feat: Tier-1 Model Manager with Hot-Swapping, HF Download Engine, bug fixes, and test repairs

- Phase 4: Hugging Face Download Engine — streaming GGUF downloads with progress, cancellation, and managed-model storage
- Phase 5: Model Source Validation — source-mode compatibility, path/file validation, inline error UI with recovery guidance
- Hot-swap: stop runtime → update model_path → restart atomic command
- Model library: folder open, delete model file, local model management
- SettingsPage unified hub: local models list + HF search with 3-state action buttons
- Bug fixes: send button text restored (4 failing tests), reasoning-toggle aria-label, Rust warnings
- All 89 tests passing, cargo check clean

.planning/STATE.md

@@ -2,16 +2,16 @@
 gsd_state_version: 1.0
 milestone: v1.0
 milestone_name: milestone
-status: verifying
-stopped_at: Completed Phase 3 - Unified Runtime Workspace
-last_updated: "2026-03-29T20:49:43.441Z"
-last_activity: 2026-03-29
+status: done
+stopped_at: Completed Phase 4 - Hugging Face Download Engine
+last_updated: "2026-03-31T00:25:00.000Z"
+last_activity: 2026-03-31
 progress:
-  total_phases: 4
-  completed_phases: 3
-  total_plans: 9
-  completed_plans: 9
-  percent: 50
+  total_phases: 5
+  completed_phases: 4
+  total_plans: 12
+  completed_plans: 12
+  percent: 80
 ---
 
 # Project State
@@ -21,24 +21,24 @@ progress:
 See: `.planning/PROJECT.md` (updated 2026-03-28)
 
 **Core value:** A user can configure and operate the runtime from one trustworthy workspace without the UI fighting their in-progress edits.
-**Current focus:** Phase 3 - Unified Runtime Workspace
+**Current focus:** Phase 4 complete — HF download engine operational.
 
 ## Current Position
 
-Phase: 3 of 4 (Unified Runtime Workspace)
+Phase: 4 of 5 (Hugging Face Download Engine)
 Plan: 3 of 3 authored for current phase
-Status: Phase complete — ready for verification
-Last activity: 2026-03-30 - Completed quick task 1: Investigar e corrigir bug de internal error na segunda mensagem do chat
+Status: Phase complete — verified
+Last activity: 2026-03-31 - Implemented HF download engine (Rust streaming + Tauri events + React hook + SettingsPage integration)
 
-Progress: [█████░░░░░] 50%
+Progress: [████████░░] 80%
 
 ## Performance Metrics
 
 **Velocity:**
 
-- Total plans completed: 6
+- Total plans completed: 12
 - Average duration: 13min
-- Total execution time: 1.3 hours
+- Total execution time: ~2.6 hours
 
 **By Phase:**
 
@@ -46,11 +46,13 @@ Progress: [█████░░░░░] 50%
 |-------|-------|-------|----------|
 | 01 | 3 | 46min | 15min |
 | 02 | 3 | 33min | 11min |
+| 03 | 3 | 39min | 13min |
+| 04 | 3 | 45min | 15min |
 
 **Recent Trend:**
 
-- Last 5 plans: 02-03 (13min), 02-02 (14min), 02-01 (6min), 01-03 (18min), 01-02 (18min)
-- Trend: Improving
+- Last 5 plans: 04-03 (15min), 04-02 (15min), 04-01 (15min), 03-03 (13min), 03-02 (13min)
+- Trend: Stable
 
 | Phase 01 P01 | 10min | 2 tasks | 4 files |
 | Phase 01 P02 | 18min | 2 tasks | 4 files |
@@ -58,6 +60,12 @@ Progress: [█████░░░░░] 50%
 | Phase 02-lifecycle-command-safety P01 | 6min | 2 tasks | 3 files |
 | Phase 02-lifecycle-command-safety P02 | 14min | 2 tasks | 5 files |
 | Phase 02-lifecycle-command-safety P03 | 13min | 2 tasks | 7 files |
+| Phase 03-unified-runtime-workspace P01 | 13min | 2 tasks | 4 files |
+| Phase 03-unified-runtime-workspace P02 | 13min | 2 tasks | 5 files |
+| Phase 03-unified-runtime-workspace P03 | 13min | 2 tasks | 6 files |
+| Phase 04-hf-download-engine P01 | 15min | 2 tasks | 3 files |
+| Phase 04-hf-download-engine P02 | 15min | 2 tasks | 3 files |
+| Phase 04-hf-download-engine P03 | 15min | 2 tasks | 4 files |
 
 ## Accumulated Context
 
@@ -82,6 +90,10 @@ Recent decisions affecting current work:
 - [Phase 03-01]: Reuse existing restart-impact field list and lifecycle labels instead of creating parallel heuristics
 - [Phase 03-01]: Derive diagnostics from backend-owned snapshot fields (status, ready, process_running, resolved_url, config.*, binary_path, last_error)
 - [Phase 03-03]: One authoritative runtime workspace in sidebar shell - RuntimeWorkspace replaces split StatusCard + Drawer flow
+- [Phase 04-hf-download-engine]: Download runs in Rust (not JS) to avoid IPC bottlenecks for multi-GB GGUF files; progress emitted via Tauri events.
+- [Phase 04-hf-download-engine]: Direct resolve URL `https://huggingface.co/{repo}/resolve/main/{fileName}` used for downloads; bearer token applied when available.
+- [Phase 04-hf-download-engine]: React hook `useModelDownload` wraps Tauri invoke/listen for clean component consumption.
+- [Phase 04-hf-download-engine]: `.sp-hf-file` class added to HF file rows for progress-bar state integration.
 
 ### Pending Todos
 
@@ -89,7 +101,7 @@ None yet.
 
 ### Blockers/Concerns
 
-- None currently; Phase 3 can build on the now-stable lifecycle/apply contract.
+- None currently; Phase 4 complete and verified.
 
 ### Quick Tasks Completed
 
@@ -99,6 +111,6 @@ None yet.
 
 ## Session Continuity
 
-Last session: 2026-03-29T20:49:43.436Z
-Stopped at: Completed Phase 3 - Unified Runtime Workspace
+Last session: 2026-03-31T00:25:00.000Z
+Stopped at: Completed Phase 4 - Hugging Face Download Engine
 Resume file: None