Phase 3 — Client feature slices

[rsml]

Part of the demo-quality refactor tracked in docs/plans/refactor/. Branch phase-3-client-slices. Depends on Phase 1, and rebases on the Phase 2 foundations PR.

Objective

Make the client feature sliced with exactly one typed API client. Today there are 84 raw fetch sites and a 2,244 line App.tsx. After this phase, components render and hooks hold logic.

Contents

• One typed api/ client consuming the shared contract types, with zero raw fetch() outside it
• Feature slices for library, reader, creation, audiobook, and settings
• App.tsx down to roughly 150 lines of providers and routes
• The 20 plus dialog useState calls consolidated into a single dialog state machine, with reducer tests landing first
• Hooks extraction, store.ts split into a store/ folder, named timing constants, and accessibility fixes

Gate

• Grep gates pass, meaning no fetch( outside client/api/
• File size caps respected
• Persisted Redux state is byte identical before and after, so existing users lose nothing
• Manual full pass through the app
• Tests, typecheck, and lint all green

[rsml]

Landed in #48, merged to master as 3ed049e with CI green on macos-14.

Fifty one commits, rebase merged so the test-first ordering stays visible in history.

Gate	Before	After
fetch or EventSource outside client/api/	84	0
App.tsx	2245 lines	117
ReaderPage.tsx	1083 lines	362
interface Book declarations	7	0
tests	286	458
buttons with no accessible name	42	0

Behaviour preservation was measured rather than asserted. The reader renders 0 pixels different from master out of 1,296,000. The library differs by 18 pixels against a control noise floor of 30, so its difference from master is smaller than the branch's own run to run variance, which is what the deliberately random texture overlay allows. Persisted state is byte identical across the store split on 125 KB of real data, and rehydration through the Electron IPC path is proven by a controlled experiment, a seeded reading position opens chapter 1 where the server fallback opens chapter 3.

Five sanctioned behaviour changes are documented in the PR body, none on a success path. LibraryPage.tsx is deliberately left at 1190 lines, since roughly 760 of those are drag and drop, filtering, sorting and grid markup that no Phase 3 task owns. It is recorded as a capped Phase 5 candidate.