# Technical Specification: mcp-synology-filestation

## Overview

MCP server exposing Synology FileStation as Claude tools. Communicates with the DSM Web API
over HTTPS. All file operations target a single NAS instance configured at setup time.

---

## Architecture

```
CLI (click)
  └── AppConfig + AuthManager
        └── FileStationClient (httpx, async)
              └── FastMCP server
                    └── tools/filestation.py  (register_filestation)
```

- **Transport:** MCP stdio (Claude Desktop integration)
- **HTTP:** httpx async, HTTPS only in production
- **Session:** DSM session ID (`_sid`) injected into every request; transparent re-auth on
  session expiry (codes 106, 107, 119) with exactly one retry
- **Config:** `~/.config/mcp-synology-filestation/config.yaml`
- **Credentials:** OS keyring (service: `mcp-synology-filestation`)

---

## Auth Flow

1. `mcp-synology-filestation setup` collects NAS host, port, HTTPS flag, username, password.
2. Credentials stored in OS keyring; connection config written to YAML.
3. On `serve`, `AuthManager.login()` calls `SYNO.API.Auth::login` and holds the session ID
   in memory only — never written to disk or logged.
4. If login requires 2FA: user runs `setup` interactively; the OTP + device token are handled
   by the setup wizard; the device token is stored in keyring for subsequent logins.
5. Credential resolution order: env vars → OS keyring → (forbidden: plaintext config).

### Environment variable overrides

| Variable | Purpose |
|----------|---------|
| `SYNOLOGY_HOST` | Override NAS hostname |
| `SYNOLOGY_USERNAME` | Override DSM username |
| `SYNOLOGY_PASSWORD` | Override DSM password (not stored) |

---

## DSM API Endpoints

All requests use `GET /webapi/entry.cgi` with query parameters unless noted.

| API | Version | Methods used |
|-----|---------|--------------|
| `SYNO.API.Auth` | 7 | `login`, `logout` |
| `SYNO.FileStation.Info` | 2 | `get` |
| `SYNO.FileStation.List` | 2 | `list_share`, `list`, `getinfo` |
| `SYNO.FileStation.Search` | 2 | `start`, `list`, `stop`, `clean` |
| `SYNO.FileStation.Download` | 2 | `download` |
| `SYNO.FileStation.Upload` | 3 | `upload` (POST multipart) |
| `SYNO.FileStation.CreateFolder` | 2 | `create` |
| `SYNO.FileStation.Rename` | 2 | `rename` |
| `SYNO.FileStation.CopyMove` | 3 | `start`, `status`, `stop` |
| `SYNO.FileStation.Delete` | 2 | `start`, `status`, `stop` |
| `SYNO.FileStation.Compress` | 3 | `start`, `status`, `stop` |
| `SYNO.FileStation.Extract` | 2 | `start`, `status`, `stop` |
| `SYNO.FileStation.DirSize` | 2/1 | `start` (v2), `status` (v1) |
| `SYNO.FileStation.MD5` | 2/1 | `start` (v2), `status` (v1) |
| `SYNO.FileStation.CheckPermission` | 3 | `write` |
| `SYNO.FileStation.Sharing` | 3 | `create`, `list`, `delete` |

### Async task pattern (CopyMove, Delete, Search, Compress, Extract)

DSM returns a `taskid` from `start`; the client polls `status` with exponential backoff
(initial 200 ms, max 2 s, timeout 60 s) until `finished=true`, then calls `stop`/`clean`.
Implemented in `_poll_task()`.

### One-shot task pattern (DirSize, MD5)

`DirSize` and `MD5` differ from the async task pattern: DSM delivers `finished=true` exactly
once, then immediately discards the result (subsequent polls return error 599). Implemented
in `_start_and_poll_oneshot()`:

1. Call `start`.
2. Poll `status` repeatedly until `finished=true` or timeout.
3. On 599: if within the first ~8 s after start, the background service may still be warming
   up ("cold start") — restart the task and try again (up to 6 restarts).
4. On `finished=true`: return the data and stop polling (never poll again).

