From e5a5a75938098704340f8ced7e4aaa728eca82eb Mon Sep 17 00:00:00 2001
From: Tom Boucher <trekkie@nomorestars.com>
Date: Tue, 26 May 2026 12:22:02 -0400
Subject: [PATCH] fix(#321): replace JSON config default clone with
 structuredClone (#324)

---
 .changeset/eager-elks-romp.md                 |  5 ++++
 get-shit-done/bin/lib/configuration.cjs       |  2 +-
 ...21-config-defaults-clone-strategy.test.cjs | 23 +++++++++++++++++++
 3 files changed, 29 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/eager-elks-romp.md
 create mode 100644 tests/bug-321-config-defaults-clone-strategy.test.cjs

diff --git a/.changeset/eager-elks-romp.md b/.changeset/eager-elks-romp.md
new file mode 100644
index 000000000..aaa671249
--- /dev/null
+++ b/.changeset/eager-elks-romp.md
@@ -0,0 +1,5 @@
+---
+type: Fixed
+pr: 321
+---
+**`loadConfig` now clones config defaults with `structuredClone`** — avoids JSON round-trip fragility in defaults merging used by config loads and related tooling.
diff --git a/get-shit-done/bin/lib/configuration.cjs b/get-shit-done/bin/lib/configuration.cjs
index e6a2bcea0..19b730e41 100644
--- a/get-shit-done/bin/lib/configuration.cjs
+++ b/get-shit-done/bin/lib/configuration.cjs
@@ -158,7 +158,7 @@ function normalizeLegacyKeys(parsed) {
 
 function mergeDefaults(parsed) {
     // Start with a deep clone of defaults, then overlay parsed
-    const defaults = JSON.parse(JSON.stringify(CONFIG_DEFAULTS));
+    const defaults = structuredClone(CONFIG_DEFAULTS);
     return deepMergeConfig(defaults, parsed);
 }
 
diff --git a/tests/bug-321-config-defaults-clone-strategy.test.cjs b/tests/bug-321-config-defaults-clone-strategy.test.cjs
new file mode 100644
index 000000000..d0d35bc30
--- /dev/null
+++ b/tests/bug-321-config-defaults-clone-strategy.test.cjs
@@ -0,0 +1,23 @@
+'use strict';
+
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const configuration = require('../get-shit-done/bin/lib/configuration.cjs');
+
+test('mergeDefaults clones defaults without JSON serialization fragility (#321)', () => {
+  const sentinelKey = '__bug321_bigint_sentinel__';
+  const sentinelValue = BigInt('9007199254740993001');
+
+  configuration.CONFIG_DEFAULTS[sentinelKey] = sentinelValue;
+  try {
+    const merged = configuration.mergeDefaults({});
+    assert.equal(
+      merged[sentinelKey],
+      sentinelValue,
+      'mergeDefaults must preserve non-JSON scalar defaults when cloning'
+    );
+  }
+  finally {
+    delete configuration.CONFIG_DEFAULTS[sentinelKey];
+  }
+});