feat(ai): support 1M context window for Anthropic resources (#7891)

* feat(ai): support 1M context window for Anthropic resources

Add `enable_1m_context` boolean field to Anthropic resource configuration.
When enabled (and not using Vertex AI), sends the `anthropic-beta: context-1m-2025-08-07`
header in both the API proxy layer and the AI agent worker layer.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* fix(ai): add serde alias for enable_1M_context DB field name

The resource_type schema uses `enable_1M_context` (uppercase M) but
serde only matched `enable_1m_context` and `enable1mContext`, causing
the field to always deserialize as false.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

backend/windmill-api/src/ai.rs

@@ -169,6 +169,9 @@ struct AIStandardResource {
     /// Platform for Anthropic API (standard or google_vertex_ai)
     #[serde(default)]
     platform: AnthropicPlatform,
+    /// Enable 1M context window for Anthropic
+    #[serde(alias = "enable_1M_context", default)]
+    enable_1m_context: bool,
 }
 
 #[derive(Deserialize, Debug)]
@@ -197,6 +200,7 @@ struct AIRequestConfig {
     #[allow(dead_code)]
     pub aws_secret_access_key: Option<String>,
     pub platform: AnthropicPlatform,
+    pub enable_1m_context: bool,
 }
 
 impl AIRequestConfig {
@@ -216,10 +220,12 @@ impl AIRequestConfig {
             aws_access_key_id,
             aws_secret_access_key,
             platform,
+            enable_1m_context,
         ) = match resource {
             AIResource::Standard(resource) => {
                 let region = resource.region.clone();
                 let platform = resource.platform.clone();
+                let enable_1m_context = resource.enable_1m_context;
                 // Skip get_base_url for Bedrock - it uses SDK directly, not HTTP
                 let base_url = if matches!(provider, AIProvider::AWSBedrock) {
                     String::new()
@@ -258,6 +264,7 @@ impl AIRequestConfig {
                     aws_access_key_id,
                     aws_secret_access_key,
                     platform,
+                    enable_1m_context,
                 )
             }
             AIResource::OAuth(resource) => {
@@ -279,6 +286,7 @@ impl AIRequestConfig {
                     None,
                     None,
                     AnthropicPlatform::Standard,
+                    false,
                 )
             }
         };
@@ -293,6 +301,7 @@ impl AIRequestConfig {
             aws_access_key_id,
             aws_secret_access_key,
             platform,
+            enable_1m_context,
         })
     }
 
@@ -394,6 +403,10 @@ impl AIRequestConfig {
             }
         }
 
+        if is_anthropic_sdk && self.enable_1m_context {
+            request = request.header("anthropic-beta", "context-1m-2025-08-07");
+        }
+
         // Add authentication headers
         if let Some(api_key) = self.api_key {
             if is_azure {

backend/windmill-worker/src/ai/providers/anthropic.rs

@@ -354,11 +354,16 @@ pub struct AnthropicQueryBuilder {
     #[allow(dead_code)]
     provider_kind: AIProvider,
     platform: AnthropicPlatform,
+    enable_1m_context: bool,
 }
 
 impl AnthropicQueryBuilder {
-    pub fn new(provider_kind: AIProvider, platform: AnthropicPlatform) -> Self {
-        Self { provider_kind, platform }
+    pub fn new(
+        provider_kind: AIProvider,
+        platform: AnthropicPlatform,
+        enable_1m_context: bool,
+    ) -> Self {
+        Self { provider_kind, platform, enable_1m_context }
     }
 
     fn is_vertex(&self) -> bool {
@@ -582,10 +587,14 @@ impl QueryBuilder for AnthropicQueryBuilder {
             vec![("Authorization", format!("Bearer {}", api_key))]
         } else {
             // Standard Anthropic API uses x-api-key and anthropic-version header
-            vec![
+            let mut headers = vec![
                 ("x-api-key", api_key.to_string()),
                 ("anthropic-version", ANTHROPIC_VERSION_STANDARD.to_string()),
-            ]
+            ];
+            if self.enable_1m_context {
+                headers.push(("anthropic-beta", "context-1m-2025-08-07".to_string()));
+            }
+            headers
         }
     }
 }

backend/windmill-worker/src/ai/query_builder.rs

@@ -119,6 +119,7 @@ pub fn create_query_builder(provider: &ProviderWithResource) -> Box<dyn QueryBui
         AIProvider::Anthropic => Box::new(AnthropicQueryBuilder::new(
             provider.kind.clone(),
             provider.get_platform().clone(),
+            provider.get_enable_1m_context(),
         )),
         AIProvider::OpenRouter => Box::new(OpenRouterQueryBuilder::new()),
         // All other providers use the completion endpoint

backend/windmill-worker/src/ai/types.rs

@@ -190,6 +190,9 @@ pub struct ProviderResource {
     /// Platform for Anthropic API (standard or google_vertex_ai)
     #[serde(default)]
     pub platform: AnthropicPlatform,
+    /// Enable 1M context window for Anthropic
+    #[serde(alias = "enable_1M_context", default)]
+    pub enable_1m_context: bool,
 }
 
 #[derive(Deserialize, Debug)]
@@ -232,6 +235,10 @@ impl ProviderWithResource {
     pub fn get_platform(&self) -> &AnthropicPlatform {
         &self.resource.platform
     }
+
+    pub fn get_enable_1m_context(&self) -> bool {
+        self.resource.enable_1m_context
+    }
 }
 
 /// Token usage information from the AI provider