fix(ini): quote ambiguous string values in stringify to preserve round-trip type

ini/stringify.ts

@@ -43,6 +43,20 @@ function sort([_a, valA]: [string, unknown], [_b, valB]: [string, unknown]) {
 }
 
 function defaultReplacer(_key: string, value: unknown, _section?: string) {
+  if (typeof value === "string") {
+    // Quote strings that would be misread by the parser as a different type.
+    // parseValue converts "true"/"false" to boolean, "null" to null, and
+    // bare numeric strings to number. Wrap those in double quotes so a
+    // parse(stringify(obj)) round-trip preserves the original string value.
+    if (
+      value === "true" ||
+      value === "false" ||
+      value === "null" ||
+      (!isNaN(+value) && value !== "")
+    ) {
+      return `"${value}"`;
+    }
+  }
   return `${value}`;
 }
 

ini/stringify_test.ts

@@ -1,6 +1,6 @@
 // Copyright 2018-2026 the Deno authors. MIT license.
 
-import { stringify } from "./mod.ts";
+import { parse, stringify } from "./mod.ts";
 import { assertEquals } from "@std/assert";
 
 Deno.test({
@@ -39,5 +39,35 @@ Deno.test({
     assertEquals(stringify({ a: false }), "a=false");
     assertEquals(stringify({ a: null }), "a=null");
     assertEquals(stringify({ a: undefined }), "a=undefined");
+
+    // String values that look like other types must be quoted so that
+    // parse(stringify(obj)) preserves the original string value.
+    assertEquals(stringify({ a: "true" }), `a="true"`);
+    assertEquals(stringify({ a: "false" }), `a="false"`);
+    assertEquals(stringify({ a: "null" }), `a="null"`);
+    assertEquals(stringify({ a: "123" }), `a="123"`);
+    assertEquals(stringify({ a: "0" }), `a="0"`);
+    assertEquals(stringify({ a: "3.14" }), `a="3.14"`);
+    // Plain strings that cannot be mistaken for another type are not quoted.
+    assertEquals(stringify({ a: "hello" }), "a=hello");
+    assertEquals(stringify({ a: "123foo" }), "a=123foo");
+  },
+});
+
+Deno.test({
+  name: "stringify() round-trips string values that look like other types",
+  fn() {
+    // All of these were silently corrupted before the fix: the string was
+    // written without quotes and then parsed back as a different type.
+    const obj = {
+      boolTrue: "true",
+      boolFalse: "false",
+      nullVal: "null",
+      num: "42",
+      float: "1.5",
+      zero: "0",
+    };
+    const roundTripped = parse(stringify(obj));
+    assertEquals(roundTripped, obj);
   },
 });