feat(upload): add resumable chunk configuration and file validation

- Add `WARPBOX_RESUMABLE_CHUNK_MODE` and `WARPBOX_RESUMABLE_CHUNK_PATH` environment variables to configure temporary chunk storage.
- Implement strict file validation for resuming uploads to ensure selected files match the pending session's metadata.
- Add `PLANS.md` to document development stages, roadmap, and API specifications (including batching and resumable flows).

.env.example

@@ -9,6 +9,11 @@ WARPBOX_CLEANUP_ENABLED=true
 WARPBOX_CLEANUP_EVERY=1h
 WARPBOX_THUMBNAIL_ENABLED=true
 WARPBOX_THUMBNAIL_EVERY=1m
+WARPBOX_RESUMABLE_UPLOADS_ENABLED=true
+WARPBOX_RESUMABLE_CHUNK_MB=64
+WARPBOX_RESUMABLE_RETENTION_HOURS=1
+WARPBOX_RESUMABLE_CHUNK_MODE=same
+WARPBOX_RESUMABLE_CHUNK_PATH=
 WARPBOX_MAX_UPLOAD_SIZE_MB=16384
 WARPBOX_ANONYMOUS_UPLOADS_ENABLED=true
 WARPBOX_ANONYMOUS_MAX_UPLOAD_MB=512

PLANS.md

@@ -0,0 +1,111 @@
+# Warpbox Plans & Staged Development
+
+This document captures the staged development history and roadmap for Warpbox. For day-to-day usage,
+configuration, and deployment, see [README.md](./README.md).
+
+## Stage 2 — Operator Tools
+
+- `/admin/login` - token-based admin login.
+- `/admin` - overview metrics: boxes, files, storage, recent uploads, protected/expired boxes.
+- `/admin/files` - recent upload table with view and delete actions.
+- Expired boxes and boxes that have reached their download limit are cleaned on startup and then
+  every `WARPBOX_CLEANUP_EVERY` when `WARPBOX_CLEANUP_ENABLED=true`.
+- Missing image/video thumbnails are generated in a background worker every `WARPBOX_THUMBNAIL_EVERY`
+  when `WARPBOX_THUMBNAIL_ENABLED=true`.
+
+## Stage 3 — Anonymous Integrations
+
+Anonymous uploads return a private management link at creation time. Keep that link secret: anyone
+with it can delete the entire upload box. The raw delete token is not stored and cannot be recovered
+later.
+
+Browser uploads still show `Open box` and `Copy URL` as the primary actions, with a smaller
+`Manage or delete this upload` link in the completion panel.
+
+Curl and custom uploaders can use the same endpoint:
+
+```bash
+# Terminal-friendly output: one plain box URL.
+curl -F file=@./report.pdf http://localhost:8080/api/v1/upload
+
+# JSON output with boxUrl, thumbnailUrl, manageUrl, deleteUrl, zipUrl, and file entries.
+curl -F sharex=@./screenshot.png \
+  -H 'Accept: application/json' \
+  http://localhost:8080/api/v1/upload
+```
+
+The upload endpoint accepts multipart fields named `file` and `sharex`. ShareX users can start from
+`examples/sharex/warpbox-anonymous.sxcu`; update `RequestURL` to match your instance URL.
+Authenticated uploads (your account's limits) add an `Authorization: Bearer <token>` header — mint a
+token under **Account → Access tokens**. The JSON response uses ShareX placeholders `{json:boxUrl}`
+(URL), `{json:thumbnailUrl}` (thumbnail), `{json:deleteUrl}` (deletion), and `{json:error}` (error
+message).
+
+### Grouping multiple files into one box (`X-Warpbox-Batch`)
+
+By default every uploaded file becomes its own box. To put several files in a **single** box, send
+the opt-in `X-Warpbox-Batch` header: requests that share the same header value (scoped per account,
+or per IP for anonymous uploads) within 20s are appended to the same box. This lets a multi-file
+ShareX selection — which ShareX sends as separate back-to-back requests — land as one shareable link.
+The shipped `.sxcu` sets `X-Warpbox-Batch: sharex`; remove that header for one box per file. Requests
+without the header behave exactly as before.
+
+### Resumable API flow
+
+Custom clients can use the resumable JSON API for large files:
+
+```bash
+# 1. Create a resumable session from file metadata.
+curl -s http://localhost:8080/api/v1/uploads/resumable \
+  -H 'Accept: application/json' \
+  -H 'Content-Type: application/json' \
+  -d '{"files":[{"name":"large.bin","size":1048576,"contentType":"application/octet-stream"}],"expiresMinutes":1440}'
+
+# 2. Upload exact-sized chunks using the returned sessionId, file id, and chunkSize.
+dd if=./large.bin bs=8388608 count=1 skip=0 2>/dev/null | \
+  curl -X PUT --data-binary @- \
+  http://localhost:8080/api/v1/uploads/resumable/SESSION_ID/files/FILE_ID/chunks/0
+
+# 3. Complete the session after all chunks are present.
+curl -X POST -H 'Accept: application/json' \
+  http://localhost:8080/api/v1/uploads/resumable/SESSION_ID/complete
+```
+
+The complete response is the same JSON shape as `POST /api/v1/upload`, including `boxUrl`,
+`manageUrl`, `deleteUrl`, and file URLs. Send `Authorization: Bearer <token>` on every resumable
+request to upload as an account.
+
+Browser resumable uploads are configurable from `/admin/settings`: enabled/disabled, chunk size in
+MB, draft retention hours, and chunk staging location. The default chunk mode stores temporary draft
+chunks under `data/tmp/uploads/{session_id}`. A custom mode can point those chunks at another local
+path, such as a mounted fast SSD. Chunk staging stays local even when the completed files are later
+finalized into S3/SFTP/SMB/WebDAV storage. Completion returns the share link immediately; files may
+show as `Processing` on the download page while the background finalizer streams them to the selected
+storage backend. Cleanup removes expired uploading drafts but skips sessions already in processing.
+
+## Stage 4 — Accounts + Personal Boxes
+
+- `/register` bootstraps the first admin account only when no users exist.
+- `/login` and `/logout` provide cookie-based web sessions.
+- `/app` is the personal dashboard for logged-in users, showing owned boxes, storage usage, upload
+  history, and flat collections. Uploading still happens from the homepage.
+- `/admin/users` lets admins create invite links, disable/reactivate users, and generate reset links.
+- Logged-in browser uploads from `/` still use `POST /api/v1/upload`, but the resulting box is stored
+  with owner and optional collection metadata.
+- Admin users are exempt from the global max upload size on the homepage upload flow. Future per-user
+  quotas should apply to this same upload path rather than creating a second uploader.
+- `/admin/settings` controls anonymous uploads, anonymous max upload size, daily upload caps, default
+  user storage quota, and usage retention.
+- `/admin/users` shows storage/daily usage and lets admins set per-user storage quota overrides.
+- `/admin/storage` manages the built-in local file backend and S3-compatible bucket backends.
+- `/admin/bans` manages manual IP/CIDR bans and optional automatic bans for suspicious probes and
+  repeated login failures. Auto-ban is off by default and configured from the admin UI.
+- Upload limits now include daily bytes, daily box counts, active box counts, short-window request
+  limits, max expiration days, local storage capacity in GB, and per-user policy overrides.
+- Uploaded file content, thumbnails, and private box metadata use the selected storage backend. The
+  bbolt database and JSON logs remain local under `./data/db` and `./data/logs`.
+- Anonymous uploads, ShareX uploads, unlisted public box links, password protection, expiry, delete
+  tokens, thumbnails, and cleanup continue to work as before.
+
+Email delivery is intentionally deferred. Invite and reset links are copyable today; future SMTP
+support will power public forgot-password and optional email delivery.

README.md

@@ -1,6 +1,20 @@
 # Warpbox.dev
 
-This repository contains the Go backend base for `warpbox.dev`, a self-hosted transfer-first file sharing application.
+Warpbox is a self-hosted, transfer first file sharing application written in Go. It renders
+server side templates and serves static assets directly.
+
+## Features
+
+- Anonymous and authenticated uploads from the browser, `curl`, or ShareX.
+- Warpbox-native resumable uploads with a JSON API for large files.
+- Upload boxes with expiry, optional download limits, password protection, and one time delete tokens.
+- User accounts with personal dashboards, collections, storage quotas, and invite based registration.
+- Admin tooling for metrics, file management, storage backends, upload policy, and IP bans.
+- Local and S3 compatible storage backends.
+- Background jobs for cleanup and thumbnail generation.
+- Emoji reaction packs loaded from the runtime data directory.
+
+> Looking for the roadmap and the staged development history? See [PLANS.md](./PLANS.md).
 
 ## Run
 
@@ -10,11 +24,25 @@ This repository contains the Go backend base for `warpbox.dev`, a self-hosted tr
 
 The default server listens on `:8080`.
 
-Upload size limits are configured in megabytes through `WARPBOX_MAX_UPLOAD_SIZE_MB`.
-Fractions are supported, so `0.5Mb` is 512 KiB and `1.5Mb` is 1536 KiB.
+For one off Go commands, run them from the backend module:
 
-Upload policy defaults are also configured in megabytes and can later be changed from
-`/admin/settings`:
+```bash
+cd backend
+go run ./cmd/warpbox
+```
+
+## Configuration
+
+All configuration comes from environment variables. The dev script sources `scripts/env/dev.env`.
+
+### Upload size
+
+Upload size limits are configured in megabytes through `WARPBOX_MAX_UPLOAD_SIZE_MB`. Fractions are
+supported, so `0.5Mb` is 512 KiB and `1.5Mb` is 1536 KiB.
+
+### Upload policy defaults
+
+These defaults can later be changed from `/admin/settings`:
 
 - `WARPBOX_ANONYMOUS_UPLOADS_ENABLED=true`
 - `WARPBOX_ANONYMOUS_MAX_UPLOAD_MB=512`
@@ -33,32 +61,150 @@ Upload policy defaults are also configured in megabytes and can later be changed
 - `WARPBOX_SHORT_WINDOW_SECONDS=60`
 - `WARPBOX_ANONYMOUS_STORAGE_BACKEND=local`
 - `WARPBOX_USER_STORAGE_BACKEND=local`
-- `WARPBOX_TRUSTED_PROXIES=` controls whether forwarded client IP headers are accepted only from specific proxy IPs/CIDRs. See [SECURITY_PROXY.md](./SECURITY_PROXY.md).
+- `WARPBOX_RESUMABLE_UPLOADS_ENABLED=true`
+- `WARPBOX_RESUMABLE_CHUNK_MB=8`
+- `WARPBOX_RESUMABLE_RETENTION_HOURS=24`
+- `WARPBOX_RESUMABLE_CHUNK_MODE=same`
+- `WARPBOX_RESUMABLE_CHUNK_PATH=`
+- `WARPBOX_TRUSTED_PROXIES=` controls whether forwarded client IP headers are accepted only from
+ specific proxy IPs/CIDRs. See [SECURITY_PROXY.md](./SECURITY_PROXY.md).
+
+Resumable settings are seeded from the environment and can then be edited from `/admin/settings`.
+Saved admin settings override these env defaults. `WARPBOX_RESUMABLE_CHUNK_MODE=same` stores draft
+chunks in the normal local temp path, `data/tmp/uploads/{session_id}` under `WARPBOX_DATA_DIR`.
+`WARPBOX_RESUMABLE_CHUNK_MODE=custom` uses `WARPBOX_RESUMABLE_CHUNK_PATH` instead, for example a
+mounted fast SSD path. Chunk storage is always local temporary staging; completed files are finalized
+into the selected storage backend after all chunks arrive.
+
+### Timeouts
+
+Large uploads are expected to take minutes on normal home/server connections. Keep
+`WARPBOX_READ_TIMEOUT=0s` and `WARPBOX_WRITE_TIMEOUT=0s` so Go does not close the connection
+mid upload; `WARPBOX_READ_HEADER_TIMEOUT=15s` still protects header reads from slowloris style
+connections.
+
+### Data directory
 
 Runtime data is configured with `WARPBOX_DATA_DIR` and defaults to `./data` in the dev environment.
 The dev script resolves that path from the repository root.
 
-Large uploads are expected to take minutes on normal home/server connections. Keep
-`WARPBOX_READ_TIMEOUT=0s` and `WARPBOX_WRITE_TIMEOUT=0s` so Go does not close the connection
-mid-upload; `WARPBOX_READ_HEADER_TIMEOUT=15s` still protects header reads from slowloris-style
-connections.
+### Background jobs
 
 Background jobs are enabled with `WARPBOX_JOBS_ENABLED=true`. Individual jobs can be toggled with
 `WARPBOX_CLEANUP_ENABLED` and `WARPBOX_THUMBNAIL_ENABLED`, and their schedules are configured with
 `WARPBOX_CLEANUP_EVERY` and `WARPBOX_THUMBNAIL_EVERY`.
 
+- **Cleanup**: expired boxes and boxes that have reached their download limit are cleaned on startup
+ and then on schedule. Stale resumable sessions are removed after `WARPBOX_RESUMABLE_RETENTION_HOURS`.
+- **Thumbnails**: missing image/video thumbnails are generated in a background worker.
+
+## First run bootstrap
+
 On a fresh data directory, visit `/register` to create the first account. That first user becomes
 the instance admin and normal registration closes after bootstrap. Admins can create copyable invite
 links from `/admin/users`.
 
-The env admin token still exists as emergency fallback access. Set `WARPBOX_ADMIN_TOKEN` and use it
-at `/admin/login` if you need to recover access without a user session.
+The env admin token exists as emergency fallback access. Set `WARPBOX_ADMIN_TOKEN` and use it at
+`/admin/login` if you need to recover access without a user session.
+
+## Uploads
+
+Browser uploads use Warpbox native resumable uploads by default. Resumable behavior is configurable
+from `/admin/settings`, including enable/disable, chunk size, retention, and whether chunks use the
+default local temp path or a custom local path such as a fast SSD. When all chunks arrive, Warpbox
+returns the share link immediately and marks files as `Processing` until the background finalizer
+streams them into the selected storage backend. Draft chunks are deleted once finalization succeeds.
+Expired uploading drafts are cleaned after the configured retention window; sessions already in
+`Processing` are protected from cleanup while finalization is running.
+
+### Anonymous uploads
+
+Anonymous uploads return a private management link at creation time. Keep that link secret: anyone
+with it can delete the entire upload box. The raw delete token is not stored and cannot be recovered
+later. Browser uploads show `Open box` and `Copy URL` as the primary actions, with a smaller
+`Manage or delete this upload` link in the completion panel.
+
+### `curl` and ShareX
+
+```bash
+# Terminal-friendly output: one plain box URL.
+curl -F file=@./report.pdf http://localhost:8080/api/v1/upload
+
+# JSON output with boxUrl, thumbnailUrl, manageUrl, deleteUrl, zipUrl, and file entries.
+curl -F sharex=@./screenshot.png \
+ -H 'Accept: application/json' \
+ http://localhost:8080/api/v1/upload
+```
+
+The upload endpoint accepts multipart fields named `file` and `sharex`. ShareX users can start from
+`examples/sharex/warpbox-anonymous.sxcu`; update `RequestURL` to match your instance URL.
+Authenticated uploads (your account's limits) add an `Authorization: Bearer <token>` header mint a
+token under **Account → Access tokens**. The JSON response uses ShareX placeholders `{json:boxUrl}`
+(URL), `{json:thumbnailUrl}` (thumbnail), `{json:deleteUrl}` (deletion), and `{json:error}` (error
+message).
+
+### Grouping multiple files into one box (`X-Warpbox-Batch`)
+
+By default every uploaded file becomes its own box. To put several files in a **single** box, send
+the opt-in `X-Warpbox-Batch` header: requests that share the same header value (scoped per account,
+or per IP for anonymous uploads) within 20s are appended to the same box. This lets a multi-file
+ShareX selection which ShareX sends as separate back-to-back requests land as one shareable link.
+The shipped `.sxcu` sets `X-Warpbox-Batch: sharex`; remove that header for one box per file. Requests
+without the header behave exactly as before.
+
+### Resumable API flow
+
+Custom clients can use the resumable JSON API for large files:
+
+```bash
+# 1. Create a resumable session from file metadata.
+curl -s http://localhost:8080/api/v1/uploads/resumable \
+ -H 'Accept: application/json' \
+ -H 'Content-Type: application/json' \
+ -d '{"files":[{"name":"large.bin","size":1048576,"contentType":"application/octet-stream"}],"expiresMinutes":1440}'
+
+# 2. Upload exact-sized chunks using the returned sessionId, file id, and chunkSize.
+dd if=./large.bin bs=8388608 count=1 skip=0 2>/dev/null | \
+ curl -X PUT --data-binary @- \
+ http://localhost:8080/api/v1/uploads/resumable/SESSION_ID/files/FILE_ID/chunks/0
+
+# 3. Complete the session after all chunks are present.
+curl -X POST -H 'Accept: application/json' \
+ http://localhost:8080/api/v1/uploads/resumable/SESSION_ID/complete
+```
+
+The complete response is the same JSON shape as `POST /api/v1/upload`, including `boxUrl`,
+`manageUrl`, `deleteUrl`, and file URLs. Send `Authorization: Bearer <token>` on every resumable
+request to upload as an account.
+
+## Accounts and admin
+
+- `/register` bootstraps the first admin account only when no users exist.
+- `/login` and `/logout` provide cookie-based web sessions.
+- `/app` is the personal dashboard for logged-in users, showing owned boxes, storage usage, upload
+ history, and flat collections. Uploading still happens from the homepage.
+- `/admin` shows overview metrics: boxes, files, storage, recent uploads, protected/expired boxes.
+- `/admin/files` is a recent upload table with view and delete actions.
+- `/admin/users` lets admins create invite links, disable/reactivate users, generate reset links,
+ view storage/daily usage, and set per-user storage quota overrides.
+- `/admin/settings` controls anonymous uploads, anonymous max upload size, daily upload caps, default
+ user storage quota, and usage retention.
+- `/admin/storage` manages the built-in local file backend and S3-compatible bucket backends.
+- `/admin/bans` manages manual IP/CIDR bans and optional automatic bans for suspicious probes and
+ repeated login failures. Auto-ban is off by default and configured from the admin UI.
+
+Logged-in browser uploads from `/` use `POST /api/v1/upload`, and the resulting box is stored with
+owner and optional collection metadata. Admin users are exempt from the global max upload size on the
+homepage upload flow.
+
+Email delivery is intentionally deferred. Invite and reset links are copyable today; future SMTP
+support will power public forgot-password and optional email delivery.
 
 ## Emoji reaction packs
 
 File reactions use emoji packs from the runtime data directory, not from the application code. By
-default that means `./data/emoji`; if you change `WARPBOX_DATA_DIR`, use
-`$WARPBOX_DATA_DIR/emoji` instead.
+default that means `./data/emoji`; if you change `WARPBOX_DATA_DIR`, use `$WARPBOX_DATA_DIR/emoji`
+instead.
 
 Each folder under `./data/emoji` becomes one emoji tab in the reaction picker. Put image files
 directly inside the pack folder:
@@ -69,35 +215,30 @@ data/
 ├── files/
 ├── logs/
 └── emoji/
-    ├── openmoji/
-    │   ├── 1F600.svg
-    │   ├── 1F44D.svg
-    │   └── 2764.svg
-    ├── pixel-pack/
-    │   ├── happy.webp
-    │   ├── fire.webp
-    │   └── star.webp
-    └── custom-work/
-        ├── approved.png
-        └── shipped.png
+  ├── openmoji/
+  │  ├── 1F600.svg
+  │  ├── 1F44D.svg
+  │  └── 2764.svg
+  ├── pixel-pack/
+  │  ├── happy.webp
+  │  ├── fire.webp
+  │  └── star.webp
+  └── custom-work/
+    ├── approved.png
+    └── shipped.png
 ```
 
-In this example, the picker shows tabs named `Openmoji`, `Pixel pack`, and `Custom work`.
-Supported emoji image extensions are `.svg`, `.webp`, `.png`, `.jpg`, `.jpeg`, and `.gif`.
+In this example, the picker shows tabs named `Openmoji`, `Pixel pack`, and `Custom work`. Supported
+emoji image extensions are `.svg`, `.webp`, `.png`, `.jpg`, `.jpeg`, and `.gif`.
 
-For one-off Go commands, run them from the backend module:
+## Deployment
 
-```bash
-cd backend
-go run ./cmd/warpbox
-```
-
-## Docker / Podman
+### Docker / Podman
 
 Copy the example environment file and adjust values such as `WARPBOX_BASE_URL` and
-`WARPBOX_ADMIN_TOKEN` before running the container:
-
-Copy the example [docker-compose.example.yml](./docker-compose.example.yml) to [docker-compose.yml](./docker-compose.yml), modify as need-be
+`WARPBOX_ADMIN_TOKEN` before running the container. Copy the example
+[docker-compose.example.yml](./docker-compose.example.yml) to
+[docker-compose.yml](./docker-compose.yml), modify as need-be:
 
