diff --git a/nix/checks.nix b/nix/checks.nix
index 8adb56628d2..2bd4f642bbd 100644
--- a/nix/checks.nix
+++ b/nix/checks.nix
@@ -240,6 +240,27 @@ json.dump(sorted(leaf_paths(DEFAULT_CONFIG)), sys.stdout, indent=2)
           echo "ok" > $out/result
         '';
 
+        # Verify extraDependencyGroups passes through to python.nix
+        extra-dependency-groups = let
+          hermesWithGroups = hermes-agent.override {
+            extraDependencyGroups = [ "honcho" ];
+          };
+        in pkgs.runCommand "hermes-extra-dependency-groups" { } ''
+          set -e
+          echo "=== Checking extraDependencyGroups override evaluates ==="
+
+          # Eval-only: verify the override produces valid derivation paths
+          # without building the full venv (which is expensive and redundant
+          # since the mechanism is just list concatenation into python.nix).
+          echo "derivation: ${hermesWithGroups}"
+          echo "venv: ${hermesWithGroups.hermesVenv}"
+          echo "PASS: extraDependencyGroups override evaluates cleanly"
+
+          echo "=== All extraDependencyGroups checks passed ==="
+          mkdir -p $out
+          echo "ok" > $out/result
+        '';
+
         # ── Config merge + round-trip test ────────────────────────────────
         # Tests the merge script (Nix activation behavior) across 7
         # scenarios, then verifies Python's load_config() reads correctly.
diff --git a/nix/hermes-agent.nix b/nix/hermes-agent.nix
index c3bde20c81c..ce8be16cfdd 100644
--- a/nix/hermes-agent.nix
+++ b/nix/hermes-agent.nix
@@ -1,7 +1,9 @@
 # nix/hermes-agent.nix — Overridable Hermes Agent package
 #
 # callPackage auto-wires nixpkgs args; flake inputs are passed explicitly.
-# Users override via: pkgs.hermes-agent.override { extraPythonPackages = [...]; }
+# Users override via:
+#   pkgs.hermes-agent.override { extraPythonPackages = [...]; }
+#   pkgs.hermes-agent.override { extraDependencyGroups = [ "hindsight" ]; }
 {
   lib,
   stdenv,
@@ -25,11 +27,13 @@
   rev ? null,
   # Overridable parameters
   extraPythonPackages ? [ ],
+  extraDependencyGroups ? [ ],
 }:
 let
   nodejs = nodejs_22;
   hermesVenv = callPackage ./python.nix {
     inherit uv2nix pyproject-nix pyproject-build-systems;
+    dependency-groups = [ "all" ] ++ extraDependencyGroups;
   };
 
   hermesNpmLib = callPackage ./lib.nix {
diff --git a/nix/nixosModules.nix b/nix/nixosModules.nix
index fbff28e18b6..475e5b5ba5a 100644
--- a/nix/nixosModules.nix
+++ b/nix/nixosModules.nix
@@ -28,8 +28,10 @@
 
   let
     cfg = config.services.hermes-agent;
-    effectivePackage = if cfg.extraPythonPackages == [ ] then cfg.package
-      else cfg.package.override { inherit (cfg) extraPythonPackages; };
+    effectivePackage =
+      if cfg.extraPythonPackages == [ ] && cfg.extraDependencyGroups == [ ]
+      then cfg.package
+      else cfg.package.override { inherit (cfg) extraPythonPackages extraDependencyGroups; };
     hermes-agent = inputs.self.packages.${pkgs.stdenv.hostPlatform.system}.default;
 
     # Deep-merge config type (from 0xrsydn/nix-hermes-agent)
@@ -512,6 +514,21 @@
         '';
       };
 
+      extraDependencyGroups = mkOption {
+        type = types.listOf types.str;
+        default = [ ];
+        description = ''
+          Additional pyproject.toml optional-dependency groups to include in
+          the sealed Python venv. These are resolved by uv alongside core
+          dependencies — no PYTHONPATH patching or collision risk.
+
+          Use this for optional extras already declared in hermes-agent's
+          pyproject.toml (e.g. "hindsight", "honcho", "voice").
+          Use extraPythonPackages for external packages not in pyproject.toml.
+        '';
+        example = [ "hindsight" ];
+      };
+
       restart = mkOption {
         type = types.str;
         default = "always";
diff --git a/website/docs/getting-started/nix-setup.md b/website/docs/getting-started/nix-setup.md
index d97961a93bd..80e8cae9746 100644
--- a/website/docs/getting-started/nix-setup.md
+++ b/website/docs/getting-started/nix-setup.md
@@ -645,6 +645,28 @@ services.hermes-agent.extraPythonPackages = [
 
 The package's `site-packages` is added to PYTHONPATH in the hermes wrapper. `importlib.metadata` discovers the entry point at session start.
 
+### Optional Dependency Groups (`extraDependencyGroups`)
+
+For optional extras already declared in hermes-agent's `pyproject.toml` (e.g., memory providers like `hindsight` or `honcho`), use `extraDependencyGroups` to include them in the sealed venv at build time:
+
+```nix
+services.hermes-agent = {
+  extraDependencyGroups = [ "hindsight" ];
+  settings.memory.provider = "hindsight";
+};
+```
+
+This is resolved by uv alongside core dependencies in a single pass — no PYTHONPATH patching, no collision risk. Available groups match the `[project.optional-dependencies]` keys in `pyproject.toml` (e.g., `"hindsight"`, `"honcho"`, `"voice"`, `"matrix"`, `"mistral"`, `"bedrock"`).
+
+**When to use which:**
+
+| Need | Option |
+|------|--------|
+| Enable a pyproject.toml optional extra | `extraDependencyGroups` |
+| Add an external Python plugin not in pyproject.toml | `extraPythonPackages` |
+| Add a system binary (pandoc, jq, etc.) | `extraPackages` |
+| Add a directory-based plugin source tree | `extraPlugins` |
+
 ### Combining Both
 
 A directory plugin with third-party Python dependencies needs both options:
@@ -666,7 +688,9 @@ External flakes can override the package directly:
   inputs.hermes-agent.url = "github:NousResearch/hermes-agent";
   outputs = { hermes-agent, nixpkgs, ... }: {
     nixpkgs.overlays = [ hermes-agent.overlays.default ];
-    # Then: pkgs.hermes-agent.override { extraPythonPackages = [...]; }
+    # Then:
+    #   pkgs.hermes-agent.override { extraPythonPackages = [...]; }
+    #   pkgs.hermes-agent.override { extraDependencyGroups = [ "hindsight" ]; }
   };
 }
 ```
@@ -812,6 +836,7 @@ nix build .#checks.x86_64-linux.config-roundtrip    # merge script preserves use
 | `extraPackages` | `listOf package` | `[]` | Extra packages available to the agent. Added to the hermes user's per-user profile so terminal commands, skills, and cron jobs all see them |
 | `extraPlugins` | `listOf package` | `[]` | Directory plugin packages to symlink into `$HERMES_HOME/plugins/`. Each must contain `plugin.yaml` |
 | `extraPythonPackages` | `listOf package` | `[]` | Python packages added to PYTHONPATH for entry-point plugin discovery. Build with `python312Packages` |
+| `extraDependencyGroups` | `listOf str` | `[]` | pyproject.toml optional extras to include in the sealed venv (e.g. `["hindsight"]`). Resolved by uv — no collisions |
 | `restart` | `str` | `"always"` | systemd `Restart=` policy |
 | `restartSec` | `int` | `5` | systemd `RestartSec=` value |