Add backlink

ARCHITECTURE.md

@@ -170,6 +170,58 @@ User types in editor → CodeMirror EditorView.updateListener
                                    └─ HTMX updates file tree automatically
 ```
 
+### 6. Creating Links Between Notes (Internal Links)
+
+```
+User types /ilink → SlashCommands detects slash + query
+                   │
+                   ├─ Filters commands by query
+                   └─ Shows command palette
+                      │
+                      └─ User selects "ilink" → SlashCommands.openLinkInserter()
+                                               │
+                                               ├─ Saves current cursor position
+                                               └─ Opens LinkInserter modal
+                                                  │
+User types query → LinkInserter searches
+                   │
+                   ├─ Debounce 200ms
+                   └─ fetch('/api/search?query=...')
+                      │
+                      ├─ Go Server queries indexer
+                      ├─ Returns HTML results
+                      └─ LinkInserter parses HTML
+                         │
+                         ├─ Extracts title, path, tags
+                         ├─ Renders in modal
+                         └─ Updates keyboard selection
+                            │
+User selects note → LinkInserter.selectResult()
+(Enter/click)       │
+                    ├─ Calls callback with {title, path}
+                    └─ SlashCommands.openLinkInserter callback
+                       │
+                       ├─ Builds HTML with HTMX: <a href="#" hx-get="/api/notes/path">title</a>
+                       ├─ Uses CodeMirror transaction
+                       ├─ Replaces /ilink with HTML link
+                       ├─ Positions cursor after link
+                       └─ Closes modal
+                          │
+Preview Rendering → marked.js parses Markdown (including inline HTML)
+                    │
+                    ├─ DOMPurify sanitizes (allows hx-* attributes)
+                    ├─ htmx.process() activates HTMX on links
+                    └─ Links become clickable → load note via HTMX
+```
+
+**Key Design Decisions**:
+- **No new backend code**: Reuses existing `/api/search` endpoint for search, `/api/notes/` for navigation
+- **Database-free**: Leverages in-memory indexer for speed
+- **Consistent UX**: Modal design matches SearchModal styling
+- **Clickable links**: HTML with HTMX attributes, rendered directly by marked.js
+- **HTMX integration**: Links use `hx-get` to load notes without page reload
+- **Keyboard-first**: Full keyboard navigation without mouse
+
 ## Frontend Architecture
 
 ### Build Process (Vite)
@@ -224,6 +276,17 @@ Executed in browser → Initializes components
 - Result highlighting
 - Uses HTMX search API
 
+**link-inserter.js**
+- LinkInserter class for internal note linking
+- Modal search interface for `/ilink` command
+- Fuzzy search across notes
+- Keyboard navigation (↑/↓/Enter/Esc)
+- Integration with SlashCommands
+- Uses HTMX search API for consistency
+- Inserts Markdown links into editor
+
+**Note**: `/link` command inserts standard Markdown template `[texte](url)` for external links
+
 **ui.js**
 - Sidebar toggle (mobile/desktop)
 - Simple utility functions