fix(ai): keep dissolved workspace chat on its surviving owner

Detach-drag focuses the dragged pane, so dissolve handoff treated the
undragged pane as preferred and reminted an inherited terminal chat onto
it. Keep that chat on its owner when the owner still survives.

Co-authored-by: 陈大猫 <binaricat@users.noreply.github.com>

domain/workspaceAiScopeHandoff.test.ts

@@ -108,7 +108,7 @@ test('handoffDissolvedWorkspaceAIScope retargets inherited chat when its pane is
   });
 });
 
-test('handoffDissolvedWorkspaceAIScope retargets inherited chat when original pane also survives', () => {
+test('handoffDissolvedWorkspaceAIScope keeps inherited chat on its surviving owner pane', () => {
   const result = handoffDissolvedWorkspaceAIScope({
     activeSessionIdMap: {
       'workspace:ws-1': 'chat-a',
@@ -132,12 +132,52 @@ test('handoffDissolvedWorkspaceAIScope retargets inherited chat when original pa
     preferredTerminalId: 'term-b',
   });
 
-  assert.equal(result.changed, true);
-  assert.equal(result.activeSessionIdMap['terminal:term-b'], 'chat-a');
-  assert.equal(result.activeSessionIdMap['terminal:term-a'], null);
-  assert.equal(result.sessions[0]?.scope.targetId, 'term-b');
+  assert.equal(result.activeSessionIdMap['terminal:term-a'], 'chat-a');
+  assert.equal(result.activeSessionIdMap['terminal:term-b'], 'chat-b');
+  assert.equal(result.sessions[0]?.scope.type, 'terminal');
+  assert.equal(result.sessions[0]?.scope.targetId, 'term-a');
+  assert.equal(result.sessions[0]?.updatedAt, 1);
   assert.equal(result.sessions[1]?.scope.targetId, 'term-b');
-  assert.deepEqual(result.panelViewByScope['terminal:term-b'], {
+  assert.deepEqual(result.panelViewByScope['terminal:term-a'], {
+    mode: 'session',
+    sessionId: 'chat-a',
+  });
+  assert.equal(result.panelViewByScope['terminal:term-b'], undefined);
+});
+
+test('handoffDissolvedWorkspaceAIScope keeps owner history when the other pane is preferred', () => {
+  const result = handoffDissolvedWorkspaceAIScope({
+    activeSessionIdMap: {
+      'workspace:ws-1': 'chat-a',
+      'terminal:term-b': 'chat-b',
+    },
+    sessions: [
+      {
+        id: 'chat-a',
+        scope: { type: 'terminal', targetId: 'term-a', hostIds: ['host-a'] },
+        updatedAt: 1,
+      },
+      {
+        id: 'chat-b',
+        scope: { type: 'terminal', targetId: 'term-b', hostIds: ['host-b'] },
+        updatedAt: 1,
+      },
+    ],
+    workspaceId: 'ws-1',
+    terminalIds: ['term-a', 'term-b'],
+    preferredTerminalId: 'term-b',
+    panelViewByScope: {
+      'workspace:ws-1': { mode: 'session', sessionId: 'chat-a' },
+    },
+  });
+
+  assert.equal(result.changed, true);
+  assert.equal(result.activeSessionIdMap['terminal:term-a'], 'chat-a');
+  assert.equal(result.activeSessionIdMap['terminal:term-b'], 'chat-b');
+  assert.equal(result.sessions[0]?.scope.targetId, 'term-a');
+  assert.equal(result.sessions[1]?.id, 'chat-b');
+  assert.equal(result.sessions[1]?.scope.targetId, 'term-b');
+  assert.deepEqual(result.panelViewByScope['terminal:term-a'], {
     mode: 'session',
     sessionId: 'chat-a',
   });

domain/workspaceAiScopeHandoff.ts

@@ -78,13 +78,15 @@ export function seedWorkspaceAIActiveSessionFromMembers(input: {
 }
 
