diff --git a/src/core/index_filter.rs b/src/core/index_filter.rs
new file mode 100644
index 0000000..ab0c139
--- /dev/null
+++ b/src/core/index_filter.rs
@@ -0,0 +1,118 @@
+use std::fs;
+use std::path::Path;
+
+pub(crate) fn should_index_path(path: &Path, max_file_size: u64) -> bool {
+    if let Ok(metadata) = fs::metadata(path) {
+        if metadata.len() > max_file_size {
+            return false;
+        }
+    }
+
+    let ext = path
+        .extension()
+        .and_then(|e| e.to_str())
+        .unwrap_or("")
+        .to_lowercase();
+
+    matches!(
+        ext.as_str(),
+        "rs" | "py"
+            | "js"
+            | "ts"
+            | "tsx"
+            | "jsx"
+            | "go"
+            | "c"
+            | "cpp"
+            | "h"
+            | "hpp"
+            | "java"
+            | "kt"
+            | "swift"
+            | "rb"
+            | "php"
+            | "cs"
+            | "fs"
+            | "scala"
+            | "clj"
+            | "ex"
+            | "exs"
+            | "erl"
+            | "hs"
+            | "ml"
+            | "lua"
+            | "r"
+            | "jl"
+            | "dart"
+            | "vue"
+            | "svelte"
+            | "astro"
+            | "html"
+            | "htm"
+            | "css"
+            | "scss"
+            | "sass"
+            | "less"
+            | "json"
+            | "yaml"
+            | "yml"
+            | "toml"
+            | "xml"
+            | "md"
+            | "markdown"
+            | "txt"
+            | "rst"
+            | "tex"
+            | "sh"
+            | "bash"
+            | "zsh"
+            | "fish"
+            | "ps1"
+            | "bat"
+            | "cmd"
+            | "sql"
+            | "graphql"
+            | "proto"
+    ) || path.file_name().is_some_and(|n| {
+        let name = n.to_string_lossy().to_lowercase();
+        matches!(
+            name.as_str(),
+            "dockerfile"
+                | "makefile"
+                | "cmakelists.txt"
+                | "rakefile"
+                | "gemfile"
+                | "podfile"
+                | "vagrantfile"
+                | ".gitignore"
+                | ".dockerignore"
+                | ".env.example"
+                | "readme"
+                | "license"
+                | "changelog"
+        )
+    })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn does_not_index_extensionless_files_by_default() {
+        assert!(!should_index_path(Path::new("my_binary"), 512 * 1024));
+    }
+
+    #[test]
+    fn indexes_known_extensionless_filenames() {
+        assert!(should_index_path(Path::new("Makefile"), 512 * 1024));
+        assert!(should_index_path(Path::new("Dockerfile"), 512 * 1024));
+        assert!(should_index_path(Path::new("README"), 512 * 1024));
+    }
+
+    #[test]
+    fn indexes_known_extensions() {
+        assert!(should_index_path(Path::new("src/main.rs"), 512 * 1024));
+        assert!(should_index_path(Path::new("script.SH"), 512 * 1024));
+    }
+}
diff --git a/src/core/indexer.rs b/src/core/indexer.rs
index 469c120..34bb880 100644
--- a/src/core/indexer.rs
+++ b/src/core/indexer.rs
@@ -236,97 +236,7 @@ impl Indexer {
     }
 
     fn should_index(&self, path: &Path) -> bool {
-        if let Ok(metadata) = fs::metadata(path) {
-            if metadata.len() > self.max_file_size {
-                return false;
-            }
-        }
-
-        let ext = path
-            .extension()
-            .and_then(|e| e.to_str())
-            .unwrap_or("")
-            .to_lowercase();
-
-        matches!(
-            ext.as_str(),
-            "rs" | "py"
-                | "js"
-                | "ts"
-                | "tsx"
-                | "jsx"
-                | "go"
-                | "c"
-                | "cpp"
-                | "h"
-                | "hpp"
-                | "java"
-                | "kt"
-                | "swift"
-                | "rb"
-                | "php"
-                | "cs"
-                | "fs"
-                | "scala"
-                | "clj"
-                | "ex"
-                | "exs"
-                | "erl"
-                | "hs"
-                | "ml"
-                | "lua"
-                | "r"
-                | "jl"
-                | "dart"
-                | "vue"
-                | "svelte"
-                | "astro"
-                | "html"
-                | "htm"
-                | "css"
-                | "scss"
-                | "sass"
-                | "less"
-                | "json"
-                | "yaml"
-                | "yml"
-                | "toml"
-                | "xml"
-                | "md"
-                | "markdown"
-                | "txt"
-                | "rst"
-                | "tex"
-                | "sh"
-                | "bash"
-                | "zsh"
-                | "fish"
-                | "ps1"
-                | "bat"
-                | "cmd"
-                | "sql"
-                | "graphql"
-                | "proto"
-                | ""
-        ) || path.file_name().is_some_and(|n| {
-            let name = n.to_string_lossy().to_lowercase();
-            matches!(
-                name.as_str(),
-                "dockerfile"
-                    | "makefile"
-                    | "cmakelists.txt"
-                    | "rakefile"
-                    | "gemfile"
-                    | "podfile"
-                    | "vagrantfile"
-                    | ".gitignore"
-                    | ".dockerignore"
-                    | ".env.example"
-                    | "readme"
-                    | "license"
-                    | "changelog"
-            )
-        })
+        super::index_filter::should_index_path(path, self.max_file_size)
     }
 
     fn chunk_content(&self, content: &str) -> Vec<FileChunk> {
@@ -612,97 +522,7 @@ impl ServerIndexer {
     }
 
