feat: configurable upload file size limits via .env (#695)

* feat: make upload file size limits configurable via .env

Add UPLOAD_MAX_*_MB environment variables for documents, images, videos,
exercise assignment files, AI assistant documents, landing page images,
and media thumbnails. API presign routes validate file size server-side;
dashboard UI reads the same limits from layout data.

* chore: wire upload limit env vars through Docker compose and docs

Pass UPLOAD_MAX_*_MB from the root .env into api and dashboard containers
in both compose files, document them in .env.example and self-hosting guides.

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* docs: cross-link upload limits in README, Railway, Coolify, and Cloudflare guides

Co-authored-by: Rotimi Best <rotimi-best@users.noreply.github.com>

* fix: address PR review feedback on upload limits

- Restore 5 MB default for thumbnail uploads (edit-asset-dialog regression)
- Add getResolvedUploadLimits() fallback for Storybook/tests
- Cache core getUploadLimits() like the dashboard helper
- Document presign fileSize as advisory; allow zero-byte fileSize in schema
- Only send fileSize to presign when greater than zero

* docs: remove upload limits from Cloudflare setup guide

---------

packages/ui/src/custom/exercise-question/question-list.svelte

@@ -32,6 +32,7 @@
         maxSubmissionItems: contract.maxSubmissionItems,
         disabled: contract.disabled,
         labels: contract.labels,
+        platformMaxFileSizeMb: contract.platformMaxFileSizeMb,
         onImageUpload: contract.onImageUpload,
         onFileUpload: contract.onFileUpload,
         onVideoRecordingUpload: contract.onVideoRecordingUpload

packages/ui/src/custom/exercise-question/question-renderer.svelte

@@ -475,6 +475,7 @@
     maxSubmissionItems={contract.maxSubmissionItems}
     disabled={contract.disabled}
     labels={contract.labels}
+    platformMaxFileSizeMb={contract.platformMaxFileSizeMb}
     onImageUpload={contract.onImageUpload}
     onFileUpload={contract.onFileUpload}
     onVideoRecordingUpload={contract.onVideoRecordingUpload}

packages/ui/src/custom/exercise-question/renderers/file-upload-types.ts

@@ -1,4 +1,6 @@
-export const FILE_UPLOAD_MAX_SIZE_MB = 2;
+export const FILE_UPLOAD_DEFAULT_MAX_SIZE_MB = 2;
+/** @deprecated Use FILE_UPLOAD_DEFAULT_MAX_SIZE_MB */
+export const FILE_UPLOAD_MAX_SIZE_MB = FILE_UPLOAD_DEFAULT_MAX_SIZE_MB;
 
 export const FILE_UPLOAD_SUPPORTED_TYPES = [
   { value: 'application/pdf', label: 'PDF (.pdf)', aliases: ['pdf', '.pdf'] },
@@ -106,10 +108,25 @@ export function isFileTypeAllowed(file: File, acceptedTypes: string[]): boolean
 
 const BYTES_PER_MB = 1024 * 1024;
 
-export function isFileSizeAllowed(file: File, maxSizeMb: number | undefined | null): boolean {
-  const effectiveMaxMb = Math.min(
-    typeof maxSizeMb === 'number' && maxSizeMb > 0 ? maxSizeMb : FILE_UPLOAD_MAX_SIZE_MB,
-    FILE_UPLOAD_MAX_SIZE_MB
-  );
+export function resolveExerciseFileUploadMaxSizeMb(
+  questionMaxSizeMb: number | undefined | null,
+  platformMaxSizeMb: number = FILE_UPLOAD_DEFAULT_MAX_SIZE_MB
+): number {
+  const effectivePlatformMax =
+    typeof platformMaxSizeMb === 'number' && platformMaxSizeMb > 0
+      ? platformMaxSizeMb
+      : FILE_UPLOAD_DEFAULT_MAX_SIZE_MB;
+  const requestedMax =
+    typeof questionMaxSizeMb === 'number' && questionMaxSizeMb > 0 ? questionMaxSizeMb : effectivePlatformMax;
+
+  return Math.min(requestedMax, effectivePlatformMax);
+}
+
+export function isFileSizeAllowed(
+  file: File,
+  maxSizeMb: number | undefined | null,
+  platformMaxSizeMb: number = FILE_UPLOAD_DEFAULT_MAX_SIZE_MB
+): boolean {
+  const effectiveMaxMb = resolveExerciseFileUploadMaxSizeMb(maxSizeMb, platformMaxSizeMb);
   return file.size <= effectiveMaxMb * BYTES_PER_MB;
 }

