fix(models): preserve duplicate request headers

crates/yaak-models/src/queries/folders.rs

@@ -1,4 +1,4 @@
-use super::conflict_free_name;
+use super::{conflict_free_name, merge_headers};
 use crate::client_db::ClientDb;
 use crate::connection_or_tx::ConnectionOrTx;
 use crate::error::Result;
@@ -144,9 +144,7 @@ impl<'a> ClientDb<'a> {
             headers.append(&mut workspace_headers);
         }
 
-        headers.append(&mut folder.headers.clone());
-
-        Ok(headers)
+        Ok(merge_headers(headers, folder.headers.clone()))
     }
 
     pub fn resolve_settings_for_folder(

crates/yaak-models/src/queries/grpc_requests.rs

@@ -1,4 +1,4 @@
-use super::{conflict_free_name, dedupe_headers};
+use super::{conflict_free_name, merge_headers};
 use crate::client_db::ClientDb;
 use crate::error::Result;
 use crate::models::{
@@ -110,9 +110,7 @@ impl<'a> ClientDb<'a> {
             metadata.append(&mut workspace_metadata);
         }
 
-        metadata.append(&mut grpc_request.metadata.clone());
-
-        Ok(dedupe_headers(metadata))
+        Ok(merge_headers(metadata, grpc_request.metadata.clone()))
     }
 
     pub fn resolve_settings_for_grpc_request(

crates/yaak-models/src/queries/http_requests.rs

@@ -1,4 +1,4 @@
-use super::{conflict_free_name, dedupe_headers};
+use super::{conflict_free_name, merge_headers};
 use crate::client_db::ClientDb;
 use crate::error::Result;
 use crate::models::{
@@ -96,9 +96,7 @@ impl<'a> ClientDb<'a> {
             headers.append(&mut workspace_headers);
         }
 
-        headers.append(&mut http_request.headers.clone());
-
-        Ok(dedupe_headers(headers))
+        Ok(merge_headers(headers, http_request.headers.clone()))
     }
 
     pub fn resolve_settings_for_http_request(
@@ -172,3 +170,44 @@ impl<'a> ClientDb<'a> {
         Ok(children)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::init_in_memory;
+    use crate::models::{HttpRequest, HttpRequestHeader};
+
+    #[test]
+    fn request_resolution_preserves_duplicate_request_headers() {
+        let (query_manager, _blob_manager, _rx) = init_in_memory().expect("Failed to init DB");
+        let db = query_manager.connect();
+        let workspace = db.list_workspaces().expect("Failed to list workspaces").remove(0);
+        let request = HttpRequest {
+            workspace_id: workspace.id,
+            headers: vec![
+                HttpRequestHeader {
+                    name: "Cookie".to_string(),
+                    value: "required=1".to_string(),
+                    ..Default::default()
+                },
+                HttpRequestHeader {
+                    enabled: false,
+                    name: "Cookie".to_string(),
+                    value: "optional=1".to_string(),
+                    ..Default::default()
+                },
+            ],
+            ..Default::default()
+        };
+
+        let resolved = db.resolve_headers_for_http_request(&request).expect("Failed to resolve");
+        let cookies = resolved
+            .iter()
+            .filter(|header| header.name.eq_ignore_ascii_case("cookie"))
+            .collect::<Vec<_>>();
+
+        assert_eq!(cookies.len(), 2);
+        assert_eq!(cookies[0].value, "required=1");
+        assert_eq!(cookies[1].value, "optional=1");
+        assert!(!cookies[1].enabled);
+    }
+}

crates/yaak-models/src/queries/mod.rs

@@ -28,21 +28,59 @@ pub(crate) use duplicate_name::conflict_free_name;
 const MAX_HISTORY_ITEMS: usize = 20;
 
 use crate::models::HttpRequestHeader;
-use std::collections::HashMap;
+use std::collections::HashSet;
 
