feat: allow multiple terminal tabs per connection

docs/superpowers/plans/2026-03-26-terminal-multi-tabs.md

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+# Terminal Multi Tabs Implementation Plan
+
+> **For agentic workers:** REQUIRED: Use superpowers:subagent-driven-development (if subagents available) or superpowers:executing-plans to implement this plan. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Allow the connection list to open multiple terminal tabs for the same connection, with each click creating a fresh terminal session.
+
+**Architecture:** Keep the existing `/terminal` workspace and Pinia-driven tab model, but change terminal tab creation from connection-deduplicated to always-new. Add lightweight title numbering so repeated tabs for the same connection remain distinguishable without changing routing or terminal widget lifecycle.
+
+**Tech Stack:** Vue 3, TypeScript, Pinia, Vue Router, xterm.js, Vite, vue-tsc
+
+---
+
+## File Structure
+
+- Modify: `frontend/src/stores/terminalTabs.ts`
+  - Change tab creation semantics and add repeated-title numbering.
+- Modify: `frontend/src/views/ConnectionsView.vue`
+  - Use the new always-open terminal action from the connection list.
+- Verify: `frontend/src/views/TerminalWorkspaceView.vue`
+  - Confirm current per-tab widget mounting already supports independent sessions.
+- Verify: `frontend/src/layouts/MainLayout.vue`
+  - Confirm terminal sidebar tab rendering needs no structure change beyond new titles.
+- Reference: `docs/superpowers/specs/2026-03-26-terminal-multi-tabs-design.md`
+  - Source of truth for behavior and acceptance criteria.
+
+### Task 1: Change Terminal Tabs Store to Always Create New Tabs
+
+**Files:**
+- Modify: `frontend/src/stores/terminalTabs.ts`
+- Reference: `frontend/src/stores/sftpTabs.ts`
+
+- [ ] **Step 1: Inspect current tab store behavior**
+
+Read `frontend/src/stores/terminalTabs.ts` and confirm the existing dedup-by-connection behavior.
+
+- [ ] **Step 2: Add repeated-title generation**
+
+Add a helper that counts currently open tabs for the same `connectionId` and returns:
+
+```ts
+function getTabTitle(connection: Connection) {
+  const sameConnectionCount = tabs.value.filter(t => t.connectionId === connection.id).length
+
+  if (sameConnectionCount === 0) {
+    return connection.name
+  }
+
+  return `${connection.name} (${sameConnectionCount + 1})`
+}
+```
+
+- [ ] **Step 3: Replace dedup open logic with always-new creation**
+
+Change the open action so it always creates a new `TerminalTab` and activates it immediately.
+
+- [ ] **Step 4: Keep activate/close behavior unchanged**
+
+Do not change tab activation and close-neighbor behavior except what is necessary to support the new open logic.
+
+### Task 2: Wire the Connection List to the New Behavior
+
+**Files:**
+- Modify: `frontend/src/views/ConnectionsView.vue`
+- Use: `frontend/src/stores/terminalTabs.ts`
+
+- [ ] **Step 1: Rename the method usage to match semantics**
+
+Update `openTerminal(conn)` to call the new always-open store action.
+
+- [ ] **Step 2: Preserve routing behavior**
+
+Keep `router.push('/terminal')` unchanged after opening the tab.
+
+### Task 3: Verify Integration and Build
+
+**Files:**
+- Verify: `frontend/src/layouts/MainLayout.vue`
+- Verify: `frontend/src/views/TerminalWorkspaceView.vue`
+
+- [ ] **Step 1: Confirm sidebar rendering already keys by `tab.id`**
+
+No structural code changes should be required if repeated tabs render correctly with distinct titles.
+
+- [ ] **Step 2: Run final frontend build**
+
+Run in `frontend/`:
+
+```bash
+npm run build
+```
+
+Expected: `vue-tsc -b` and `vite build` both pass.
+
+- [ ] **Step 3: Manual runtime verification**
+
+Check:
+
+1. Same connection opens multiple terminal tabs.
+2. Repeated tabs are titled distinctly.
+3. Each tab remains an independent terminal session.
+4. Close/switch behavior still works.

