diff --git a/src/server/__tests__/e2e/business-flow.test.ts b/src/server/__tests__/e2e/business-flow.test.ts
index 636ac073..b26b6ffa 100644
--- a/src/server/__tests__/e2e/business-flow.test.ts
+++ b/src/server/__tests__/e2e/business-flow.test.ts
@@ -20,7 +20,25 @@ const originalCliPath = process.env.CLAUDE_CLI_PATH
 const originalDisableTerminalShellEnv = process.env.CC_HAHA_DISABLE_TERMINAL_SHELL_ENV
 const mockSdkCliPath = fileURLToPath(new URL('../fixtures/mock-sdk-cli.ts', import.meta.url))
 
+// The models API derives its model list from these env vars (see
+// src/server/api/models.ts getEnvConfiguredAnthropicModels). A developer who
+// exports them for a custom provider would otherwise leak them into the
+// no-provider fixture and break the default-model assertions. Isolate them.
+const MODEL_ENV_KEYS = [
+  'ANTHROPIC_MODEL',
+  'ANTHROPIC_DEFAULT_HAIKU_MODEL',
+  'ANTHROPIC_DEFAULT_SONNET_MODEL',
+  'ANTHROPIC_DEFAULT_OPUS_MODEL',
+] as const
+const originalModelEnv = Object.fromEntries(
+  MODEL_ENV_KEYS.map((key) => [key, process.env[key]]),
+) as Record<(typeof MODEL_ENV_KEYS)[number], string | undefined>
+
 function restoreEnv() {
+  for (const key of MODEL_ENV_KEYS) {
+    if (originalModelEnv[key] !== undefined) process.env[key] = originalModelEnv[key]
+    else delete process.env[key]
+  }
   if (originalConfigDir !== undefined) {
     process.env.CLAUDE_CONFIG_DIR = originalConfigDir
   } else {
@@ -47,6 +65,7 @@ async function startTestServer() {
   process.env.CLAUDE_CONFIG_DIR = tmpDir
   process.env.CLAUDE_CLI_PATH = mockSdkCliPath
   process.env.CC_HAHA_DISABLE_TERMINAL_SHELL_ENV = '1'
+  for (const key of MODEL_ENV_KEYS) delete process.env[key]
   await fs.mkdir(path.join(tmpDir, 'projects'), { recursive: true })
   await fs.mkdir(path.join(tmpDir, 'agents'), { recursive: true })
 
diff --git a/src/server/__tests__/e2e/full-flow.test.ts b/src/server/__tests__/e2e/full-flow.test.ts
index 89e4200e..7d48965a 100644
--- a/src/server/__tests__/e2e/full-flow.test.ts
+++ b/src/server/__tests__/e2e/full-flow.test.ts
@@ -18,7 +18,25 @@ const originalCliPath = process.env.CLAUDE_CLI_PATH
 const originalDisableTerminalShellEnv = process.env.CC_HAHA_DISABLE_TERMINAL_SHELL_ENV
 const mockSdkCliPath = fileURLToPath(new URL('../fixtures/mock-sdk-cli.ts', import.meta.url))
 
+// The models API derives its model list from these env vars (see
+// src/server/api/models.ts getEnvConfiguredAnthropicModels). A developer who
+// exports them for a custom provider would otherwise leak them into the
+// no-provider fixture and break the default-model assertions. Isolate them.
+const MODEL_ENV_KEYS = [
+  'ANTHROPIC_MODEL',
+  'ANTHROPIC_DEFAULT_HAIKU_MODEL',
+  'ANTHROPIC_DEFAULT_SONNET_MODEL',
+  'ANTHROPIC_DEFAULT_OPUS_MODEL',
+] as const
+const originalModelEnv = Object.fromEntries(
+  MODEL_ENV_KEYS.map((key) => [key, process.env[key]]),
+) as Record<(typeof MODEL_ENV_KEYS)[number], string | undefined>
+
 function restoreEnv() {
+  for (const key of MODEL_ENV_KEYS) {
+    if (originalModelEnv[key] !== undefined) process.env[key] = originalModelEnv[key]
+    else delete process.env[key]
+  }
   if (originalConfigDir !== undefined) {
     process.env.CLAUDE_CONFIG_DIR = originalConfigDir
   } else {
@@ -46,6 +64,7 @@ async function startTestServer() {
   process.env.CLAUDE_CONFIG_DIR = tmpDir
   process.env.CLAUDE_CLI_PATH = mockSdkCliPath
   process.env.CC_HAHA_DISABLE_TERMINAL_SHELL_ENV = '1'
+  for (const key of MODEL_ENV_KEYS) delete process.env[key]
 
   // Create required directories
   await fs.mkdir(path.join(tmpDir, 'projects'), { recursive: true })