feat: groups refactor Phase 1 — root RO/RW model + shared directories UI

Replace the upload boolean with per-root writable/removable/ejected flags.
Backend: new ops (update_root, eject_root, plug_root), MNP 1.1 protocol
messages, live RootSet updates so API always reflects current state, CLI
root subcommand (add/remove/set/list/eject/plug).
Frontend: SharedDirectoriesTable with optimistic toggle switches, eject/plug
in Files and Settings, upload gated on root.writable, ejected-root filtering
in all media apps, updated Create Group wizard, 10-locale i18n.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 657 insertions, 0 deletions

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+# Groups Refactor — Per-Root Permissions & App Plugin Architecture
+
+> Status: **Phase 1 implemented.** Phase 2 and 3 not started.
+>
+> This is the most significant refactoring of the project. It changes how roots
+> are permissioned, how group applications are configured, and how the Settings
+> and Create Group pages are structured.
+
+---
+
+## 0. Summary of changes
+
+| Area | Before | After |
+|---|---|---|
+| Root permissions | One root marked `upload=True`; binary `member_upload` toggle per group | Each root is **RO** (default) or **RW**; multiple RW roots allowed; fully RO group is valid |
+| Upload policy | Separate section in Settings; `member_upload` signed op | **Removed.** RO/RW on the root is the mechanism. Files shows Upload only on RW roots. Chat disables attachments when its configured directory is not on a RW root |
+| Root metadata | `name, path, kind, upload, direct` | `name, path, kind, writable, removable, direct` |
+| Removable flag | Not tracked | Per-root boolean, set by operator. Enables the **eject/plug** button for safe device removal |
+| Safe eject | Auto-detected only (`path.is_dir()`) | Operator-initiated eject button in Settings AND Files root view. `ejected` state distinct from `available`. Indexer freezes entries, no data loss |
+| Files app | Can be disabled | **Always enabled**, transparently. Not shown in the app toggle list |
+| App selection at group creation | Checkbox list of all apps | **Removed.** Files is enabled automatically; other apps are configured later in Settings |
+| Settings layout | Monolithic: apps checkboxes, TMDB, MusicBrainz, directories, uploads — all in `group-settings.js` | **Structured:** Shared directories (top, expanded) → per-app sections (each with toggle + icon + title, collapsed, settings hidden until enabled) → Scan/Danger/Devices/Members |
+| App settings code | All inlined in `group-settings.js` (1338 lines) | Each app has `ui/<APP_NAME>-app-settings.js`; loaded by discovery (presence of the file) |
+| App enablement UI | One "Applications" section with checkboxes | Each app is a collapsible section with its own toggle in the title. The toggle is the enablement control |
+| Folder picker | Flat `<select>` with depth-indented names | **Folder tree popup**: modal, root icons, `[+]` expand, sub-directory selection |
+| Server-side app ops | Per-app functions in `ops.py` (`set_video_root`, `set_audio_root`, `set_photo_roots`, ...) | Generic `set_app_directory()` / `set_app_directories()` + app-specific wrappers where needed |
+| CLI | `group add --dir --upload-dir`; `member upload` concept | `group add --dir [--writable]`; `root add/remove/set` with `--writable`/`--read-only`/`--removable` |
+| MNP | 1.0 | 1.1 (additive: new fields on roots, new generic app-directory messages). 1.0 peers still work |
+
+---
+
+## 1. Design decisions
+
+### 1.1 RO/RW replaces upload + member_upload
+
+The current model has two orthogonal mechanisms: (a) one root is the upload target,
+(b) `member_upload` toggles whether non-operators can upload there. The new model
+collapses both into one property per root: **writable**.
+
+- `writable = false` (default): the root is read-only for everyone, including the
+  operator via the UI. Content is placed there out-of-band (filesystem, rsync, USB).
+- `writable = true`: any group member may upload to this root (into the quarantine
+  subdirectory, same protections as today — allowlist, no overwrite, size cap).
+
+Multiple roots can be writable. Zero can be writable (fully read-only group). The
+operator controls which roots are RW by toggling a switch in the shared directories
+table.
+
+**What this removes:**
+- The `member_upload` toggle and its `OP_MEMBER_UPLOAD` signed op
+- The `member_upload` / `member_upload_ack` MNP message types (deprecated, still
+  parsed for backward compat)
+- The Uploads section in Settings
+- The concept of "the upload root" (singular)
+
+**What this preserves:**
+- The quarantine directory, filename allowlist, no-overwrite check, size cap
+- The `_do_file_upload` handler in `webrtc_server.py` — now checks `writable` on
+  the target root instead of checking `upload` + `member_upload`
+- The operator's ability to create a read-only group (set all roots RO)
+
+### 1.2 Files is always enabled
+
+`files` is removed from the toggleable app list. It is always present in
+`enabled_apps` and cannot be disabled. The current ability to hide it was misleading:
+MNP still permits root exploration regardless. The tab bar always shows Files.
