refactor(i18n): route framework + shared chrome through a 'core' catalog (T-469)

Framework strings outside any extension — widget primitives (collapser, toast,
lightbox, multitab, ex-line, spine, pane chrome), the shared reader chrome, the
markdown 'Open in editor' tooltip, and the drag-resize handle a11y labels — now
resolve under a new 'core' namespace (preloaded at boot). Settles the T-469
namespace question: framework chrome gets one 'core' catalog.

Makes ClideSettings.i18n.string/.interpolated null-safe (ClideKernel.maybeOf):
primitives render kernel-less in isolated tests, returning the placeholder —
matching the D-101 fallback contract for fonts. The markdown tooltip threads
via the ClideMarkdownHooks carrier like mono/ui; drag_resize reads the kernel
i18n directly to avoid a kernel→widgets layering inversion. No en_US change.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.pql/changelog/ticket_history/2026-06.sql

@@ -5943,3 +5943,4 @@ INSERT INTO ticket_history (ticket_record_id, field, old_value, new_value, chang
 INSERT INTO ticket_history (ticket_record_id, field, old_value, new_value, changed_by, changed_at, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('06FDA0XMA9BQV4RHJ55BFN4JR4', 'status', 'in_progress', 'done', NULL, '2026-06-18 19:19:25', '2026-06-18 19:19:25.269', '2026-06-18 19:19:25.269', NULL, 'f1660567ecfe0c7220c23244206bc4d2', 2) ON CONFLICT(hash) DO NOTHING;
 INSERT INTO ticket_history (ticket_record_id, field, old_value, new_value, changed_by, changed_at, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('06FDA0YCY2WGSG8W46RHQ5Z9MW', 'status', 'in_progress', 'done', NULL, '2026-06-18 20:13:50', '2026-06-18 20:13:50.352', '2026-06-18 20:13:50.352', NULL, 'a885fb7b56c053669a8ef5f0e6032feb', 2) ON CONFLICT(hash) DO NOTHING;
 INSERT INTO ticket_history (ticket_record_id, field, old_value, new_value, changed_by, changed_at, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('06FDA0YYCJ0NK8C4HMDYKJHRDG', 'status', 'in_progress', 'done', NULL, '2026-06-18 20:16:03', '2026-06-18 20:16:03.747', '2026-06-18 20:16:03.747', NULL, '5e67beaa758d779f1b9212aecb82e050', 2) ON CONFLICT(hash) DO NOTHING;
+INSERT INTO ticket_history (ticket_record_id, field, old_value, new_value, changed_by, changed_at, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('06FDA10DRQE3SED10JAW2CZDCR', 'status', 'backlog', 'done', NULL, '2026-06-18 21:21:27', '2026-06-18 21:21:27.304', '2026-06-18 21:21:27.304', NULL, '0ab235b21c54d46de3e3e4d1529de041', 2) ON CONFLICT(hash) DO NOTHING;

.pql/changelog/tickets/2026-06.sql

@@ -7355,3 +7355,12 @@ Several have no catalog file yet — create lib/kernel/src/i18n/catalog/builtin.
 Can be split into smaller tasks if a single PR is too large; grouped here to keep the long tail in one tracked place.
 
