feat: real-time transcript streaming with TanStack Query

[lucasheriques]

Summary

Refactored Notetaker from Dexie local-first to TanStack Query backend-first architecture with smart caching and real-time transcript streaming.

This PR builds on #1 (Recall SDK integration) to add live transcript display with intelligent backend sync.

Architecture Changes

• ❌ Removed Dexie (IndexedDB) dependency
• ✅ Migrated to TanStack Query for server state management
• ✅ Backend-first with PostHog as source of truth
• ✅ Local buffering with batched uploads (10 segments OR 10 seconds)

Key Features

• ⚡ Real-time transcript segments from Recall.ai AssemblyAI stream
• 📊 Smart polling: 2s during active recording, 10s for ready recordings
• 🔄 Local buffer prevents duplicate uploads with timestamp tracking
• 🎯 Optimistic UI updates with "pending upload" badge
• 🔁 Automatic query invalidation and cache management
• 📏 Transcript view limited to 60vh (leaves room for notes/action items)
• 🔄 Auto-scroll with manual override detection
• 🔄 Retry button for failed uploads

Query Keys

To avoid collision with legacy Recordings feature:

• notetaker-recordings - List of all recordings
• notetaker-recording - Individual recording details
• notetaker-transcript - Transcript segments for a recording

Files Added

• src/renderer/features/notetaker/hooks/useRecordings.ts - TanStack Query hooks for recordings
• src/renderer/features/notetaker/hooks/useTranscript.ts - Local buffering + batched upload logic
• src/renderer/features/notetaker/components/LiveTranscriptView.tsx - Real-time transcript UI

Files Removed

• src/renderer/features/notetaker/stores/notetakerStore.ts - Replaced by TanStack Query
• src/renderer/services/db.ts - Dexie schema (no longer needed)
• src/renderer/services/transcriptSync.ts - Integrated into hooks

Dependencies Removed

• dexie
• dexie-react-hooks

Data Flow

IPC Events (Real-time) → Local Buffer (React State)
                            ↓
                    Batch Upload (10 segments / 10s)
                            ↓
                    PostHog Backend (Source of Truth)
                            ↓
                    TanStack Query Cache (Auto-polling)
                            ↓
                        UI Display (60vh max height)

Test Plan

• Start a Zoom/Meet/Teams meeting
• Verify recording starts automatically
• Verify transcript segments appear in real-time
• Verify auto-scroll works
• Manually scroll up and verify auto-scroll disables
• Scroll to bottom and verify auto-scroll re-enables
• Verify batched uploads happen every 10 segments
• Verify pending upload badge shows during buffering
• End meeting and verify final upload happens
• Verify no mystery recordings from legacy feature

[lucasheriques]

• feat: add AI task extraction for notetaker recordings #68
• feat: real-time transcript streaming with TanStack Query #67 👈 (View in Graphite)
• feat: integrate Recall SDK for meeting detection and recording #65 : 1 other dependent PR (#73 )
• main

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