expand B7 with implementation plan for Apple Silicon

Current-WiP.md

@@ -18,7 +18,12 @@ All 15 tasks are done. Final commit: `f0689ac feat: Roadmap N — AMQP cluster n
 - HTTPS / reverse proxy (Caddy)
 - Conversation search/filter and export tooling
 - B6 — Waterfall direction toggle — add a setting to flip message order between top-down (newest at top, waterfall) and bottom-up (newest at bottom, standard chat). Needs `localStorage` persistence and a UI toggle (maybe in settings modal or topbar).
-- B7 — Apple Silicon worker support — document/validate running the node agent + llama-server on macOS with M-series GPUs (Metal backend). May need changes to hardware probing, GPU stats, and node registration.
+- **B7 — Apple Silicon worker support** — no Apple hardware needed for implementation; llama.cpp Metal backend exposes the same OpenAI-compat API. Changes:
+  - `gpu.py` — add `get_gpu_stats_macos()` path using `system_profiler SPDisplaysDataType` for VRAM, `sysctl hw.memsize` for unified memory
+  - `hardware.py` — `platform.system() == "Darwin"` branch skips `rocm-smi`, calls macOS VRAM probe instead
+  - `node_agent/agent.py` — detect macOS, register with `platform: darwin, backend: metal`
+  - `routers/models.py` — `get_gpu_stats()` dispatch to Metal stats on macOS
+  - Tests — add test fixture mocking a darwin worker registration + ping/pong; coordinator treats it identically to CUDA/ROCm workers
 - Keyboard shortcuts, retry button, source-link polish
 
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