diff --git a/CLAUDE.md b/CLAUDE.md
index 7f51271..d35c3fd 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -197,3 +197,4 @@ Core clients are tested using mocked API calls with wiremock. All functions maki
 
 ### Comments
 - When doing anything out of the ordinary or breaking conventions or patterns, add a comment explaining the "why" behind it
+- Do not reference Linear issue IDs (e.g. `DX-1234`), PR numbers, ticket URLs, or other internal tracking identifiers in code comments. The "why" should be self-contained — describe the constraint or behaviour itself, not where to look it up. Internal context belongs in the commit message or PR description.
diff --git a/crates/core/README.md b/crates/core/README.md
index 7983c37..3a2bdb0 100644
--- a/crates/core/README.md
+++ b/crates/core/README.md
@@ -836,7 +836,7 @@ Returns metric series for an endpoint over a time period.
 
 **Parameters**: `id` (endpoint id, required); body: `period` (`"hour"` | `"day"` | `"week"` | `"month"`), `metric` (e.g. `"method_calls_over_time"`, `"response_status_breakdown"`).
 
-**Returns**: `GetEndpointMetricsResponse` with `data: EndpointMetric[]`.
+**Returns**: `GetEndpointMetricsResponse` with `data: Vec<EndpointMetric>`. Each `EndpointMetric` has `tag: Vec<String>` and `data: Vec<Vec<i64>>` of `[timestamp, value]` pairs. Single-axis series (e.g. `response_time_over_time` with a percentile) come back as a one-element tag like `vec!["p95"]`; multi-axis series come back as `vec!["network", "arbitrum-mainnet"]`.
 
 ```rust
 // Rust
@@ -853,7 +853,7 @@ Returns account-level metric series. Supports an optional `percentile` (e.g. `"p
 
 **Parameters**: `period` (required), `metric` (required), `percentile` (string, optional).
 
-**Returns**: `GetAccountMetricsResponse` with `data: EndpointMetric[]`.
+**Returns**: `GetAccountMetricsResponse` with `data: Vec<EndpointMetric>`. See `get_endpoint_metrics` above for the `tag: Vec<String>` shape.
 
 ```rust
 // Rust
diff --git a/crates/core/examples/admin_e2e.rs b/crates/core/examples/admin_e2e.rs
index 542c2ac..e78496d 100644
--- a/crates/core/examples/admin_e2e.rs
+++ b/crates/core/examples/admin_e2e.rs
@@ -97,7 +97,17 @@ async fn main() {
         })
         .await
     {
-        Ok(resp) => println!("get_account_metrics: {} series", resp.data.len()),
+        Ok(resp) => {
+            let first = resp
+                .data
+                .first()
+                .map(|m| m.tag.join(":"))
+                .unwrap_or_else(|| "<none>".to_string());
+            println!(
+                "get_account_metrics: {} series, first tag: {first}",
+                resp.data.len()
+            );
+        }
         Err(e) => eprintln!("get_account_metrics error: {e}"),
     }
 
@@ -254,7 +264,17 @@ async fn main() {
         )
         .await
     {
-        Ok(resp) => println!("get_endpoint_metrics: {} series", resp.data.len()),
+        Ok(resp) => {
+            let first = resp
+                .data
+                .first()
+                .map(|m| m.tag.join(":"))
+                .unwrap_or_else(|| "<none>".to_string());
+            println!(
+                "get_endpoint_metrics: {} series, first tag: {first}",
+                resp.data.len()
+            );
+        }
         Err(e) => eprintln!("get_endpoint_metrics error: {e}"),
     }
 
