From 15c4889497b96037e41019a8f43090af841b36ec Mon Sep 17 00:00:00 2001
From: furszy <matiasfurszyfer@protonmail.com>
Date: Thu, 5 Mar 2026 17:29:27 -0300
Subject: [PATCH] index: document TxoSpenderIndex::FindSpender

Hard to know what a returned std::Expected(std::nullopt) mean
if it is not documented anywhere.
---
 src/index/txospenderindex.h | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/src/index/txospenderindex.h b/src/index/txospenderindex.h
index 42e25bcd7fd..35ca30d8b31 100644
--- a/src/index/txospenderindex.h
+++ b/src/index/txospenderindex.h
@@ -55,6 +55,16 @@ protected:
 public:
     explicit TxoSpenderIndex(std::unique_ptr<interfaces::Chain> chain, size_t n_cache_size, bool f_memory = false, bool f_wipe = false);
 
+    /**
+     * Search the index for a transaction that spends the given outpoint.
+     *
+     * @param[in] txo  The outpoint to search for.
+     *
+     * @return  std::nullopt               if the outpoint has not been spent on-chain.
+     *          std::optional{TxoSpender}  if the output has been spent on-chain. Contains the spending transaction
+     *                                     and the block it was confirmed in.
+     *          util::Unexpected{error}    if something unexpected happened (i.e. disk or deserialization error).
+     */
     util::Expected<std::optional<TxoSpender>, std::string> FindSpender(const COutPoint& txo) const;
 };