Add admin-configurable upload size limits

The 8MB image/file/avatar cap is now a site setting (UploadSettings,
single-row table like SmtpSettings) editable from the Admin Settings tab,
instead of a hardcoded constant. All three upload endpoints read the live
value and interpolate it into their 413 messages. A new GET
/api/uploads/limit endpoint (open to any authenticated user, unlike the
admin-only settings endpoints) lets the composer reject an oversized file
client-side before it ever hits the network, though the server still
enforces the same cap independently.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/README.md

@@ -1,4 +1,4 @@
-# KeepItTalking backend (Phase 1 + 2 + 4 + 5 + 6 + 7 + 8, image uploads, file attachments, emoji & reactions, user profiles, site invites & email, password reset)
+# KeepItTalking backend (Phase 1 + 2 + 4 + 5 + 6 + 7 + 8, image uploads, file attachments, admin-configurable upload size limits, emoji & reactions, user profiles, site invites & email, password reset)
 
 FastAPI + SQLAlchemy 2.0 (async) + PostgreSQL + Redis. Implements auth, room
 CRUD (open and private), room roles (owner/admin/member) and direct
@@ -398,6 +398,34 @@ share them; `ImageTooLargeError` was likewise renamed to
 
 Same orphaned-upload disk-space caveat as images applies here too.
 
+## Upload size limits
+
+The 8 MB image/file/avatar cap is no longer hardcoded — it's an
+admin-configurable site setting (`UploadSettings`, single-row table, same
+"fetch-or-create" convention as `SmtpSettings`), editable from the Admin
+portal's Settings tab. Unlike `SmtpSettings` (where "no row yet" means
+"unconfigured, skip"), a missing row here still needs a usable value, so
+`upload_settings_service.get_upload_settings` creates it with the 8 MB
+default (`storage.DEFAULT_MAX_UPLOAD_BYTES`) on first read instead of
+returning `None`.
+
+- `GET`/`PUT /api/admin/settings/uploads` (site-admin only) — read/update
+  the cap. Bounds-checked to 1–500 MB (`UploadSettingsUpdate`) to guard
+  against a fat-fingered 0 or an unbounded figure that could exhaust disk.
+- `GET /api/uploads/limit` — unlike the admin endpoints, this one is open
+  to any authenticated user (same `Depends(get_current_user)`-only pattern
+  as `/api/push/vapid-public-key`), since every room member needs to know
+  the cap, not just admins. The frontend composer fetches it once per
+  mount and rejects an oversized file client-side before ever hitting the
+  network; the server still enforces the same value independently via
+  `read_capped(file, cap=...)`, so the client-side check is a UX nicety,
+  not the actual security boundary.
+- All three upload endpoints (room image, room file, avatar) now call
+  `get_upload_settings(db)` and pass the live value into `read_capped`
+  instead of relying on a module-level constant; their 413 error messages
+  interpolate the actual configured limit (`upload_settings_service.
+  format_mb`) rather than a hardcoded "8 MB" string.
+
 ## Emoji & reactions
 
 An emoji picker in the frontend composer is purely client-side (a static

backend/alembic/versions/880f080648de_upload_settings.py

@@ -0,0 +1,37 @@
+"""upload settings
+
+Revision ID: 880f080648de
+Revises: 5b1a142dc271
+Create Date: 2026-08-15 20:35:19.357542
+
+"""
+from typing import Sequence, Union
+
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision: str = '880f080648de'
+down_revision: Union[str, Sequence[str], None] = '5b1a142dc271'
+branch_labels: Union[str, Sequence[str], None] = None
+depends_on: Union[str, Sequence[str], None] = None
+
+
+def upgrade() -> None:
+    """Upgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table('upload_settings',
+    sa.Column('id', sa.Uuid(), nullable=False),
+    sa.Column('max_upload_bytes', sa.BigInteger(), nullable=False),
+    sa.Column('updated_at', sa.DateTime(timezone=True), server_default=sa.text('now()'), nullable=False),
+    sa.PrimaryKeyConstraint('id')
+    )
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    """Downgrade schema."""
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_table('upload_settings')
+    # ### end Alembic commands ###

