* Stop multi-file uploads from tripping the per-IP concurrency guard
The /api/upload concurrency check summed its condition over `files`, but the
condition didn't reference the loop variable — so it collapsed to len(files)
whenever the IP had any recent upload. A single multi-file batch sent right
after another upload therefore counted itself as N concurrent uploads and hit
max_concurrent_uploads (3), returning 429. The browser swallows the 429 (no
`files` in the body) and sends the chat with no attachments, so the model
"doesn't even see" them (issue #1346).
Count genuine recent upload events instead, via a pure count_recent_uploads()
helper, independent of the current batch's file count. save_upload still
enforces the per-minute sliding-window rate limit per file, so throttling is
preserved.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
* Also reconcile the per-minute upload rate limit with the batch cap
Follow-up within #1346: even after the concurrency-guard fix, a 6+ file batch
still failed because save_upload() counts each file against upload_rate_limit
(was 5/min) while the composer allows MAX_FILES=10 per batch — the reporter saw
"5 attachments work, 6 fail". Raise the per-minute file cap to 60 so a single
full batch (and a few of them) isn't self-rejected; burst abuse stays bounded by
max_concurrent_uploads. Add a real 6-file regression + a config guard that the
cap exceeds the frontend MAX_FILES.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
