row 283 (#1788): E2 per sage-3601: editor values with surrounding whitespace refuse library-mapping-invalid (git trims idents at commit); T3 padded cases per key, mutant M6c; BUILD.md records the departure from DESIGN.md section 1 and the fixture grep (none). Untested

agents/honker/work/queue-283/BUILD.md

@@ -121,3 +121,26 @@ on the named test and the restored file's sha256 equals the build tip's.
   the commit ident can differ. DESIGN.md section 1 says "non-empty after trim". Refusing
   `value.trim() !== value` would change that approved rule, so it went to Sage instead of into the
   build.
+
+## 2026-10-23 E2 departure (sage-3601)
+
+A departure from DESIGN.md section 1 (which stays unedited). The design says each `editor` value is
+"non-empty after trim". Sage ruled that surrounding whitespace refuses too, because git trims an
+ident at commit, so a padded value would save one name and commit another. mapping.mjs now adds
+`if (value.trim() !== value) bad(`editor.${key} must not start or end with whitespace`)` after the
+IDENT_BAD check. `trim()` covers Unicode whitespace, so U+00A0 and U+3000 refuse as well. Inner
+whitespace is kept ("Her  Middle Name" passes).
+
+T3 gains a case per key for leading, trailing and both-ends spaces, U+00A0 and U+3000, plus one inner
+whitespace pass.
+
+M6 grows a third part:
+
+| Mutant | File | Replace | With | Killed by |
+|---|---|---|---|---|
+| M6c | src/mapping.mjs | `if (value.trim() !== value) bad(` | `if (false && value.trim() !== value) bad(` | mapping.test "editor is optional" (padded cases) |
+
+Fixture grep: `git grep -nE "\beditor\b|\bauthor\b" -- 'packages/library/tests/*' 'packages/business/tests/*'`,
+leaving out mapping.test.mjs, finds nothing. packages/business/tests has no fixtures directory. The
+library fixture mapping.json has no `editor`. The positive control (`vaultPrefix` in mapping.json)
+matches once. No fixture maps an editor or author with surrounding whitespace.

packages/library/src/mapping.mjs

@@ -63,6 +63,8 @@ export function checkMapping(entry, where = 'library', { fail = raise } = {}) {
       const value = entry.editor[key];
       if (typeof value !== 'string' || !value.trim() || IDENT_BAD.test(value))
         bad(`editor.${key} must be non-empty text with no control character, < or >`);
+      // Git trims an ident at commit, so a padded value would save one name and commit another (sage-3601).
+      if (value.trim() !== value) bad(`editor.${key} must not start or end with whitespace`);
     }
   }
 

packages/library/tests/mapping.test.mjs

@@ -121,6 +121,12 @@ test('C2-01d: editor is optional, kept when given, and refuses anything but a pl
     invalid({ ...editor, name: bad }, /editor.name must be non-empty text with no control character, < or >/);
     invalid({ ...editor, email: bad }, /editor.email must be non-empty text with no control character, < or >/);
   }
+  // sage-3601: git trims an ident at commit, so surrounding whitespace refuses.
+  for (const padded of [' Her Name', 'Her Name ', ' Her Name ', '\u00a0Her Name', 'Her Name\u3000']) {
+    invalid({ ...editor, name: padded }, /editor.name must not start or end with whitespace/);
+    invalid({ ...editor, email: padded }, /editor.email must not start or end with whitespace/);
+  }
+  assert.equal(mapping(e => ({ ...e, editor: { name: 'Her  Middle Name', email: '[email protected]' } })).editor.name, 'Her  Middle Name');
 });
 
 test('no playground prefix holds another, and no book folder holds another', () => {