 ```bash
 cp .env.example .env
@@ -105,20 +246,19 @@ docker compose -f docker-compose.yml up --build
 ```
 
 The compose example also works with Podman compatible compose tools. Its data volume uses
-`./data:/data:Z` for SELinux relabeling, and the container overrides runtime paths to use
-`/data`, `/app/static`, and `/app/templates`.
+`./data:/data:Z` for SELinux relabeling, and the container overrides runtime paths to use `/data`,
+`/app/static`, and `/app/templates`. The image exposes the health endpoint `/health`, which Docker
+and compose healthchecks use.
 
-The image exposes the health endpoint: `/health`. Docker and compose healthchecks use it.
-
-## Reverse Proxy Security
+### Reverse proxy security
 
 Warpbox uses the resolved client IP for anonymous limits, manual bans, and automatic bans. The
 default behavior trusts `X-Forwarded-For` and `X-Real-IP` so a normal Caddy reverse proxy works
-without extra setup. For hardened deployments where the app port might be reachable from more than
-one network, set `WARPBOX_TRUSTED_PROXIES` to trusted proxy IPs/CIDRs. See
+without extra setup. For hardened deployments where the app port might be reachable from more than one
+network, set `WARPBOX_TRUSTED_PROXIES` to trusted proxy IPs/CIDRs. See
 [SECURITY_PROXY.md](./SECURITY_PROXY.md) for Caddy examples and Docker/systemd notes.
 
-## Systemd
+### Systemd
 
 Build the binary on the server, create a dedicated user, and keep runtime data outside the repo:
 
@@ -180,7 +320,23 @@ sudo systemctl status warpbox
 
 Put Caddy in front of `127.0.0.1:6070` and keep the Warpbox port closed to the public internet.
 
-## Layout
+## Runtime data
+
+Warpbox keeps local runtime data under the configured data directory:
+
+- `data/files/{box_id}/@each@{file_id}.ext` - uploaded file contents when the local backend is selected.
+- `data/files/{box_id}/@thumb@{file_id}.jpg` - generated previews when the local backend is selected.
+- `data/tmp/uploads/{session_id}` - temporary local chunks for unfinished resumable uploads when
+ the default chunk mode is selected.
+- `data/db/warpbox.bbolt` - bbolt metadata database for boxes, file records, users, sessions,
+ invites, collections, upload policy settings, daily usage records, manual bans, automatic ban
+ settings, abuse counters, and malicious path rules.
+- `data/logs/{YYYY-MM-DD}.log` - JSONL logs, one event per line.
+
+Uploaded file content, thumbnails, and private box metadata use the selected storage backend. The
+bbolt database and JSON logs always remain local under `./data/db` and `./data/logs`.
+
+## Project layout
 
 - `backend/cmd/warpbox` - main application entry point.
 - `backend/libs/config` - environment-backed configuration.
@@ -188,7 +344,7 @@ Put Caddy in front of `127.0.0.1:6070` and keep the Warpbox port closed to the p
 - `backend/libs/handlers` - HTTP handlers for pages, API, health, static files.
 - `backend/libs/jobs` - background job registration and job loop definitions.
 - `backend/libs/middleware` - request logging, recovery, security headers, gzip, request IDs.
-- `backend/libs/services` - business logic boundaries, starting with upload limits.
+- `backend/libs/services` - business logic boundaries.
 - `backend/libs/helpers` - small reusable helpers.
 - `backend/libs/web` - Go template renderer.
 - `backend/templates` - server-rendered Go templates.
@@ -197,92 +353,7 @@ Put Caddy in front of `127.0.0.1:6070` and keep the Warpbox port closed to the p
 - `scripts/env/dev.env.example` - tracked development environment template.
 - `scripts/env/dev.env` - local development environment, ignored by git.
 
-## Stage 2 Operator Tools
+## Static asset policy
 
-- `/admin/login` - token-based admin login.
-- `/admin` - overview metrics: boxes, files, storage, recent uploads, protected/expired boxes.
-- `/admin/files` - recent upload table with view and delete actions.
-- Expired boxes and boxes that have reached their download limit are cleaned on startup and then every `WARPBOX_CLEANUP_EVERY` when `WARPBOX_CLEANUP_ENABLED=true`.
-- Missing image/video thumbnails are generated in a background worker every `WARPBOX_THUMBNAIL_EVERY` when `WARPBOX_THUMBNAIL_ENABLED=true`.
-
-## Stage 3 Anonymous Integrations
-
-Anonymous uploads now return a private management link at creation time. Keep that link secret:
-anyone with it can delete the entire upload box. The raw delete token is not stored and cannot be
-recovered later.
-
-Browser uploads still show `Open box` and `Copy URL` as the primary actions, with a smaller
-`Manage or delete this upload` link in the completion panel.
-
-Curl and custom uploaders can use the same endpoint:
-
-```bash
-# Terminal-friendly output: one plain box URL.
-curl -F file=@./report.pdf http://localhost:8080/api/v1/upload
-
-# JSON output with boxUrl, thumbnailUrl, manageUrl, deleteUrl, zipUrl, and file entries.
-curl -F sharex=@./screenshot.png \
-  -H 'Accept: application/json' \
-  http://localhost:8080/api/v1/upload
-```
-
-The upload endpoint accepts multipart fields named `file` and `sharex`. ShareX users can start
-from `examples/sharex/warpbox-anonymous.sxcu`; update `RequestURL` to match your instance URL.
-Authenticated uploads (your account's limits) add an `Authorization: Bearer <token>` header — mint
-a token under **Account → Access tokens**. The JSON response uses ShareX placeholders
-`{json:boxUrl}` (URL), `{json:thumbnailUrl}` (thumbnail), `{json:deleteUrl}` (deletion), and
-`{json:error}` (error message).
-
-### Grouping multiple files into one box (`X-Warpbox-Batch`)
-
-By default every uploaded file becomes its own box. To put several files in a **single** box, send
-the opt-in `X-Warpbox-Batch` header: requests that share the same header value (scoped per account,
-or per IP for anonymous uploads) within 20s are appended to the same box. This lets a multi-file
-ShareX selection — which ShareX sends as separate back-to-back requests — land as one shareable
-link. The shipped `.sxcu` sets `X-Warpbox-Batch: sharex`; remove that header for one box per file.
-Requests without the header behave exactly as before.
-
-## Stage 4 Accounts + Personal Boxes
-
-- `/register` bootstraps the first admin account only when no users exist.
-- `/login` and `/logout` provide cookie-based web sessions.
-- `/app` is the personal dashboard for logged-in users, showing owned boxes, storage usage, upload
-  history, and flat collections. Uploading still happens from the homepage.
-- `/admin/users` lets admins create invite links, disable/reactivate users, and generate reset links.
-- Logged-in browser uploads from `/` still use `POST /api/v1/upload`, but the resulting box is
-  stored with owner and optional collection metadata.
-- Admin users are exempt from the global max upload size on the homepage upload flow. Future
-  per-user quotas should apply to this same upload path rather than creating a second uploader.
-- `/admin/settings` controls anonymous uploads, anonymous max upload size, daily upload caps, default
-  user storage quota, and usage retention.
-- `/admin/users` shows storage/daily usage and lets admins set per-user storage quota overrides.
-- `/admin/storage` manages the built-in local file backend and S3-compatible bucket backends.
-- `/admin/bans` manages manual IP/CIDR bans and optional automatic bans for suspicious probes and
-  repeated login failures. Auto-ban is off by default and configured from the admin UI.
-- Upload limits now include daily bytes, daily box counts, active box counts, short-window request
-  limits, max expiration days, local storage capacity in GB, and per-user policy overrides.
-- Uploaded file content, thumbnails, and private box metadata use the selected storage backend.
-  The bbolt database and JSON logs remain local under `./data/db` and `./data/logs`.
-- Anonymous uploads, ShareX uploads, unlisted public box links, password protection, expiry, delete
-  tokens, thumbnails, and cleanup continue to work as before.
-
-Email delivery is intentionally deferred. Invite and reset links are copyable today; future SMTP
-support will power public forgot-password and optional email delivery.
-
-## Runtime Data
-
-Warpbox keeps local runtime data under the configured data directory:
-
-- `data/files/{box_id}/@each@{file_id}.ext` - uploaded file contents when the local backend is selected.
-- `data/files/{box_id}/@thumb@{file_id}.jpg` - generated previews when the local backend is selected.
-- `data/db/warpbox.bbolt` - bbolt metadata database for boxes and file records.
-- `data/db/warpbox.bbolt` also stores users, sessions, invites, and collections.
-- `data/db/warpbox.bbolt` stores upload policy settings and daily usage records keyed by plain IP
-  for anonymous uploads and user ID for signed-in uploads.
-- `data/db/warpbox.bbolt` stores manual bans, automatic ban settings, abuse counters, and malicious
-  path rules.
-- `data/logs/{YYYY-MM-DD}.log` - JSONL logs, one event per line.
-
-## Static Asset Policy
-
-The static handler sets long-lived immutable caching for images, video, audio, and fonts, shorter caching for CSS/JS, and gzip compression for compressible responses.
+The static handler sets long-lived immutable caching for images, video, audio, and fonts, shorter
+caching for CSS/JS, and gzip compression for compressible responses.

backend/libs/config/config.go

@@ -11,27 +11,30 @@ import (
 )
 
 type Config struct {
-	AppName           string
-	AppVersion        string
-	Environment       string
-	Addr              string
-	BaseURL           string
-	DataDir           string
-	AdminToken        string
-	StaticDir         string
-	TemplateDir       string
-	ReadHeaderTimeout time.Duration
-	ReadTimeout       time.Duration
-	WriteTimeout      time.Duration
-	IdleTimeout       time.Duration
-	TrustedProxies    []string
-	JobsEnabled       bool
-	CleanupEnabled    bool
-	CleanupEvery      time.Duration
-	ThumbnailEnabled  bool
-	ThumbnailEvery    time.Duration
-	MaxUploadSize     int64
-	DefaultSettings   SettingsDefaults
+	AppName                 string
+	AppVersion              string
+	Environment             string
+	Addr                    string
+	BaseURL                 string
+	DataDir                 string
+	AdminToken              string
+	StaticDir               string
+	TemplateDir             string
+	ReadHeaderTimeout       time.Duration
+	ReadTimeout             time.Duration
+	WriteTimeout            time.Duration
+	IdleTimeout             time.Duration
+	TrustedProxies          []string
+	JobsEnabled             bool
+	CleanupEnabled          bool
+	CleanupEvery            time.Duration
+	ThumbnailEnabled        bool
+	ThumbnailEvery          time.Duration
+	ResumableUploadsEnabled bool
+	ResumableChunkSize      int64
+	ResumableRetention      time.Duration
+	MaxUploadSize           int64
+	DefaultSettings         SettingsDefaults
 }
 
 type SettingsDefaults struct {
@@ -52,30 +55,38 @@ type SettingsDefaults struct {
 	ShortWindowSeconds      int
 	AnonymousStorageBackend string
 	UserStorageBackend      string
+	ResumableUploadsEnabled bool
+	ResumableChunkSizeMB    float64
+	ResumableRetentionHours int
+	ResumableChunkMode      string
+	ResumableChunkPath      string
 }
 
 func Load() (Config, error) {
 	cfg := Config{
-		AppName:           envString("WARPBOX_APP_NAME", "warpbox.dev"),
-		AppVersion:        envString("APP_VERSION", "dev"),
-		Environment:       envString("WARPBOX_ENV", "development"),
-		Addr:              envString("WARPBOX_ADDR", ":8080"),
-		BaseURL:           strings.TrimRight(envString("WARPBOX_BASE_URL", "http://localhost:8080"), "/"),
-		DataDir:           envString("WARPBOX_DATA_DIR", defaultPath("data")),
-		AdminToken:        envString("WARPBOX_ADMIN_TOKEN", ""),
-		StaticDir:         envString("WARPBOX_STATIC_DIR", defaultPath("static")),
-		TemplateDir:       envString("WARPBOX_TEMPLATE_DIR", defaultPath("templates")),
-		ReadHeaderTimeout: envDuration("WARPBOX_READ_HEADER_TIMEOUT", 15*time.Second),
-		ReadTimeout:       envDuration("WARPBOX_READ_TIMEOUT", 0),
-		WriteTimeout:      envDuration("WARPBOX_WRITE_TIMEOUT", 0),
-		IdleTimeout:       envDuration("WARPBOX_IDLE_TIMEOUT", 120*time.Second),
-		TrustedProxies:    envCSV("WARPBOX_TRUSTED_PROXIES"),
-		JobsEnabled:       envBool("WARPBOX_JOBS_ENABLED", true),
-		CleanupEnabled:    envBool("WARPBOX_CLEANUP_ENABLED", true),
-		CleanupEvery:      envDuration("WARPBOX_CLEANUP_EVERY", time.Hour),
-		ThumbnailEnabled:  envBool("WARPBOX_THUMBNAIL_ENABLED", true),
-		ThumbnailEvery:    envDuration("WARPBOX_THUMBNAIL_EVERY", time.Minute),
-		MaxUploadSize:     envMegabytes("WARPBOX_MAX_UPLOAD_SIZE_MB", 2048), // 2 GiB default.
+		AppName:                 envString("WARPBOX_APP_NAME", "warpbox.dev"),
+		AppVersion:              envString("APP_VERSION", "dev"),
+		Environment:             envString("WARPBOX_ENV", "development"),
+		Addr:                    envString("WARPBOX_ADDR", ":8080"),
+		BaseURL:                 strings.TrimRight(envString("WARPBOX_BASE_URL", "http://localhost:8080"), "/"),
+		DataDir:                 envString("WARPBOX_DATA_DIR", defaultPath("data")),
+		AdminToken:              envString("WARPBOX_ADMIN_TOKEN", ""),
+		StaticDir:               envString("WARPBOX_STATIC_DIR", defaultPath("static")),
+		TemplateDir:             envString("WARPBOX_TEMPLATE_DIR", defaultPath("templates")),
+		ReadHeaderTimeout:       envDuration("WARPBOX_READ_HEADER_TIMEOUT", 15*time.Second),
+		ReadTimeout:             envDuration("WARPBOX_READ_TIMEOUT", 0),
+		WriteTimeout:            envDuration("WARPBOX_WRITE_TIMEOUT", 0),
+		IdleTimeout:             envDuration("WARPBOX_IDLE_TIMEOUT", 120*time.Second),
+		TrustedProxies:          envCSV("WARPBOX_TRUSTED_PROXIES"),
+		JobsEnabled:             envBool("WARPBOX_JOBS_ENABLED", true),
+		CleanupEnabled:          envBool("WARPBOX_CLEANUP_ENABLED", true),
+		CleanupEvery:            envDuration("WARPBOX_CLEANUP_EVERY", time.Hour),
+		ThumbnailEnabled:        envBool("WARPBOX_THUMBNAIL_ENABLED", true),
+		ThumbnailEvery:          envDuration("WARPBOX_THUMBNAIL_EVERY", time.Minute),
+		ResumableUploadsEnabled: envBool("WARPBOX_RESUMABLE_UPLOADS_ENABLED", true),
+		ResumableChunkSize:      envMegabytes("WARPBOX_RESUMABLE_CHUNK_MB", 8),
+		ResumableRetention:      time.Duration(envInt("WARPBOX_RESUMABLE_RETENTION_HOURS", 24)) * time.Hour,
+		MaxUploadSize:           envMegabytes("WARPBOX_MAX_UPLOAD_SIZE_MB", 2048), // 2 GiB default.
 		DefaultSettings: SettingsDefaults{
 			AnonymousUploadsEnabled: envBool("WARPBOX_ANONYMOUS_UPLOADS_ENABLED", true),
 			AnonymousMaxUploadMB:    envMegabytesLimitFloat("WARPBOX_ANONYMOUS_MAX_UPLOAD_MB", 512),
@@ -94,8 +105,13 @@ func Load() (Config, error) {
 			ShortWindowSeconds:      envInt("WARPBOX_SHORT_WINDOW_SECONDS", 60),
 			AnonymousStorageBackend: envString("WARPBOX_ANONYMOUS_STORAGE_BACKEND", "local"),
 			UserStorageBackend:      envString("WARPBOX_USER_STORAGE_BACKEND", "local"),
+			ResumableChunkMode:      envString("WARPBOX_RESUMABLE_CHUNK_MODE", "same"),
+			ResumableChunkPath:      envString("WARPBOX_RESUMABLE_CHUNK_PATH", ""),
 		},
 	}
+	cfg.DefaultSettings.ResumableUploadsEnabled = cfg.ResumableUploadsEnabled
+	cfg.DefaultSettings.ResumableChunkSizeMB = float64(cfg.ResumableChunkSize) / 1024 / 1024
+	cfg.DefaultSettings.ResumableRetentionHours = int(cfg.ResumableRetention / time.Hour)
 
 	if cfg.BaseURL == "" {
 		return Config{}, fmt.Errorf("WARPBOX_BASE_URL cannot be empty")
@@ -103,6 +119,12 @@ func Load() (Config, error) {
 	if cfg.MaxUploadSize <= 0 {
 		return Config{}, fmt.Errorf("WARPBOX_MAX_UPLOAD_SIZE_MB must be positive")
 	}
+	if cfg.ResumableChunkSize <= 0 {
+		return Config{}, fmt.Errorf("WARPBOX_RESUMABLE_CHUNK_MB must be positive")
+	}
+	if cfg.ResumableRetention <= 0 {
+		return Config{}, fmt.Errorf("WARPBOX_RESUMABLE_RETENTION_HOURS must be positive")
+	}
 	if !validUnlimitedMegabyteLimit(cfg.DefaultSettings.AnonymousMaxUploadMB) ||
 		!validUnlimitedMegabyteLimit(cfg.DefaultSettings.AnonymousDailyUploadMB) ||
 		!validUnlimitedMegabyteLimit(cfg.DefaultSettings.UserDailyUploadMB) ||

backend/libs/config/config_test.go

@@ -68,4 +68,13 @@ func TestLoadDefaultsUseLargeUploadFriendlyTimeouts(t *testing.T) {
 	if cfg.WriteTimeout != 0 {
 		t.Fatalf("WriteTimeout = %s, want 0 for long uploads", cfg.WriteTimeout)
 	}
+	if !cfg.ResumableUploadsEnabled {
+		t.Fatalf("ResumableUploadsEnabled = false, want true")
+	}
+	if cfg.ResumableChunkSize != 8*1024*1024 {
+		t.Fatalf("ResumableChunkSize = %d, want 8 MiB", cfg.ResumableChunkSize)
+	}
+	if cfg.ResumableRetention != 24*time.Hour {
+		t.Fatalf("ResumableRetention = %s, want 24h", cfg.ResumableRetention)
+	}
 }

backend/libs/handlers/admin.go

@@ -574,6 +574,7 @@ func (a *App) AdminSettingsPost(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	settings.AnonymousUploadsEnabled = r.FormValue("anonymous_uploads_enabled") == "on"
+	settings.ResumableUploadsEnabled = r.FormValue("resumable_uploads_enabled") == "on"
 	if value := parsePositiveInt(r.FormValue("usage_retention_days")); value > 0 {
 		settings.UsageRetentionDays = value
 	}
@@ -604,6 +605,16 @@ func (a *App) AdminSettingsPost(w http.ResponseWriter, r *http.Request) {
 	if value := parsePositiveInt(r.FormValue("short_window_seconds")); value > 0 {
 		settings.ShortWindowSeconds = value
 	}
+	if value := parsePositiveFloat(r.FormValue("resumable_chunk_size_mb")); value > 0 {
+		settings.ResumableChunkSizeMB = value
+	}
+	if value := parsePositiveInt(r.FormValue("resumable_retention_hours")); value > 0 {
+		settings.ResumableRetentionHours = value
+	}
+	if value := strings.TrimSpace(r.FormValue("resumable_chunk_mode")); value != "" {
+		settings.ResumableChunkMode = value
+	}
+	settings.ResumableChunkPath = strings.TrimSpace(r.FormValue("resumable_chunk_path"))
 	if value := r.FormValue("anonymous_storage_backend"); value != "" {
 		settings.AnonymousStorageBackend = value
 	}

backend/libs/handlers/app.go

@@ -141,6 +141,13 @@ func (a *App) RegisterRoutes(mux *http.ServeMux) {
 	mux.HandleFunc("GET /api/v1/schemas/upload-request.json", a.UploadRequestSchema)
 	mux.HandleFunc("GET /api/v1/schemas/upload-response.json", a.UploadResponseSchema)
 	mux.HandleFunc("POST /api/v1/upload", a.Upload)
+	mux.HandleFunc("POST /api/v1/uploads/resumable", a.CreateResumableUpload)
+	mux.HandleFunc("GET /api/v1/uploads/resumable/{sessionID}", a.ResumableUploadStatus)
+	mux.HandleFunc("POST /api/v1/uploads/resumable/{sessionID}/files", a.AddResumableFiles)
+	mux.HandleFunc("PUT /api/v1/uploads/resumable/{sessionID}/files/{fileID}/chunks/{index}", a.PutResumableChunk)
+	mux.HandleFunc("POST /api/v1/uploads/resumable/{sessionID}/complete", a.CompleteResumableUpload)
+	mux.HandleFunc("POST /api/v1/uploads/resumable/{sessionID}/complete-uploaded", a.CompleteUploadedResumableUpload)
+	mux.HandleFunc("DELETE /api/v1/uploads/resumable/{sessionID}", a.CancelResumableUpload)
 	mux.HandleFunc("GET /emoji/{pack}/{file}", a.EmojiAsset)
 	mux.Handle("GET /static/", a.Static())
 }

backend/libs/handlers/download.go

@@ -52,6 +52,7 @@ type fileView struct {
 	Reactions    []reactionView
 	ReactionMore int
 	Reacted      bool
+	Processing   bool
 }
 
 type reactionView struct {
@@ -101,6 +102,15 @@ func (a *App) DownloadPage(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 	locked := a.uploadService.IsProtected(box) && !a.isBoxUnlocked(r, box)
+	if isSocialPreviewBot(r) && !locked && len(box.Files) == 1 {
+		if box.Files[0].Processing {
+			http.Error(w, "file is still processing", http.StatusAccepted)
+			return
+		}
+		a.serveFileContent(w, r, box, box.Files[0], false)
+		a.logger.Info("single-file box served inline for social preview", withRequestLogAttrs(r, "source", "download", "severity", "user_activity", "code", 2008, "box_id", box.ID, "file_id", box.Files[0].ID)...)
+		return
+	}
 	visitorID := a.reactionVisitorID(w, r)
 	reactionsByFile, reactedByFile, err := a.reactionService.SummaryForBox(box.ID, visitorID)
 	if err != nil {
@@ -159,6 +169,15 @@ func (a *App) DownloadFile(w http.ResponseWriter, r *http.Request) {
 	}
 
 	locked := a.uploadService.IsProtected(box) && !a.isBoxUnlocked(r, box)
+	if isSocialPreviewBot(r) && !locked {
+		if file.Processing {
+			http.Error(w, "file is still processing", http.StatusAccepted)
+			return
+		}
+		a.serveFileContent(w, r, box, file, false)
+		a.logger.Info("file served inline for social preview", withRequestLogAttrs(r, "source", "download", "severity", "user_activity", "code", 2009, "box_id", box.ID, "file_id", file.ID)...)
+		return
+	}
 	view := a.fileView(box, file)
 	title := file.Name
 	description := fmt.Sprintf("%s shared via Warpbox", helpers.FormatBytes(file.Size))
@@ -193,6 +212,10 @@ func (a *App) DownloadFileContent(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "password required", http.StatusUnauthorized)
 		return
 	}
+	if file.Processing {
+		http.Error(w, "file is still processing", http.StatusAccepted)
+		return
+	}
 
 	a.serveFileContent(w, r, box, file, r.URL.Query().Get("inline") != "1")
 	a.logger.Info("file content served", withRequestLogAttrs(r, "source", "download", "severity", "user_activity", "code", 2005, "box_id", box.ID, "file_id", file.ID, "attachment", r.URL.Query().Get("inline") != "1")...)
@@ -373,6 +396,7 @@ func (a *App) fileViewWithReactions(box services.Box, file services.File, reacti
 		Reactions:    reactionViews,
 		ReactionMore: reactionOverflowCount(reactionViews),
 		Reacted:      reacted,
+		Processing:   file.Processing,
 	}
 }
 
@@ -583,3 +607,31 @@ func absoluteURL(r *http.Request, path string) string {
 	}
 	return fmt.Sprintf("%s://%s%s", scheme, r.Host, path)
 }
+
+func isSocialPreviewBot(r *http.Request) bool {
+	agent := strings.ToLower(r.UserAgent())
+	if agent == "" {
+		return false
+	}
+	bots := []string{
+		"discordbot",
+		"twitterbot",
+		"facebookexternalhit",
+		"telegrambot",
+		"whatsapp",
+		"slackbot",
+		"linkedinbot",
+		"skypeuripreview",
+		"embedly",
+		"pinterest",
+		"vkshare",
+		"mattermost",
+		"mastodon",
+	}
+	for _, bot := range bots {
+		if strings.Contains(agent, bot) {
+			return true
+		}
+	}
+	return false
+}

backend/libs/handlers/resumable.go

@@ -0,0 +1,427 @@
+package handlers
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+
+	"warpbox.dev/backend/libs/helpers"
+	"warpbox.dev/backend/libs/jobs"
+	"warpbox.dev/backend/libs/services"
+)
+
+type resumableCreateRequest struct {
+	Files             []services.ResumableFileInput `json:"files"`
+	MaxDays           int                           `json:"maxDays"`
+	ExpiresMinutes    int                           `json:"expiresMinutes"`
+	MaxDownloads      int                           `json:"maxDownloads"`
