docs: update project positioning comparison

README.md

@@ -9,17 +9,75 @@
 [![Docker Image](https://img.shields.io/badge/ghcr.io-saltbo%2Fzpan-blue)](https://ghcr.io/saltbo/zpan)
 [![License](https://img.shields.io/github/license/saltbo/zpan.svg)](https://github.com/saltbo/zpan/blob/master/LICENSE)
 
-> Image bed, file sharing, and backup — powered by S3, deployed anywhere.
+> A restrained S3 web drive for image hosting, file sharing, and direct-to-object-storage workflows.
 
 ## What is ZPan?
 
-ZPan is a lightweight file hosting platform built on top of S3-compatible storage. Files upload directly from the client to S3, bypassing server bandwidth entirely.
+ZPan is a lightweight file hosting platform built on top of S3-compatible storage. Files upload directly from the client to S3 through presigned URLs, bypassing server bandwidth entirely. The server is the control plane: auth, metadata, shares, quotas, teams, WebDAV, tool integrations, and admin operations.
 
-**Three scenarios, one platform:**
+The product boundary is intentional: ZPan is an S3-native web drive, not a wrapper around every consumer cloud drive and not a full groupware suite. You bring an S3-compatible bucket; ZPan gives it a clean web UI, public sharing, image-hosting APIs, and deployment options that do not require a VPS or NAS.
 
-- **Image Bed** — Upload via PicGo / ShareX / API, get a URL instantly
-- **File Sharing** — Upload files, generate share links, distribute to anyone
-- **File Backup** — CLI agent syncs local directories to S3/R2
+**Core scenarios:**
+
+- **S3 web drive** — Manage files, folders, previews, trash, quotas, and team workspaces on top of your own object storage
+- **Image hosting** — Upload via PicGo, PicList, uPic, ShareX, Flameshot, or API and get a stable URL instantly
+- **File sharing** — Publish share links with password, expiration, download limits, direct links, and save-to-drive flows
+- **Personal homepage** — Give each user a public `/u/username` page for curated shared files and folder-style browsing
+- **External access** — Mount files through WebDAV and run downloader workers for remote-download workflows
+
+## Why ZPan?
+
+**S3 only, by design.** ZPan does not chase every net-disk provider or build a cloud-drive nesting layer. The storage contract stays simple and durable: S3-compatible buckets such as Cloudflare R2, AWS S3, Backblaze B2, MinIO, RustFS, Tigris, and other S3-compatible services.
+
+**Serverless native.** ZPan is built around Cloudflare Workers, D1, Hono, and web-standard APIs, with Docker and other runtimes as additional deployment targets. You can run a real file-hosting control plane without owning a VPS, keeping a NAS online, or proxying uploads through a long-running server.
+
+**Direct transfer path.** Uploads and downloads use presigned object-storage URLs whenever possible. That keeps server bandwidth low, avoids a central file-transfer bottleneck, and lets object storage do the heavy lifting.
+
+**Practical file workflows.** ZPan includes a web file manager, public sharing, image-hosting configuration, API keys, WebDAV access, teams, quotas, remote-download tasks, file previews, and admin controls without turning into a provider-aggregation platform.
+
+**Deployable downloader workers.** Remote download does not have to run inside the main ZPan instance. You can deploy the downloader together with ZPan for a simple setup, or run it separately in an environment with better network access and fewer source-site restrictions, then let ZPan import the completed files into object storage.
+
+## Product Boundaries
+
+ZPan is a good fit when you want:
+
+- A restrained S3-backed web drive instead of a storage-provider zoo
+- A self-hosted image bed and file-sharing app backed by your own bucket
+- Cloudflare-native deployment without maintaining a VPS or NAS
+- Browser-to-S3 transfers instead of app-server file proxying
+- Tool integrations for screenshot, publishing, WebDAV, remote download, and API-driven workflows
+
+ZPan is not trying to be:
+
+- A real-time document co-editing suite like Nextcloud Office
+- A general-purpose cloud-drive aggregator like AList
+- A local server directory browser like File Browser
+
+## How ZPan Compares
+
+Most self-hosted file projects start from either server files, desktop sync, collaboration, or many-provider aggregation. ZPan starts from S3-compatible object storage and a serverless-friendly control plane.
+
+| Capability | **ZPan** | [Cloudreve](https://docs.cloudreve.org/en/) | [AList](https://alist-repo.github.io/docs/guide/drivers/) | [Nextcloud](https://nextcloud.com/files/) | [Seafile](https://www.seafile.com/en/features/) | [File Browser](https://github.com/filebrowser/filebrowser) |
+|------------|----------|------------|--------|-----------|---------|--------------|
+| S3-native product focus | ✅ | ❌ | ❌ | ❌ | ❌ | ❌ |
+| S3-compatible storage backend | ✅ | ✅ | ✅ | ✅ | ⚠️ | ❌ |
+| Direct browser-to-object-storage path | ✅ | ⚠️ | ⚠️ | ❌ | ❌ | ❌ |
+| Cloudflare Workers native | ✅ | ❌ | ❌ | ❌ | ❌ | ❌ |
+| No VPS/NAS required | ✅ | ❌ | ❌ | ❌ | ❌ | ❌ |
+| PicGo/ShareX image-hosting workflow | ✅ | ❌ | ❌ | ❌ | ❌ | ❌ |
+| Per-user public file homepage | ✅ | ⚠️ | ⚠️ | ⚠️ | ⚠️ | ❌ |
+| Remote download workflow | ✅ | ✅ | ✅ | ❌ | ❌ | ❌ |
+| Separately deployable downloader/node | ✅ | ✅ | ⚠️ | ❌ | ❌ | ❌ |
+| Multi net-disk aggregation | ❌ | ❌ | ✅ | ⚠️ | ❌ | ❌ |
+| Server local directory as primary file root | ❌ | ⚠️ | ⚠️ | ⚠️ | ❌ | ✅ |
+| Real-time document co-editing | ❌ | ❌ | ❌ | ✅ | ⚠️ | ❌ |
+| Dedicated sync clients | Planned | ❌ | ❌ | ✅ | ✅ | ❌ |
+| Team/workspace model | ✅ | ⚠️ | ❌ | ✅ | ✅ | ❌ |
+| WebDAV access | ✅ | ✅ | ✅ | ✅ | ✅ | ❌ |
+| Share links | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ |
+| Docker deployment | ✅ | ✅ | ✅ | ✅ | ✅ | ✅ |
+
+Legend: ✅ first-class or core capability; ⚠️ partial, edition-dependent, or not the product's main focus; ❌ not a core capability.
 
 ## Deploy
 
@@ -80,14 +138,6 @@ After startup:
 - [Roadmap](V2_ROADMAP.md)
 - [Contributing](CONTRIBUTING.md)
 
-## Why ZPan?
-
-- **Zero bandwidth bottleneck** — files transfer directly between client and S3
-- **Zero ops option** — deploy to Cloudflare Workers for free, no server needed
-- **Self-host friendly** — Docker deployment with any S3-compatible storage
-- **Tool ecosystem** — works with PicGo, ShareX, Flameshot out of the box
-- **Open source** — free forever for self-hosted users
-
 ## v1
 
 Looking for ZPan v1 (Go version)? See the [v1 branch](https://github.com/saltbo/zpan/tree/v1).