop reads into part of it.

What

• Target. target_size(aspect, resolution) is the output frame (render/options.frame_size) × PICTURE_HEADROOM = 1.5, in the placeholder's own aspect. A 1080p 16:9 video targets 2880×1620; a 1:1 picture in it targets 1620×1620.
• Choosing the size in default_params(…, target=):

  1. A model with custom_size (GAM-8, davior/gam#53) gets width/height. If the target is over the model's limits, it is shrunk with the aspect kept and rounded to the model's multiple. FLUX at 1080p asks for 2880×1616.

  2. A model with size tiers (Nano Banana's 0.5K…4K, Seedream's auto_2K/4K) gets the tier nearest the target by ratio, but never one smaller than the frame while a larger one exists:

     • 1080p gets 2K (1.43× the frame).
     • 4K gets 4K.
     • 720p gets 1K, which is still above the frame.

     "Smallest at or above 1.5×" would have sent every 1080p picture to 4K.

  3. Otherwise behave as before. Against a GAM without GAM-8, FLUX keeps its preset.

• Clips are unchanged, including the picture made for a clip from a prompt. That's out of scope for now.
• Estimate. Megapixel pricing uses the custom size and counts fal's whole 1024² megapixels, which is how GAM is billed.
  • FLUX schnell at 2880×1616 is 5 MP, $0.015.
  • FLUX dev at that size is about $0.125 per picture.
• Docs. GAM-8 is added to the plan's "Changes needed in GAM".

Tests

• pytest -q: 755 passed. Covers target sizes, custom-size clamping, tier choice and the never-below-the-frame rule, Seedream's auto sizes, the old-GAM fallback, the estimate, and HTTP paths through the fake GAM.
• npm test: 192 passed. npm run build: clean. No frontend change.

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