+
+`apps.js` keeps `files` in `APPS` but marks it `alwaysEnabled: true`. The Settings
+page skips it when rendering app toggle sections.
+
+### 1.3 Per-app settings files
+
+Each app that has configurable settings exports a settings component from
+`ui/<APP_NAME>-app-settings.js`. The file is optional — an app with no settings
+(like Files today) has no settings file and gets only a toggle.
+
+The `APPS` registry in `apps.js` gains an optional `Settings` field per entry,
+imported from the corresponding settings file. The group-settings page iterates
+`APPS`, skips `files`, and renders a collapsible section for each, with:
+
+- The app's monochrome icon + localized title in the section header
+- A toggle switch in the header (disabled by default)
+- The app's `Settings` component below, **hidden until the toggle is on**
+- A Save button per app section (some saves trigger caching — TMDB, MusicBrainz)
+
+**Discovery mechanism:** In the browser context, "file discovery" is registration in
+`apps.js`. Adding a new app means: write `<APP>-app.js` + `<APP>-app-settings.js`,
+add one entry to `APPS` in `apps.js`, add the key to `ALLOWED_APPS` on the node.
+Server-side enforcement via `ALLOWED_APPS` prevents client-side hacks from enabling
+an unrecognized app.
+
+### 1.4 Folder tree widget
+
+A reusable modal popup (`FolderTreePicker`) that:
+
+- Appears centered on screen, semi-transparent backdrop
+- Lists root directories at the top level, with the same folder icons as Files
+- Each root can be expanded via `[+]` / collapsed via `[-]`, explorer-tree style
+- Sub-directories load from the existing `nodeDirs` data (already available from the
+  file index, no new endpoint needed)
+- Supports **single-select** mode (Chat) and **multi-select** mode (Videos, Music,
+  Photos)
+- Shows the root's RO/RW badge next to each root name
+- For apps that require RW (Chat): RO roots and their children are greyed out /
+  unselectable, with a tooltip explaining why
+- OK / Cancel buttons at the bottom
+- Returns the selected path(s) relative to the root (e.g., `Movies/Action`)
+
+The widget replaces the current flat `<select>` dropdowns in all app settings. It is
+also usable in other UI contexts (the video player's folder navigation already does
+something similar ad-hoc).
+
+### 1.5 Shared directories table
+
+A reusable component (`SharedDirectoriesTable`) used in both the group Settings page
+and the Create Group wizard (developed once, shared). Features:
+
+- Borderless table, one row per root
+- Columns: **Name** (with folder icon), **Path** (truncated with tooltip on hover),
+  **RW toggle** (switch, default off), **Removable toggle** (checkbox),
+  **Eject/Plug button** (visible only when removable is checked — see §1.5b),
+  **Delete button** (trash icon, with confirmation)
+- Ejected roots show a distinct visual state: greyed-out row, eject icon replaced by
+  a plug icon
+- The first root in the Create Group wizard defaults to RW
+- A concise explanatory sentence at the top: "At least one directory is required.
+  Read-write directories accept uploads from group members."
+- Add button: opens the native folder picker (Electron) or a path input (web, admin
+  only)
+- Cannot delete the last root (refused with explanation)
+- Each change is a signed operator op (`ROOT_ADD`, `ROOT_REMOVE`, or new
+  `ROOT_UPDATE` for toggling writable/removable on an existing root)
+
+### 1.5b Safe eject for removable devices
+
+**Problem.** An operator stores data on a USB drive. Unplugging it without warning
+triggers the watchdog — file deletions propagate as though the operator erased an
+entire library. The existing `refresh_availability()` auto-detects this and freezes
+entries (good), but there is no way to eject cleanly before unplugging, and no way
+to re-plug without a full rescan.
+
+**The `ejected` state.** A root has two independent runtime states:
+
+- `ejected` (bool, default `false`): operator-controlled, persisted in `roster.db`.
+  Set by clicking the eject button; cleared by clicking plug.
+- `available` (bool, runtime): computed as `not ejected and is_live()`. This is
+  what clients and the indexer see.
+
+The distinction matters: when the operator clicks "eject" but hasn't physically
+unplugged yet, `is_live()` returns `true` but `available` is `false` because
+`ejected` is `true`. Without this, `refresh_availability()` would immediately
+flip it back to available.
+
+**Eject flow:**
+
+1. Operator clicks the eject button (⏏) on a removable root
+2. Confirmation dialog: "Eject *Movies*? Files from this directory will be
+   temporarily hidden to all members. You can safely unplug the device."
