fix(#7): validate parameter ranges at startup

src/main.rs

@@ -112,9 +112,51 @@ struct Args {
     tint: i32,
 }
 
+/// Validate that all adjustment parameters are within their documented ranges.
+fn validate_params(args: &Args) -> Result<(), Box<dyn std::error::Error>> {
+    if args.exposure < -2.0 || args.exposure > 2.0 {
+        return Err("--exposure must be between -2.0 and 2.0".into());
+    }
+    let range = -100i32..=100i32;
+    if !range.contains(&args.contrast) {
+        return Err("--contrast must be between -100 and 100".into());
+    }
+    if !range.contains(&args.highlights) {
+        return Err("--highlights must be between -100 and 100".into());
+    }
+    if !range.contains(&args.shadows) {
+        return Err("--shadows must be between -100 and 100".into());
+    }
+    if !range.contains(&args.whites) {
+        return Err("--whites must be between -100 and 100".into());
+    }
+    if !range.contains(&args.blacks) {
+        return Err("--blacks must be between -100 and 100".into());
+    }
+    if !range.contains(&args.clarity) {
+        return Err("--clarity must be between -100 and 100".into());
+    }
+    if !range.contains(&args.vibrance) {
+        return Err("--vibrance must be between -100 and 100".into());
+    }
+    if !range.contains(&args.saturation) {
+        return Err("--saturation must be between -100 and 100".into());
+    }
+    if !range.contains(&args.temperature) {
+        return Err("--temperature must be between -100 and 100".into());
+    }
+    if !range.contains(&args.tint) {
+        return Err("--tint must be between -100 and 100".into());
+    }
+    Ok(())
+}
+
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     let args = Args::parse();
 
+    // Validate parameter ranges before processing
+    validate_params(&args)?;
+
     println!("Photo Editor v0.1");
     println!("==================");
     println!("Input file:  {}", args.input);