backend/app/main.py

@@ -11,7 +11,7 @@ from redis.asyncio import Redis
 from starlette.middleware.sessions import SessionMiddleware
 
 from app.config import settings
-from app.routers import admin, auth, bots, health, push, rooms, signup, users, webhooks
+from app.routers import admin, auth, bots, health, push, rooms, signup, uploads, users, webhooks
 from app.ws.broadcaster import RoomBroadcaster
 from app.ws.chat import router as ws_router
 from app.ws.connection_manager import ConnectionManager
@@ -76,6 +76,7 @@ def create_app() -> FastAPI:
     app.include_router(rooms.router)
     app.include_router(users.router)
     app.include_router(push.router)
+    app.include_router(uploads.router)
     app.include_router(admin.router)
     app.include_router(bots.router)
     app.include_router(webhooks.router)

backend/app/models/__init__.py

@@ -13,6 +13,7 @@ from app.models.push_subscription import PushSubscription
 from app.models.room import Room
 from app.models.site_invite import SiteInvite
 from app.models.smtp_settings import SmtpSettings
+from app.models.upload_settings import UploadSettings
 from app.models.user import User
 from app.models.webhook_incoming import WebhookIncoming
 
@@ -30,6 +31,7 @@ __all__ = [
     "PasswordReset",
     "SiteInvite",
     "SmtpSettings",
+    "UploadSettings",
     "PushSubscription",
     "AdminAuditLog",
     "ApiToken",

backend/app/models/upload_settings.py

@@ -0,0 +1,21 @@
+import uuid
+from datetime import datetime
+
+from sqlalchemy import BigInteger, DateTime, func
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.models.base import Base
+
+
+class UploadSettings(Base):
+    """A single-row table (enforced in the service layer, not the schema --
+    same convention as SmtpSettings) holding the site-wide max upload size
+    for images and file attachments, set through the Admin UI."""
+
+    __tablename__ = "upload_settings"
+
+    id: Mapped[uuid.UUID] = mapped_column(primary_key=True, default=uuid.uuid4)
+    max_upload_bytes: Mapped[int] = mapped_column(BigInteger, nullable=False)
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime(timezone=True), server_default=func.now(), onupdate=func.now(), nullable=False
+    )

backend/app/routers/admin.py

@@ -16,6 +16,7 @@ from app.schemas.admin import (
 )
 from app.schemas.site_invite import SiteInviteCreate, SiteInviteRead
 from app.schemas.smtp_settings import SmtpSettingsRead, SmtpSettingsUpdate
+from app.schemas.upload_settings import UploadSettingsRead, UploadSettingsUpdate
 from app.schemas.webhook import EventSubscriptionAdminRead, WebhookIncomingAdminRead
 from app.services.admin_service import (
     CannotActOnSelfError,
@@ -40,6 +41,7 @@ from app.services.site_invite_service import (
     revoke_site_invite,
 )
 from app.services.smtp_settings_service import get_smtp_settings, upsert_smtp_settings
+from app.services.upload_settings_service import get_upload_settings, update_upload_settings
 from app.services.webhook_service import (
     list_all_event_subscriptions_admin,
     list_all_incoming_webhooks_admin,
@@ -379,3 +381,24 @@ async def test_smtp_settings_endpoint(
         raise HTTPException(status_code=400, detail="SMTP is not configured yet")
     except Exception as exc:
         raise HTTPException(status_code=502, detail=f"Failed to send test email: {exc}")
+
+
+@router.get("/settings/uploads", response_model=UploadSettingsRead)
+async def get_upload_settings_endpoint(
+    current_user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    require_site_admin(current_user)
+    cfg = await get_upload_settings(db)
+    return UploadSettingsRead(max_upload_bytes=cfg.max_upload_bytes, updated_at=cfg.updated_at)
+
+
+@router.put("/settings/uploads", response_model=UploadSettingsRead)
+async def update_upload_settings_endpoint(
+    data: UploadSettingsUpdate,
+    current_user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    require_site_admin(current_user)
+    cfg = await update_upload_settings(db, max_upload_bytes=data.max_upload_bytes)
+    return UploadSettingsRead(max_upload_bytes=cfg.max_upload_bytes, updated_at=cfg.updated_at)

backend/app/routers/auth.py

@@ -20,6 +20,7 @@ from app.services.password_service import (
     request_password_reset,
     validate_reset_token,
 )
+from app.services.upload_settings_service import format_mb, get_upload_settings
 from app.storage import (
     ALLOWED_IMAGE_CONTENT_TYPES,
     InvalidImageError,
@@ -89,10 +90,14 @@ async def upload_avatar(
     if file.content_type not in ALLOWED_IMAGE_CONTENT_TYPES:
         raise HTTPException(status_code=400, detail="Unsupported image type")
 