 Acceptance: no hardcoded user-facing literals remain in any of these extensions; each has a catalog file with the keys it uses; no orphaned keys left in editor/files/terminal.', 'done', 'medium', NULL, NULL, 'D-21', '2026-06-17 09:57:41.092', '2026-06-18 20:16:03.746', NULL, '8212472a6e32ec3000b829a7abee3cb9', 2) ON CONFLICT(record_id) DO UPDATE SET type=excluded.type, parent_record_id=excluded.parent_record_id, title=excluded.title, description=excluded.description, status=excluded.status, priority=excluded.priority, assigned_to=excluded.assigned_to, team=excluded.team, decision_ref=excluded.decision_ref, updated_at=excluded.updated_at, deleted_at=excluded.deleted_at, hash=excluded.hash, canonical_version=excluded.canonical_version WHERE excluded.updated_at > tickets.updated_at OR (excluded.updated_at = tickets.updated_at AND excluded.hash > tickets.hash);
+INSERT INTO tickets (record_id, type, parent_record_id, title, description, status, priority, assigned_to, team, decision_ref, created_at, updated_at, deleted_at, hash, canonical_version) VALUES ('06FDA10DRQE3SED10JAW2CZDCR', 'task', '06FDA0TPYSWEM10RP0Q76XAP58', 'i18n: route framework-level labels in lib/widgets + lib/kernel (~10 strings)', '~9 hardcoded user-facing strings in lib/widgets/ and ~1 in lib/kernel/ live outside any extension, so they have no obvious i18n namespace. Resolve the namespace question, then migrate.
+
+Hotspots from the audit:
+- lib/widgets/src/ex_line_overlay.dart:163 '':'' , :183 ''Not an editor command'' (these are vim ex-line — may belong to builtin.vim''s namespace rather than a generic one)
+- lib/widgets/src/multitab_pane.dart:358 ''+''  (likely an icon glyph — exempt if so)
+
+Open question to settle in this task: do framework widgets get a ''core''/''kernel'' namespace, or does each caller pass its owning extension''s namespace down? Pick one and note it (small D- or Q- record if it sets precedent). Single-char icon glyphs (''+'', '':'') are exempt — note any left.
+
+Acceptance: real user-facing sentences in lib/widgets + lib/kernel resolve through i18n under a documented namespace; glyph exemptions noted.', 'done', 'low', NULL, NULL, 'D-21', '2026-06-17 09:57:53.221', '2026-06-18 21:21:27.304', NULL, '9817d717fa77916d07547d9674d14fcb', 2) ON CONFLICT(record_id) DO UPDATE SET type=excluded.type, parent_record_id=excluded.parent_record_id, title=excluded.title, description=excluded.description, status=excluded.status, priority=excluded.priority, assigned_to=excluded.assigned_to, team=excluded.team, decision_ref=excluded.decision_ref, updated_at=excluded.updated_at, deleted_at=excluded.deleted_at, hash=excluded.hash, canonical_version=excluded.canonical_version WHERE excluded.updated_at > tickets.updated_at OR (excluded.updated_at = tickets.updated_at AND excluded.hash > tickets.hash);

lib/builtin/shared/reader_chrome.dart

@@ -50,22 +50,40 @@ class ReaderActionBar extends StatelessWidget {
     return Row(
       mainAxisSize: MainAxisSize.min,
       children: [
-        _ActionButton(painter: PhosphorIcons.byName('caret-left'), tooltip: 'Back', enabled: canGoBack, onTap: canGoBack ? onBack : null, tokens: tokens),
+        _ActionButton(
+          painter: PhosphorIcons.byName('caret-left'),
+          tooltip: ClideSettings.i18n.string(context, 'reader.back', namespace: 'core', placeholder: 'Back'),
+          enabled: canGoBack,
+          onTap: canGoBack ? onBack : null,
+          tokens: tokens,
+        ),
         const SizedBox(width: 2),
         _ActionButton(
           painter: PhosphorIcons.byName('caret-right'),
-          tooltip: 'Forward',
+          tooltip: ClideSettings.i18n.string(context, 'reader.forward', namespace: 'core', placeholder: 'Forward'),
           enabled: canGoForward,
           onTap: canGoForward ? onForward : null,
           tokens: tokens,
         ),
         if (hasPinned) ...[
           const SizedBox(width: 2),
-          _ActionButton(painter: PhosphorIcons.byName('arrow-u-up-left'), tooltip: 'Jump to pin', enabled: true, onTap: onJumpToPin, tokens: tokens),
+          _ActionButton(
+            painter: PhosphorIcons.byName('arrow-u-up-left'),
+            tooltip: ClideSettings.i18n.string(context, 'reader.jumpToPin', namespace: 'core', placeholder: 'Jump to pin'),
+            enabled: true,
+            onTap: onJumpToPin,
+            tokens: tokens,
+          ),
         ],
         if (onEdit != null) ...[
           const SizedBox(width: 4),
-          _ActionButton(painter: PhosphorIcons.byName('pencil-simple'), tooltip: 'Edit in editor', enabled: true, onTap: onEdit, tokens: tokens),
+          _ActionButton(
+            painter: PhosphorIcons.byName('pencil-simple'),
+            tooltip: ClideSettings.i18n.string(context, 'reader.edit', namespace: 'core', placeholder: 'Edit in editor'),
+            enabled: true,
+            onTap: onEdit,
+            tokens: tokens,
+          ),
         ],
       ],
     );
@@ -86,7 +104,9 @@ class ReaderPinButton extends StatelessWidget {
   Widget build(BuildContext context) {
     return _ActionButton(
       painter: PhosphorIcons.byName('push-pin'),
-      tooltip: pinned ? 'Unpin' : 'Pin',
+      tooltip: pinned
+          ? ClideSettings.i18n.string(context, 'reader.unpin', namespace: 'core', placeholder: 'Unpin')
+          : ClideSettings.i18n.string(context, 'reader.pin', namespace: 'core', placeholder: 'Pin'),
       enabled: onTap != null,
       active: pinned,
       onTap: onTap,

