diff --git a/src/game/project.godot b/src/game/project.godot
index e97ceb4e..9cad5e2a 100644
--- a/src/game/project.godot
+++ b/src/game/project.godot
@@ -28,6 +28,7 @@ StatsTracker="*res://engine/src/autoloads/stats_tracker.gd"
 TurnManager="*res://engine/src/autoloads/turn_manager.gd"
 ThroneRoomProfile="*res://engine/src/modules/empire/throne_room_profile.gd"
 SpriteManifest="*res://engine/src/autoloads/sprite_manifest.gd"
+ModLoader="*res://engine/src/autoloads/mod_loader.gd"
 ProceduralRenderer="*res://engine/src/world/procedural_renderer.gd"
 ScreenCapture="*res://engine/scenes/tests/capture_screenshot.gd"
 AutoPlay="*res://engine/scenes/tests/auto_play.gd"
diff --git a/tools/sign-mod.sh b/tools/sign-mod.sh
new file mode 100755
index 00000000..44c68022
--- /dev/null
+++ b/tools/sign-mod.sh
@@ -0,0 +1,64 @@
+#!/usr/bin/env bash
+# sign-mod.sh — produce the base64 ed25519 signature for a native AI-controller
+# mod payload, ready to drop into manifest.json#/signature.
+#
+# Usage:
+#   tools/sign-mod.sh <binary-path> <private-key-path>
+#
+# Where:
+#   <binary-path>      Path to controller.so / controller.dll / controller.dylib
+#   <private-key-path> PEM-encoded ed25519 private key. Generate one with:
+#                        openssl genpkey -algorithm ed25519 -out engine.key
+#                      and publish the matching public key:
+#                        openssl pkey -in engine.key -pubout -out engine.pub
+#
+# Output: 88-char base64 string (64 raw bytes) on stdout. Paste into the
+# mod's manifest.json #/signature field.
+#
+# Protocol (mirrors mc-mod-host/src/signing.rs):
+#   1. SHA-256 the binary bytes.
+#   2. Sign the 32-byte digest with the ed25519 private key.
+#   3. Base64-encode the 64-byte signature.
+#
+# The host re-computes the digest and verifies against the engine-release
+# public key embedded in ENGINE_PUBKEY (see signing.rs). Mods built
+# without access to the matching private key will not load.
+#
+# TRACKED: the engine release pubkey constant is currently zero-bytes,
+# so signatures produced here will NOT verify against the shipped
+# engine until the release pipeline (Stage 6) bakes in a real key.
+# See docs/modding/abi-decisions.md §"Native sandbox" for the deferral.
+
+set -euo pipefail
+
+if [[ $# -ne 2 ]]; then
+  echo "usage: $0 <binary-path> <private-key-path>" >&2
+  exit 64
+fi
+
+BIN="$1"
+KEY="$2"
+
+if [[ ! -f "$BIN" ]]; then
+  echo "error: binary not found: $BIN" >&2
+  exit 66
+fi
+if [[ ! -f "$KEY" ]]; then
+  echo "error: private key not found: $KEY" >&2
+  exit 66
+fi
+
+TMP_DIGEST="$(mktemp)"
+TMP_SIG="$(mktemp)"
+trap 'rm -f "$TMP_DIGEST" "$TMP_SIG"' EXIT
+
+# 1. SHA-256 the binary into raw 32 bytes.
+openssl dgst -sha256 -binary "$BIN" > "$TMP_DIGEST"
+
+# 2. Sign the digest with the ed25519 private key. `openssl pkeyutl` with
+#    an ed25519 key takes the message directly (no -digest flag).
+openssl pkeyutl -sign -inkey "$KEY" -rawin -in "$TMP_DIGEST" -out "$TMP_SIG"
+
+# 3. Base64-encode and emit on a single line.
+base64 -w 0 < "$TMP_SIG"
+echo