**Cold-start behaviour:** After a period of inactivity, DSM's DirSize/MD5 background service
takes ~6–8 s to initialise. During this window every `status` poll returns error 599. The
correct recovery is to wait a moment, then restart the task. Retrying the same `taskid` does
not help — the service must be cold-started via a new `start` call.

**DirSize `status` version:** Must use `version=1`. Using `version=2` always returns 599
regardless of service state.

---

## Tools (v0.2.10 — 20 tools)

### Read-only

| Tool | Description |
|------|-------------|
| `list_shares` | List all shared folders with volume usage |
| `list_dir` | List directory contents with pagination and sorting |
| `get_info` | Get detailed metadata for one or more paths |
| `check_exist` | Check if one or more paths exist (Yes/No table) |
| `search` | Search for files by glob pattern with async polling |
| `download` | Download a file as base64 (max 10 MB) |
| `dir_size` | Total size, file count, folder count for directories |
| `get_md5` | Compute MD5 checksum of a file |

### Write

| Tool | Description |
|------|-------------|
| `create_folder` | Create a new folder (optionally with parent dirs) |
| `rename` | Rename a file or folder |
| `copy` | Copy a file or folder (async polling, overwrite=False default) |
| `move` | Move a file or folder (async polling, overwrite=False default) |
| `delete` | Delete a file or folder — requires confirmed=True |
| `upload` | Upload base64-encoded content to a path (max 50 MB) |
| `compress` | Compress paths into a ZIP or 7z archive |
| `extract` | Extract a ZIP or 7z archive to a destination folder |

### Permission & Sharing

| Tool | Description |
|------|-------------|
| `check_permission` | Check write permission for a filename in a directory |
| `create_sharing_link` | Create a public sharing link (optional password + expiry) |
| `list_sharing_links` | List all sharing links (paginated table) |
| `delete_sharing_link` | Delete a sharing link by ID |

---

### Tool details

#### `list_shares`
**Parameters:** none

**Returns:** Formatted table of share names, paths, and volume usage.

**DSM call:** `SYNO.FileStation.List::list_share`
```
additional=["volume_status"]
```

> **Note:** DSM returns share paths directly (e.g. `/dev`, `/data`). The `path` field from the
> response is used as-is — do not prepend the volume prefix.

---

#### `list_dir`
**Parameters:**
| Name | Type | Required | Default | Description |
|------|------|----------|---------|-------------|
| `path` | str | yes | — | Share-relative path (e.g. `/dev`, `/data/photos`) |
| `offset` | int | no | 0 | Number of items to skip |
| `limit` | int | no | 100 | Max items to return (max 500) |
| `sort_by` | str | no | `name` | `name`, `size`, `user`, `group`, `mtime`, `atime`, `crtime`, `posix`, `type` |
| `sort_direction` | str | no | `asc` | `asc` or `desc` |

**Returns:** Table of entries (name, type, size, modified time). Includes total count for
pagination context.

**DSM call:** `SYNO.FileStation.List::list`
```
folder_path={path}, offset={offset}, limit={limit},
sort_by={sort_by}, sort_direction={sort_direction},
additional=["size","time"]
```

> **Path requirement:** `folder_path` must be a share path as returned by `list_share`
> (e.g. `/dev`, `/data`). Volume paths (`/volume1/dev`) are **not accepted** and cause DSM
> error 408.
>
> **`additional` format:** Must be a JSON array serialised as a string
> (`json.dumps(["size","time"])` → `'["size", "time"]'`). A comma-separated string
> (`"size,time"`) is silently ignored by DSM.

---

#### `get_info`
**Parameters:**
| Name | Type | Required | Description |
|------|------|----------|-------------|
| `path` | str | yes | One or more share-relative paths, comma-separated |

**Returns:** Table with type, size, owner, group, permissions (octal), modification time,
creation time, and real volume path for each requested item.

