diff --git a/test/vitest/vitest.cli-process.config.ts b/test/vitest/vitest.cli-process.config.ts
index 47da79d9fdb2..24405e2f2284 100644
--- a/test/vitest/vitest.cli-process.config.ts
+++ b/test/vitest/vitest.cli-process.config.ts
@@ -1,9 +1,12 @@
+import type { ViteUserConfig } from "vitest/config";
 import { cliProcessTestFiles } from "./vitest.cli-process-paths.mjs";
 // CLI process tests run serially in isolated forks so child startup deadlines
 // measure the CLI rather than contention from the shared CLI test graph.
 import { createScopedVitestConfig } from "./vitest.scoped-config.ts";
 
-export function createCliProcessVitestConfig(env?: Record<string, string | undefined>) {
+export function createCliProcessVitestConfig(
+  env?: Record<string, string | undefined>,
+): ViteUserConfig {
   const config = createScopedVitestConfig(cliProcessTestFiles, {
     env,
     fileParallelism: false,
diff --git a/test/vitest/vitest.extension-config.ts b/test/vitest/vitest.extension-config.ts
index a2764bc63fda..e252a3a4c8f7 100644
--- a/test/vitest/vitest.extension-config.ts
+++ b/test/vitest/vitest.extension-config.ts
@@ -1,4 +1,5 @@
 // Vitest extension config helpers keep extension shard defaults aligned.
+import type { ViteUserConfig } from "vitest/config";
 import { loadPatternListFromEnv } from "./vitest.pattern-file.ts";
 import { createScopedVitestConfig } from "./vitest.scoped-config.ts";
 
@@ -13,7 +14,7 @@ export function createExtensionVitestConfig(
   testRoots: readonly string[],
   env: Record<string, string | undefined> = process.env,
   options: ExtensionVitestConfigOptions = {},
-) {
+): ViteUserConfig {
   return createScopedVitestConfig(
     loadPatternListFromEnv("OPENCLAW_VITEST_INCLUDE_FILE", env) ??
       testRoots.map((root) => `${root}/**/*.test.ts`),
diff --git a/test/vitest/vitest.extension-provider-openai.config.ts b/test/vitest/vitest.extension-provider-openai.config.ts
index 849d0dbe6690..544e1f70090f 100644
--- a/test/vitest/vitest.extension-provider-openai.config.ts
+++ b/test/vitest/vitest.extension-provider-openai.config.ts
@@ -1,12 +1,13 @@
-// Vitest extension provider openai config wires the extension provider openai test shard.
 import path from "node:path";
+// Vitest extension provider openai config wires the extension provider openai test shard.
+import type { ViteUserConfig } from "vitest/config";
 import { createExtensionVitestConfig } from "./vitest.extension-config.ts";
 import { providerOpenAiExtensionTestRoots } from "./vitest.extension-provider-paths.mjs";
 import { repoRoot } from "./vitest.shared.config.ts";
 
 export function createExtensionProviderOpenAiVitestConfig(
   env: Record<string, string | undefined> = process.env,
-) {
+): ViteUserConfig {
   const config = createExtensionVitestConfig(
     "provider-openai",
     providerOpenAiExtensionTestRoots,
diff --git a/test/vitest/vitest.process.config.ts b/test/vitest/vitest.process.config.ts
index 4a122d597bd9..b66651df1535 100644
--- a/test/vitest/vitest.process.config.ts
+++ b/test/vitest/vitest.process.config.ts
@@ -1,7 +1,10 @@
 // Vitest process config wires the process test shard.
+import type { ViteUserConfig } from "vitest/config";
 import { createScopedVitestConfig } from "./vitest.scoped-config.ts";
 
-export function createProcessVitestConfig(env?: Record<string, string | undefined>) {
+export function createProcessVitestConfig(
+  env?: Record<string, string | undefined>,
+): ViteUserConfig {
   const config = createScopedVitestConfig(["src/process/**/*.test.ts"], {
     dir: "src",
     env,
diff --git a/test/vitest/vitest.runtime-config.config.ts b/test/vitest/vitest.runtime-config.config.ts
index c96900c064d3..afa23924274c 100644
--- a/test/vitest/vitest.runtime-config.config.ts
+++ b/test/vitest/vitest.runtime-config.config.ts
@@ -1,7 +1,10 @@
 // Vitest runtime config config wires the runtime config test shard.
+import type { ViteUserConfig } from "vitest/config";
 import { createScopedVitestConfig } from "./vitest.scoped-config.ts";
 