+    upload_settings = await get_upload_settings(db)
     try:
-        data = await read_capped(file)
+        data = await read_capped(file, cap=upload_settings.max_upload_bytes)
     except UploadTooLargeError:
-        raise HTTPException(status_code=413, detail="Image exceeds 8 MB limit")
+        raise HTTPException(
+            status_code=413,
+            detail=f"Image exceeds {format_mb(upload_settings.max_upload_bytes)} limit",
+        )
 
     try:
         data, ext = process_image(

backend/app/routers/rooms.py

@@ -35,6 +35,7 @@ from app.schemas.webhook import (
     WebhookIncomingRead,
 )
 from app.services.message_service import get_reactions_for_messages, list_recent_messages
+from app.services.upload_settings_service import format_mb, get_upload_settings
 from app.services.room_service import (
     AlreadyMemberError,
     CannotRemoveOwnerError,
@@ -73,7 +74,6 @@ from app.services.webhook_service import (
 from app.services.ssrf import UnsafeWebhookUrlError
 from app.storage import (
     ALLOWED_IMAGE_CONTENT_TYPES,
-    MAX_FILE_BYTES,
     UPLOADS_DIR,
     InvalidImageError,
     UploadTooLargeError,
@@ -337,10 +337,14 @@ async def upload_room_image_endpoint(
     if file.content_type not in ALLOWED_IMAGE_CONTENT_TYPES:
         raise HTTPException(status_code=400, detail="Unsupported image type")
 
+    upload_settings = await get_upload_settings(db)
     try:
-        data = await read_capped(file)
+        data = await read_capped(file, cap=upload_settings.max_upload_bytes)
     except UploadTooLargeError:
-        raise HTTPException(status_code=413, detail="Image exceeds 8 MB limit")
+        raise HTTPException(
+            status_code=413,
+            detail=f"Image exceeds {format_mb(upload_settings.max_upload_bytes)} limit",
+        )
 
     try:
         data, ext = process_image(data, file.content_type)
@@ -388,10 +392,14 @@ async def upload_room_file_endpoint(
 ):
     await require_room_member(room_id, current_user, db)
 
+    upload_settings = await get_upload_settings(db)
     try:
-        data = await read_capped(file, cap=MAX_FILE_BYTES)
+        data = await read_capped(file, cap=upload_settings.max_upload_bytes)
     except UploadTooLargeError:
-        raise HTTPException(status_code=413, detail="File exceeds 8 MB limit")
+        raise HTTPException(
+            status_code=413,
+            detail=f"File exceeds {format_mb(upload_settings.max_upload_bytes)} limit",
+        )
 
     original_filename = file.filename or "file"
     ext = pathlib.Path(original_filename).suffix

backend/app/routers/uploads.py

@@ -0,0 +1,22 @@
+from fastapi import APIRouter, Depends
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.database import get_db
+from app.dependencies import get_current_user
+from app.models import User
+from app.schemas.upload_settings import UploadSettingsRead
+from app.services.upload_settings_service import get_upload_settings
+
+router = APIRouter(prefix="/api/uploads", tags=["uploads"])
+
+
+@router.get("/limit", response_model=UploadSettingsRead)
+async def get_upload_limit_endpoint(
+    current_user: User = Depends(get_current_user),
+    db: AsyncSession = Depends(get_db),
+):
+    """Any authenticated user (not just site admins -- unlike
+    /api/admin/settings/uploads) can read the current cap, so the composer
+    can validate client-side before uploading."""
+    cfg = await get_upload_settings(db)
+    return UploadSettingsRead(max_upload_bytes=cfg.max_upload_bytes, updated_at=cfg.updated_at)

