diff --git a/.config/filegen-manifest.json b/.config/filegen-manifest.json
deleted file mode 100644
index 715da83..0000000
--- a/.config/filegen-manifest.json
+++ /dev/null
@@ -1,33 +0,0 @@
-{
-  "clobber-by-default": true,
-  "files": [
-    {
-      "clobber": null,
-      "deactivate": null,
-      "ignore-modification": null,
-      "permissions": "600",
-      "source": "/nix/store/i9wgm4ljangrsv39rjdqyq9j96hj29zm-pre-commit-config.yaml",
-      "target": "./.pre-commit-config.yaml",
-      "type": "copy"
-    },
-    {
-      "clobber": null,
-      "deactivate": null,
-      "ignore-modification": null,
-      "permissions": "600",
-      "source": "/nix/store/wyggpw11mkdvbcgbqzs80py8z8khjk9i-check-pre-commit-hooks.yml",
-      "target": "./.github/workflows/check-pre-commit-hooks.yml",
-      "type": "copy"
-    },
-    {
-      "clobber": null,
-      "deactivate": null,
-      "ignore-modification": null,
-      "permissions": "600",
-      "source": "/nix/store/mv9zlzz043051izx92fxk6ibz6fn21yd-gitattributes",
-      "target": ".gitattributes",
-      "type": "copy"
-    }
-  ],
-  "version": 3
-}
diff --git a/.gitattributes b/.gitattributes
index 5daa663..f2ec25b 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -1,4 +1,3 @@
 .pre-commit-config.yaml linguist-generated
 .github/workflows/check-pre-commit-hooks.yml linguist-generated
 .gitattributes linguist-generated
-.config/filegen-manifest.json linguist-generated
diff --git a/.gitignore b/.gitignore
index f418f1a..42e9235 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,5 @@
 .devenv/
+
+# filegen activation state — contains machine-specific /nix/store source
+# paths, so it must not be committed (would cause cross-system drift).
+.config/filegen-manifest.json
diff --git a/nix/modules/filegen.nix b/nix/modules/filegen.nix
index 0e43339..e1a2b7b 100644
--- a/nix/modules/filegen.nix
+++ b/nix/modules/filegen.nix
@@ -169,6 +169,9 @@ in
     { pkgs, config, ... }:
     let
       cfg = config.filegen;
+      # The manifest records absolute /nix/store source paths, which differ
+      # per system. It is therefore local activation state (gitignored), not a
+      # committed artifact — committing it would cause cross-system drift.
       new-manifest = pkgs.writers.writeJSON "filegen-manifest.json" (
         config.filegen.settings // { inherit (smfh) version; }
       );
@@ -185,7 +188,7 @@ in
           target = ".gitattributes";
           source = pkgs.writeTextFile {
             name = ".gitattributes";
-            text = lib.pipe (cfg.settings.files ++ [ { target = ".config/filegen-manifest.json"; } ]) [
+            text = lib.pipe cfg.settings.files [
               (map (file: lib.removePrefix "./" file.target))
               (map (target: "${target} linguist-generated"))
               lib.concatLines