docs/superpowers/specs/2026-03-26-terminal-multi-tabs-design.md

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+# 2026-03-26 Terminal Multi Tabs Design
+
+## Background
+
+The connection list already opens terminal sessions into the shared terminal workspace at `/terminal`, and the sidebar already renders terminal tabs. However, the current store deduplicates tabs by `connectionId`, so clicking `终端` for the same connection only focuses the existing tab instead of opening a new shell session.
+
+## Goal
+
+- Allow users to open multiple terminal tabs from the connection list for the same connection.
+- Keep each terminal tab as an independent shell session.
+- Preserve the current terminal workspace route and sidebar interaction model.
+
+## Non-Goals
+
+- No tab persistence across refresh.
+- No route change from `/terminal` to per-tab URLs.
+- No generic tab-system refactor shared with SFTP.
+- No terminal session restore or reconnect workflow.
+
+## Current State
+
+- `frontend/src/stores/terminalTabs.ts` manages terminal tabs.
+- `openOrFocus(connection)` reuses an existing tab when `connectionId` matches.
+- `frontend/src/views/ConnectionsView.vue` uses that method before routing to `/terminal`.
+- `frontend/src/views/TerminalWorkspaceView.vue` already mounts one `TerminalWidget` per tab keyed by `tab.id`, so multiple tabs can coexist as long as the store allows them.
+
+## Selected Approach
+
+Keep the existing terminal workspace architecture and change only the terminal tab creation semantics: clicking `终端` always creates a new tab, even when the same connection already has open tabs.
+
+### 1. Terminal tab creation becomes always-new
+
+Update `frontend/src/stores/terminalTabs.ts` so the terminal action always creates a new tab entry:
+
+- remove the `connectionId` dedup behavior from the open action
+- generate a fresh `tab.id` every time
+- activate the newly created tab immediately
+
+This preserves the current in-memory tab lifecycle while enabling multiple concurrent sessions to the same host.
+
+### 2. Distinguishable tab titles for repeated connections
+
+When the same connection is opened multiple times, sidebar labels must remain distinguishable.
+
+Recommended title strategy:
+
+- first tab: `Connection Name`
+- second tab: `Connection Name (2)`
+- third tab: `Connection Name (3)`
+
+The sequence is computed from currently open tabs for the same `connectionId`. No persistence is needed.
+
+### 3. Connections entry behavior
+
+Update `frontend/src/views/ConnectionsView.vue` so clicking `终端` calls the always-new tab action and routes to `/terminal`.
+
+Result:
+
+- each click from the connection list opens a fresh shell session
+- users can intentionally keep several terminals open for the same host
+
+### 4. Terminal workspace behavior stays unchanged
+
+`frontend/src/views/TerminalWorkspaceView.vue` and `frontend/src/components/TerminalWidget.vue` do not need architectural changes:
+
+- the workspace already loops through tabs by `tab.id`
+- each active tab renders its own `TerminalWidget`
+- each widget maintains an independent xterm instance and WebSocket connection
+
+This matches the desired UX: multiple tabs for the same connection are separate terminal sessions rather than alternate views of one shared session.
+
+## Behavior Kept Unchanged
+
+- Terminal route remains `/terminal`.
+- Sidebar terminal tab section remains the primary tab switcher.
+- Closing and activating adjacent terminal tabs continues to follow the current logic.
+- SFTP tab behavior remains unchanged.
+- Existing slate/cyan visual language remains unchanged.
+
+## Acceptance Criteria
+
+- Clicking `终端` for the same connection multiple times creates multiple terminal tabs.
+- Each new terminal tab becomes the active tab.
+- Repeated tabs for the same connection are visually distinguishable in the sidebar.
+- Switching between tabs preserves each tab's own terminal session output.
+- Closing a terminal tab keeps current close/activate behavior intact.
+- Opening tabs for different connections continues to work.
+
+## Verification
+
+- Run `npm run build` in `frontend/`.
+- Manual verification:
+  1. Click `终端` on the same connection three times and confirm three tabs appear.
+  2. Confirm the sidebar shows distinguishable titles for repeated tabs.
+  3. Type different commands in different tabs for the same connection and confirm each tab keeps its own output.
+  4. Close active and inactive terminal tabs and confirm focus changes remain correct.
+  5. Re-check that opening terminal tabs for different connections still works.