+	Password          string                        `json:"password"`
+	ObfuscateMetadata bool                          `json:"obfuscateMetadata"`
+	CollectionID      string                        `json:"collectionId"`
+}
+
+type resumableSessionResponse struct {
+	SessionID   string                   `json:"sessionId"`
+	ResumeToken string                   `json:"resumeToken,omitempty"`
+	ChunkSize   int64                    `json:"chunkSize"`
+	Status      string                   `json:"status"`
+	BoxID       string                   `json:"boxId,omitempty"`
+	ExpiresAt   string                   `json:"expiresAt"`
+	Files       []services.ResumableFile `json:"files"`
+}
+
+func (a *App) CreateResumableUpload(w http.ResponseWriter, r *http.Request) {
+	user, loggedIn, authErr := a.currentUserWithAuthError(r)
+	if authErr != nil {
+		a.logger.Warn("resumable upload rejected invalid bearer token", withRequestLogAttrs(r, "source", "user-upload", "severity", "warn", "code", 4011)...)
+		helpers.WriteJSONError(w, http.StatusUnauthorized, "invalid bearer token")
+		return
+	}
+	isAdminUpload := loggedIn && user.Role == services.UserRoleAdmin
+	settings, policy, ok := a.loadUploadPolicyForAPI(w, r, user, loggedIn)
+	if !ok {
+		return
+	}
+	if !settings.ResumableUploadsEnabled {
+		helpers.WriteJSONError(w, http.StatusForbidden, "resumable uploads are disabled")
+		return
+	}
+	if !loggedIn && !settings.AnonymousUploadsEnabled {
+		a.logger.Warn("resumable anonymous upload rejected disabled", withRequestLogAttrs(r, "source", "user-upload", "severity", "warn", "code", 4013)...)
+		helpers.WriteJSONError(w, http.StatusForbidden, "anonymous uploads are disabled")
+		return
+	}
+	rateKey := uploadRateKey(r, user, loggedIn)
+	if !isAdminUpload && policy.ShortRequests > 0 && !a.rateLimiter.Allow("upload:"+rateKey, policy.ShortRequests, policy.ShortWindow, time.Now().UTC()) {
+		a.logger.Warn("resumable upload rate limited", withRequestLogAttrs(r, "source", "user-upload", "severity", "warn", "code", 4291, "user_id", user.ID)...)
+		helpers.WriteJSONError(w, http.StatusTooManyRequests, "too many upload requests, please slow down")
+		return
+	}
+
+	var payload resumableCreateRequest
+	if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
+		helpers.WriteJSONError(w, http.StatusBadRequest, "upload session request could not be read")
+		return
+	}
+	fileSizes := make([]int64, 0, len(payload.Files))
+	var totalBytes int64
+	for _, file := range payload.Files {
+		fileSizes = append(fileSizes, file.Size)
+		totalBytes += file.Size
+	}
+	if !isAdminUpload {
+		if status, message := a.checkUploadPolicyForSizes(r, user, loggedIn, settings, policy, fileSizes, totalBytes); message != "" {
+			a.logger.Warn("resumable upload rejected by policy", withRequestLogAttrs(r, "source", "quota", "severity", "warn", "code", status, "user_id", user.ID, "message", message, "bytes", totalBytes, "files", len(payload.Files))...)
+			helpers.WriteJSONError(w, status, message)
+			return
+		}
+		if status, message := a.checkBoxCreationPolicy(r, user, loggedIn, policy); message != "" {
+			a.logger.Warn("resumable upload rejected by box policy", withRequestLogAttrs(r, "source", "quota", "severity", "warn", "code", status, "user_id", user.ID, "message", message, "bytes", totalBytes, "files", len(payload.Files))...)
+			helpers.WriteJSONError(w, status, message)
+			return
+		}
+	}
+
+	opts, err := a.resumableUploadOptions(r, payload, user, loggedIn, isAdminUpload, policy)
+	if err != nil {
+		helpers.WriteJSONError(w, http.StatusRequestEntityTooLarge, err.Error())
+		return
+	}
+	chunkSize := int64(settings.ResumableChunkSizeMB * 1024 * 1024)
+	retention := time.Duration(settings.ResumableRetentionHours) * time.Hour
+	session, err := a.uploadService.CreateResumableSession(payload.Files, opts, chunkSize, retention, resumableChunkRoot(settings))
+	if err != nil {
+		a.logger.Warn("resumable session create failed", withRequestLogAttrs(r, "source", "user-upload", "severity", "warn", "code", 4002, "user_id", user.ID, "error", err.Error())...)
+		helpers.WriteJSONError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+	a.logger.Info("resumable upload session created", withRequestLogAttrs(r, "source", "user-upload", "severity", "user_activity", "code", 2002, "user_id", user.ID, "session_id", session.ID, "files", len(session.Files), "bytes", totalBytes, "anonymous", !loggedIn)...)
+	helpers.WriteJSON(w, http.StatusCreated, resumableResponse(session))
+}
+
+func (a *App) ResumableUploadStatus(w http.ResponseWriter, r *http.Request) {
+	session, ok := a.authorizedResumableSession(w, r)
+	if !ok {
+		return
+	}
+	helpers.WriteJSON(w, http.StatusOK, resumableResponse(session))
+}
+
+func (a *App) AddResumableFiles(w http.ResponseWriter, r *http.Request) {
+	session, ok := a.authorizedResumableSession(w, r)
+	if !ok {
+		return
+	}
+	user, loggedIn, _ := a.currentUserWithAuthError(r)
+	isAdminUpload := loggedIn && user.Role == services.UserRoleAdmin
+	settings, policy, ok := a.loadUploadPolicyForAPI(w, r, user, loggedIn)
+	if !ok {
+		return
+	}
+	var payload struct {
+		Files []services.ResumableFileInput `json:"files"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
+		helpers.WriteJSONError(w, http.StatusBadRequest, "upload files request could not be read")
+		return
+	}
+	fileSizes := make([]int64, 0, len(session.Files)+len(payload.Files))
+	var totalBytes int64
+	for _, file := range session.Files {
+		fileSizes = append(fileSizes, file.Size)
+		totalBytes += file.Size
+	}
+	for _, file := range payload.Files {
+		fileSizes = append(fileSizes, file.Size)
+		totalBytes += file.Size
+	}
+	if !isAdminUpload {
+		if status, message := a.checkUploadPolicyForSizes(r, user, loggedIn, settings, policy, fileSizes, totalBytes); message != "" {
+			helpers.WriteJSONError(w, status, message)
+			return
+		}
+	}
+	updated, err := a.uploadService.AddResumableFiles(session.ID, payload.Files)
+	if err != nil {
+		helpers.WriteJSONError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+	a.logger.Info("resumable upload files added", withRequestLogAttrs(r, "source", "user-upload", "severity", "user_activity", "code", 2006, "session_id", session.ID, "added", len(updated.Files)-len(session.Files), "files", len(updated.Files))...)
+	helpers.WriteJSON(w, http.StatusOK, resumableResponse(updated))
+}
+
+func (a *App) PutResumableChunk(w http.ResponseWriter, r *http.Request) {
+	session, ok := a.authorizedResumableSession(w, r)
+	if !ok {
+		return
+	}
+	fileID := r.PathValue("fileID")
+	index, err := strconv.Atoi(r.PathValue("index"))
+	if err != nil {
+		helpers.WriteJSONError(w, http.StatusBadRequest, "chunk index is invalid")
+		return
+	}
+	updated, err := a.uploadService.PutResumableChunk(r.Context(), session.ID, fileID, index, r.Body)
+	if err != nil {
+		a.logger.Warn("resumable chunk failed", withRequestLogAttrs(r, "source", "user-upload", "severity", "warn", "code", 4003, "session_id", session.ID, "file_id", fileID, "chunk", index, "error", err.Error())...)
+		helpers.WriteJSONError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+	a.logger.Info("resumable chunk uploaded", withRequestLogAttrs(r, "source", "user-upload", "severity", "user_activity", "code", 2003, "session_id", session.ID, "file_id", fileID, "chunk", index)...)
+	helpers.WriteJSON(w, http.StatusOK, resumableResponse(updated))
+}
+
+func (a *App) CompleteResumableUpload(w http.ResponseWriter, r *http.Request) {
+	session, ok := a.authorizedResumableSession(w, r)
+	if !ok {
+		return
+	}
+	if session.Status == services.ResumableStatusCompleted || session.Status == services.ResumableStatusProcessing {
+		result, completed, err := a.uploadService.CompleteResumableSession(r.Context(), session.ID)
+		if err != nil {
+			a.logger.Warn("resumable upload completion replay failed", withRequestLogAttrs(r, "source", "user-upload", "severity", "warn", "code", 4004, "session_id", session.ID, "error", err.Error())...)
+			helpers.WriteJSONError(w, http.StatusBadRequest, err.Error())
+			return
+		}
+		a.logger.Info("resumable upload completion replayed", withRequestLogAttrs(r, "source", "user-upload", "severity", "user_activity", "code", 2004, "session_id", completed.ID, "box_id", result.BoxID, "files", len(result.Files))...)
+		helpers.WriteJSON(w, http.StatusOK, result)
+		return
+	}
+	user, loggedIn, _ := a.currentUserWithAuthError(r)
+	isAdminUpload := loggedIn && user.Role == services.UserRoleAdmin
+	settings, policy, ok := a.loadUploadPolicyForAPI(w, r, user, loggedIn)
+	if !ok {
+		return
+	}
+	fileSizes := make([]int64, 0, len(session.Files))
+	var totalBytes int64
+	for _, file := range session.Files {
+		fileSizes = append(fileSizes, file.Size)
+		totalBytes += file.Size
+	}
+	if !isAdminUpload {
+		if status, message := a.checkUploadPolicyForSizes(r, user, loggedIn, settings, policy, fileSizes, totalBytes); message != "" {
+			helpers.WriteJSONError(w, status, message)
+			return
+		}
+		if status, message := a.checkBoxCreationPolicy(r, user, loggedIn, policy); message != "" {
+			helpers.WriteJSONError(w, status, message)
+			return
+		}
+		if status, message := a.checkStorageBackendCapacity(session.Options.StorageBackendID, settings, totalBytes); message != "" {
+			helpers.WriteJSONError(w, status, message)
+			return
+		}
+	}
+	result, completed, err := a.uploadService.CreateProcessingBoxFromResumable(session.ID)
+	if err != nil {
+		a.logger.Warn("resumable upload complete failed", withRequestLogAttrs(r, "source", "user-upload", "severity", "warn", "code", 4004, "session_id", session.ID, "error", err.Error())...)
+		helpers.WriteJSONError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+	if !isAdminUpload {
+		if err := a.recordUploadUsage(r, user, loggedIn, totalBytes, 1); err != nil {
+			a.logger.Warn("failed to record resumable upload usage", "source", "quota", "severity", "warn", "code", 4404, "error", err.Error())
+		}
+		if err := a.settingsService.CleanupUsage(time.Now().UTC(), settings.UsageRetentionDays); err != nil {
+			a.logger.Warn("failed to cleanup upload usage", "source", "quota", "severity", "warn", "code", 4405, "error", err.Error())
+		}
+	}
+	a.finalizeResumableUploadAsync(completed.ID, result.BoxID)
+	a.logger.Info("resumable upload queued for processing", withRequestLogAttrs(r, "source", "user-upload", "severity", "user_activity", "code", 2004, "user_id", user.ID, "session_id", completed.ID, "box_id", result.BoxID, "files", len(result.Files), "bytes", totalBytes, "admin", isAdminUpload, "anonymous", !loggedIn)...)
+	helpers.WriteJSON(w, http.StatusCreated, result)
+}
+
+func (a *App) CompleteUploadedResumableUpload(w http.ResponseWriter, r *http.Request) {
+	session, ok := a.authorizedResumableSession(w, r)
+	if !ok {
+		return
+	}
+	user, loggedIn, _ := a.currentUserWithAuthError(r)
+	isAdminUpload := loggedIn && user.Role == services.UserRoleAdmin
+	settings, policy, ok := a.loadUploadPolicyForAPI(w, r, user, loggedIn)
+	if !ok {
+		return
+	}
+	fileSizes := make([]int64, 0, len(session.Files))
+	var totalBytes int64
+	var completeCount int
+	for _, file := range session.Files {
+		if len(file.UploadedChunks) != file.ChunkCount {
+			continue
+		}
+		fileSizes = append(fileSizes, file.Size)
+		totalBytes += file.Size
+		completeCount++
+	}
+	if completeCount == 0 {
+		helpers.WriteJSONError(w, http.StatusBadRequest, "no fully uploaded files to finish")
+		return
+	}
+	if !isAdminUpload {
+		if status, message := a.checkUploadPolicyForSizes(r, user, loggedIn, settings, policy, fileSizes, totalBytes); message != "" {
+			helpers.WriteJSONError(w, status, message)
+			return
+		}
+		if status, message := a.checkBoxCreationPolicy(r, user, loggedIn, policy); message != "" {
+			helpers.WriteJSONError(w, status, message)
+			return
+		}
+		if status, message := a.checkStorageBackendCapacity(session.Options.StorageBackendID, settings, totalBytes); message != "" {
+			helpers.WriteJSONError(w, status, message)
+			return
+		}
+	}
+	result, completed, err := a.uploadService.CompleteUploadedResumableSession(r.Context(), session.ID)
+	if err != nil {
+		a.logger.Warn("resumable partial complete failed", withRequestLogAttrs(r, "source", "user-upload", "severity", "warn", "code", 4005, "session_id", session.ID, "error", err.Error())...)
+		helpers.WriteJSONError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+	if !isAdminUpload {
+		if err := a.recordUploadUsage(r, user, loggedIn, totalBytes, 1); err != nil {
+			a.logger.Warn("failed to record partial resumable upload usage", "source", "quota", "severity", "warn", "code", 4406, "error", err.Error())
+		}
+		if err := a.settingsService.CleanupUsage(time.Now().UTC(), settings.UsageRetentionDays); err != nil {
+			a.logger.Warn("failed to cleanup upload usage", "source", "quota", "severity", "warn", "code", 4405, "error", err.Error())
+		}
+	}
+	jobs.GenerateThumbnailsForBoxAsync(a.uploadService, a.logger, result.BoxID)
+	a.logger.Info("resumable uploaded files completed", withRequestLogAttrs(r, "source", "user-upload", "severity", "user_activity", "code", 2007, "user_id", user.ID, "session_id", completed.ID, "box_id", result.BoxID, "files", len(result.Files), "bytes", totalBytes, "admin", isAdminUpload, "anonymous", !loggedIn)...)
+	helpers.WriteJSON(w, http.StatusCreated, result)
+}
+
+func (a *App) finalizeResumableUploadAsync(sessionID, boxID string) {
+	go func() {
+		a.logger.Info("resumable upload processing started", "source", "user-upload", "severity", "user_activity", "code", 2009, "session_id", sessionID, "box_id", boxID)
+		result, err := a.uploadService.FinalizeProcessingResumableSession(context.Background(), sessionID)
+		if err != nil {
+			a.logger.Warn("resumable upload processing failed", "source", "user-upload", "severity", "warn", "code", 4010, "session_id", sessionID, "box_id", boxID, "error", err.Error())
+			return
+		}
+		jobs.GenerateThumbnailsForBoxAsync(a.uploadService, a.logger, result.BoxID)
+		a.logger.Info("resumable upload processing completed", "source", "user-upload", "severity", "user_activity", "code", 2010, "session_id", sessionID, "box_id", result.BoxID, "files", len(result.Files))
+	}()
+}
+
+func resumableChunkRoot(settings services.UploadPolicySettings) string {
+	if settings.ResumableChunkMode != "custom" {
+		return ""
+	}
+	return strings.TrimSpace(settings.ResumableChunkPath)
+}
+
+func (a *App) CancelResumableUpload(w http.ResponseWriter, r *http.Request) {
+	session, ok := a.authorizedResumableSession(w, r)
+	if !ok {
+		return
+	}
+	if err := a.uploadService.CancelResumableSession(session.ID); err != nil {
+		helpers.WriteJSONError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+	a.logger.Info("resumable upload cancelled", withRequestLogAttrs(r, "source", "user-upload", "severity", "user_activity", "code", 2005, "session_id", session.ID)...)
+	w.WriteHeader(http.StatusNoContent)
+}
+
+func (a *App) authorizedResumableSession(w http.ResponseWriter, r *http.Request) (services.ResumableSession, bool) {
+	user, loggedIn, authErr := a.currentUserWithAuthError(r)
+	if authErr != nil {
+		helpers.WriteJSONError(w, http.StatusUnauthorized, "invalid bearer token")
+		return services.ResumableSession{}, false
+	}
+	session, err := a.uploadService.GetResumableSession(r.PathValue("sessionID"))
+	if err != nil {
+		helpers.WriteJSONError(w, http.StatusNotFound, "upload session not found")
+		return services.ResumableSession{}, false
+	}
+	if !a.uploadService.VerifyResumableToken(session, r.Header.Get("X-Warpbox-Resume-Token")) {
+		helpers.WriteJSONError(w, http.StatusUnauthorized, "upload session not found")
+		return services.ResumableSession{}, false
+	}
+	if loggedIn {
+		if session.Options.OwnerID != user.ID {
+			helpers.WriteJSONError(w, http.StatusForbidden, "upload session not found")
+			return services.ResumableSession{}, false
+		}
+		return session, true
+	}
+	if session.Options.OwnerID != "" || session.Options.CreatorIP != uploadClientIP(r) {
+		helpers.WriteJSONError(w, http.StatusForbidden, "upload session not found")
+		return services.ResumableSession{}, false
+	}
+	return session, true
+}
+
+func (a *App) loadUploadPolicyForAPI(w http.ResponseWriter, r *http.Request, user services.User, loggedIn bool) (services.UploadPolicySettings, services.EffectiveUploadPolicy, bool) {
+	settings, err := a.settingsService.UploadPolicy()
+	if err != nil {
+		a.logger.Error("failed to load upload policy", "source", "settings", "severity", "error", "code", 5006, "error", err.Error())
+		helpers.WriteJSONError(w, http.StatusInternalServerError, "upload policy could not be loaded")
+		return services.UploadPolicySettings{}, services.EffectiveUploadPolicy{}, false
+	}
+	return settings, a.effectiveUploadPolicy(settings, user, loggedIn), true
+}
+
+func (a *App) resumableUploadOptions(r *http.Request, payload resumableCreateRequest, user services.User, loggedIn, isAdminUpload bool, policy services.EffectiveUploadPolicy) (services.UploadOptions, error) {
+	var ownerID string
+	var collectionID string
+	if loggedIn {
+		ownerID = user.ID
+		collectionID = strings.TrimSpace(payload.CollectionID)
+		if !a.authService.CollectionOwnedBy(collectionID, user.ID) {
+			return services.UploadOptions{}, fmt.Errorf("collection not found")
+		}
+	}
+	unlimitedExpiry := isAdminUpload || policy.MaxDays < 0
+	rawMaxDays := payload.MaxDays
+	maxDays := rawMaxDays
+	if maxDays <= 0 {
+		maxDays = 7
+		if policy.MaxDays > 0 && policy.MaxDays < maxDays {
+			maxDays = policy.MaxDays
+		}
+	}
+	expiresMinutes := payload.ExpiresMinutes
+	if expiresMinutes < 0 || rawMaxDays < 0 {
+		if !unlimitedExpiry {
+			return services.UploadOptions{}, fmt.Errorf("expiration cannot exceed %d days", policy.MaxDays)
+		}
+		expiresMinutes = -1
+	} else if !unlimitedExpiry {
+		if maxDays > policy.MaxDays {
+			return services.UploadOptions{}, fmt.Errorf("expiration cannot exceed %d days", policy.MaxDays)
+		}
+		if expiresMinutes > 0 && expiresMinutes > policy.MaxDays*24*60 {
+			return services.UploadOptions{}, fmt.Errorf("expiration cannot exceed %d days", policy.MaxDays)
+		}
+	}
+	return services.UploadOptions{
+		MaxDays:           maxDays,
+		ExpiresInMinutes:  expiresMinutes,
+		MaxDownloads:      payload.MaxDownloads,
+		Password:          payload.Password,
+		ObfuscateMetadata: payload.ObfuscateMetadata,
+		OwnerID:           ownerID,
+		CollectionID:      collectionID,
+		SkipSizeLimit:     isAdminUpload || policy.MaxUploadMB < 0,
+		CreatorIP:         uploadClientIP(r),
+		StorageBackendID:  policy.StorageBackendID,
+	}, nil
+}
+
+func resumableResponse(session services.ResumableSession) resumableSessionResponse {
+	return resumableSessionResponse{
+		SessionID:   session.ID,
+		ResumeToken: session.ResumeToken,
+		ChunkSize:   session.ChunkSize,
+		Status:      session.Status,
+		BoxID:       session.BoxID,
+		ExpiresAt:   session.ExpiresAt.Format(time.RFC3339),
+		Files:       session.Files,
+	}
+}

backend/libs/handlers/upload.go

@@ -228,11 +228,22 @@ func (a *App) checkUploadPolicy(r *http.Request, user services.User, loggedIn bo
 	if len(files) == 0 {
 		return 0, ""
 	}
+	sizes := make([]int64, 0, len(files))
+	for _, file := range files {
+		sizes = append(sizes, file.Size)
+	}
+	return a.checkUploadPolicyForSizes(r, user, loggedIn, settings, policy, sizes, totalBytes)
+}
+
+func (a *App) checkUploadPolicyForSizes(r *http.Request, user services.User, loggedIn bool, settings services.UploadPolicySettings, policy services.EffectiveUploadPolicy, fileSizes []int64, totalBytes int64) (int, string) {
+	if len(fileSizes) == 0 {
+		return 0, ""
+	}
 	now := time.Now().UTC()
 	if policy.MaxUploadMB > 0 {
 		maxBytes := services.MegabytesToBytes(policy.MaxUploadMB)
-		for _, file := range files {
-			if file.Size > maxBytes {
+		for _, fileSize := range fileSizes {
+			if fileSize > maxBytes {
 				return http.StatusRequestEntityTooLarge, "file exceeds upload size limit"
 			}
 		}

backend/libs/handlers/upload_stage3_test.go

@@ -2,6 +2,7 @@ package handlers
 
 import (
 	"bytes"
+	"context"
 	"encoding/json"
 	"io"
 	"log/slog"
@@ -10,8 +11,10 @@ import (
 	"net/http/httptest"
 	"os"
 	"path/filepath"
+	"strconv"
 	"strings"
 	"testing"
+	"time"
 
 	"warpbox.dev/backend/libs/config"
 	"warpbox.dev/backend/libs/services"
@@ -103,6 +106,385 @@ func TestUploadTextResponseReturnsOnlyBoxURL(t *testing.T) {
 	}
 }
 
+func TestSocialPreviewBotGetsRawSingleFileBox(t *testing.T) {
+	app, cleanup := newTestApp(t)
+	defer cleanup()
+	payload := uploadThroughApp(t, app)
+
+	request := httptest.NewRequest(http.MethodGet, "/d/"+payload.BoxID, nil)
+	request.Header.Set("User-Agent", "Discordbot/2.0")
+	request.SetPathValue("boxID", payload.BoxID)
+	response := httptest.NewRecorder()
+	app.DownloadPage(response, request)
+
+	if response.Code != http.StatusOK {
+		t.Fatalf("status = %d, body = %s", response.Code, response.Body.String())
+	}
+	if strings.Contains(response.Body.String(), "Shared files on Warpbox") {
+		t.Fatalf("social preview bot received HTML download page")
+	}
+	if response.Body.String() != "hello" {
+		t.Fatalf("social preview body = %q", response.Body.String())
+	}
+}
+
+func TestSocialPreviewBotGetsRawFilePreview(t *testing.T) {
+	app, cleanup := newTestApp(t)
+	defer cleanup()
+	payload := uploadThroughApp(t, app)
+
+	request := httptest.NewRequest(http.MethodGet, "/d/"+payload.BoxID+"/f/"+payload.Files[0].ID, nil)
+	request.Header.Set("User-Agent", "TelegramBot")
+	request.SetPathValue("boxID", payload.BoxID)
+	request.SetPathValue("fileID", payload.Files[0].ID)
+	response := httptest.NewRecorder()
+	app.DownloadFile(response, request)
+
+	if response.Code != http.StatusOK {
+		t.Fatalf("status = %d, body = %s", response.Code, response.Body.String())
+	}
+	if strings.Contains(response.Body.String(), "preview-title") {
+		t.Fatalf("social preview bot received HTML preview page")
+	}
+	if response.Body.String() != "hello" {
+		t.Fatalf("social preview body = %q", response.Body.String())
+	}
+}
+
+func TestResumableUploadFlowCreatesNormalBox(t *testing.T) {
+	app, cleanup := newTestApp(t)
+	defer cleanup()
+
+	createBody := `{"files":[{"name":"note.txt","size":11,"contentType":"text/plain"}],"expiresMinutes":60}`
+	createRequest := httptest.NewRequest(http.MethodPost, "/api/v1/uploads/resumable", strings.NewReader(createBody))
+	createRequest.Header.Set("Accept", "application/json")
+	createResponse := httptest.NewRecorder()
+	app.CreateResumableUpload(createResponse, createRequest)
+	if createResponse.Code != http.StatusCreated {
+		t.Fatalf("create status = %d, body = %s", createResponse.Code, createResponse.Body.String())
+	}
+	var session struct {
+		SessionID   string `json:"sessionId"`
+		ResumeToken string `json:"resumeToken"`
