diff --git a/oxlint-plugin-t3code/package.json b/oxlint-plugin-t3code/package.json
index dbcd2c510f08..23af23738169 100644
--- a/oxlint-plugin-t3code/package.json
+++ b/oxlint-plugin-t3code/package.json
@@ -14,6 +14,7 @@
   "devDependencies": {
     "@effect/language-service": "catalog:",
     "@effect/vitest": "catalog:",
+    "@t3tools/shared": "workspace:*",
     "@types/bun": "catalog:",
     "typescript": "catalog:",
     "vite-plus": "catalog:",
diff --git a/oxlint-plugin-t3code/test/utils.ts b/oxlint-plugin-t3code/test/utils.ts
index eb91d32d7d46..086d8d814ff8 100644
--- a/oxlint-plugin-t3code/test/utils.ts
+++ b/oxlint-plugin-t3code/test/utils.ts
@@ -1,4 +1,5 @@
 import * as NodeServices from "@effect/platform-node/NodeServices";
+import { resolveWindowsSpawn } from "@t3tools/shared/shell";
 import { assert, it } from "@effect/vitest";
 import * as Data from "effect/Data";
 import * as Effect from "effect/Effect";
@@ -112,8 +113,12 @@ export const createOxlintRuleHarness = (
     );
     yield* fs.writeFileString(sourcePath, source);
 
+    const spawn = resolveWindowsSpawn(oxlintBin);
     const output = yield* spawnAndCollectOutput(
-      ChildProcess.make(oxlintBin, ["--config", configPath, sourcePath], { cwd: repoRoot }),
+      ChildProcess.make(spawn.command, ["--config", configPath, sourcePath], {
+        cwd: repoRoot,
+        shell: spawn.shell,
+      }),
     );
 
     if (output.exitCode !== 0) {
diff --git a/packages/effect-acp/package.json b/packages/effect-acp/package.json
index 830c4aa45158..be64a6e58bbd 100644
--- a/packages/effect-acp/package.json
+++ b/packages/effect-acp/package.json
@@ -45,6 +45,7 @@
     "@effect/openapi-generator": "catalog:",
     "@effect/platform-node": "catalog:",
     "@effect/vitest": "catalog:",
+    "@t3tools/shared": "workspace:*",
     "@types/node": "catalog:",
     "typescript": "catalog:",
     "vite-plus": "catalog:",
diff --git a/packages/effect-acp/src/client.test.ts b/packages/effect-acp/src/client.test.ts
index b867231ad7eb..04a5568e5349 100644
--- a/packages/effect-acp/src/client.test.ts
+++ b/packages/effect-acp/src/client.test.ts
@@ -12,6 +12,7 @@ import * as Stream from "effect/Stream";
 import { ChildProcess, ChildProcessSpawner } from "effect/unstable/process";
 
 import * as NodeServices from "@effect/platform-node/NodeServices";
+import { resolveWindowsSpawn } from "@t3tools/shared/shell";
 import { it, assert } from "@effect/vitest";
 
 import * as AcpClient from "./client.ts";
@@ -34,9 +35,10 @@ it.layer(NodeServices.layer)("effect-acp client", (it) => {
     Effect.gen(function* () {
       const spawner = yield* ChildProcessSpawner.ChildProcessSpawner;
       const path = yield* Path.Path;
-      const command = ChildProcess.make("bun", ["run", yield* mockPeerPath], {
+      const spawn = resolveWindowsSpawn("bun");
+      const command = ChildProcess.make(spawn.command, ["run", yield* mockPeerPath], {
         cwd: path.join(import.meta.dirname, ".."),
-        shell: process.platform === "win32",
+        shell: spawn.shell,
         ...(env ? { env: { ...process.env, ...env } } : {}),
       });
       return yield* spawner.spawn(command);
diff --git a/packages/effect-acp/src/protocol.test.ts b/packages/effect-acp/src/protocol.test.ts
index 392b61431e6e..96ce2634889c 100644
--- a/packages/effect-acp/src/protocol.test.ts
+++ b/packages/effect-acp/src/protocol.test.ts
@@ -11,6 +11,7 @@ import { ChildProcess, ChildProcessSpawner } from "effect/unstable/process";
 
 import { it, assert } from "@effect/vitest";
 import * as NodeServices from "@effect/platform-node/NodeServices";
+import { resolveWindowsSpawn } from "@t3tools/shared/shell";
 
