3 files changed, 30 insertions, 0 deletions
diff --git a/nix/overlay/development.nix b/nix/overlay/development.nix
index b414597..c956556 100644
--- a/nix/overlay/development.nix
+++ b/nix/overlay/development.nix
@@ -7,6 +7,8 @@ final: prev: {
       final': prev': {
          dev-shell = final'.callPackage ../package/dev-shell.nix { };
 
+         mark-darcs-weak-hash = final'.callPackage ../package/mark-darcs-weak-hash.nix { };
+
          nixfmt-3-space = final'.callPackage ../package/nixfmt-3-space.nix { };
 
          ocamlformat-rpc-bin = final'.callPackage ../package/ocamlformat-rpc-bin.nix { };
diff --git a/nix/package/dev-shell.nix b/nix/package/dev-shell.nix
index 77a9ac1..3cfec5c 100644
--- a/nix/package/dev-shell.nix
+++ b/nix/package/dev-shell.nix
@@ -7,6 +7,7 @@
    kdlfmt,
    topiary,
    ocamlPackages,
+   mark-darcs-weak-hash,
    nixtamal,
    nixfmt-3-space,
    ocamlformat-rpc-bin,
@@ -19,6 +20,7 @@ mkShell {
    ];
    packages = [
       kdlfmt
+      mark-darcs-weak-hash
       nixfmt-3-space
       topiary
 
diff --git a/nix/package/mark-darcs-weak-hash.nix b/nix/package/mark-darcs-weak-hash.nix
new file mode 100644
index 0000000..7f644e1
--- /dev/null
+++ b/nix/package/mark-darcs-weak-hash.nix
@@ -0,0 +1,26 @@
+#──────────────────────────────────────────────────────────────────────────────┐
+# SPDX-FileCopyrightText: 2025 toastal <https://toast.al/contact/>             │
+# SPDX-License-Identifier: LGPL-2.1-or-later                                   │
+#──────────────────────────────────────────────────────────────────────────────┘
+{
+   lib,
+   writeDashBinScript,
+   darcs,
+   gawk,
+}:
+
+let
+   path = lib.makeBinPath [
+      darcs
+      gawk
+   ];
+in
+writeDashBinScript {
+   name = "mark-darcs-weak-hash";
+   text = /* sh */ ''
+      export PATH="${path}:$PATH"
+
+      darcs show repo \
+         | awk '/^[[:space:]]*Weak Hash:/ { sub(/^[[:space:]]*Weak Hash:[[:space:]]*/, "", $0); printf $0 }' > "$PWD/_darcs/weak_hash"
+   '';
+}