+		ChunkSize   int64  `json:"chunkSize"`
+		Files       []struct {
+			ID             string `json:"id"`
+			ChunkCount     int    `json:"chunkCount"`
+			UploadedChunks []int  `json:"uploadedChunks"`
+		} `json:"files"`
+	}
+	if err := json.Unmarshal(createResponse.Body.Bytes(), &session); err != nil {
+		t.Fatalf("json.Unmarshal session returned error: %v", err)
+	}
+	if session.SessionID == "" || session.ResumeToken == "" || session.ChunkSize != 4 || len(session.Files) != 1 || session.Files[0].ChunkCount != 3 {
+		t.Fatalf("unexpected session response: %+v", session)
+	}
+
+	chunks := map[int]string{1: "o wo", 0: "hell", 2: "rld"}
+	for index, body := range chunks {
+		request := httptest.NewRequest(http.MethodPut, "/api/v1/uploads/resumable/"+session.SessionID+"/files/"+session.Files[0].ID+"/chunks/"+strconv.Itoa(index), strings.NewReader(body))
+		request.SetPathValue("sessionID", session.SessionID)
+		request.SetPathValue("fileID", session.Files[0].ID)
+		request.SetPathValue("index", strconv.Itoa(index))
+		request.Header.Set("X-Warpbox-Resume-Token", session.ResumeToken)
+		response := httptest.NewRecorder()
+		app.PutResumableChunk(response, request)
+		if response.Code != http.StatusOK {
+			t.Fatalf("chunk %d status = %d, body = %s", index, response.Code, response.Body.String())
+		}
+	}
+
+	completeRequest := httptest.NewRequest(http.MethodPost, "/api/v1/uploads/resumable/"+session.SessionID+"/complete", nil)
+	completeRequest.SetPathValue("sessionID", session.SessionID)
+	completeRequest.Header.Set("X-Warpbox-Resume-Token", session.ResumeToken)
+	completeResponse := httptest.NewRecorder()
+	app.CompleteResumableUpload(completeResponse, completeRequest)
+	if completeResponse.Code != http.StatusCreated {
+		t.Fatalf("complete status = %d, body = %s", completeResponse.Code, completeResponse.Body.String())
+	}
+	var payload services.UploadResult
+	if err := json.Unmarshal(completeResponse.Body.Bytes(), &payload); err != nil {
+		t.Fatalf("json.Unmarshal result returned error: %v", err)
+	}
+	replayRequest := httptest.NewRequest(http.MethodPost, "/api/v1/uploads/resumable/"+session.SessionID+"/complete", nil)
+	replayRequest.SetPathValue("sessionID", session.SessionID)
+	replayRequest.Header.Set("X-Warpbox-Resume-Token", session.ResumeToken)
+	replayResponse := httptest.NewRecorder()
+	app.CompleteResumableUpload(replayResponse, replayRequest)
+	if replayResponse.Code != http.StatusOK {
+		t.Fatalf("complete replay status = %d, body = %s", replayResponse.Code, replayResponse.Body.String())
+	}
+	var replayPayload services.UploadResult
+	if err := json.Unmarshal(replayResponse.Body.Bytes(), &replayPayload); err != nil {
+		t.Fatalf("json.Unmarshal replay result returned error: %v", err)
+	}
+	if replayPayload.BoxID != payload.BoxID || replayPayload.BoxURL == "" {
+		t.Fatalf("unexpected replay result: %+v, original: %+v", replayPayload, payload)
+	}
+	box := waitForProcessedBox(t, app, payload.BoxID)
+	if len(box.Files) != 1 || box.Files[0].Name != "note.txt" || box.Files[0].Size != 11 {
+		t.Fatalf("unexpected box files: %+v", box.Files)
+	}
+	object, err := app.uploadService.OpenFileObject(context.Background(), box, box.Files[0])
+	if err != nil {
+		t.Fatalf("OpenFileObject returned error: %v", err)
+	}
+	data, err := io.ReadAll(object.Body)
+	object.Body.Close()
+	if err != nil {
+		t.Fatalf("ReadAll returned error: %v", err)
+	}
+	if string(data) != "hello world" {
+		t.Fatalf("uploaded body = %q", string(data))
+	}
+}
+
+func TestResumableUploadRequiresAllChunks(t *testing.T) {
+	app, cleanup := newTestApp(t)
+	defer cleanup()
+
+	createRequest := httptest.NewRequest(http.MethodPost, "/api/v1/uploads/resumable", strings.NewReader(`{"files":[{"name":"note.txt","size":8,"contentType":"text/plain"}]}`))
+	createResponse := httptest.NewRecorder()
+	app.CreateResumableUpload(createResponse, createRequest)
+	if createResponse.Code != http.StatusCreated {
+		t.Fatalf("create status = %d, body = %s", createResponse.Code, createResponse.Body.String())
+	}
+	var session struct {
+		SessionID   string `json:"sessionId"`
+		ResumeToken string `json:"resumeToken"`
+		Files       []struct {
+			ID string `json:"id"`
+		} `json:"files"`
+	}
+	if err := json.Unmarshal(createResponse.Body.Bytes(), &session); err != nil {
+		t.Fatalf("json.Unmarshal session returned error: %v", err)
+	}
+	chunkRequest := httptest.NewRequest(http.MethodPut, "/api/v1/uploads/resumable/"+session.SessionID+"/files/"+session.Files[0].ID+"/chunks/0", strings.NewReader("hell"))
+	chunkRequest.SetPathValue("sessionID", session.SessionID)
+	chunkRequest.SetPathValue("fileID", session.Files[0].ID)
+	chunkRequest.SetPathValue("index", "0")
+	chunkRequest.Header.Set("X-Warpbox-Resume-Token", session.ResumeToken)
+	chunkResponse := httptest.NewRecorder()
+	app.PutResumableChunk(chunkResponse, chunkRequest)
+	if chunkResponse.Code != http.StatusOK {
+		t.Fatalf("chunk status = %d, body = %s", chunkResponse.Code, chunkResponse.Body.String())
+	}
+
+	completeRequest := httptest.NewRequest(http.MethodPost, "/api/v1/uploads/resumable/"+session.SessionID+"/complete", nil)
+	completeRequest.SetPathValue("sessionID", session.SessionID)
+	completeRequest.Header.Set("X-Warpbox-Resume-Token", session.ResumeToken)
+	completeResponse := httptest.NewRecorder()
+	app.CompleteResumableUpload(completeResponse, completeRequest)
+	if completeResponse.Code != http.StatusBadRequest {
+		t.Fatalf("complete status = %d, body = %s", completeResponse.Code, completeResponse.Body.String())
+	}
+}
+
+func TestResumableStatusRequiresResumeToken(t *testing.T) {
+	app, cleanup := newTestApp(t)
+	defer cleanup()
+
+	createRequest := httptest.NewRequest(http.MethodPost, "/api/v1/uploads/resumable", strings.NewReader(`{"files":[{"name":"note.txt","size":4,"contentType":"text/plain"}]}`))
+	createResponse := httptest.NewRecorder()
+	app.CreateResumableUpload(createResponse, createRequest)
+	if createResponse.Code != http.StatusCreated {
+		t.Fatalf("create status = %d, body = %s", createResponse.Code, createResponse.Body.String())
+	}
+	var session struct {
+		SessionID   string `json:"sessionId"`
+		ResumeToken string `json:"resumeToken"`
+	}
+	if err := json.Unmarshal(createResponse.Body.Bytes(), &session); err != nil {
+		t.Fatalf("json.Unmarshal session returned error: %v", err)
+	}
+
+	missing := httptest.NewRequest(http.MethodGet, "/api/v1/uploads/resumable/"+session.SessionID, nil)
+	missing.SetPathValue("sessionID", session.SessionID)
+	missingResponse := httptest.NewRecorder()
+	app.ResumableUploadStatus(missingResponse, missing)
+	if missingResponse.Code != http.StatusUnauthorized {
+		t.Fatalf("missing token status = %d, body = %s", missingResponse.Code, missingResponse.Body.String())
+	}
+
+	wrong := httptest.NewRequest(http.MethodGet, "/api/v1/uploads/resumable/"+session.SessionID, nil)
+	wrong.SetPathValue("sessionID", session.SessionID)
+	wrong.Header.Set("X-Warpbox-Resume-Token", "wrong")
+	wrongResponse := httptest.NewRecorder()
+	app.ResumableUploadStatus(wrongResponse, wrong)
+	if wrongResponse.Code != http.StatusUnauthorized {
+		t.Fatalf("wrong token status = %d, body = %s", wrongResponse.Code, wrongResponse.Body.String())
+	}
+
+	valid := httptest.NewRequest(http.MethodGet, "/api/v1/uploads/resumable/"+session.SessionID, nil)
+	valid.SetPathValue("sessionID", session.SessionID)
+	valid.Header.Set("X-Warpbox-Resume-Token", session.ResumeToken)
+	validResponse := httptest.NewRecorder()
+	app.ResumableUploadStatus(validResponse, valid)
+	if validResponse.Code != http.StatusOK {
+		t.Fatalf("valid token status = %d, body = %s", validResponse.Code, validResponse.Body.String())
+	}
+	if strings.Contains(validResponse.Body.String(), "resumeTokenHash") {
+		t.Fatalf("status response leaked token hash: %s", validResponse.Body.String())
+	}
+}
+
+func TestResumableUploadCanAddFilesToExistingSession(t *testing.T) {
+	app, cleanup := newTestApp(t)
+	defer cleanup()
+
+	createBody := `{"files":[{"name":"one.txt","size":4,"contentType":"text/plain","fingerprint":"one"}],"expiresMinutes":60}`
+	createRequest := httptest.NewRequest(http.MethodPost, "/api/v1/uploads/resumable", strings.NewReader(createBody))
+	createResponse := httptest.NewRecorder()
+	app.CreateResumableUpload(createResponse, createRequest)
+	if createResponse.Code != http.StatusCreated {
+		t.Fatalf("create status = %d, body = %s", createResponse.Code, createResponse.Body.String())
+	}
+	var session struct {
+		SessionID   string `json:"sessionId"`
+		ResumeToken string `json:"resumeToken"`
+		Files       []struct {
+			ID string `json:"id"`
+		} `json:"files"`
+	}
+	if err := json.Unmarshal(createResponse.Body.Bytes(), &session); err != nil {
+		t.Fatalf("json.Unmarshal session returned error: %v", err)
+	}
+	firstChunk := httptest.NewRequest(http.MethodPut, "/api/v1/uploads/resumable/"+session.SessionID+"/files/"+session.Files[0].ID+"/chunks/0", strings.NewReader("one!"))
+	firstChunk.SetPathValue("sessionID", session.SessionID)
+	firstChunk.SetPathValue("fileID", session.Files[0].ID)
+	firstChunk.SetPathValue("index", "0")
+	firstChunk.Header.Set("X-Warpbox-Resume-Token", session.ResumeToken)
+	firstChunkResponse := httptest.NewRecorder()
+	app.PutResumableChunk(firstChunkResponse, firstChunk)
+	if firstChunkResponse.Code != http.StatusOK {
+		t.Fatalf("first chunk status = %d, body = %s", firstChunkResponse.Code, firstChunkResponse.Body.String())
+	}
+
+	addRequest := httptest.NewRequest(http.MethodPost, "/api/v1/uploads/resumable/"+session.SessionID+"/files", strings.NewReader(`{"files":[{"name":"two.txt","size":4,"contentType":"text/plain","fingerprint":"two"}]}`))
+	addRequest.SetPathValue("sessionID", session.SessionID)
+	addRequest.Header.Set("X-Warpbox-Resume-Token", session.ResumeToken)
+	addResponse := httptest.NewRecorder()
+	app.AddResumableFiles(addResponse, addRequest)
+	if addResponse.Code != http.StatusOK {
+		t.Fatalf("add status = %d, body = %s", addResponse.Code, addResponse.Body.String())
+	}
+	var updated struct {
+		Files []struct {
+			ID             string `json:"id"`
+			Name           string `json:"name"`
+			UploadedChunks []int  `json:"uploadedChunks"`
+		} `json:"files"`
+	}
+	if err := json.Unmarshal(addResponse.Body.Bytes(), &updated); err != nil {
+		t.Fatalf("json.Unmarshal updated returned error: %v", err)
+	}
+	if len(updated.Files) != 2 || len(updated.Files[0].UploadedChunks) != 1 {
+		t.Fatalf("unexpected updated session: %+v", updated)
+	}
+	secondChunk := httptest.NewRequest(http.MethodPut, "/api/v1/uploads/resumable/"+session.SessionID+"/files/"+updated.Files[1].ID+"/chunks/0", strings.NewReader("two!"))
+	secondChunk.SetPathValue("sessionID", session.SessionID)
+	secondChunk.SetPathValue("fileID", updated.Files[1].ID)
+	secondChunk.SetPathValue("index", "0")
+	secondChunk.Header.Set("X-Warpbox-Resume-Token", session.ResumeToken)
+	secondChunkResponse := httptest.NewRecorder()
+	app.PutResumableChunk(secondChunkResponse, secondChunk)
+	if secondChunkResponse.Code != http.StatusOK {
+		t.Fatalf("second chunk status = %d, body = %s", secondChunkResponse.Code, secondChunkResponse.Body.String())
+	}
+	completeRequest := httptest.NewRequest(http.MethodPost, "/api/v1/uploads/resumable/"+session.SessionID+"/complete", nil)
+	completeRequest.SetPathValue("sessionID", session.SessionID)
+	completeRequest.Header.Set("X-Warpbox-Resume-Token", session.ResumeToken)
+	completeResponse := httptest.NewRecorder()
+	app.CompleteResumableUpload(completeResponse, completeRequest)
+	if completeResponse.Code != http.StatusCreated {
+		t.Fatalf("complete status = %d, body = %s", completeResponse.Code, completeResponse.Body.String())
+	}
+	var payload services.UploadResult
+	if err := json.Unmarshal(completeResponse.Body.Bytes(), &payload); err != nil {
+		t.Fatalf("json.Unmarshal result returned error: %v", err)
+	}
+	box, err := app.uploadService.GetBox(payload.BoxID)
+	if err != nil {
+		t.Fatalf("GetBox returned error: %v", err)
+	}
+	if len(box.Files) != 2 {
+		t.Fatalf("box file count = %d, want 2", len(box.Files))
+	}
+}
+
+func TestResumableCompleteUploadedRequiresTokenAndKeepsFinishedFiles(t *testing.T) {
+	app, cleanup := newTestApp(t)
+	defer cleanup()
+
+	createBody := `{"files":[{"name":"done.txt","size":4,"contentType":"text/plain","fingerprint":"done"},{"name":"partial.txt","size":8,"contentType":"text/plain","fingerprint":"partial"}],"expiresMinutes":60}`
+	createRequest := httptest.NewRequest(http.MethodPost, "/api/v1/uploads/resumable", strings.NewReader(createBody))
+	createResponse := httptest.NewRecorder()
+	app.CreateResumableUpload(createResponse, createRequest)
+	if createResponse.Code != http.StatusCreated {
+		t.Fatalf("create status = %d, body = %s", createResponse.Code, createResponse.Body.String())
+	}
+	var session struct {
+		SessionID   string `json:"sessionId"`
+		ResumeToken string `json:"resumeToken"`
+		Files       []struct {
+			ID string `json:"id"`
+		} `json:"files"`
+	}
+	if err := json.Unmarshal(createResponse.Body.Bytes(), &session); err != nil {
+		t.Fatalf("json.Unmarshal session returned error: %v", err)
+	}
+	for _, chunk := range []struct {
+		fileIndex int
+		index     string
+		body      string
+	}{
+		{fileIndex: 0, index: "0", body: "done"},
+		{fileIndex: 1, index: "0", body: "part"},
+	} {
+		request := httptest.NewRequest(http.MethodPut, "/api/v1/uploads/resumable/"+session.SessionID+"/files/"+session.Files[chunk.fileIndex].ID+"/chunks/"+chunk.index, strings.NewReader(chunk.body))
+		request.SetPathValue("sessionID", session.SessionID)
+		request.SetPathValue("fileID", session.Files[chunk.fileIndex].ID)
+		request.SetPathValue("index", chunk.index)
+		request.Header.Set("X-Warpbox-Resume-Token", session.ResumeToken)
+		response := httptest.NewRecorder()
+		app.PutResumableChunk(response, request)
+		if response.Code != http.StatusOK {
+			t.Fatalf("chunk status = %d, body = %s", response.Code, response.Body.String())
+		}
+	}
+
+	missing := httptest.NewRequest(http.MethodPost, "/api/v1/uploads/resumable/"+session.SessionID+"/complete-uploaded", nil)
+	missing.SetPathValue("sessionID", session.SessionID)
+	missingResponse := httptest.NewRecorder()
+	app.CompleteUploadedResumableUpload(missingResponse, missing)
+	if missingResponse.Code != http.StatusUnauthorized {
+		t.Fatalf("missing token status = %d, body = %s", missingResponse.Code, missingResponse.Body.String())
+	}
+
+	complete := httptest.NewRequest(http.MethodPost, "/api/v1/uploads/resumable/"+session.SessionID+"/complete-uploaded", nil)
+	complete.SetPathValue("sessionID", session.SessionID)
+	complete.Header.Set("X-Warpbox-Resume-Token", session.ResumeToken)
+	completeResponse := httptest.NewRecorder()
+	app.CompleteUploadedResumableUpload(completeResponse, complete)
+	if completeResponse.Code != http.StatusCreated {
+		t.Fatalf("complete-uploaded status = %d, body = %s", completeResponse.Code, completeResponse.Body.String())
+	}
+	var payload services.UploadResult
+	if err := json.Unmarshal(completeResponse.Body.Bytes(), &payload); err != nil {
+		t.Fatalf("json.Unmarshal result returned error: %v", err)
+	}
+	box, err := app.uploadService.GetBox(payload.BoxID)
+	if err != nil {
+		t.Fatalf("GetBox returned error: %v", err)
+	}
+	if len(box.Files) != 1 || box.Files[0].Name != "done.txt" {
+		t.Fatalf("complete-uploaded box files = %+v", box.Files)
+	}
+	if _, err := app.uploadService.GetResumableSession(session.SessionID); !os.IsNotExist(err) {
+		t.Fatalf("GetResumableSession after complete-uploaded error = %v, want os.ErrNotExist", err)
+	}
+}
+
 func TestManageBoxAndDeleteFlow(t *testing.T) {
 	app, cleanup := newTestApp(t)
 	defer cleanup()
@@ -214,13 +596,16 @@ func newTestApp(t *testing.T) (*App, func()) {
 
 	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
 	cfg := config.Config{
-		AppName:       "warpbox.dev",
-		AppVersion:    "test",
-		BaseURL:       "http://example.test",
-		DataDir:       filepath.Join(root, "data"),
-		StaticDir:     staticDir,
-		TemplateDir:   templateDir,
-		MaxUploadSize: 1024 * 1024,
+		AppName:                 "warpbox.dev",
+		AppVersion:              "test",
+		BaseURL:                 "http://example.test",
+		DataDir:                 filepath.Join(root, "data"),
+		StaticDir:               staticDir,
+		TemplateDir:             templateDir,
+		MaxUploadSize:           1024 * 1024,
+		ResumableUploadsEnabled: true,
+		ResumableChunkSize:      4,
+		ResumableRetention:      time.Hour,
 		DefaultSettings: config.SettingsDefaults{
 			AnonymousUploadsEnabled: true,
 			AnonymousMaxUploadMB:    1,
@@ -228,6 +613,10 @@ func newTestApp(t *testing.T) (*App, func()) {
 			UserDailyUploadMB:       8,
 			DefaultUserStorageMB:    16,
 			UsageRetentionDays:      30,
+			ResumableUploadsEnabled: true,
+			ResumableChunkSizeMB:    0.000003814697265625,
+			ResumableRetentionHours: 1,
+			ResumableChunkMode:      "same",
 		},
 	}
 	service, err := services.NewUploadService(cfg.MaxUploadSize, cfg.DataDir, cfg.BaseURL, logger)
@@ -342,6 +731,31 @@ func tokenFromURL(t *testing.T, value string) string {
 	return parts[len(parts)-1]
 }
 
+func waitForProcessedBox(t *testing.T, app *App, boxID string) services.Box {
+	t.Helper()
+	var box services.Box
+	for i := 0; i < 50; i++ {
+		next, err := app.uploadService.GetBox(boxID)
+		if err != nil {
+			t.Fatalf("GetBox returned error: %v", err)
+		}
+		box = next
+		processing := false
+		for _, file := range box.Files {
+			if file.Processing {
+				processing = true
+				break
+			}
+		}
+		if !processing {
+			return box
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+	t.Fatalf("box %s was still processing: %+v", boxID, box.Files)
+	return box
+}
+
 func copyDir(src, dst string) error {
 	return filepath.WalkDir(src, func(path string, d os.DirEntry, err error) error {
 		if err != nil {

backend/libs/jobs/cleanup.go

@@ -22,6 +22,14 @@ func newCleanupJob(cfg config.Config, logger *slog.Logger, uploadService *servic
 			if cleaned > 0 {
 				logger.Info("cleanup job complete", "source", "housekeeping", "severity", "user_activity", "code", 2202, "cleaned", cleaned)
 			}
+			cleanedUploads, err := uploadService.CleanupExpiredResumableSessions(time.Now().UTC())
+			if err != nil {
+				logger.Warn("resumable upload cleanup failed", "source", "housekeeping", "severity", "warn", "code", 4204, "error", err.Error())
+				return
+			}
+			if cleanedUploads > 0 {
+				logger.Info("resumable uploads cleaned", "source", "housekeeping", "severity", "user_activity", "code", 2204, "cleaned", cleanedUploads)
+			}
 			if banService != nil {
 				cleanedEvents, err := banService.CleanupAbuseEvents(time.Now().UTC())
 				if err != nil {
@@ -37,7 +45,12 @@ func newCleanupJob(cfg config.Config, logger *slog.Logger, uploadService *servic
 }
 
 func RunCleanupNow(uploadService *services.UploadService, logger *slog.Logger) (int, error) {
-	return cleanupUnavailableBoxes(uploadService, logger)
+	cleaned, err := cleanupUnavailableBoxes(uploadService, logger)
+	if err != nil {
+		return cleaned, err
+	}
+	cleanedUploads, err := uploadService.CleanupExpiredResumableSessions(time.Now().UTC())
+	return cleaned + cleanedUploads, err
 }
 
 func cleanupUnavailableBoxes(uploadService *services.UploadService, logger *slog.Logger) (int, error) {

backend/libs/services/resumable.go

@@ -0,0 +1,735 @@
+package services
+
+import (
+	"context"
+	"crypto/sha256"
+	"crypto/subtle"
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+	"time"
+
+	"go.etcd.io/bbolt"
+)
+
+var resumableUploadsBucket = []byte("resumable_uploads")
+
+const (
+	ResumableStatusUploading  = "uploading"
+	ResumableStatusProcessing = "processing"
+	ResumableStatusCompleted  = "completed"
+	ResumableStatusCancelled  = "cancelled"
+)
+
+type ResumableFileInput struct {
+	Name        string `json:"name"`
+	Size        int64  `json:"size"`
+	ContentType string `json:"contentType"`
+	Fingerprint string `json:"fingerprint,omitempty"`
+}
+
+type ResumableSession struct {
+	ID              string          `json:"id"`
+	Options         UploadOptions   `json:"options"`
+	Files           []ResumableFile `json:"files"`
+	ChunkSize       int64           `json:"chunkSize"`
+	Status          string          `json:"status"`
+	BoxID           string          `json:"boxId,omitempty"`
+	ResumeTokenHash string          `json:"resumeTokenHash,omitempty"`
+	ResumeToken     string          `json:"-"`
+	ChunkRoot       string          `json:"chunkRoot,omitempty"`
+	CreatedAt       time.Time       `json:"createdAt"`
+	UpdatedAt       time.Time       `json:"updatedAt"`
+	ExpiresAt       time.Time       `json:"expiresAt"`
+}
+
+type ResumableFile struct {
+	ID             string `json:"id"`
+	Name           string `json:"name"`
+	Size           int64  `json:"size"`
+	ContentType    string `json:"contentType"`
+	Fingerprint    string `json:"fingerprint,omitempty"`
+	ChunkCount     int    `json:"chunkCount"`
+	UploadedChunks []int  `json:"uploadedChunks"`
+}
+
+func (s *UploadService) ensureResumableBucket() error {
+	return s.db.Update(func(tx *bbolt.Tx) error {
+		_, err := tx.CreateBucketIfNotExists(resumableUploadsBucket)
+		return err
+	})
+}
+
+func (s *UploadService) CreateResumableSession(files []ResumableFileInput, opts UploadOptions, chunkSize int64, retention time.Duration, chunkRoot string) (ResumableSession, error) {
+	if len(files) == 0 {
+		return ResumableSession{}, fmt.Errorf("no files were uploaded")
+	}
+	if chunkSize <= 0 {
+		return ResumableSession{}, fmt.Errorf("chunk size must be positive")
+	}
+	if retention <= 0 {
+		return ResumableSession{}, fmt.Errorf("retention must be positive")
+	}
+	if strings.TrimSpace(opts.Password) != "" {
+		opts.PasswordSalt, opts.PasswordHash = hashPassword(opts.Password)
+		opts.Password = ""
+	}
+	sessionFiles, err := s.resumableFilesFromInput(files, opts, chunkSize, nil)
+	if err != nil {
+		return ResumableSession{}, err
+	}
+	now := time.Now().UTC()
+	resumeToken := randomID(32)
+	sessionID := randomID(12)
+	session := ResumableSession{
+		ID:              sessionID,
+		Options:         opts,
+		Files:           sessionFiles,
+		ChunkSize:       chunkSize,
+		Status:          ResumableStatusUploading,
+		ResumeTokenHash: resumableTokenHash(sessionID, resumeToken),
+		ResumeToken:     resumeToken,
+		ChunkRoot:       strings.TrimSpace(chunkRoot),
+		CreatedAt:       now,
+		UpdatedAt:       now,
+		ExpiresAt:       now.Add(retention),
+	}
+	if err := s.saveResumableSession(session); err != nil {
+		return ResumableSession{}, err
+	}
+	return session, nil
+}
+
+func (s *UploadService) VerifyResumableToken(session ResumableSession, token string) bool {
+	if session.ResumeTokenHash == "" || strings.TrimSpace(token) == "" {