lib/kernel/src/facade.dart

@@ -345,6 +345,11 @@ class ClideKernel extends InheritedWidget {
     return w.services;
   }
 
+  /// Like [of] but returns null instead of throwing when there is no kernel in
+  /// scope — lets widget-facing facades (e.g. [ClideSettings.i18n]) degrade
+  /// gracefully so a primitive renders in an isolated test without a kernel.
+  static KernelServices? maybeOf(BuildContext context) => context.dependOnInheritedWidgetOfExactType<ClideKernel>()?.services;
+
   @override
   bool updateShouldNotify(ClideKernel oldWidget) => services != oldWidget.services;
 }

lib/kernel/src/i18n/catalog/core_en_us.json

@@ -0,0 +1,27 @@
+{
+  "collapser.expand": { "translation": "Expand" },
+  "collapser.collapse": { "translation": "Collapse" },
+  "collapser.expanded": { "translation": "expanded" },
+  "collapser.collapsed": { "translation": "collapsed" },
+  "toast.dismiss": { "translation": "Dismiss notification" },
+  "lightbox.close": { "translation": "close" },
+  "lightbox.hint": { "translation": "scroll to zoom · double-click to reset · Esc to close" },
+  "tab.new": { "translation": "New tab" },
+  "exline.notCommand": { "translation": "Not an editor command" },
+  "spine.expandSuffix": { "translation": "click to expand" },
+  "pane.close": { "translation": "Close pane" },
+  "pane.header": { "translation": "pane header: {title}" },
+  "reader.back": { "translation": "Back" },
+  "reader.forward": { "translation": "Forward" },
+  "reader.jumpToPin": { "translation": "Jump to pin" },
+  "reader.edit": { "translation": "Edit in editor" },
+  "reader.pin": { "translation": "Pin" },
+  "reader.unpin": { "translation": "Unpin" },
+  "link.openInEditor": { "translation": "Open in editor" },
+  "resize.axis.width": { "translation": "width" },
+  "resize.axis.height": { "translation": "height" },
+  "resize.sidebar": { "translation": "Sidebar {axis}" },
+  "resize.contextPanel": { "translation": "Context panel {axis}" },
+  "resize.slot": { "translation": "{slot} {axis}" },
+  "resize.pixels": { "translation": "{n} pixels" }
+}