backend/app/schemas/upload_settings.py

@@ -0,0 +1,16 @@
+from datetime import datetime
+
+from pydantic import BaseModel, Field
+
+
+class UploadSettingsRead(BaseModel):
+    max_upload_bytes: int
+    updated_at: datetime
+
+
+class UploadSettingsUpdate(BaseModel):
+    # Guardrails against a fat-fingered 0/negative value or an unbounded
+    # figure that could exhaust disk -- 1 MB to 500 MB is generous enough
+    # for any real attachment while still being a sane range to type into
+    # a number input.
+    max_upload_bytes: int = Field(ge=1024 * 1024, le=500 * 1024 * 1024)

backend/app/services/upload_settings_service.py

@@ -0,0 +1,33 @@
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models import UploadSettings
+from app.storage import DEFAULT_MAX_UPLOAD_BYTES
+
+
+async def get_upload_settings(db: AsyncSession) -> UploadSettings:
+    """Unlike SmtpSettings (where "no row yet" means "unconfigured, skip"),
+    an upload cap must always resolve to a usable value -- so this creates
+    the row with the default on first read instead of returning None."""
+    result = await db.execute(select(UploadSettings).limit(1))
+    settings_row = result.scalar_one_or_none()
+    if settings_row is None:
+        settings_row = UploadSettings(max_upload_bytes=DEFAULT_MAX_UPLOAD_BYTES)
+        db.add(settings_row)
+        await db.commit()
+        await db.refresh(settings_row)
+    return settings_row
+
+
+async def update_upload_settings(db: AsyncSession, *, max_upload_bytes: int) -> UploadSettings:
+    settings_row = await get_upload_settings(db)
+    settings_row.max_upload_bytes = max_upload_bytes
+    await db.commit()
+    await db.refresh(settings_row)
+    return settings_row
+
+
+def format_mb(num_bytes: int) -> str:
+    """Used in 413 error messages, which need to reflect the live
+    admin-configured cap rather than a hardcoded "8 MB"."""
+    return f"{num_bytes / (1024 * 1024):g} MB"

backend/app/storage.py

@@ -10,11 +10,10 @@ from PIL import Image, UnidentifiedImageError
 # production layout with zero new config.
 UPLOADS_DIR = pathlib.Path(__file__).resolve().parent.parent.parent / "uploads"
 
-MAX_IMAGE_BYTES = 8 * 1024 * 1024
-# Separate named constant (same value for now) so a later size-limit
-# redesign for generic file attachments doesn't have to touch image
-# behavior.
-MAX_FILE_BYTES = MAX_IMAGE_BYTES
+# Seed value for the admin-configurable UploadSettings row (see
+# app/services/upload_settings_service.py) -- also the fallback `read_capped`
+# default for call sites that don't look up the live setting.
+DEFAULT_MAX_UPLOAD_BYTES = 8 * 1024 * 1024
 _READ_CHUNK_BYTES = 1024 * 1024
 _MAX_DIMENSION = 2000
 
@@ -35,7 +34,7 @@ class InvalidImageError(Exception):
     pass
 
 
-async def read_capped(file, cap: int = MAX_IMAGE_BYTES) -> bytes:
+async def read_capped(file, cap: int = DEFAULT_MAX_UPLOAD_BYTES) -> bytes:
     """Reads an UploadFile-like object in chunks, raising as soon as `cap`
     is exceeded rather than after buffering the whole (potentially huge)
     body first."""