+3. On confirm: `PUT /api/groups/{gid}/roots/{name}/eject` → `ops.eject_root()`
+4. `ops.eject_root()`: sets `ejected = true` in `roster.db`, marks root
+   `available = false`, stops the watchdog observer for that root
+5. The indexer **freezes** all entries from that root (existing behavior — no
+   deletions, no index updates, cached data preserved)
+6. `index_sync` update propagates to connected peers: the root's `available` is
+   now `false`
+7. All apps filter out entries from unavailable roots (Files already does this
+   partially — needs to be complete across Videos, Music, Photos)
+8. The operator can now safely unplug the device
+
+**Plug flow:**
+
+1. Operator plugs the device back in and clicks the plug button (🔌)
+2. `PUT /api/groups/{gid}/roots/{name}/plug` → `ops.plug_root()`
+3. `ops.plug_root()`: checks `is_live()` first — if the path is not accessible,
+   refuses with "Directory not found. Is the device connected?"
+4. On success: sets `ejected = false`, marks root `available = true`, restarts
+   the watchdog observer
+5. The indexer runs a **reconciliation** (not a full rescan) — compares frozen
+   entries against current filesystem state. New/changed/deleted files are
+   handled normally
+6. `index_sync` update propagates — entries reappear in all apps
+
+**Auto-detection safety net.** If a `removable` root's path suddenly disappears
+(operator unplugged without clicking eject):
+
+- `refresh_availability()` detects `is_live() = false`
+- Because `removable = true`, it sets `ejected = true` automatically (as if the
+  operator had clicked eject)
+- Entries freeze, no deletions propagate
+- The root stays in "ejected" state until the operator explicitly plugs it back
+
+For non-removable roots, the existing behavior is unchanged: `available` flips
+based on `is_live()`, entries freeze when unavailable, rescan when available again.
+
+**Eject button in Files app.** In addition to the Settings table, an eject button
+appears in the Files app root-level view, next to each removable root's name. This
+provides quick access without navigating to Settings. Same confirmation dialog,
+same API call. Ejected roots show as greyed-out with a plug icon to re-enable.
+
+**What is NOT deleted on eject:**
+
+- Index entries (frozen, not removed)
+- TMDB / MusicBrainz cached metadata
+- Video thumbnails in `media_cache`
+- Chat message history referencing files on that root
+- App directory configurations pointing to that root (but flagged as temporarily
+  invalid — the app shows a warning, not an error)
+
+**MNP message:** `ROOT_EJECT` / `ROOT_EJECT_ACK` and `ROOT_PLUG` / `ROOT_PLUG_ACK`
+— signed operator ops, same pattern as `ROOT_UPDATE`. Broadcast to all connected
+peers so they see the availability change immediately without waiting for the next
+`index_sync`.
+
+### 1.6 Server-side normalization (ops.py)
+
+Two generic functions replace the per-app specific ones:
+
+```python
+def set_app_directory(state, group_id, app_key, path, *, require_writable=False):
+    """Set a single directory for an app. Validates path is within a named root.
+    If require_writable, refuses paths under RO roots."""
+
+def set_app_directories(state, group_id, app_key, paths, *, require_writable=False):
+    """Set multiple directories for an app. Same validation."""
+```
+
+Existing functions (`set_video_root`, `set_audio_root`, `set_photo_roots`) become
+thin wrappers calling the generic versions, preserving the current MNP message types
+and roster keys for backward compat. New apps use the generic functions directly.
+
+### 1.7 Chat settings additions
+
+- **Directory picker** (single, RW-only): selects the directory for chat file
+  attachments. If no RW root exists, the picker shows an explanation and the
+  attachment button is disabled in the chat UI. If the selected directory's root is
+  later set to RO, the setting is flagged as invalid and attachments are disabled
+  until corrected.
+- **Link preview toggle** (new, server-side): the operator can disable link previews
+  for the group. Stored in `roster.db` as `chat_link_preview` (default: enabled).
+  The node's `linkpreview.py` checks this setting before unfurling. The toggle is a
+  `ToggleSwitch` in the Chat settings section.
+
+### 1.8 Videos/Music/Photos settings changes
+
+**Videos:**
+- Directory picker changes from single to **multi-directory** (via folder tree widget)
+- TMDB settings section moved here from the monolithic settings
+- TMDB API key field: no longer says "optional" or mentions the default key.