**DSM call:** `SYNO.FileStation.List::getinfo`
```
path=json.dumps([paths...]),
additional=["real_path","size","time","perm","owner","type"]
```

---

#### `check_exist`
**Parameters:**
| Name | Type | Required | Description |
|------|------|----------|-------------|
| `path` | str | yes | One or more share-relative paths, comma-separated |

**Returns:** Yes/No table per path.

**DSM call:** `SYNO.FileStation.List::getinfo` — entries with `name=null` are non-existent.

---

#### `search`
**Parameters:**
| Name | Type | Required | Default | Description |
|------|------|----------|---------|-------------|
| `path` | str | yes | — | Root directory to search from |
| `pattern` | str | yes | — | Filename glob pattern (e.g. `*.log`) |
| `recursive` | bool | no | true | Search subdirectories |
| `max_results` | int | no | 200 | Cap on returned matches |

**Returns:** List of matching paths with type, size, and modification time.

**DSM calls:** `SYNO.FileStation.Search::start` → poll `::list` → `::stop` + `::clean`

---

#### `download`
**Parameters:**
| Name | Type | Required | Description |
|------|------|----------|-------------|
| `path` | str | yes | Share-relative file path |

**Returns:** JSON `{filename, size, content_base64}`. Files > 10 MB return an error.

**DSM call:** `SYNO.FileStation.Download::download` (streaming GET, `mode=download`)

---

#### `dir_size`
**Parameters:**
| Name | Type | Required | Description |
|------|------|----------|-------------|
| `path` | str | yes | Comma-separated share-relative paths |

**Returns:** Table with total size, file count, folder count.

**DSM calls:** `SYNO.FileStation.DirSize::start` (v2) → poll `::status` (v1)

> See *One-shot task pattern* above for polling behaviour and cold-start recovery.

---

#### `get_md5`
**Parameters:**
| Name | Type | Required | Description |
|------|------|----------|-------------|
| `path` | str | yes | Share-relative file path |

**Returns:** `MD5 of {path}: {hash}`

**DSM calls:** `SYNO.FileStation.MD5::start` (v2) → poll `::status` (v1)

---

#### `create_folder`
**Parameters:**
| Name | Type | Required | Default | Description |
|------|------|----------|---------|-------------|
| `path` | str | yes | — | Parent directory path |
| `name` | str | yes | — | New folder name |
| `create_parents` | bool | no | false | Create missing parent directories |

**DSM call:** `SYNO.FileStation.CreateFolder::create`

---

#### `rename`
**Parameters:**
| Name | Type | Required | Description |
|------|------|----------|-------------|
| `path` | str | yes | Current share-relative path |
| `new_name` | str | yes | New filename (bare name, not full path) |

**DSM call:** `SYNO.FileStation.Rename::rename`

---

#### `copy`
**Parameters:**
| Name | Type | Required | Default | Description |
|------|------|----------|---------|-------------|
| `src` | str | yes | — | Source path |
| `dst` | str | yes | — | Destination directory path |
| `overwrite` | bool | no | false | Overwrite if destination exists |

**DSM call:** `SYNO.FileStation.CopyMove::start` (async, `remove_src=false`)

---

#### `move`
**Parameters:**
| Name | Type | Required | Default | Description |
|------|------|----------|---------|-------------|
| `src` | str | yes | — | Source path |
| `dst` | str | yes | — | Destination directory path |
| `overwrite` | bool | no | false | Overwrite if destination exists |

**DSM call:** `SYNO.FileStation.CopyMove::start` (async, `remove_src=true`)

---

#### `delete`
**Destructive — requires `confirmed=True`.**

**Parameters:**
| Name | Type | Required | Default | Description |
|------|------|----------|---------|-------------|
| `path` | str | yes | — | Path to delete |
| `confirmed` | bool | yes | false | Must be `true` to proceed |