 /**
- * When a workspace tab dissolves, copy its active chat onto the preferred
- * surviving terminal before the workspace scope key is pruned. Also remint
- * workspace-scoped chats and the handed-off active chat when it still lives
- * under a different terminal (including one that also survives dissolve),
- * clear that previous terminal selection so ownership filters do not hide the
- * chat, and seed a session panel view so terminal scopes do not fall back to
- * a blank draft.
+ * When a workspace tab dissolves, copy its active chat onto a surviving
+ * terminal before the workspace scope key is pruned. An inherited chat that
+ * is already terminal-scoped to a pane still in `terminalIds` stays on that
+ * owner, even when focus/preferred is a different survivor. Otherwise the
+ * target is the preferred survivor, or the first remaining terminal when the
+ * original pane is gone. Workspace-scoped chats are reminted onto that
+ * target, duplicate terminal map entries for the same chat are cleared, and
+ * a session panel view is seeded so terminal scopes do not fall back to a
+ * blank draft.
  */
 export function handoffDissolvedWorkspaceAIScope<T extends AISessionScopeHandoffLike>(input: {
   activeSessionIdMap: AIActiveSessionIdMap;
@@ -99,7 +101,7 @@ export function handoffDissolvedWorkspaceAIScope<T extends AISessionScopeHandoff
   panelViewByScope: Record<string, AIPanelViewHandoffLike>;
   changed: boolean;
 } {
-  const preferredTerminalId = (
+  const fallbackTerminalId = (
     input.preferredTerminalId
     && input.terminalIds.includes(input.preferredTerminalId)
       ? input.preferredTerminalId
@@ -109,6 +111,17 @@ export function handoffDissolvedWorkspaceAIScope<T extends AISessionScopeHandoff
   const workspaceKey = buildAIScopeKey('workspace', input.workspaceId);
   const workspaceActive = input.activeSessionIdMap[workspaceKey];
   const hasWorkspaceActive = typeof workspaceActive === 'string' && workspaceActive.length > 0;
+  const activeSession = hasWorkspaceActive
+    ? input.sessions.find((session) => session.id === workspaceActive)
+    : undefined;
+  const survivingOwnerTerminalId = (
+    activeSession?.scope.type === 'terminal'
+    && activeSession.scope.targetId
+    && input.terminalIds.includes(activeSession.scope.targetId)
+      ? activeSession.scope.targetId
+      : null
+  );
+  const handoffTargetTerminalId = survivingOwnerTerminalId ?? fallbackTerminalId;
   const previousPanelViewByScope = (
     input.panelViewByScope as Record<string, AIPanelViewHandoffLike> | undefined
   ) ?? {};
@@ -118,8 +131,8 @@ export function handoffDissolvedWorkspaceAIScope<T extends AISessionScopeHandoff
   };
   let mapChanged = false;
 
-  if (preferredTerminalId && hasWorkspaceActive) {
-    const terminalKey = buildAIScopeKey('terminal', preferredTerminalId);
+  if (handoffTargetTerminalId && hasWorkspaceActive) {
+    const terminalKey = buildAIScopeKey('terminal', handoffTargetTerminalId);
     let map = nextMap;
     let changed = false;
     if (map[terminalKey] !== workspaceActive) {
@@ -145,24 +158,23 @@ export function handoffDissolvedWorkspaceAIScope<T extends AISessionScopeHandoff
 
   let sessionsChanged = false;
   const nextSessions = input.sessions.map((session) => {
-    if (!preferredTerminalId) return session;
+    if (!handoffTargetTerminalId) return session;
 
     const isWorkspaceScoped = (
       session.scope.type === 'workspace'
       && session.scope.targetId === input.workspaceId
     );
-    // Inherited member chats stay terminal-scoped under the original pane.
-    // Prefer the focused survivor even when that original pane also survives
-    // dissolve, otherwise B's history ownership filter excludes A's chat.
+    // Keep an inherited chat on its owner when that pane survives. Remint
+    // only when the handoff target is a different terminal (original pane gone).
     const isInheritedActiveChatOnOtherTerminal = (
       hasWorkspaceActive
       && session.id === workspaceActive
       && session.scope.type === 'terminal'
       && Boolean(session.scope.targetId)
-      && session.scope.targetId !== preferredTerminalId
+      && session.scope.targetId !== handoffTargetTerminalId
     );
     if (!isWorkspaceScoped && !isInheritedActiveChatOnOtherTerminal) return session;
-    if (session.scope.type === 'terminal' && session.scope.targetId === preferredTerminalId) {
+    if (session.scope.type === 'terminal' && session.scope.targetId === handoffTargetTerminalId) {
       return session;
     }
 
@@ -172,7 +184,7 @@ export function handoffDissolvedWorkspaceAIScope<T extends AISessionScopeHandoff
       scope: {
         ...session.scope,
         type: 'terminal',
-        targetId: preferredTerminalId,
+        targetId: handoffTargetTerminalId,
       },
       updatedAt: Date.now(),
     };
@@ -182,8 +194,8 @@ export function handoffDissolvedWorkspaceAIScope<T extends AISessionScopeHandoff
   const nextPanelViewByScope: Record<string, AIPanelViewHandoffLike> = {
     ...previousPanelViewByScope,
   };
-  if (preferredTerminalId && hasWorkspaceActive) {
-    const terminalKey = buildAIScopeKey('terminal', preferredTerminalId);
+  if (handoffTargetTerminalId && hasWorkspaceActive) {
+    const terminalKey = buildAIScopeKey('terminal', handoffTargetTerminalId);
     const workspacePanelView = previousPanelViewByScope[workspaceKey];
     const terminalPanelView = previousPanelViewByScope[terminalKey];
     const nextView: AIPanelViewHandoffLike = (