Use shared image codecs for CLI previews

Cargo.lock

@@ -1719,6 +1719,7 @@ name = "designcraft-cli"
 version = "0.20.1"
 dependencies = [
  "craft-file-formats",
+ "craft-image-codecs",
  "designcraft-color",
  "designcraft-compose",
  "designcraft-doc",

apps/designcraft-cli/Cargo.toml

@@ -23,5 +23,6 @@ designcraft-format = { workspace = true }
 designcraft-pdf = { workspace = true }
 designcraft-mcp = { workspace = true }
 craft-file-formats = { workspace = true }
+craft-image-codecs = { workspace = true }
 image = { workspace = true }
 serde_json = { workspace = true }

apps/designcraft-cli/src/main.rs

@@ -319,16 +319,17 @@ fn names_the_same_file(input: &std::path::Path, out: &std::path::Path) -> bool {
 /// as it is; it is decoded anyway, so a broken one is an error rather than an unreadable thumbnail.
 fn fit_png(png: Vec<u8>, size: Option<u32>) -> Result<Vec<u8>, String> {
     // The preview comes from the file: it may claim any size.
-    let mut limits = image::Limits::default();
-    limits.max_image_width = Some(4096);
-    limits.max_image_height = Some(4096);
-    let mut reader = image::ImageReader::with_format(std::io::Cursor::new(&png), image::ImageFormat::Png);
-    reader.limits(limits);
-    let img = reader.decode().map_err(|e| e.to_string())?;
-    let Some(size) = size.filter(|s| img.width().max(img.height()) > *s) else { return Ok(png) };
-    let mut out = std::io::Cursor::new(Vec::new());
-    img.resize(size, size, image::imageops::FilterType::Triangle).write_to(&mut out, image::ImageFormat::Png).map_err(|e| e.to_string())?;
-    Ok(out.into_inner())
+    let info = craft_image_codecs::inspect_raster(&png).map_err(|e| e.to_string())?.ok_or("invalid PNG preview")?;
+    if info.width > 4096 || info.height > 4096 {
+        return Err("preview is larger than 4096 pixels".into());
+    }
+    let decoded = craft_image_codecs::decode(&png).map_err(|e| e.to_string())?;
+    let Some(size) = size.filter(|s| decoded.width().max(decoded.height()) > *s) else { return Ok(png) };
+    let rgba = image::RgbaImage::from_raw(decoded.width(), decoded.height(), decoded.to_rgba8()).ok_or("invalid PNG pixel data")?;
+    let resized = image::DynamicImage::ImageRgba8(rgba).resize(size, size, image::imageops::FilterType::Triangle).to_rgba8();
+    let encoded = craft_image_codecs::Image::from_u8(resized.width(), resized.height(), craft_image_codecs::ChannelLayout::Rgba, resized.into_raw())
+        .map_err(|e| e.to_string())?;
+    craft_image_codecs::encode(&encoded, craft_image_codecs::Format::Png, &Default::default()).map_err(|e| e.to_string())
 }
 
 /// `mcp` (headless, in-process engine) or `mcp --connect PORT|HOST:PORT` (drive a running app