fix(app): open new tabs in the focused pane

Preserve ambient placement for reconciliation and background opens while routing user-directed tab creation through the focused visible pane. Defer terminal reconciliation during creates so a push cannot preempt the intended pane placement.

packages/app/src/stores/workspace-layout-actions.ts

@@ -213,6 +213,7 @@ export interface WorkspaceTabSnapshot {
   knownAgentIds: Iterable<string>;
   knownTerminalIds?: Iterable<string>;
   standaloneTerminalIds: Iterable<string>;
+  hasActivePendingTerminalCreate?: boolean;
   hasActivePendingDraftCreate?: boolean;
 }
 
@@ -1866,6 +1867,7 @@ function addMissingEntityTabs(input: {
   autoOpenAgentIds: Set<string>;
   representedAgentIds: Set<string>;
   standaloneTerminalIds: Set<string>;
+  hasActivePendingTerminalCreate: boolean;
   hasActivePendingDraftCreate: boolean;
   explorerPaneId: string | null;
 }): WorkspaceLayout {
@@ -1873,6 +1875,7 @@ function addMissingEntityTabs(input: {
     autoOpenAgentIds,
     representedAgentIds,
     standaloneTerminalIds,
+    hasActivePendingTerminalCreate,
     hasActivePendingDraftCreate,
     explorerPaneId,
   } = input;
@@ -1902,16 +1905,18 @@ function addMissingEntityTabs(input: {
   }
 
   const sortedTerminalIds = [...standaloneTerminalIds].sort();
-  for (const terminalId of sortedTerminalIds) {
-    if (currentTerminalIds.has(terminalId)) {
-      continue;
+  if (!hasActivePendingTerminalCreate) {
+    for (const terminalId of sortedTerminalIds) {
+      if (currentTerminalIds.has(terminalId)) {
+        continue;
+      }
+      nextLayout = openEntityTabWithoutFocusing({
+        layout: nextLayout,
+        target: { kind: "terminal", terminalId },
+        explorerPaneId,
+      });
+      currentTerminalIds.add(terminalId);
     }
-    nextLayout = openEntityTabWithoutFocusing({
-      layout: nextLayout,
-      target: { kind: "terminal", terminalId },
-      explorerPaneId,
-    });
-    currentTerminalIds.add(terminalId);
   }
   return nextLayout;
 }
@@ -1999,6 +2004,7 @@ export function reconcileWorkspaceTabs(
     autoOpenAgentIds: autoOpenSet,
     representedAgentIds,
     standaloneTerminalIds,
+    hasActivePendingTerminalCreate: snapshot.hasActivePendingTerminalCreate ?? false,
     hasActivePendingDraftCreate: snapshot.hasActivePendingDraftCreate ?? false,
     explorerPaneId: state.explorerPaneId,
   });

packages/app/src/stores/workspace-layout-store.test.ts

@@ -585,6 +585,35 @@ describe("workspace-layout-store actions", () => {
     expect(layout.focusedPaneId).toBe("explorer");
   });
 
+  it("keeps ambient browser opens out of the focused explorer pane", () => {
+    const workspaceKey = createWorkspaceKey();
+    const store = workspaceLayoutStore.getState();
+    store.openTabFocused(workspaceKey, { kind: "browser", browserId: "browser-1" });
+    store.focusPane(workspaceKey, "explorer");
+
+    const browserTabId = store.openTabFocused(workspaceKey, {
+      kind: "browser",
+      browserId: "browser-2",
+    });
+
+    const layout = workspaceLayoutStore.getState().layoutByWorkspace[workspaceKey];
+    expect(findPaneContainingTab(layout.root, browserTabId as string)?.id).toBe("main");
+    expect(layout.focusedPaneId).toBe("main");
+  });
+
+  it("keeps ambient draft opens out of the focused explorer pane", () => {
+    const workspaceKey = createWorkspaceKey();
+    const store = workspaceLayoutStore.getState();
+    store.openTabFocused(workspaceKey, { kind: "agent", agentId: "agent-1" });
+    store.focusPane(workspaceKey, "explorer");
+
+    const draftTabId = store.openTabFocused(workspaceKey, { kind: "draft", draftId: "draft-1" });
+
+    const layout = workspaceLayoutStore.getState().layoutByWorkspace[workspaceKey];
+    expect(findPaneContainingTab(layout.root, draftTabId as string)?.id).toBe("main");
+    expect(layout.focusedPaneId).toBe("main");
+  });
+
   it("honours an explicit pane id over the explorer reroute", () => {
     const workspaceKey = createWorkspaceKey();
     const store = workspaceLayoutStore.getState();
@@ -601,6 +630,76 @@ describe("workspace-layout-store actions", () => {
     expect(layout.focusedPaneId).toBe("explorer");
   });
 
