Highlight Elixir and Erlang files in the file editor

Packages/Shared/CmuxSyntaxHighlighting/Sources/CmuxSyntaxHighlighting/LanguageCatalog.swift

@@ -43,6 +43,10 @@ public struct LanguageCatalog: Sendable {
         "go": "go",
         "rs": "rust",
         "rb": "ruby",
+        "ex": "elixir",
+        "exs": "elixir",
+        "erl": "erlang",
+        "hrl": "erlang",
         "java": "java",
         "kt": "kotlin",
         "kts": "kotlin",

Packages/Shared/CmuxSyntaxHighlighting/Tests/CmuxSyntaxHighlightingTests/LanguageCatalogTests.swift

@@ -16,6 +16,14 @@ struct LanguageCatalogTests {
         #expect(catalog.language(forExtension: ".py") == "python")
     }
 
+    @Test("Maps BEAM source extensions to highlight.js ids")
+    func mapsBeamExtensions() {
+        #expect(catalog.language(forExtension: "ex") == "elixir")
+        #expect(catalog.language(forExtension: "exs") == "elixir")
+        #expect(catalog.language(forExtension: "erl") == "erlang")
+        #expect(catalog.language(forExtension: "hrl") == "erlang")
+    }
+
     @Test("Unknown extensions return nil")
     func unknownExtensionIsNil() {
         #expect(catalog.language(forExtension: "bin") == nil)

Sources/Panels/FilePreviewPanel.swift

@@ -943,7 +943,8 @@ enum FilePreviewKindResolver {
 
     private static let textExtensions: Set<String> = [
         "bash", "c", "cc", "cfg", "conf", "cpp", "cs", "css", "csv", "cts", "env",
-        "fish", "go", "h", "hpp", "htm", "html", "ini", "java", "js", "json",
+        "erl", "ex", "exs", "fish", "go", "h", "hpp", "hrl", "htm", "html", "ini",
+        "java", "js", "json",
         "jsx", "kt", "log", "m", "markdown", "md", "mdx", "mm", "mts", "plist",
         "py", "rb", "rs", "sh", "sql", "swift", "toml", "ts", "tsx", "tsv", "txt",
         "xml", "yaml", "yml", "zsh"

cmuxTests/FilePreviewKindResolverTests.swift

@@ -26,6 +26,25 @@ struct FilePreviewKindResolverTests {
         }
     }
 
+    @Test("Elixir and Erlang source files route directly to text preview")
+    func beamSourceFilesRouteDirectlyToTextPreview() throws {
+        // .exs collides with the Logic sampler UTI (com.apple.logic.exs), which
+        // conforms to audiovisualContent and would otherwise open as media.
+        for fileExtension in ["ex", "exs", "erl", "hrl"] {
+            let url = try temporaryFile(
+                extension: fileExtension,
+                contents: "defmodule Greeter do\n  def hello, do: :world\nend\n"
+            )
+            defer { try? FileManager.default.removeItem(at: url) }
+
+            #expect(
+                FilePreviewKindResolver.initialMode(for: url) == .text,
+                "Expected .\(fileExtension) to avoid the QuickLook/media backend before async resolution."
+            )
+            #expect(FilePreviewKindResolver.mode(for: url) == .text)
+        }
+    }
+
     @Test("Movie file extensions keep media preview")
     func movieFileExtensionsKeepMediaPreview() throws {
         for fileExtension in ["mov", "mp4"] {