-/// Deduplicate headers by name (case-insensitive), keeping the latest (most specific) value.
-/// Preserves the order of first occurrence for each header name.
-pub(crate) fn dedupe_headers(headers: Vec<HttpRequestHeader>) -> Vec<HttpRequestHeader> {
-    let mut index_by_name: HashMap<String, usize> = HashMap::new();
-    let mut deduped: Vec<HttpRequestHeader> = Vec::new();
-    for header in headers {
-        let key = header.name.to_lowercase();
-        if let Some(&idx) = index_by_name.get(&key) {
-            deduped[idx] = header;
-        } else {
-            index_by_name.insert(key, deduped.len());
-            deduped.push(header);
-        }
-    }
-    deduped
+/// Merge a more-specific header layer over its parent. Names in the child replace
+/// inherited values case-insensitively, while duplicates declared together in
+/// either layer remain independent entries.
+pub(crate) fn merge_headers(
+    mut parent: Vec<HttpRequestHeader>,
+    child: Vec<HttpRequestHeader>,
+) -> Vec<HttpRequestHeader> {
+    let child_names = child.iter().map(|header| header.name.to_lowercase()).collect::<HashSet<_>>();
+    parent.retain(|header| !child_names.contains(&header.name.to_lowercase()));
+    parent.extend(child);
+    parent
+}
+
+#[cfg(test)]
+mod tests {
+    use super::merge_headers;
+    use crate::models::HttpRequestHeader;
+
+    fn header(name: &str, value: &str) -> HttpRequestHeader {
+        HttpRequestHeader { name: name.to_string(), value: value.to_string(), ..Default::default() }
+    }
+
+    #[test]
+    fn preserves_duplicate_headers_declared_in_one_layer() {
+        let merged = merge_headers(
+            vec![header("Cookie", "inherited=1")],
+            vec![
+                header("Cookie", "required=1"),
+                header("cookie", "optional=1"),
+            ],
+        );
+
+        assert_eq!(
+            merged.iter().map(|header| header.value.as_str()).collect::<Vec<_>>(),
+            vec!["required=1", "optional=1"],
+        );
+    }
+
+    #[test]
+    fn child_names_override_parent_names_without_affecting_other_headers() {
+        let merged = merge_headers(
+            vec![header("Accept", "*/*"), header("X-Parent", "kept")],
+            vec![header("accept", "application/json")],
+        );
+
+        assert_eq!(
+            merged
+                .iter()
+                .map(|header| (header.name.as_str(), header.value.as_str()))
+                .collect::<Vec<_>>(),
+            vec![("X-Parent", "kept"), ("accept", "application/json")],
+        );
+    }
 }

crates/yaak-models/src/queries/websocket_requests.rs

@@ -1,4 +1,4 @@
-use super::{conflict_free_name, dedupe_headers};
+use super::{conflict_free_name, merge_headers};
 use crate::client_db::ClientDb;
 use crate::error::Result;
 use crate::models::{
@@ -103,13 +103,9 @@ impl<'a> ClientDb<'a> {
         &self,
         websocket_request: &WebsocketRequest,
     ) -> Result<Vec<HttpRequestHeader>> {
-        let workspace = self.get_workspace(&websocket_request.workspace_id)?;
-
         // Resolved headers should be from furthest to closest ancestor, to override logically.
         let mut headers = Vec::new();
 
-        headers.append(&mut workspace.headers.clone());
-
         if let Some(folder_id) = websocket_request.folder_id.clone() {
             let parent_folder = self.get_folder(&folder_id)?;
             let mut folder_headers = self.resolve_headers_for_folder(&parent_folder)?;
@@ -120,9 +116,7 @@ impl<'a> ClientDb<'a> {
             headers.append(&mut workspace_headers);
         }
 
-        headers.append(&mut websocket_request.headers.clone());
-
-        Ok(dedupe_headers(headers))
+        Ok(merge_headers(headers, websocket_request.headers.clone()))
     }
 
     pub fn resolve_settings_for_websocket_request(

crates/yaak-models/src/queries/workspaces.rs

@@ -1,3 +1,4 @@
+use super::merge_headers;
 use crate::blob_manager::BlobManager;
 use crate::client_db::ClientDb;
 use crate::error::Result;
@@ -144,9 +145,7 @@ impl<'a> ClientDb<'a> {
     }
 
     pub fn resolve_headers_for_workspace(&self, workspace: &Workspace) -> Vec<HttpRequestHeader> {
-        let mut headers = default_headers();
-        headers.extend(workspace.headers.clone());
-        headers
+        merge_headers(default_headers(), workspace.headers.clone())
     }
 
     pub fn resolve_settings_for_workspace(