     fn should_index(&self, path: &Path) -> bool {
-        if let Ok(metadata) = fs::metadata(path) {
-            if metadata.len() > self.max_file_size {
-                return false;
-            }
-        }
-
-        let ext = path
-            .extension()
-            .and_then(|e| e.to_str())
-            .unwrap_or("")
-            .to_lowercase();
-
-        matches!(
-            ext.as_str(),
-            "rs" | "py"
-                | "js"
-                | "ts"
-                | "tsx"
-                | "jsx"
-                | "go"
-                | "c"
-                | "cpp"
-                | "h"
-                | "hpp"
-                | "java"
-                | "kt"
-                | "swift"
-                | "rb"
-                | "php"
-                | "cs"
-                | "fs"
-                | "scala"
-                | "clj"
-                | "ex"
-                | "exs"
-                | "erl"
-                | "hs"
-                | "ml"
-                | "lua"
-                | "r"
-                | "jl"
-                | "dart"
-                | "vue"
-                | "svelte"
-                | "astro"
-                | "html"
-                | "htm"
-                | "css"
-                | "scss"
-                | "sass"
-                | "less"
-                | "json"
-                | "yaml"
-                | "yml"
-                | "toml"
-                | "xml"
-                | "md"
-                | "markdown"
-                | "txt"
-                | "rst"
-                | "tex"
-                | "sh"
-                | "bash"
-                | "zsh"
-                | "fish"
-                | "ps1"
-                | "bat"
-                | "cmd"
-                | "sql"
-                | "graphql"
-                | "proto"
-                | ""
-        ) || path.file_name().is_some_and(|n| {
-            let name = n.to_string_lossy().to_lowercase();
-            matches!(
-                name.as_str(),
-                "dockerfile"
-                    | "makefile"
-                    | "cmakelists.txt"
-                    | "rakefile"
-                    | "gemfile"
-                    | "podfile"
-                    | "vagrantfile"
-                    | ".gitignore"
-                    | ".dockerignore"
-                    | ".env.example"
-                    | "readme"
-                    | "license"
-                    | "changelog"
-            )
-        })
+        super::index_filter::should_index_path(path, self.max_file_size)
     }
 
     fn chunk_content(&self, content: &str) -> Vec<FileChunk> {
diff --git a/src/core/mod.rs b/src/core/mod.rs
index ba223a5..b04fdfa 100644
--- a/src/core/mod.rs
+++ b/src/core/mod.rs
@@ -2,6 +2,7 @@
 
 mod db;
 mod embeddings;
+pub(crate) mod index_filter;
 mod indexer;
 mod search;
 
diff --git a/src/watcher.rs b/src/watcher.rs
index 816219f..9f42b5f 100644
--- a/src/watcher.rs
+++ b/src/watcher.rs
@@ -168,99 +168,7 @@ impl FileWatcher {
             }
         }
 
-        // Check file size
-        if let Ok(metadata) = std::fs::metadata(path) {
-            if metadata.len() > self.config.max_file_size {
-                return false;
-            }
-        }
-
-        // Check extension
-        let ext = path
-            .extension()
-            .and_then(|e| e.to_str())
-            .unwrap_or("")
-            .to_lowercase();
-
-        matches!(
-            ext.as_str(),
-            "rs" | "py"
-                | "js"
-                | "ts"
-                | "tsx"
-                | "jsx"
-                | "go"
-                | "c"
-                | "cpp"
-                | "h"
-                | "hpp"
-                | "java"
-                | "kt"
-                | "swift"
-                | "rb"
-                | "php"
-                | "cs"
-                | "fs"
-                | "scala"
-                | "clj"
-                | "ex"
-                | "exs"
-                | "erl"
-                | "hs"
-                | "ml"
-                | "lua"
-                | "r"
-                | "jl"
-                | "dart"
-                | "vue"
-                | "svelte"
-                | "astro"
-                | "html"
-                | "htm"
-                | "css"
-                | "scss"
-                | "sass"
-                | "less"
-                | "json"
-                | "yaml"
-                | "yml"
-                | "toml"
-                | "xml"
-                | "md"
-                | "markdown"
-                | "txt"
-                | "rst"
-                | "tex"
-                | "sh"
-                | "bash"
-                | "zsh"
-                | "fish"
-                | "ps1"
-                | "bat"
-                | "cmd"
-                | "sql"
-                | "graphql"
-                | "proto"
-                | ""
-        ) || path.file_name().is_some_and(|n| {
-            let name = n.to_string_lossy().to_lowercase();
-            matches!(
-                name.as_str(),
-                "dockerfile"
-                    | "makefile"
-                    | "cmakelists.txt"
-                    | "rakefile"
-                    | "gemfile"
-                    | "podfile"
-                    | "vagrantfile"
-                    | ".gitignore"
-                    | ".dockerignore"
-                    | ".env.example"
-                    | "readme"
-                    | "license"
-                    | "changelog"
-            )
-        })
+        crate::core::index_filter::should_index_path(path, self.config.max_file_size)
     }
 
     fn index_all(&self) -> Result<()> {
@@ -453,3 +361,20 @@ struct FileChunk {
     start_line: i32,
     end_line: i32,
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn should_not_index_extensionless_files() {
+        let watcher = FileWatcher::new(Config::default(), PathBuf::from("."));
+        assert!(!watcher.should_index(Path::new("my_binary")));
+    }
+
+    #[test]
+    fn should_index_known_extensionless_filenames() {
+        let watcher = FileWatcher::new(Config::default(), PathBuf::from("."));
+        assert!(watcher.should_index(Path::new("Makefile")));
+    }
+}