diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 8a4d0d05e..ba95fa133 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -18,12 +18,15 @@ git clone https://github.com/databuddy-analytics/Databuddy.git
 cd databuddy
 ```
 
-2. Install dependencies:
+2. Install dependencies (requires Bun ≥ 1.2.0 — run `bun --version` to check, upgrade at https://bun.sh if needed):
 
 ```bash
 bun install
 ```
 
+> [!NOTE]
+> Bun ≥ 1.2.0 is only the minimum required for `catalog:` protocol support. The repo pins an exact version via the `packageManager` field in `package.json`, so contributors should use that version to avoid install conflicts (check it with `grep packageManager package.json`, or activate it via Corepack with `corepack prepare bun@<version> --activate`).
+
 3. Set up environment variables:
 
 ```bash
diff --git a/package.json b/package.json
index 85a9b6f52..c09d8b93f 100644
--- a/package.json
+++ b/package.json
@@ -24,7 +24,8 @@
     "ultracite": "^7.6.1"
   },
   "engines": {
-    "node": ">=20"
+    "node": ">=20",
+    "bun": ">=1.2.0"
   },
   "overrides": {
     "protobufjs": ">=7.5.5",