diff --git a/shared/src/main/kotlin/io/askimo/core/chat/util/FileTypeSupport.kt b/shared/src/main/kotlin/io/askimo/core/chat/util/FileTypeSupport.kt
index fba9e65c..3788e3db 100644
--- a/shared/src/main/kotlin/io/askimo/core/chat/util/FileTypeSupport.kt
+++ b/shared/src/main/kotlin/io/askimo/core/chat/util/FileTypeSupport.kt
@@ -43,18 +43,6 @@ object FileTypeSupport {
         "nix", "dhall",
     )
 
-    /**
-     * Config files without extensions (treated as code files).
-     */
-    val CONFIG_EXTENSIONS = setOf(
-        "dockerfile",
-        "makefile",
-        "gemfile",
-        "rakefile",
-        "procfile",
-        "vagrantfile",
-    )
-
     /**
      * Document file extensions (for content extraction).
      */
@@ -76,6 +64,23 @@ object FileTypeSupport {
         "bmp",
     )
 
+    /**
+     * Extensionless configuration filenames stored in lowercase.
+     * These files have no extension but are recognised by their full filename.
+     */
+    val CONFIG_EXTENSIONS = setOf(
+        "dockerfile",
+        "makefile",
+        "jenkinsfile",
+        "procfile",
+        "vagrantfile",
+        "rakefile",
+        "gemfile",
+        "podfile",
+        "brewfile",
+        "guardfile",
+    )
+
     /**
      * All text-extractable file extensions.
      * These files have their content extracted and included in the prompt.
@@ -119,4 +124,13 @@ object FileTypeSupport {
      * @return The extension without the dot, or empty string if no extension
      */
     fun getExtension(fileName: String): String = fileName.substringAfterLast('.', "")
+
+    /**
+     * Check if a filename is a known extensionless configuration file.
+     * Comparison is case-insensitive.
+     *
+     * @param fileName The file name (without path)
+     * @return true if the filename is in CONFIG_EXTENSIONS
+     */
+    fun isConfigFile(fileName: String): Boolean = fileName.lowercase() in CONFIG_EXTENSIONS
 }
diff --git a/shared/src/test/kotlin/io/askimo/core/chat/util/FileTypeSupportTest.kt b/shared/src/test/kotlin/io/askimo/core/chat/util/FileTypeSupportTest.kt
index 50923bee..078f558b 100644
--- a/shared/src/test/kotlin/io/askimo/core/chat/util/FileTypeSupportTest.kt
+++ b/shared/src/test/kotlin/io/askimo/core/chat/util/FileTypeSupportTest.kt
@@ -5,10 +5,181 @@
 package io.askimo.core.chat.util
 
 import org.junit.jupiter.api.Test
+import kotlin.test.assertEquals
 import kotlin.test.assertFalse
 import kotlin.test.assertTrue
 
 class FileTypeSupportTest {
+
+    // ============================================================================
+    // isImageExtension
+    // ============================================================================
+
+    @Test
+    fun `isImageExtension returns true for jpg`() {
+        assertTrue(FileTypeSupport.isImageExtension("jpg"))
+    }
+
+    @Test
+    fun `isImageExtension returns true for jpeg`() {
+        assertTrue(FileTypeSupport.isImageExtension("jpeg"))
+    }
+
+    @Test
+    fun `isImageExtension returns true for png`() {
+        assertTrue(FileTypeSupport.isImageExtension("png"))
+    }
+
+    @Test
+    fun `isImageExtension returns true for gif`() {
+        assertTrue(FileTypeSupport.isImageExtension("gif"))
+    }
+
+    @Test
+    fun `isImageExtension returns true for webp`() {
+        assertTrue(FileTypeSupport.isImageExtension("webp"))
+    }
+
+    @Test
+    fun `isImageExtension returns true for bmp`() {
+        assertTrue(FileTypeSupport.isImageExtension("bmp"))
+    }
+
+    @Test
+    fun `isImageExtension accepts extension with leading dot`() {
+        assertTrue(FileTypeSupport.isImageExtension(".png"))
+    }
+
+    @Test
+    fun `isImageExtension is case insensitive`() {
+        assertTrue(FileTypeSupport.isImageExtension("JPG"))
+        assertTrue(FileTypeSupport.isImageExtension("PNG"))
+        assertTrue(FileTypeSupport.isImageExtension(".WEBP"))
+    }
+
+    @Test
+    fun `isImageExtension returns false for text extension`() {
+        assertFalse(FileTypeSupport.isImageExtension("txt"))
+    }
+
+    @Test
+    fun `isImageExtension returns false for code extension`() {
+        assertFalse(FileTypeSupport.isImageExtension("kt"))
+    }
+
+    @Test
+    fun `isImageExtension returns false for document extension`() {