+  Instead, a prompt to sign up on TMDB with a direct link to generate a key
+- Per-app Save button triggers TMDB cache sweep
+
+**Music:**
+- Directory picker changes from single to **multi-directory**
+- MusicBrainz settings section moved here
+- Per-app Save button triggers MusicBrainz cache sweep
+
+**Photos:**
+- Multi-directory picker (already multi, just moves to the folder tree widget)
+- No third-party service settings
+
+### 1.9 Handshake ack changes
+
+The `handshake_ack` payload gains per-root metadata:
+
+```python
+# Current
+"roots": [{"name": "Movies", "path": "/mnt/movies", ...}]
+"member_upload": True
+
+# New
+"roots": [{"name": "Movies", "path": "/mnt/movies", "writable": False, "removable": True, ...}]
+# member_upload removed (deprecated, still parsed by old clients)
+```
+
+For backward compatibility with MNP 1.0 peers:
+- A 1.0 client that does not see `writable` on roots falls back to the old model
+  (root with `upload=True` is writable, `member_upload` from the ack controls access)
+- A 1.1 node continues to send `member_upload` as a computed value: `True` if any
+  root is writable, `False` otherwise — so old clients behave sensibly
+- `member_upload` is no longer writable via MNP ops; the node computes it from roots
+
+### 1.10 CLI changes
+
+```
+# Group creation (first root defaults to RW)
+meshbay-node group add <name> --dir <path>                # first root, RW
+meshbay-node group add <name> --dir <path> --read-only    # first root, RO
+
+# Root management
+meshbay-node root add <group> <path> [--name <name>] [--writable] [--removable]
+meshbay-node root remove <group> <name>
+meshbay-node root set <group> <name> --writable           # toggle to RW
+meshbay-node root set <group> <name> --read-only          # toggle to RO
+meshbay-node root set <group> <name> --removable          # mark as removable
+meshbay-node root set <group> <name> --no-removable       # unmark
+meshbay-node root eject <group> <name>                    # safe eject
+meshbay-node root plug <group> <name>                     # re-plug
+meshbay-node root list <group>
+
+# Deprecated (removed with warning)
+--upload-dir   → "use --writable on the target root instead"
+member upload  → "use 'root set --read-only' / 'root set --writable' instead"
+```
+
+### 1.11 HelloWorld proof-of-concept
+
+A minimal app that validates the plugin architecture end to end:
+
+- `static/helloworld-app.js`: renders a greeting and lists files in its configured
+  directory
+- `static/helloworld-app-settings.js`: single-directory picker (via folder tree
+  widget), no other settings
+- Entry in `apps.js` with `key: "helloworld"`, icon, label, Component, Settings
+- `ALLOWED_APPS` extended on the node
+- No dedicated `helloworld.py` — uses the generic `set_app_directory()` function,
+  which is the whole point
+
+The HelloWorld app is **not shipped in production**. It lives in the tree as a
+reference implementation and can be excluded from the build. Its value is proving
+that the plugin mechanism works: zero changes to `group-settings.js`,
+`group-page.js`, `webrtc_server.py` or `ops.py` to add it.
+
+### 1.12 Migration (existing nodes)
+
+A script in `QE/migration/` (not versioned) handles Fedora and Ubuntu nodes:
+
+**node.toml:**
+- `upload = true` → `writable = true`
+- `upload = false` (or absent) → `writable = false`
+- Add `removable = false` to all roots that lack it
+- Remove `upload_dir` from `[[groups]]` blocks (if present)
+
+**roster.db:**
+- If `member_upload = "off"` for a group: set all that group's roots to
+  `writable = false` (the intent was "no uploads")
+- Rename `video_root` → `video_directories` (wrap single value in a list)
+- Rename `audio_root` → `audio_directories` (same)
+- `photo_roots` → `photo_directories` (rename only)
+- Remove `member_upload` rows
+- Add `chat_link_preview = "true"` default for groups with chat enabled
+- Add `chat_directory` for groups that had an upload root (default: the upload
+  root's path)
+
+**Protocol version:**
+- MNP version file bumped to 1.1
+
+**The script is idempotent** — running it twice is safe.
+
+---
+
+## 2. Phase 1 — Root RO/RW model + Shared Directories UI
+
+**Goal:** Change the data model from `upload` to `writable`/`removable`, build the
+shared directories table, restructure the top of Settings and the Create Group
+wizard. Remove the Uploads section. Files always enabled.
+
+**Testable after this phase:** Create a group with RO/RW roots, toggle RW in
+Settings, add/remove roots in the new table, see the Upload button appear/disappear
+in Files based on the current root's writable flag, eject a removable root and verify
+files disappear from all apps without data loss, plug it back and verify files
+reappear, CLI works with new syntax including `root eject/plug`.