backend/tests/test_upload_settings.py

@@ -0,0 +1,113 @@
+import uuid
+
+from sqlalchemy import select
+
+from app.models import UploadSettings, User
+from tests.conftest import register_and_login
+
+
+async def _get_settings_row(db_session) -> UploadSettings:
+    result = await db_session.execute(select(UploadSettings))
+    return result.scalar_one()
+
+
+async def _make_admin(db_session, user_id: str) -> None:
+    user = await db_session.get(User, uuid.UUID(user_id))
+    user.is_site_admin = True
+    await db_session.commit()
+
+
+async def test_upload_settings_require_admin(client, db_session):
+    await register_and_login(client, db_session, username="alice")
+    resp = await client.get("/api/admin/settings/uploads")
+    assert resp.status_code == 403
+
+    resp = await client.put("/api/admin/settings/uploads", json={"max_upload_bytes": 1024 * 1024})
+    assert resp.status_code == 403
+
+
+async def test_upload_settings_get_defaults_to_8mb(client, db_session):
+    admin = await register_and_login(client, db_session, username="admin1")
+    await _make_admin(db_session, admin["id"])
+
+    resp = await client.get("/api/admin/settings/uploads")
+    assert resp.status_code == 200
+    assert resp.json()["max_upload_bytes"] == 8 * 1024 * 1024
+
+
+async def test_upload_settings_update(client, db_session):
+    admin = await register_and_login(client, db_session, username="admin1")
+    await _make_admin(db_session, admin["id"])
+
+    resp = await client.put("/api/admin/settings/uploads", json={"max_upload_bytes": 20 * 1024 * 1024})
+    assert resp.status_code == 200
+    assert resp.json()["max_upload_bytes"] == 20 * 1024 * 1024
+
+    resp = await client.get("/api/admin/settings/uploads")
+    assert resp.json()["max_upload_bytes"] == 20 * 1024 * 1024
+
+    row = await _get_settings_row(db_session)
+    assert row.max_upload_bytes == 20 * 1024 * 1024
+
+
+async def test_upload_settings_rejects_out_of_range(client, db_session):
+    admin = await register_and_login(client, db_session, username="admin1")
+    await _make_admin(db_session, admin["id"])
+
+    resp = await client.put("/api/admin/settings/uploads", json={"max_upload_bytes": 0})
+    assert resp.status_code == 422
+
+    resp = await client.put(
+        "/api/admin/settings/uploads", json={"max_upload_bytes": 1000 * 1024 * 1024}
+    )
+    assert resp.status_code == 422
+
+
+async def test_upload_limit_endpoint_accessible_to_any_authenticated_user(client, db_session):
+    admin = await register_and_login(client, db_session, username="admin1")
+    await _make_admin(db_session, admin["id"])
+    await client.put("/api/admin/settings/uploads", json={"max_upload_bytes": 5 * 1024 * 1024})
+
+    await register_and_login(client, db_session, username="regular")
+    resp = await client.get("/api/uploads/limit")
+    assert resp.status_code == 200
+    assert resp.json()["max_upload_bytes"] == 5 * 1024 * 1024
+
+
+async def test_lowering_limit_enforced_on_file_upload(client, db_session):
+    admin = await register_and_login(client, db_session, username="admin1")
+    await _make_admin(db_session, admin["id"])
+    await client.put("/api/admin/settings/uploads", json={"max_upload_bytes": 1024 * 1024})
+
+    room = (await client.post("/api/rooms", json={"name": "general"})).json()
+
+    resp = await client.post(
+        f"/api/rooms/{room['id']}/files",
+        files={"file": ("big.bin", b"0" * (2 * 1024 * 1024), "application/octet-stream")},
+    )
+    assert resp.status_code == 413
+    assert "1 MB" in resp.json()["detail"]
+
+    resp = await client.post(
+        f"/api/rooms/{room['id']}/files",
+        files={"file": ("small.bin", b"0" * (512 * 1024), "application/octet-stream")},
+    )
+    assert resp.status_code == 201
+
+
+async def test_raising_limit_allows_larger_image_upload(client, db_session):
+    admin = await register_and_login(client, db_session, username="admin1")
+    await _make_admin(db_session, admin["id"])
+    await client.put("/api/admin/settings/uploads", json={"max_upload_bytes": 20 * 1024 * 1024})
+
+    room = (await client.post("/api/rooms", json={"name": "general"})).json()
+
+    # 9MB would be rejected under the old hardcoded 8MB cap.
+    oversized_for_old_cap = b"0" * (9 * 1024 * 1024)
+    resp = await client.post(
+        f"/api/rooms/{room['id']}/images",
+        files={"file": ("big.bin", oversized_for_old_cap, "image/png")},
+    )
+    # Not a valid PNG, but it must get past the size check to prove the
+    # raised limit took effect -- 400 (invalid image), not 413.
+    assert resp.status_code == 400

frontend/src/api/admin.ts

@@ -6,6 +6,7 @@ import type {
   EventSubscriptionAdmin,
   SiteInvite,
   SmtpSettings,
+  UploadSettings,
   WebhookIncomingAdmin,
 } from '../types'
 