+        assertFalse(FileTypeSupport.isImageExtension("pdf"))
+    }
+
+    @Test
+    fun `isImageExtension returns false for video extension`() {
+        assertFalse(FileTypeSupport.isImageExtension("mp4"))
+    }
+
+    @Test
+    fun `isImageExtension returns false for empty string`() {
+        assertFalse(FileTypeSupport.isImageExtension(""))
+    }
+
+    // ============================================================================
+    // isTextExtractable – TEXT_EXTENSIONS
+    // ============================================================================
+
+    @Test
+    fun `isTextExtractable returns true for txt`() {
+        assertTrue(FileTypeSupport.isTextExtractable("txt"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for md`() {
+        assertTrue(FileTypeSupport.isTextExtractable("md"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for json`() {
+        assertTrue(FileTypeSupport.isTextExtractable("json"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for yaml`() {
+        assertTrue(FileTypeSupport.isTextExtractable("yaml"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for yml`() {
+        assertTrue(FileTypeSupport.isTextExtractable("yml"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for csv`() {
+        assertTrue(FileTypeSupport.isTextExtractable("csv"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for sh`() {
+        assertTrue(FileTypeSupport.isTextExtractable("sh"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for env`() {
+        assertTrue(FileTypeSupport.isTextExtractable("env"))
+    }
+
+    // ============================================================================
+    // isTextExtractable – CODE_EXTENSIONS
+    // ============================================================================
+
+    @Test
+    fun `isTextExtractable returns true for kt`() {
+        assertTrue(FileTypeSupport.isTextExtractable("kt"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for java`() {
+        assertTrue(FileTypeSupport.isTextExtractable("java"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for py`() {
+        assertTrue(FileTypeSupport.isTextExtractable("py"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for js`() {
+        assertTrue(FileTypeSupport.isTextExtractable("js"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for ts`() {
+        assertTrue(FileTypeSupport.isTextExtractable("ts"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for go`() {
+        assertTrue(FileTypeSupport.isTextExtractable("go"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for rs`() {
+        assertTrue(FileTypeSupport.isTextExtractable("rs"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for sql`() {
+        assertTrue(FileTypeSupport.isTextExtractable("sql"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for html`() {
+        assertTrue(FileTypeSupport.isTextExtractable("html"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for css`() {
+        assertTrue(FileTypeSupport.isTextExtractable("css"))
+    }
+
     @Test
     fun `test new config file extensions`() {
         assertTrue(FileTypeSupport.isTextExtractable("toml"))
@@ -53,6 +224,260 @@ class FileTypeSupportTest {
         assertTrue(FileTypeSupport.isTextExtractable("dhall"))
     }
 
+    // ============================================================================
+    // isTextExtractable – DOCUMENT_EXTENSIONS
+    // ============================================================================
+
+    @Test
+    fun `isTextExtractable returns true for pdf`() {
+        assertTrue(FileTypeSupport.isTextExtractable("pdf"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for docx`() {
+        assertTrue(FileTypeSupport.isTextExtractable("docx"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for doc`() {
+        assertTrue(FileTypeSupport.isTextExtractable("doc"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for xlsx`() {
+        assertTrue(FileTypeSupport.isTextExtractable("xlsx"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for pptx`() {
+        assertTrue(FileTypeSupport.isTextExtractable("pptx"))
+    }
+
+    @Test
+    fun `isTextExtractable returns true for rtf`() {