+		return false
+	}
+	hash := resumableTokenHash(session.ID, token)
+	return subtle.ConstantTimeCompare([]byte(hash), []byte(session.ResumeTokenHash)) == 1
+}
+
+func (s *UploadService) AddResumableFiles(sessionID string, files []ResumableFileInput) (ResumableSession, error) {
+	if len(files) == 0 {
+		return s.GetResumableSession(sessionID)
+	}
+	session, err := s.GetResumableSession(sessionID)
+	if err != nil {
+		return ResumableSession{}, err
+	}
+	if err := resumableSessionWritable(session); err != nil {
+		return ResumableSession{}, err
+	}
+	existing := make(map[string]bool)
+	for _, file := range session.Files {
+		existing[resumableFileKey(file.Name, file.Size, file.Fingerprint)] = true
+	}
+	newFiles, err := s.resumableFilesFromInput(files, session.Options, session.ChunkSize, existing)
+	if err != nil {
+		return ResumableSession{}, err
+	}
+	if len(newFiles) == 0 {
+		return session, nil
+	}
+	session.Files = append(session.Files, newFiles...)
+	session.UpdatedAt = time.Now().UTC()
+	if err := s.saveResumableSession(session); err != nil {
+		return ResumableSession{}, err
+	}
+	return session, nil
+}
+
+func (s *UploadService) GetResumableSession(id string) (ResumableSession, error) {
+	var session ResumableSession
+	err := s.db.View(func(tx *bbolt.Tx) error {
+		bucket := tx.Bucket(resumableUploadsBucket)
+		if bucket == nil {
+			return os.ErrNotExist
+		}
+		data := bucket.Get([]byte(id))
+		if data == nil {
+			return os.ErrNotExist
+		}
+		return json.Unmarshal(data, &session)
+	})
+	if err != nil {
+		return ResumableSession{}, err
+	}
+	return session, nil
+}
+
+func (s *UploadService) PutResumableChunk(ctx context.Context, sessionID, fileID string, index int, body io.Reader) (ResumableSession, error) {
+	session, err := s.GetResumableSession(sessionID)
+	if err != nil {
+		return ResumableSession{}, err
+	}
+	if err := resumableSessionWritable(session); err != nil {
+		return ResumableSession{}, err
+	}
+	fileIndex := -1
+	for i, file := range session.Files {
+		if file.ID == fileID {
+			fileIndex = i
+			break
+		}
+	}
+	if fileIndex < 0 {
+		return ResumableSession{}, os.ErrNotExist
+	}
+	file := session.Files[fileIndex]
+	if index < 0 || index >= file.ChunkCount {
+		return ResumableSession{}, fmt.Errorf("chunk index is invalid")
+	}
+	expectedSize := expectedChunkSize(file.Size, session.ChunkSize, index)
+	chunkDir := s.resumableFileDirFor(session, file.ID)
+	if err := os.MkdirAll(chunkDir, 0o755); err != nil {
+		return ResumableSession{}, err
+	}
+	chunkPath := s.resumableChunkPathFor(session, file.ID, index)
+	tempPath := chunkPath + ".tmp"
+	target, err := os.OpenFile(tempPath, os.O_CREATE|os.O_TRUNC|os.O_WRONLY, 0o600)
+	if err != nil {
+		return ResumableSession{}, err
+	}
+	written, copyErr := io.Copy(target, io.LimitReader(body, expectedSize+1))
+	closeErr := target.Close()
+	if copyErr != nil {
+		_ = os.Remove(tempPath)
+		return ResumableSession{}, copyErr
+	}
+	if closeErr != nil {
+		_ = os.Remove(tempPath)
+		return ResumableSession{}, closeErr
+	}
+	if written != expectedSize {
+		_ = os.Remove(tempPath)
+		return ResumableSession{}, fmt.Errorf("chunk size mismatch")
+	}
+	if err := os.Rename(tempPath, chunkPath); err != nil {
+		_ = os.Remove(tempPath)
+		return ResumableSession{}, err
+	}
+	session.Files[fileIndex].UploadedChunks = addChunkIndex(session.Files[fileIndex].UploadedChunks, index)
+	session.UpdatedAt = time.Now().UTC()
+	if err := s.saveResumableSession(session); err != nil {
+		return ResumableSession{}, err
+	}
+	return session, nil
+}
+
+func (s *UploadService) CompleteResumableSession(ctx context.Context, sessionID string) (UploadResult, ResumableSession, error) {
+	session, err := s.GetResumableSession(sessionID)
+	if err != nil {
+		return UploadResult{}, ResumableSession{}, err
+	}
+	if (session.Status == ResumableStatusCompleted || session.Status == ResumableStatusProcessing) && session.BoxID != "" {
+		box, err := s.GetBox(session.BoxID)
+		if err != nil {
+			return UploadResult{}, ResumableSession{}, err
+		}
+		return s.resultForBox(box, ""), session, nil
+	}
+	if err := resumableSessionWritable(session); err != nil {
+		return UploadResult{}, ResumableSession{}, err
+	}
+	staged, err := s.resumableIncomingFiles(session)
+	if err != nil {
+		return UploadResult{}, ResumableSession{}, err
+	}
+
+	result, err := s.CreateBoxFromIncomingContext(ctx, staged, session.Options)
+	if err != nil {
+		return UploadResult{}, ResumableSession{}, err
+	}
+	if err := os.RemoveAll(s.resumableSessionDirFor(session)); err != nil {
+		return UploadResult{}, ResumableSession{}, err
+	}
+	session.Status = ResumableStatusCompleted
+	session.BoxID = result.BoxID
+	session.UpdatedAt = time.Now().UTC()
+	if err := s.saveResumableSession(session); err != nil {
+		return UploadResult{}, ResumableSession{}, err
+	}
+	return result, session, nil
+}
+
+func (s *UploadService) CreateProcessingBoxFromResumable(sessionID string) (UploadResult, ResumableSession, error) {
+	session, err := s.GetResumableSession(sessionID)
+	if err != nil {
+		return UploadResult{}, ResumableSession{}, err
+	}
+	if (session.Status == ResumableStatusCompleted || session.Status == ResumableStatusProcessing) && session.BoxID != "" {
+		box, err := s.GetBox(session.BoxID)
+		if err != nil {
+			return UploadResult{}, ResumableSession{}, err
+		}
+		return s.resultForBox(box, ""), session, nil
+	}
+	if err := resumableSessionWritable(session); err != nil {
+		return UploadResult{}, ResumableSession{}, err
+	}
+	if _, err := s.resumableIncomingFiles(session); err != nil {
+		return UploadResult{}, ResumableSession{}, err
+	}
+
+	now := time.Now().UTC()
+	expiresAt := now.AddDate(0, 0, 7)
+	if session.Options.ExpiresInMinutes < 0 || session.Options.MaxDays < 0 {
+		expiresAt = now.AddDate(100, 0, 0)
+	} else if session.Options.ExpiresInMinutes > 0 {
+		expiresAt = now.Add(time.Duration(session.Options.ExpiresInMinutes) * time.Minute)
+	} else if session.Options.MaxDays > 0 {
+		expiresAt = now.Add(time.Duration(session.Options.MaxDays) * 24 * time.Hour)
+	}
+
+	box := Box{
+		ID:               randomID(10),
+		OwnerID:          strings.TrimSpace(session.Options.OwnerID),
+		CollectionID:     strings.TrimSpace(session.Options.CollectionID),
+		CreatorIP:        strings.TrimSpace(session.Options.CreatorIP),
+		StorageBackendID: normalizeBackendID(session.Options.StorageBackendID),
+		CreatedAt:        now,
+		ExpiresAt:        expiresAt,
+		MaxDownloads:     session.Options.MaxDownloads,
+		Obfuscate:        session.Options.ObfuscateMetadata && (strings.TrimSpace(session.Options.Password) != "" || strings.TrimSpace(session.Options.PasswordHash) != ""),
+		Files:            make([]File, 0, len(session.Files)),
+	}
+	deleteToken := randomID(32)
+	box.DeleteTokenHash = deleteTokenHash(box.ID, deleteToken)
+	if strings.TrimSpace(session.Options.PasswordHash) != "" {
+		box.PasswordSalt = session.Options.PasswordSalt
+		box.PasswordHash = session.Options.PasswordHash
+	} else if strings.TrimSpace(session.Options.Password) != "" {
+		salt, hash := hashPassword(session.Options.Password)
+		box.PasswordSalt = salt
+		box.PasswordHash = hash
+	}
+
+	for _, incoming := range session.Files {
+		fileID := randomID(8)
+		storedName := "@each@" + fileID + strings.ToLower(filepath.Ext(incoming.Name))
+		objectKey := boxObjectKey(box.ID, storedName)
+		contentType := incoming.ContentType
+		if contentType == "" {
+			contentType = "application/octet-stream"
+		}
+		box.Files = append(box.Files, File{
+			ID:          fileID,
+			Name:        filepath.Base(incoming.Name),
+			StoredName:  storedName,
+			Size:        incoming.Size,
+			ContentType: contentType,
+			PreviewKind: previewKind(contentType),
+			ObjectKey:   objectKey,
+			Processing:  true,
+			UploadedAt:  now,
+		})
+	}
+	if err := s.saveBoxRecord(box); err != nil {
+		return UploadResult{}, ResumableSession{}, err
+	}
+	session.Status = ResumableStatusProcessing
+	session.BoxID = box.ID
+	session.UpdatedAt = time.Now().UTC()
+	if err := s.saveResumableSession(session); err != nil {
+		return UploadResult{}, ResumableSession{}, err
+	}
+	return s.resultForBox(box, deleteToken), session, nil
+}
+
+func (s *UploadService) FinalizeProcessingResumableSession(ctx context.Context, sessionID string) (UploadResult, error) {
+	session, err := s.GetResumableSession(sessionID)
+	if err != nil {
+		return UploadResult{}, err
+	}
+	if session.Status == ResumableStatusCompleted && session.BoxID != "" {
+		box, err := s.GetBox(session.BoxID)
+		if err != nil {
+			return UploadResult{}, err
+		}
+		return s.resultForBox(box, ""), nil
+	}
+	if session.Status != ResumableStatusProcessing || session.BoxID == "" {
+		return UploadResult{}, fmt.Errorf("upload session is not processing")
+	}
+	box, err := s.GetBox(session.BoxID)
+	if err != nil {
+		return UploadResult{}, err
+	}
+	staged, err := s.resumableIncomingFiles(session)
+	if err != nil {
+		return UploadResult{}, err
+	}
+	if len(staged) != len(box.Files) {
+		return UploadResult{}, fmt.Errorf("processing file count mismatch")
+	}
+	backend, err := s.storage.Backend(box.StorageBackendID)
+	if err != nil {
+		return UploadResult{}, err
+	}
+	for i, incoming := range staged {
+		source, err := incoming.Open()
+		if err != nil {
+			return UploadResult{}, err
+		}
+		file := box.Files[i]
+		if err := s.writeUploadedObject(ctx, backend, file.ObjectKey, source, incoming.Size(), 0, incoming.ContentType()); err != nil {
+			source.Close()
+			_ = backend.Delete(context.Background(), file.ObjectKey)
+			box.Files[i].ProcessingError = err.Error()
+			_ = s.saveBoxRecord(box)
+			return UploadResult{}, err
+		}
+		source.Close()
+		box.Files[i].Processing = false
+		box.Files[i].ProcessingError = ""
+		box.Files[i].UploadedAt = time.Now().UTC()
+		if err := s.saveBoxRecord(box); err != nil {
+			return UploadResult{}, err
+		}
+	}
+	if err := s.writeBoxMetadata(box); err != nil {
+		s.logger.Warn("box metadata write failed after resumable processing", "source", "storage", "severity", "warn", "code", 4020, "box_id", box.ID, "error", err.Error())
+	}
+	if err := os.RemoveAll(s.resumableSessionDirFor(session)); err != nil {
+		return UploadResult{}, err
+	}
+	session.Status = ResumableStatusCompleted
+	session.UpdatedAt = time.Now().UTC()
+	if err := s.saveResumableSession(session); err != nil {
+		return UploadResult{}, err
+	}
+	return s.resultForBox(box, ""), nil
+}
+
+func (s *UploadService) CompleteUploadedResumableSession(ctx context.Context, sessionID string) (UploadResult, ResumableSession, error) {
+	session, err := s.GetResumableSession(sessionID)
+	if err != nil {
+		return UploadResult{}, ResumableSession{}, err
+	}
+	if err := resumableSessionWritable(session); err != nil {
+		return UploadResult{}, ResumableSession{}, err
+	}
+	completeFiles := make([]ResumableFile, 0, len(session.Files))
+	for _, file := range session.Files {
+		if resumableFileComplete(file) {
+			completeFiles = append(completeFiles, file)
+		}
+	}
+	if len(completeFiles) == 0 {
+		return UploadResult{}, ResumableSession{}, fmt.Errorf("no fully uploaded files to finish")
+	}
+	partial := session
+	partial.Files = completeFiles
+	staged, err := s.resumableIncomingFiles(partial)
+	if err != nil {
+		return UploadResult{}, ResumableSession{}, err
+	}
+
+	result, err := s.CreateBoxFromIncomingContext(ctx, staged, session.Options)
+	if err != nil {
+		return UploadResult{}, ResumableSession{}, err
+	}
+	if err := os.RemoveAll(s.resumableSessionDirFor(session)); err != nil {
+		return UploadResult{}, ResumableSession{}, err
+	}
+	session.Status = ResumableStatusCompleted
+	session.BoxID = result.BoxID
+	session.Files = completeFiles
+	session.UpdatedAt = time.Now().UTC()
+	if err := s.deleteResumableSession(session.ID); err != nil {
+		return UploadResult{}, ResumableSession{}, err
+	}
+	return result, session, nil
+}
+
+func (s *UploadService) CancelResumableSession(sessionID string) error {
+	session, err := s.GetResumableSession(sessionID)
+	if err != nil {
+		return err
+	}
+	if err := os.RemoveAll(s.resumableSessionDirFor(session)); err != nil {
+		return err
+	}
+	return s.deleteResumableSession(session.ID)
+}
+
+func (s *UploadService) CleanupExpiredResumableSessions(now time.Time) (int, error) {
+	candidates := make([]ResumableSession, 0)
+	err := s.db.View(func(tx *bbolt.Tx) error {
+		bucket := tx.Bucket(resumableUploadsBucket)
+		if bucket == nil {
+			return nil
+		}
+		return bucket.ForEach(func(_, value []byte) error {
+			var session ResumableSession
+			if err := json.Unmarshal(value, &session); err != nil {
+				return err
+			}
+			if session.Status == ResumableStatusCompleted ||
+				session.Status == ResumableStatusCancelled ||
+				(session.Status == ResumableStatusUploading && !session.ExpiresAt.After(now)) {
+				candidates = append(candidates, session)
+			}
+			return nil
+		})
+	})
+	if err != nil {
+		return 0, err
+	}
+	for _, session := range candidates {
+		if err := os.RemoveAll(s.resumableSessionDirFor(session)); err != nil {
+			return 0, err
+		}
+	}
+	err = s.db.Update(func(tx *bbolt.Tx) error {
+		bucket := tx.Bucket(resumableUploadsBucket)
+		if bucket == nil {
+			return nil
+		}
+		for _, session := range candidates {
+			if err := bucket.Delete([]byte(session.ID)); err != nil {
+				return err
+			}
+		}
+		return nil
+	})
+	return len(candidates), err
+}
+
+func (s *UploadService) deleteResumableSession(sessionID string) error {
+	return s.db.Update(func(tx *bbolt.Tx) error {
+		bucket := tx.Bucket(resumableUploadsBucket)
+		if bucket == nil {
+			return nil
+		}
+		return bucket.Delete([]byte(sessionID))
+	})
+}
+
+func (s *UploadService) saveResumableSession(session ResumableSession) error {
+	if err := s.ensureResumableBucket(); err != nil {
+		return err
+	}
+	return s.db.Update(func(tx *bbolt.Tx) error {
+		data, err := json.Marshal(session)
+		if err != nil {
+			return err
+		}
+		return tx.Bucket(resumableUploadsBucket).Put([]byte(session.ID), data)
+	})
+}
+
+func (s *UploadService) resumableFilesFromInput(files []ResumableFileInput, opts UploadOptions, chunkSize int64, existing map[string]bool) ([]ResumableFile, error) {
+	sessionFiles := make([]ResumableFile, 0, len(files))
+	for _, file := range files {
+		file.Name = filepath.Base(strings.TrimSpace(file.Name))
+		if file.Name == "." || file.Name == "" {
+			return nil, fmt.Errorf("file name is required")
+		}
+		if file.Size < 0 {
+			return nil, fmt.Errorf("file size is invalid")
+		}
+		fingerprint := strings.TrimSpace(file.Fingerprint)
+		key := resumableFileKey(file.Name, file.Size, fingerprint)
+		if existing != nil && existing[key] {
+			continue
+		}
+		if !opts.SkipSizeLimit {
+			if err := s.ValidateSize(file.Size); err != nil {
+				return nil, err
+			}
+		}
+		chunks := int((file.Size + chunkSize - 1) / chunkSize)
+		if chunks == 0 {
+			chunks = 1
+		}
+		sessionFiles = append(sessionFiles, ResumableFile{
+			ID:          randomID(8),
+			Name:        file.Name,
+			Size:        file.Size,
+			ContentType: strings.TrimSpace(file.ContentType),
+			Fingerprint: fingerprint,
+			ChunkCount:  chunks,
+		})
+		if existing != nil {
+			existing[key] = true
+		}
+	}
+	return sessionFiles, nil
+}
+
+func resumableFileKey(name string, size int64, fingerprint string) string {
+	return strings.TrimSpace(fingerprint) + "|" + filepath.Base(strings.TrimSpace(name)) + "|" + fmt.Sprintf("%d", size)
+}
+
+type resumableIncomingFile struct {
+	service *UploadService
+	session ResumableSession
+	file    ResumableFile
+}
+
+func (f resumableIncomingFile) Name() string {
+	return f.file.Name
+}
+
+func (f resumableIncomingFile) Size() int64 {
+	return f.file.Size
+}
+
+func (f resumableIncomingFile) ContentType() string {
+	return f.file.ContentType
+}
+
+func (f resumableIncomingFile) Open() (io.ReadCloser, error) {
+	return &resumableChunkReader{
+		service: f.service,
+		session: f.session,
+		file:    f.file,
+	}, nil
+}
+
+type resumableChunkReader struct {
+	service *UploadService
+	session ResumableSession
+	file    ResumableFile
+	index   int
+	current *os.File
+}
+
+func (r *resumableChunkReader) Read(p []byte) (int, error) {
+	for {
+		if r.current == nil {
+			if r.index >= r.file.ChunkCount {
+				return 0, io.EOF
+			}
+			chunk, err := os.Open(r.service.resumableChunkPathFor(r.session, r.file.ID, r.index))
+			if err != nil {
+				return 0, err
+			}
+			r.current = chunk
+		}
+		n, err := r.current.Read(p)
+		if err == io.EOF {
+			if closeErr := r.current.Close(); closeErr != nil {
+				r.current = nil
+				return n, closeErr
+			}
+			r.current = nil
+			r.index++
+			if n > 0 {
+				return n, nil
+			}
+			continue
+		}
+		return n, err
+	}
+}
+
+func (r *resumableChunkReader) Close() error {
+	if r.current == nil {
+		return nil
+	}
+	err := r.current.Close()
+	r.current = nil
+	return err
+}
+
+func (s *UploadService) resumableIncomingFiles(session ResumableSession) ([]IncomingFile, error) {
+	staged := make([]IncomingFile, 0, len(session.Files))
+	for _, file := range session.Files {
+		if len(file.UploadedChunks) != file.ChunkCount {
+			return nil, fmt.Errorf("file %s is missing chunks", file.Name)
+		}
+		var written int64
+		for i := 0; i < file.ChunkCount; i++ {
+			info, err := os.Stat(s.resumableChunkPathFor(session, file.ID, i))
+			if err != nil {
+				return nil, fmt.Errorf("file %s is missing chunks", file.Name)
+			}
+			written += info.Size()
+		}
+		if written != file.Size {
+			return nil, fmt.Errorf("chunk size total mismatch")
+		}
+		staged = append(staged, resumableIncomingFile{
+			service: s,
+			session: session,
+			file:    file,
+		})
+	}
+	return staged, nil
+}
+
+func resumableSessionWritable(session ResumableSession) error {
+	if session.Status != ResumableStatusUploading {
+		return fmt.Errorf("upload session is not active")
+	}
+	if !session.ExpiresAt.After(time.Now().UTC()) {
+		return fmt.Errorf("upload session expired")
+	}
+	return nil
+}
+
+func resumableFileComplete(file ResumableFile) bool {
+	return file.ChunkCount > 0 && len(file.UploadedChunks) == file.ChunkCount
+}
+
+func expectedChunkSize(fileSize, chunkSize int64, index int) int64 {
+	offset := int64(index) * chunkSize
+	remaining := fileSize - offset
+	if remaining < 0 {
+		return 0
+	}
+	if remaining > chunkSize {
+		return chunkSize
+	}
+	return remaining
+}
+
+func addChunkIndex(chunks []int, index int) []int {
+	for _, chunk := range chunks {
+		if chunk == index {
+			return chunks
+		}
+	}
+	chunks = append(chunks, index)
+	sort.Ints(chunks)
+	return chunks
+}
+
+func resumableTokenHash(sessionID, token string) string {
+	sum := sha256.Sum256([]byte("warpbox-resumable:" + sessionID + ":" + token))
+	return hex.EncodeToString(sum[:])
+}
+
+func (s *UploadService) resumableSessionDir(sessionID string) string {
+	return filepath.Join(s.dataDir, "tmp", "uploads", sessionID)
+}
+
+func (s *UploadService) resumableSessionDirFor(session ResumableSession) string {
+	if strings.TrimSpace(session.ChunkRoot) != "" {
+		return filepath.Join(session.ChunkRoot, session.ID)
+	}
+	return s.resumableSessionDir(session.ID)
+}
+
+func (s *UploadService) resumableFileDir(sessionID, fileID string) string {
+	return filepath.Join(s.resumableSessionDir(sessionID), fileID)
+}
+
+func (s *UploadService) resumableFileDirFor(session ResumableSession, fileID string) string {
+	return filepath.Join(s.resumableSessionDirFor(session), fileID)
+}
+
+func (s *UploadService) resumableChunkPath(sessionID, fileID string, index int) string {
+	return filepath.Join(s.resumableFileDir(sessionID, fileID), fmt.Sprintf("%06d.part", index))
+}
+
+func (s *UploadService) resumableChunkPathFor(session ResumableSession, fileID string, index int) string {
+	return filepath.Join(s.resumableFileDirFor(session, fileID), fmt.Sprintf("%06d.part", index))
+}

backend/libs/services/settings.go

@@ -37,6 +37,11 @@ type UploadPolicySettings struct {
 	ShortWindowSeconds      int     `json:"shortWindowSeconds"`
 	AnonymousStorageBackend string  `json:"anonymousStorageBackend"`
 	UserStorageBackend      string  `json:"userStorageBackend"`
+	ResumableUploadsEnabled bool    `json:"resumableUploadsEnabled"`
+	ResumableChunkSizeMB    float64 `json:"resumableChunkSizeMb"`
+	ResumableRetentionHours int     `json:"resumableRetentionHours"`
+	ResumableChunkMode      string  `json:"resumableChunkMode"`
+	ResumableChunkPath      string  `json:"resumableChunkPath"`
 }
 
 type UsageRecord struct {
@@ -89,6 +94,11 @@ func NewSettingsService(db *bbolt.DB, defaults config.SettingsDefaults) (*Settin
 			ShortWindowSeconds:      defaults.ShortWindowSeconds,
 			AnonymousStorageBackend: defaults.AnonymousStorageBackend,
 			UserStorageBackend:      defaults.UserStorageBackend,
+			ResumableUploadsEnabled: defaults.ResumableUploadsEnabled,
+			ResumableChunkSizeMB:    defaults.ResumableChunkSizeMB,
+			ResumableRetentionHours: defaults.ResumableRetentionHours,
+			ResumableChunkMode:      defaults.ResumableChunkMode,
+			ResumableChunkPath:      defaults.ResumableChunkPath,
 		},
 	}
 	service.defaults = service.withBuiltinDefaultGaps(service.defaults)
@@ -143,6 +153,15 @@ func (s *SettingsService) withBuiltinDefaultGaps(settings UploadPolicySettings)
 	if strings.TrimSpace(settings.UserStorageBackend) == "" {
 		settings.UserStorageBackend = StorageBackendLocal
 	}
+	if settings.ResumableChunkSizeMB <= 0 {
+		settings.ResumableChunkSizeMB = 8
+	}
+	if settings.ResumableRetentionHours <= 0 {
+		settings.ResumableRetentionHours = 24
+	}
+	if strings.TrimSpace(settings.ResumableChunkMode) == "" {
+		settings.ResumableChunkMode = "same"
+	}
 	return settings
 }
 
@@ -156,6 +175,13 @@ func (s *SettingsService) UploadPolicy() (UploadPolicySettings, error) {
 		if err := json.Unmarshal(data, &settings); err != nil {
 			return err
 		}
+		var raw map[string]json.RawMessage
+		if err := json.Unmarshal(data, &raw); err != nil {
+			return err
+		}
+		if _, ok := raw["resumableUploadsEnabled"]; !ok {
+			settings.ResumableUploadsEnabled = s.defaults.ResumableUploadsEnabled
+		}
 		settings = s.withDefaultGaps(settings)
 		return nil
 	})
@@ -217,6 +243,15 @@ func (s *SettingsService) withDefaultGaps(settings UploadPolicySettings) UploadP
 	if strings.TrimSpace(settings.UserStorageBackend) == "" {
 		settings.UserStorageBackend = s.defaults.UserStorageBackend
 	}
+	if settings.ResumableChunkSizeMB <= 0 {
+		settings.ResumableChunkSizeMB = s.defaults.ResumableChunkSizeMB
+	}
+	if settings.ResumableRetentionHours <= 0 {
+		settings.ResumableRetentionHours = s.defaults.ResumableRetentionHours
+	}
+	if strings.TrimSpace(settings.ResumableChunkMode) == "" {
+		settings.ResumableChunkMode = s.defaults.ResumableChunkMode