@@ -105,3 +106,14 @@ export function updateSmtpSettings(payload: SmtpSettingsPayload): Promise<SmtpSe
 export function sendTestSmtpEmail(): Promise<void> {
   return apiFetch<void>('/api/admin/settings/smtp/test', { method: 'POST' })
 }
+
+export function getUploadSettings(): Promise<UploadSettings> {
+  return apiFetch<UploadSettings>('/api/admin/settings/uploads')
+}
+
+export function updateUploadSettings(maxUploadBytes: number): Promise<UploadSettings> {
+  return apiFetch<UploadSettings>('/api/admin/settings/uploads', {
+    method: 'PUT',
+    body: JSON.stringify({ max_upload_bytes: maxUploadBytes }),
+  })
+}

frontend/src/api/uploads.ts

@@ -0,0 +1,6 @@
+import { apiFetch } from './client'
+import type { UploadSettings } from '../types'
+
+export function getUploadLimit(): Promise<UploadSettings> {
+  return apiFetch<UploadSettings>('/api/uploads/limit')
+}

frontend/src/components/Composer.tsx

@@ -1,6 +1,7 @@
-import { useRef, useState, type ChangeEvent, type KeyboardEvent } from 'react'
+import { useEffect, useRef, useState, type ChangeEvent, type KeyboardEvent } from 'react'
 import { useOnlineStatus } from '../hooks/useOnlineStatus'
 import { uploadRoomFile, uploadRoomImage } from '../api/rooms'
+import { getUploadLimit } from '../api/uploads'
 import { EmojiPicker } from './EmojiPicker'
 import './Composer.css'
 
@@ -26,10 +27,20 @@ export function Composer({ roomId, roomName, disabled, onSend }: ComposerProps)
   const [uploading, setUploading] = useState(false)
   const [uploadError, setUploadError] = useState<string | null>(null)
   const [emojiPickerOpen, setEmojiPickerOpen] = useState(false)
+  const [maxUploadBytes, setMaxUploadBytes] = useState<number | null>(null)
   const textareaRef = useRef<HTMLTextAreaElement>(null)
   const fileInputRef = useRef<HTMLInputElement>(null)
   const online = useOnlineStatus()
 
+  useEffect(() => {
+    getUploadLimit()
+      .then((limit) => setMaxUploadBytes(limit.max_upload_bytes))
+      .catch(() => {
+        // Non-critical -- if this fails, oversized uploads just get caught
+        // by the server's 413 instead of client-side, no functional loss.
+      })
+  }, [])
+
   function autoGrow() {
     const el = textareaRef.current
     if (!el) return
@@ -60,6 +71,12 @@ export function Composer({ roomId, roomName, disabled, onSend }: ComposerProps)
     if (!file) return
 
     setUploadError(null)
+
+    if (maxUploadBytes !== null && file.size > maxUploadBytes) {
+      setUploadError(`File exceeds ${formatFileSize(maxUploadBytes)} limit`)
+      return
+    }
+
     setUploading(true)
     try {
       if (file.type.startsWith('image/')) {

frontend/src/pages/AdminPage.css

@@ -338,3 +338,9 @@
   color: var(--ds-muted);
   margin: 0;
 }
+
+.admin-settings-hint {
+  font-size: 0.82rem;
+  color: var(--ds-muted);
+  margin: -4px 0 0;
+}

