diff --git a/src/components/common/Settings/AI/apiKeyReuse.test.ts b/src/components/common/Settings/AI/apiKeyReuse.test.ts
index 3fe80d2a..920953f1 100644
--- a/src/components/common/Settings/AI/apiKeyReuse.test.ts
+++ b/src/components/common/Settings/AI/apiKeyReuse.test.ts
@@ -44,4 +44,52 @@ describe('canReuseExistingApiKey', () => {
 
     assert.equal(result, false)
   })
+
+  it('requires a new key when base URL changes in openai-compat mode', () => {
+    const result = canReuseExistingApiKey({
+      mode: 'edit',
+      existingApiKeySet: true,
+      hasNewApiKey: false,
+      originalProvider: 'openai-compatible',
+      currentProvider: 'openai-compatible',
+      originalConnectionMode: 'openai-compat',
+      currentConnectionMode: 'openai-compat',
+      originalBaseUrl: 'https://api.provider-a.com',
+      currentBaseUrl: 'https://api.provider-b.com',
+    })
+
+    assert.equal(result, false)
+  })
+
+  it('allows reusing key when base URL is unchanged in openai-compat mode (trailing slash normalized)', () => {
+    const result = canReuseExistingApiKey({
+      mode: 'edit',
+      existingApiKeySet: true,
+      hasNewApiKey: false,
+      originalProvider: 'openai-compatible',
+      currentProvider: 'openai-compatible',
+      originalConnectionMode: 'openai-compat',
+      currentConnectionMode: 'openai-compat',
+      originalBaseUrl: 'https://api.provider-a.com/',
+      currentBaseUrl: 'https://api.provider-a.com',
+    })
+
+    assert.equal(result, true)
+  })
+
+  it('allows reusing key when base URL is unchanged in openai-compat mode', () => {
+    const result = canReuseExistingApiKey({
+      mode: 'edit',
+      existingApiKeySet: true,
+      hasNewApiKey: false,
+      originalProvider: 'openai-compatible',
+      currentProvider: 'openai-compatible',
+      originalConnectionMode: 'openai-compat',
+      currentConnectionMode: 'openai-compat',
+      originalBaseUrl: 'https://api.provider-a.com',
+      currentBaseUrl: 'https://api.provider-a.com',
+    })
+
+    assert.equal(result, true)
+  })
 })
diff --git a/src/components/common/Settings/AI/apiKeyReuse.ts b/src/components/common/Settings/AI/apiKeyReuse.ts
index bb09b996..6ec3e4aa 100644
--- a/src/components/common/Settings/AI/apiKeyReuse.ts
+++ b/src/components/common/Settings/AI/apiKeyReuse.ts
@@ -8,6 +8,10 @@ export interface ApiKeyReuseInput {
   currentProvider: string
   originalConnectionMode?: ConnectionMode
   currentConnectionMode: ConnectionMode
+  /** Original base URL (for openai-compat mode endpoint change detection) */
+  originalBaseUrl?: string
+  /** Current base URL entered by the user */
+  currentBaseUrl?: string
 }
 
 export function getConnectionModeForConfig(config: {
@@ -23,11 +27,21 @@ export function getConnectionModeForConfig(config: {
 }
 
 export function canReuseExistingApiKey(input: ApiKeyReuseInput): boolean {
-  return (
+  const baseConditions =
     input.mode === 'edit' &&
     !!input.existingApiKeySet &&
     !input.hasNewApiKey &&
     input.originalProvider === input.currentProvider &&
     input.originalConnectionMode === input.currentConnectionMode
-  )
+
+  if (!baseConditions) return false
+
+  // For openai-compat mode, a base URL change means a different endpoint/service,
+  // so the existing credential must not be silently reused without re-validation.
+  if (input.currentConnectionMode === 'openai-compat') {
+    const normalizeUrl = (url?: string) => url?.trim().replace(/\/+$/, '') || ''
+    return normalizeUrl(input.originalBaseUrl) === normalizeUrl(input.currentBaseUrl)
+  }
+
+  return true
 }
diff --git a/src/components/common/Settings/AI/useAIConfigForm.ts b/src/components/common/Settings/AI/useAIConfigForm.ts
index d01e3c70..ed8c3897 100644
--- a/src/components/common/Settings/AI/useAIConfigForm.ts
+++ b/src/components/common/Settings/AI/useAIConfigForm.ts
@@ -174,6 +174,8 @@ export function useAIConfigForm(props: {
         currentProvider: provider,
         originalConnectionMode: props.config.value ? getConnectionModeForConfig(props.config.value) : undefined,
         currentConnectionMode: connectionMode.value,
+        originalBaseUrl: props.config.value?.baseUrl,
+        currentBaseUrl: baseUrl.trim() || undefined,
       })
 
     if (isLocalMode.value) {
@@ -709,6 +711,8 @@ export function useAIConfigForm(props: {
       currentProvider: formData.value.provider,
       originalConnectionMode: props.config.value ? getConnectionModeForConfig(props.config.value) : undefined,
       currentConnectionMode: connectionMode.value,
+      originalBaseUrl: props.config.value?.baseUrl,
+      currentBaseUrl: formData.value.baseUrl.trim() || undefined,
     })
     if (isEditWithExistingKey) {
       return doSave()