google_ai: Add Gemini 3.7 Flash (#62670)

Follow-up to #62010, which added Gemini 3.6 Flash.

Google released Gemini 3.7 Flash on August 13, 2026. It keeps the 1
million token context window and the 64k output limit, and supports
thinking.

Unlike 3.5 and 3.6 Flash, it does not accept `thinking_level: MINIMAL`
(the API returns a validation error). So it exposes Low, Medium and
High, defaulting to Medium, and `disabled_thinking_level` in
`completion.rs` returns Low for it instead of Minimal when the user
turns thinking off.

The provider builds its model list from `google_ai::Model::iter()`, so
adding the enum variant is enough for it to show up in the model
dropdown.

Release Notes:

- Added Gemini 3.7 Flash to the Google AI models

crates/google_ai/src/completion.rs

@@ -249,7 +249,12 @@ fn is_google_thinking_model(model_id: &str) -> bool {
 
 fn disabled_thinking_level(model_id: &str) -> Option<ThinkingLevel> {
     match model_id {
-        model_id if model_id.starts_with("gemini-3") && model_id.contains("-pro") => {
+        // `gemini-3.7-flash` rejects `MINIMAL` with a validation error, so `LOW` is
+        // the lowest level available to it.
+        model_id
+            if model_id.starts_with("gemini-3.7-flash")
+                || (model_id.starts_with("gemini-3") && model_id.contains("-pro")) =>
+        {
             Some(ThinkingLevel::Low)
         }
         model_id if model_id.starts_with("gemini-3") => Some(ThinkingLevel::Minimal),
@@ -704,6 +709,23 @@ mod tests {
         assert_eq!(mapper.stop_reason, StopReason::Refusal);
     }
 
+    #[test]
+    fn test_disabled_thinking_level_per_model() {
+        assert_eq!(
+            disabled_thinking_level("gemini-3.7-flash"),
+            Some(ThinkingLevel::Low)
+        );
+        assert_eq!(
+            disabled_thinking_level("gemini-3.1-pro-preview"),
+            Some(ThinkingLevel::Low)
+        );
+        assert_eq!(
+            disabled_thinking_level("gemini-3.6-flash"),
+            Some(ThinkingLevel::Minimal)
+        );
+        assert_eq!(disabled_thinking_level("gemini-2.5-flash"), None);
+    }
+
     #[test]
     fn test_function_call_with_signature_creates_tool_use_with_signature() {
         let mut mapper = GoogleEventMapper::new();

crates/google_ai/src/google_ai.rs

@@ -533,6 +533,8 @@ pub enum Model {
     Gemini35Flash,
     #[serde(rename = "gemini-3.6-flash")]
     Gemini36Flash,
+    #[serde(rename = "gemini-3.7-flash")]
+    Gemini37Flash,
     #[serde(rename = "gemini-3.1-pro-preview", alias = "gemini-3-pro-preview")]
     Gemini31Pro,
     #[serde(rename = "custom")]
@@ -560,6 +562,7 @@ impl Model {
             Self::Gemini3Flash => "gemini-3-flash-preview",
             Self::Gemini35Flash => "gemini-3.5-flash",
             Self::Gemini36Flash => "gemini-3.6-flash",
+            Self::Gemini37Flash => "gemini-3.7-flash",
             Self::Gemini31Pro => "gemini-3.1-pro-preview",
             Self::Custom { name, .. } => name,
         }
@@ -573,6 +576,7 @@ impl Model {
             Self::Gemini3Flash => "gemini-3-flash-preview",
             Self::Gemini35Flash => "gemini-3.5-flash",
             Self::Gemini36Flash => "gemini-3.6-flash",
+            Self::Gemini37Flash => "gemini-3.7-flash",
             Self::Gemini31Pro => "gemini-3.1-pro-preview",
             Self::Custom { name, .. } => name,
         }
@@ -587,6 +591,7 @@ impl Model {
             Self::Gemini3Flash => "Gemini 3 Flash",
             Self::Gemini35Flash => "Gemini 3.5 Flash",
             Self::Gemini36Flash => "Gemini 3.6 Flash",
+            Self::Gemini37Flash => "Gemini 3.7 Flash",
             Self::Gemini31Pro => "Gemini 3.1 Pro",
             Self::Custom {
                 name, display_name, ..
@@ -603,6 +608,7 @@ impl Model {
             | Self::Gemini3Flash
             | Self::Gemini35Flash
             | Self::Gemini36Flash
+            | Self::Gemini37Flash
             | Self::Gemini31Pro => 1_048_576,
             Self::Custom { max_tokens, .. } => *max_tokens,
         }
@@ -617,6 +623,7 @@ impl Model {
             | Model::Gemini3Flash
             | Model::Gemini35Flash
             | Model::Gemini36Flash
+            | Model::Gemini37Flash
             | Model::Gemini31Pro => Some(65_536),
             Model::Custom { .. } => None,
         }
@@ -640,6 +647,7 @@ impl Model {
                 | Self::Gemini3Flash
                 | Self::Gemini35Flash
                 | Self::Gemini36Flash
+                | Self::Gemini37Flash
                 | Self::Gemini31Pro
                 | Self::Custom {
                     mode: GoogleModelMode::Thinking { .. },
@@ -659,7 +667,7 @@ impl Model {
                 ThinkingLevel::Medium,
                 ThinkingLevel::High,
             ],
-            Self::Gemini31Pro => &[
+            Self::Gemini37Flash | Self::Gemini31Pro => &[
                 ThinkingLevel::Low,
                 ThinkingLevel::Medium,
                 ThinkingLevel::High,
@@ -674,6 +682,7 @@ impl Model {
             Self::Gemini3Flash => Some(ThinkingLevel::High),
             Self::Gemini35Flash => Some(ThinkingLevel::Medium),
             Self::Gemini36Flash => Some(ThinkingLevel::Medium),
+            Self::Gemini37Flash => Some(ThinkingLevel::Medium),
             Self::Gemini31Pro => Some(ThinkingLevel::High),
             _ => None,
         }
@@ -692,6 +701,7 @@ impl Model {
             | Self::Gemini3Flash
             | Self::Gemini35Flash
             | Self::Gemini36Flash
+            | Self::Gemini37Flash
             | Self::Gemini31Pro => GoogleModelMode::Thinking {
                 budget_tokens: None,
             },
@@ -724,6 +734,27 @@ mod tests {
         assert_eq!(deserialized, Model::Gemini36Flash);
     }
 
+    #[test]
+    fn test_gemini_3_7_flash_model_metadata() {
+        let model = Model::Gemini37Flash;
+        assert_eq!(model.id(), "gemini-3.7-flash");
+        assert_eq!(model.request_id(), "gemini-3.7-flash");
+        assert_eq!(model.display_name(), "Gemini 3.7 Flash");
+        assert_eq!(
+            model.supported_thinking_levels(),
+            &[
+                ThinkingLevel::Low,
+                ThinkingLevel::Medium,
+                ThinkingLevel::High
+            ]
+        );
+
+        let serialized = serde_json::to_value(&model).unwrap();
+        assert_eq!(serialized, json!("gemini-3.7-flash"));
+        let deserialized: Model = serde_json::from_value(json!("gemini-3.7-flash")).unwrap();
+        assert_eq!(deserialized, Model::Gemini37Flash);
+    }
+
     #[test]
     fn test_function_call_part_with_signature_serializes_correctly() {
         let part = FunctionCallPart {