feat(gui): Toast notification system for mapping fires (#487)

CHANGELOG.md

@@ -13,6 +13,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 - **GUI**: EventFilter Fired toggle and quick filters (#486). Independent "⚡ Fired" toggle for mapping_fired event visibility, quick filter buttons (All/Raw Only/Fired Only), and state consistency guard preventing contradictory filter states.
+- **GUI**: Toast notification system for mapping fires (#487, ADR-014 Phase 4). Transient workspace overlays showing trigger→action summaries with auto-dismiss (3s), hover-pause, error persistence, coalescence for continuous controls, max 5 visible. `toastsEnabled`/`toastsContinuous` settings gate toast emission.
 - **GUI v2 Phase 1 — Layout Shell**: Rewrote `App.svelte` from router-based 8-view layout to three-zone unified workspace (Chat | Workspace | Events). Created `ChatPanel`, `WorkspacePanel`, `EventStreamPanel` panel components. Created `TitleBar` with device/profile dropdowns and settings gear. Created `workspace.js` store (9 workspace views, config diff/MIDI learn action routing) and `events.js` store (ring buffer, filters, app-level Tauri event listener). Added `theme.css` with full navy/indigo CSS variable palette. Updated `StatusBar` with CSS variables and dynamic version. Deleted old `views/` directory and `Sidebar.svelte`.
 - **GUI v2 Phase 2 — Config Approval Flow**: Replaced modal-based config approval with workspace-integrated diff view. Created `ConfigDiffView` (pending change review with approve/edit/reject buttons, expiration countdown, change descriptions, diff preview), `MappingStateView` (mode tabs + mapping list, compact mode), `MappingRow` (trigger→action display with colored event-type dots and NEW/UPD badges), `DiffBlock` (simplified diff renderer). Created `diff-helpers.ts` utility with `formatTriggerText`, `formatActionText`, `getTriggerDotColor`. Wired LLM plan creation to workspace via `showConfigDiff()`. Non-mapping workspace views show compact mapping list below. **Spec deviation**: Reused existing `llm_apply_plan`/`llm_reject_plan` Rust commands instead of adding 3 new backend commands (same functionality, avoids duplication).
 - **GUI v2 Phase 3 — MIDI Learn Refinement**: Replaced MIDI Learn modal capture with workspace-integrated refinement card. Created `RefinementCard` (interpretation chips, editable parameter fields, advanced velocity range slider, confirm/relearn/cancel actions), `AlternativeChips` (interpretation selector), `RangeSlider` (dual-thumb velocity range slider), `MidiLearnRefinement` (workspace view container). Created `refinement-helpers.ts` utility with `getAlternativeInterpretations`, `getParameterFields`, `buildTriggerFromParams`. Added `Refining` state to `LearnSessionState` in Rust backend. Wired event selection to workspace refinement via `showMidiLearnRefinement()`. **Spec deviation**: Refinement logic implemented as pure TypeScript functions instead of new Rust Tauri commands — event data from existing `stop_midi_learn` response is sufficient, avoids unnecessary IPC round-trips.

conductor-gui/ui/src/App.test.ts

@@ -108,6 +108,8 @@ vi.mock('$lib/stores/events.js', async () => {
     initEventListener: vi.fn(() => Promise.resolve(() => {})),
     restartEventMonitoring: vi.fn(() => Promise.resolve(() => {})),
     eventFiredFilter: writable(true),
+    toastsEnabled: writable(true),
+    toastsContinuous: writable(false),
     eventMonitorStatus: writable('connecting'),
     eventStreamPanelVisible: writable(true),
   };

conductor-gui/ui/src/lib/components/DeviceStatusPills.test.ts

@@ -40,6 +40,8 @@ vi.mock('$lib/stores/events.js', async () => {
     eventChannelFilter: writable('all'),
     eventDeviceFilter: mockEventDeviceFilter,
     eventFiredFilter: writable(true),
+    toastsEnabled: writable(true),
+    toastsContinuous: writable(false),
     eventStreamVisible: writable(true),
     learnSessionActive: writable(false),
     autoScroll: writable(true),

conductor-gui/ui/src/lib/components/EventFilter.test.ts

@@ -24,6 +24,8 @@ vi.mock('$lib/stores/events.js', async () => {
     eventFiredFilter: mockEventFiredFilter,
     eventChannelFilter: writable('all'),
     eventDeviceFilter: writable('all'),
+    toastsEnabled: writable(true),
+    toastsContinuous: writable(false),
     eventStreamVisible: writable(true),
     learnSessionActive: writable(false),
     autoScroll: writable(true),