diff --git a/pubspec.yaml b/pubspec.yaml
index 4d0aa330..794c6130 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -18,7 +18,7 @@ repository: https://github.com/postmeridiem/clide
 
 # Pre-push line-coverage floor. Ratchets up only — see D-66.
 # Reading: `awk -F: '/^coverage_floor:/ {gsub(/ /,"",$2); print $2}' pubspec.yaml`.
-coverage_floor: 74
+coverage_floor: 75
 
 # Project metadata (was project.yaml, folded in per D-056).
 # version: above is the single source of truth. The Makefile reads
diff --git a/test/editor/registry_test.dart b/test/editor/registry_test.dart
index e46d3dba..8be218a4 100644
--- a/test/editor/registry_test.dart
+++ b/test/editor/registry_test.dart
@@ -93,4 +93,62 @@ void main() {
     expect(buf.content, isEmpty);
     expect(buf.dirty, isFalse);
   });
+
+  test('activate(unknown id) is a no-op; activate(known) flips the active buffer', () async {
+    final a = await reg.open('README.md');
+    final b = await reg.open('NEW.md');
+    // b is currently active.
+    expect(reg.active, same(b));
+    sink.events.clear();
+    reg.activate('does-not-exist'); // no-op, no emit
+    expect(sink.ofKind('editor.active-changed'), isEmpty);
+    reg.activate(a.id);
+    expect(reg.active, same(a));
+    expect(sink.ofKind('editor.active-changed'), hasLength(1));
+  });
+
+  test('setContent with explicit selection clamps + emits editor.edited replace', () async {
+    final buf = await reg.open('README.md');
+    sink.events.clear();
+    reg.setContent(buf.id, 'short', selection: const Selection(start: 1, end: 99));
+    expect(buf.content, 'short');
+    // 99 clamped to content.length (5).
+    expect(buf.selection.end, 5);
+    expect(buf.dirty, isTrue);
+    final emitted = sink.ofKind('editor.edited').single;
+    expect(emitted.data['kind'], 'replace');
+    expect(emitted.data['length'], 5);
+  });
+
+  test('setContent without selection clamps the existing selection to the new content', () async {
+    final buf = await reg.open('README.md');
+    reg.setSelection(buf.id, const Selection(start: 6, end: 8));
+    expect(buf.selection.start, 6);
+    reg.setContent(buf.id, 'XY'); // shorter than the selection's offsets
+    expect(buf.content, 'XY');
+    expect(buf.selection.start, 2);
+    expect(buf.selection.end, 2);
+  });
+
+  test('setContent on a missing id is a silent no-op', () {
+    sink.events.clear();
+    reg.setContent('no-such-id', 'whatever');
+    expect(sink.events, isEmpty);
+  });
+
+  test('contentFromArgs decodes content_b64 when text is absent', () {
+    expect(EditorRegistry.contentFromArgs({'text': 'plain'}), 'plain');
+    expect(
+      EditorRegistry.contentFromArgs({'content_b64': 'aGVsbG8='}),
+      'hello',
+    );
+    expect(EditorRegistry.contentFromArgs(const {}), '');
+  });
+
+  test('Selection hashCode + toString round-trip and serialise', () {
+    const s = Selection(start: 3, end: 7);
+    expect(s.hashCode, const Selection(start: 3, end: 7).hashCode);
+    expect(s.hashCode, isNot(equals(const Selection(start: 3, end: 8).hashCode)));
+    expect(s.toString(), 'Selection(3-7)');
+  });
 }