 import * as AcpSchema from "./_generated/schema.gen.ts";
 import * as AcpProtocol from "./protocol.ts";
@@ -58,9 +59,10 @@ const makeHandle = (env?: Record<string, string>) =>
   Effect.gen(function* () {
     const spawner = yield* ChildProcessSpawner.ChildProcessSpawner;
     const path = yield* Path.Path;
-    const command = ChildProcess.make("bun", ["run", yield* mockPeerPath], {
+    const spawn = resolveWindowsSpawn("bun");
+    const command = ChildProcess.make(spawn.command, ["run", yield* mockPeerPath], {
       cwd: path.join(import.meta.dirname, ".."),
-      shell: process.platform === "win32",
+      shell: spawn.shell,
       ...(env ? { env: { ...process.env, ...env } } : {}),
     });
     return yield* spawner.spawn(command);
diff --git a/packages/effect-codex-app-server/package.json b/packages/effect-codex-app-server/package.json
index 7c8fa1d86251..798ce496fd94 100644
--- a/packages/effect-codex-app-server/package.json
+++ b/packages/effect-codex-app-server/package.json
@@ -38,6 +38,7 @@
     "@effect/openapi-generator": "catalog:",
     "@effect/platform-node": "catalog:",
     "@effect/vitest": "catalog:",
+    "@t3tools/shared": "workspace:*",
     "@types/node": "catalog:",
     "typescript": "catalog:",
     "vite-plus": "catalog:",
diff --git a/packages/effect-codex-app-server/src/client.test.ts b/packages/effect-codex-app-server/src/client.test.ts
index 0e0127b1a94f..8d1890a442e2 100644
--- a/packages/effect-codex-app-server/src/client.test.ts
+++ b/packages/effect-codex-app-server/src/client.test.ts
@@ -7,6 +7,7 @@ import * as Scope from "effect/Scope";
 import { ChildProcess, ChildProcessSpawner } from "effect/unstable/process";
 
 import * as NodeServices from "@effect/platform-node/NodeServices";
+import { resolveWindowsSpawn } from "@t3tools/shared/shell";
 import { assert, it } from "@effect/vitest";
 
 import * as CodexClient from "./client.ts";
@@ -20,9 +21,10 @@ it.layer(NodeServices.layer)("effect-codex-app-server client", (it) => {
     Effect.gen(function* () {
       const spawner = yield* ChildProcessSpawner.ChildProcessSpawner;
       const path = yield* Path.Path;
-      const command = ChildProcess.make("bun", ["run", yield* mockPeerPath], {
+      const spawn = resolveWindowsSpawn("bun");
+      const command = ChildProcess.make(spawn.command, ["run", yield* mockPeerPath], {
         cwd: path.join(import.meta.dirname, ".."),
-        shell: process.platform === "win32",
+        shell: spawn.shell,
       });
       return yield* spawner.spawn(command);
     });
@@ -126,10 +128,12 @@ it.layer(NodeServices.layer)("effect-codex-app-server client", (it) => {
     Effect.gen(function* () {
       const path = yield* Path.Path;
       const scope = yield* Scope.make();
+      const spawn = resolveWindowsSpawn("bun");
       const clientLayer = CodexClient.layerCommand({
-        command: "bun",
+        command: spawn.command,
         args: ["run", yield* mockPeerPath],
         cwd: path.join(import.meta.dirname, ".."),
+        shell: spawn.shell,
       });
       const context = yield* Layer.buildWithScope(clientLayer, scope);
 
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 4d1f5e68e9c5..0206eb497de7 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -651,6 +651,9 @@ importers:
       '@effect/vitest':
         specifier: 4.0.0-beta.78
         version: 4.0.0-beta.78(patch_hash=42b87cc47e70d74e62496e7a8261b3fd298ecad4464d209348ab04b96f853a5f)(effect@4.0.0-beta.78(patch_hash=c502bc684210b707dfceb87d8fe6ad6843395af6e19cfc02cd65854898bde2c5))
+      '@t3tools/shared':
+        specifier: workspace:*
+        version: link:../packages/shared
       '@types/bun':
         specifier: 'catalog:'
         version: 1.3.14
@@ -735,6 +738,9 @@ importers:
       '@effect/vitest':
         specifier: 4.0.0-beta.78
         version: 4.0.0-beta.78(patch_hash=42b87cc47e70d74e62496e7a8261b3fd298ecad4464d209348ab04b96f853a5f)(effect@4.0.0-beta.78(patch_hash=c502bc684210b707dfceb87d8fe6ad6843395af6e19cfc02cd65854898bde2c5))
+      '@t3tools/shared':
+        specifier: workspace:*
+        version: link:../shared
       '@types/node':
         specifier: ^24.10.13
         version: 24.13.2
@@ -766,6 +772,9 @@ importers:
       '@effect/vitest':
         specifier: 4.0.0-beta.78
         version: 4.0.0-beta.78(patch_hash=42b87cc47e70d74e62496e7a8261b3fd298ecad4464d209348ab04b96f853a5f)(effect@4.0.0-beta.78(patch_hash=c502bc684210b707dfceb87d8fe6ad6843395af6e19cfc02cd65854898bde2c5))
+      '@t3tools/shared':
+        specifier: workspace:*
+        version: link:../shared
       '@types/node':
         specifier: ^24.10.13
         version: 24.13.2