+
+### 2.1 Backend changes
+
+| File | Change |
+|---|---|
+| `config.py` | `RootSpec`: add `writable: bool = False`, `removable: bool = False`. Remove `upload` field. `__post_init__` migration: `upload=True` → `writable=True`. Parse new fields from node.toml |
+| `roots.py` | `Root` dataclass: add `writable`, `removable`, `ejected`. Remove `upload`. `available` becomes a computed property: `not self.ejected and self.is_live()`. `_settle_upload_root()` removed. `RootSet.build()`: validate at least one root exists (no RW minimum). `refresh_availability()`: when a `removable` root's path disappears, auto-set `ejected=True` (safety net). Collision checks unchanged |
+| `ops.py` | `add_root()`: accept `writable`, `removable` params. `remove_root()`: refuse removing last root (unchanged). `attach_group()`: first root defaults to `writable=True`. Remove `set_member_upload()`. New: `update_root()` for toggling writable/removable on an existing root (signed op `OP_ROOT_UPDATE`). New: `eject_root()` — sets `ejected=True`, stops watchdog for that root. New: `plug_root()` — checks `is_live()`, sets `ejected=False`, triggers reconciliation |
+| `roster.py` | No schema change (generic key/value). Remove `member_upload` handling from `_apply_group_settings()` |
+| `ui/app.py` | `POST /api/groups/{gid}/roots`: accept `writable`, `removable`. New: `PATCH /api/groups/{gid}/roots/{name}` → `ops.update_root()`. New: `PUT /api/groups/{gid}/roots/{name}/eject` → `ops.eject_root()`. New: `PUT /api/groups/{gid}/roots/{name}/plug` → `ops.plug_root()`. Remove `PUT /api/groups/{gid}/member-upload` |
+| `daemon.py` (CLI) | New `root` subcommand: `add`, `remove`, `set`, `list`. `group add --dir` defaults to `writable=True`. Deprecate `--upload-dir` with warning. Remove `member upload` command |
+| `webrtc_server.py` | Handshake ack: add `writable`/`removable`/`ejected` per root. Compute `member_upload` for backward compat. `_do_file_upload`: check `root.writable` instead of `root.upload` + `member_upload_allowed`. Handle `ROOT_UPDATE`, `ROOT_EJECT`, `ROOT_PLUG` MNP messages. Broadcast root availability changes to all connected peers. `ALLOWED_APPS`: add `"files"` to always-enabled set |
+| `protocol.py` | New message types: `ROOT_UPDATE` / `ROOT_UPDATE_ACK`, `ROOT_EJECT` / `ROOT_EJECT_ACK`, `ROOT_PLUG` / `ROOT_PLUG_ACK`. `ROOT_ADD` gains `writable`, `removable` fields |
+| `indexer.py` | `eject_root()`: stop the watchdog observer for that root, do NOT touch entries. `plug_root()`: restart observer, trigger reconciliation pass. `refresh_availability()`: auto-eject removable roots whose path disappears (set `ejected=True` instead of just flipping `available`) |
+| `handshake.py` | MNP version → 1.1 (minor, additive) |
+
+### 2.2 Frontend changes
+
+| File | Change |
+|---|---|
+| `group-settings.js` | New `SharedDirectoriesTable` component (reusable). Includes eject/plug button per removable root. Move to top of settings (after Invite/Pair). Remove the Uploads toggle section. Remove the old Directories section (root management part — app root pickers stay for now). Calls loopback API for add/remove/update/eject/plug root |
+| `create-group-page.js` | Replace app checkboxes with nothing (Files auto-enabled). Replace directory section with `SharedDirectoriesTable` (same component). First root defaults `writable=true`. Step 2: remove `set enabled_apps` call (Files is automatic) |
+| `files-app.js` | Upload button visibility: check `currentRoot.writable && currentRoot.available`. Upload target: the root currently being browsed. Hide upload affordances on RO roots. Eject/plug button next to each removable root name in root-level view. Ejected roots greyed out with plug icon. Entries from unavailable roots filtered out of all views |
+| `chat-app.js` | Attachment button: disabled if no RW root exists or if the chat directory's root is RO or unavailable. Tooltip explaining why |
+| `group-page.js` | `nodeRoots` state: include `writable`/`removable`/`ejected` from handshake ack. Handle `ROOT_EJECT_ACK`/`ROOT_PLUG_ACK` broadcasts to update root state live. Remove `memberUpload` state. Remove `onUploadPolicy` callback |
+| `video-app.js` | Filter entries: exclude files from unavailable roots |
+| `music-app.js` | Filter entries: exclude files from unavailable roots |
+| `photos-app.js` | Filter entries: exclude files from unavailable roots |
+| `apps.js` | Add `alwaysEnabled: true` to `files` entry |
+| `transport.js` | Parse new root fields from handshake ack |
+
+### 2.3 Localization
+
+New keys in `locales/*.js`:
+- `sharedDirectories`, `sharedDirectoriesHint` ("At least one directory is
+  required...")
+- `readOnly`, `readWrite`, `removableDevice`
+- `uploadNotAvailableRO` (tooltip: "This directory is read-only")
+- `ejectRoot`, `ejectRootConfirm` ("Eject *{name}*? Files from this directory
+  will be temporarily hidden...")
+- `plugRoot`, `plugRootFailed` ("Directory not found. Is the device connected?")
