dynamic context panel tabs — spawn on demand, no empty placeholders

Context panel tabs are no longer static. Extensions spawn them
dynamically when relevant and despawn on deactivate:
- Tickets: detail tab spawns on builtin.tickets/selection
- Decisions: detail tab spawns on builtin.decisions/selection
- Backlinks: spawns when editor opens a file
- Markdown viewer: spawns when editor opens a .md file
- Graph: removed from static context (will be command-spawnable)

The icon rail only shows what's active — no empty tabs sitting
there waiting for content.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/builtin/decisions/src/extension.dart

@@ -1,7 +1,10 @@
+import 'dart:async';
+
 import 'package:clide/builtin/decisions/src/decision_detail_view.dart';
 import 'package:clide/builtin/decisions/src/decisions_view.dart';
 import 'package:clide/extension/extension.dart';
 import 'package:clide/kernel/kernel.dart';
+import 'package:clide/kernel/src/events/message_bus.dart';
 
 class DecisionsExtension extends ClideExtension {
   @override
@@ -9,10 +12,14 @@ class DecisionsExtension extends ClideExtension {
   @override
   String get title => 'Decisions';
   @override
-  String get version => '0.2.0';
+  String get version => '0.3.0';
   @override
   List<String> get dependsOn => const [];
 
+  ClideExtensionContext? _ctx;
+  StreamSubscription<Message>? _selectionSub;
+  bool _detailSpawned = false;
+
   @override
   List<ContributionPoint> get contributions => [
         TabContribution(
@@ -24,12 +31,40 @@ class DecisionsExtension extends ClideExtension {
           priority: -20,
           build: (_) => const DecisionsView(),
         ),
-        TabContribution(
-          id: 'decisions.detail',
-          slot: Slots.contextPanel,
-          title: 'Decision',
-          priority: -50,
-          build: (_) => const DecisionDetailView(),
-        ),
       ];
+
+  @override
+  Future<void> activate(ClideExtensionContext ctx) async {
+    _ctx = ctx;
+    _selectionSub = ctx.messages.subscribe(publisher: id, channel: 'selection').listen(_onSelection);
+  }
+
+  @override
+  Future<void> deactivate() async {
+    _selectionSub?.cancel();
+    _despawnDetail();
+  }
+
+  void _onSelection(Message msg) {
+    final ctx = _ctx;
+    if (ctx == null) return;
+    if (!_detailSpawned) {
+      ctx.panels.contribute(TabContribution(
+        id: 'decisions.detail',
+        slot: Slots.contextPanel,
+        title: 'Decision',
+        priority: -50,
+        build: (_) => const DecisionDetailView(),
+      ));
+      _detailSpawned = true;
+    }
+    ctx.panels.activateTab(Slots.contextPanel, 'decisions.detail');
+  }
+
+  void _despawnDetail() {
+    if (_detailSpawned) {
+      _ctx?.panels.uncontribute('decisions.detail');
+      _detailSpawned = false;
+    }
+  }
 }

lib/builtin/graph/src/extension.dart

@@ -1,6 +1,4 @@
-import 'package:clide/builtin/graph/src/graph_view.dart';
 import 'package:clide/extension/extension.dart';
-import 'package:clide/kernel/kernel.dart';
 
 class GraphExtension extends ClideExtension {
   @override
@@ -13,15 +11,5 @@ class GraphExtension extends ClideExtension {
   List<String> get dependsOn => const ['builtin.pql'];
 
   @override
-  List<ContributionPoint> get contributions => [
-        TabContribution(
-          id: 'graph.view',
-          slot: Slots.contextPanel,
-          title: 'Graph',
-          titleKey: 'tab.graph',
-          i18nNamespace: id,
-          priority: -80,
-          build: (_) => const GraphView(),
-        ),
-      ];
+  List<ContributionPoint> get contributions => const [];
 }

lib/builtin/markdown/src/extension.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:clide/builtin/markdown/src/markdown_viewer.dart';
 import 'package:clide/extension/extension.dart';
 import 'package:clide/kernel/kernel.dart';
@@ -8,20 +10,51 @@ class MarkdownExtension extends ClideExtension {
   @override
   String get title => 'Markdown';
   @override
-  String get version => '0.1.0';
+  String get version => '0.2.0';
   @override
   List<String> get dependsOn => const ['builtin.editor'];
 
+  ClideExtensionContext? _ctx;
+  StreamSubscription<DaemonEvent>? _editorSub;
+  bool _viewerSpawned = false;
+
   @override
-  List<ContributionPoint> get contributions => [
-        TabContribution(
-          id: 'markdown.viewer',
-          slot: Slots.contextPanel,
-          title: 'Viewer',
-          titleKey: 'tab.viewer',
-          i18nNamespace: id,
-          priority: -100,
-          build: (_) => const MarkdownViewer(),
-        ),
-      ];
+  List<ContributionPoint> get contributions => const [];
+
+  @override
+  Future<void> activate(ClideExtensionContext ctx) async {
+    _ctx = ctx;
+    _editorSub = ctx.events.on<DaemonEvent>().listen((e) {
+      if (e.subsystem != 'editor') return;
+      if (e.kind == 'editor.active-changed' || e.kind == 'editor.opened') {
+        final path = e.data['path'] as String?;
+        if (path != null && path.endsWith('.md')) {
+          _spawnViewer();
+        }
+      }
+    });
+  }
+
+  @override
+  Future<void> deactivate() async {
+    _editorSub?.cancel();
+    if (_viewerSpawned) {
+      _ctx?.panels.uncontribute('markdown.viewer');
+      _viewerSpawned = false;
+    }
+  }
+
+  void _spawnViewer() {
+    final ctx = _ctx;
+    if (ctx == null || _viewerSpawned) return;
+    ctx.panels.contribute(TabContribution(
+      id: 'markdown.viewer',
+      slot: Slots.contextPanel,
+      title: 'Viewer',
+      priority: -100,
+      build: (_) => const MarkdownViewer(),
+    ));
+    _viewerSpawned = true;
+    ctx.panels.activateTab(Slots.contextPanel, 'markdown.viewer');
+  }
 }

