diff --git a/modules/features/git.nix b/modules/features/git.nix
index 31f95e3..f97aac7 100644
--- a/modules/features/git.nix
+++ b/modules/features/git.nix
@@ -9,6 +9,7 @@
     let
       user = config.meta.user;
       primaryEmail = builtins.head (lib.filter (email: email.primary) (builtins.attrValues user.emails));
+      usesScopedIdentity = user != null && user.sourceControl.profiles != { };
     in
     {
       programs.git = {
@@ -20,6 +21,8 @@
         ];
         settings = {
           init.defaultBranch = "main";
+        }
+        // lib.optionalAttrs (!usesScopedIdentity) {
           user = {
             name = user.realName;
             email = primaryEmail.address;
diff --git a/modules/features/meta.nix b/modules/features/meta.nix
index c6d7228..4488b2b 100644
--- a/modules/features/meta.nix
+++ b/modules/features/meta.nix
@@ -26,6 +26,69 @@ let
     }
   );
 
+  sourceControlHostKeyType = lib.types.submodule (
+    { ... }:
+    {
+      options = {
+        publicKey = lib.mkOption {
+          type = lib.types.str;
+        };
+
+        privateKeyPath = lib.mkOption {
+          type = lib.types.nullOr lib.types.str;
+          default = null;
+        };
+      };
+    }
+  );
+
+  sourceControlHostUserType = lib.types.submodule (
+    { ... }:
+    {
+      options = {
+        personal = mkNullableOption sourceControlHostKeyType;
+        work = mkNullableOption sourceControlHostKeyType;
+      };
+    }
+  );
+
+  hostSourceControlType = lib.types.submodule (
+    { ... }:
+    {
+      options.users = lib.mkOption {
+        type = lib.types.attrsOf sourceControlHostUserType;
+        default = { };
+      };
+    }
+  );
+
+  sourceControlProfileType = lib.types.submodule (
+    { ... }:
+    {
+      options = { };
+    }
+  );
+
+  sourceControlType = lib.types.submodule (
+    { ... }:
+    {
+      options = {
+        profiles = lib.mkOption {
+          type = lib.types.attrsOf sourceControlProfileType;
+          default = { };
+        };
+
+        projectScope = lib.mkOption {
+          type = lib.types.enum [
+            "personal"
+            "work"
+          ];
+          default = "personal";
+        };
+      };
+    }
+  );
+
   userType = lib.types.submodule (
     { config, ... }:
     {
@@ -54,6 +117,11 @@ let
         emails = lib.mkOption {
           type = lib.types.attrsOf emailType;
         };
+
+        sourceControl = lib.mkOption {
+          type = sourceControlType;
+          default = { };
+        };
       };
     }
   );
@@ -111,20 +179,28 @@ let
     { ... }:
     {
       options = {
-        accelProfile = mkNullableOption (lib.types.nullOr (lib.types.enum [
-          "adaptive"
-          "flat"
-        ]));
+        accelProfile = mkNullableOption (
+          lib.types.nullOr (
+            lib.types.enum [
+              "adaptive"
+              "flat"
+            ]
+          )
+        );
         accelSpeed = mkNullableOption (lib.types.nullOr lib.types.float);
         leftHanded = mkNullableOption (lib.types.nullOr lib.types.bool);
         middleEmulation = mkNullableOption (lib.types.nullOr lib.types.bool);
         naturalScrolling = mkNullableOption (lib.types.nullOr lib.types.bool);
-        scrollMethod = mkNullableOption (lib.types.nullOr (lib.types.enum [
-          "no-scroll"
-          "two-finger"
-          "edge"
-          "on-button-down"
-        ]));
+        scrollMethod = mkNullableOption (
+          lib.types.nullOr (
+            lib.types.enum [
+              "no-scroll"
+              "two-finger"
+              "edge"
+              "on-button-down"
+            ]
+          )
+        );
       };
     }
   );
@@ -133,25 +209,37 @@ let
     { ... }:
     {
       options = {
-        accelProfile = mkNullableOption (lib.types.nullOr (lib.types.enum [
-          "adaptive"
-          "flat"
-        ]));
+        accelProfile = mkNullableOption (
+          lib.types.nullOr (