lib/kernel/src/panels/drag_resize.dart

@@ -1,3 +1,5 @@
+import 'package:clide/kernel/src/facade.dart' show ClideKernel;
+import 'package:clide/kernel/src/i18n/i18n.dart' show I18nReplacer;
 import 'package:clide/kernel/src/panels/arrangement.dart';
 import 'package:clide/kernel/src/panels/slot_id.dart';
 import 'package:clide/kernel/src/theme/controller.dart';
@@ -43,10 +45,10 @@ class _DragResizeHandleState extends State<DragResizeHandle> {
     return Semantics(
       container: true,
       slider: true,
-      label: _semanticLabel(),
-      value: size == null ? null : '${size.round()} pixels',
-      increasedValue: size == null ? null : '${(size + DragResizeHandle.stepFine).round()} pixels',
-      decreasedValue: size == null ? null : '${(size - DragResizeHandle.stepFine).round()} pixels',
+      label: _semanticLabel(context),
+      value: size == null ? null : _pixels(context, size.round()),
+      increasedValue: size == null ? null : _pixels(context, (size + DragResizeHandle.stepFine).round()),
+      decreasedValue: size == null ? null : _pixels(context, (size - DragResizeHandle.stepFine).round()),
       onIncrease: () => _bump(DragResizeHandle.stepFine),
       onDecrease: () => _bump(-DragResizeHandle.stepFine),
       child: FocusableActionDetector(
@@ -87,11 +89,55 @@ class _DragResizeHandleState extends State<DragResizeHandle> {
     );
   }
 
-  String _semanticLabel() {
-    final axis = widget.axis == Axis.horizontal ? 'width' : 'height';
-    if (widget.slot == Slots.sidebar) return 'Sidebar $axis';
-    if (widget.slot == Slots.contextPanel) return 'Context panel $axis';
-    return '${widget.slot.value} $axis';
+  /// The slider's accessible name (D-21, `core` namespace). With no kernel in
+  /// scope (isolated tests) the i18n lookups fall back to the English
+  /// placeholders, mirroring the widget-facing facade's degrade behaviour.
+  String _semanticLabel(BuildContext context) {
+    final i18n = ClideKernel.maybeOf(context)?.i18n;
+    final axis = widget.axis == Axis.horizontal
+        ? (i18n?.string('resize.axis.width', namespace: 'core', placeholder: 'width') ?? 'width')
+        : (i18n?.string('resize.axis.height', namespace: 'core', placeholder: 'height') ?? 'height');
+    if (widget.slot == Slots.sidebar) {
+      return i18n?.interpolated(
+            'resize.sidebar',
+            namespace: 'core',
+            placeholder: 'Sidebar {axis}',
+            replacers: [I18nReplacer(from: '{axis}', replace: axis)],
+          ) ??
+          'Sidebar $axis';
+    }
+    if (widget.slot == Slots.contextPanel) {
+      return i18n?.interpolated(
+            'resize.contextPanel',
+            namespace: 'core',
+            placeholder: 'Context panel {axis}',
+            replacers: [I18nReplacer(from: '{axis}', replace: axis)],
+          ) ??
+          'Context panel $axis';
+    }
+    return i18n?.interpolated(
+          'resize.slot',
+          namespace: 'core',
+          placeholder: '{slot} {axis}',
+          replacers: [
+            I18nReplacer(from: '{slot}', replace: widget.slot.value),
+            I18nReplacer(from: '{axis}', replace: axis),
+          ],
+        ) ??
+        '${widget.slot.value} $axis';
+  }
+
+  /// `'{n} pixels'` via the `core` catalog (falls back to English with no
+  /// kernel in scope).
+  String _pixels(BuildContext context, int n) {
+    final i18n = ClideKernel.maybeOf(context)?.i18n;
+    return i18n?.interpolated(
+          'resize.pixels',
+          namespace: 'core',
+          placeholder: '{n} pixels',
+          replacers: [I18nReplacer(from: '{n}', replace: '$n')],
+        ) ??
+        '$n pixels';
   }
 
   Map<ShortcutActivator, Intent> _shortcuts() {

lib/main.dart

@@ -557,6 +557,9 @@ Future<List<ThemeDefinition>> _loadBundledThemes() async {
 /// catalogs load lazily on activate in later tiers.
 
