{libtransmission_3,transmission_3{,-gtk,-qt,_noSystemd},torrential}: drop

nixos/modules/security/apparmor.nix

@@ -1,4 +1,5 @@
 {
+  options,
   config,
   lib,
   pkgs,
@@ -10,11 +11,6 @@ let
   cfg = config.security.apparmor;
   enabledPolicies = lib.filterAttrs (n: p: p.state != "disable") cfg.policies;
   buildPolicyPath = n: p: lib.defaultTo (pkgs.writeText n p.profile) p.path;
-
-  # Accessing submodule options when not defined results in an error thunk rather than a regular option object
-  # We can emulate the behavior of `<option>.isDefined` by attempting to evaluate it instead
-  # This is required because getting isDefined on a submodule is not possible in global module asserts.
-  submoduleOptionIsDefined = value: (builtins.tryEval value).success;
 in
 
 {
@@ -130,7 +126,9 @@ in
           # which does not recurse into sub-directories.
         }
         {
-          assertion = lib.xor (policyCfg.path != null) (submoduleOptionIsDefined policyCfg.profile);
+          assertion =
+            lib.xor (policyCfg.path != null)
+              options.security.apparmor.policies.valueMeta.attrs.${policyName}.configuration.options.profile.isDefined;
           message = "`security.apparmor.policies.\"${policyName}\"` must define exactly one of either path or profile.";
         }
       ]) cfg.policies

nixos/modules/services/torrent/transmission.nix

@@ -19,6 +19,8 @@ let
     optionalString
     optional
     mkDefault
+    mkOptionDefault
+    versionOlder
     escapeShellArgs
     optionalAttrs
     mkMerge
@@ -176,17 +178,12 @@ in
             };
             umask = mkOption {
               type = types.either types.int types.str;
-              default = if cfg.package == pkgs.transmission_3 then 18 else "022";
-              defaultText = literalExpression "if cfg.package == pkgs.transmission_3 then 18 else \"022\"";
+              default = "022";
               description = ''
                 Sets transmission's file mode creation mask.
                 See the {manpage}`umask(2)` manpage for more information.
                 Users who want their saved torrents to be world-writable
                 may want to set this value to 0/`"000"`.
-
-                Keep in mind, that if you are using Transmission 3, this has to
-                be passed as a base 10 integer, whereas Transmission 4 takes
-                an octal number in a string instead.
               '';
             };
             utp-enabled = mkOption {
@@ -222,10 +219,19 @@ in
         };
       };
 
-      package = mkPackageOption pkgs "transmission" {
-        default = "transmission_3";
-        example = "pkgs.transmission_4";
-      };
+      package =
+        mkPackageOption pkgs "transmission" {
+          default = "transmission_4";
+          example = "pkgs.transmission_4";
+        }
+        // {
+          defaultText = ''
+            if lib.versionAtLeast config.system.stateVersion "25.11" then
+              pkgs.transmission_4
+            else
+              «error message»
+          '';
+        };
 
       downloadDirPermissions = mkOption {
         type = with types; nullOr str;
@@ -331,6 +337,19 @@ in
   };
 
   config = mkIf cfg.enable {
+    services.transmission.package = mkIf (versionOlder config.system.stateVersion "25.11") (
+      mkOptionDefault (throw ''
+        `services.transmission.package` previously defaulted to
+        `pkgs.transmission_3`, which has been removed in favour
+        of `pkgs.transmission_4`.
+
+        Please set `services.transmission.package` to
+        `pkgs.transmission_4` explicitly. Note that upgrade
+        caused data loss for some users so backup is recommended
+        (see NixOS 24.11 release notes for details)
+      '')
+    );
+
     # Note that using systemd.tmpfiles would not work here
     # because it would fail when creating a directory
     # with a different owner than its parent directory, by saying:

nixos/tests/all-tests.nix

@@ -1537,8 +1537,7 @@ in
   traefik = runTestOn [ "aarch64-linux" "x86_64-linux" ] ./traefik.nix;
   trafficserver = runTest ./trafficserver.nix;
   transfer-sh = runTest ./transfer-sh.nix;
-  transmission_3 = handleTest ./transmission.nix { transmission = pkgs.transmission_3; };
-  transmission_4 = handleTest ./transmission.nix { transmission = pkgs.transmission_4; };
+  transmission_4 = handleTest ./transmission.nix { };
   trezord = runTest ./trezord.nix;
   trickster = runTest ./trickster.nix;
   trilium-server = runTestOn [ "x86_64-linux" ] ./trilium-server.nix;

nixos/tests/bittorrent.nix

@@ -6,12 +6,12 @@
 # which only works if the first client successfully uses the UPnP-IGD
 # protocol to poke a hole in the NAT.
 
-{ pkgs, ... }:
+{ lib, hostPkgs, ... }:
 
 let
 
   # Some random file to serve.
-  file = pkgs.hello.src;
+  file = hostPkgs.hello.src;
 
   internalRouterAddress = "192.168.3.1";
   internalClient1Address = "192.168.3.2";
@@ -23,7 +23,6 @@ let
   transmissionConfig =
     { pkgs, ... }:
     {
-      environment.systemPackages = [ pkgs.transmission_3 ];
       services.transmission = {
         enable = true;
         settings = {
@@ -37,7 +36,7 @@ in
 
 {
   name = "bittorrent";
-  meta = with pkgs.lib.maintainers; {
+  meta = with lib.maintainers; {
     maintainers = [
       rob
       bobvanderlinden

nixos/tests/transmission.nix

@@ -1,5 +1,5 @@
 import ./make-test-python.nix (
-  { pkgs, transmission, ... }:
+  { pkgs, ... }:
   {
     name = "transmission";
     meta = with pkgs.lib.maintainers; {
@@ -16,7 +16,6 @@ import ./make-test-python.nix (
         security.apparmor.enable = true;
 
         services.transmission.enable = true;
-        services.transmission.package = transmission;
       };
 
     testScript = ''

pkgs/build-support/fetchtorrent/default.nix

@@ -1,7 +1,7 @@
 {
   lib,
   runCommand,
-  transmission_3_noSystemd,
+  transmission_4,
   rqbit,
   writeShellScript,
   formats,
@@ -97,7 +97,7 @@ runCommand name
     ]
     ++ (
       if (backend == "transmission") then
-        [ transmission_3_noSystemd ]
+        [ transmission_4 ]
       else if (backend == "rqbit") then
         [ rqbit ]
       else
@@ -132,7 +132,6 @@ runCommand name
             --portmap \
             --finish ${transmissionFinishScript} \
             --download-dir "$downloadedDirectory" \
-            --config-dir "$HOME"/.config/transmission \
             "$url"
       ''
     else