+            lib.types.enum [
+              "adaptive"
+              "flat"
+            ]
+          )
+        );
         accelSpeed = mkNullableOption (lib.types.nullOr lib.types.float);
-        clickMethod = mkNullableOption (lib.types.nullOr (lib.types.enum [
-          "button-areas"
-          "clickfinger"
-        ]));
+        clickMethod = mkNullableOption (
+          lib.types.nullOr (
+            lib.types.enum [
+              "button-areas"
+              "clickfinger"
+            ]
+          )
+        );
         disableWhileTyping = mkNullableOption (lib.types.nullOr lib.types.bool);
         leftHanded = mkNullableOption (lib.types.nullOr lib.types.bool);
         middleEmulation = mkNullableOption (lib.types.nullOr lib.types.bool);
         naturalScrolling = mkNullableOption (lib.types.nullOr lib.types.bool);
-        scrollMethod = mkNullableOption (lib.types.nullOr (lib.types.enum [
-          "no-scroll"
-          "two-finger"
-          "edge"
-          "on-button-down"
-        ]));
+        scrollMethod = mkNullableOption (
+          lib.types.nullOr (
+            lib.types.enum [
+              "no-scroll"
+              "two-finger"
+              "edge"
+              "on-button-down"
+            ]
+          )
+        );
         tapping = mkNullableOption (lib.types.nullOr lib.types.bool);
       };
     }
@@ -196,6 +284,11 @@ let
           type = lib.types.attrsOf userType;
           default = { };
         };
+
+        sourceControl = lib.mkOption {
+          type = hostSourceControlType;
+          default = { };
+        };
       };
     }
   );
diff --git a/modules/features/source-control.nix b/modules/features/source-control.nix
new file mode 100644
index 0000000..46c032c
--- /dev/null
+++ b/modules/features/source-control.nix
@@ -0,0 +1,160 @@
+{ config, lib, ... }:
+let
+  homeModules = config.flake.modules.homeManager;
+  serviceHostNames = {
+    github = "github.com";
+    gitlab = "gitlab.com";
+  };
+in
+{
+  flake.modules.homeManager.source-control =
+    {
+      config,
+      lib,
+      ...
+    }:
+    let
+      host = config.meta.host;
+      user = config.meta.user;
+      sourceControl = user.sourceControl;
+      hostSourceControlUsers = host.sourceControl.users;
+      hostUserSourceControl =
+        if lib.hasAttr user.name hostSourceControlUsers then hostSourceControlUsers.${user.name} else { };
+      profileNames = builtins.attrNames sourceControl.profiles;
+
+      parsedProfiles = map (
+        name:
+        let
+          matches = builtins.match "(github|gitlab)-(personal|work)" name;
+        in
+        {
+          inherit matches name;
+          isValid = matches != null;
+          scope = if matches == null then null else builtins.elemAt matches 1;
+          service = if matches == null then null else builtins.elemAt matches 0;
+        }
+      ) profileNames;
+
+      validProfiles = builtins.filter (profile: profile.isValid) parsedProfiles;
+      invalidProfileNames = map (profile: profile.name) (
+        builtins.filter (profile: !profile.isValid) parsedProfiles
+      );
+
+      emailNamesForScope = {
+        personal = [
+          "personal"
+          "main"
+        ];
+        work = [ "work" ];
+      };
+
+      scopeEmails =
+        scope:
+        map (name: user.emails.${name}) (
+          builtins.filter (name: lib.hasAttr name user.emails) emailNamesForScope.${scope}
+        );
+
+      emailForScope =
+        scope:
+        let
+          emails = scopeEmails scope;
+        in
+        if builtins.length emails == 1 then (builtins.head emails).address else null;
+
+      scopeConfig =
+        scope: if lib.hasAttr scope hostUserSourceControl then hostUserSourceControl.${scope} else null;
+
+      privateKeyPathForScope =
+        scope:
+        let
+          keyConfig = scopeConfig scope;
+        in
+        if keyConfig == null || keyConfig.privateKeyPath == null then