+- `rootEjected` (status label shown on ejected roots)
+- Deprecation: `uploadToggle*` keys can be removed
+
+---
+
+## 3. Phase 2 — App Settings Plugin Architecture + Folder Tree Widget
+
+**Goal:** Split app settings into per-app files, build the folder tree widget,
+restructure Settings with per-app collapsible sections. Normalize server-side
+ops.
+
+**Testable after this phase:** Each app has its own settings section with toggle.
+Folder tree popup works for directory selection. TMDB/MusicBrainz settings are in
+their app sections. Chat has link preview toggle. Videos/Music use multi-directory.
+
+### 3.1 Folder tree widget
+
+| File | Change |
+|---|---|
+| `static/folder-tree.js` (new) | `FolderTreePicker` component. Props: `roots` (with writable/removable), `dirs` (flat list from index), `mode` ("single"/"multi"), `requireWritable` (bool), `selected` (current selection), `onSelect` callback. Renders a modal with tree-view of directories. Builds tree structure from flat `nodeDirs` paths |
+
+**Behavior:**
+- Modal overlay with semi-transparent backdrop, centered panel
+- Root level: each root with folder icon, name, RO/RW badge, removable badge
+- `[+]` / `[-]` toggle to expand/collapse children
+- Directories sorted alphabetically at each level
+- Single mode: clicking a directory selects it (highlight), deselects previous
+- Multi mode: clicking a directory toggles its selection (checkbox visual)
+- `requireWritable=true`: RO roots and all their children are greyed out and
+  unclickable, with a brief explanation at the top of the modal
+- Selected path shown at the bottom of the modal
+- OK (disabled if nothing valid selected) and Cancel buttons
+- Escape key closes
+
+### 3.2 Per-app settings files
+
+| File | Content |
+|---|---|
+| `static/chat-app-settings.js` (new) | `ChatSettings` component. Single-directory picker (folder tree, `requireWritable=true`). Link preview toggle (`ToggleSwitch`). Save button. Validates: selected directory must be on a RW root |
+| `static/video-app-settings.js` (new) | `VideoSettings` component. Multi-directory picker (folder tree). TMDB section: toggle + API key + language (moved from `group-settings.js`). TMDB key prompt: "Sign up on TMDB to generate your API key" with link, no "optional" wording. Save triggers TMDB sweep |
+| `static/music-app-settings.js` (new) | `MusicSettings` component. Multi-directory picker. MusicBrainz section: toggle (moved from `group-settings.js`). Save triggers MusicBrainz sweep |
+| `static/photos-app-settings.js` (new) | `PhotoSettings` component. Multi-directory picker. No third-party settings. Save button |
+| `static/apps.js` | Each `APPS` entry gains `Settings` field imported from the corresponding settings file. `files` has no `Settings` (no per-app config). `files` has `alwaysEnabled: true` (from Phase 1) |
+
+### 3.3 Settings page restructure
+
+| File | Change |
+|---|---|
+| `group-settings.js` | Remove all inlined app settings (TMDB section, MusicBrainz section, app root pickers). Remove the Applications checkbox section. New rendering loop: for each app in `APPS` where `!app.alwaysEnabled && app.Settings`, render a `CollapsibleSection` with: icon + title in header, toggle switch in header, `app.Settings` component inside (visible only when enabled). Section collapsed by default. App toggle triggers signed `OP_APPS_ENABLED` op |
+
+**Final settings layout:**
+
+```
+1. Invite form                    (if admin & invite-only)
+2. Pair operator                  (if nodeAdmin & not paired)
+── App configuration ──
+3. Shared directories             (expanded, SharedDirectoriesTable)
+4. 💬 Chat                        [toggle] (collapsed)
+     └─ Directory picker, Link preview toggle, Save
+5. 🎬 Videos                      [toggle] (collapsed)
+     └─ Directory picker (multi), TMDB settings, Save
+6. 🎵 Music                       [toggle] (collapsed)
+     └─ Directory picker (multi), MusicBrainz settings, Save
+7. 📷 Photos                      [toggle] (collapsed)
+     └─ Directory picker (multi), Save
+8. [Future apps discovered from APPS registry]
+── Node tuning ──
+9. Scan tuning                    (reconcile, debounce)
+── Danger zone ──
+10. Leave / Delete group
+── Identity ──
+11. My devices
+12. Members table
+```
+
+### 3.4 Server-side normalization
+
+| File | Change |
+|---|---|
+| `ops.py` | New generic: `set_app_directory(state, group_id, app_key, path, require_writable=False)` and `set_app_directories(state, group_id, app_key, paths, require_writable=False)`. Both validate path(s) within named roots and check writable if required. Existing `set_video_root` → wrapper calling `set_app_directories("video", ...)`. Same for audio, photo. New: `set_chat_directory(state, group_id, path)` → `set_app_directory("chat", path, require_writable=True)`. New: `set_chat_link_preview(state, group_id, enabled)` |
+| `webrtc_server.py` | Handle new MNP messages: `CHAT_DIRECTORY` / `ACK`, `CHAT_LINK_PREVIEW` / `ACK`. Refactor `VIDEO_ROOT` handler to use generic. Handshake ack: add `chat_directory`, `chat_link_preview` |
+| `protocol.py` | New message types: `CHAT_DIRECTORY`, `CHAT_LINK_PREVIEW` (and acks) |
+| `ui/app.py` | New endpoints: `PUT /api/groups/{gid}/chat-directory`, `PUT /api/groups/{gid}/chat-link-preview`. Generic: `PUT /api/groups/{gid}/app-directories/{app_key}` |
+| `linkpreview.py` | Check `chat_link_preview` setting before unfurling |
+
+### 3.5 Handshake ack additions
+
+```python
+"chat_directory": "/Shared/uploads",
+"chat_link_preview": True,
+"video_directories": ["/Movies", "/Series"],  # replaces video_root (single)
+"audio_directories": ["/Music"],              # replaces audio_root (single)
+"photo_directories": ["/Photos", "/Camera"],  # replaces photo_roots
+```
+
+Old field names (`video_root`, `audio_root`, `photo_roots`) still sent for backward
+compat with MNP 1.0 clients. New clients read the `*_directories` form.
