Merge PR #813

docs/denoise.md

@@ -121,6 +121,51 @@ LC_DENOISE_MODEL=<model.onnx> LC_DENOISE_RAW=<corpus/raw> cargo test --release -
 LC_DENOISE_MODEL=<model.onnx> LC_DENOISE_RAW=<corpus/raw> cargo test --release -p lightcraft-engine --features rawnind-model --test denoise_real -- --ignored --nocapture
 ```
 
+## Another computer's graphics card
+
+A laptop can hand tiles to a desktop with a bigger graphics card over a LAN or a VPN. The server runs the installed,
+selected model the way the app does (the card when it can run it, checked against the CPU first; else the CPU):
+
+```text
+export LIGHTCRAFT_DENOISE_TOKEN='a long random string, at least 16 characters'
+lightcraft-cli denoise-serve --listen 100.101.102.103:7990          # e.g. the machine's Tailscale address
+```
+
+On the laptop, before LightCraft starts:
+
+```text
+export LIGHTCRAFT_DENOISE_URL=100.101.102.103:7990
+export LIGHTCRAFT_DENOISE_TOKEN='…the same token…'
+```
+
+When the laptop first uses the model it greets the server and times a check tile there and back. If that is faster
+than a tile on the laptop (its graphics card, or its processor with the tiles it runs at once), the server's slots
+(four tiles in flight) are added to the laptop's own: a tile goes to the server when one of its slots is free and runs
+locally otherwise. If it is slower, nothing is sent, so a photo never waits for the slower machine:
+`denoise.status` → `device.remote.state` is `slower`, with both times (`remoteMs`, `localMs`). Measured with
+RawNIND: an Apple M3 laptop does a tile in 116 ms, an RTX 3060 Ti reached over Tailscale 345 ms there and back,
+so that laptop keeps its tiles; one without a fast card hands them over. A tile the server fails runs locally; after
+three failures the server is no longer used for that model. Both ends must
+run the same model file: the client compares the manifest's SHA-256 (or the file's) when it first greets the server,
+and the server checks it again for every tile. `denoise.status` → `device.remote` reports the server's address, its
+device and whether it is used, or why not.
+
+**The protocol is not encrypted.** Listen on a VPN address (Tailscale, WireGuard) or a LAN, or bind every interface
+behind a firewall rule that admits only the VPN; never expose the port to the internet. Requests carry the shared
+token (compared in constant time); the server refuses other models, other tile sizes, oversized headers and payloads
+(also ones that inflate past their tile) and caps concurrent connections (`--max-connections`, default 8).
+
+Protocol version 1 (`crates/denoise/src/remote.rs`): one JSON line per message, then a payload of `bytes` bytes —
+the tile's samples as little-endian half floats, byte-shuffled (low bytes, then high bytes) and deflated:
+
+```text
+→ {"v":1,"token":"…","op":"hello"}
+← {"ok":true,"v":1,"device":"GPU: …","model":{"id":"…","version":"…","sha256":"…"},"tile":T}
+→ {"v":1,"token":"…","op":"run","model":"<sha256>","tile":T,"bytes":N}   + N bytes (4 planes of T × T cells)
+← {"ok":true,"tile":T,"bytes":N}                                        + N bytes (3 planes of 2T × 2T pixels)
+← {"ok":false,"error":"…"}
+```
+
 ## Commands and limits
 
 UI, CLI, control channel and MCP dispatch `denoise.toggle`, `denoise.settings`,

docs/parity-checklist.md

@@ -205,7 +205,7 @@ differences and missing bindings are in [ui-parity.md](ui-parity.md#shortcuts).
 | LR-EDIT-DETAIL-SHARPEN | Sharpening | P0 | ✅ | `ctl:detail.sharpenAmount`, `ctl:detail.sharpenRadius`, `ctl:detail.sharpenDetail`, `ctl:detail.sharpenMasking` | no Alt-drag mask preview |
 | LR-EDIT-DETAIL-NR | Luminance noise reduction | P0 | ✅ | `ctl:detail.nrLuminance`, `ctl:detail.nrDetail`, `ctl:detail.nrContrast` | |
 | LR-EDIT-DETAIL-CNR | Colour noise reduction | P0 | ✅ | `ctl:detail.nrColor`, `ctl:detail.nrColorDetail`, `ctl:detail.nrColorSmoothness` | |
-| LR-EDIT-DETAIL-DENOISE | AI denoise | P2 | 🟡 | cmd:denoise.toggle, cmd:denoise.models.install, cmd:denoise.queue, ctl:enhance.denoise, `crates/denoise/`, `docs/denoise.md` | non-destructive Bayer RAW, opt-in weights, pure-Rust CPU/GPU; GPU convolution uses independently written shared scalars (Metal equivalence regression, issue #479); X-Trans/linear RGB, model policy and Lightroom fidelity remain |
+| LR-EDIT-DETAIL-DENOISE | AI denoise | P2 | 🟡 | cmd:denoise.toggle, cmd:denoise.models.install, cmd:denoise.queue, ctl:enhance.denoise, `crates/denoise/`, `docs/denoise.md` | non-destructive Bayer RAW, opt-in weights, pure-Rust CPU/GPU; GPU convolution uses independently written shared scalars (Metal equivalence regression, issue #479); tiles can also run on another computer's graphics card (`lightcraft-cli denoise-serve`, `crates/denoise/src/remote.rs`); X-Trans/linear RGB, model policy and Lightroom fidelity remain |
 | LR-EDIT-DETAIL-RAWDETAILS | Improved demosaic toggle | P2 | ⬜ | | |
 | LR-EDIT-DETAIL-SUPERRES | Super resolution | P2 | ⬜ | | |
 | LR-EDIT-DETAIL-AISHARPEN | AI sharpen | OOS | 🚫 | | |