packages/ui/src/custom/exercise-question/renderers/file-upload/edit.svelte

@@ -12,10 +12,17 @@
   import {
     FILE_UPLOAD_SUPPORTED_TYPES,
     formatAcceptedFileTypes,
-    normalizeAcceptedFileTypes
+    normalizeAcceptedFileTypes,
+    resolveExerciseFileUploadMaxSizeMb
   } from '../file-upload-types';
 
-  let { question, disabled = false, labels, onQuestionChange = () => {} }: ExerciseQuestionRendererProps = $props();
+  let {
+    question,
+    disabled = false,
+    labels,
+    platformMaxFileSizeMb,
+    onQuestionChange = () => {}
+  }: ExerciseQuestionRendererProps = $props();
   const label = (key: Parameters<typeof getExerciseQuestionLabel>[1], fallback = '') =>
     getExerciseQuestionLabel(labels, key, fallback);
   const acceptedTypes = $derived(normalizeAcceptedFileTypes(question.settings?.acceptedTypes));
@@ -41,17 +48,19 @@
     patchSettings({ acceptedTypes: nextAcceptedTypes });
   }
 
+  const platformMaxMb = $derived(resolveExerciseFileUploadMaxSizeMb(undefined, platformMaxFileSizeMb));
+
   const rawMaxSize = $derived(question.settings?.maxSizeMb as number | undefined);
   const maxSizeMb = $derived(
     typeof rawMaxSize === 'number' && !Number.isNaN(rawMaxSize) && rawMaxSize >= 0
-      ? String(Math.min(rawMaxSize, 2))
+      ? String(Math.min(rawMaxSize, platformMaxMb))
       : ''
   );
 
   $effect(() => {
     const raw = question.settings?.maxSizeMb as number | undefined;
-    if (typeof raw === 'number' && raw > 2) {
-      patchSettings({ maxSizeMb: 2 });
+    if (typeof raw === 'number' && raw > platformMaxMb) {
+      patchSettings({ maxSizeMb: platformMaxMb });
     }
   });
 
@@ -61,7 +70,7 @@
       patchSettings({ maxSizeMb: undefined });
       return;
     }
-    patchSettings({ maxSizeMb: Math.min(2, Math.max(0, num)) });
+    patchSettings({ maxSizeMb: Math.min(platformMaxMb, Math.max(0, num)) });
   }
 </script>
 
@@ -107,7 +116,7 @@
       <Input
         type="number"
         min="0"
-        max="2"
+        max={platformMaxMb}
         step="0.1"
         placeholder={label('file_upload.edit.max_size_placeholder')}
         value={maxSizeMb}

packages/ui/src/custom/exercise-question/renderers/file-upload/take.svelte

@@ -11,6 +11,7 @@
     answer = null,
     disabled = false,
     labels,
+    platformMaxFileSizeMb,
     onAnswerChange = () => {},
     onFileUpload
   }: ExerciseQuestionRendererProps = $props();
@@ -86,7 +87,7 @@
 
     if (!selectedFile) return;
     if (!isFileTypeAllowed(selectedFile, acceptedTypes)) return;
-    if (!isFileSizeAllowed(selectedFile, maxSizeMb)) return;
+    if (!isFileSizeAllowed(selectedFile, maxSizeMb, platformMaxFileSizeMb)) return;
 
     if (!onFileUpload) return;