+          "~/.ssh/id_${scope}"
+        else
+          keyConfig.privateKeyPath;
+
+      scopePublicKey =
+        scope:
+        let
+          keyConfig = scopeConfig scope;
+        in
+        if keyConfig == null then null else keyConfig.publicKey;
+
+      scopesInUse = lib.unique (
+        [
+          "personal"
+          sourceControl.projectScope
+        ]
+        ++ map (profile: profile.scope) validProfiles
+      );
+
+      missingKeyScopes = builtins.filter (scope: scopePublicKey scope == null) scopesInUse;
+      invalidEmailScopes = builtins.filter (scope: emailForScope scope == null) scopesInUse;
+      allowedSignersLines = map (scope: "${emailForScope scope} ${scopePublicKey scope}") (
+        builtins.filter (scope: emailForScope scope != null && scopePublicKey scope != null) scopesInUse
+      );
+
+      gitConfigForScope = scope: {
+        gpg.ssh.allowedSignersFile = "${config.xdg.configHome}/git/allowed_signers";
+        user = {
+          name = user.realName;
+          email = emailForScope scope;
+          signingKey = "${privateKeyPathForScope scope}.pub";
+        };
+      };
+
+      gitRoots = [
+        {
+          root = user.nixosConfigurationPath;
+          scope = "personal";
+        }
+        {
+          root = config.xdg.userDirs.projects;
+          scope = sourceControl.projectScope;
+        }
+      ];
+    in
+    {
+      imports = [ homeModules.git ];
+
+      assertions = [
+        {
+          assertion = invalidProfileNames == [ ];
+          message = "Invalid source control profiles for `${user.name}`: ${lib.concatStringsSep ", " invalidProfileNames}. Expected `<service>-<scope>` using github/gitlab and personal/work.";
+        }
+        {
+          assertion = missingKeyScopes == [ ];
+          message = "Missing source control keys for `${user.name}` scopes: ${lib.concatStringsSep ", " missingKeyScopes}.";
+        }
+        {
+          assertion = invalidEmailScopes == [ ];
+          message = "Expected exactly one email selected by name for `${user.name}` scopes: ${lib.concatStringsSep ", " invalidEmailScopes}. Personal uses `personal` or `main`; work uses `work`.";
+        }
+      ];
+
+      xdg.configFile."git/allowed_signers".text = lib.concatStringsSep "\n" (
+        allowedSignersLines ++ [ "" ]
+      );
+
+      programs.git.includes = map (gitRoot: {
+        condition = "gitdir:${gitRoot.root}/";
+        contents = gitConfigForScope gitRoot.scope;
+      }) gitRoots;
+
+      programs.ssh = {
+        enable = true;
+        matchBlocks = lib.listToAttrs (
+          map (
+            profile:
+            lib.nameValuePair profile.name {
+              hostname = serviceHostNames.${profile.service};
+              identitiesOnly = true;
+              identityFile = privateKeyPathForScope profile.scope;
+              user = "git";
+            }
+          ) validProfiles
+        );
+      };
+    };
+}
diff --git a/modules/features/terminal.nix b/modules/features/terminal.nix
index 62b90a4..f8a4bb9 100644
--- a/modules/features/terminal.nix
+++ b/modules/features/terminal.nix
@@ -17,8 +17,7 @@ in
       };
       hasTerminalPackage = terminalPackage != null;
       hasMainProgram = hasTerminalPackage && terminalPackage ? meta.mainProgram;
-      terminalDesktopId =
-        if hasMainProgram then "${terminalPackage.meta.mainProgram}.desktop" else null;
+      terminalDesktopId = if hasMainProgram then "${terminalPackage.meta.mainProgram}.desktop" else null;
     in
     {
       assertions = [
@@ -31,7 +30,8 @@ in
           message = "Terminal package `${lib.showAttrPath config.meta.user.terminalPackagePath}` must define `meta.mainProgram`.";
         }
         {
-          assertion = hasMainProgram && builtins.pathExists "${terminalPackage}/share/applications/${terminalDesktopId}";
+          assertion =
