feat: add height_of_hash to Requester API

Expose BlockTree::height_of_hash through the Requester channel.
Given a block hash, returns its height in the chain of most work,
or None if the hash is not in the chain.

Zero-cost local HashMap lookup — no network fetch needed.

Author: 0xsiddharthks

src/client.rs

@@ -221,6 +221,24 @@ impl Requester {
         rx.await.map_err(|_| ClientError::RecvError)
     }
 
+    /// Look up the height of a block hash in the locally synced chain of most work.
+    /// Returns `None` if the hash is not in the header chain.
+    ///
+    /// # Errors
+    ///
+    /// If the node has stopped running.
+    pub async fn height_of_hash(
+        &self,
+        hash: BlockHash,
+    ) -> Result<Option<u32>, ClientError> {
+        let (tx, rx) = tokio::sync::oneshot::channel::<Option<u32>>();
+        let request = ClientRequest::new(hash, tx);
+        self.ntx
+            .send(ClientMessage::HeightOfHash(request))
+            .map_err(|_| ClientError::SendError)?;
+        rx.await.map_err(|_| ClientError::RecvError)
+    }
+
     /// Check if the node is running.
     pub fn is_running(&self) -> bool {
         self.ntx.send(ClientMessage::NoOp).is_ok()

src/messages.rs

@@ -153,6 +153,8 @@ pub(crate) enum ClientMessage {
     GetBroadcastMinFeeRate(ClientRequest<(), FeeRate>),
     /// Get info on connections
     GetPeerInfo(ClientRequest<(), Vec<(AddrV2, ServiceFlags)>>),
+    /// Look up the height of a block hash in the chain of most work.
+    HeightOfHash(ClientRequest<BlockHash, Option<u32>>),
     /// Send an empty message to see if the node is running.
     NoOp,
 }

src/node.rs

@@ -268,6 +268,14 @@ impl Node {
                                     self.dialog.send_warning(Warning::ChannelDropped);
                                 };
                             }
+                            ClientMessage::HeightOfHash(request) => {
+                                let (hash, oneshot) = request.into_values();
+                                let height =
+                                    self.chain.header_chain.height_of_hash(hash);
+                                if oneshot.send(height).is_err() {
+                                    self.dialog.send_warning(Warning::ChannelDropped);
+                                };
+                            }
                             ClientMessage::NoOp => (),
                         }
                     }