`POST /api/downloads/upload` declared `file: UploadFile = File(...)`, and
FastAPI parses and spools a declared body before the first dependency runs --
`require_human` included. An unauthenticated caller could therefore make the
process write the whole per-file allowance (500 MiB by default) to temp, once
per request. SEC-20's ceiling bounded that number but could not stop the
writing, which is why E27 parked it rather than closing it.
The route now takes no body parameter. `spool_upload` names `require_human`
first and only then streams `request.stream()` to the staging temp file, so a
stranger is refused before a byte moves -- the shape the screenshot route has
used since E16. Filename and display name travel as percent-encoded headers
(latin-1 on the wire, so a Hungarian filename needs the encoding) instead of
multipart parts.
`capped_stream_to` joins `capped_body` in routes/_common.py: the same counting
rule, written to a file descriptor rather than accumulated, because holding
500 MiB would trade a disk problem for a memory one. Its refusal is the
caller's, so the upload route keeps answering 422 `upload_too_large` with the
admin knob's own number.
With no envelope to allow for, the edge is now exactly that knob, and
MULTIPART_ENVELOPE_ALLOWANCE is gone.
The invariant stops being prose: test_body_limit.py asks FastAPI itself
(`route.dependant.body_params`) and fails the gate if any route with a raised
ceiling declares a body. A comment could not have prevented the defect it
described; that test would have.
Both new tests were seen red for the right reason -- before the fix the
anonymous probe got its 401 only after the server had read 4236 bytes of a
multipart body, and re-declaring the File parameter turns the invariant test
red naming the route and the parameter.
peter
f5018bdcbc