+
+---
+
+## 4. Phase 3 — HelloWorld, CLI polish & Migration
+
+**Goal:** Prove the plugin architecture with a HelloWorld app, finalize CLI changes,
+write and test the migration script.
+
+### 4.1 HelloWorld app
+
+| File | Content |
+|---|---|
+| `static/helloworld-app.js` (new) | Minimal component: renders "Hello, World!" heading + lists files from its configured directory. Uses `entries` from `commonProps`, filtered by the configured path |
+| `static/helloworld-app-settings.js` (new) | `HelloWorldSettings` component: single-directory picker via `FolderTreePicker`, Save button. Uses `set_app_directory("helloworld", path)` on the generic endpoint |
+| `apps.js` | New entry: `{ key: "helloworld", icon: "👋", labelKey: "helloWorld", Component: HelloWorldApp, Settings: HelloWorldSettings }` |
+| `webrtc_server.py` | Add `"helloworld"` to `ALLOWED_APPS` |
+
+**Validation:** enabling HelloWorld in Settings, picking a directory, saving, and
+seeing the file list in the HelloWorld tab — with **zero changes** to
+`group-settings.js`, `group-page.js`, or `ops.py`. If this works, any future app
+can be added the same way.
+
+### 4.2 CLI final polish
+
+- `root` subcommand fully tested: `add`, `remove`, `set`, `list`
+- `group add --upload-dir` prints deprecation warning and maps to `--dir <path>
+  --writable`
+- `member upload` command removed (prints migration guidance)
+- Help text updated to reflect RO/RW model
+- `test_cli_dispatch.py` updated for all new verbs
+
+### 4.3 Migration script
+
+`QE/migration/migrate_groups_v2.sh` (or `.py`) — not versioned, for Fedora/Ubuntu
+nodes only.
+
+**node.toml transformations:**
+```
+upload = true        →  writable = true
+upload = false       →  writable = false
+(no upload field)    →  writable = false
+(add removable = false to every root that lacks it)
+(remove upload_dir lines from [[groups]] blocks)
+```
+
+**roster.db transformations:**
+```sql
+-- Convert member_upload=off to all-RO roots (handled via ops on restart)
+-- Rename app directory keys
+UPDATE group_settings SET key = 'video_directories' WHERE key = 'video_root';
+UPDATE group_settings SET key = 'audio_directories' WHERE key = 'audio_root';
+UPDATE group_settings SET key = 'photo_directories' WHERE key = 'photo_roots';
+-- Wrap single values in JSON arrays for video/audio
+-- Add chat defaults
+INSERT INTO group_settings (group_id, key, value)
+  SELECT group_id, 'chat_link_preview', 'true'
+  FROM group_settings WHERE key = 'enabled_apps' AND value LIKE '%chat%';
+-- Remove member_upload rows
+DELETE FROM group_settings WHERE key = 'member_upload';
+```
+
+**Idempotency:** every transformation is guarded (`IF NOT EXISTS`, check before
+rename, etc.). Safe to run twice.
+
+**Rollback:** the script backs up `node.toml` and `roster.db` before any change.
