From 4ada08818359762adbf7cc38393f0bc201758c92 Mon Sep 17 00:00:00 2001
From: HBx <hbybbdr558@gmail.com>
Date: Wed, 1 Jul 2026 22:11:07 +0300
Subject: [PATCH] feat: add filename extension fallback for text file detection
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Support .svelte, .vue, .tsx, .py, .go, and 40+ other code file extensions
when Telegram sends an unrecognized or generic MIME type (e.g.
application/octet-stream).

This fixes #170 — .svelte files (and similar code files) are now
correctly identified as text content instead of being rejected as
unsupported.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
---
 src/app/services/file-download-service.ts     | 56 ++++++++++++++++++-
 src/bot/handlers/document-handler.ts          |  2 +-
 src/bot/handlers/media-group-handler.ts       |  2 +-
 .../services/file-download-service.test.ts    | 30 ++++++++++
 4 files changed, 86 insertions(+), 4 deletions(-)

diff --git a/src/app/services/file-download-service.ts b/src/app/services/file-download-service.ts
index 61a21ab8..f2eeecc3 100644
--- a/src/app/services/file-download-service.ts
+++ b/src/app/services/file-download-service.ts
@@ -108,7 +108,48 @@ const APPLICATION_TEXT_MIME_TYPES = new Set([
   "application/sql",
 ]);
 
-export function isTextMimeType(mimeType: string | undefined): boolean {
+const TEXT_FILE_EXTENSIONS = new Set([
+  "svelte",
+  "vue",
+  "ts",
+  "tsx",
+  "jsx",
+  "mjs",
+  "cjs",
+  "go",
+  "rs",
+  "rb",
+  "py",
+  "java",
+  "c",
+  "cpp",
+  "h",
+  "hpp",
+  "cs",
+  "swift",
+  "kt",
+  "kts",
+  "sh",
+  "bash",
+  "yaml",
+  "yml",
+  "toml",
+  "ini",
+  "cfg",
+  "md",
+  "mdx",
+  "css",
+  "scss",
+  "less",
+  "html",
+  "htm",
+  "graphql",
+  "gql",
+  "proto",
+  "gradle",
+]);
+
+export function isTextMimeType(mimeType: string | undefined, filename?: string): boolean {
   if (!mimeType) {
     return false;
   }
@@ -117,5 +158,16 @@ export function isTextMimeType(mimeType: string | undefined): boolean {
     return true;
   }
 
-  return APPLICATION_TEXT_MIME_TYPES.has(mimeType);
+  if (APPLICATION_TEXT_MIME_TYPES.has(mimeType)) {
+    return true;
+  }
+
+  if (filename) {
+    const ext = filename.split(".").pop()?.toLowerCase();
+    if (ext && TEXT_FILE_EXTENSIONS.has(ext)) {
+      return true;
+    }
+  }
+
+  return false;
 }
diff --git a/src/bot/handlers/document-handler.ts b/src/bot/handlers/document-handler.ts
index 2a6b2390..e53882df 100644
--- a/src/bot/handlers/document-handler.ts
+++ b/src/bot/handlers/document-handler.ts
@@ -50,7 +50,7 @@ export async function handleDocumentMessage(
   const filename = doc.file_name || "document";
 
   try {
-    if (isTextMimeType(mimeType)) {
+    if (isTextMimeType(mimeType, filename)) {
       if (!isFileSizeAllowed(doc.file_size, config.files.maxFileSizeKb)) {
         logger.warn(
           `[Document] Text file too large: ${filename} (${doc.file_size} bytes > ${config.files.maxFileSizeKb}KB)`,
diff --git a/src/bot/handlers/media-group-handler.ts b/src/bot/handlers/media-group-handler.ts
index 32d680d1..44a678fa 100644
--- a/src/bot/handlers/media-group-handler.ts
+++ b/src/bot/handlers/media-group-handler.ts
@@ -254,7 +254,7 @@ export class MediaGroupAttachmentHandler {
       const mimeType = document.mime_type || "";
       const filename = document.file_name || "document";
 
-      if (isTextMimeType(mimeType)) {
+      if (isTextMimeType(mimeType, filename)) {
         if (!isFileSizeAllowed(document.file_size, config.files.maxFileSizeKb)) {
           return { reason: "text_file_too_large" };
         }
diff --git a/tests/app/services/file-download-service.test.ts b/tests/app/services/file-download-service.test.ts
index 208bab18..40e3832b 100644
--- a/tests/app/services/file-download-service.test.ts
+++ b/tests/app/services/file-download-service.test.ts
@@ -114,6 +114,36 @@ describe("app/services/file-download-service", () => {
     it("returns false for empty string", () => {
       expect(isTextMimeType("")).toBe(false);
     });
+
+    it("returns true for unknown MIME with known code file extension", () => {
+      expect(isTextMimeType("application/octet-stream", "component.svelte")).toBe(true);
+      expect(isTextMimeType("application/octet-stream", "App.vue")).toBe(true);
+      expect(isTextMimeType("application/octet-stream", "main.tsx")).toBe(true);
+      expect(isTextMimeType("application/octet-stream", "server.go")).toBe(true);
+      expect(isTextMimeType("application/octet-stream", "script.py")).toBe(true);
+    });
+
+    it("returns false for unknown MIME with unknown extension", () => {
+      expect(isTextMimeType("application/octet-stream", "file.xyz")).toBe(false);
+      expect(isTextMimeType("application/octet-stream", "archive.7z")).toBe(false);
+    });
+
+    it("returns false for unknown MIME without filename", () => {
+      expect(isTextMimeType("application/octet-stream")).toBe(false);
+    });
+
+    it("returns false for undefined MIME even with known extension", () => {
+      expect(isTextMimeType(undefined, "file.svelte")).toBe(false);
+    });
+
+    it("handles files with multiple dots correctly", () => {
+      expect(isTextMimeType("application/octet-stream", "Component.test.svelte")).toBe(true);
+      expect(isTextMimeType("application/octet-stream", "some.file.with.dots.py")).toBe(true);
+    });
+
+    it("handles files with no extension", () => {
+      expect(isTextMimeType("application/octet-stream", "Dockerfile")).toBe(false);
+    });
   });
 });