diff --git a/client/src/components/media/MediaLightbox.jsx b/client/src/components/media/MediaLightbox.jsx
index a365f509d..1570ebf7a 100644
--- a/client/src/components/media/MediaLightbox.jsx
+++ b/client/src/components/media/MediaLightbox.jsx
@@ -378,26 +378,10 @@ function SettingsPane({
   // optional prompt) so a watermark-defeat pass can be tuned without leaving the
   // lightbox. Slider bounds come from the server (`regenBounds`) so the floor
   // stays in lock-step with route validation.
-  const regenMin = typeof regenBounds?.strengthMin === 'number' ? regenBounds.strengthMin : 0.02;
-  const regenMax = typeof regenBounds?.strengthMax === 'number' ? regenBounds.strengthMax : 0.6;
-  const regenDefault = typeof regenBounds?.strengthDefault === 'number' ? regenBounds.strengthDefault : 0.25;
+  const { strengthMin: regenMin = 0.02, strengthMax: regenMax = 0.6, strengthDefault: regenDefault = 0.25 } = regenBounds || {};
   const [regenOpen, setRegenOpen] = useState(false);
   const [regenStrength, setRegenStrength] = useState(regenDefault);
   const [regenPrompt, setRegenPrompt] = useState('');
-  const runRegen = async () => {
-    if (regenerating) return;
-    setRegenerating(true);
-    let ok = false;
-    try {
-      await onRegenerate(item, { strength: regenStrength, prompt: regenPrompt.trim() || undefined });
-      ok = true;
-    } catch {
-      // Caller toasts its own error; stay open so the user can retry.
-    } finally {
-      setRegenerating(false);
-    }
-    if (ok) onClose();
-  };
   const starred = !!annotation?.starred;
   const closeThenRun = (handler) => {
     onClose?.();
@@ -697,7 +681,7 @@ function SettingsPane({
             <button
               type="button"
               disabled={regenerating}
-              onClick={runRegen}
+              onClick={runBusyAction(regenerating, setRegenerating, (it) => onRegenerate(it, { strength: regenStrength, prompt: regenPrompt.trim() || undefined }))}
               className="w-full flex items-center justify-center gap-1.5 px-2 py-1.5 text-xs bg-port-accent text-white hover:opacity-90 rounded disabled:opacity-50 disabled:cursor-not-allowed"
             >
               <Wand2 className="w-3.5 h-3.5" /> {regenerating ? 'Queuing…' : `Regenerate at ${regenStrength.toFixed(2)}`}
diff --git a/server/services/imageGen/local.js b/server/services/imageGen/local.js
index 856a8474d..480d33b5d 100644
--- a/server/services/imageGen/local.js
+++ b/server/services/imageGen/local.js
@@ -707,13 +707,14 @@ export async function generateImage({ pythonPath, prompt, negativePrompt = '', m
       // the watermark-free copy matches the original's resolution. `meta.width/
       // height` currently hold the render dims; record those as render* and
       // promote the delivered dims so the gallery shows the real file size.
-      if (upscaleTo && Number(upscaleTo.width) > 0 && Number(upscaleTo.height) > 0
-          && (Math.round(upscaleTo.width) !== meta.width || Math.round(upscaleTo.height) !== meta.height)) {
-        const targetW = Math.round(upscaleTo.width);
-        const targetH = Math.round(upscaleTo.height);
+      const targetW = Math.round(Number(upscaleTo?.width));
+      const targetH = Math.round(Number(upscaleTo?.height));
+      if (targetW > 0 && targetH > 0 && (targetW !== meta.width || targetH !== meta.height)) {
         const resized = await sharp(outputPath)
           .resize(targetW, targetH, { fit: 'fill', kernel: 'lanczos3' })
-          .png({ compressionLevel: 9 })
+          // compressionLevel 6 (sharp default) — near-identical size to 9 but
+          // markedly faster, and this re-encode is on the render-completion path.
+          .png({ compressionLevel: 6 })
           .toBuffer()
           .catch((err) => { console.warn(`⚠️ Regen upscale failed for ${filename}: ${err?.message || err}`); return null; });
         if (resized) {
diff --git a/server/services/imageGen/regen.js b/server/services/imageGen/regen.js
index cadda1612..621195ff4 100644
--- a/server/services/imageGen/regen.js
+++ b/server/services/imageGen/regen.js
@@ -212,7 +212,7 @@ export async function readImageDimensions(absPath) {
 export function buildRegenParams({ filename, sourceAbsPath, sourceMeta = {}, sourceDims = null, model, pythonPath, strength, steps, promptOverride }) {
   const src = sourceDims
     || (sourceMeta.width && sourceMeta.height ? { width: Math.round(sourceMeta.width), height: Math.round(sourceMeta.height) } : null);
-  const hasPrompt = typeof promptOverride === 'string' && promptOverride.trim();
+  const trimmedPrompt = typeof promptOverride === 'string' ? promptOverride.trim() : '';
   // Anchor the variant-grouping lineage at the ROOT original, not the clicked
   // image. computeImageVariantGroup groups siblings under a single original
   // (an item with no `cleanedFrom`); regenerating a cleaned/regenerated variant
@@ -226,8 +226,8 @@ export function buildRegenParams({ filename, sourceAbsPath, sourceMeta = {}, sou
     mode: IMAGE_GEN_MODE.LOCAL,
     pythonPath,
     modelId: model.id,
-    prompt: hasPrompt ? promptOverride : '',
-    negativePrompt: hasPrompt && typeof sourceMeta.negativePrompt === 'string' ? sourceMeta.negativePrompt : '',
+    prompt: trimmedPrompt,
+    negativePrompt: trimmedPrompt && typeof sourceMeta.negativePrompt === 'string' ? sourceMeta.negativePrompt : '',
     initImagePath: sourceAbsPath,
     initImageStrength: strength,
     regenOf: groupRoot,