+  it("opens user-created entity tabs in the focused explorer pane", () => {
+    const workspaceKey = createWorkspaceKey();
+    const store = workspaceLayoutStore.getState();
+    store.openTabFocused(workspaceKey, { kind: "agent", agentId: "agent-1" });
+    store.focusPane(workspaceKey, "explorer");
+
+    const terminalTabId = store.openTabInFocusedPane(workspaceKey, {
+      kind: "terminal",
+      terminalId: "terminal-1",
+    });
+
+    const layout = workspaceLayoutStore.getState().layoutByWorkspace[workspaceKey];
+    expect(findPaneContainingTab(layout.root, terminalTabId as string)?.id).toBe("explorer");
+    expect(layout.focusedPaneId).toBe("explorer");
+  });
+
+  it("keeps an existing user-created entity tab in its original pane", () => {
+    const workspaceKey = createWorkspaceKey();
+    const store = workspaceLayoutStore.getState();
+    const terminalTabId = store.openTabInBackground(workspaceKey, {
+      kind: "terminal",
+      terminalId: "terminal-1",
+    });
+    store.showPane(workspaceKey, "explorer");
+    store.focusPane(workspaceKey, "explorer");
+
+    store.openTabInFocusedPane(workspaceKey, {
+      kind: "terminal",
+      terminalId: "terminal-1",
+    });
+
+    const layout = workspaceLayoutStore.getState().layoutByWorkspace[workspaceKey];
+    expect(findPaneContainingTab(layout.root, terminalTabId as string)?.id).toBe("main");
+    expect(findPaneById(layout.root, "main")).toBeTruthy();
+    expect(layout.focusedPaneId).toBe("main");
+  });
+
+  it("defers terminal reconciliation while a user terminal is being created", () => {
+    const workspaceKey = createWorkspaceKey();
+    const store = workspaceLayoutStore.getState();
+    store.focusPane(workspaceKey, "explorer");
+
+    store.reconcileTabs(workspaceKey, {
+      agentsHydrated: true,
+      terminalsHydrated: true,
+      activeAgentIds: [],
+      autoOpenAgentIds: [],
+      knownAgentIds: [],
+      knownTerminalIds: ["terminal-1"],
+      standaloneTerminalIds: ["terminal-1"],
+      hasActivePendingTerminalCreate: true,
+    });
+
+    let layout = workspaceLayoutStore.getState().layoutByWorkspace[workspaceKey];
+    expect(findPaneContainingTab(layout.root, "terminal_terminal-1")).toBeNull();
+
+    store.reconcileTabs(workspaceKey, {
+      agentsHydrated: true,
+      terminalsHydrated: true,
+      activeAgentIds: [],
+      autoOpenAgentIds: [],
+      knownAgentIds: [],
+      knownTerminalIds: ["terminal-1"],
+      standaloneTerminalIds: ["terminal-1"],
+    });
+
+    layout = workspaceLayoutStore.getState().layoutByWorkspace[workspaceKey];
+    expect(findPaneContainingTab(layout.root, "terminal_terminal-1")?.id).toBe("main");
+  });
+
   it("keeps non-entity tabs in the focused explorer pane", () => {
     const workspaceKey = createWorkspaceKey();
     const store = workspaceLayoutStore.getState();