**Returns:**
- `confirmed=false`: Preview of what would be deleted.
- `confirmed=true`: Success message or error.

**DSM call:** `SYNO.FileStation.Delete::start` (async, `recursive=true`)

---

#### `upload`
**Parameters:**
| Name | Type | Required | Default | Description |
|------|------|----------|---------|-------------|
| `path` | str | yes | — | Destination directory path |
| `filename` | str | yes | — | Filename to create |
| `content_base64` | str | yes | — | Base64-encoded file content |
| `overwrite` | bool | no | false | Overwrite if file exists |
| `create_parents` | bool | no | true | Create missing parent directories |

**Returns:** Full path of uploaded file. Files > 50 MB are rejected.

**DSM call:** `SYNO.FileStation.Upload::upload` (POST multipart/form-data)

---

#### `compress`
**Parameters:**
| Name | Type | Required | Default | Description |
|------|------|----------|---------|-------------|
| `paths` | list[str] | yes | — | Paths to compress |
| `dest_file_path` | str | yes | — | Output archive path incl. filename |
| `level` | str | no | `moderate` | `store`/`fastest`/`fast`/`normal`/`moderate`/`maximum` |
| `mode` | str | no | `add` | `add`/`update`/`refreshen` |
| `format` | str | no | `zip` | `zip` or `7z` |
| `password` | str | no | `""` | Archive password |

**DSM call:** `SYNO.FileStation.Compress::start` (async, v3)

---

#### `extract`
**Parameters:**
| Name | Type | Required | Default | Description |
|------|------|----------|---------|-------------|
| `file_path` | str | yes | — | Archive path on NAS |
| `dest_folder_path` | str | yes | — | Destination directory |
| `overwrite` | bool | no | false | Overwrite existing files |
| `keep_dir` | bool | no | true | Preserve directory structure |
| `create_subfolder` | bool | no | false | Extract into a subfolder |
| `password` | str | no | `""` | Archive password |

**DSM call:** `SYNO.FileStation.Extract::start` (async, v2)

---

#### `check_permission`
**Parameters:**
| Name | Type | Required | Default | Description |
|------|------|----------|---------|-------------|
| `path` | str | yes | — | Directory to check |
| `filename` | str | yes | — | Filename to check write access for |
| `overwrite` | bool | no | false | Check overwrite permission |
| `create_only` | bool | no | false | Check create-only permission |

**Returns:** `"Permission granted: write {filename} into {path}"` or `"Error: …"`

**DSM call:** `SYNO.FileStation.CheckPermission::write` (v3)

> **Parameter format:** `path` and `filename` are passed as plain strings (no `json.dumps`).
> On success, DSM returns `{"blSkip": false}` — the tool maps this to a human-readable message.

---

#### `create_sharing_link`
**Parameters:**
| Name | Type | Required | Default | Description |
|------|------|----------|---------|-------------|
| `path` | str | yes | — | File or folder path to share |
| `password` | str | no | `""` | Password to protect the link |
| `date_expired` | str | no | `""` | Expiry date (`YYYY-MM-DD`) |
| `date_available` | str | no | `""` | Availability start date (`YYYY-MM-DD`) |

**Returns:** Sharing URL + link ID, with password-protection flag.

**DSM call:** `SYNO.FileStation.Sharing::create` (v3)

> `path` must be `json.dumps()`-encoded. The `date_expired`/`date_available` fields are not
> echoed back in the create response — confirm via `list_sharing_links` if needed.

---

#### `list_sharing_links`
**Parameters:**
| Name | Type | Required | Default | Description |
|------|------|----------|---------|-------------|
| `offset` | int | no | 0 | Pagination offset |
| `limit` | int | no | 100 | Max links to return |

**Returns:** Table with ID, URL, path, owner, expiry, status. Includes total count and
pagination hint when more results are available.

