diff --git a/src/infra/exec-wrapper-resolution.test.ts b/src/infra/exec-wrapper-resolution.test.ts
index b271c97ee8d..58f1e696c22 100644
--- a/src/infra/exec-wrapper-resolution.test.ts
+++ b/src/infra/exec-wrapper-resolution.test.ts
@@ -1,16 +1,68 @@
 import { describe, expect, test } from "vitest";
-import { normalizeExecutableToken } from "./exec-wrapper-resolution.js";
+import {
+  basenameLower,
+  isDispatchWrapperExecutable,
+  isShellWrapperExecutable,
+  normalizeExecutableToken,
+  unwrapKnownShellMultiplexerInvocation,
+} from "./exec-wrapper-resolution.js";
 
-describe("normalizeExecutableToken", () => {
-  test("strips common windows executable suffixes", () => {
-    expect(normalizeExecutableToken("bun.cmd")).toBe("bun");
-    expect(normalizeExecutableToken("deno.bat")).toBe("deno");
-    expect(normalizeExecutableToken("pwsh.com")).toBe("pwsh");
-    expect(normalizeExecutableToken("cmd.exe")).toBe("cmd");
-  });
-
-  test("normalizes path-qualified windows shims", () => {
-    expect(normalizeExecutableToken("C:\\tools\\bun.cmd")).toBe("bun");
-    expect(normalizeExecutableToken("/tmp/deno.exe")).toBe("deno");
+describe("basenameLower", () => {
+  test.each([
+    { token: " Bun.CMD ", expected: "bun.cmd" },
+    { token: "C:\\tools\\PwSh.EXE", expected: "pwsh.exe" },
+    { token: "/tmp/bash", expected: "bash" },
+  ])("normalizes basenames for %j", ({ token, expected }) => {
+    expect(basenameLower(token)).toBe(expected);
+  });
+});
+
+describe("normalizeExecutableToken", () => {
+  test.each([
+    { token: "bun.cmd", expected: "bun" },
+    { token: "deno.bat", expected: "deno" },
+    { token: "pwsh.com", expected: "pwsh" },
+    { token: "cmd.exe", expected: "cmd" },
+    { token: "C:\\tools\\bun.cmd", expected: "bun" },
+    { token: "/tmp/deno.exe", expected: "deno" },
+    { token: " /tmp/bash ", expected: "bash" },
+  ])("normalizes executable tokens for %j", ({ token, expected }) => {
+    expect(normalizeExecutableToken(token)).toBe(expected);
+  });
+});
+
+describe("wrapper classification", () => {
+  test.each([
+    { token: "sudo", dispatch: true, shell: false },
+    { token: "timeout.exe", dispatch: true, shell: false },
+    { token: "bash", dispatch: false, shell: true },
+    { token: "pwsh.exe", dispatch: false, shell: true },
+    { token: "node", dispatch: false, shell: false },
+  ])("classifies wrappers for %j", ({ token, dispatch, shell }) => {
+    expect(isDispatchWrapperExecutable(token)).toBe(dispatch);
+    expect(isShellWrapperExecutable(token)).toBe(shell);
+  });
+});
+
+describe("unwrapKnownShellMultiplexerInvocation", () => {
+  test.each([
+    { argv: [], expected: { kind: "not-wrapper" } },
+    { argv: ["node", "-e", "1"], expected: { kind: "not-wrapper" } },
+    { argv: ["busybox"], expected: { kind: "blocked", wrapper: "busybox" } },
+    { argv: ["busybox", "ls"], expected: { kind: "blocked", wrapper: "busybox" } },
+    {
+      argv: ["busybox", "sh", "-lc", "echo hi"],
+      expected: { kind: "unwrapped", wrapper: "busybox", argv: ["sh", "-lc", "echo hi"] },
+    },
+    {
+      argv: ["toybox", "--", "pwsh.exe", "-Command", "Get-Date"],
+      expected: {
+        kind: "unwrapped",
+        wrapper: "toybox",
+        argv: ["pwsh.exe", "-Command", "Get-Date"],
+      },
+    },
+  ])("unwraps shell multiplexers for %j", ({ argv, expected }) => {
+    expect(unwrapKnownShellMultiplexerInvocation(argv)).toEqual(expected);
   });
 });