diff --git a/.gitignore b/.gitignore
index 69ae774..bae95d7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,6 +7,9 @@ packages/bin/kitchen
 result
 result-*
 
+# test coverage output
+coverage/
+
 # direnv / nix-direnv cache
 .direnv/
 
diff --git a/bunfig.toml b/bunfig.toml
new file mode 100644
index 0000000..4c20355
--- /dev/null
+++ b/bunfig.toml
@@ -0,0 +1,8 @@
+[test]
+# Coverage is opt-in via `bun test --coverage` (see the test:coverage script).
+# These settings only take effect when that flag is passed.
+coverageReporter = ["text", "lcov"]
+coverageDir = "coverage"
+coverageSkipTestFiles = true
+# test-support.ts is test scaffolding, not product code; keep it out of the numbers.
+coveragePathIgnorePatterns = ["**/test-support.ts"]
diff --git a/package.json b/package.json
index af0041e..fcd48b1 100644
--- a/package.json
+++ b/package.json
@@ -8,6 +8,7 @@
   ],
   "scripts": {
     "test": "bun test",
+    "test:coverage": "bun test --coverage",
     "lint": "biome check .",
     "format": "biome check --write .",
     "postinstall": "bun2nix -o bun.nix"