**DSM call:** `SYNO.FileStation.Sharing::list` (v3)

---

#### `delete_sharing_link`
**Parameters:**
| Name | Type | Required | Description |
|------|------|----------|-------------|
| `link_id` | str | yes | Sharing link ID (from `list_sharing_links`) |

**Returns:** `"Deleted sharing link: {link_id}"` or error.

**DSM call:** `SYNO.FileStation.Sharing::delete` (v3)

> `link_id` must be passed as `json.dumps(link_id)` in the `id` parameter.

---

## Error Handling Strategy

### Principles
1. DSM error codes are mapped to human-readable messages before surfacing to Claude.
2. Never expose raw stack traces or session IDs in tool responses.
3. Auth errors (codes 400–403) trigger a clear message with a hint to run `setup`.
4. Session expiry errors (106, 107, 119) are retried once transparently.
5. Network errors (timeouts, connection refused) are reported as
   "Cannot reach NAS at {host} — check connectivity."
6. Unknown DSM error codes are reported as "DSM error {code}: {raw_message}".

### DSM error code map

| Code | Meaning | User message |
|------|---------|--------------|
| 100 | Unknown error | "DSM reported an unknown error." |
| 101 | Invalid parameter | "Invalid parameter in request." |
| 102 | API does not exist | "This DSM API is not available on your NAS." |
| 103 | Method does not exist | "This DSM API method is not supported." |
| 105 | Permission denied | "Permission denied — check your DSM account privileges." |
| 106 | Session timeout | (transparent re-auth) |
| 107 | Session displaced | (transparent re-auth) |
| 119 | Invalid session | (transparent re-auth) |
| 400 | Invalid password | "Login failed — check username and password (run setup)." |
| 401 | Guest or disabled account | "DSM account is disabled." |
| 403 | 2FA required | "Two-factor authentication required — run setup." |
| 404 | 2FA failed | "OTP code incorrect." |
| 408 | Device token required | "Device token required — run setup again." |
| 599 | Background service not ready | (handled by `_start_and_poll_oneshot` — restart task) |
| 1800 | File not found | "File or folder not found: {path}" |
| 1801 | No write permission | "No write permission for: {path}" |
| 1802 | File exists | "A file already exists at this path." |
| 1803 | Disk quota exceeded | "Disk quota exceeded." |
| 1804 | No space left | "No space left on the target volume." |
| 1805 | Filename too long | "Filename too long." |
| 1806 | Illegal filename characters | "Filename contains illegal characters." |
| 1807 | File is read-only | "File is read-only." |

---

## DSM API Quirks

### Parameter encoding

- **JSON array parameters** (`path`, `additional`, etc.) must be serialised with
  `json.dumps()`. A plain Python list or comma-separated string is silently ignored
  by DSM — the field will be absent from the response.
- **`path` for multi-item operations** (e.g. `List::getinfo`, `DirSize::start`):
  always pass as `json.dumps(["/path1", "/path2"])`, even for a single path.
- **`path` for single-item operations** (e.g. `CopyMove::start`, `Rename::rename`,
  `Sharing::create`): pass as `json.dumps("/path")` (a JSON-encoded string).
- **`Sharing::delete` `id` parameter:** must be `json.dumps(link_id)` — plain string
  is not accepted.
- **`CheckPermission::write` `path` and `filename`:** pass as plain strings (no
  `json.dumps`).
- **Share paths vs. volume paths:** always use share paths (`/docker`, `/homes/marcus`).
  Volume paths (`/volume1/docker`) cause DSM error 408.

### APIs confirmed NOT available on this NAS

| API | Status | Workaround |
|-----|--------|------------|
| `SYNO.FileStation.Stat` | Not in API registry | Use `List::getinfo` |
| `SYNO.FileStation.CheckExist` | Returns error 400 | Use `List::getinfo` (entries with `name=null` don't exist) |

### FastMCP `outputSchema` / tools/list payload limit

Do **not** add `-> str` return type annotations to `@mcp.tool()` functions. FastMCP
infers `outputSchema` from the annotation, which doubles the tools/list payload size.
Claude Desktop truncates the tool list when the payload exceeds its limit, making some
tools invisible. Omitting the return annotation suppresses `outputSchema` generation.

