cache: add grpc read-only response caching

apps/admin-api/src/app.rs

@@ -3605,6 +3605,7 @@ mod tests {
                 package: "echo".to_owned(),
                 service: "EchoService".to_owned(),
                 method: "UnaryEcho".to_owned(),
+                read_only: false,
                 descriptor_ref: DescriptorId::new("desc_echo"),
                 descriptor_set_b64: grpc_test_support::descriptor_set_b64(),
             }),
@@ -3658,6 +3659,7 @@ mod tests {
             package: "echo".to_owned(),
             service: "EchoService".to_owned(),
             method: "ServerEcho".to_owned(),
+            read_only: false,
             descriptor_ref: DescriptorId::new("desc_echo_stream"),
             descriptor_set_b64: grpc_test_support::descriptor_set_b64(),
         });

apps/admin-api/src/service.rs

@@ -5061,13 +5061,23 @@ fn validate_response_cache_policy(
         ));
     }
 
+    if execution_config.streaming.is_some() {
+        return Err(ApiError::validation_with_context(
+            "response cache is supported only for unary operations".to_owned(),
+            json!({
+                "field": "execution_config.response_cache",
+            }),
+        ));
+    }
+
     match target {
         Target::Rest(rest_target) if rest_target.method == crank_core::HttpMethod::Get => {}
         Target::Graphql(graphql_target)
             if graphql_target.operation_type == crank_core::GraphqlOperationType::Query => {}
+        Target::Grpc(grpc_target) if grpc_target.read_only => {}
         _ => {
             return Err(ApiError::validation_with_context(
-                "response cache is supported only for REST GET and GraphQL query operations"
+                "response cache is supported only for REST GET, GraphQL query, and read-only unary gRPC operations"
                     .to_owned(),
                 json!({
                     "field": "execution_config.response_cache",
@@ -5093,8 +5103,8 @@ mod tests {
     use std::collections::BTreeMap;
 
     use crank_core::{
-        ExecutionConfig, GraphqlOperationType, GraphqlTarget, HttpMethod, ResponseCachePolicy,
-        RestTarget, Target,
+        ExecutionConfig, GraphqlOperationType, GraphqlTarget, GrpcTarget, HttpMethod,
+        ResponseCachePolicy, RestTarget, StreamingConfig, Target, TransportBehavior,
     };
 
     use super::validate_response_cache_policy;
@@ -5145,7 +5155,7 @@ mod tests {
         assert!(matches!(error, crate::error::ApiError::Validation { .. }));
         assert_eq!(
             error.to_string(),
-            "response cache is supported only for REST GET and GraphQL query operations"
+            "response cache is supported only for REST GET, GraphQL query, and read-only unary gRPC operations"
         );
     }
 
@@ -5162,6 +5172,90 @@ mod tests {
 
         assert!(result.is_ok());
     }
+
+    #[test]
+    fn accepts_response_cache_for_read_only_unary_grpc() {
+        let target = Target::Grpc(GrpcTarget {
+            server_addr: "http://127.0.0.1:50051".to_owned(),
+            package: "echo".to_owned(),
+            service: "EchoService".to_owned(),
+            method: "UnaryEcho".to_owned(),
+            read_only: true,
+            descriptor_ref: "desc_echo".into(),
+            descriptor_set_b64: "ZmFrZQ==".to_owned(),
+        });
+
+        let result = validate_response_cache_policy(&target, &cacheable_execution_config());
+
+        assert!(result.is_ok());
+    }
+
+    #[test]
+    fn rejects_response_cache_for_non_read_only_grpc() {
+        let target = Target::Grpc(GrpcTarget {
+            server_addr: "http://127.0.0.1:50051".to_owned(),
+            package: "echo".to_owned(),
+            service: "EchoService".to_owned(),
+            method: "UnaryEcho".to_owned(),
+            read_only: false,
+            descriptor_ref: "desc_echo".into(),
+            descriptor_set_b64: "ZmFrZQ==".to_owned(),
+        });
+
+        let error =
+            validate_response_cache_policy(&target, &cacheable_execution_config()).unwrap_err();
+
+        assert!(matches!(error, crate::error::ApiError::Validation { .. }));
+        assert_eq!(
+            error.to_string(),
+            "response cache is supported only for REST GET, GraphQL query, and read-only unary gRPC operations"
+        );
+    }
+
+    #[test]
+    fn rejects_response_cache_for_streaming_grpc() {
+        let target = Target::Grpc(GrpcTarget {
+            server_addr: "http://127.0.0.1:50051".to_owned(),
+            package: "echo".to_owned(),
+            service: "EchoService".to_owned(),
+            method: "ServerEcho".to_owned(),
+            read_only: true,
+            descriptor_ref: "desc_echo".into(),
+            descriptor_set_b64: "ZmFrZQ==".to_owned(),
+        });
+        let mut execution_config = cacheable_execution_config();
+        execution_config.streaming = Some(StreamingConfig {
+            mode: crank_core::ExecutionMode::Window,
+            transport_behavior: TransportBehavior::ServerStream,
+            window_duration_ms: Some(1_000),
+            poll_interval_ms: None,
+            upstream_timeout_ms: Some(1_000),
+            idle_timeout_ms: None,
+            max_session_lifetime_ms: None,
+            max_items: Some(1),
+            max_bytes: None,
+            aggregation_mode: crank_core::AggregationMode::RawItems,
+            summary_path: None,
+            items_path: None,
+            cursor_path: None,
+            status_path: None,
+            done_path: None,
+            redacted_paths: Vec::new(),
+            truncate_item_fields: false,
+            max_field_length: None,
+            drop_duplicates: false,
+            sampling_rate: None,
+            tool_family: crank_core::ToolFamilyConfig::default(),
+        });
+
+        let error = validate_response_cache_policy(&target, &execution_config).unwrap_err();
+
+        assert!(matches!(error, crate::error::ApiError::Validation { .. }));
+        assert_eq!(
+            error.to_string(),
+            "response cache is supported only for unary operations"
+        );
+    }
 }
 
 fn enrich_operation_summary(