Use Match for CLI MIME detection

ts/EFFECT_NATIVE_REWRITE_AUDIT.md

@@ -499,6 +499,21 @@ Notes:
   - `bun run --cwd ts/packages/flow test -- src/__tests__/agent-service.test.ts`
   - `cd ts && bun run check:tsgo`
 
+### 2026-06-04: CLI Library MIME Match Slice
+
+- Status: migrated and package-verified.
+- Completed:
+  - `ts/packages/cli/src/commands/library.ts` now uses `effect/Match` for
+    extension-to-MIME mapping instead of a native `switch`.
+  - `guessMimeType` is exported for focused CLI helper coverage.
+  - CLI tests now cover known extensions, case normalization, `html`/`htm`
+    aliases, and fallback behavior for unknown or extensionless paths.
+  - `ts/packages/cli/package.json` excludes `dist/**` from Vitest so built
+    test output is not executed a second time after root build lanes.
+- Verification:
+  - `bun run --cwd ts/packages/cli test -- src/__tests__/library.test.ts`
+  - `cd ts && bun run check:tsgo`
+
 ### 2026-06-02: RAG And Agent Requestor Bridge Slice
 
 - Status: migrated, root-verified, committed, and pushed.

ts/packages/cli/package.json

@@ -9,7 +9,7 @@
     "build": "bunx --bun tsc",
     "dev": "tsc --watch",
     "clean": "rm -rf dist",
-    "test": "bunx --bun vitest run --passWithNoTests"
+    "test": "bunx --bun vitest run --passWithNoTests --exclude=dist/**"
   },
   "dependencies": {
     "@trustgraph/base": "workspace:*",

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) {
+  return Match.value(ext).pipe(
-    case "pdf":
+    Match.when("pdf", () => "application/pdf"),
-      return "application/pdf";
+    Match.when("txt", () => "text/plain"),
-    case "txt":
+    Match.when("md", () => "text/markdown"),
-      return "text/plain";
+    Match.when("html", () => "text/html"),
-    case "md":
+    Match.when("htm", () => "text/html"),
-      return "text/markdown";
+    Match.when("json", () => "application/json"),
-    case "html":
+    Match.when("csv", () => "text/csv"),
-    case "htm":
+    Match.when("docx", () => "application/vnd.openxmlformats-officedocument.wordprocessingml.document"),
-      return "text/html";
+    Match.orElse(() => "application/octet-stream"),
-    case "json":
+  );
-      return "application/json";
-    case "csv":
-      return "text/csv";
-    case "docx":
-      return "application/vnd.openxmlformats-officedocument.wordprocessingml.document";
-    default:
-      return "application/octet-stream";
-  }
 }
 
 export function registerLibraryCommands(program: Command): void {