Second item of the v1.0.6 backlog. The "front 500MB vs back 100MB" mismatch
flagged in the v1.0.5 audit turned out to be a misread — every live pair
was already aligned (tracks 100/100, cloud 500/500, video 500/500). The
real bug is architectural: the same byte values were duplicated in five
places (`track/service.go`, `handlers/upload.go:GetUploadLimits`,
`handlers/education_handler.go`, `upload-modal/constants.ts`, and
`CloudUploadModal.tsx`), drifting silently as soon as anyone tuned one.
Backend — one canonical spec at `internal/config/upload_limits.go`:
* `AudioLimit`, `ImageLimit`, `VideoLimit` expose `Bytes()`, `MB()`,
`HumanReadable()`, `AllowedMIMEs` — read lazily from env
(`MAX_UPLOAD_AUDIO_MB`, `MAX_UPLOAD_IMAGE_MB`, `MAX_UPLOAD_VIDEO_MB`)
with defaults 100/10/500.
* Invalid / negative / zero env values fall back to the default;
unreadable config can't turn the limit off silently.
* `track.Service.maxFileSize`, `track_upload_handler.go` error string,
`education_handler.go` video gate, and `upload.go:GetUploadLimits`
all read from this single source. Changing `MAX_UPLOAD_AUDIO_MB`
retunes every path at once.
Frontend — new `useUploadLimits()` hook:
* Fetches GET `/api/v1/upload/limits` via react-query (5 min stale,
30 min gc), one retry, then silently falls back to baked-in
defaults that match the backend compile-time defaults so the
dropzone stays responsive even without the network round-trip.
* `useUploadModal.ts` replaces its hardcoded `MAX_FILE_SIZE`
constant with `useUploadLimits().audio.maxBytes`, and surfaces
`audioMaxHuman` up to `UploadModal` → `UploadModalDropzone` so
the "max 100 MB" label and the "too large" error toast both
display the live value.
* `MAX_FILE_SIZE` constant kept as pure fallback for pre-network
render (documented as such).
Tests
* 4 Go tests on `config.UploadLimit` (defaults, env override, invalid
env → fallback, non-empty MIME lists).
* 4 Vitest tests on `useUploadLimits` (sync fallback on first render,
typed mapping from server payload, partial-payload falls back
per-category, network failure keeps fallback).
* Existing `trackUpload.integration.test.tsx` (11 cases) still green.
Out of scope (tracked for later):
* `CloudUploadModal.tsx` still has its own 500MB hardcoded — cloud
uploads accept audio+zip+midi with a different category semantic
than the three in `/upload/limits`. Unifying those deserves its
own design pass, not a drive-by.
* No runtime refactor of admin-provided custom category limits —
the current tri-category split covers every upload we ship today.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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