diff --git a/src/icon_index.rs b/src/icon_index.rs
new file mode 100644
index 0000000..901efab
--- /dev/null
+++ b/src/icon_index.rs
@@ -0,0 +1,89 @@
+use std::path::{Path, PathBuf};
+use walkdir::WalkDir;
+
+pub fn list_svg_icons(root: &Path) -> Vec<PathBuf> {
+    WalkDir::new(root)
+        .into_iter()
+        .filter_map(|e| e.ok())
+        .filter(|e| e.file_type().is_file())
+        .filter(|e| e.path().extension().and_then(|s| s.to_str()) == Some("svg"))
+        .map(|e| e.path().to_path_buf())
+        .collect()
+}
+
+pub fn fuzzy_match(query: &str, candidate: &str) -> bool {
+    if query.is_empty() {
+        return true;
+    }
+    let candidate_lower = candidate.to_lowercase();
+    let mut chars = candidate_lower.chars();
+    for q in query.to_lowercase().chars() {
+        if !chars.any(|c| c == q) {
+            return false;
+        }
+    }
+    true
+}
+
+pub fn filter_icons<'a>(icons: &'a [PathBuf], query: &str, limit: usize) -> Vec<&'a PathBuf> {
+    icons
+        .iter()
+        .filter(|p| fuzzy_match(query, &p.to_string_lossy()))
+        .take(limit)
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn fuzzy_match_empty_query_matches_everything() {
+        assert!(fuzzy_match("", "anything"));
+    }
+
+    #[test]
+    fn fuzzy_match_is_case_insensitive_subsequence() {
+        assert!(fuzzy_match("cls", "actions/16/edit-clear-symbolic.svg"));
+        assert!(fuzzy_match("CLS", "actions/16/edit-clear-symbolic.svg"));
+    }
+
+    #[test]
+    fn fuzzy_match_rejects_out_of_order_or_missing_chars() {
+        assert!(!fuzzy_match("zzz", "actions/16/edit-clear-symbolic.svg"));
+        assert!(!fuzzy_match("scl", "edit-clear-symbolic.svg")); // 's' comes after "cl" here, wrong order
+    }
+
+    #[test]
+    fn filter_icons_applies_query_and_limit() {
+        let icons = vec![
+            PathBuf::from("a/edit-clear.svg"),
+            PathBuf::from("b/edit-copy.svg"),
+            PathBuf::from("c/folder.svg"),
+        ];
+
+        let matches = filter_icons(&icons, "edit", 10);
+        assert_eq!(matches.len(), 2);
+
+        let limited = filter_icons(&icons, "", 1);
+        assert_eq!(limited.len(), 1);
+    }
+
+    #[test]
+    fn list_svg_icons_finds_only_svg_files_recursively() {
+        let dir = std::env::temp_dir().join(format!(
+            "icon-color-tool-test-iconindex-{}",
+            std::process::id()
+        ));
+        let sub = dir.join("actions/16");
+        std::fs::create_dir_all(&sub).unwrap();
+        std::fs::write(sub.join("edit-clear.svg"), "<svg></svg>").unwrap();
+        std::fs::write(sub.join("readme.txt"), "not an icon").unwrap();
+
+        let found = list_svg_icons(&dir);
+        assert_eq!(found.len(), 1);
+        assert!(found[0].ends_with("edit-clear.svg"));
+
+        std::fs::remove_dir_all(&dir).ok();
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index 87f4dd1..8658643 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,6 @@
 mod color_scheme;
 mod config;
+mod icon_index;
 
 use gtk::prelude::*;
 use gtk::{glib, Application, ApplicationWindow};