Use Match for CLI MIME detection

ts/packages/cli/src/__tests__/library.test.ts

@@ -0,0 +1,22 @@
+import { describe, expect, it } from "vitest";
+import { guessMimeType } from "../commands/library.js";
+
+describe("library CLI helpers", () => {
+  it("detects known MIME types through the Match-backed extension mapper", () => {
+    expect(guessMimeType("paper.pdf")).toBe("application/pdf");
+    expect(guessMimeType("notes.TXT")).toBe("text/plain");
+    expect(guessMimeType("readme.md")).toBe("text/markdown");
+    expect(guessMimeType("index.html")).toBe("text/html");
+    expect(guessMimeType("partial.htm")).toBe("text/html");
+    expect(guessMimeType("data.json")).toBe("application/json");
+    expect(guessMimeType("table.csv")).toBe("text/csv");
+    expect(guessMimeType("brief.docx")).toBe(
+      "application/vnd.openxmlformats-officedocument.wordprocessingml.document",
+    );
+  });
+
+  it("falls back for unknown or extensionless paths", () => {
+    expect(guessMimeType("archive.bin")).toBe("application/octet-stream");
+    expect(guessMimeType("README")).toBe("application/octet-stream");
+  });
+});

ts/packages/cli/src/commands/library.ts

@@ -5,7 +5,7 @@
  */
 
 import type { Command } from "commander";
-import { Effect } from "effect";
+import { Effect, Match } from "effect";
 import { cliCommandError, withSocket, writeJson } from "./util.js";
 
 function basenamePath(filepath: string): string {
@@ -15,27 +15,19 @@ function basenamePath(filepath: string): string {
 }
 
 /** Simple MIME-type lookup by file extension. */
-function guessMimeType(filepath: string): string {
+export function guessMimeType(filepath: string): string {
   const ext = filepath.split(".").pop()?.toLowerCase();
-  switch (ext) {
-    case "pdf":
-      return "application/pdf";
-    case "txt":
-      return "text/plain";
-    case "md":
-      return "text/markdown";
-    case "html":
-    case "htm":
-      return "text/html";
-    case "json":
-      return "application/json";
-    case "csv":
-      return "text/csv";
-    case "docx":
-      return "application/vnd.openxmlformats-officedocument.wordprocessingml.document";
-    default:
-      return "application/octet-stream";
-  }
+  return Match.value(ext).pipe(
+    Match.when("pdf", () => "application/pdf"),
+    Match.when("txt", () => "text/plain"),
+    Match.when("md", () => "text/markdown"),
+    Match.when("html", () => "text/html"),
+    Match.when("htm", () => "text/html"),
+    Match.when("json", () => "application/json"),
+    Match.when("csv", () => "text/csv"),
+    Match.when("docx", () => "application/vnd.openxmlformats-officedocument.wordprocessingml.document"),
+    Match.orElse(() => "application/octet-stream"),
+  );
 }
 
 export function registerLibraryCommands(program: Command): void {