docs: add design spec for public note sharing (#7)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
2026-03-20 21:03:44 +01:00
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+# Public Note Sharing — Design Spec
+
+**Issue**: [#7 — Public links and shared notes](https://github.com/bretzel-app/crumbs/issues/7)
+**Date**: 2026-03-20
+
+## Overview
+
+Allow sharing individual notes via a public URL that anyone can view without authentication. Read-only sharing via unguessable tokens. Integrates into the existing ShareDialog alongside collaborator management.
+
+## Decisions
+
+| Decision | Choice | Rationale |
+|---|---|---|
+| Share UI location | Inside existing ShareDialog | One "Share" entry point for all sharing (public + collaborators) |
+| Expiry | Deferred to future version | Simpler v1; active/revoked toggle only |
+| Rate limiting | In-memory per-IP | Lightweight, resets on restart; token entropy handles enumeration |
+| Architecture | Separated shares-service | Follows collaborators-service pattern; clean module boundary |
+| Sharing icon | Globe (public) or Users (collaborators) | Single icon slot; tooltip shows combined sharing state |
+
+## Schema
+
+New `sharedNotes` table in `src/lib/server/db/schema.ts`:
+
+```typescript
+export const sharedNotes = sqliteTable('shared_notes', {
+  noteId: text('note_id').primaryKey().references(() => notes.id, { onDelete: 'cascade' }),
+  token: text('token').notNull().unique(),
+  createdAt: integer('created_at', { mode: 'timestamp' }).notNull(),
+  expiresAt: integer('expires_at', { mode: 'timestamp' }), // NULL = no expiry, reserved for future use
+});
+```
+
+- `noteId` as primary key — one share per note, no separate `id` needed
+- `integer` timestamps with `mode: 'timestamp'` — matches all other tables in the schema
+- `createdAt` set in service layer (`new Date()`), not via SQL default
+- CASCADE delete — deleting the note removes the share
+- Token: `nanoid(21)` — ~128 bits of entropy
+- No update to `deleteUser()` needed — shares cascade through notes (foreign keys enabled via `PRAGMA foreign_keys = ON` in db connection)
+
+## Types
+
+Add to `src/lib/types/index.ts`:
+
+```typescript
+export interface NoteShare {
+  noteId: string;
+  token: string;
+  createdAt: Date;
+  expiresAt: Date | null;
+}
+```
+
+Extend the `Note` interface:
+
+```typescript
+export interface Note {
+  // ...existing fields
+  shareToken?: string; // populated during hydration if a public share exists
+}
+```
+
+## Service Layer
+
+New file: `src/lib/server/shares-service.ts`
+
+| Function | Params | Returns | Description |
+|---|---|---|---|
+| `createShare` | `db, noteId, userId` | `{ token }` | Verify ownership, generate nanoid(21), insert row, return token. If share already exists, return existing token. |
+| `revokeShare` | `db, noteId, userId` | `void` | Verify ownership, delete share row |
+| `getShareByNoteId` | `db, noteId` | `NoteShare \| null` | Return share if exists (for ShareDialog) |
+| `getSharedNote` | `db, token` | `SharedNoteData \| null` | Public — fetch note by token, return null if trashed or not found |
+| `fetchSharesForNotes` | `db, noteIds` | `Map<string, string>` | Batch fetch — returns Map of noteId → token for hydration (only token needed for NoteCard indicator) |
+
+`SharedNoteData` type (returned to public viewers):
+
+```typescript
+interface SharedNoteData {
+  title: string;
+  content: string;
+  checklistMode: boolean;
+  color: NoteColor;
+  attachments: Attachment[];
+  createdAt: Date;
+  updatedAt: Date;
+}
+```
+
+## API Endpoints
+
+### `POST /api/notes/[id]/share`
+
+- **Auth**: Required (owner only)
+- **Body**: None
+- **Response**: `{ token: string, url: string }`
+- **Behavior**: Creates share or returns existing one. URL constructed from request origin + `/s/${token}`
+
+### `DELETE /api/notes/[id]/share`
+
+- **Auth**: Required (owner only)
+- **Response**: `204 No Content`
+- **Behavior**: Deletes share row. Link immediately returns 404.
