diff --git a/src/agents/model-forward-compat.ts b/src/agents/model-forward-compat.ts
index d19ab3d1a3f..e27260db832 100644
--- a/src/agents/model-forward-compat.ts
+++ b/src/agents/model-forward-compat.ts
@@ -241,15 +241,17 @@ function resolveAnthropicSonnet46ForwardCompatModel(
   });
 }
 
-// gemini-3.1-pro-preview / gemini-3.1-flash-preview are not present in pi-ai's built-in
-// google-gemini-cli catalog yet. Clone the nearest gemini-3 template so users don't get
-// "Unknown model" errors when Google Gemini CLI gains new minor-version models.
-function resolveGoogleGeminiCli31ForwardCompatModel(
+// gemini-3.1-pro-preview / gemini-3.1-flash-preview are not present in some pi-ai
+// Google catalogs yet. Clone the nearest gemini-3 template so users don't get
+// "Unknown model" errors when Google ships new minor-version models before pi-ai
+// updates its built-in registry.
+function resolveGoogle31ForwardCompatModel(
   provider: string,
   modelId: string,
   modelRegistry: ModelRegistry,
 ): Model<Api> | undefined {
-  if (normalizeProviderId(provider) !== "google-gemini-cli") {
+  const normalizedProvider = normalizeProviderId(provider);
+  if (normalizedProvider !== "google" && normalizedProvider !== "google-gemini-cli") {
     return undefined;
   }
   const trimmed = modelId.trim();
@@ -265,7 +267,7 @@ function resolveGoogleGeminiCli31ForwardCompatModel(
   }
 
   return cloneFirstTemplateModel({
-    normalizedProvider: "google-gemini-cli",
+    normalizedProvider,
     trimmedModelId: trimmed,
     templateIds: [...templateIds],
     modelRegistry,
@@ -326,6 +328,6 @@ export function resolveForwardCompatModel(
     resolveAnthropicOpus46ForwardCompatModel(provider, modelId, modelRegistry) ??
     resolveAnthropicSonnet46ForwardCompatModel(provider, modelId, modelRegistry) ??
     resolveZaiGlm5ForwardCompatModel(provider, modelId, modelRegistry) ??
-    resolveGoogleGeminiCli31ForwardCompatModel(provider, modelId, modelRegistry)
+    resolveGoogle31ForwardCompatModel(provider, modelId, modelRegistry)
   );
 }
diff --git a/src/agents/pi-embedded-runner/model.forward-compat.test.ts b/src/agents/pi-embedded-runner/model.forward-compat.test.ts
index 310f62d0d32..bdee17f1e9a 100644
--- a/src/agents/pi-embedded-runner/model.forward-compat.test.ts
+++ b/src/agents/pi-embedded-runner/model.forward-compat.test.ts
@@ -11,6 +11,7 @@ import {
   GOOGLE_GEMINI_CLI_FLASH_TEMPLATE_MODEL,
   GOOGLE_GEMINI_CLI_PRO_TEMPLATE_MODEL,
   makeModel,
+  mockDiscoveredModel,
   mockGoogleGeminiCliFlashTemplateModel,
   mockGoogleGeminiCliProTemplateModel,
   mockOpenAICodexTemplateModel,
@@ -102,6 +103,54 @@ describe("pi embedded model e2e smoke", () => {
     });
   });
 
+  it("builds a google forward-compat fallback for gemini-3.1-pro-preview", () => {
+    mockDiscoveredModel({
+      provider: "google",
+      modelId: "gemini-3-pro-preview",
+      templateModel: {
+        ...GOOGLE_GEMINI_CLI_PRO_TEMPLATE_MODEL,
+        provider: "google",
+        api: "google-generative-ai",
+        baseUrl: "https://generativelanguage.googleapis.com",
+      },
+    });
+
+    const result = resolveModel("google", "gemini-3.1-pro-preview", "/tmp/agent");
+    expect(result.error).toBeUndefined();
+    expect(result.model).toMatchObject({
+      provider: "google",
+      api: "google-generative-ai",
+      baseUrl: "https://generativelanguage.googleapis.com",
+      id: "gemini-3.1-pro-preview",
+      name: "gemini-3.1-pro-preview",
+      reasoning: true,
+    });
+  });
+
+  it("builds a google forward-compat fallback for gemini-3.1-flash-lite-preview", () => {
+    mockDiscoveredModel({
+      provider: "google",
+      modelId: "gemini-3-flash-preview",
+      templateModel: {
+        ...GOOGLE_GEMINI_CLI_FLASH_TEMPLATE_MODEL,
+        provider: "google",
+        api: "google-generative-ai",
+        baseUrl: "https://generativelanguage.googleapis.com",
+      },
+    });
+
+    const result = resolveModel("google", "gemini-3.1-flash-lite-preview", "/tmp/agent");
+    expect(result.error).toBeUndefined();
+    expect(result.model).toMatchObject({
+      provider: "google",
+      api: "google-generative-ai",
+      baseUrl: "https://generativelanguage.googleapis.com",
+      id: "gemini-3.1-flash-lite-preview",
+      name: "gemini-3.1-flash-lite-preview",
+      reasoning: true,
+    });
+  });
+
   it("keeps unknown-model errors for unrecognized google-gemini-cli model IDs", () => {
     const result = resolveModel("google-gemini-cli", "gemini-4-unknown", "/tmp/agent");
     expect(result.model).toBeUndefined();