Add CoinJoinXT topic page

data/blog/seventeenth-wave-of-bitcoin-grants.mdx

@@ -74,7 +74,7 @@ License: MIT
 [JoinMarket protocol]: https://github.com/JoinMarket-Org/joinmarket-clientserver
 [Neutrino]: https://github.com/lightninglabs/neutrino?tab=readme-ov-file#neutrino-privacy-preserving-bitcoin-light-client
 [nostr relay]: https://github.com/nostr-protocol/nostr?tab=readme-ov-file#how-it-works
-[CoinJoinXT]: https://en.bitcoin.it/wiki/CoinJoinXT
+[CoinJoinXT]: /topics/coinjoinxt
 [Lightning]: https://lightning.network/
 [ecash]: https://cashu.space/
 [joinmarket-ng/joinmarket-ng]: https://github.com/m0wer/joinmarket-ng

data/topics/coinjoinxt.mdx

@@ -0,0 +1,18 @@
+---
+title: 'CoinJoinXT'
+summary: 'A proposed multi-transaction CoinJoin design that spreads a collaborative spend across a graph of linked transactions to improve on-chain privacy.'
+category: 'Privacy'
+aliases: ['CoinJoin XT', 'proposed transaction graph', 'PTG']
+---
+
+CoinJoinXT is a proposed Bitcoin privacy protocol that extends the basic idea behind [CoinJoin](/topics/coinjoin). Instead of combining everyone into one shared transaction, participants build a connected set of transactions, often described as a proposed transaction graph, that moves funds through intermediate outputs and returns each participant the value they put in.
+
+That structure aims to make the resulting on-chain footprint look less like a single obvious mix. If the graph blends in with ordinary transaction activity, chain analysis has a harder time identifying where the coordinated protocol starts and ends. Some designs also preserve CoinJoin-style ambiguity even after the construction is recognized, because observers still cannot reliably match equal-valued outputs back to specific inputs.
+
+The tradeoffs are extra block space, more coordination, and stricter transaction requirements. Early CoinJoinXT designs leaned on [SegWit][/topics/segwit] to avoid transaction malleability problems, and later writeups describe variants that would benefit from [Schnorr][/topics/taproot]-style aggregated signing. CoinJoinXT remains a research direction rather than a widely deployed wallet feature, though JoinMarket contributors and other privacy researchers have published design notes and proof-of-concept code.
+
+## References
+
+- [en.bitcoin.it: CoinJoinXT](https://en.bitcoin.it/wiki/CoinJoinXT)
+- [Chaumian CoinJoinXT](https://zmnscpxj.github.io/bitcoin/coinjoinxt.html)
+- [AdamISZ/CoinJoinXT-POC](https://github.com/AdamISZ/CoinJoinXT-POC)