The document matcher decided by extension and fell through to "decode whatever
this is as UTF-8" for everything that was not a .pdf. A shell script, an HTML
page, a CSV or a JPEG all became a search query, and a file called report.pdf
holding something else was read as a PDF.
Three questions now, in order, before anything else touches the file: is it
under 2 MB (read one byte past the cap, so a huge file is never held in memory
to be measured); what is it, sniffed from the leading bytes; and what text is
in it. PDF, DOCX and images, and nothing else — 415 with a sentence naming what
to upload instead. DOCX is parsed from the zip with no new dependency and is
checked against the one attack that shape allows, a member that unpacks to far
more than the file's size suggests. An image is read by the tool model, and
where no tool model is configured it says so rather than 500ing.
On injection, since that is the question people mean: there is no path from an
uploaded file to code that runs. The extracted text is a search query — bound
parameter to Postgres, never concatenated into SQL — and the content of a
message to a model. It is never rendered as HTML, never written to disk, never
passed to a shell. Control characters are stripped because they make queries
that match nothing, not because anything would interpret them.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TqXevQJhxFrM7jJg82cgZN