+        assertTrue(FileTypeSupport.isTextExtractable("rtf"))
+    }
+
+    @Test
+    fun `isTextExtractable accepts extension with leading dot`() {
+        assertTrue(FileTypeSupport.isTextExtractable(".pdf"))
+        assertTrue(FileTypeSupport.isTextExtractable(".kt"))
+        assertTrue(FileTypeSupport.isTextExtractable(".txt"))
+    }
+
+    @Test
+    fun `isTextExtractable is case insensitive`() {
+        assertTrue(FileTypeSupport.isTextExtractable("PDF"))
+        assertTrue(FileTypeSupport.isTextExtractable("KT"))
+        assertTrue(FileTypeSupport.isTextExtractable("TXT"))
+    }
+
+    @Test
+    fun `isTextExtractable returns false for image extension`() {
+        assertFalse(FileTypeSupport.isTextExtractable("jpg"))
+        assertFalse(FileTypeSupport.isTextExtractable("png"))
+    }
+
+    @Test
+    fun `isTextExtractable returns false for unknown extension`() {
+        assertFalse(FileTypeSupport.isTextExtractable("xyz"))
+        assertFalse(FileTypeSupport.isTextExtractable("mp4"))
+    }
+
+    @Test
+    fun `isTextExtractable returns false for empty string`() {
+        assertFalse(FileTypeSupport.isTextExtractable(""))
+    }
+
+    // ============================================================================
+    // getExtension
+    // ============================================================================
+
+    @Test
+    fun `getExtension returns extension for simple filename`() {
+        assertEquals("txt", FileTypeSupport.getExtension("readme.txt"))
+    }
+
+    @Test
+    fun `getExtension returns extension for kotlin file`() {
+        assertEquals("kt", FileTypeSupport.getExtension("Main.kt"))
+    }
+
+    @Test
+    fun `getExtension returns empty string for extensionless file`() {
+        assertEquals("", FileTypeSupport.getExtension("Dockerfile"))
+        assertEquals("", FileTypeSupport.getExtension("Makefile"))
+    }
+
+    @Test
+    fun `getExtension returns last segment for double extension`() {
+        assertEquals("gz", FileTypeSupport.getExtension("archive.tar.gz"))
+    }
+
+    @Test
+    fun `getExtension returns last segment for triple extension`() {
+        assertEquals("gz", FileTypeSupport.getExtension("data.tar.bz2.gz"))
+    }
+
+    @Test
+    fun `getExtension returns extension part for dotfile`() {
+        assertEquals("gitignore", FileTypeSupport.getExtension(".gitignore"))
+        assertEquals("dockerignore", FileTypeSupport.getExtension(".dockerignore"))
+        assertEquals("editorconfig", FileTypeSupport.getExtension(".editorconfig"))
+    }
+
+    @Test
+    fun `getExtension returns empty string for empty input`() {
+        assertEquals("", FileTypeSupport.getExtension(""))
+    }
+
+    @Test
+    fun `getExtension returns empty string for filename without dot`() {
+        assertEquals("", FileTypeSupport.getExtension("noextension"))
+    }
+
+    @Test
+    fun `getExtension returns extension when filename has path-like dots`() {
+        assertEquals("kt", FileTypeSupport.getExtension("com.example.Main.kt"))
+    }
+
+    // ============================================================================
+    // isSupported – ALL_SUPPORTED_EXTENSIONS
+    // ============================================================================
+
+    @Test
+    fun `isSupported returns true for image extension`() {
+        assertTrue(FileTypeSupport.isSupported("jpg"))
+        assertTrue(FileTypeSupport.isSupported("png"))
+        assertTrue(FileTypeSupport.isSupported("webp"))
+    }
+
+    @Test
+    fun `isSupported returns true for text extension`() {
+        assertTrue(FileTypeSupport.isSupported("txt"))
+        assertTrue(FileTypeSupport.isSupported("md"))
+        assertTrue(FileTypeSupport.isSupported("json"))
+    }
+
+    @Test
+    fun `isSupported returns true for code extension`() {
+        assertTrue(FileTypeSupport.isSupported("kt"))
+        assertTrue(FileTypeSupport.isSupported("py"))
+        assertTrue(FileTypeSupport.isSupported("ts"))
+    }
+
+    @Test
+    fun `isSupported returns true for document extension`() {
+        assertTrue(FileTypeSupport.isSupported("pdf"))
+        assertTrue(FileTypeSupport.isSupported("docx"))
+        assertTrue(FileTypeSupport.isSupported("xlsx"))