lib/builtin/pql/src/extension.dart

@@ -1,3 +1,5 @@
+import 'dart:async';
+
 import 'package:clide/builtin/pql/src/backlinks_view.dart';
 import 'package:clide/builtin/pql/src/pql_panel_view.dart';
 import 'package:clide/extension/extension.dart';
@@ -9,10 +11,14 @@ class PqlExtension extends ClideExtension {
   @override
   String get title => 'pql';
   @override
-  String get version => '0.1.0';
+  String get version => '0.2.0';
   @override
   List<String> get dependsOn => const [];
 
+  ClideExtensionContext? _ctx;
+  StreamSubscription<DaemonEvent>? _editorSub;
+  bool _backlinksSpawned = false;
+
   @override
   List<ContributionPoint> get contributions => [
         TabContribution(
@@ -24,14 +30,43 @@ class PqlExtension extends ClideExtension {
           priority: -60,
           build: (_) => const PqlPanelView(),
         ),
-        TabContribution(
-          id: 'pql.backlinks',
-          slot: Slots.contextPanel,
-          title: 'Links',
-          titleKey: 'tab.links',
-          i18nNamespace: id,
-          priority: -80,
-          build: (_) => const BacklinksView(),
-        ),
       ];
+
+  @override
+  Future<void> activate(ClideExtensionContext ctx) async {
+    _ctx = ctx;
+    _editorSub = ctx.events.on<DaemonEvent>().listen((e) {
+      if (e.subsystem != 'editor') return;
+      if (e.kind == 'editor.active-changed' || e.kind == 'editor.opened') {
+        _spawnBacklinks();
+      }
+    });
+  }
+
+  @override
+  Future<void> deactivate() async {
+    _editorSub?.cancel();
+    _despawnBacklinks();
+  }
+
+  void _spawnBacklinks() {
+    final ctx = _ctx;
+    if (ctx == null || _backlinksSpawned) return;
+    ctx.panels.contribute(TabContribution(
+      id: 'pql.backlinks',
+      slot: Slots.contextPanel,
+      title: 'Links',
+      priority: -80,
+      build: (_) => const BacklinksView(),
+    ));
+    _backlinksSpawned = true;
+    ctx.panels.activateTab(Slots.contextPanel, 'pql.backlinks');
+  }
+
+  void _despawnBacklinks() {
+    if (_backlinksSpawned) {
+      _ctx?.panels.uncontribute('pql.backlinks');
+      _backlinksSpawned = false;
+    }
+  }
 }

lib/builtin/tickets/src/extension.dart

@@ -1,7 +1,10 @@
+import 'dart:async';
+
 import 'package:clide/builtin/tickets/src/ticket_detail_view.dart';
 import 'package:clide/builtin/tickets/src/tickets_view.dart';
 import 'package:clide/extension/extension.dart';
 import 'package:clide/kernel/kernel.dart';
+import 'package:clide/kernel/src/events/message_bus.dart';
 
 class TicketsExtension extends ClideExtension {
   @override
@@ -9,10 +12,14 @@ class TicketsExtension extends ClideExtension {
   @override
   String get title => 'Tickets';
   @override
-  String get version => '0.2.0';
+  String get version => '0.3.0';
   @override
   List<String> get dependsOn => const [];
 
+  ClideExtensionContext? _ctx;
+  StreamSubscription<Message>? _selectionSub;
+  bool _detailSpawned = false;
+
   @override
   List<ContributionPoint> get contributions => [
         TabContribution(
@@ -24,12 +31,40 @@ class TicketsExtension extends ClideExtension {
           priority: -10,
           build: (_) => const TicketsView(),
         ),
-        TabContribution(
-          id: 'tickets.detail',
-          slot: Slots.contextPanel,
-          title: 'Ticket',
-          priority: -60,
-          build: (_) => const TicketDetailView(),
-        ),
       ];
+
+  @override
+  Future<void> activate(ClideExtensionContext ctx) async {
+    _ctx = ctx;
+    _selectionSub = ctx.messages.subscribe(publisher: id, channel: 'selection').listen(_onSelection);
+  }
+
+  @override
+  Future<void> deactivate() async {
+    _selectionSub?.cancel();
+    _despawnDetail();
+  }
+
+  void _onSelection(Message msg) {
+    final ctx = _ctx;
+    if (ctx == null) return;
+    if (!_detailSpawned) {
+      ctx.panels.contribute(TabContribution(
+        id: 'tickets.detail',
+        slot: Slots.contextPanel,
+        title: 'Ticket',
+        priority: -60,
+        build: (_) => const TicketDetailView(),
+      ));
+      _detailSpawned = true;
+    }
+    ctx.panels.activateTab(Slots.contextPanel, 'tickets.detail');
+  }
+
+  void _despawnDetail() {
+    if (_detailSpawned) {
+      _ctx?.panels.uncontribute('tickets.detail');
+      _detailSpawned = false;
+    }
+  }
 }