diff --git a/crates/core/examples/streams_e2e.rs b/crates/core/examples/streams_e2e.rs
index cc1ac40..b8f0272 100644
--- a/crates/core/examples/streams_e2e.rs
+++ b/crates/core/examples/streams_e2e.rs
@@ -33,7 +33,7 @@ async fn main() {
         network: "ethereum-mainnet".to_string(),
         dataset: StreamDataset::Block,
         block: "17811625".to_string(),
-        filter_function: Some("ZnVuY3Rpb24gbWFpbihkYXRhKSB7IHJldHVybiBkYXRhOyB9".to_string()),
+        filter_function: "ZnVuY3Rpb24gbWFpbihkYXRhKSB7IHJldHVybiBkYXRhOyB9".to_string(),
         filter_language: None,
         address_book_config: None,
     };
diff --git a/crates/core/src/admin/endpoint_metrics.rs b/crates/core/src/admin/endpoint_metrics.rs
index 74979b0..d69bdfc 100644
--- a/crates/core/src/admin/endpoint_metrics.rs
+++ b/crates/core/src/admin/endpoint_metrics.rs
@@ -4,7 +4,34 @@ use napi_derive::napi;
 use pyo3::pyclass;
 #[cfg(feature = "python")]
 use pyo3_stub_gen::derive::gen_stub_pyclass;
-use serde::{Deserialize, Serialize};
+use serde::{Deserialize, Deserializer, Serialize};
+
+// The metrics endpoints return `tag` as either a plain string (single-axis
+// series like `"total"` or `"p95"`) or a tuple like `["network", "mainnet"]`
+// (multi-axis series). Normalise both to a `Vec<String>` so callers always
+// see an array.
+fn tag_as_vec<'de, D>(deserializer: D) -> Result<Vec<String>, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    use serde::de::Error;
+    match serde_json::Value::deserialize(deserializer)? {
+        serde_json::Value::String(s) => Ok(vec![s]),
+        serde_json::Value::Array(items) => items
+            .into_iter()
+            .map(|v| match v {
+                serde_json::Value::String(s) => Ok(s),
+                other => Err(D::Error::custom(format!(
+                    "expected string in tag array, got {other}"
+                ))),
+            })
+            .collect(),
+        serde_json::Value::Null => Ok(Vec::new()),
+        other => Err(D::Error::custom(format!(
+            "expected string or array of strings for tag, got {other}"
+        ))),
+    }
+}
 
 /// Parameters for `get_endpoint_metrics`.
 #[cfg_attr(feature = "python", gen_stub_pyclass)]
@@ -41,8 +68,11 @@ pub struct GetAccountMetricsRequest {
 pub struct EndpointMetric {
     /// Data points, each as `[timestamp, value]`.
     pub data: Vec<Vec<i64>>,
-    /// Human-readable tag identifying the series.
-    pub tag: String,
+    /// Tag identifying the series. Single-axis metrics return a one-element
+    /// vector (e.g. `["total"]`, `["p95"]`); multi-axis metrics return the
+    /// key/value pair (e.g. `["network", "arbitrum-mainnet"]`).
+    #[serde(deserialize_with = "tag_as_vec")]
+    pub tag: Vec<String>,
 }
 
 /// Response from `get_endpoint_metrics`.
@@ -70,3 +100,49 @@ pub struct GetAccountMetricsResponse {
     /// Error message when the request did not succeed.
     pub error: Option<String>,
 }
+
+#[cfg(test)]
+#[allow(clippy::unwrap_used, clippy::expect_used, clippy::panic)]
+mod tests {
+    use super::EndpointMetric;
+
+    #[test]
+    fn tag_deserializes_from_string() {
+        let m: EndpointMetric =
+            serde_json::from_str(r#"{"data": [[1, 2]], "tag": "total"}"#).unwrap();
+        assert_eq!(m.tag, vec!["total".to_string()]);
+    }
+
+    #[test]
+    fn tag_deserializes_from_tuple() {
+        let m: EndpointMetric =
+            serde_json::from_str(r#"{"data": [[1, 2]], "tag": ["network", "arbitrum-mainnet"]}"#)
+                .unwrap();
+        assert_eq!(
+            m.tag,
+            vec!["network".to_string(), "arbitrum-mainnet".to_string()]
+        );
+    }
+
+    #[test]
+    fn tag_deserializes_from_null() {
+        let m: EndpointMetric = serde_json::from_str(r#"{"data": [[1, 2]], "tag": null}"#).unwrap();
+        assert!(m.tag.is_empty());
+    }
+
+    #[test]
+    fn tag_rejects_mixed_array() {
+        let err =
+            serde_json::from_str::<EndpointMetric>(r#"{"data": [], "tag": ["x", 5]}"#).unwrap_err();
+        assert!(err.to_string().contains("expected string in tag array"));
+    }
+
+    #[test]
+    fn tag_rejects_object() {
+        let err = serde_json::from_str::<EndpointMetric>(r#"{"data": [], "tag": {"k": "v"}}"#)
+            .unwrap_err();
+        assert!(err
+            .to_string()
+            .contains("expected string or array of strings for tag"));
+    }
+}
diff --git a/crates/core/src/admin/mod.rs b/crates/core/src/admin/mod.rs
index 31b9927..42ec3b2 100644
--- a/crates/core/src/admin/mod.rs
+++ b/crates/core/src/admin/mod.rs
@@ -2638,7 +2638,7 @@ mod tests {
         Mock::given(method("GET"))
             .and(path("/endpoints/ep123/metrics"))
             .respond_with(ResponseTemplate::new(200).set_body_json(serde_json::json!({
-                "data": [{"data": [[1700000000, 42]], "tag": "mainnet"}],
+                "data": [{"data": [[1700000000, 42]], "tag": ["network", "mainnet"]}],
                 "error": null
             })))
             .mount(&server)
@@ -2655,7 +2655,10 @@ mod tests {
             .await
             .unwrap();
         assert_eq!(resp.data.len(), 1);
-        assert_eq!(resp.data[0].tag, "mainnet");
+        assert_eq!(
+            resp.data[0].tag,
+            vec!["network".to_string(), "mainnet".to_string()]
+        );
     }
 