+    }
+
+    @Test
+    fun `isSupported accepts extension with leading dot`() {
+        assertTrue(FileTypeSupport.isSupported(".jpg"))
+        assertTrue(FileTypeSupport.isSupported(".kt"))
+        assertTrue(FileTypeSupport.isSupported(".pdf"))
+    }
+
+    @Test
+    fun `isSupported is case insensitive`() {
+        assertTrue(FileTypeSupport.isSupported("PDF"))
+        assertTrue(FileTypeSupport.isSupported("JPG"))
+        assertTrue(FileTypeSupport.isSupported("KT"))
+    }
+
+    @Test
+    fun `isSupported returns false for unknown extension`() {
+        assertFalse(FileTypeSupport.isSupported("exe"))
+        assertFalse(FileTypeSupport.isSupported("dll"))
+        assertFalse(FileTypeSupport.isSupported("mp4"))
+        assertFalse(FileTypeSupport.isSupported("zip"))
+    }
+
+    @Test
+    fun `isSupported returns false for empty string`() {
+        assertFalse(FileTypeSupport.isSupported(""))
+    }
+
+    @Test
+    fun `ALL_SUPPORTED_EXTENSIONS contains every TEXT_EXTENSIONS entry`() {
+        assertTrue(FileTypeSupport.ALL_SUPPORTED_EXTENSIONS.containsAll(FileTypeSupport.TEXT_EXTENSIONS))
+    }
+
+    @Test
+    fun `ALL_SUPPORTED_EXTENSIONS contains every CODE_EXTENSIONS entry`() {
+        assertTrue(FileTypeSupport.ALL_SUPPORTED_EXTENSIONS.containsAll(FileTypeSupport.CODE_EXTENSIONS))
+    }
+
+    @Test
+    fun `ALL_SUPPORTED_EXTENSIONS contains every DOCUMENT_EXTENSIONS entry`() {
+        assertTrue(FileTypeSupport.ALL_SUPPORTED_EXTENSIONS.containsAll(FileTypeSupport.DOCUMENT_EXTENSIONS))
+    }
+
+    @Test
+    fun `ALL_SUPPORTED_EXTENSIONS contains every IMAGE_EXTENSIONS entry`() {
+        assertTrue(FileTypeSupport.ALL_SUPPORTED_EXTENSIONS.containsAll(FileTypeSupport.IMAGE_EXTENSIONS))
+    }
+
+    // ============================================================================
+    // isConfigFile – CONFIG_EXTENSIONS
+    // ============================================================================
+
+    @Test
+    fun `isConfigFile returns true for Dockerfile`() {
+        assertTrue(FileTypeSupport.isConfigFile("Dockerfile"))
+    }
+
+    @Test
+    fun `isConfigFile returns true for Makefile`() {
+        assertTrue(FileTypeSupport.isConfigFile("Makefile"))
+    }
+
+    @Test
+    fun `isConfigFile returns true for Jenkinsfile`() {
+        assertTrue(FileTypeSupport.isConfigFile("Jenkinsfile"))
+    }
+
+    @Test
+    fun `isConfigFile returns true for Procfile`() {
+        assertTrue(FileTypeSupport.isConfigFile("Procfile"))
+    }
+
+    @Test
+    fun `isConfigFile returns true for Vagrantfile`() {
+        assertTrue(FileTypeSupport.isConfigFile("Vagrantfile"))
+    }
+
+    @Test
+    fun `isConfigFile returns true for Gemfile`() {
+        assertTrue(FileTypeSupport.isConfigFile("Gemfile"))
+    }
+
+    @Test
+    fun `isConfigFile is case insensitive`() {
+        assertTrue(FileTypeSupport.isConfigFile("dockerfile"))
+        assertTrue(FileTypeSupport.isConfigFile("MAKEFILE"))
+        assertTrue(FileTypeSupport.isConfigFile("Gemfile"))
+    }
+
+    @Test
+    fun `isConfigFile returns false for file with extension`() {
+        assertFalse(FileTypeSupport.isConfigFile("docker-compose.yml"))
+        assertFalse(FileTypeSupport.isConfigFile("Makefile.am"))
+    }
+
+    @Test
+    fun `isConfigFile returns false for unknown extensionless file`() {
+        assertFalse(FileTypeSupport.isConfigFile("RandomFile"))
+        assertFalse(FileTypeSupport.isConfigFile("NOTICE"))
+    }
+
+    @Test
+    fun `isConfigFile returns false for empty string`() {
+        assertFalse(FileTypeSupport.isConfigFile(""))
+    }
+
     @Test
     fun `test config files without extensions`() {
         assertTrue("dockerfile" in FileTypeSupport.CONFIG_EXTENSIONS)
@@ -60,4 +485,11 @@ class FileTypeSupportTest {
         assertTrue("gemfile" in FileTypeSupport.CONFIG_EXTENSIONS)
         assertFalse("randomfile" in FileTypeSupport.CONFIG_EXTENSIONS)
     }
+
+    @Test
+    fun `getExtension returns empty string for all CONFIG_EXTENSIONS entries`() {
+        FileTypeSupport.CONFIG_EXTENSIONS.forEach { name ->
+            assertEquals("", FileTypeSupport.getExtension(name), "Expected no extension for config file: $name")
+        }
+    }
 }