 const List<String> _tier0Namespaces = [
+  // Framework chrome that lives outside any extension (lib/widgets, lib/kernel,
+  // shared reader chrome) resolves under the 'core' namespace (T-469).
+  'core',
   'builtin.default-layout',
   'builtin.welcome',
   'builtin.ipc-status',

lib/widgets/src/clide_collapser_card.dart

@@ -90,7 +90,7 @@ class _ClideCollapserCardState extends State<ClideCollapserCard> {
     final tokens = ClideSettings.theme.of(context).surface;
     return Padding(
       padding: const EdgeInsets.only(bottom: kClideCardGap),
-      child: _expanded ? _expandedFrame(tokens) : _tickerRow(tokens),
+      child: _expanded ? _expandedFrame(context, tokens) : _tickerRow(context, tokens),
     );
   }
 
@@ -98,15 +98,12 @@ class _ClideCollapserCardState extends State<ClideCollapserCard> {
   /// wrapping the whole card excluded every expanded child from the a11y
   /// tree, so a screen-reader user could expand a run and hear nothing
   /// inside it (T-370). Collapsed, the header summary IS the whole card.
-  Widget _headerSemantics({required Widget child}) {
+  Widget _headerSemantics(BuildContext context, {required Widget child}) {
     final semanticCount = widget.counter == null ? '' : ', ${widget.counter}';
-    return Semantics(
-      button: true,
-      expanded: _expanded,
-      label: '${widget.label}$semanticCount, ${_expanded ? 'expanded' : 'collapsed'}',
-      excludeSemantics: true,
-      child: child,
-    );
+    final stateWord = _expanded
+        ? ClideSettings.i18n.string(context, 'collapser.expanded', namespace: 'core', placeholder: 'expanded')
+        : ClideSettings.i18n.string(context, 'collapser.collapsed', namespace: 'core', placeholder: 'collapsed');
+    return Semantics(button: true, expanded: _expanded, label: '${widget.label}$semanticCount, $stateWord', excludeSemantics: true, child: child);
   }
 
   /// The header row content, shared by the collapsed ticker and the expanded
@@ -154,11 +151,12 @@ class _ClideCollapserCardState extends State<ClideCollapserCard> {
   }
 
   /// Collapsed: the ticker row IS the toggle, focusable for keyboard/AT.
-  Widget _tickerRow(SurfaceTokens tokens) => _headerSemantics(
+  Widget _tickerRow(BuildContext context, SurfaceTokens tokens) => _headerSemantics(
+    context,
     child: ClideTappable(
       focusNode: _controlFocus,
       onTap: _toggle,
-      tooltip: 'Expand',
+      tooltip: ClideSettings.i18n.string(context, 'collapser.expand', namespace: 'core', placeholder: 'Expand'),
       builder: (context, hovered, focused) => Container(
         padding: const EdgeInsets.symmetric(horizontal: kClideCardHeaderPadH, vertical: kClideCardHeaderPadV),
         decoration: BoxDecoration(
@@ -174,7 +172,7 @@ class _ClideCollapserCardState extends State<ClideCollapserCard> {
   /// Expanded: a framed inner canvas wrapping the item cards. The frame
   /// BACKGROUND is a gesture target behind the items that only fires for hits
   /// the items don't consume.
-  Widget _expandedFrame(SurfaceTokens tokens) => DecoratedBox(
+  Widget _expandedFrame(BuildContext context, SurfaceTokens tokens) => DecoratedBox(
     decoration: BoxDecoration(
       border: Border.all(color: widget.color ?? tokens.panelBorder),
       borderRadius: BorderRadius.circular(kClideCardRadius),
@@ -187,14 +185,18 @@ class _ClideCollapserCardState extends State<ClideCollapserCard> {
         Positioned.fill(
           child: ExcludeFocus(
             child: ExcludeSemantics(
-              child: ClideTappable(onTap: _toggle, tooltip: 'Collapse', builder: (_, _, _) => const SizedBox.expand()),
+              child: ClideTappable(
+                onTap: _toggle,
+                tooltip: ClideSettings.i18n.string(context, 'collapser.collapse', namespace: 'core', placeholder: 'Collapse'),
+                builder: (_, _, _) => const SizedBox.expand(),
+              ),
             ),
           ),
         ),
         Column(
           crossAxisAlignment: CrossAxisAlignment.stretch,
           children: [
-            _headerSemantics(child: _headerRow(tokens)),
+            _headerSemantics(context, child: _headerRow(context, tokens)),
             // Even padding around the inner item canvas (T-305): the sides +
             // top match, and each inner item carries a matching bottom margin
             // (so the last item's margin is the bottom inset and items in a
@@ -222,10 +224,10 @@ class _ClideCollapserCardState extends State<ClideCollapserCard> {
   /// The explicit, focusable collapse control in the expanded header. A
   /// background tap alone is not keyboard/AT reachable, so this keeps the
   /// control on the Tab path and Enter/Space-activatable (D-78).
-  Widget _headerRow(SurfaceTokens tokens) => ClideTappable(
+  Widget _headerRow(BuildContext context, SurfaceTokens tokens) => ClideTappable(
     focusNode: _controlFocus,
     onTap: _toggle,
-    tooltip: 'Collapse',
+    tooltip: ClideSettings.i18n.string(context, 'collapser.collapse', namespace: 'core', placeholder: 'Collapse'),
     builder: (context, hovered, focused) => Container(
       padding: const EdgeInsets.symmetric(horizontal: kClideCardHeaderPadH, vertical: kClideCardHeaderPadV),
       decoration: BoxDecoration(