     #[tokio::test]
@@ -2679,6 +2682,47 @@ mod tests {
         };
         let resp = sdk.admin.get_account_metrics(&params).await.unwrap();
         assert_eq!(resp.data.len(), 1);
+        assert_eq!(resp.data[0].tag, vec!["total".to_string()]);
+    }
+
+    // Regression: the metrics endpoints return `tag` as either a plain string
+    // (single-axis series) or a `[key, value]` tuple (multi-axis series).
+    // Exercise both shapes so any future serde change that breaks either
+    // branch fails loudly.
+    #[tokio::test]
+    async fn get_account_metrics_decodes_tuple_tag() {
+        let server = MockServer::start().await;
+
+        Mock::given(method("GET"))
+            .and(path("/metrics"))
+            .respond_with(ResponseTemplate::new(200).set_body_json(serde_json::json!({
+                "data": [
+                    {"tag": ["network", "arbitrum-mainnet"], "data": [[1779109200, 40]]},
+                    {"tag": ["network", "mainnet"], "data": [[1779116400, 40]]},
+                    {"tag": "p95", "data": [[1779116400, 12]]}
+                ],
+                "error": null
+            })))
+            .mount(&server)
+            .await;
+
+        let sdk = make_sdk(format!("{}/", server.uri()));
+        let params = GetAccountMetricsRequest {
+            period: "day".to_string(),
+            metric: "credits_over_time".to_string(),
+            percentile: None,
+        };
+        let resp = sdk.admin.get_account_metrics(&params).await.unwrap();
+        assert_eq!(resp.data.len(), 3);
+        assert_eq!(
+            resp.data[0].tag,
+            vec!["network".to_string(), "arbitrum-mainnet".to_string()]
+        );
+        assert_eq!(
+            resp.data[1].tag,
+            vec!["network".to_string(), "mainnet".to_string()]
+        );
+        assert_eq!(resp.data[2].tag, vec!["p95".to_string()]);
     }
 
     #[tokio::test]
@@ -2932,6 +2976,29 @@ mod tests {
         assert!(resp.data.unwrap().success.unwrap());
     }
 
+    // Wire-inspection regression: confirm an empty endpoint_ids array reaches
+    // the wire as `[]` (not omitted), so any future `skip_serializing_if`
+    // change that drops the empty case fails loudly.
+    #[tokio::test]
+    async fn update_team_endpoints_empty_array_wire_body() {
+        use wiremock::matchers::body_json;
+        let server = MockServer::start().await;
+        Mock::given(method("PATCH"))
+            .and(path("/teams/1/endpoints"))
+            .and(body_json(serde_json::json!({ "endpoint_ids": [] })))
+            .respond_with(ResponseTemplate::new(200).set_body_json(serde_json::json!({
+                "data": {"success": true},
+                "error": null
+            })))
+            .mount(&server)
+            .await;
+        let sdk = make_sdk(format!("{}/", server.uri()));
+        let params = UpdateTeamEndpointsRequest {
+            endpoint_ids: vec![],
+        };
+        sdk.admin.update_team_endpoints(1, &params).await.unwrap();
+    }
+
     #[tokio::test]
     async fn invite_team_member_success() {
         let server = MockServer::start().await;
diff --git a/crates/core/src/kvstore/mod.rs b/crates/core/src/kvstore/mod.rs
index 965bdbc..94172b9 100644
--- a/crates/core/src/kvstore/mod.rs
+++ b/crates/core/src/kvstore/mod.rs
@@ -681,7 +681,7 @@ impl KvStoreApiClient {
 mod tests {
     use super::*;
     use crate::{KvStoreConfig, QuicknodeSdk, SdkFullConfig};
-    use wiremock::matchers::{method, path};
+    use wiremock::matchers::{body_json, method, path};
     use wiremock::{Mock, MockServer, ResponseTemplate};
 
