How pxpipe sizes rendered images

Image geometry is selected by the exact model id. /v1/responses is only a wire protocol: Claude, GPT, and Grok on that path do not share a renderer.

Current behavior

A page is profile-width and variable-height. It is never padded to a square.

cellWidth  = atlasWidth  + cellWBonus
cellHeight = atlasHeight + cellHBonus
width      = 2 * PAD_X + columns * cellWidth
height     = 2 * PAD_Y + usedRows * cellHeight

Width may shrink to the widest rendered line, capped by the profile. Height grows with content until the profile cap, then overflow becomes another page.

model rule	atlas / effective cell	columns	full width	max height
Claude / Anthropic	Spleen + Unifont, 5×8	312	1568 px	728 px
opt-in `gpt-5.6-sol`	Spleen + Unifont, 5×8	152	768 px	1932 px
opt-in Grok 4.5	Spleen + Unifont, 5×8 white AA + IDS + factsheet (no grid)	152	768 px	512 px
other OpenAI fallback	Spleen + Unifont, 5×8	152	768 px	1932 px

Complete profile values and evidence are in MODEL_RENDER_PROFILES.md.

The Sol row is the currently configured geometry, not a successful recall claim. Paid raw-image calls tested both the earlier 6×11/126-column geometry and this 5×8/152-column profile: each returned 0/4 exact identifiers with four confabulations; 5×8 also missed gist. Sol is consequently opt-in. The effective 9×12/84-column Sol candidate is local-only pending a model call. See eval/sol-profile/RESULTS.md.

Provider boundaries

Anthropic resizes images to fit both a 1568px long edge and roughly 1.15MP. The 1568×728 Claude page stays inside both bounds, so rasterized glyphs reach the vision encoder without the old 0.555× resample.

OpenAI-shaped profiles use portrait strips at or below the 768px short-side floor. GPT 5.6 Sol and Grok both use 152×5+8, a 768px strip (1932 px and 512 px tall respectively).

Font and Unicode

Atlases are generated at build time; runtime never loads font files. The compact JetBrains atlas contains common code/Latin/symbol ranges. Missing codepoints fall back to the full Spleen/Unifont atlas, preserving multilingual rendering.

Spacing, anti-aliasing, grid, color cycle, and newline-marker style are all part of the model profile. The same style object is used for static slabs and history.

Gate parity

The profitability gate resolves the same profile as the renderer and derives:

cell width and height
content-width shrink
rows per page
page count
per-image token cost

Changing cell spacing or font therefore cannot leave cost prediction on a hardcoded 5×8 canvas. Claude uses the Anthropic pixel formula with a conservative margin, GPT uses model-specific tile/patch pricing, and Grok uses the measured tokens-per-megapixel rate.

Why not square pages

Billing follows pixel area or patches/tiles, not visual symmetry. Padding a portrait or short final page to a square adds cost without adding information. The target is readable characters per billed pixel under each provider's resize contract, not a preferred aspect ratio.

Measurement history

date	change	finding
2026-05-21	R3 reflow	recovered line-end dead space by marking hard newlines with `↵`
2026-05-22	grayscale atlas + L1/L2 harness	measured style and instruction-band effects
2026-06-09	Fable-only 5×8 scope	Fable read dense cells better than Opus
2026-06-17	~1932px experiment	fewer pages, later shown to be server-resampled on Anthropic
2026-07-01	Claude 1568×728 clamp	made billed pixels survive Anthropic preprocessing
2026-07-09	exact-model profiles	separated Claude, GPT 5.6 Sol, and Grok geometry/style
2026-07-11	Grok profile	Shared 5×8 + IDS + factsheet production stack; Grok opt-in only
2026-07-11	default scope	Fable only; Sol and Grok remain opt-in after broader quality tests

Older benchmark receipts retain their historical geometry; do not rewrite those numbers as if they were generated by the current profile.

Changing a profile

Add or re-run a reader-specific recall/style harness.
Measure the provider's real image-token accounting.
Keep the strip inside its no-resize boundary.
Test slab, history, gate, and cache determinism together.
Do not generalize one variant's result to sibling model ids.

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