+	}
 	return settings
 }
 
@@ -422,6 +457,18 @@ func (s *SettingsService) validate(settings UploadPolicySettings) error {
 	if settings.ShortWindowRequests <= 0 || settings.ShortWindowSeconds <= 0 {
 		return fmt.Errorf("short-window rate limits must be positive")
 	}
+	if settings.ResumableChunkSizeMB <= 0 {
+		return fmt.Errorf("resumable chunk size must be positive")
+	}
+	if settings.ResumableRetentionHours <= 0 {
+		return fmt.Errorf("resumable retention must be positive")
+	}
+	if settings.ResumableChunkMode != "same" && settings.ResumableChunkMode != "custom" {
+		return fmt.Errorf("resumable chunk storage mode is invalid")
+	}
+	if settings.ResumableChunkMode == "custom" && strings.TrimSpace(settings.ResumableChunkPath) == "" {
+		return fmt.Errorf("custom resumable chunk path is required")
+	}
 	return nil
 }
 

backend/libs/services/upload.go

@@ -42,6 +42,8 @@ type UploadOptions struct {
 	ExpiresInMinutes  int
 	MaxDownloads      int
 	Password          string
+	PasswordSalt      string
+	PasswordHash      string
 	ObfuscateMetadata bool
 	OwnerID           string
 	CollectionID      string
@@ -50,6 +52,56 @@ type UploadOptions struct {
 	StorageBackendID  string
 }
 
+type IncomingFile interface {
+	Name() string
+	Size() int64
+	ContentType() string
+	Open() (io.ReadCloser, error)
+}
+
+type multipartIncomingFile struct {
+	header *multipart.FileHeader
+}
+
+func (f multipartIncomingFile) Name() string {
+	return f.header.Filename
+}
+
+func (f multipartIncomingFile) Size() int64 {
+	return f.header.Size
+}
+
+func (f multipartIncomingFile) ContentType() string {
+	return f.header.Header.Get("Content-Type")
+}
+
+func (f multipartIncomingFile) Open() (io.ReadCloser, error) {
+	return f.header.Open()
+}
+
+type StagedUploadFile struct {
+	Filename string
+	FileSize int64
+	MIMEType string
+	Path     string
+}
+
+func (f StagedUploadFile) Name() string {
+	return f.Filename
+}
+
+func (f StagedUploadFile) Size() int64 {
+	return f.FileSize
+}
+
+func (f StagedUploadFile) ContentType() string {
+	return f.MIMEType
+}
+
+func (f StagedUploadFile) Open() (io.ReadCloser, error) {
+	return os.Open(f.Path)
+}
+
 type Box struct {
 	ID               string    `json:"id"`
 	OwnerID          string    `json:"ownerId,omitempty"`
@@ -78,6 +130,8 @@ type File struct {
 	Thumbnail          string    `json:"thumbnail,omitempty"`
 	ObjectKey          string    `json:"objectKey,omitempty"`
 	ThumbnailObjectKey string    `json:"thumbnailObjectKey,omitempty"`
+	Processing         bool      `json:"processing,omitempty"`
+	ProcessingError    string    `json:"processingError,omitempty"`
 	UploadedAt         time.Time `json:"uploadedAt"`
 }
 
@@ -98,6 +152,7 @@ type ResultFile struct {
 	Size         string `json:"size"`
 	URL          string `json:"url"`
 	ThumbnailURL string `json:"thumbnailUrl"`
+	Processing   bool   `json:"processing,omitempty"`
 }
 
 type AdminStats struct {
@@ -198,6 +253,14 @@ func (s *UploadService) ValidateSize(size int64) error {
 }
 
 func (s *UploadService) CreateBox(files []*multipart.FileHeader, opts UploadOptions) (UploadResult, error) {
+	return s.CreateBoxFromIncoming(multipartIncomingFiles(files), opts)
+}
+
+func (s *UploadService) CreateBoxFromIncoming(files []IncomingFile, opts UploadOptions) (UploadResult, error) {
+	return s.CreateBoxFromIncomingContext(context.Background(), files, opts)
+}
+
+func (s *UploadService) CreateBoxFromIncomingContext(ctx context.Context, files []IncomingFile, opts UploadOptions) (UploadResult, error) {
 	if len(files) == 0 {
 		return UploadResult{}, fmt.Errorf("no files were uploaded")
 	}
@@ -232,13 +295,16 @@ func (s *UploadService) CreateBox(files []*multipart.FileHeader, opts UploadOpti
 	}
 	deleteToken := randomID(32)
 	box.DeleteTokenHash = deleteTokenHash(box.ID, deleteToken)
-	if strings.TrimSpace(opts.Password) != "" {
+	if strings.TrimSpace(opts.PasswordHash) != "" {
+		box.PasswordSalt = opts.PasswordSalt
+		box.PasswordHash = opts.PasswordHash
+	} else if strings.TrimSpace(opts.Password) != "" {
 		salt, hash := hashPassword(opts.Password)
 		box.PasswordSalt = salt
 		box.PasswordHash = hash
 	}
 
-	if err := s.writeFilesToBox(&box, files, opts); err != nil {
+	if err := s.writeIncomingFilesToBox(ctx, &box, files, opts); err != nil {
 		return UploadResult{}, err
 	}
 
@@ -261,6 +327,10 @@ func (s *UploadService) CreateBox(files []*multipart.FileHeader, opts UploadOpti
 // selection into a single box). The box keeps its original expiry, password and
 // other settings; only the new files are written.
 func (s *UploadService) AppendFiles(boxID string, files []*multipart.FileHeader, opts UploadOptions) (UploadResult, error) {
+	return s.AppendIncomingFiles(boxID, multipartIncomingFiles(files), opts)
+}
+
+func (s *UploadService) AppendIncomingFiles(boxID string, files []IncomingFile, opts UploadOptions) (UploadResult, error) {
 	if len(files) == 0 {
 		return UploadResult{}, fmt.Errorf("no files were uploaded")
 	}
@@ -268,7 +338,7 @@ func (s *UploadService) AppendFiles(boxID string, files []*multipart.FileHeader,
 	if err != nil {
 		return UploadResult{}, err
 	}
-	if err := s.writeFilesToBox(&box, files, opts); err != nil {
+	if err := s.writeIncomingFilesToBox(context.Background(), &box, files, opts); err != nil {
 		return UploadResult{}, err
 	}
 	if err := s.SaveBox(box); err != nil {
@@ -289,14 +359,26 @@ func (s *UploadService) AppendFiles(boxID string, files []*multipart.FileHeader,
 // appends the file metadata to box.Files. The box's StorageBackendID determines
 // where files land, so it works for both new and existing boxes.
 func (s *UploadService) writeFilesToBox(box *Box, files []*multipart.FileHeader, opts UploadOptions) error {
+	return s.writeIncomingFilesToBox(context.Background(), box, multipartIncomingFiles(files), opts)
+}
+
+func multipartIncomingFiles(files []*multipart.FileHeader) []IncomingFile {
+	incoming := make([]IncomingFile, 0, len(files))
+	for _, file := range files {
+		incoming = append(incoming, multipartIncomingFile{header: file})
+	}
+	return incoming
+}
+
+func (s *UploadService) writeIncomingFilesToBox(ctx context.Context, box *Box, files []IncomingFile, opts UploadOptions) error {
 	backend, err := s.storage.Backend(box.StorageBackendID)
 	if err != nil {
 		return err
 	}
 
-	for _, header := range files {
+	for _, incoming := range files {
 		if !opts.SkipSizeLimit {
-			if err := s.ValidateSize(header.Size); err != nil {
+			if err := s.ValidateSize(incoming.Size()); err != nil {
 				return err
 			}
 		}
@@ -306,15 +388,15 @@ func (s *UploadService) writeFilesToBox(box *Box, files []*multipart.FileHeader,
 			maxSize = 0
 		}
 
-		file, err := header.Open()
+		file, err := incoming.Open()
 		if err != nil {
 			return err
 		}
 
 		fileID := randomID(8)
-		storedName := "@each@" + fileID + strings.ToLower(filepath.Ext(header.Filename))
+		storedName := "@each@" + fileID + strings.ToLower(filepath.Ext(incoming.Name()))
 		objectKey := boxObjectKey(box.ID, storedName)
-		contentType := header.Header.Get("Content-Type")
+		contentType := incoming.ContentType()
 		if contentType == "" {
 			buffer := make([]byte, 512)
 			n, _ := file.Read(buffer)
@@ -324,17 +406,18 @@ func (s *UploadService) writeFilesToBox(box *Box, files []*multipart.FileHeader,
 			}
 		}
 
-		if err := s.writeUploadedObject(context.Background(), backend, objectKey, file, header.Size, maxSize, contentType); err != nil {
+		if err := s.writeUploadedObject(ctx, backend, objectKey, file, incoming.Size(), maxSize, contentType); err != nil {
 			file.Close()
+			_ = backend.Delete(context.Background(), objectKey)
 			return err
 		}
 		file.Close()
 
 		box.Files = append(box.Files, File{
 			ID:          fileID,
-			Name:        filepath.Base(header.Filename),
+			Name:        filepath.Base(incoming.Name()),
 			StoredName:  storedName,
-			Size:        header.Size,
+			Size:        incoming.Size(),
 			ContentType: contentType,
 			PreviewKind: previewKind(contentType),
 			ObjectKey:   objectKey,
@@ -736,6 +819,9 @@ func (s *UploadService) ThumbnailObjectKey(box Box, file File) string {
 }
 
 func (s *UploadService) OpenFileObject(ctx context.Context, box Box, file File) (StorageObject, error) {
+	if file.Processing {
+		return StorageObject{}, fmt.Errorf("file is still processing")
+	}
 	backend, err := s.storage.Backend(s.BoxStorageBackendID(box))
 	if err != nil {
 		return StorageObject{}, err
@@ -857,6 +943,13 @@ func (s *UploadService) WriteZip(w io.Writer, box Box) error {
 }
 
 func (s *UploadService) SaveBox(box Box) error {
+	if err := s.saveBoxRecord(box); err != nil {
+		return err
+	}
+	return s.writeBoxMetadata(box)
+}
+
+func (s *UploadService) saveBoxRecord(box Box) error {
 	if box.StorageBackendID == "" {
 		box.StorageBackendID = StorageBackendLocal
 	}
@@ -866,10 +959,7 @@ func (s *UploadService) SaveBox(box Box) error {
 	}
 
 	return s.db.Update(func(tx *bbolt.Tx) error {
-		if err := tx.Bucket(boxesBucket).Put([]byte(box.ID), data); err != nil {
-			return err
-		}
-		return s.writeBoxMetadata(box)
+		return tx.Bucket(boxesBucket).Put([]byte(box.ID), data)
 	})
 }
 
@@ -882,6 +972,7 @@ func (s *UploadService) resultForBox(box Box, deleteToken string) UploadResult {
 			Size:         helpers.FormatBytes(file.Size),
 			URL:          fmt.Sprintf("%s/d/%s/f/%s", s.baseURL, box.ID, file.ID),
 			ThumbnailURL: fmt.Sprintf("%s/d/%s/thumb/%s", s.baseURL, box.ID, file.ID),
+			Processing:   file.Processing,
 		})
 	}
 
@@ -931,21 +1022,34 @@ func writeUploadedFile(path string, source multipart.File, maxSize int64) error
 	return nil
 }
 
-func (s *UploadService) writeUploadedObject(ctx context.Context, backend StorageBackend, key string, source multipart.File, size, maxSize int64, contentType string) error {
+func (s *UploadService) writeUploadedObject(ctx context.Context, backend StorageBackend, key string, source io.Reader, size, maxSize int64, contentType string) error {
 	var reader io.Reader = source
+	putSize := size
 	if maxSize > 0 {
-		reader = io.LimitReader(source, maxSize+1)
-		var buffer bytes.Buffer
-		written, err := io.Copy(&buffer, reader)
-		if err != nil {
-			return err
-		}
-		if written > maxSize {
+		if size > maxSize {
 			return fmt.Errorf("file exceeds max upload size")
 		}
-		return backend.Put(ctx, key, bytes.NewReader(buffer.Bytes()), written, contentType)
+		reader = io.LimitReader(source, maxSize)
+		putSize = size
+	}
+	if ctx != nil {
+		reader = contextReader{ctx: ctx, reader: reader}
+	}
+	return backend.Put(ctx, key, reader, putSize, contentType)
+}
+
+type contextReader struct {
+	ctx    context.Context
+	reader io.Reader
+}
+
+func (r contextReader) Read(p []byte) (int, error) {
+	select {
+	case <-r.ctx.Done():
+		return 0, r.ctx.Err()
+	default:
+		return r.reader.Read(p)
 	}
-	return backend.Put(ctx, key, reader, size, contentType)
 }
 
 func boxObjectKey(boxID, name string) string {

backend/libs/services/upload_test.go

@@ -126,6 +126,262 @@ func TestLocalStorageBackendAndLegacyFallback(t *testing.T) {
 	object.Body.Close()
 }
 
+func TestResumableSessionUploadOutOfOrderAndComplete(t *testing.T) {
+	service := newTestUploadService(t)
+	session, err := service.CreateResumableSession([]ResumableFileInput{{
+		Name:        "note.txt",
+		Size:        11,
+		ContentType: "text/plain",
+		Fingerprint: "sha256:first-chunk",
+	}}, UploadOptions{MaxDays: 1, Password: "secret"}, 4, time.Hour, "")
+	if err != nil {
+		t.Fatalf("CreateResumableSession returned error: %v", err)
+	}
+	if session.ResumeToken == "" || session.ResumeTokenHash == "" {
+		t.Fatalf("resumable session did not create resume token: %+v", session)
+	}
+	if !service.VerifyResumableToken(session, session.ResumeToken) {
+		t.Fatalf("VerifyResumableToken rejected correct token")
+	}
+	if service.VerifyResumableToken(session, "wrong-token") {
+		t.Fatalf("VerifyResumableToken accepted wrong token")
+	}
+	stored, err := service.GetResumableSession(session.ID)
+	if err != nil {
+		t.Fatalf("GetResumableSession returned error: %v", err)
+	}
+	if stored.ResumeToken != "" {
+		t.Fatalf("stored session leaked raw resume token")
+	}
+	if strings.Contains(stored.ResumeTokenHash, session.ResumeToken) {
+		t.Fatalf("stored token hash contains raw token")
+	}
+	if !service.VerifyResumableToken(stored, session.ResumeToken) {
+		t.Fatalf("stored session rejected correct token")
+	}
+	if session.Options.Password != "" || session.Options.PasswordHash == "" || session.Options.PasswordSalt == "" {
+		t.Fatalf("resumable session did not hash password before storage: %+v", session.Options)
+	}
+	if session.Files[0].ChunkCount != 3 {
+		t.Fatalf("ChunkCount = %d, want 3", session.Files[0].ChunkCount)
+	}
+	if session.Files[0].Fingerprint != "sha256:first-chunk" {
+		t.Fatalf("Fingerprint = %q", session.Files[0].Fingerprint)
+	}
+	for index, body := range map[int]string{2: "rld", 0: "hell", 1: "o wo"} {
+		updated, err := service.PutResumableChunk(testContext(), session.ID, session.Files[0].ID, index, strings.NewReader(body))
+		if err != nil {
+			t.Fatalf("PutResumableChunk(%d) returned error: %v", index, err)
+		}
+		if len(updated.Files[0].UploadedChunks) == 0 {
+			t.Fatalf("UploadedChunks was not updated")
+		}
+	}
+	result, completed, err := service.CompleteResumableSession(testContext(), session.ID)
+	if err != nil {
+		t.Fatalf("CompleteResumableSession returned error: %v", err)
+	}
+	if completed.Status != ResumableStatusCompleted || completed.BoxID != result.BoxID {
+		t.Fatalf("completed session = %+v, result = %+v", completed, result)
+	}
+	box := getTestBox(t, service, result.BoxID)
+	if box.PasswordHash == "" || box.PasswordSalt == "" || box.PasswordHash != session.Options.PasswordHash {
+		t.Fatalf("completed box did not preserve hashed password")
+	}
+	object, err := service.OpenFileObject(testContext(), box, box.Files[0])
+	if err != nil {
+		t.Fatalf("OpenFileObject returned error: %v", err)
+	}
+	data, err := io.ReadAll(object.Body)
+	object.Body.Close()
+	if err != nil {
+		t.Fatalf("ReadAll returned error: %v", err)
+	}
+	if string(data) != "hello world" {
+		t.Fatalf("object body = %q", string(data))
+	}
+	if _, err := os.Stat(service.resumableSessionDir(session.ID)); !os.IsNotExist(err) {
+		t.Fatalf("resumable temp dir after complete error = %v, want os.ErrNotExist", err)
+	}
+	replayed, replayedSession, err := service.CompleteResumableSession(testContext(), session.ID)
+	if err != nil {
+		t.Fatalf("CompleteResumableSession replay returned error: %v", err)
+	}
+	if replayed.BoxID != result.BoxID || replayedSession.Status != ResumableStatusCompleted {
+		t.Fatalf("replayed result = %+v, session = %+v, want box %s completed", replayed, replayedSession, result.BoxID)
+	}
+}
+
+func TestResumableCompleteRejectsMissingChunks(t *testing.T) {
+	service := newTestUploadService(t)
+	session, err := service.CreateResumableSession([]ResumableFileInput{{
+		Name:        "note.txt",
+		Size:        8,
+		ContentType: "text/plain",
+	}}, UploadOptions{MaxDays: 1}, 4, time.Hour, "")
+	if err != nil {
+		t.Fatalf("CreateResumableSession returned error: %v", err)
+	}
+	if _, err := service.PutResumableChunk(testContext(), session.ID, session.Files[0].ID, 0, strings.NewReader("hell")); err != nil {
+		t.Fatalf("PutResumableChunk returned error: %v", err)
+	}
+	if _, _, err := service.CompleteResumableSession(testContext(), session.ID); err == nil {
+		t.Fatalf("CompleteResumableSession accepted missing chunks")
+	}
+}
+
+func TestResumablePartialCompleteKeepsOnlyFinishedFiles(t *testing.T) {
+	service := newTestUploadService(t)
+	session, err := service.CreateResumableSession([]ResumableFileInput{
+		{Name: "done.txt", Size: 4, ContentType: "text/plain", Fingerprint: "done"},
+		{Name: "partial.txt", Size: 8, ContentType: "text/plain", Fingerprint: "partial"},
+	}, UploadOptions{MaxDays: 1}, 4, time.Hour, "")
+	if err != nil {
+		t.Fatalf("CreateResumableSession returned error: %v", err)
+	}
+	if _, err := service.PutResumableChunk(testContext(), session.ID, session.Files[0].ID, 0, strings.NewReader("done")); err != nil {
+		t.Fatalf("PutResumableChunk done returned error: %v", err)
+	}
+	if _, err := service.PutResumableChunk(testContext(), session.ID, session.Files[1].ID, 0, strings.NewReader("part")); err != nil {
+		t.Fatalf("PutResumableChunk partial returned error: %v", err)
+	}
+	result, completed, err := service.CompleteUploadedResumableSession(testContext(), session.ID)
+	if err != nil {
+		t.Fatalf("CompleteUploadedResumableSession returned error: %v", err)
+	}
+	if completed.Status != ResumableStatusCompleted || completed.BoxID != result.BoxID || len(completed.Files) != 1 {
+		t.Fatalf("completed session = %+v, result = %+v", completed, result)
+	}
+	box := getTestBox(t, service, result.BoxID)
+	if len(box.Files) != 1 || box.Files[0].Name != "done.txt" {
+		t.Fatalf("partial completion box files = %+v", box.Files)
+	}
+	object, err := service.OpenFileObject(testContext(), box, box.Files[0])
+	if err != nil {
+		t.Fatalf("OpenFileObject returned error: %v", err)
+	}
+	data, err := io.ReadAll(object.Body)
+	object.Body.Close()
+	if err != nil {
+		t.Fatalf("ReadAll returned error: %v", err)
+	}
+	if string(data) != "done" {
+		t.Fatalf("partial completion object = %q", string(data))
+	}
+	if _, err := service.GetResumableSession(session.ID); !os.IsNotExist(err) {
+		t.Fatalf("GetResumableSession after partial complete error = %v, want os.ErrNotExist", err)
+	}
+	if _, err := os.Stat(service.resumableSessionDir(session.ID)); !os.IsNotExist(err) {
+		t.Fatalf("resumable temp dir after partial complete error = %v, want os.ErrNotExist", err)
+	}
+}
+
+func TestResumablePartialCompleteRejectsNoFinishedFiles(t *testing.T) {
+	service := newTestUploadService(t)
+	session, err := service.CreateResumableSession([]ResumableFileInput{{
+		Name:        "partial.txt",
+		Size:        8,
+		ContentType: "text/plain",
+	}}, UploadOptions{MaxDays: 1}, 4, time.Hour, "")
+	if err != nil {
+		t.Fatalf("CreateResumableSession returned error: %v", err)
+	}
+	if _, err := service.PutResumableChunk(testContext(), session.ID, session.Files[0].ID, 0, strings.NewReader("part")); err != nil {
+		t.Fatalf("PutResumableChunk returned error: %v", err)
+	}
+	if _, _, err := service.CompleteUploadedResumableSession(testContext(), session.ID); err == nil {
+		t.Fatalf("CompleteUploadedResumableSession accepted no completed files")
+	}
+	if _, err := service.GetResumableSession(session.ID); err != nil {
+		t.Fatalf("GetResumableSession after failed partial complete returned error: %v", err)
+	}
+}
+
+func TestResumableSessionCanAddFilesBeforeComplete(t *testing.T) {
+	service := newTestUploadService(t)
+	session, err := service.CreateResumableSession([]ResumableFileInput{{
+		Name:        "one.txt",
+		Size:        4,
+		ContentType: "text/plain",
+		Fingerprint: "one",
+	}}, UploadOptions{MaxDays: 1}, 4, time.Hour, "")
+	if err != nil {
+		t.Fatalf("CreateResumableSession returned error: %v", err)
+	}
+	if _, err := service.PutResumableChunk(testContext(), session.ID, session.Files[0].ID, 0, strings.NewReader("one!")); err != nil {
+		t.Fatalf("PutResumableChunk one returned error: %v", err)
+	}
+	updated, err := service.AddResumableFiles(session.ID, []ResumableFileInput{{
+		Name:        "two.txt",
+		Size:        4,
+		ContentType: "text/plain",
+		Fingerprint: "two",
+	}})
+	if err != nil {
+		t.Fatalf("AddResumableFiles returned error: %v", err)
+	}
+	if len(updated.Files) != 2 {
+		t.Fatalf("files after add = %d, want 2", len(updated.Files))
+	}
+	if updated.Files[0].UploadedChunks[0] != 0 {
+		t.Fatalf("existing uploaded chunk was not preserved: %+v", updated.Files[0])
+	}
+	if _, err := service.AddResumableFiles(session.ID, []ResumableFileInput{{
+		Name:        "two.txt",
+		Size:        4,
+		ContentType: "text/plain",
+		Fingerprint: "two",
+	}}); err != nil {
+		t.Fatalf("duplicate AddResumableFiles returned error: %v", err)
+	}
+	updated, err = service.GetResumableSession(session.ID)
+	if err != nil {
+		t.Fatalf("GetResumableSession returned error: %v", err)
+	}
+	if len(updated.Files) != 2 {
+		t.Fatalf("duplicate add changed file count to %d", len(updated.Files))
+	}
+	if _, err := service.PutResumableChunk(testContext(), session.ID, updated.Files[1].ID, 0, strings.NewReader("two!")); err != nil {
+		t.Fatalf("PutResumableChunk two returned error: %v", err)
+	}
+	result, _, err := service.CompleteResumableSession(testContext(), session.ID)
+	if err != nil {
+		t.Fatalf("CompleteResumableSession returned error: %v", err)
+	}
+	box := getTestBox(t, service, result.BoxID)
+	if len(box.Files) != 2 {
+		t.Fatalf("completed box file count = %d, want 2", len(box.Files))
+	}
+}
+
+func TestResumableCleanupRemovesExpiredSessionsAndChunks(t *testing.T) {
+	service := newTestUploadService(t)
+	session, err := service.CreateResumableSession([]ResumableFileInput{{
+		Name:        "note.txt",
+		Size:        4,
+		ContentType: "text/plain",
+	}}, UploadOptions{MaxDays: 1}, 4, time.Millisecond, "")
+	if err != nil {
+		t.Fatalf("CreateResumableSession returned error: %v", err)
+	}
+	if _, err := service.PutResumableChunk(testContext(), session.ID, session.Files[0].ID, 0, strings.NewReader("hell")); err != nil {
+		t.Fatalf("PutResumableChunk returned error: %v", err)
+	}
+	cleaned, err := service.CleanupExpiredResumableSessions(time.Now().UTC().Add(time.Hour))
+	if err != nil {
+		t.Fatalf("CleanupExpiredResumableSessions returned error: %v", err)
+	}
+	if cleaned != 1 {
+		t.Fatalf("cleaned = %d, want 1", cleaned)
+	}
+	if _, err := service.GetResumableSession(session.ID); !os.IsNotExist(err) {
+		t.Fatalf("GetResumableSession after cleanup error = %v, want os.ErrNotExist", err)
+	}
+	if _, err := os.Stat(service.resumableSessionDir(session.ID)); !os.IsNotExist(err) {
+		t.Fatalf("resumable temp dir after cleanup error = %v, want os.ErrNotExist", err)
+	}
+}
+
 func TestContaboStorageConfigAllowsDisplayNamesWithSpaces(t *testing.T) {
 	service := newTestUploadService(t)
 	cfg, err := service.Storage().CreateS3Backend(StorageBackendConfig{

backend/static/css/20-upload.css

@@ -48,6 +48,10 @@
   width: 100%;
 }
 
+.upload-options .form-footer .upload-new-button {
+  margin-top: -0.25rem;
+}
+
 .hero-copy {
   text-align: center;
 }
@@ -335,10 +339,13 @@ button {
 .file-progress-side {
   width: min(10rem, 32vw);
   display: grid;
+  grid-template-columns: minmax(0, 1fr) auto;
   gap: 0.35rem;
+  align-items: center;
 }
 
 .file-progress-percent {
+  grid-column: 1 / -1;
   color: var(--muted-foreground);
   font-size: 0.75rem;
   text-align: right;
@@ -349,6 +356,81 @@ button {
   margin-top: 0;
 }
 
+.upload-file-remove {
