feat(coding): enhance git, difftastic, and jj configuration

- Git: set main as default branch, configure difftastic as external diff
- Git: add useful aliases (co, br, lg, dft, ds, dl)
- Git: enable rerere, zdiff3 conflicts, merge-based pulls
- Difftastic: configure dark theme, Nix language support
- JJ: use difftastic as diff formatter with color support

profiles/sets/coding/core/git.nix

@@ -15,16 +15,79 @@ with lib; {
         email = lib.mkDefault "p@m3ta.dev";
       };
       core.excludesfile = "~/.gitignore_global";
-      init.defaultBranch = "master";
+      init.defaultBranch = "main";
+
+      # --- Diff-Config ---
+      # Use difftastic as default external diff tool
+      diff.external = "difft";
+      diff.colorMoved = "default";
+
+      # --- Merge-Config ---
+      merge.conflictStyle = "zdiff3";
+
+      # --- Pull-Config ---
+      # Use merge instead of rebase for clearer history
+      pull.rebase = false;
+
+      # --- Rerere ---
+      # Reuse recorded resolutions for recurring conflicts
+      rerere.enabled = true;
+
+      # --- Push-Config ---
+      # Automatically set upstream when pushing to new branch
+      push.autoSetupRemote = true;
+
+      # --- Pager ---
+      pager.diff = true;
+      pager.log = false;
+
+      # --- Aliases ---
       alias = {
+        # Basic shortcuts
         st = "status";
-        logd = "log --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset' --abbrev-commit";
+        co = "checkout";
+        br = "branch";
+
+        # Enhanced log with graph
+        lg = "log --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset' --abbrev-commit";
+
+        # Difftastic aliases for one-off usage
+        # Use with: git dft, git ds, git dl
+        dft = "-c diff.external=difft diff";
+        ds = "-c diff.external=difft show --ext-diff";
+        dl = "-c diff.external=difft log -p --ext-diff";
       };
     };
   };
 
-  programs.difftastic.enable = true;
+  # Difftastic configuration
+  programs.difftastic = {
+    enable = true;
+    options = {
+      # Anzeige: Passt zu den meisten Terminal-Themes
+      color = "dark";
 
+      # Word-level diffs inline statt side-by-side
+      side-by-side = false;
+
+      # Standard-Tab-Breite
+      tab-width = 8;
+
+      # Trailing Commas anzeigen
+      trailing-commas = true;
+
+      # Konsistente Diffs durch alphabetische Pfad-Sortierung
+      sort-paths = true;
+
+      # Nix-spezifisch
+      language = [
+        "Nix"
+        "Nanorc"
+      ];
+    };
+  };
+
+  # Jujutsu (jj) configuration
   programs.jujutsu = {
     enable = true;
     settings = {
@@ -32,6 +95,30 @@ with lib; {
         email = "m@m3tam3re.com";
         name = "Sascha Koenig";
       };
+
+      # --- UI ---
+      ui = {
+        # Immer Farben (auch in Pipes)
+        color = "always";
+
+        # Log als Default-Command
+        default-command = "log";
+
+        # Schönerer Graph
+        graph-style = "curved";
+
+        # Pager-Config
+        pager = "less -FRX";
+        paginate = "auto";
+
+        # --- Diff ---
+        # Difftastic als Default-Diff-Formatter
+        diff-formatter = ["difft" "--color=always" "$left" "$right"];
+      };
+
+      # --- Revsets ---
+      # Zeige @, Parent-Änderungen und immutable Heads
+      revsets.log = "present(@) | @-:: | immutable_heads()..";
     };
   };