SPM: unquote before the promotion seed test, and note re-sync in the tradeoff

Review feedback on the promoted-scalar restore:

- The seed guard compared the prior scalar against the quoted
  `"$(inherited)"` only, so an unquoted `$(inherited)` — equally valid, and
  present in the suite's own untrimmed-scalar fixture — was re-emitted
  alongside the seed. Deinit still restored it byte-identically (the record
  is raw), so this was duplication rather than breakage, but it defeated
  the guard. Compare unquoted, and parametrize the guard's unit test over
  both spellings so the injected shape is asserted, not just the
  post-deinit bytes.

- The reversal tradeoff is not deinit-only: every re-sync reverts from the
  recorded baseline before re-injecting, so an `spm update` discards
  hand-added members just the same. Say so in the banner.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: chrfalch

packages/react-native/scripts/spm/__tests__/spm-pbxproj-test.js

@@ -195,25 +195,31 @@ describe('addArrayStringValues', () => {
     expect(out).toContain('"-ObjC"');
   });
 
-  it('promotes a bare "$(inherited)" scalar without emitting it twice', () => {
-    const scalar = PLAIN_PBXPROJ.replace(
-      'PRODUCT_NAME = "$(TARGET_NAME)";',
-      'OTHER_LDFLAGS = "$(inherited)"; PRODUCT_NAME = "$(TARGET_NAME)";',
-    );
-    const out = addArrayStringValues(
-      scalar,
-      targetDebugDict(scalar),
-      'OTHER_LDFLAGS',
-      ['"-ObjC"'],
-    );
-    const members = /OTHER_LDFLAGS = \(\n([\s\S]*?)\t+\);/
-      .exec(out)[1]
-      .split('\n')
-      .map(line => line.trim().replace(/,$/, ''))
-      .filter(member => member.length > 0);
-    // The scalar's value IS the seed the array is created with.
-    expect(members).toEqual(['"$(inherited)"', '"-ObjC"']);
-  });
+  // Xcode writes the seed quoted, but the unquoted form is just as valid and
+  // appears in hand-edited projects. Both are the same value to the build
+  // system, so neither may be re-emitted alongside the seed.
+  it.each(['"$(inherited)"', '$(inherited)'])(
+    'promotes a bare %s scalar without emitting the seed twice',
+    priorValue => {
+      const scalar = PLAIN_PBXPROJ.replace(
+        'PRODUCT_NAME = "$(TARGET_NAME)";',
+        `OTHER_LDFLAGS = ${priorValue}; PRODUCT_NAME = "$(TARGET_NAME)";`,
+      );
+      const out = addArrayStringValues(
+        scalar,
+        targetDebugDict(scalar),
+        'OTHER_LDFLAGS',
+        ['"-ObjC"'],
+      );
+      const members = /OTHER_LDFLAGS = \(\n([\s\S]*?)\t+\);/
+        .exec(out)[1]
+        .split('\n')
+        .map(line => line.trim().replace(/,$/, ''))
+        .filter(member => member.length > 0);
+      // The scalar's value IS the seed the array is created with.
+      expect(members).toEqual(['"$(inherited)"', '"-ObjC"']);
+    },
+  );
 
   it('promotes an empty scalar without emitting a bare `,` member', () => {
     const scalar = PLAIN_PBXPROJ.replace(

packages/react-native/scripts/spm/spm-pbxproj.js

@@ -408,9 +408,12 @@ function addArrayStringValues(
     }
     // Existing scalar — promote to an array preserving the prior value. Skip it
     // when it IS the `"$(inherited)"` the array is seeded with (emitted twice),
-    // or when it is empty (a bare `,` is not a valid plist element).
+    // or when it is empty (a bare `,` is not a valid plist element). The seed
+    // test unquotes first: pbxproj accepts `$(inherited)` bare, and Xcode's own
+    // quoted form is the same value to the build system.
     const prior = field.value.trim();
-    const carriesPrior = prior !== '' && prior !== '"$(inherited)"';
+    const carriesPrior =
+      prior !== '' && prior.replace(/^"(.*)"$/s, '$1') !== '$(inherited)';
     const replacement = arrayBlock([
       '"$(inherited)"',
       ...(carriesPrior ? [prior] : []),
@@ -471,6 +474,8 @@ function setScalarField(
 // user edits made after injection) untouched. The exception is a scalar that
 // injection promoted to an array: reversing that rewrites the whole field (see
 // removeRecordedBuildSettings), so members added to it afterwards are lost.
+// That is not deinit-only — every re-sync reverts from the recorded baseline
+// before re-injecting, so an `spm update` discards them just the same.
 // All are pure string transforms.
 // ---------------------------------------------------------------------------