diff --git a/src/web-server/model-pricing.ts b/src/web-server/model-pricing.ts
index 9cf381e7..d8e40679 100644
--- a/src/web-server/model-pricing.ts
+++ b/src/web-server/model-pricing.ts
@@ -718,10 +718,16 @@ const MODEL_PRICING_ALIASES: Record<string, string> = {
   'qwen3-235b': 'qwen3-max',
   'qwen3-vl-plus': 'qwen3.5-plus',
   'qwen3-32b': 'qwen3.5-plus',
+  'gemini-3-flash-preview': 'gemini-2.5-flash',
+  'gemini-3-flash-preview-customtools': 'gemini-2.5-flash',
   'gemini-3.1-pro-preview': 'gemini-3-pro-preview',
+  'gemini-3.1-flash-preview': 'gemini-2.5-flash',
   'gemini-3.1-pro-preview-customtools': 'gemini-3-pro-preview',
+  'gemini-3.1-flash-preview-customtools': 'gemini-2.5-flash',
   'gemini-3-1-pro-preview': 'gemini-3-pro-preview',
+  'gemini-3-1-flash-preview': 'gemini-2.5-flash',
   'gemini-3-1-pro-preview-customtools': 'gemini-3-pro-preview',
+  'gemini-3-1-flash-preview-customtools': 'gemini-2.5-flash',
 };
 
 // Default pricing for unknown models
diff --git a/tests/unit/cliproxy/model-catalog.test.js b/tests/unit/cliproxy/model-catalog.test.js
index e394ed1a..4d675641 100644
--- a/tests/unit/cliproxy/model-catalog.test.js
+++ b/tests/unit/cliproxy/model-catalog.test.js
@@ -261,6 +261,21 @@ describe('Model Catalog', () => {
       );
     });
 
+    it('falls back to the next supported model when the default is excluded', () => {
+      const { getSuggestedReplacementModel } = modelCatalog;
+
+      expect(getSuggestedReplacementModel('agy', 'claude-opus-4-6-thinking')).toBe(
+        'claude-sonnet-4-6'
+      );
+      expect(getSuggestedReplacementModel('agy')).toBe('claude-opus-4-6-thinking');
+    });
+
+    it('returns undefined when no provider catalog exists', () => {
+      const { getSuggestedReplacementModel } = modelCatalog;
+
+      expect(getSuggestedReplacementModel('qwen')).toBeUndefined();
+    });
+
     it('returns undefined for unknown model', () => {
       const { findModel } = modelCatalog;
       const model = findModel('agy', 'unknown-model');
diff --git a/tests/unit/model-pricing.test.ts b/tests/unit/model-pricing.test.ts
index 3b483563..470ced04 100644
--- a/tests/unit/model-pricing.test.ts
+++ b/tests/unit/model-pricing.test.ts
@@ -76,6 +76,22 @@ describe('model-pricing', () => {
       expect(pricing).not.toEqual(getModelPricing('unknown-model-xyz'));
     });
 
+    it('should map Gemini 3 and 3.1 Flash preview variants to flash pricing', () => {
+      const canonical = getModelPricing('gemini-2.5-flash');
+      const aliases = [
+        'gemini-3-flash-preview',
+        'gemini-3-flash-preview-customtools',
+        'gemini-3.1-flash-preview',
+        'gemini-3.1-flash-preview-customtools',
+        'gemini-3-1-flash-preview',
+        'gemini-3-1-flash-preview-customtools',
+      ];
+
+      for (const model of aliases) {
+        expect(getModelPricing(model)).toEqual(canonical);
+      }
+    });
+
     it('should return different pricing for different model tiers', () => {
       const sonnet = getModelPricing('claude-sonnet-4-5');
       const opus = getModelPricing('claude-opus-4-5-20251101');
diff --git a/ui/src/lib/model-catalogs.ts b/ui/src/lib/model-catalogs.ts
index 4ce9a65d..27b78d27 100644
--- a/ui/src/lib/model-catalogs.ts
+++ b/ui/src/lib/model-catalogs.ts
@@ -5,7 +5,7 @@
 
 import type { ModelEntry, ProviderCatalog } from '@/components/cliproxy/provider-model-selector';
 import { stripModelConfigurationSuffixes } from '@/lib/extended-context-utils';
-import { GEMINI_MINOR_VERSION_COMPATIBILITY_IDS } from '../../../src/shared/gemini-minor-version-compatibility';
+import { GEMINI_MINOR_VERSION_COMPATIBILITY_IDS } from '@shared/gemini-minor-version-compatibility';
 
 const GEMINI_PREVIEW_MODEL_ID_PATTERN =
   /^gemini-(\d+(?:[.-]\d+)*)-(pro|flash)-preview(-customtools)?$/i;
diff --git a/ui/tests/unit/ui/lib/preset-utils.test.ts b/ui/tests/unit/ui/lib/preset-utils.test.ts
index b219f9c6..e4d0c618 100644
--- a/ui/tests/unit/ui/lib/preset-utils.test.ts
+++ b/ui/tests/unit/ui/lib/preset-utils.test.ts
@@ -92,4 +92,17 @@ describe('claude preset utils', () => {
       'gemini-3-flash-preview'
     );
   });
+
+  it('passes through non-Gemini model ids unchanged', () => {
+    expect(resolveCatalogModelId('claude-sonnet-4-6')).toBe('claude-sonnet-4-6');
+  });
+
+  it('falls back to the catalog id when no live model matches', () => {
+    expect(resolveCatalogModelId('gemini-3.1-pro-preview', [])).toBe('gemini-3.1-pro-preview');
+    expect(
+      resolveCatalogModelId('gemini-3.1-pro-preview', [
+        { id: 'gemini-2.5-pro', owned_by: 'google' },
+      ])
+    ).toBe('gemini-3.1-pro-preview');
+  });
 });
diff --git a/ui/tsconfig.app.json b/ui/tsconfig.app.json
index 99fbd39c..a751b0ca 100644
--- a/ui/tsconfig.app.json
+++ b/ui/tsconfig.app.json
@@ -26,7 +26,8 @@
     /* Path alias */
     "baseUrl": ".",
     "paths": {
-      "@/*": ["./src/*"]
+      "@/*": ["./src/*"],
+      "@shared/*": ["../src/shared/*"]
     }
   },
   "include": ["src"]
diff --git a/ui/vite.config.ts b/ui/vite.config.ts
index 39c8d654..4a31e9f5 100644
--- a/ui/vite.config.ts
+++ b/ui/vite.config.ts
@@ -11,6 +11,7 @@ export default defineConfig({
   plugins: [react(), tailwindcss()],
   resolve: {
     alias: {
+      '@shared': path.resolve(REPO_ROOT, './src/shared'),
       '@': path.resolve(__dirname, './src'),
     },
   },
diff --git a/ui/vitest.config.ts b/ui/vitest.config.ts
index a0501bb5..0b3f2697 100644
--- a/ui/vitest.config.ts
+++ b/ui/vitest.config.ts
@@ -45,6 +45,7 @@ export default defineConfig({
   },
   resolve: {
     alias: {
+      '@shared': path.resolve(__dirname, '../src/shared'),
       '@': path.resolve(__dirname, './src'),
       '@tests': path.resolve(__dirname, './tests'),
     },