packages/app/src/stores/workspace-layout-store.ts

@@ -86,12 +86,18 @@ interface WorkspaceLayoutStore {
     target: WorkspaceTabTarget,
     options?: WorkspaceTabOpenOptions,
   ) => string | null;
+  openTabInFocusedPane: (workspaceKey: string, target: WorkspaceTabTarget) => string | null;
   openChildTabFocused: (
     workspaceKey: string,
     target: WorkspaceTabTarget,
     parentTabId: string,
     options?: WorkspaceTabOpenOptions,
   ) => string | null;
+  openChildTabInFocusedPane: (
+    workspaceKey: string,
+    target: WorkspaceTabTarget,
+    parentTabId: string,
+  ) => string | null;
   openTabInBackground: (
     workspaceKey: string,
     target: WorkspaceTabTarget,
@@ -146,11 +152,7 @@ interface WorkspaceLayoutStore {
   purgeWorkspace: (workspaceKey: string) => void;
 }
 
-/**
- * `paneId` states which pane the user acted in — the `+` menu of a pane's tab rail,
- * a subagent link inside a pane. Without it the open is ambient (sidebar click,
- * reconcile auto-open) and the store decides the pane.
- */
+/** `paneId` is explicit placement for a pane-local affordance; omitted opens use policy. */
 export interface WorkspaceTabOpenOptions {
   paneId?: string | null;
 }
@@ -463,6 +465,17 @@ export function createWorkspaceLayoutStore(
 
           return result.tabId;
         },
+        openTabInFocusedPane: (workspaceKey, target) => {
+          const normalizedWorkspaceKey = trimNonEmpty(workspaceKey);
+          if (!normalizedWorkspaceKey) {
+            return null;
+          }
+          const layout = getWorkspaceLayout(get().layoutByWorkspace, normalizedWorkspaceKey);
+          const focusedPane = findPaneById(layout.root, layout.focusedPaneId);
+          return get().openTabFocused(normalizedWorkspaceKey, target, {
+            paneId: focusedPane?.hidden === true ? null : focusedPane?.id,
+          });
+        },
         openChildTabFocused: (workspaceKey, target, parentTabId, options) => {
           const normalizedWorkspaceKey = trimNonEmpty(workspaceKey);
           const normalizedParentTabId = trimNonEmpty(parentTabId);
@@ -502,6 +515,17 @@ export function createWorkspaceLayoutStore(
 
           return result.tabId;
         },
+        openChildTabInFocusedPane: (workspaceKey, target, parentTabId) => {
+          const normalizedWorkspaceKey = trimNonEmpty(workspaceKey);
+          if (!normalizedWorkspaceKey) {
+            return null;
+          }
+          const layout = getWorkspaceLayout(get().layoutByWorkspace, normalizedWorkspaceKey);
+          const focusedPane = findPaneById(layout.root, layout.focusedPaneId);
+          return get().openChildTabFocused(normalizedWorkspaceKey, target, parentTabId, {
+            paneId: focusedPane?.hidden === true ? null : focusedPane?.id,
+          });
+        },
         openTabInBackground: (workspaceKey, target, options) => {
           const normalizedWorkspaceKey = trimNonEmpty(workspaceKey);
           const normalizedTarget = normalizeWorkspaceTabTarget(target);

packages/app/src/stores/workspace-subagents-integration.test.ts

@@ -108,6 +108,7 @@ function reconcileWorkspaceTabs(workspaceKey: string, visibility: WorkspaceAgent
       terminalsHydrated: true,
       knownTerminalIds: [],
       standaloneTerminalIds: [],
+      hasActivePendingTerminalCreate: false,
       hasActivePendingDraftCreate: false,
     }),
   );