+  width: 1.65rem;
+  height: 1.65rem;
+  min-height: 1.65rem;
+  padding: 0;
+  border-color: var(--border);
+  border-radius: 999px;
+  color: var(--muted-foreground);
+  background: var(--surface-1);
+  font-size: 1rem;
+  line-height: 1;
+}
+
+.upload-file-remove:hover {
+  color: var(--foreground);
+  border-color: var(--primary);
+  background: var(--surface-1-hover);
+}
+
+.upload-file-waiting {
+  border-color: color-mix(in srgb, var(--primary) 42%, var(--border));
+  background: color-mix(in srgb, var(--primary) 8%, var(--background));
+}
+
+.upload-file-complete .file-progress span {
+  background: var(--success);
+}
+
+.upload-file-state {
+  grid-column: 1 / -1;
+  color: var(--muted-foreground);
+  font-size: 0.72rem;
+  text-align: right;
+}
+
+.upload-recovery-overlay {
+  position: fixed;
+  inset: 0;
+  z-index: 80;
+  display: grid;
+  place-items: center;
+  padding: 1rem;
+  background: color-mix(in srgb, var(--background) 72%, transparent);
+  backdrop-filter: blur(10px);
+}
+
+.upload-recovery-modal {
+  width: min(34rem, 100%);
+  box-shadow: var(--shadow-lg);
+}
+
+.upload-recovery-modal h2 {
+  margin: 0 0 0.65rem;
+  font-size: 1.35rem;
+}
+
+.upload-recovery-modal p {
+  margin: 0;
+  color: var(--muted-foreground);
+  line-height: 1.55;
+}
+
+.upload-recovery-actions {
+  display: grid;
+  grid-template-columns: repeat(2, minmax(0, 1fr));
+  gap: 0.7rem;
+  margin-top: 1.25rem;
+}
+
+@media (max-width: 640px) {
+  .upload-recovery-actions {
+    grid-template-columns: 1fr;
+  }
+}
+
 .result-item small,
 .download-item small,
 .result-item code,

backend/static/css/30-download.css

@@ -46,6 +46,15 @@
   text-decoration: none;
 }
 
+.upload-processing-alert {
+  margin: 1rem 0;
+  padding: .85rem 1rem;
+  border: 1px solid color-mix(in srgb, var(--primary) 45%, transparent);
+  border-radius: var(--radius);
+  background: color-mix(in srgb, var(--primary) 12%, transparent);
+  color: var(--foreground);
+}
+
 .thumb-link {
   flex: 0 0 4.75rem;
   width: 4.75rem;
@@ -200,6 +209,15 @@
   padding: 0;
 }
 
+.file-card.is-processing {
+  opacity: .62;
+  filter: grayscale(.25);
+}
+
+.file-card.is-processing .file-open {
+  cursor: wait;
+}
+
 .file-reaction-dock {
   position: static;
   z-index: 2;

backend/static/js/00-utils.js

@@ -5,6 +5,17 @@
     window.open(url, "_blank", "noopener,noreferrer");
   };
 
+  window.Warpbox.absoluteURL = function absoluteURL(url) {
+    if (!url) {
+      return "";
+    }
+    try {
+      return new URL(url, window.location.origin).href;
+    } catch (_) {
+      return url;
+    }
+  };
+
   window.Warpbox.writeClipboard = async function writeClipboard(text) {
     if (navigator.clipboard && window.isSecureContext) {
       await navigator.clipboard.writeText(text);
@@ -26,6 +37,9 @@
     if (!text || !button) {
       return;
     }
+    if (typeof text === "string" && (text.startsWith("/") || /^https?:\/\//i.test(text))) {
+      text = window.Warpbox.absoluteURL(text);
+    }
     await window.Warpbox.writeClipboard(text);
     const previous = button.textContent;
     button.textContent = copiedLabel;

backend/static/js/10-file-browser.js

@@ -124,7 +124,7 @@
   }
 
   async function copyPreviewLink(button) {
-    await window.Warpbox.writeClipboard(button.href);
+    await window.Warpbox.writeClipboard(window.Warpbox.absoluteURL(button.href));
     const label = button.querySelector("[data-preview-label]");
     if (!label) {
       return;
@@ -164,11 +164,11 @@
       return true;
     }
     if (action === "copy-preview") {
-      await window.Warpbox.writeClipboard(file.previewURL);
+      await window.Warpbox.writeClipboard(window.Warpbox.absoluteURL(file.previewURL));
       return true;
     }
     if (action === "copy-download") {
-      await window.Warpbox.writeClipboard(file.downloadURL);
+      await window.Warpbox.writeClipboard(window.Warpbox.absoluteURL(file.downloadURL));
       return true;
     }
     if (action === "download") {

backend/static/js/40-upload.js

@@ -13,6 +13,8 @@
   const copyURL = document.querySelector("#copy-url");
   const openBox = document.querySelector("#open-box");
   const manageLink = document.querySelector("#manage-link");
+  const newUpload = document.querySelector("#new-upload");
+  const RESUMABLE_SESSIONS_KEY = "warpbox-resumable-sessions";
 
   if (!form || !dropZone || !fileInput) {
     return;
@@ -42,6 +44,9 @@
 
   let latestBoxURL = "";
   let selectedFiles = [];
+  let uploadLocked = false;
+  let recoveredDraft = null;
+  let resumeMode = false;
 
   ["dragenter", "dragover"].forEach((eventName) => {
     dropZone.addEventListener(eventName, (event) => {
@@ -57,33 +62,67 @@
     });
   });
 
-  dropZone.addEventListener("drop", (event) => {
-    if (event.dataTransfer && event.dataTransfer.files.length > 0) {
-      fileInput.files = event.dataTransfer.files;
-      updateSelectedState(event.dataTransfer.files);
+  document.addEventListener("dragover", (event) => {
+    if (event.dataTransfer && Array.from(event.dataTransfer.types || []).includes("Files")) {
+      event.preventDefault();
     }
   });
 
-  fileInput.addEventListener("change", () => updateSelectedState(fileInput.files));
+  document.addEventListener("drop", (event) => {
+    if (!event.dataTransfer || !event.dataTransfer.files.length) {
+      return;
+    }
+    event.preventDefault();
+    if (!dropZone.contains(event.target)) {
+      addSelectedFiles(event.dataTransfer.files);
+    }
+  });
+
+  dropZone.addEventListener("drop", (event) => {
+    if (event.dataTransfer && event.dataTransfer.files.length > 0) {
+      addSelectedFiles(event.dataTransfer.files);
+    }
+  });
+
+  fileInput.addEventListener("change", () => {
+    addSelectedFiles(fileInput.files);
+    fileInput.value = "";
+  });
 
   form.addEventListener("submit", async (event) => {
     event.preventDefault();
-    if (!fileInput.files || fileInput.files.length === 0) {
+    if (selectedFiles.length === 0) {
       updateStatus("Choose at least one file first.");
       return;
     }
 
     const submit = form.querySelector("button[type='submit']");
-    const formData = new FormData(form);
-    selectedFiles = Array.from(fileInput.files);
-    renderQueue(selectedFiles, "queued");
+    const formData = uploadFormData();
+    if (resumeMode && recoveredDraft) {
+      renderResumeQueue(recoveredDraft.session, selectedFiles);
+    } else {
+      renderQueue(selectedFiles, "queued");
+    }
     setLoading(true, submit);
 
     try {
-      const payload = await uploadWithProgress(form.action, formData, selectedFiles);
+      const payload = await uploadResumable(form.action, formData, selectedFiles);
       renderResult(payload);
       form.reset();
-      updateSelectedState([]);
+      selectedFiles = [];
+      resumeMode = false;
+      recoveredDraft = null;
+      fileInput.value = "";
+      if (uploadQueue) {
+        uploadQueue.hidden = true;
+        uploadQueue.replaceChildren();
+      }
+      if (newUpload) {
+        newUpload.hidden = true;
+      }
+      if (fileSummary) {
+        fileSummary.textContent = "Upload complete.";
+      }
     } catch (error) {
       updateStatus(error.message || "Upload failed");
     } finally {
@@ -97,25 +136,66 @@
     });
   }
 
-  function updateSelectedState(files) {
-    selectedFiles = Array.from(files || []);
+  if (newUpload) {
+    newUpload.addEventListener("click", () => {
+      cancelRecoveredDraft().catch((error) => {
+        updateStatus(error.message || "Upload draft could not be deleted");
+      });
+    });
+  }
+
+  recoverResumableSessions();
+
+  function addSelectedFiles(files) {
+    if (uploadLocked) {
+      return;
+    }
+    Array.from(files || []).forEach((file) => {
+      if (!selectedFiles.some((existing) => fileIdentity(existing) === fileIdentity(file))) {
+        selectedFiles.push(file);
+      }
+    });
+    updateSelectedState();
+  }
+
+  function removeSelectedFile(index) {
+    if (uploadLocked) {
+      return;
+    }
+    selectedFiles.splice(index, 1);
+    updateSelectedState();
+  }
+
+  function updateSelectedState() {
     const count = selectedFiles.length || 0;
     const title = dropZone.querySelector(".drop-title");
     if (title) {
       title.textContent = count === 0 ? "Drop files to upload" : count === 1 ? "1 file selected" : `${count} files selected`;
     }
     if (fileSummary) {
-      fileSummary.textContent = count === 0 ? "Choose one or more files to begin." : `${count} file${count === 1 ? "" : "s"} ready.`;
+      if (resumeMode && recoveredDraft) {
+        fileSummary.textContent = count === 0
+          ? "Reselect missing files to resume, or add extra files to this upload."
+          : `${count} local file${count === 1 ? "" : "s"} ready for the recovered upload.`;
+      } else {
+        fileSummary.textContent = count === 0 ? "Choose one or more files to begin." : `${count} file${count === 1 ? "" : "s"} ready.`;
+      }
     }
-    if (count > 0) {
+    if (resumeMode && recoveredDraft) {
+      renderResumeQueue(recoveredDraft.session, selectedFiles);
+    } else if (count > 0) {
       renderQueue(selectedFiles, "queued");
     } else if (uploadQueue) {
       uploadQueue.hidden = true;
       uploadQueue.replaceChildren();
     }
+    if (newUpload) {
+      newUpload.hidden = !(resumeMode && recoveredDraft);
+    }
   }
 
   function setLoading(isLoading, submit) {
+    uploadLocked = isLoading;
     if (progress) {
       progress.hidden = !isLoading;
     }
@@ -123,6 +203,9 @@
       submit.disabled = isLoading;
       submit.textContent = isLoading ? "Uploading..." : "Upload files";
     }
+    if (newUpload) {
+      newUpload.disabled = isLoading;
+    }
     updateStatus(isLoading ? "Transferring files..." : "");
     setTotalProgress(isLoading ? 0 : 100);
   }
@@ -138,15 +221,15 @@
       return;
     }
 
-    latestBoxURL = payload.boxUrl;
+    latestBoxURL = window.Warpbox.absoluteURL(payload.boxUrl);
     result.hidden = false;
-    openBox.href = payload.boxUrl;
+    openBox.href = latestBoxURL;
     resultMeta.textContent = `${payload.files.length} file${payload.files.length === 1 ? "" : "s"} · expires ${window.Warpbox.formatDate(payload.expiresAt)}`;
     if (manageLink) {
       const anchor = manageLink.querySelector("a");
       manageLink.hidden = !payload.manageUrl;
       if (anchor && payload.manageUrl) {
-        anchor.href = payload.manageUrl;
+        anchor.href = window.Warpbox.absoluteURL(payload.manageUrl);
       }
     }
 
@@ -154,11 +237,12 @@
     payload.files.forEach((file) => {
       resultList.append(createFileRow({
         name: file.name,
-        meta: `${file.size} · ${file.url}`,
+        meta: `${file.size} · ${window.Warpbox.absoluteURL(file.url)}`,
         progress: 100,
         status: "complete",
       }));
     });
+    result.scrollIntoView({ behavior: "smooth", block: "start" });
   }
 
   function uploadWithProgress(url, formData, files) {
@@ -201,26 +285,612 @@
     });
   }
 
+  async function uploadResumable(fallbackUrl, formData, files) {
+    if (!window.fetch || typeof Blob === "undefined") {
+      return uploadWithProgress(fallbackUrl, formData, files);
+    }
+
+    updateStatus("Fingerprinting files...");
+    const fingerprints = await Promise.all(files.map((file) => fileFingerprint(file)));
+    const createPayload = {
+      files: files.map((file, index) => ({
+        name: file.name,
+        size: file.size,
+        contentType: file.type || "application/octet-stream",
+        fingerprint: fingerprints[index],
+      })),
+      expiresMinutes: parseInt(formData.get("expires_minutes") || "0", 10) || 0,
+      maxDownloads: parseInt(formData.get("max_downloads") || "0", 10) || 0,
+      password: formData.get("password") || "",
+      obfuscateMetadata: formData.get("obfuscate_metadata") === "on",
+      collectionId: formData.get("collection_id") || "",
+    };
+    const persistable = !createPayload.password;
+    let session = null;
+    if (persistable && resumeMode && recoveredDraft) {
+      session = await fetchResumableStatus(recoveredDraft.session.sessionId, recoveredDraft.session.resumeToken);
+      session.resumeToken = recoveredDraft.session.resumeToken;
+    } else if (persistable) {
+      session = await findResumableSession(createPayload);
+    }
+    if (session) {
+      validateResumeSelection(session, createPayload);
+      session = await addMissingResumableFiles(session, createPayload);
+      if (resumeMode && recoveredDraft && recoveredDraft.session.sessionId === session.sessionId) {
+        recoveredDraft.session = session;
+      }
+      if (persistable) {
+        saveResumableSession(session, createPayload);
+      }
+    }
+    if (!session || session.status !== "uploading") {
+      try {
+        session = await createResumableSession(createPayload);
+      } catch (error) {
+        if ((error.message || "").toLowerCase().includes("resumable uploads are disabled")) {
+          return uploadWithProgress(fallbackUrl, formData, files);
+        }
+        throw error;
+      }
+      if (persistable) {
+        saveResumableSession(session, createPayload);
+      }
+    }
+    const sessionFiles = files.map((file, index) => matchSessionFile(session, createPayload.files[index]));
+    if (sessionFiles.some((file) => !file)) {
+      throw new Error("Upload session could not match the selected files");
+    }
+
+    updateStatus("Uploading...");
+    const totalBytes = files.reduce((sum, file) => sum + file.size, 0);
+    const completedByFile = new Array(files.length).fill(0);
+    sessionFiles.forEach((sessionFile, index) => {
+      completedByFile[index] = uploadedBytesForSessionFile(sessionFile, session.chunkSize);
+      setSingleFileProgress(index, files[index], percentForBytes(completedByFile[index], files[index].size));
+    });
+    setTotalProgress(percentForBytes(completedByFile.reduce((sum, bytes) => sum + bytes, 0), totalBytes));
+
+    for (let fileIndex = 0; fileIndex < files.length; fileIndex++) {
+      const file = files[fileIndex];
+      const sessionFile = sessionFiles[fileIndex];
+      const uploaded = new Set(sessionFile.uploadedChunks || []);
+      for (let chunkIndex = 0; chunkIndex < sessionFile.chunkCount; chunkIndex++) {
+        if (uploaded.has(chunkIndex)) {
+          continue;
+        }
+        const start = chunkIndex * session.chunkSize;
+        const end = Math.min(file.size, start + session.chunkSize);
+        await uploadChunkWithRetry(session, sessionFile, chunkIndex, file.slice(start, end), (loaded) => {
+          const currentTotal = completedByFile.reduce((sum, bytes) => sum + bytes, 0) + loaded;
+          setTotalProgress(percentForBytes(currentTotal, totalBytes));
+          setSingleFileProgress(fileIndex, file, percentForBytes(completedByFile[fileIndex] + loaded, file.size));
+          updateStatus(`${percentForBytes(currentTotal, totalBytes)}%`);
+        });
+        completedByFile[fileIndex] += end - start;
+        uploaded.add(chunkIndex);
+        sessionFile.uploadedChunks = Array.from(uploaded).sort((a, b) => a - b);
+        if (persistable) {
+          saveResumableSession(session, createPayload);
+        }
+      }
+      setSingleFileProgress(fileIndex, file, 100);
+    }
+
+    updateStatus("Finalizing upload...");
+    const resultPayload = await completeResumableSession(session.sessionId, session.resumeToken);
+    const wasResumeMode = resumeMode;
+    if (persistable) {
+      removeResumableSession(session.sessionId);
+    }
+    if (resumeMode && recoveredDraft && recoveredDraft.session.sessionId === session.sessionId) {
+      resumeMode = false;
+      recoveredDraft = null;
+    }
+    setTotalProgress(100);
+    if (!wasResumeMode) {
+      setFileProgress(files, 100);
+    }
+    return resultPayload;
+  }
+
+  async function createResumableSession(payload) {
+    const response = await fetch("/api/v1/uploads/resumable", {
+      method: "POST",
+      headers: {
+        "Accept": "application/json",
+        "Content-Type": "application/json",
+      },
+      body: JSON.stringify(payload),
+    });
+    return readUploadJSON(response, "Upload session could not be created");
+  }
+
+  async function fetchResumableStatus(sessionID, resumeToken) {
+    const response = await fetch(`/api/v1/uploads/resumable/${encodeURIComponent(sessionID)}`, {
+      headers: resumableHeaders(resumeToken),
+    });
+    return readUploadJSON(response, "Upload session could not be resumed");
+  }
+
+  async function addResumableFiles(sessionID, resumeToken, files) {
+    const response = await fetch(`/api/v1/uploads/resumable/${encodeURIComponent(sessionID)}/files`, {
+      method: "POST",
+      headers: {
+        ...resumableHeaders(resumeToken),
+        "Accept": "application/json",
+        "Content-Type": "application/json",
+      },
+      body: JSON.stringify({ files }),
+    });
+    return readUploadJSON(response, "Upload session files could not be added");
+  }
+
+  function uploadChunk(sessionID, resumeToken, fileID, chunkIndex, chunk, onProgress) {
+    return new Promise((resolve, reject) => {
+      const request = new XMLHttpRequest();
+      request.open("PUT", `/api/v1/uploads/resumable/${encodeURIComponent(sessionID)}/files/${encodeURIComponent(fileID)}/chunks/${chunkIndex}`);
+      request.setRequestHeader("Accept", "application/json");
+      request.setRequestHeader("X-Warpbox-Resume-Token", resumeToken || "");
+      request.upload.addEventListener("progress", (event) => {
+        if (event.lengthComputable && onProgress) {
+          onProgress(event.loaded);
+        }
+      });
+      request.addEventListener("load", () => {
+        if (request.status < 200 || request.status >= 300) {
+          let payload = {};
+          try {
+            payload = JSON.parse(request.responseText || "{}");
+          } catch (error) {
+            payload = {};
+          }
+          reject(new Error(payload.error || "Chunk upload failed"));
+          return;
+        }
+        resolve();
+      });
+      request.addEventListener("error", () => reject(new Error("Network error during chunk upload")));
+      request.addEventListener("abort", () => reject(new Error("Chunk upload aborted")));
+      request.send(chunk);
+    });
+  }
+
+  async function uploadChunkWithRetry(session, sessionFile, chunkIndex, chunk, onProgress) {
+    const delays = [1000, 2000, 5000, 10000, 20000];
+    let lastError = null;
+    for (let attempt = 0; attempt <= delays.length; attempt++) {
+      try {
+        return await uploadChunk(session.sessionId, session.resumeToken, sessionFile.id, chunkIndex, chunk, onProgress);
+      } catch (error) {
+        lastError = error;
+        if (attempt >= delays.length) {
+          break;
+        }
+        const seconds = Math.round(delays[attempt] / 1000);
+        updateStatus(`Connection interrupted, retrying chunk ${chunkIndex + 1} in ${seconds}s`);
+        await wait(delays[attempt]);
+      }
+    }
+    throw lastError || new Error("Chunk upload failed");
+  }
+
+  async function completeResumableSession(sessionID, resumeToken) {
+    const response = await fetch(`/api/v1/uploads/resumable/${encodeURIComponent(sessionID)}/complete`, {
+      method: "POST",
+      headers: resumableHeaders(resumeToken),
+    });
+    return readUploadJSON(response, "Upload could not be completed");
+  }
+
+  async function cancelResumableSession(sessionID, resumeToken) {
+    const response = await fetch(`/api/v1/uploads/resumable/${encodeURIComponent(sessionID)}`, {
+      method: "DELETE",
+      headers: resumableHeaders(resumeToken),
+    });
+    if (!response.ok && response.status !== 404) {
+      await readUploadJSON(response, "Upload draft could not be deleted");
+    }
+  }
+
+  function resumableHeaders(resumeToken) {
+    return {
+      "Accept": "application/json",
+      "X-Warpbox-Resume-Token": resumeToken || "",
+    };
+  }
+
+  function wait(ms) {
+    return new Promise((resolve) => window.setTimeout(resolve, ms));
+  }
+
+  async function readUploadJSON(response, fallback) {
+    let payload = {};
+    try {
+      payload = await response.json();
+    } catch (error) {
+      payload = {};
+    }
+    if (!response.ok) {
+      throw new Error(payload.error || fallback);
+    }
+    return payload;
+  }
+
+  async function findResumableSession(payload) {
+    const records = loadResumableSessions();
+    const optionKey = resumableOptionKey(payload);
+    const selectedKeys = new Set(payload.files.map((file) => resumableFileKey(file)));
+    for (const record of records) {
+      if (record.optionKey !== optionKey) {
+        continue;
+      }
+      if (!record.files || !record.files.some((file) => selectedKeys.has(resumableFileKey(file)))) {
+        continue;
+      }
+      const session = await fetchResumableStatus(record.sessionId, record.resumeToken).catch(() => null);
+      if (!session || session.status !== "uploading") {
+        removeResumableSession(record.sessionId);
+        continue;
+      }
+      session.resumeToken = record.resumeToken;
+      const sessionKeys = new Set(session.files.map((file) => resumableFileKey(file)));
+      const selectedContainsSessionFile = Array.from(sessionKeys).some((key) => selectedKeys.has(key));
+      if (selectedContainsSessionFile) {
+        return session;
+      }
+    }
+    return null;
+  }
+
+  async function addMissingResumableFiles(session, payload) {
+    const existing = new Set(session.files.map((file) => resumableFileKey(file)));
+    const missing = payload.files.filter((file) => !existing.has(resumableFileKey(file)));
+    if (missing.length === 0) {
+      return session;
+    }
+    const updated = await addResumableFiles(session.sessionId, session.resumeToken, missing);
+    updated.resumeToken = session.resumeToken;
+    return updated;
+  }
+
+  function validateResumeSelection(session, payload) {
+    if (!resumeMode || !recoveredDraft || session.sessionId !== recoveredDraft.session.sessionId) {
+      return;
+    }
+    const existingByNameSize = new Map();
+    (session.files || []).forEach((file) => {
+      existingByNameSize.set(`${file.name}:${file.size}`, resumableFileKey(file));
+    });
+    for (const file of payload.files || []) {
+      const expectedKey = existingByNameSize.get(`${file.name}:${file.size}`);
+      if (expectedKey && expectedKey !== resumableFileKey(file)) {
+        throw new Error(`"${file.name}" does not match the pending upload. Select the exact original file.`);
+      }
+    }
+  }
+
+  function matchSessionFile(session, file) {
+    const key = resumableFileKey(file);
