fix(app): navigate tabs by selection history

packages/app/src/components/titlebar.tsx

@@ -419,33 +419,15 @@ export function Titlebar(props: { update?: TitlebarUpdate; debugTools?: { visibl
                   title: "",
                   keybind: `mod+option+ArrowLeft,ctrl+shift+tab`,
                   hidden: true,
-                  onSelect: () => {
-                    let index = tabsStore.findIndex((tab) => tab === currentTab())
-                    if (index === -1) return
-
-                    index -= 1
-                    if (index === -1) index = tabsStore.length - 1
-
-                    const next = tabsStore[index]
-                    if (next) tabs.select(next)
-                  },
+                  onSelect: tabs.previous,
                 },
                 {
                   id: `tab.next`,
                   category: "tab",
                   title: "",
                   keybind: `mod+option+ArrowRight,ctrl+tab`,
                   hidden: true,
-                  onSelect: () => {
-                    let index = tabsStore.findIndex((tab) => tab === currentTab())
-                    if (index === -1) return
-
-                    index += 1
-                    if (index === tabsStore.length) index = 0
-
-                    const next = tabsStore[index]
-                    if (next) tabs.select(next)
-                  },
+                  onSelect: tabs.next,
                 },
               ].filter((v) => v !== undefined)
             })

packages/app/src/context/tab-history.test.ts

@@ -0,0 +1,43 @@
+import { describe, expect, test } from "bun:test"
+import { nextTab, previousTab, rememberTab, type TabHistory } from "./tab-history"
+
+function history(): TabHistory {
+  return { stack: [], index: -1 }
+}
+
+describe("tab history", () => {
+  test("moves backward and forward through selected tabs", () => {
+    const selected = ["a", "b", "c"].reduce(rememberTab, history())
+    const available = new Set(selected.stack)
+
+    const previous = previousTab(selected, available)
+    expect(previous?.key).toBe("b")
+
+    const first = previousTab(previous!.state, available)
+    expect(first?.key).toBe("a")
+
+    const next = nextTab(first!.state, available)
+    expect(next?.key).toBe("b")
+  })
+
+  test("replaces forward history after a new selection", () => {
+    const selected = ["a", "b", "c"].reduce(rememberTab, history())
+    const previous = previousTab(selected, new Set(selected.stack))
+    const next = rememberTab(previous!.state, "d")
+
+    expect(next).toEqual({ stack: ["a", "b", "d"], index: 2 })
+    expect(nextTab(next, new Set(next.stack))).toBeUndefined()
+  })
+
+  test("skips tabs that are no longer open", () => {
+    const selected = ["a", "b", "c"].reduce(rememberTab, history())
+
+    expect(previousTab(selected, new Set(["a", "c"]))?.key).toBe("a")
+  })
+
+  test("skips a repeated current tab after closing the previous selection", () => {
+    const selected = ["a", "b", "c", "b"].reduce(rememberTab, history())
+
+    expect(previousTab(selected, new Set(["a", "b"]))?.key).toBe("a")
+  })
+})

packages/app/src/context/tab-history.ts

@@ -0,0 +1,28 @@
+const MAX_TAB_HISTORY = 100
+
+export type TabHistory = {
+  stack: string[]
+  index: number
+}
+
+export function rememberTab(state: TabHistory, key: string): TabHistory {
+  if (state.stack[state.index] === key) return state
+  const stack = state.stack.slice(0, state.index + 1).concat(key).slice(-MAX_TAB_HISTORY)
+  return { stack, index: stack.length - 1 }
+}
+
+export function previousTab(state: TabHistory, available: Set<string>) {
+  return move(state, -1, available)
+}
+
+export function nextTab(state: TabHistory, available: Set<string>) {
+  return move(state, 1, available)
+}
+
+function move(state: TabHistory, offset: -1 | 1, available: Set<string>) {
+  const current = state.stack[state.index]
+  for (let index = state.index + offset; index >= 0 && index < state.stack.length; index += offset) {
+    const key = state.stack[index]
+    if (key && key !== current && available.has(key)) return { state: { ...state, index }, key }
+  }
+}