-export function createRuntimeConfigVitestConfig(env?: Record<string, string | undefined>) {
+export function createRuntimeConfigVitestConfig(
+  env?: Record<string, string | undefined>,
+): ViteUserConfig {
   const config = createScopedVitestConfig(["src/config/**/*.test.ts"], {
     dir: "src",
     env,
diff --git a/test/vitest/vitest.scoped-config.ts b/test/vitest/vitest.scoped-config.ts
index 63bf5ce17678..638b05fa6a97 100644
--- a/test/vitest/vitest.scoped-config.ts
+++ b/test/vitest/vitest.scoped-config.ts
@@ -1,6 +1,6 @@
 // Vitest scoped config helper builds test configs for scoped file patterns.
 import path from "node:path";
-import { defineConfig } from "vitest/config";
+import { defineConfig, type ViteUserConfig } from "vitest/config";
 import {
   intersectIncludePatterns,
   loadPatternListFromEnv,
@@ -219,7 +219,9 @@ export function createScopedVitestConfig(
     setupFiles?: string[];
     useNonIsolatedRunner?: boolean;
   },
-) {
+  // Explicit nameable return type: inference otherwise reaches vite-internal
+  // names (TS4058/TS4082) in every downstream scoped-config creator.
+): ViteUserConfig {
   const base = sharedVitestConfig as Record<string, unknown>;
   const baseTest = sharedVitestConfig.test ?? {};
   const baseSequence = (baseTest as { sequence?: { groupOrder?: number } }).sequence;
diff --git a/test/vitest/vitest.ui-isolated.config.ts b/test/vitest/vitest.ui-isolated.config.ts
index f3ef7a776527..15acbeb1776a 100644
--- a/test/vitest/vitest.ui-isolated.config.ts
+++ b/test/vitest/vitest.ui-isolated.config.ts
@@ -2,12 +2,16 @@
 // The shared ui shard runs non-isolated for speed, but tests that spy on module
 // internals and assert the component uses that spy must not share a module cache
 // with stateful predecessor files (see uiIsolatedTestFiles).
+import type { ViteUserConfig } from "vitest/config";
 import { controlUiLocaleModulesPlugin } from "../../ui/config/control-ui-locales.ts";
 import { createScopedVitestConfig } from "./vitest.scoped-config.ts";
 import { jsdomOptimizedDeps } from "./vitest.shared.config.ts";
 import { uiIsolatedTestFiles } from "./vitest.ui-isolated-paths.mjs";
 
-export function createUiIsolatedVitestConfig(env?: Record<string, string | undefined>) {
+// Explicit nameable return type: inference reaches vite-internal names (TS4058/TS4082).
+export function createUiIsolatedVitestConfig(
+  env?: Record<string, string | undefined>,
+): ViteUserConfig {
   const config = createScopedVitestConfig(uiIsolatedTestFiles, {
     deps: jsdomOptimizedDeps,
     environment: "jsdom",
diff --git a/test/vitest/vitest.ui.config.ts b/test/vitest/vitest.ui.config.ts
index e2eee123450e..5f6505075247 100644
--- a/test/vitest/vitest.ui.config.ts
+++ b/test/vitest/vitest.ui.config.ts
@@ -1,13 +1,15 @@
 // Vitest ui config wires the ui test shard.
+import type { ViteUserConfig } from "vitest/config";
 import { controlUiLocaleModulesPlugin } from "../../ui/config/control-ui-locales.ts";
 import { createScopedVitestConfig } from "./vitest.scoped-config.ts";
 import { jsdomOptimizedDeps } from "./vitest.shared.config.ts";
 import { uiIsolatedTestFiles } from "./vitest.ui-isolated-paths.mjs";
 
+// Explicit nameable return type: inference reaches vite-internal names (TS4058/TS4082).
 export function createUiVitestConfig(
   env?: Record<string, string | undefined>,
   options?: { includePatterns?: string[]; name?: string },
-) {
+): ViteUserConfig {
   const includePatterns = options?.includePatterns ?? ["ui/src/**/*.test.ts"];
   // Isolated files must never enter the shared module graph, including scoped runs.
   const exclude = ["ui/src/**/*.e2e.test.ts", ...uiIsolatedTestFiles];