+    return session.files.find((sessionFile) => resumableFileKey(sessionFile) === key) || null;
+  }
+
+  function resumableOptionKey(payload) {
+    return [
+      payload.expiresMinutes,
+      payload.maxDownloads,
+      payload.obfuscateMetadata ? "1" : "0",
+      payload.collectionId || "",
+    ].join(":");
+  }
+
+  function resumableFileKey(file) {
+    return [file.name, file.size, file.fingerprint || ""].join(":");
+  }
+
+  function loadResumableSessions() {
+    try {
+      const value = localStorage.getItem(RESUMABLE_SESSIONS_KEY);
+      const records = value ? JSON.parse(value) : [];
+      return Array.isArray(records) ? records : [];
+    } catch (error) {
+      return [];
+    }
+  }
+
+  function saveResumableSession(session, payload) {
+    try {
+      const records = loadResumableSessions().filter((record) => record.sessionId !== session.sessionId);
+      records.push({
+        sessionId: session.sessionId,
+        resumeToken: session.resumeToken || "",
+        optionKey: resumableOptionKey(payload),
+        options: {
+          expiresMinutes: payload.expiresMinutes,
+          maxDownloads: payload.maxDownloads,
+          obfuscateMetadata: !!payload.obfuscateMetadata,
+          collectionId: payload.collectionId || "",
+        },
+        files: session.files.map((file) => ({
+          name: file.name,
+          size: file.size,
+          contentType: file.contentType || "application/octet-stream",
+          fingerprint: file.fingerprint || "",
+          uploadedChunks: file.uploadedChunks || [],
+          chunkCount: file.chunkCount || 0,
+        })),
+        updatedAt: new Date().toISOString(),
+      });
+      localStorage.setItem(RESUMABLE_SESSIONS_KEY, JSON.stringify(records.slice(-25)));
+    } catch (error) {
+      /* ignore persistence failures */
+    }
+  }
+
+  async function recoverResumableSessions() {
+    const records = loadResumableSessions()
+      .filter((record) => record.sessionId && record.resumeToken)
+      .sort((a, b) => new Date(b.updatedAt || 0).getTime() - new Date(a.updatedAt || 0).getTime());
+    if (records.length === 0) {
+      return;
+    }
+    for (const record of records) {
+      const session = await fetchResumableStatus(record.sessionId, record.resumeToken).catch(() => null);
+      if (!session || session.status !== "uploading") {
+        removeResumableSession(record.sessionId);
+        continue;
+      }
+      session.resumeToken = record.resumeToken;
+      recoveredDraft = { session, record };
+      selectedFiles = [];
+      renderRecoveredQueue([{ session, record }]);
+      updateRecoveredSummary(session);
+      showRecoveryModal(recoveredDraft);
+      return;
+    }
+  }
+
+  function updateRecoveredSummary(session) {
+    updateStatus("Unfinished upload found. Choose how to continue.");
+    if (fileSummary) {
+      const totalFiles = (session.files || []).length;
+      const completedFiles = completedSessionFiles(session).length;
+      fileSummary.textContent = `Recovered ${totalFiles} pending file${totalFiles === 1 ? "" : "s"}; ${completedFiles} fully uploaded.`;
+    }
+  }
+
+  function removeResumableSession(sessionID) {
+    try {
+      const records = loadResumableSessions().filter((record) => record.sessionId !== sessionID);
+      localStorage.setItem(RESUMABLE_SESSIONS_KEY, JSON.stringify(records));
+    } catch (error) {
+      /* ignore persistence failures */
+    }
+  }
+
+  function completedSessionFiles(session) {
+    return (session.files || []).filter((file) => (file.uploadedChunks || []).length >= file.chunkCount);
+  }
+
+  function showRecoveryModal(draft) {
+    const old = document.querySelector(".upload-recovery-overlay");
+    if (old) {
+      old.remove();
+    }
+    const completeCount = completedSessionFiles(draft.session).length;
+    const totalCount = (draft.session.files || []).length;
+    const overlay = document.createElement("div");
+    overlay.className = "upload-recovery-overlay";
+    overlay.setAttribute("role", "dialog");
+    overlay.setAttribute("aria-modal", "true");
+    overlay.setAttribute("aria-labelledby", "upload-recovery-title");
+
+    const modal = document.createElement("div");
+    modal.className = "upload-recovery-modal card";
+    const content = document.createElement("div");
+    content.className = "card-content";
+
+    const title = document.createElement("h2");
+    title.id = "upload-recovery-title";
+    title.textContent = "Unfinished upload found";
+    const copy = document.createElement("p");
+    copy.textContent = `Warpbox found a private draft with ${totalCount} file${totalCount === 1 ? "" : "s"}. ${completeCount} file${completeCount === 1 ? " is" : "s are"} already fully uploaded.`;
+
+    const actions = document.createElement("div");
+    actions.className = "upload-recovery-actions";
+
+    const startOver = document.createElement("button");
+    startOver.type = "button";
+    startOver.className = "button button-danger";
+    startOver.textContent = "New Upload";
+    startOver.addEventListener("click", async () => {
+      startOver.disabled = true;
+      try {
+        await cancelRecoveredDraft();
+        overlay.remove();
+      } catch (error) {
+        startOver.disabled = false;
+        updateStatus(error.message || "Upload draft could not be deleted");
+      }
+    });
+
+    const resume = document.createElement("button");
+    resume.type = "button";
+    resume.className = "button button-primary";
+    resume.textContent = "Resume";
+    resume.addEventListener("click", () => {
+      resumeRecoveredDraft();
+      overlay.remove();
+    });
+
+    actions.append(startOver, resume);
+    content.append(title, copy, actions);
+    modal.append(content);
+    overlay.append(modal);
+    document.body.append(overlay);
+  }
+
+  async function cancelRecoveredDraft() {
+    if (!recoveredDraft) {
+      resetFreshUploadState();
+      return;
+    }
+    const draft = recoveredDraft;
+    updateStatus("Deleting unfinished upload...");
+    await cancelResumableSession(draft.session.sessionId, draft.session.resumeToken);
+    removeResumableSession(draft.session.sessionId);
+    resetFreshUploadState();
+  }
+
+  function resumeRecoveredDraft() {
+    if (!recoveredDraft) {
+      return;
+    }
+    resumeMode = true;
+    selectedFiles = [];
+    renderResumeQueue(recoveredDraft.session, selectedFiles);
+    updateSelectedState();
+    updateStatus("Drop or reselect missing files to continue. Extra files will be added to this upload.");
+  }
+
+  function resetFreshUploadState() {
+    selectedFiles = [];
+    resumeMode = false;
+    recoveredDraft = null;
+    fileInput.value = "";
+    result.hidden = true;
+    if (resultList) {
+      resultList.replaceChildren();
+    }
+    setTotalProgress(0);
+    updateStatus("");
+    updateSelectedState();
+  }
+
+  function uploadedBytesForSessionFile(file, chunkSize) {
+    return (file.uploadedChunks || []).reduce((sum, index) => {
+      const start = index * chunkSize;
+      const end = Math.min(file.size, start + chunkSize);
+      return sum + Math.max(0, end - start);
+    }, 0);
+  }
+
+  function renderRecoveredQueue(items) {
+    if (!uploadQueue) {
+      return;
+    }
+    const rows = [];
+    items.forEach(({ session }) => {
+      (session.files || []).forEach((file) => {
+        const uploadedBytes = uploadedBytesForSessionFile(file, session.chunkSize);
+        const complete = (file.uploadedChunks || []).length >= file.chunkCount;
+        rows.push({
+          name: file.name,
+          size: file.size,
+          uploadedBytes,
+          meta: complete
+            ? `${window.Warpbox.formatBytes(file.size)} · uploaded`
+            : `${window.Warpbox.formatBytes(uploadedBytes)} of ${window.Warpbox.formatBytes(file.size)} · Drop/reselect this file to continue`,
+          progress: percentForBytes(uploadedBytes, file.size),
+          status: complete ? "complete" : "waiting",
+          readonly: true,
+        });
+      });
+    });
+    uploadQueue.hidden = rows.length === 0;
+    uploadQueue.replaceChildren();
+    rows.forEach((row) => uploadQueue.append(createFileRow(row)));
+    const totalBytes = rows.reduce((sum, row) => sum + (row.size || 0), 0);
+    if (totalBytes > 0) {
+      setTotalProgress(percentForBytes(rows.reduce((sum, row) => sum + (row.uploadedBytes || 0), 0), totalBytes));
+    } else if (rows.length > 0) {
+      const completed = rows.filter((row) => row.status === "complete").length;
+      setTotalProgress(percentForBytes(completed, rows.length));
+    }
+  }
+
+  function renderResumeQueue(session, localFiles) {
+    if (!uploadQueue) {
+      return;
+    }
+    const rows = [];
+    const localByNameSize = new Map();
+    (localFiles || []).forEach((file, index) => {
+      localByNameSize.set(`${file.name}:${file.size}`, { file, index });
+    });
+    const usedLocalIndexes = new Set();
+    (session.files || []).forEach((file) => {
+      const uploadedBytes = uploadedBytesForSessionFile(file, session.chunkSize);
+      const complete = (file.uploadedChunks || []).length >= file.chunkCount;
+      const localMatch = localByNameSize.get(`${file.name}:${file.size}`) || null;
+      if (localMatch) {
+        usedLocalIndexes.add(localMatch.index);
+      }
+      rows.push({
+        name: file.name,
+        size: file.size,
+        uploadedBytes,
+        meta: complete
+          ? `${window.Warpbox.formatBytes(file.size)} · uploaded`
+          : localMatch
+            ? `${window.Warpbox.formatBytes(uploadedBytes)} of ${window.Warpbox.formatBytes(file.size)} · ready to resume`
+            : `${window.Warpbox.formatBytes(uploadedBytes)} of ${window.Warpbox.formatBytes(file.size)} · waiting for local file`,
+        progress: percentForBytes(uploadedBytes, file.size),
+        status: complete ? "complete" : localMatch ? "queued" : "waiting",
+        readonly: !localMatch,
+        index: localMatch ? localMatch.index : undefined,
+        removable: Boolean(localMatch && !complete),
+      });
+    });
+    (localFiles || []).forEach((file, index) => {
+      if (usedLocalIndexes.has(index)) {
+        return;
+      }
+      rows.push({
+        name: file.name,
+        meta: `${window.Warpbox.formatBytes(file.size)} · new file`,
+        progress: 0,
+        status: "queued",
+        index,
+        removable: true,
+      });
+    });
+    uploadQueue.hidden = rows.length === 0;
+    uploadQueue.replaceChildren();
+    rows.forEach((row) => uploadQueue.append(createFileRow(row)));
+  }
+
+  function percentForBytes(bytes, total) {
+    if (!total) {
+      return 100;
+    }
+    return Math.max(0, Math.min(100, Math.round((bytes / total) * 100)));
+  }
+
   function renderQueue(files, status) {
     if (!uploadQueue) {
       return;
     }
     uploadQueue.hidden = files.length === 0;
     uploadQueue.replaceChildren();
-    files.forEach((file) => {
+    files.forEach((file, index) => {
       uploadQueue.append(createFileRow({
         name: file.name,
         meta: window.Warpbox.formatBytes(file.size),
         progress: status === "queued" ? 0 : 100,
         status,
+        index,
+        removable: status === "queued",
       }));
     });
   }
 
   function createFileRow(file) {
     const row = document.createElement("div");
-    row.className = "result-item upload-file-row";
+    row.className = `result-item upload-file-row upload-file-${file.status || "queued"}`;
     row.dataset.fileName = file.name;
+    if (typeof file.index === "number") {
+      row.dataset.fileIndex = file.index;
+    }
 
     const body = document.createElement("span");
     const name = document.createElement("strong");
@@ -242,11 +912,53 @@
     fill.style.transform = `scaleX(${file.progress / 100})`;
     bar.append(fill);
     side.append(percent, bar);
+    if (file.status === "waiting") {
+      const badge = document.createElement("small");
+      badge.className = "upload-file-state";
+      badge.textContent = "Needs local file";
+      side.append(badge);
+    }
+    if (file.removable) {
+      const remove = document.createElement("button");
+      remove.className = "upload-file-remove";
+      remove.type = "button";
+      remove.setAttribute("aria-label", `Remove ${file.name}`);
+      remove.textContent = "×";
+      remove.addEventListener("click", () => removeSelectedFile(file.index || 0));
+      side.append(remove);
+    }
 
     row.append(body, side);
     return row;
   }
 
+  function uploadFormData() {
+    const formData = new FormData(form);
+    formData.delete("file");
+    selectedFiles.forEach((file) => {
+      formData.append("file", file, file.name);
+    });
+    return formData;
+  }
+
+  function fileIdentity(file) {
+    return [file.name, file.size, file.lastModified || 0].join(":");
+  }
+
+  async function fileFingerprint(file) {
+    if (!window.crypto || !window.crypto.subtle || !file.slice || typeof TextEncoder === "undefined") {
+      return fileIdentity(file);
+    }
+    const sampleSize = Math.min(file.size, 1024 * 1024);
+    const sample = await file.slice(0, sampleSize).arrayBuffer();
+    const metadata = new TextEncoder().encode([file.name, file.size, file.lastModified || 0, sampleSize].join(":"));
+    const combined = new Uint8Array(metadata.byteLength + sample.byteLength);
+    combined.set(metadata, 0);
+    combined.set(new Uint8Array(sample), metadata.byteLength);
+    const digest = await window.crypto.subtle.digest("SHA-256", combined);
+    return Array.from(new Uint8Array(digest)).map((byte) => byte.toString(16).padStart(2, "0")).join("");
+  }
+
   function setTotalProgress(percent) {
     if (totalProgressBar) {
       totalProgressBar.style.transform = `scaleX(${Math.max(0, Math.min(100, percent)) / 100})`;
@@ -271,4 +983,23 @@
       }
     });
   }
+
+  function setSingleFileProgress(index, file, progress) {
+    if (!uploadQueue) {
+      return;
+    }
+    const row = uploadQueue.querySelector(`.upload-file-row[data-file-index="${index}"]`);
+    if (!row) {
+      return;
+    }
+    const percent = row.querySelector(".file-progress-percent");
+    const fill = row.querySelector(".file-progress span");
+    const normalized = Math.max(0, Math.min(100, progress));
+    if (percent) {
+      percent.textContent = `${normalized}%`;
+    }
+    if (fill) {
+      fill.style.transform = `scaleX(${normalized / 100})`;
+    }
+  }
 })();

backend/templates/pages/admin_settings.html

@@ -126,6 +126,33 @@
             </label>
           </div>
 
+          <div class="settings-section">
+            <h3 class="settings-section-title">Resumable uploads</h3>
+            <label class="checkbox-field">
+              <input type="checkbox" name="resumable_uploads_enabled" {{if .Data.Settings.ResumableUploadsEnabled}}checked{{end}}>
+              <span>Enable browser/API resumable uploads</span>
+            </label>
+            <label>
+              <span>Chunk size (MB)</span>
+              <input name="resumable_chunk_size_mb" value="{{.Data.Settings.ResumableChunkSizeMB}}" required>
+            </label>
+            <label>
+              <span>Draft retention (hours)</span>
+              <input type="number" name="resumable_retention_hours" min="1" value="{{.Data.Settings.ResumableRetentionHours}}" required>
+            </label>
+            <label>
+              <span>Chunk storage</span>
+              <select name="resumable_chunk_mode" required>
+                <option value="same" {{if eq .Data.Settings.ResumableChunkMode "same"}}selected{{end}}>Default local data path</option>
+                <option value="custom" {{if eq .Data.Settings.ResumableChunkMode "custom"}}selected{{end}}>Custom local path, e.g. fast SSD</option>
+              </select>
+            </label>
+            <label>
+              <span>Custom chunk path</span>
+              <input name="resumable_chunk_path" value="{{.Data.Settings.ResumableChunkPath}}" placeholder="/mnt/fast-ssd/warpbox-chunks">
+            </label>
+          </div>
+
           <button class="button button-primary" type="submit">Save settings</button>
         </form>
       </div>

backend/templates/pages/api.html

@@ -14,6 +14,10 @@
         <h2>Endpoints</h2>
         <dl class="endpoint-list">
           <div><dt>Upload</dt><dd><code>POST /api/v1/upload</code></dd></div>
+          <div><dt>Resumable create</dt><dd><code>POST /api/v1/uploads/resumable</code></dd></div>
+          <div><dt>Resumable status</dt><dd><code>GET /api/v1/uploads/resumable/{sessionID}</code></dd></div>
+          <div><dt>Resumable chunk</dt><dd><code>PUT /api/v1/uploads/resumable/{sessionID}/files/{fileID}/chunks/{index}</code></dd></div>
+          <div><dt>Resumable complete</dt><dd><code>POST /api/v1/uploads/resumable/{sessionID}/complete</code></dd></div>
           <div><dt>Health</dt><dd><code>GET /health</code></dd></div>
           <div><dt>Request schema</dt><dd><a href="/api/v1/schemas/upload-request.json"><code>/api/v1/schemas/upload-request.json</code></a></dd></div>
           <div><dt>Response schema</dt><dd><a href="/api/v1/schemas/upload-response.json"><code>/api/v1/schemas/upload-response.json</code></a></dd></div>
@@ -21,6 +25,28 @@
       </div>
     </article>
 
+    <article class="card docs-card docs-card-wide">
+      <div class="card-content">
+        <h2>Resumable uploads</h2>
+        <p>Browser uploads use the resumable API by default. Custom clients can use the same flow: create a session with file metadata, upload exact-sized chunks, then complete the session. Chunks are temporary and are cleaned if the session expires.</p>
+        <pre><code># 1. Create a session.
+curl -s {{.Data.BaseURL}}/api/v1/uploads/resumable \
+  -H 'Accept: application/json' \
+  -H 'Content-Type: application/json' \
+  -d '{"files":[{"name":"report.pdf","size":1048576,"contentType":"application/pdf"}],"expiresMinutes":1440}'
+
+# 2. Upload each chunk using the returned sessionId, file id, and chunkSize.
+dd if=./report.pdf bs=8388608 count=1 skip=0 2>/dev/null | \
+  curl -X PUT --data-binary @- \
+  {{.Data.BaseURL}}/api/v1/uploads/resumable/SESSION_ID/files/FILE_ID/chunks/0
+
+# 3. Complete after all chunks are present. The response is the normal upload JSON.
+curl -X POST -H 'Accept: application/json' \
+  {{.Data.BaseURL}}/api/v1/uploads/resumable/SESSION_ID/complete</code></pre>
+        <p class="muted-copy">For authenticated uploads, send the same <code>Authorization: Bearer &lt;token&gt;</code> header on every resumable request. Incomplete chunks are stored under <code>data/tmp/uploads</code> before finalizing into the selected storage backend.</p>
+      </div>
+    </article>
+
     <article class="card docs-card">
       <div class="card-content">
         <h2>Curl upload</h2>

backend/templates/pages/download.html

@@ -24,6 +24,12 @@
       {{end}}
 
       {{if .Data.Files}}
+        {{$processing := false}}{{range .Data.Files}}{{if .Processing}}{{$processing = true}}{{end}}{{end}}
+        {{if $processing}}
+          <div class="upload-processing-alert" role="status">
+            Some files are still processing. You can share this link now, but processing files will become available shortly.
+          </div>
+        {{end}}
         {{$single := eq (len .Data.Files) 1}}
         <div class="badge-row">
           <span class="badge badge-expiry">Expires {{.Data.ExpiresLabel}}</span>
@@ -74,8 +80,8 @@
           </div>
           <div class="download-list file-browser is-thumbs" data-file-browser>
             {{range .Data.Files}}
-              <article class="download-item file-card" data-kind="{{.PreviewKind}}" data-file-context data-preview-url="{{.URL}}" data-view-url="{{.DownloadURL}}?inline=1" data-download-url="{{.DownloadURL}}" data-file-name="{{.Name}}" data-reaction-card data-react-url="{{.ReactURL}}" data-reacted="{{if .Reacted}}true{{else}}false{{end}}">
-                <a class="file-open" href="{{.DownloadURL}}?inline=1"{{if not $single}} target="_blank" rel="noopener noreferrer"{{end}} aria-label="Open {{.Name}}">
+              <article class="download-item file-card {{if .Processing}}is-processing{{end}}" data-kind="{{.PreviewKind}}" {{if not .Processing}}data-file-context data-preview-url="{{.URL}}" data-view-url="{{.DownloadURL}}?inline=1" data-download-url="{{.DownloadURL}}"{{end}} data-file-name="{{.Name}}" data-reaction-card data-react-url="{{.ReactURL}}" data-reacted="{{if .Reacted}}true{{else}}false{{end}}">
+                {{if .Processing}}<div class="file-open" aria-label="{{.Name}} is processing">{{else}}<a class="file-open" href="{{.DownloadURL}}?inline=1"{{if not $single}} target="_blank" rel="noopener noreferrer"{{end}} aria-label="Open {{.Name}}">{{end}}
                   <span class="file-media">
                     {{if .HasThumbnail}}
                       <img class="file-thumb" src="{{.ThumbnailURL}}" alt="" loading="lazy">
@@ -86,11 +92,11 @@
                   </span>
                   <span class="file-main">
                     <strong class="file-name" title="{{.Name}}">{{.Name}}</strong>
-                    <small>{{.Size}} · {{.ContentType}}</small>
+                    <small>{{.Size}} · {{if .Processing}}Processing{{else}}{{.ContentType}}{{end}}</small>
                   </span>
-                  <span class="file-type">{{.ContentType}}</span>
+                  <span class="file-type">{{if .Processing}}Processing{{else}}{{.ContentType}}{{end}}</span>
                   <span class="file-size">{{.Size}}</span>
-                </a>
+                {{if .Processing}}</div>{{else}}</a>{{end}}
                 {{if not $.Data.Locked}}
                   <div class="file-reaction-dock" data-reaction-dock>
                     <div class="file-reactions" data-reaction-list>

backend/templates/pages/home.html

@@ -77,6 +77,7 @@
         <div class="form-footer">
           <p id="file-summary">Choose one or more files to begin.</p>
           <button class="button button-primary" type="submit">Upload files</button>
+          <button class="button button-danger upload-new-button" type="button" id="new-upload" hidden>New upload</button>
         </div>
       </div>
     </div>

scripts/env/dev.env.example

@@ -9,6 +9,11 @@ WARPBOX_CLEANUP_ENABLED=true
 WARPBOX_CLEANUP_EVERY=1h
 WARPBOX_THUMBNAIL_ENABLED=true
 WARPBOX_THUMBNAIL_EVERY=1m
+WARPBOX_RESUMABLE_UPLOADS_ENABLED=true
+WARPBOX_RESUMABLE_CHUNK_MB=16
+WARPBOX_RESUMABLE_RETENTION_HOURS=1
+WARPBOX_RESUMABLE_CHUNK_MODE=same
+WARPBOX_RESUMABLE_CHUNK_PATH=
 WARPBOX_MAX_UPLOAD_SIZE_MB=16384
 WARPBOX_ANONYMOUS_UPLOADS_ENABLED=true
 WARPBOX_ANONYMOUS_MAX_UPLOAD_MB=512