joinmarket: fix for NixOS 25.11

Temporarily add nixpkgs-25.05 for joinmarket (see code comment).

flake.lock

@@ -58,6 +58,22 @@
         "type": "github"
       }
     },
+    "nixpkgs-25_05": {
+      "locked": {
+        "lastModified": 1766014764,
+        "narHash": "sha256-+73VffE5GP5fvbib6Hs1Su6LehG+9UV1Kzs90T2gBLA=",
+        "owner": "NixOS",
+        "repo": "nixpkgs",
+        "rev": "2b0d2b456e4e8452cf1c16d00118d145f31160f9",
+        "type": "github"
+      },
+      "original": {
+        "owner": "NixOS",
+        "ref": "nixos-25.05",
+        "repo": "nixpkgs",
+        "type": "github"
+      }
+    },
     "nixpkgs-unstable": {
       "locked": {
         "lastModified": 1766314097,
@@ -79,6 +95,7 @@
         "extra-container": "extra-container",
         "flake-utils": "flake-utils",
         "nixpkgs": "nixpkgs",
+        "nixpkgs-25_05": "nixpkgs-25_05",
         "nixpkgs-unstable": "nixpkgs-unstable"
       }
     },

flake.nix

@@ -7,6 +7,7 @@
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.11";
     nixpkgs-unstable.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    nixpkgs-25_05.url = "github:NixOS/nixpkgs/nixos-25.05";
     flake-utils.url = "github:numtide/flake-utils";
     extra-container = {
       url = "github:erikarvstedt/extra-container/0.13";
@@ -15,7 +16,7 @@
     };
   };
 
-  outputs = { self, nixpkgs, nixpkgs-unstable, flake-utils, ... }:
+  outputs = { self, nixpkgs, nixpkgs-unstable, nixpkgs-25_05, flake-utils, ... }:
     let
       supportedSystems = [
         "x86_64-linux"
@@ -33,8 +34,9 @@
           system
           , pkgs ? nixpkgs.legacyPackages.${system}
           , pkgsUnstable ? nixpkgs-unstable.legacyPackages.${system}
+          , pkgs-25_05 ? nixpkgs-25_05.legacyPackages.${system}
         }:
-          import ./pkgs { inherit pkgs pkgsUnstable; };
+          import ./pkgs { inherit pkgs pkgsUnstable pkgs-25_05; };
 
         test = {
           inherit (test) scenarios;
@@ -95,6 +97,8 @@
           "nixops19_09"
           "pinned"
           "generate-secrets"
+          "nbPython3Packages"
+          "nbPython3PackagesJoinmarket"
         ]) // {
           inherit (import ./examples/qemu-vm/minimal-vm.nix self pkgs system)
             # A simple demo VM.

helper/update-flake.nix

@@ -64,7 +64,7 @@ in rec {
     toLines = pkgs: builtins.concatStringsSep "\n    " (builtins.attrNames pkgs);
   in ''
     # This file is generated by ../helper/update-flake.nix
-    pkgs: pkgsUnstable:
+    pkgs: pkgsUnstable: pkgs-25_05:
     {
       inherit (pkgs)
         ${toLines versions.stable};
@@ -72,7 +72,7 @@ in rec {
       inherit (pkgsUnstable)
         ${toLines versions.unstable};
 
-      inherit pkgs pkgsUnstable;
+      inherit pkgs pkgsUnstable pkgs-25_05;
     }
   '';
 }

pkgs/default.nix

@@ -8,6 +8,11 @@ in
     config = {};
     overlays = [];
   }
+, pkgs-25_05 ? import nixpkgsPinned.nixpkgs-25_05 {
+    inherit (pkgs.stdenv.hostPlatform) system;
+    config = {};
+    overlays = [];
+  }
 }:
 let self = {
   clightning-rest = pkgs.callPackage ./clightning-rest { inherit (self) fetchNodeModules; };
@@ -43,7 +48,7 @@ let self = {
   generate-secrets = import ./generate-secrets-deprecated.nix;
   nixops19_09 = pkgs.callPackage ./nixops { };
 
-  pinned = import ./pinned.nix pkgs pkgsUnstable;
+  pinned = import ./pinned.nix pkgs pkgsUnstable pkgs-25_05;
 
   modulesPkgs = self // self.pinned;
 }; in self

pkgs/joinmarket/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, lib, fetchFromGitHub, python3, nbPython3PackagesJoinmarket }:
+{ stdenv, lib, fetchFromGitHub, nbPython3PackagesJoinmarket }:
 
 let
   # Note:
@@ -18,7 +18,7 @@ let
     matplotlib # for ob-watcher
   ];
 
-  pythonEnv = python3.withPackages (_: runtimePackages);
+  pythonEnv = nbPython3PackagesJoinmarket.python.withPackages (_: runtimePackages);
 in
 stdenv.mkDerivation {
   pname = "joinmarket";

pkgs/nixpkgs-pinned.nix

@@ -17,4 +17,5 @@ in
 {
   nixpkgs = fetch lockedInputs.nixpkgs;
   nixpkgs-unstable = fetch lockedInputs.nixpkgs-unstable;
+  nixpkgs-25_05 = fetch lockedInputs.nixpkgs-25_05;
 }

pkgs/pinned.nix

@@ -1,5 +1,5 @@
 # This file is generated by ../helper/update-flake.nix
-pkgs: pkgsUnstable:
+pkgs: pkgsUnstable: pkgs-25_05:
 {
   inherit (pkgs)
     bitcoin
@@ -21,5 +21,5 @@ pkgs: pkgsUnstable:
   inherit (pkgsUnstable)
     ;
 
-  inherit pkgs pkgsUnstable;
+  inherit pkgs pkgsUnstable pkgs-25_05;
 }

pkgs/python-packages/default.nix

@@ -21,18 +21,27 @@ rec {
       sha256 = callPackage ./sha256 {};
 
       joinmarket = callPackage ./joinmarket { inherit (nbPkgs.joinmarket) version src; };
-
-      ## Specific versions of packages that already exist in nixpkgs
-
-      # autobahn 20.12.3, required by joinmarketclient
-      autobahn = callPackage ./specific-versions/autobahn.nix {};
     };
 
   nbPython3Packages = (python3.override {
     packageOverrides = pyPkgsOverrides;
   }).pkgs;
 
-  nbPython3PackagesJoinmarket = nbPython3Packages;
+  # joinmarket requires cython 3.0 via pkg bencoder.pyx.
+  # The python pkgs from nixpkgs-25.11 default to cython 3.1.
+  # Downgrading to 3.0 causes mass rebuilds, so we use python pkgs from nixpkgs-25.05 for joinmarket.
+  # The nixpkgs-25.05 dependency will be removed with the next joinmarket update.
+  # https://github.com/JoinMarket-Org/joinmarket-clientserver/issues/1787
+  nbPython3PackagesJoinmarket =
+    (nbPkgs.pinned.pkgs-25_05.python3.override {
+      packageOverrides = self: super:
+        (pyPkgsOverrides self super) // {
+          ## Specific versions of packages that already exist in nixpkgs
+
+          # autobahn 20.12.3, required by joinmarketclient
+          autobahn = self.callPackage ./specific-versions/autobahn.nix {};
+        };
+    }).pkgs;
 
   # Re-enable pkgs `hwi`, `trezor` that are unaffected by `CVE-2024-23342` because
   # they don't use python pkg `ecdsa` for signing.