     fn make_sdk(base_url: String) -> QuicknodeSdk {
@@ -938,6 +938,59 @@ mod tests {
         assert!(matches!(err, SdkError::Api { .. }));
     }
 
+    // Wire-inspection regressions: confirm that addSets and deleteSets reach
+    // the wire under the names the API expects, so any future serde rename of
+    // these fields fails loudly.
+    #[tokio::test]
+    async fn bulk_sets_wire_body_add_sets() {
+        let server = MockServer::start().await;
+        Mock::given(method("POST"))
+            .and(path("/sets/bulk"))
+            .and(body_json(serde_json::json!({
+                "add_sets": {"k1": "v1"}
+            })))
+            .respond_with(
+                ResponseTemplate::new(201)
+                    .set_body_json(serde_json::json!({"code": 0, "msg": "ok", "data": null})),
+            )
+            .mount(&server)
+            .await;
+        let sdk = make_sdk(format!("{}/", server.uri()));
+        let mut add = HashMap::new();
+        add.insert("k1".to_string(), "v1".to_string());
+        sdk.kvstore
+            .bulk_sets(&BulkSetsParams {
+                add_sets: Some(add),
+                delete_sets: None,
+            })
+            .await
+            .unwrap();
+    }
+
+    #[tokio::test]
+    async fn bulk_sets_wire_body_delete_sets() {
+        let server = MockServer::start().await;
+        Mock::given(method("POST"))
+            .and(path("/sets/bulk"))
+            .and(body_json(serde_json::json!({
+                "delete_sets": ["k1", "k2"]
+            })))
+            .respond_with(
+                ResponseTemplate::new(201)
+                    .set_body_json(serde_json::json!({"code": 0, "msg": "ok", "data": null})),
+            )
+            .mount(&server)
+            .await;
+        let sdk = make_sdk(format!("{}/", server.uri()));
+        sdk.kvstore
+            .bulk_sets(&BulkSetsParams {
+                add_sets: None,
+                delete_sets: Some(vec!["k1".to_string(), "k2".to_string()]),
+            })
+            .await
+            .unwrap();
+    }
+
     #[tokio::test]
     async fn delete_set_success() {
         let server = MockServer::start().await;
@@ -1192,6 +1245,37 @@ mod tests {
             .unwrap();
     }
 
