fix(nix): upgrade Python 3.11 → 3.12, add cross-platform eval check (#12208)

nix/checks.nix

@@ -37,7 +37,30 @@ json.dump(sorted(leaf_paths(DEFAULT_CONFIG)), sys.stdout, indent=2)
     in {
       packages.configKeys = configKeys;
 
-      checks = lib.optionalAttrs pkgs.stdenv.hostPlatform.isLinux {
+      checks = {
+        # Cross-platform evaluation — catches "not supported for interpreter"
+        # errors (e.g. sphinx dropping python311) without needing a darwin builder.
+        # Evaluation is pure and instant; it doesn't build anything.
+        cross-eval = let
+          targetSystems = builtins.filter
+            (s: inputs.self.packages ? ${s})
+            [ "x86_64-linux" "aarch64-linux" "aarch64-darwin" "x86_64-darwin" ];
+          tryEvalPkg = sys:
+            let pkg = inputs.self.packages.${sys}.default;
+            in builtins.tryEval (builtins.seq pkg.drvPath true);
+          results = map (sys: { inherit sys; result = tryEvalPkg sys; }) targetSystems;
+          failures = builtins.filter (r: !r.result.success) results;
+          failMsg = lib.concatMapStringsSep "\n" (r: "  - ${r.sys}") failures;
+        in pkgs.runCommand "hermes-cross-eval" { } (
+          if failures != [] then
+            builtins.throw "Package fails to evaluate on:\n${failMsg}"
+          else ''
+            echo "PASS: package evaluates on all ${toString (builtins.length targetSystems)} platforms"
+            mkdir -p $out
+            echo "ok" > $out/result
+          ''
+        );
+      } // lib.optionalAttrs pkgs.stdenv.hostPlatform.isLinux {
         # Verify binaries exist and are executable
         package-contents = pkgs.runCommand "hermes-package-contents" { } ''
           set -e

nix/devShell.nix

@@ -12,7 +12,7 @@
       devShells.default = pkgs.mkShell {
         inputsFrom = packages;
         packages = with pkgs; [
-          python311 uv nodejs_22 ripgrep git openssh ffmpeg
+          python312 uv nodejs_22 ripgrep git openssh ffmpeg
         ];
 
         shellHook = let

nix/nixosModules.nix

@@ -148,15 +148,14 @@
         su -s /bin/sh "$TARGET_USER" -c 'curl -LsSf https://astral.sh/uv/install.sh | sh' || true
       fi
 
-      # Python 3.11 venv — gives the agent a writable Python with pip.
-      # Uses uv to install Python 3.11 (Ubuntu 24.04 ships 3.12).
+      # Python 3.12 venv — gives the agent a writable Python with pip.
       # --seed includes pip/setuptools so bare `pip install` works.
       _UV_BIN="$TARGET_HOME/.local/bin/uv"
       if [ ! -d "$TARGET_HOME/.venv" ] && [ -x "$_UV_BIN" ]; then
         su -s /bin/sh "$TARGET_USER" -c "
           export PATH=\"\$HOME/.local/bin:\$PATH\"
-          uv python install 3.11
-          uv venv --python 3.11 --seed \"\$HOME/.venv\"
+          uv python install 3.12
+          uv venv --python 3.12 --seed \"\$HOME/.venv\"
         " || true
       fi
 

nix/packages.nix

@@ -87,7 +87,7 @@
             STAMP_VALUE="${pyprojectHash}:${uvLockHash}"
             if [ ! -f "$STAMP" ] || [ "$(cat "$STAMP")" != "$STAMP_VALUE" ]; then
               echo "hermes-agent: installing Python dependencies..."
-              uv venv .venv --python ${pkgs.python311}/bin/python3 2>/dev/null || true
+              uv venv .venv --python ${pkgs.python312}/bin/python3 2>/dev/null || true
               source .venv/bin/activate
               uv pip install -e ".[all]"
               [ -d mini-swe-agent ] && uv pip install -e ./mini-swe-agent 2>/dev/null || true

nix/python.nix

@@ -1,6 +1,6 @@
 # nix/python.nix — uv2nix virtual environment builder
 {
-  python311,
+  python312,
   lib,
   callPackage,
   uv2nix,
@@ -51,28 +51,30 @@ let
 
   pythonPackageOverrides = final: _prev:
     if isAarch64Darwin then {
-      numpy = mkPrebuiltOverride final python311.pkgs.numpy { };
+      numpy = mkPrebuiltOverride final python312.pkgs.numpy { };
 
-      av = mkPrebuiltOverride final python311.pkgs.av { };
+      pyarrow = mkPrebuiltOverride final python312.pkgs.pyarrow { };
 
-      humanfriendly = mkPrebuiltOverride final python311.pkgs.humanfriendly { };
+      av = mkPrebuiltOverride final python312.pkgs.av { };
 
-      coloredlogs = mkPrebuiltOverride final python311.pkgs.coloredlogs {
+      humanfriendly = mkPrebuiltOverride final python312.pkgs.humanfriendly { };
+
+      coloredlogs = mkPrebuiltOverride final python312.pkgs.coloredlogs {
         humanfriendly = [ ];
       };
 
-      onnxruntime = mkPrebuiltOverride final python311.pkgs.onnxruntime {
+      onnxruntime = mkPrebuiltOverride final python312.pkgs.onnxruntime {
         coloredlogs = [ ];
         numpy = [ ];
         packaging = [ ];
       };
 
-      ctranslate2 = mkPrebuiltOverride final python311.pkgs.ctranslate2 {
+      ctranslate2 = mkPrebuiltOverride final python312.pkgs.ctranslate2 {
         numpy = [ ];
         pyyaml = [ ];
       };
 
-      faster-whisper = mkPrebuiltOverride final python311.pkgs.faster-whisper {
+      faster-whisper = mkPrebuiltOverride final python312.pkgs.faster-whisper {
         av = [ ];
         ctranslate2 = [ ];
         huggingface-hub = [ ];
@@ -84,7 +86,7 @@ let
 
   pythonSet =
     (callPackage pyproject-nix.build.packages {
-      python = python311;
+      python = python312;
     }).overrideScope
       (lib.composeManyExtensions [
         pyproject-build-systems.overlays.default