+
+### 4.4 Windows notes
+
+No migration script needed for Windows (manual setup). Functional non-regression
+testing only:
+- Drive letter roots (`D:\Movies`, `E:\Music`) work with RO/RW
+- Removable flag on USB drives
+- Folder tree widget handles backslash paths
+- Create Group wizard with Windows paths
+
+---
+
+## 5. Risk assessment
+
+| Risk | Mitigation |
+|---|---|
+| Upload regression | Phase 1 is self-contained: test uploads on RW roots, verify refused on RO roots, before touching app settings |
+| Eject data loss | Eject freezes entries (existing `freeze-not-empty` path). Ejected roots are never rescanned. Auto-eject safety net for surprise unplugs on removable roots. Explicit reconciliation (not full rescan) on plug |
+| Indexer race on eject | Watchdog observer is stopped synchronously before `ejected=true` is set. No window where the watchdog sees a missing path and processes deletions |
+| MNP backward compat | Computed `member_upload` in ack for 1.0 clients. New fields additive. Old field names kept alongside new ones |
+| Monolithic `group-settings.js` diff | Phase 2 extracts code into new files; the old code is deleted, not refactored. Clear before/after |
+| Folder tree perf with large indexes | `nodeDirs` is already computed. Tree construction is O(n) on directory count, not file count. Lazy child rendering on expand |
+| Windows path handling | Existing NFC normalization and path handling unchanged. New fields (`writable`, `removable`) are path-independent booleans. Drive letters work as root paths |
+| Migration data loss | Script backs up before changes. Idempotent. Tested on a staging node before production |
+
+---
+
+## 6. Files touched (by phase)
+
+### Phase 1
+```
+packages/meshbay-node/src/meshbay_node/config.py
+packages/meshbay-node/src/meshbay_node/roots.py
+packages/meshbay-node/src/meshbay_node/ops.py
+packages/meshbay-node/src/meshbay_node/roster.py
+packages/meshbay-node/src/meshbay_node/ui/app.py
+packages/meshbay-node/src/meshbay_node/daemon.py
+packages/meshbay-node/src/meshbay_node/transport/webrtc_server.py
+packages/meshbay-common/src/meshbay_common/protocol.py
+packages/meshbay-common/src/meshbay_common/handshake.py
+packages/meshbay-hub/src/meshbay_hub/static/group-settings.js
+packages/meshbay-hub/src/meshbay_hub/static/create-group-page.js
+packages/meshbay-hub/src/meshbay_hub/static/group-page.js
+packages/meshbay-hub/src/meshbay_hub/static/files-app.js
+packages/meshbay-hub/src/meshbay_hub/static/chat-app.js
+packages/meshbay-hub/src/meshbay_hub/static/apps.js
+packages/meshbay-hub/src/meshbay_hub/static/transport.js
+packages/meshbay-node/src/meshbay_node/indexer/indexer.py
+packages/meshbay-hub/src/meshbay_hub/static/video-app.js
+packages/meshbay-hub/src/meshbay_hub/static/music-app.js
+packages/meshbay-hub/src/meshbay_hub/static/photos-app.js
+packages/meshbay-hub/src/meshbay_hub/static/locales/*.js
+```
+
+### Phase 2
+```
+packages/meshbay-hub/src/meshbay_hub/static/folder-tree.js          (new)
+packages/meshbay-hub/src/meshbay_hub/static/chat-app-settings.js    (new)
+packages/meshbay-hub/src/meshbay_hub/static/video-app-settings.js   (new)
+packages/meshbay-hub/src/meshbay_hub/static/music-app-settings.js   (new)
+packages/meshbay-hub/src/meshbay_hub/static/photos-app-settings.js  (new)
+packages/meshbay-hub/src/meshbay_hub/static/group-settings.js       (extract)
+packages/meshbay-hub/src/meshbay_hub/static/apps.js
+packages/meshbay-node/src/meshbay_node/ops.py
+packages/meshbay-node/src/meshbay_node/ui/app.py
+packages/meshbay-node/src/meshbay_node/transport/webrtc_server.py
+packages/meshbay-node/src/meshbay_node/linkpreview.py
+packages/meshbay-common/src/meshbay_common/protocol.py
+packages/meshbay-hub/src/meshbay_hub/static/locales/*.js
+```
+
+### Phase 3
+```
+packages/meshbay-hub/src/meshbay_hub/static/helloworld-app.js          (new)
+packages/meshbay-hub/src/meshbay_hub/static/helloworld-app-settings.js (new)
+packages/meshbay-hub/src/meshbay_hub/static/apps.js
+packages/meshbay-node/src/meshbay_node/transport/webrtc_server.py
+packages/meshbay-node/src/meshbay_node/daemon.py
+tests/test_cli_dispatch.py
+QE/migration/migrate_groups_v2.py                                      (new, not versioned)
+```
+
+---
+
+## 7. Estimated effort
+
+| Phase | Scope | Approx. size |
+|---|---|---|
+| Phase 1 | Data model + shared dirs UI + eject/plug + CLI + remove uploads | ~1800 lines changed/added |
+| Phase 2 | Folder tree + 4 app-settings files + settings restructure + server normalization | ~1800 lines changed/added |
+| Phase 3 | HelloWorld + CLI polish + migration script | ~500 lines |
+
+Each phase is one focused Claude session. Test between phases.