+    // Wire-inspection regression: confirm addItems/removeItems reach the wire
+    // under the names the API expects, so any future serde rename of these
+    // fields fails loudly.
+    #[tokio::test]
+    async fn update_list_wire_body() {
+        let server = MockServer::start().await;
+        Mock::given(method("PATCH"))
+            .and(path("/lists/my-list"))
+            .and(body_json(serde_json::json!({
+                "add_items": ["c"],
+                "remove_items": ["a"]
+            })))
+            .respond_with(
+                ResponseTemplate::new(200)
+                    .set_body_json(serde_json::json!({"code": 0, "msg": "ok", "data": null})),
+            )
+            .mount(&server)
+            .await;
+        let sdk = make_sdk(format!("{}/", server.uri()));
+        sdk.kvstore
+            .update_list(
+                "my-list",
+                &UpdateListParams {
+                    add_items: Some(vec!["c".to_string()]),
+                    remove_items: Some(vec!["a".to_string()]),
+                },
+            )
+            .await
+            .unwrap();
+    }
+
     #[tokio::test]
     async fn update_list_api_error() {
         let server = MockServer::start().await;
diff --git a/crates/core/src/streams/mod.rs b/crates/core/src/streams/mod.rs
index edb83be..5b107d2 100644
--- a/crates/core/src/streams/mod.rs
+++ b/crates/core/src/streams/mod.rs
@@ -944,7 +944,7 @@ mod tests {
             network: "ethereum-mainnet".to_string(),
             dataset: StreamDataset::Block,
             block: "17811625".to_string(),
-            filter_function: None,
+            filter_function: "ZnVuY3Rpb24gbWFpbihkYXRhKSB7IHJldHVybiBkYXRhOyB9".to_string(),
             filter_language: None,
             address_book_config: None,
         };
@@ -965,7 +965,7 @@ mod tests {
             network: "ethereum-mainnet".to_string(),
             dataset: StreamDataset::Block,
             block: "17811625".to_string(),
-            filter_function: None,
+            filter_function: "ZnVuY3Rpb24gbWFpbihkYXRhKSB7IHJldHVybiBkYXRhOyB9".to_string(),
             filter_language: None,
             address_book_config: None,
         };
diff --git a/crates/core/src/streams/stream.rs b/crates/core/src/streams/stream.rs
index 156c923..7213cbe 100644
--- a/crates/core/src/streams/stream.rs
+++ b/crates/core/src/streams/stream.rs
@@ -806,9 +806,8 @@ pub struct TestFilterParams {
     pub dataset: StreamDataset,
     /// Specific block number to feed into the filter for the test.
     pub block: String,
-    /// Base64-encoded filter function to evaluate.
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub filter_function: Option<String>,
+    /// Base64-encoded filter function to evaluate. Required by the API. To inspect raw block data with no transformation, supply a base64-encoded identity function such as `function main(d){return d;}`.
+    pub filter_function: String,
     /// Language the filter function is written in.
     #[serde(skip_serializing_if = "Option::is_none")]
     pub filter_language: Option<FilterLanguage>,
diff --git a/crates/core/src/webhooks/mod.rs b/crates/core/src/webhooks/mod.rs
index dadf52c..0bbd919 100644
--- a/crates/core/src/webhooks/mod.rs
+++ b/crates/core/src/webhooks/mod.rs
@@ -712,6 +712,34 @@ mod tests {
         assert_eq!(resp.id, "wh-1234-5678");
     }
 
+    // Wire-inspection regression: confirm that `name` reaches the wire when
+    // supplied so any future serde rename/drop of the field fails loudly.
+    #[tokio::test]
+    async fn update_webhook_template_wire_body_includes_name() {
+        use wiremock::matchers::body_partial_json;
+        let server = MockServer::start().await;
+        Mock::given(method("PATCH"))
+            .and(path_regex("/webhooks/test-id/template/evmWalletFilter"))
+            .and(body_partial_json(serde_json::json!({"name": "new-name"})))
+            .respond_with(ResponseTemplate::new(200).set_body_json(webhook_response_json()))
+            .mount(&server)
+            .await;
+        let sdk = make_sdk(format!("{}/", server.uri()));
+        let template_args = TemplateArgs::EvmWalletFilter(EvmWalletFilterTemplate {
+            wallets: vec!["0xabc".to_string()],
+        });
+        let params = UpdateWebhookTemplateParams {
+            name: Some("new-name".to_string()),
+            notification_email: None,
+            destination_attributes: None,
+            template_args,
+        };
+        sdk.webhooks
+            .update_webhook_template("test-id", &params)
+            .await
+            .unwrap();
+    }
+
     #[tokio::test]
     async fn update_webhook_template_api_error() {
         let server = MockServer::start().await;
diff --git a/crates/python/src/lib.rs b/crates/python/src/lib.rs
index 8d792f5..ae0da52 100644
--- a/crates/python/src/lib.rs
+++ b/crates/python/src/lib.rs
@@ -1729,7 +1729,7 @@ impl StreamsApiClient {
     /// Runs a filter function against a specified block on a given network and
     /// dataset, returning the filter's output so it can be validated before
     /// being attached to a live stream.
-    #[pyo3(signature = (network, dataset, block, filter_function=None, filter_language=None))]
+    #[pyo3(signature = (network, dataset, block, filter_function, filter_language=None))]
     #[gen_stub(override_return_type(
         type_repr = "typing.Coroutine[typing.Any, typing.Any, TestFilterResponse]"
     ))]
@@ -1739,7 +1739,7 @@ impl StreamsApiClient {
         network: String,
         dataset: String,
         block: String,
-        filter_function: Option<String>,
+        filter_function: String,
         filter_language: Option<String>,
     ) -> PyResult<Bound<'py, PyAny>> {
         let client = self.inner.clone();
diff --git a/crates/ruby/src/lib.rs b/crates/ruby/src/lib.rs
index 75e5aca..4b49dac 100644
--- a/crates/ruby/src/lib.rs
+++ b/crates/ruby/src/lib.rs
@@ -1367,7 +1367,7 @@ impl StreamsApiClient {
             network: hash_require_string(&opts, "network")?,
             dataset,
             block: hash_require_string(&opts, "block")?,
-            filter_function: hash_get_string(&opts, "filter_function")?,
+            filter_function: hash_require_string(&opts, "filter_function")?,
             filter_language,
             address_book_config: None,
         };
diff --git a/npm/README.md b/npm/README.md
index 462eec6..9b0e694 100644
--- a/npm/README.md
+++ b/npm/README.md
@@ -796,7 +796,7 @@ Returns metric series for an endpoint over a time period.
 
