diff --git a/.changeset/quiet-windows-rest.md b/.changeset/quiet-windows-rest.md
new file mode 100644
index 000000000..a845151cc
--- /dev/null
+++ b/.changeset/quiet-windows-rest.md
@@ -0,0 +1,2 @@
+---
+---
diff --git a/.github/workflows/pr-ci.yml b/.github/workflows/pr-ci.yml
index c8ae34947..0856dc7d8 100644
--- a/.github/workflows/pr-ci.yml
+++ b/.github/workflows/pr-ci.yml
@@ -94,8 +94,8 @@ jobs:
       - name: Theme contrast check
         run: bun run test:theme-contrast
 
-      - name: Test suite
-        run: bun run test
+      - name: Windows platform test suite
+        run: bun run test:windows
 
   compiled-headless-portability:
     name: Compiled headless portability (${{ matrix.os }})
diff --git a/package.json b/package.json
index 3e596a316..75d5d3eda 100644
--- a/package.json
+++ b/package.json
@@ -39,6 +39,7 @@
     "release:version": "bun run ./scripts/release/changeset-version.ts",
     "prepare": "simple-git-hooks",
     "test": "bun run ./scripts/test/run-test-suite.ts",
+    "test:windows": "bun run ./scripts/test/run-test-suite.ts --group=windows && bun run ./scripts/test/run-test-suite.ts --group=windows-ui",
     "test:theme-contrast": "bun test packages/hunk/src/ui/themes.test.ts --test-name-pattern contrast",
     "test:integration": "bun run ./scripts/test/run-test-suite.ts --group=integration",
     "test:session-broker-node": "bun run ./scripts/test/test-session-broker-node.ts",
diff --git a/scripts/test/run-test-suite.test.ts b/scripts/test/run-test-suite.test.ts
index fba05335f..68a4a772c 100644
--- a/scripts/test/run-test-suite.test.ts
+++ b/scripts/test/run-test-suite.test.ts
@@ -55,6 +55,16 @@ describe("test suite sharding", () => {
       group: "integration",
       patterns: TEST_PATTERN_GROUPS.integration,
     });
+    expect(resolveTestInvocation(["--group=windows", "--rerun-each=2"])).toEqual({
+      forwardedArgs: ["--path-ignore-patterns=**/packages/hunk/src/ui/**", "--rerun-each=2"],
+      group: "windows",
+      patterns: TEST_PATTERN_GROUPS.windows,
+    });
+    expect(resolveTestInvocation(["--group=windows-ui"])).toEqual({
+      forwardedArgs: [],
+      group: "windows-ui",
+      patterns: TEST_PATTERN_GROUPS["windows-ui"],
+    });
     expect(resolveTestInvocation([]).group).toBe("default");
     expect(() => resolveTestInvocation(["--group=missing"])).toThrow("Unknown test group: missing");
     expect(() => resolveTestInvocation(["--group=toString"])).toThrow(
diff --git a/scripts/test/run-test-suite.ts b/scripts/test/run-test-suite.ts
index c010716f3..816812554 100644
--- a/scripts/test/run-test-suite.ts
+++ b/scripts/test/run-test-suite.ts
@@ -16,11 +16,22 @@ import { availableParallelism } from "node:os";
 export const TEST_PATTERN_GROUPS = {
   default: ["./packages", "./scripts", "./examples", "./test/cli", "./test/session"],
   integration: ["./test/pty"],
+  windows: ["./packages", "./scripts", "./examples", "./test/cli", "./test/session"],
+  "windows-ui": [
+    "./packages/hunk/src/ui/diff/worker/highlightWorkerClient.test.ts",
+    "./packages/hunk/src/ui/lib/openInEditor.test.ts",
+    "./packages/hunk/src/ui/lib/workspaceWriteGuard.test.ts",
+  ],
 } as const;
 
 export const DEFAULT_TEST_PATTERNS = TEST_PATTERN_GROUPS.default;
 export type TestPatternGroup = keyof typeof TEST_PATTERN_GROUPS;
 
+const TEST_GROUP_RUNNER_ARGS: Partial<Record<TestPatternGroup, readonly string[]>> = {
+  // Linux covers terminal UI semantics; Windows runs its focused UI boundaries separately.
+  windows: ["--path-ignore-patterns=**/packages/hunk/src/ui/**"],
+};
+
 const MAX_AUTOMATIC_TEST_SHARDS = 2;
 const MAX_EXPLICIT_TEST_SHARDS = 64;
 const SHARD_TERMINATION_GRACE_MS = 1_000;
@@ -74,7 +85,10 @@ export function resolveTestInvocation(args: string[]) {
   }
 
   return {
-    forwardedArgs: args.filter((arg) => !arg.startsWith("--group=")),
+    forwardedArgs: [
+      ...(TEST_GROUP_RUNNER_ARGS[group] ?? []),
+      ...args.filter((arg) => !arg.startsWith("--group=")),
+    ],
     group,
     patterns: TEST_PATTERN_GROUPS[group],
   };
diff --git a/test/README.md b/test/README.md
index b25a0844e..9cba1f02e 100644
--- a/test/README.md
+++ b/test/README.md
@@ -36,6 +36,7 @@ test/
 | Command                              | Coverage                                                                                                               |
 | ------------------------------------ | ---------------------------------------------------------------------------------------------------------------------- |
 | `bun run test`                       | `packages/`, `scripts/`, `examples/`, `test/cli/`, and `test/session/`, as defined by `scripts/test/run-test-suite.ts` |
+| `bun run test:windows`               | Windows platform, process, VCS, CLI, and packaging coverage; Linux owns the terminal UI semantic suite                 |
 | `bun test ./test/review-conformance` | Shared review fixtures and registered consumer projections                                                             |
 | `bun run test:session-broker-node`   | Real Node listener/adapter conformance using the checked-in cross-runtime fixtures                                     |
 | `bun run test:integration`           | PTY-backed tests under `test/pty/`                                                                                     |
@@ -46,3 +47,7 @@ test/
 The dedicated trees are not selected directly by `bun run test`, though package tests import some
 shared runtime fixtures. Run the commands that match the changed behavior; omission from the default
 suite does not mean another command covers it.
+
+The Windows suite omits the platform-neutral terminal UI semantic tree, which the Linux suite covers,
+then runs the focused UI tests for worker startup, editor commands, and workspace path safety. Add new
+UI tests to the `windows-ui` group when their behavior depends on Windows platform boundaries.