packages/app/src/context/tabs.tsx

@@ -12,6 +12,7 @@ import { sessionHref } from "@/utils/session-route"
 import { createTabMemory } from "./tab-memory"
 import { nextTabAfterClose, pushClosedTab, removeClosedTabs, takeClosedTab, type ClosedTab } from "./closed-tabs"
 import { createDraftPromptSession, type PromptModel } from "./prompt-state"
+import { nextTab, previousTab, rememberTab, type TabHistory } from "./tab-history"
 
 export type SessionTab = {
   type: "session"
@@ -79,6 +80,7 @@ export const { use: useTabs, provider: TabsProvider } = createSimpleContext({
     const memory = createTabMemory(getOwner())
 
     const closing = new Set<string>()
+    let history: TabHistory = { stack: [], index: -1 }
     let recentWrite = 0
     let recentValue: string | undefined
 
@@ -150,10 +152,21 @@ export const { use: useTabs, provider: TabsProvider } = createSimpleContext({
 
     const navigateTab = (tab: Tab) => {
       const href = tabHref(tab)
+      history = rememberTab(history, tabKey(tab))
       setRecentKey(tabKey(tab))
       navigate(href)
     }
 
+    const moveHistory = (direction: "previous" | "next") => {
+      const available = new Set(store.map(tabKey))
+      const result = direction === "previous" ? previousTab(history, available) : nextTab(history, available)
+      if (!result) return
+      const tab = store.find((item) => tabKey(item) === result.key)
+      if (!tab) return
+      history = result.state
+      navigateTab(tab)
+    }
+
     const removeTab = (index: number) => {
       const tab = store[index]
       if (!tab) return
@@ -359,8 +372,11 @@ export const { use: useTabs, provider: TabsProvider } = createSimpleContext({
       select: navigateTab,
       remember(tab: Tab) {
         const key = tabKey(tab)
+        history = rememberTab(history, key)
         if (recentKey() !== key) setRecentKey(key)
       },
+      previous: () => moveHistory("previous"),
+      next: () => moveHistory("next"),
       toggleHome(input: { home: boolean; current?: Tab }) {
         if (input.home) {
           const tab = store.find((tab) => tabKey(tab) === recentKey())

packages/app/src/desktop-menu.test.ts

@@ -2,6 +2,17 @@ import { describe, expect, test } from "bun:test"
 import { DESKTOP_MENU } from "./desktop-menu"
 
 describe("desktop menu", () => {
+  test("navigates between tabs", () => {
+    const items = DESKTOP_MENU.flatMap((menu) => menu.items ?? []).filter(
+      (item) => item.type === "item" && (item.label === "Previous Tab" || item.label === "Next Tab"),
+    )
+
+    expect(items).toEqual([
+      { type: "item", label: "Previous Tab", command: "tab.prev", accelerator: { macos: "Option+Up" } },
+      { type: "item", label: "Next Tab", command: "tab.next", accelerator: { macos: "Option+Down" } },
+    ])
+  })
+
   test("exports logs through the desktop command registry", () => {
     const items = DESKTOP_MENU.flatMap((menu) => menu.items ?? []).filter(
       (item) => item.type === "item" && item.label === "Export Logs...",

packages/app/src/desktop-menu.ts

@@ -168,8 +168,8 @@ export const DESKTOP_MENU: DesktopMenu[] = [
       { type: "item", label: "Back", command: "common.goBack", accelerator: { macos: "Cmd+[" } },
       { type: "item", label: "Forward", command: "common.goForward", accelerator: { macos: "Cmd+]" } },
       { type: "separator" },
-      { type: "item", label: "Previous Session", command: "session.previous", accelerator: { macos: "Option+Up" } },
-      { type: "item", label: "Next Session", command: "session.next", accelerator: { macos: "Option+Down" } },
+      { type: "item", label: "Previous Tab", command: "tab.prev", accelerator: { macos: "Option+Up" } },
+      { type: "item", label: "Next Tab", command: "tab.next", accelerator: { macos: "Option+Down" } },
       { type: "separator" },
       {
         type: "item",