fix(tui): highlight Containerfile, Dockerfile.*, and shell dotfiles

packages/tui/src/highlight.ts

@@ -55,11 +55,18 @@ const LANGUAGE_ALIASES: Readonly<Record<string, string>> = {
 
 const FILE_LANGUAGES: Readonly<Record<string, string>> = {
   dockerfile: "dockerfile",
+  containerfile: "dockerfile",
   makefile: "makefile",
+  gnumakefile: "makefile",
   cmakelists: "cmake",
   "cmakelists.txt": "cmake",
   gemfile: "ruby",
   rakefile: "ruby",
+  vagrantfile: "ruby",
+  ".bashrc": "bash",
+  ".zshrc": "bash",
+  ".bash_profile": "bash",
+  ".profile": "bash",
 };
 
 function languageName(language: string | undefined): string | undefined {
@@ -75,6 +82,11 @@ export function languageForPath(path: string): string | undefined {
   const name = path.split(/[\\/]/u).at(-1)?.toLowerCase() ?? "";
   const named = FILE_LANGUAGES[name];
   if (named !== undefined) return named;
+  // Dockerfile.* / Containerfile.* keep dockerfile highlighting even when the
+  // "extension" is an environment name (dev, prod, …) that is not a language.
+  if (name.startsWith("dockerfile.") || name.startsWith("containerfile.")) {
+    return "dockerfile";
+  }
   const extension = name.includes(".") ? name.slice(name.lastIndexOf(".") + 1) : "";
   return languageName(extension);
 }

packages/tui/test/highlight.test.ts

@@ -0,0 +1,49 @@
+// SPDX-FileCopyrightText: 2026 Kaushik Kumar
+// SPDX-License-Identifier: Apache-2.0
+
+import assert from "node:assert/strict";
+import test from "node:test";
+import { languageForPath } from "../src/highlight.ts";
+
+test("languageForPath maps exact file names", () => {
+  const cases: Array<[string, string | undefined]> = [
+    ["Dockerfile", "dockerfile"],
+    ["Containerfile", "dockerfile"],
+    ["Makefile", "makefile"],
+    ["GNUmakefile", "makefile"],
+    ["CMakeLists.txt", "cmake"],
+    ["Gemfile", "ruby"],
+    ["Rakefile", "ruby"],
+    ["Vagrantfile", "ruby"],
+    [".bashrc", "bash"],
+    [".zshrc", "bash"],
+    [".bash_profile", "bash"],
+    [".profile", "bash"],
+  ];
+  for (const [path, expected] of cases) {
+    assert.equal(languageForPath(path), expected, path);
+  }
+});
+
+test("languageForPath maps Dockerfile.* and Containerfile.* prefixes", () => {
+  assert.equal(languageForPath("Dockerfile.dev"), "dockerfile");
+  assert.equal(languageForPath("Dockerfile.prod"), "dockerfile");
+  assert.equal(languageForPath("Containerfile.local"), "dockerfile");
+});
+
+test("languageForPath maps common extensions", () => {
+  assert.equal(languageForPath("src/app.ts"), "typescript");
+  assert.equal(languageForPath("main.py"), "python");
+  assert.equal(languageForPath("lib.rs"), "rust");
+});
+
+test("languageForPath is case-insensitive and accepts Windows paths", () => {
+  assert.equal(languageForPath("C:\\repo\\Dockerfile"), "dockerfile");
+  assert.equal(languageForPath("C:\\repo\\Containerfile"), "dockerfile");
+  assert.equal(languageForPath("packages\\TUI\\App.TS"), "typescript");
+});
+
+test("languageForPath returns undefined for unknown names", () => {
+  assert.equal(languageForPath("notes"), undefined);
+  assert.equal(languageForPath("archive.zzz"), undefined);
+});