frontend/src/pages/AdminPage.tsx

@@ -5,6 +5,7 @@ import {
   deactivateUser,
   demoteUser,
   getSmtpSettings,
+  getUploadSettings,
   inviteUser,
   listAdminRooms,
   listAdminUsers,
@@ -20,6 +21,7 @@ import {
   transferOwnershipAdmin,
   unarchiveRoom,
   updateSmtpSettings,
+  updateUploadSettings,
 } from '../api/admin'
 import { ApiError } from '../api/client'
 import { createApiToken, createBot, listApiTokens, listBots, revokeApiToken } from '../api/bots'
@@ -37,6 +39,7 @@ import type {
   EventSubscriptionAdmin,
   SiteInvite,
   SmtpSettings,
+  UploadSettings,
   WebhookIncomingAdmin,
 } from '../types'
 import { TopBar } from '../components/TopBar'
@@ -84,6 +87,11 @@ export function AdminPage() {
   const [smtpTestBusy, setSmtpTestBusy] = useState(false)
   const [smtpTestResult, setSmtpTestResult] = useState<string | null>(null)
 
+  const [uploadSettings, setUploadSettings] = useState<UploadSettings | null>(null)
+  const [uploadLoaded, setUploadLoaded] = useState(false)
+  const [uploadMaxMb, setUploadMaxMb] = useState('8')
+  const [uploadSaving, setUploadSaving] = useState(false)
+
   function reportError(err: unknown) {
     setError(err instanceof ApiError ? err.message : String(err))
   }
@@ -134,6 +142,16 @@ export function AdminPage() {
       .catch(reportError)
   }
 
+  function loadUploadSettings() {
+    getUploadSettings()
+      .then((cfg) => {
+        setUploadSettings(cfg)
+        setUploadLoaded(true)
+        setUploadMaxMb(String(cfg.max_upload_bytes / (1024 * 1024)))
+      })
+      .catch(reportError)
+  }
+
   useEffect(() => {
     if (tab === 'users') {
       loadUsers()
@@ -148,7 +166,10 @@ export function AdminPage() {
       loadWebhooksAdmin()
     }
     if (tab === 'audit') loadAuditLog()
-    if (tab === 'settings') loadSmtpSettings()
+    if (tab === 'settings') {
+      loadSmtpSettings()
+      loadUploadSettings()
+    }
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [tab])
 
@@ -316,6 +337,21 @@ export function AdminPage() {
     }
   }
 
+  async function handleSaveUploadSettings(e: FormEvent) {
+    e.preventDefault()
+    setUploadSaving(true)
+    setError(null)
+    try {
+      const updated = await updateUploadSettings(Math.round(Number(uploadMaxMb) * 1024 * 1024))
+      setUploadSettings(updated)
+      setUploadMaxMb(String(updated.max_upload_bytes / (1024 * 1024)))
+    } catch (err) {
+      reportError(err)
+    } finally {
+      setUploadSaving(false)
+    }
+  }
+
   return (
     <div className="admin-page">
       <TopBar />
@@ -775,6 +811,34 @@ export function AdminPage() {
                 {smtpTestResult && <p className="admin-settings-test-result">{smtpTestResult}</p>}
               </form>
             )}
+
+            <h2 className="admin-subheading">Uploads</h2>
+            {!uploadLoaded && <p className="admin-placeholder">Loading…</p>}
+            {uploadLoaded && (
+              <form className="admin-settings-form" onSubmit={handleSaveUploadSettings}>
+                <label className="admin-settings-field admin-settings-field-narrow">
+                  Max attachment size (MB)
+                  <input
+                    type="number"
+                    value={uploadMaxMb}
+                    onChange={(e) => setUploadMaxMb(e.target.value)}
+                    min={1}
+                    max={500}
+                    step={1}
+                    required
+                  />
+                </label>
+                <p className="admin-settings-hint">
+                  Applies to message images, message file attachments, and avatars. Current limit:{' '}
+                  {uploadSettings ? `${uploadSettings.max_upload_bytes / (1024 * 1024)} MB` : '—'}.
+                </p>
+                <div className="admin-settings-actions">
+                  <button type="submit" className="btn-primary" disabled={uploadSaving}>
+                    {uploadSaving ? 'Saving…' : 'Save'}
+                  </button>
+                </div>
+              </form>
+            )}
           </>
         )}
       </div>

frontend/src/types.ts

@@ -225,3 +225,8 @@ export interface SmtpSettings {
   use_tls: boolean
   updated_at: string
 }
+
+export interface UploadSettings {
+  max_upload_bytes: number
+  updated_at: string
+}