implement helper for specifying per-request tracing

src/qdrant_client/mod.rs

@@ -212,6 +212,27 @@ impl Qdrant {
         Ok(result)
     }
 
+    /// Create a lightweight clone of this client with an additional header.
+    ///
+    /// The returned client shares the same connection pool but sends
+    /// the extra header with every request. Useful for per-request
+    /// tracing IDs or other contextual metadata.
+    ///
+    /// ```no_run
+    /// use qdrant_client::Qdrant;
+    ///
+    ///# async fn example(client: &Qdrant) -> Result<(), qdrant_client::QdrantError> {
+    /// let traced = client.with_header("x-request-id", "abc-123");
+    /// // traced shares the same connection pool, but adds the header to every request
+    ///# Ok(())
+    ///# }
+    /// ```
+    pub fn with_header(&self, key: impl Into<String>, value: impl Into<String>) -> Self {
+        let mut clone = self.clone();
+        clone.config.custom_headers.push((key.into(), value.into()));
+        clone
+    }
+
     /// Health check.
     ///
     /// Do a health check and fetch server information such as the current version and commit.

tests/snippet_tests/mod.rs

@@ -1,7 +1,6 @@
 mod test_batch_update;
 mod test_clear_payload;
 mod test_collection_exists;
-mod test_config_headers;
 mod test_count_points;
 mod test_create_collection;
 mod test_create_collection_with_bq;
@@ -21,7 +20,6 @@ mod test_delete_snapshot;
 mod test_delete_vectors;
 mod test_discover_batch_points;
 mod test_discover_points;
-mod test_external_api_keys;
 mod test_facets;
 mod test_get_collection;
 mod test_get_collection_aliases;
@@ -59,3 +57,4 @@ mod test_upsert_points;
 mod test_upsert_points_fallback_shard_key;
 mod test_upsert_points_insert_only;
 mod test_upsert_points_with_condition;
+mod test_with_header;

tests/snippet_tests/test_with_header.rs

@@ -0,0 +1,32 @@
+
+#[tokio::test]
+async fn test_with_header() {
+    async fn with_header() -> Result<(), Box<dyn std::error::Error>> {
+      // WARNING: This is a generated test snippet.
+      // Please, modify the snippet in the `../snippets/with_header.rs` file
+        use qdrant_client::Qdrant;
+
+        let client = Qdrant::from_url("http://localhost:6334")
+            .header("x-base", "base-value")
+            .skip_compatibility_check()
+            .build()
+            .unwrap();
+
+        let traced = client.with_header("x-request-id", "abc-123");
+
+        assert_eq!(
+            traced.config.custom_headers,
+            vec![
+                ("x-base".to_string(), "base-value".to_string()),
+                ("x-request-id".to_string(), "abc-123".to_string()),
+            ]
+        );
+        // Original still has only the base header
+        assert_eq!(
+            client.config.custom_headers,
+            vec![("x-base".to_string(), "base-value".to_string())]
+        );
+        Ok(())
+    }
+    let _ = with_header().await;
+}

tests/snippets/with_header.rs

@@ -0,0 +1,22 @@
+use qdrant_client::Qdrant;
+
+let client = Qdrant::from_url("http://localhost:6334")
+    .header("x-base", "base-value")
+    .skip_compatibility_check()
+    .build()
+    .unwrap();
+
+let traced = client.with_header("x-request-id", "abc-123");
+
+assert_eq!(
+    traced.config.custom_headers,
+    vec![
+        ("x-base".to_string(), "base-value".to_string()),
+        ("x-request-id".to_string(), "abc-123".to_string()),
+    ]
+);
+// Original still has only the base header
+assert_eq!(
+    client.config.custom_headers,
+    vec![("x-base".to_string(), "base-value".to_string())]
+);