lib/widgets/src/clide_lightbox.dart

@@ -145,7 +145,12 @@ class _ClideLightboxState extends State<ClideLightbox> {
             Positioned(
               top: 8,
               right: 8,
-              child: _IconChip(icon: PhosphorIcons.byName('x'), label: 'close', onTap: widget.onDismiss, tokens: tokens),
+              child: _IconChip(
+                icon: PhosphorIcons.byName('x'),
+                label: ClideSettings.i18n.string(context, 'lightbox.close', namespace: 'core', placeholder: 'close'),
+                onTap: widget.onDismiss,
+                tokens: tokens,
+              ),
             ),
             Positioned(
               bottom: 8,
@@ -156,7 +161,16 @@ class _ClideLightboxState extends State<ClideLightbox> {
                   decoration: BoxDecoration(color: tokens.panelHeader, borderRadius: BorderRadius.circular(4)),
                   child: Padding(
                     padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 3),
-                    child: ClideText('scroll to zoom · double-click to reset · Esc to close', fontSize: clideFontMeta, color: tokens.globalTextMuted),
+                    child: ClideText(
+                      ClideSettings.i18n.string(
+                        context,
+                        'lightbox.hint',
+                        namespace: 'core',
+                        placeholder: 'scroll to zoom · double-click to reset · Esc to close',
+                      ),
+                      fontSize: clideFontMeta,
+                      color: tokens.globalTextMuted,
+                    ),
                   ),
                 ),
               ),

lib/widgets/src/clide_markdown.dart

@@ -43,6 +43,7 @@ class ClideMarkdownHooks {
     this.onOpenFile,
     this.mono = clideMonoFamily,
     this.ui = clideUiFamily,
+    this.openInEditor = 'Open in editor',
   });
 
   /// Tap a governance/ticket ref (T-281, D-77, …) → open the record (T-279).
@@ -72,6 +73,11 @@ class ClideMarkdownHooks {
   /// pinning the bundled default (T-475).
   final String ui;
 
+  /// The resolved 'Open in editor' tooltip for file-ref link spans, threaded
+  /// the same way as [mono]/[ui] so the context-free static span builders can
+  /// use the i18n catalog string (D-21, `core` namespace) instead of a literal.
+  final String openInEditor;
+
   static const none = ClideMarkdownHooks();
 }
 