 **Parameters**: `id` (endpoint id, required); body: `period` (`"hour"` | `"day"` | `"week"` | `"month"`), `metric` (e.g. `"method_calls_over_time"`, `"response_status_breakdown"`).
 
-**Returns**: `GetEndpointMetricsResponse` with `data: EndpointMetric[]`.
+**Returns**: `GetEndpointMetricsResponse` with `data: EndpointMetric[]`. Each `EndpointMetric` has a `tag: string[]` and a `data: [timestamp, value][]`. Single-axis series (e.g. `response_time_over_time` with a percentile) come back as a one-element tag like `["p95"]`; multi-axis series come back as `["network", "arbitrum-mainnet"]`.
 
 ```typescript
 // Node.js
@@ -812,7 +812,7 @@ Returns account-level metric series. Supports an optional `percentile` (e.g. `"p
 
 **Parameters**: `period` (required), `metric` (required), `percentile` (string, optional).
 
-**Returns**: `GetAccountMetricsResponse` with `data: EndpointMetric[]`.
+**Returns**: `GetAccountMetricsResponse` with `data: EndpointMetric[]`. See `getEndpointMetrics` above for the `tag: string[]` shape.
 
 ```typescript
 // Node.js
diff --git a/npm/examples/admin.ts b/npm/examples/admin.ts
index 405684b..a36f418 100644
--- a/npm/examples/admin.ts
+++ b/npm/examples/admin.ts
@@ -29,6 +29,13 @@ async function main() {
     console.log(`account tags: ${tags.data.tags.length}`);
   }
 
+  const metrics = await qn.admin.getAccountMetrics({
+    period: "day",
+    metric: "credits_over_time",
+  });
+  const firstTag = metrics.data[0]?.tag.join(":") ?? "<none>";
+  console.log(`getAccountMetrics: ${metrics.data.length} series, first tag: ${firstTag}`);
+
   if (response.data.length > 0) {
     const sec = await qn.admin.getEndpointSecurity(response.data[0].id);
     console.log(`getEndpointSecurity: has_data=${sec.data !== undefined && sec.data !== null}`);
diff --git a/npm/index.d.ts b/npm/index.d.ts
index c4ebbbe..91db289 100644
--- a/npm/index.d.ts
+++ b/npm/index.d.ts
@@ -208,8 +208,12 @@ export interface GetAccountMetricsRequest {
 export interface EndpointMetric {
   /** Data points, each as `[timestamp, value]`. */
   data: Array<Array<number>>
-  /** Human-readable tag identifying the series. */
-  tag: string
+  /**
+   * Tag identifying the series. Single-axis metrics return a one-element
+   * vector (e.g. `["total"]`, `["p95"]`); multi-axis metrics return the
+   * key/value pair (e.g. `["network", "arbitrum-mainnet"]`).
+   */
+  tag: Array<string>
 }
 /** Response from `get_endpoint_metrics`. */
 export interface GetEndpointMetricsResponse {
@@ -1420,8 +1424,8 @@ export interface TestFilterParams {
   dataset: StreamDataset
   /** Specific block number to feed into the filter for the test. */
   block: string
-  /** Base64-encoded filter function to evaluate. */
-  filterFunction?: string
+  /** Base64-encoded filter function to evaluate. Required by the API. To inspect raw block data with no transformation, supply a base64-encoded identity function such as `function main(d){return d;}`. */
+  filterFunction: string
   /** Language the filter function is written in. */
   filterLanguage?: FilterLanguage
   /** Address book linked to the filter, if any. */
diff --git a/python/README.md b/python/README.md
index 4aafae0..c7a62c4 100644
--- a/python/README.md
+++ b/python/README.md
@@ -802,7 +802,7 @@ Returns metric series for an endpoint over a time period.
 