+
+### `GET /api/shared/[token]`
+
+- **Auth**: None (public)
+- **Rate limit**: 60 requests/min per IP (in-memory)
+- **Response**: `SharedNoteData` JSON
+- **Error cases**:
+  - Invalid/unknown token → 404
+  - Note is trashed → 404
+  - Rate limited → 429
+
+### `GET /api/shared/[token]/attachment/[attachmentId]`
+
+- **Auth**: None (public)
+- **Rate limit**: Same as above
+- **Response**: Image binary (proxied from attachment storage)
+- **Behavior**: Verify attachment belongs to the shared note, then serve
+
+## Routes
+
+```
+src/routes/
+  (share)/
+    +layout.svelte       # Minimal layout: parchment bg, centered, no app chrome
+    s/[token]/
+      +page.server.ts    # Load shared note by token via shares-service
+      +page.svelte       # Read-only note renderer
+```
+
+### Auth Middleware
+
+Add `/s/` and `/api/shared` to `PUBLIC_PATHS` in `src/hooks.server.ts`. Both are needed — `/s/` for the public page route, `/api/shared` for the public API endpoints.
+
+### Public Page Design
+
+- Parchment background (`--bg-base`)
+- Centered content card (`--bg-surface`, `--border-subtle`, `--card-shadow`)
+- Note title in JetBrains Mono
+- Rendered markdown content or checklist (read-only)
+- Inline images from attachments
+- No tags, no edit controls, no sidebar, no navigation
+- Footer: "POWERED BY CRUMBS" in Press Start 2P pixel font, links to project
+
+## UI Components
+
+### ShareDialog Changes
+
+Add a "Public link" section **above** the existing collaborators section:
+
+**Inactive state:**
+- Globe icon + "Public link" label + toggle switch (off)
+- Subtitle: "Anyone with the link can view this note (read-only)"
+
+**Active state:**
+- Globe icon + "Public link" label + toggle switch (on, gold)
+- URL input (readonly) + "Copy" button
+- Subtitle: "Toggle off to revoke access. The link will return a 404."
+- Border highlight in `--primary` gold
+
+Toggle on → calls `POST /api/notes/[id]/share`, displays URL
+Toggle off → calls `DELETE /api/notes/[id]/share`, hides URL
+Copy button → clipboard API, brief "Copied!" feedback
+
+### NoteCard Share Indicator
+
+Single icon slot in top-right of NoteCard (replaces showing both icons):
+
+| State | Icon | Color |
+|---|---|---|
+| Public link active | `Globe` (Lucide) | `--primary` gold |
+| Collaborators only | `Users` (Lucide) | `--text-muted` |
+| Both | `Globe` (Lucide) | `--primary` gold |
+| Neither | No icon | — |
+
+**Hover tooltip** shows combined sharing info regardless of which icon is displayed:
+- "Shared publicly via link" (if public share exists)
+- "Shared with N collaborator(s)" (if collaborators exist)
+- Both lines if both exist
+
+### NoteEditor Share Button
+
+Existing Share button behavior unchanged. The Globe/Users icon logic from NoteCard also applies to the editor toolbar button to indicate current sharing state.
+
+## Rate Limiting
+
+New file: `src/lib/server/ip-rate-limit.ts` — separate from the existing DB-backed `rate-limit.ts` (which is login-specific).
+
+```typescript
+// In-memory store: Map<IP, { count: number, windowStart: number }>
+// 60 requests per minute per IP
+// Applied to GET /api/shared/[token] and GET /api/shared/[token]/attachment/[id]
+```
+
+Resets on server restart. No database table needed.
+
+## Hydration
+
+`hydrateNotes()` in `notes-service.ts` must be updated to call `fetchSharesForNotes()` and populate `shareToken` on each note. This follows the existing pattern where `hydrateNotes` already batch-fetches tags, attachments, and collaborators.
+
+## Security
+
+- Tokens are unguessable: nanoid(21) = ~128 bits of entropy
+- `/s/` and `/api/shared` routes bypass auth middleware — only these prefixes
+- Trashed notes return 404 even if share token is valid
+- Only note owners can create/revoke shares — collaborators cannot
+- No user information exposed on public page (no username, no email, no tags)
+- Rate limiting prevents brute-force enumeration
+- Attachments served through share-specific route (validates attachment belongs to shared note)
+
+## Out of Scope (v1)
+
+- Expiry dates / auto-expire
+- Password-protected shares
+- Edit access through share links
+- Share analytics / view counts
+- Email notifications for share events
+- E2EE interaction (no E2EE exists)
+
+## Acceptance Criteria
+
+- [ ] Share toggle in ShareDialog creates/revokes public link
+- [ ] Unique nanoid(21) token generated per shared note
+- [ ] Public `/s/[token]` route renders note without auth
+- [ ] Copy link to clipboard with feedback
+- [ ] Revoke share → link returns 404
+- [ ] Globe indicator on NoteCard for publicly shared notes
+- [ ] Combined tooltip showing all sharing state
+- [ ] Trashed notes return 404 even if shared
+- [ ] Minimal, parchment-styled public page with "Powered by Crumbs"
+- [ ] In-memory rate limiting on public endpoints
+- [ ] Attachments accessible on public page