@@ -137,6 +143,7 @@ class ClideMarkdown extends StatelessWidget {
       onOpenFile: onOpenFile,
       mono: ClideSettings.fonts.monoOf(context),
       ui: ClideSettings.fonts.uiOf(context),
+      openInEditor: ClideSettings.i18n.string(context, 'link.openInEditor', namespace: 'core', placeholder: 'Open in editor'),
     );
     final widgets = _buildNodes(nodes, tokens, hooks);
     return Column(crossAxisAlignment: CrossAxisAlignment.stretch, mainAxisSize: MainAxisSize.min, children: widgets);
@@ -393,7 +400,7 @@ class ClideMarkdown extends StatelessWidget {
         // editor (T-300); other inline code renders verbatim.
         if (hooks.resolveFileRef != null && hooks.onOpenFile != null) {
           final ref = _codeFileRef(raw, hooks.resolveFileRef!);
-          if (ref != null) return _fileLinkSpan(raw, ref.$1, ref.$2, tokens, hooks.onOpenFile!, hooks.mono, hooks.ui, mono: true);
+          if (ref != null) return _fileLinkSpan(raw, ref.$1, ref.$2, tokens, hooks.onOpenFile!, hooks.mono, hooks.ui, hooks.openInEditor, mono: true);
         }
         return TextSpan(
           text: raw,
@@ -415,7 +422,7 @@ class ClideMarkdown extends StatelessWidget {
         if (hooks.resolveFileRef != null && hooks.onOpenFile != null && href != null) {
           final (path, line) = _splitFileRef(href);
           final abs = hooks.resolveFileRef!(path);
-          if (abs != null) return _fileLinkSpan(text, abs, line, tokens, hooks.onOpenFile!, hooks.mono, hooks.ui);
+          if (abs != null) return _fileLinkSpan(text, abs, line, tokens, hooks.onOpenFile!, hooks.mono, hooks.ui, hooks.openInEditor);
         }
         return TextSpan(
           text: text,
@@ -496,7 +503,13 @@ class ClideMarkdown extends StatelessWidget {
         final abs = hooks.resolveFileRef!(m.group(1)!);
         if (abs == null) continue;
         final line = m.group(2) == null ? null : int.tryParse(m.group(2)!);
-        hits.add(_LinkHit(m.start, m.end, _fileLinkSpan(text.substring(m.start, m.end), abs, line, tokens, hooks.onOpenFile!, hooks.mono, hooks.ui)));
+        hits.add(
+          _LinkHit(
+            m.start,
+            m.end,
+            _fileLinkSpan(text.substring(m.start, m.end), abs, line, tokens, hooks.onOpenFile!, hooks.mono, hooks.ui, hooks.openInEditor),
+          ),
+        );
       }
     }
     if (hits.isEmpty) return [TextSpan(text: text)];
@@ -575,7 +588,8 @@ class ClideMarkdown extends StatelessWidget {
     SurfaceTokens tokens,
     FileTapCallback onOpenFile,
     String monoFamily,
-    String uiFamily, {
+    String uiFamily,
+    String openInEditor, {
     bool mono = false,
   }) {
     return WidgetSpan(
@@ -583,7 +597,7 @@ class ClideMarkdown extends StatelessWidget {
       baseline: TextBaseline.alphabetic,
       child: ClideTappable(
         onTap: () => onOpenFile(absPath, line),
-        tooltip: 'Open in editor',
+        tooltip: openInEditor,
         builder: (_, hovered, _) => Text(
           display,
           style: TextStyle(

lib/widgets/src/clide_pane_chrome.dart

@@ -60,13 +60,14 @@ class _CloseButton extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     final tokens = ClideSettings.theme.of(context).surface;
+    final closeLabel = ClideSettings.i18n.string(context, 'pane.close', namespace: 'core', placeholder: 'Close pane');
     return Semantics(
       button: true,
-      label: 'Close pane',
+      label: closeLabel,
       onTap: onPressed,
       child: ClideTappable(
         onTap: onPressed,
-        tooltip: 'Close pane',
+        tooltip: closeLabel,
         builder: (context, hovered, _) => Container(
           width: 20,
           height: 20,
@@ -94,7 +95,13 @@ class _Header extends StatelessWidget {
     return Semantics(
       container: true,
       explicitChildNodes: true,
-      label: 'pane header: $title',
+      label: ClideSettings.i18n.interpolated(
+        context,
+        'pane.header',
+        namespace: 'core',
+        placeholder: 'pane header: {title}',
+        replacers: [I18nReplacer(from: '{title}', replace: title)],
+      ),
       child: ColoredBox(
         color: tokens.panelHeader,
         child: Padding(