+            hasMainProgram && builtins.pathExists "${terminalPackage}/share/applications/${terminalDesktopId}";
           message = "Terminal package `${lib.showAttrPath config.meta.user.terminalPackagePath}` must provide `${terminalDesktopId}`.";
         }
         {
diff --git a/modules/features/workstation-base.nix b/modules/features/workstation-base.nix
index f80f115..7420d4d 100644
--- a/modules/features/workstation-base.nix
+++ b/modules/features/workstation-base.nix
@@ -35,7 +35,6 @@ in
       homeModules.ai
       homeModules.clipboard
       homeModules.dev-tools
-      homeModules.git
       homeModules.local-apps
       homeModules.mpv
       homeModules.neovim
@@ -46,6 +45,7 @@ in
       homeModules.podman
       homeModules.shell
       homeModules.sops
+      homeModules.source-control
       homeModules.ssh-client
       homeModules.terminal
       homeModules.theme
diff --git a/modules/hosts/orion/default.nix b/modules/hosts/orion/default.nix
index 92fea6e..e8bc5f1 100644
--- a/modules/hosts/orion/default.nix
+++ b/modules/hosts/orion/default.nix
@@ -42,7 +42,8 @@ in
       };
 
       environment.systemPackages = [
-      ] ++ lib.optional (terminalPackage != null && lib.elem "terminfo" terminalPackage.outputs) (
+      ]
+      ++ lib.optional (terminalPackage != null && lib.elem "terminfo" terminalPackage.outputs) (
         lib.getOutput "terminfo" terminalPackage
       );
     };
diff --git a/modules/hosts/polaris/default.nix b/modules/hosts/polaris/default.nix
index ed135f8..7b7acd1 100644
--- a/modules/hosts/polaris/default.nix
+++ b/modules/hosts/polaris/default.nix
@@ -29,6 +29,15 @@ in
       mouse.accelSpeed = 0.4;
     };
 
+    sourceControl.users = {
+      kiri.personal.publicKey = "";
+
+      ergon = {
+        personal.publicKey = "";
+        work.publicKey = "";
+      };
+    };
+
     users = {
       inherit (metaLib.users)
         ergon
diff --git a/modules/hosts/zenith/default.nix b/modules/hosts/zenith/default.nix
index 06e2cd5..2f9b692 100644
--- a/modules/hosts/zenith/default.nix
+++ b/modules/hosts/zenith/default.nix
@@ -30,6 +30,15 @@ in
       mouse.accelSpeed = 0.4;
     };
 
+    sourceControl.users = {
+      kiri.personal.publicKey = "";
+
+      ergon = {
+        personal.publicKey = "";
+        work.publicKey = "";
+      };
+    };
+
     users = {
       inherit (metaLib.users)
         ergon
diff --git a/modules/lib.nix b/modules/lib.nix
index 21fbb33..9db522d 100644
--- a/modules/lib.nix
+++ b/modules/lib.nix
@@ -9,6 +9,7 @@ let
       name,
       displays ? { },
       input ? { },
+      sourceControl ? { },
       users ? { },
       imports ? [ ],
       stateVersion ? "24.05",
@@ -19,6 +20,7 @@ let
           displays
           input
           name
+          sourceControl
           users
           ;
       };
diff --git a/modules/users.nix b/modules/users.nix
index 0f2c495..46741fa 100644
--- a/modules/users.nix
+++ b/modules/users.nix
@@ -6,7 +6,7 @@ let
     homeDirectory = "/home/kiri";
     terminalPackagePath = [ "kitty" ];
     emails = {
-      main = {
+      personal = {
         address = "mail@jelles.net";
         primary = true;
         type = "mxrouting";
@@ -27,6 +27,12 @@ let
         type = "office365";
       };
     };
+    sourceControl = {
+      profiles = {
+        github-personal = { };
+        gitlab-personal = { };
+      };
+    };
   };
 
   ergon = {
@@ -35,12 +41,26 @@ let
     homeDirectory = "/home/ergon";
     terminalPackagePath = [ "kitty" ];
     emails = {
+      personal = {
+        address = "mail@jelles.net";
+        primary = false;
+        type = "mxrouting";
+      };
       work = {
         address = "jelle.spreeuwenberg@yookr.org";
         primary = true;
         type = "office365";
       };
     };
+    sourceControl = {
+      profiles = {
+        github-personal = { };
+        github-work = { };
+        gitlab-personal = { };
+      };
+
+      projectScope = "work";
+    };
   };
 in
 {