 **Parameters**: `id` (endpoint id, required); body: `period` (`"hour"` | `"day"` | `"week"` | `"month"`), `metric` (e.g. `"method_calls_over_time"`, `"response_status_breakdown"`).
 
-**Returns**: `GetEndpointMetricsResponse` with `data: EndpointMetric[]`.
+**Returns**: `GetEndpointMetricsResponse` with `data: list[EndpointMetric]`. Each `EndpointMetric` has a `tag: list[str]` and a `data: list[list[int]]` of `[timestamp, value]` pairs. Single-axis series (e.g. `response_time_over_time` with a percentile) come back as a one-element tag like `["p95"]`; multi-axis series come back as `["network", "arbitrum-mainnet"]`.
 
 ```python
 # Python
@@ -819,7 +819,7 @@ Returns account-level metric series. Supports an optional `percentile` (e.g. `"p
 
 **Parameters**: `period` (required), `metric` (required), `percentile` (string, optional).
 
-**Returns**: `GetAccountMetricsResponse` with `data: EndpointMetric[]`.
+**Returns**: `GetAccountMetricsResponse` with `data: list[EndpointMetric]`. See `get_endpoint_metrics` above for the `tag: list[str]` shape.
 
 ```python
 # Python
diff --git a/python/examples/admin.py b/python/examples/admin.py
index bc83ace..842a108 100644
--- a/python/examples/admin.py
+++ b/python/examples/admin.py
@@ -32,6 +32,12 @@ async def main():
     if tags.data is not None:
         print(f"account tags: {len(tags.data.tags)}")
 
+    metrics = await qn.admin.get_account_metrics(
+        period="day", metric="credits_over_time"
+    )
+    first_tag = ":".join(metrics.data[0].tag) if metrics.data else "<none>"
+    print(f"get_account_metrics: {len(metrics.data)} series, first tag: {first_tag}")
+
     if response.data:
         sec = await qn.admin.get_endpoint_security(response.data[0].id)
         print(f"get_endpoint_security: has_data={sec.data is not None}")
diff --git a/python/sdk/_core/__init__.pyi b/python/sdk/_core/__init__.pyi
index eb0dc58..4e76384 100644
--- a/python/sdk/_core/__init__.pyi
+++ b/python/sdk/_core/__init__.pyi
@@ -2024,14 +2024,18 @@ class EndpointMetric:
         Data points, each as `[timestamp, value]`.
         """
     @property
-    def tag(self) -> builtins.str:
+    def tag(self) -> builtins.list[builtins.str]:
         r"""
-        Human-readable tag identifying the series.
+        Tag identifying the series. Single-axis metrics return a one-element
+        vector (e.g. `["total"]`, `["p95"]`); multi-axis metrics return the
+        key/value pair (e.g. `["network", "arbitrum-mainnet"]`).
         """
     @tag.setter
-    def tag(self, value: builtins.str) -> None:
+    def tag(self, value: builtins.list[builtins.str]) -> None:
         r"""
-        Human-readable tag identifying the series.
+        Tag identifying the series. Single-axis metrics return a one-element
+        vector (e.g. `["total"]`, `["p95"]`); multi-axis metrics return the
+        key/value pair (e.g. `["network", "arbitrum-mainnet"]`).
         """
 