### DirSize / MD5 one-shot behaviour

`DirSize` and `MD5` tasks are consumed on first read: `finished=true` is returned exactly
once, then the task is deleted and all subsequent `status` polls return error 599.
Implementation: `_start_and_poll_oneshot()` — never call `status` a second time after
receiving `finished=true`.

### DirSize cold-start

After a period of inactivity, DSM's DirSize background service needs ~6–8 s to initialise.
During cold start, `status` returns 599 on every poll. The fix is to wait briefly and
**restart** the task (new `start` call) — polling the original `taskid` again does not help.
`_start_and_poll_oneshot()` retries up to 6 task restarts before giving up.

### DirSize `status` API version

`SYNO.FileStation.DirSize::status` must be called with `version=1`. Using `version=2`
always returns error 599 regardless of whether the background service is running.

---

## Configuration Model

```yaml
# ~/.config/mcp-synology-filestation/config.yaml
connection:
  host: dsm.gecheckt.de
  port: 443
  https: true
  verify_ssl: true
  timeout: 30

auth:
  username: marcus
  # password: never stored here — OS keyring only
```

### AppConfig fields

| Field | Type | Default | Description |
|-------|------|---------|-------------|
| `connection.host` | str | required | NAS hostname or IP |
| `connection.port` | int | 443/5000 | DSM port |
| `connection.https` | bool | true | Use HTTPS |
| `connection.verify_ssl` | bool | true | Verify TLS cert |
| `connection.timeout` | int | 30 | Request timeout (seconds) |
| `auth.username` | str | required | DSM username |

`base_url` is derived as `{https_scheme}://{host}:{port}`.
`keyring_service` is fixed to `"mcp-synology-filestation"`.

---

## CLI Subcommands

### `setup`
Interactive wizard:
1. Prompt for NAS host, port, HTTPS, SSL verify.
2. Prompt for username and password (masked).
3. Attempt login; detect 2FA requirement.
4. If 2FA: prompt OTP, request device token, store token in keyring.
5. Verify FileStation API availability (`SYNO.FileStation.List`).
6. Save config to `~/.config/mcp-synology-filestation/config.yaml`.
7. Print Claude Desktop snippet.

### `check`
Validate config, resolve credentials, test login, list available FileStation APIs.

### `serve`
Load config and credentials, create `FileStationClient` (lazy — no immediate connection),
create and run `FastMCP("mcp-synology-filestation")` over stdio. Uses `anyio.run()` for
Windows compatibility.

---

## Roadmap

### v0.2 — complete (20 tools)

All tools shipped in v0.2.10:

**Group 1:** `list_shares`, `list_dir`, `get_info`, `check_exist`, `search`, `download`
**Group 2:** `create_folder`, `rename`, `copy`, `move`, `delete`, `upload`, `compress`,
`extract`, `dir_size`, `get_md5`
**Group 3:** `check_permission`, `create_sharing_link`, `list_sharing_links`,
`delete_sharing_link`

### v0.3 — candidates

| Tool | API | Notes |
|------|-----|-------|
| `get_thumbnail` | `SYNO.FileStation.Thumb` | Return base64 thumbnail for image/video |
| `list_favorites` | `SYNO.FileStation.Favorite` | List user-pinned favourite paths |
| `add_favorite` | `SYNO.FileStation.Favorite` | Pin a path as favourite |
| `delete_favorite` | `SYNO.FileStation.Favorite` | Remove a favourite |
| `list_snapshots` | `SYNO.FileStation.Snapshot` | List Btrfs snapshots for a share |
| `background_tasks` | `SYNO.FileStation.BackgroundTask` | List/cancel background operations |