wallpaper: upscale a too-small staged image in place

A staged wallpaper smaller than its screen (yellow or red border) gets an
"Upscale 4x" button. It rewrites the file with Real-ESRGAN through
stable-diffusion.cpp's `sd-cli -M upscale`, keeping the name, so wallp's
state and the engine's lists, which name it by path, still find it.
sd-cli writes to a dot-named sibling the scan skips, and only a
successful run is moved over the original.

Success needs no [E] line as well as exit 0: with a model that fails to
load, sd-cli logs "[E] new_upscaler_ctx failed", saves the input
unscaled and exits 0 (measured).

The button takes two clicks so the model choice shows before anything is
rewritten. The first runs Imajev-4B, a small Jev-style vision decision
model, through llama-mtmd-cli on a 512 px thumbnail, with a grammar that
allows only A (anime) or B (photo or render); greedy decoding then
returns the higher-logit option, about 1.7 s. The label becomes
"Upscale 4x (anime)" or "(photo)", and the second click upscales with
the anime or the general model. Anything but A, including a failed
decider, picks the general model, safe on any image.

Imajev-4B was chosen by measurement on 22 wallpapers: all 12 anime and 4
photos right, 4 of 6 painted 3D renders called anime (those come out
smoother than painted). The 2B got 17 of 22, leaning to photo; a
three-way prompt adding "painted or render" dropped both to 15 or
fewer, with most anime called painted.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 87 insertions, 0 deletions

diff --git a/desktop/modules/appearance/Wallpapers.qml b/desktop/modules/appearance/Wallpapers.qml
index 4d06a2e..73c1f25 100644
--- a/desktop/modules/appearance/Wallpapers.qml
+++ b/desktop/modules/appearance/Wallpapers.qml
@@ -150,6 +150,93 @@ Singleton {
                           : "each image pixel becomes a visible block, so it will look pixelated.");
     }
 
+    // Real-ESRGAN through stable-diffusion.cpp's sd-cli, for an image too
+    // small for its screen. The file is replaced in place, so wallp's state
+    // and the engine's lists, which name it by path, still find it. sd-cli
+    // writes to a dot-named sibling first, which the scan skips, and only a
+    // successful run is moved over the original, so a failure leaves it
+    // untouched. The name keeps its extension because sd-cli writes the
+    // format the extension names. Only files under `dir`: the system ones
+    // are not ours to rewrite. Success is no [E] line as well as exit 0: a
+    // model that fails to load logs "[E] new_upscaler_ctx failed", saves
+    // the input unscaled and exits 0 (measured).
+    //
+    // Which Real-ESRGAN model is decided first, as its own step, so the page
+    // can show the choice before anything is rewritten. Imajev-4B makes it,
+    // a small Jev-style vision decision model, run once through llama-mtmd-cli on a
+    // 512 px thumbnail: the answer is held to one token, A or B, by a
+    // grammar, so greedy decoding returns the option with the highest logit,
+    // which is the decision. About 1.7 s. Anime goes to the anime model,
+    // which keeps line art clean; everything else, and any failure of the
+    // decider, goes to the general one, safe on any image. Measured on 22
+    // wallpapers it got every anime and photo right and called 4 of 6
+    // painted 3D renders anime, which then come out smoother than painted;
+    // the 2B, and a three-way prompt adding "painted or render", did worse.
+    // ponytail: argmax only, so Imajev's calibration temperature is not
+    // needed. One 4x pass, which covers both screens unless the image is
+    // under 640 px wide or 480 px tall; --upscale-repeats if that matters.
+    readonly property string upscalers: "/data/LLM-models/SD/upscalers"
+    readonly property string decider: "/data/LLM-models/SD/imajev/imajev-4b"
+    property string upscaling: ""
+    property string upscaleError: ""
+    function canUpscale(path, which) {
+        return path.startsWith(dir + "/") && upscale(path, which) > 1;
+    }
+    function sibling(path) { return path.slice(0, path.lastIndexOf("/") + 1) + "." + basename(path); }
+
+    // The decision for one image: decidedFor is the path it was made for, so
+    // staging another image leaves it standing for the first and unread.
+    property string deciding: ""
+    property string decidedFor: ""
+    property string decidedKind: ""   // "anime" or "photo"
+    function decide(path) {
+        if (deciding !== "" || upscaling !== "" || path === "") return;
+        deciding = path;
+        upscaleError = "";
+        decideProc.command = ["sh", "-c",
+            'magick "$1" -resize 512x512 "$2" 2>/dev/null; '
+            + 'llama-mtmd-cli -m "$3-Q4_K_M.gguf" --mmproj "$3-mmproj-f16.gguf" --image "$2" '
+            + '-ngl 99 --temp 0 -n 1 --grammar "$5" -p "$4" 2>/dev/null; rm -f "$2"',
+            "sh", path, sibling(path) + ".jpg", decider,
+            "Is this image A) anime, cartoon or illustration art, or B) a photograph or realistic render? Answer A or B.",
+            'root ::= "A" | "B"'];
+        decideProc.running = true;
+    }
+    Process {
+        id: decideProc
+        stdout: StdioCollector { id: decideOut }
+        onExited: {
+            root.decidedKind = decideOut.text.trim().endsWith("A") ? "anime" : "photo";
+            root.decidedFor = root.deciding;
+            root.deciding = "";
+        }
+    }
+
+    function upscaleFile(path) {
+        if (upscaling !== "" || path === "" || path !== decidedFor) return;
+        upscaling = path;
+        upscaleError = "";
+        upscaleProc.command = ["sh", "-c",
+            'log=$(sd-cli -M upscale --upscale-model "$1" -i "$2" -o "$3" 2>&1); s=$?; '
+            + 'err=$(printf "%s\\n" "$log" | grep -F "[E]"); '
+            + 'if [ $s -eq 0 ] && [ -z "$err" ]; then mv -f "$3" "$2"; '
+            + 'else rm -f "$3"; echo "${err:-sd-cli exited $s}" >&2; exit 1; fi',
+            "sh", `${upscalers}/RealESRGAN_x4plus${decidedKind === "anime" ? "_anime_6B" : ""}.pth`,
+            path, sibling(path)];
+        upscaleProc.running = true;
+    }
+    Process {
+        id: upscaleProc
+        stderr: StdioCollector { id: upscaleErr }
+        onExited: code => {
+            if (code !== 0) root.upscaleError = `upscaling ${root.basename(root.upscaling)} failed: ${upscaleErr.text.trim()}`;
+            root.decidedFor = "";
+            root.upscaling = "";
+            // The new size clears the quality note and the red border.
+            root.refresh();
+        }
+    }
+
     function basename(path) { return path.slice(path.lastIndexOf("/") + 1); }
 
     // The files by the subfolder they sit in, folders by name, each keeping