 @typing.final
@@ -5211,7 +5215,7 @@ class StreamsApiClient:
         r"""
         Pauses a stream by ID, halting delivery until it is activated again.
         """
-    def test_filter(self, network: builtins.str, dataset: builtins.str, block: builtins.str, filter_function: typing.Optional[builtins.str] = None, filter_language: typing.Optional[builtins.str] = None) -> typing.Coroutine[typing.Any, typing.Any, TestFilterResponse]:
+    def test_filter(self, network: builtins.str, dataset: builtins.str, block: builtins.str, filter_function: builtins.str, filter_language: typing.Optional[builtins.str] = None) -> typing.Coroutine[typing.Any, typing.Any, TestFilterResponse]:
         r"""
         Runs a filter function against a specified block on a given network and
         dataset, returning the filter's output so it can be validated before
diff --git a/ruby/README.md b/ruby/README.md
index e70b1e4..bb5c938 100644
--- a/ruby/README.md
+++ b/ruby/README.md
@@ -791,7 +791,7 @@ Returns metric series for an endpoint over a time period.
 
 **Parameters**: `id` (endpoint id, required); body: `period` (`"hour"` | `"day"` | `"week"` | `"month"`), `metric` (e.g. `"method_calls_over_time"`, `"response_status_breakdown"`).
 
-**Returns**: `GetEndpointMetricsResponse` with `data: EndpointMetric[]`.
+**Returns**: `GetEndpointMetricsResponse` (as a `Hashie::Mash`) with `data: Array<EndpointMetric>`. Each `EndpointMetric` has `tag: Array<String>` and `data: Array<Array<Integer>>` of `[timestamp, value]` pairs. Single-axis series (e.g. `response_time_over_time` with a percentile) come back as a one-element tag like `["p95"]`; multi-axis series come back as `["network", "arbitrum-mainnet"]`.
 
 ```ruby
 # Ruby
@@ -808,7 +808,7 @@ Returns account-level metric series. Supports an optional `percentile` (e.g. `"p
 
 **Parameters**: `period` (required), `metric` (required), `percentile` (string, optional).
 
-**Returns**: `GetAccountMetricsResponse` with `data: EndpointMetric[]`.
+**Returns**: `GetAccountMetricsResponse` (as a `Hashie::Mash`) with `data: Array<EndpointMetric>`. See `get_endpoint_metrics` above for the `tag: Array<String>` shape.
 
 ```ruby
 # Ruby
diff --git a/ruby/examples/admin_e2e.rb b/ruby/examples/admin_e2e.rb
index 2fb2cf3..722fc74 100644
--- a/ruby/examples/admin_e2e.rb
+++ b/ruby/examples/admin_e2e.rb
@@ -56,7 +56,8 @@
 puts "list_tags: #{resp.dig(:data, :tags)&.length || 0} tags"
 
 resp = qn.admin.get_account_metrics(period: "day", metric: "requests")
-puts "get_account_metrics: #{resp[:data].length} series"
+first_tag = resp[:data].first&.dig(:tag)&.join(":") || "<none>"
+puts "get_account_metrics: #{resp[:data].length} series, first tag: #{first_tag}"
 
 resp = qn.admin.list_invoices
 puts "list_invoices: #{resp[:data].inspect}"
@@ -122,7 +123,8 @@
 sleep 1
 
 resp = qn.admin.get_endpoint_metrics(id: endpoint_id, period: "day", metric: "credits_over_time")
-puts "get_endpoint_metrics: #{resp[:data].length} series"
+first_tag = resp[:data].first&.dig(:tag)&.join(":") || "<none>"
+puts "get_endpoint_metrics: #{resp[:data].length} series, first tag: #{first_tag}"
 
 # ── Security options ──────────────────────────────────────────────────────────
 
diff --git a/ruby/sig/quicknode_sdk.rbs b/ruby/sig/quicknode_sdk.rbs
index 0ef4ab4..15a6f77 100644
--- a/ruby/sig/quicknode_sdk.rbs
+++ b/ruby/sig/quicknode_sdk.rbs
@@ -118,7 +118,7 @@ module QuicknodeSdk
     def delete_stream: (id: String) -> void
     def activate_stream: (id: String) -> void
     def pause_stream: (id: String) -> void
-    def test_filter: (network: String, dataset: String, block: String, ?filter_function: String, ?filter_language: String) -> untyped
+    def test_filter: (network: String, dataset: String, block: String, filter_function: String, ?filter_language: String) -> untyped
     def get_enabled_count: (?stream_type: String) -> untyped
   end