2026-03-21 Session Log

LinguaRAG — Annotation Fixes & Sidebar Refactor

Two sessions: morning fixed language selection bugs and text annotation persistence/resize; evening refactored the sidebar divider system from nested splits to a flat multi-split structure.

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Session 1: Language Selection & Text Annotations

Language selection contamination fix

The learningLang state was persisted to localStorage, which caused a subtle bug: opening a German PDF after a Chinese PDF would show Chinese as the pre-selected language. Fixed by making learningLang pure in-memory state — the server already stores the per-PDF language, so localStorage persistence was unnecessary and harmful.

Also removed the backend auto-detect language feature entirely. The language_detect.py module had a fundamental flaw: Korean hangul characters were classified as Latin script, leading to French misdetection. Simpler and more reliable to let users always choose via the modal.

JSONB codec registration

Text annotation styles were being returned from the database as raw JSON strings instead of parsed objects, causing all style properties (font, bold, italic, etc.) to be undefined in the frontend. Root cause: asyncpg doesn’t automatically parse JSONB columns.

Fixed by registering a JSONB codec (json.loads/json.dumps) on the connection pool at init time. This is a single registration point that benefits all JSONB columns automatically — much cleaner than sprinkling json.dumps calls in individual repository methods (removed 3 such manual calls).

Batch style PATCH on deselect

Previously, every toolbar click (bold, italic, font change) triggered an individual API call. Refactored to a batch approach: toolbar changes update the UI immediately but only send a single PATCH request when the annotation is deselected. Dirty tracking via ref detects whether any style actually changed.

Height resize for text annotations

Added vertical resize capability with bottom edge (↕) and bottom-right corner (⤡) handles. The height field is nullable — null means auto height (content-based, the default), while a number sets a fixed height as a percentage of the container. This maintains backward compatibility with existing annotations.

Other annotation fixes

• Toolbar now syncs to the selected annotation’s actual style (was showing defaults)
• New annotations always start with DEFAULT_TEXT_STYLE (not the last-used style)
• Fixed event bubbling where clicking in text mode would deselect the just-created annotation
• Deferred annotation layer rendering until PDF page render completes (prevents flash)
• Fixed alignment icon SVGs (left/center/right were visually identical)

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Session 2: Sidebar Multi-Split Refactor

The problem with nested splits

The sidebar had 4 sections (Bookmarks, Chats, Folders, Vocabulary) arranged in a nested percentage-based split:

Outer split (top half / bottom half)
  ├─ Top: Bookmarks (fixed px) + Chats (flex)
  └─ Bottom: Folders (flex) + Vocabulary (fixed px)

This caused two issues:

1. Divider coupling: Dragging the Chats↔Folders divider would shift the Bookmarks↔Chats and Folders↔Vocab dividers too, because resizing the outer container proportionally repositions the inner percentage-based dividers.
2. Refresh jump: On page load, the server rendered the guest layout (Bookmarks at auto height), then auth resolved and switched to the logged-in layout (Bookmarks at 15%) — causing a visible layout jump.

The flat multi-split solution

Replaced the entire structure with a single useMultiSplit hook that manages all 4 sections at the same level:

Container (flat)
  ├─ Bookmarks  (pcts[0]%)
  ├─ divider 0  → adjusts pcts[0] and pcts[1] only
  ├─ Chats      (pcts[1]%)
  ├─ divider 1  → adjusts pcts[1] and pcts[2] only
  ├─ Folders    (pcts[2]%)
  ├─ divider 2  → adjusts pcts[2] and pcts[3] only
  └─ Vocabulary (pcts[3]%)

Each divider only modifies its two adjacent percentage values. Moving the Chats↔Folders divider changes pcts[1] and pcts[2] — Bookmarks and Vocabulary percentages stay fixed.

Unified guest/logged-in layout

Both guest and logged-in users now render the same multiSplit container. For guests, dividers are static (non-draggable thin lines) and section content shows login prompts. This eliminates the auth-transition layout jump since the DOM structure doesn’t change.

Divider styling: thin h-px gray line by default, thickens to h-1 blue on hover/drag for easy grabbing.

Key Decisions

Decision	Reasoning
Flat multi-split over nested	Nested percentage splits cause proportional divider movement when outer container resizes
Unified guest/logged-in layout	Prevents layout jump on auth state transition by keeping the same DOM structure
JSONB codec at pool level	Single registration vs. per-query manual parsing; all JSONB columns benefit automatically
Batch style PATCH on deselect	Reduces N API calls (per toolbar click) to 1 (on deselect); dirty tracking via ref
Pure in-memory learningLang	Server stores per-PDF language; localStorage caused cross-PDF contamination

Next

• Test text annotation height resize with existing annotations after refresh
• Greeting redesign with pre-generated summary + suggested question buttons
• Flashcard batch generation with Haiku
• Vercel unpause + production deployment