lib/widgets/src/clide_settings.dart

@@ -52,13 +52,23 @@ class _I18n {
 
   /// Resolve a catalog string through the live i18n service (D-21) — the
   /// uniform widget-facing lookup (T-462). [placeholder] is the inline English
-  /// fallback rendered until/unless the catalog covers the key.
-  String string(BuildContext context, String key, {required String namespace, String? placeholder}) =>
-      of(context).string(key, namespace: namespace, placeholder: placeholder);
+  /// fallback. With no kernel in scope (isolated primitive tests) it returns
+  /// the placeholder, so a widget never needs one to render.
+  String string(BuildContext context, String key, {required String namespace, String? placeholder}) {
+    final i = ClideKernel.maybeOf(context)?.i18n;
+    return i == null ? (placeholder ?? key) : i.string(key, namespace: namespace, placeholder: placeholder);
+  }
 
   /// [string] with `replaceAll` interpolation per replacer (templated labels).
-  String interpolated(BuildContext context, String key, {required String namespace, String? placeholder, List<I18nReplacer> replacers = const []}) =>
-      of(context).interpolated(key, namespace: namespace, placeholder: placeholder, replacers: replacers);
+  String interpolated(BuildContext context, String key, {required String namespace, String? placeholder, List<I18nReplacer> replacers = const []}) {
+    final i = ClideKernel.maybeOf(context)?.i18n;
+    if (i != null) return i.interpolated(key, namespace: namespace, placeholder: placeholder, replacers: replacers);
+    var out = placeholder ?? key;
+    for (final r in replacers) {
+      out = out.replaceAll(r.from, r.replace);
+    }
+    return out;
+  }
 }
 
 /// Root-provided InheritedWidget carrying the live font families (D-101). The

lib/widgets/src/clide_spine.dart

@@ -19,9 +19,10 @@ class ClideSpine extends StatelessWidget {
     final tokens = ClideSettings.theme.of(context).surface;
     final borderSide = BorderSide(color: tokens.dividerColor);
 
+    final expandSuffix = ClideSettings.i18n.string(context, 'spine.expandSuffix', namespace: 'core', placeholder: 'click to expand');
     return Semantics(
       button: true,
-      label: '$label — click to expand',
+      label: '$label — $expandSuffix',
       child: ClideTappable(
         onTap: onExpand,
         builder: (context, hovered, _) => Container(

lib/widgets/src/clide_toast.dart

@@ -86,7 +86,7 @@ class _ClideToastState extends State<ClideToast> {
                   const SizedBox(width: clideGapStandard),
                   Semantics(
                     button: true,
-                    label: 'Dismiss notification',
+                    label: ClideSettings.i18n.string(context, 'toast.dismiss', namespace: 'core', placeholder: 'Dismiss notification'),
                     child: ClideTappable(
                       onTap: widget.onDismiss,
                       builder: (ctx, hovered, _) =>

lib/widgets/src/ex_line_overlay.dart

@@ -181,7 +181,11 @@ class _ExLineOverlayState extends State<ExLineOverlay> {
                     if (_rejected)
                       Padding(
                         padding: const EdgeInsets.symmetric(horizontal: 12, vertical: 6),
-                        child: ClideText('Not an editor command', fontSize: clideFontCaption, color: tokens.statusError),
+                        child: ClideText(
+                          ClideSettings.i18n.string(context, 'exline.notCommand', namespace: 'core', placeholder: 'Not an editor command'),
+                          fontSize: clideFontCaption,
+                          color: tokens.statusError,
+                        ),
                       ),
                   ],
                 ),

lib/widgets/src/multitab_pane.dart

@@ -346,7 +346,7 @@ class _AddButton extends StatelessWidget {
     final tokens = ClideSettings.theme.of(context).surface;
     return Semantics(
       button: true,
-      label: 'New tab',
+      label: ClideSettings.i18n.string(context, 'tab.new', namespace: 'core', placeholder: 'New tab'),
       excludeSemantics: true,
       child: ClideTappable(
         onTap: onTap,