Visual Studio Code 1.135 arrived on August 26, 2026, and this release focuses on breaking down the walls between VS Code and other AI coding tools — while also making the Agents window cleaner and giving you better visibility into what your chats actually cost.
The four headline features:
- Continue external agent sessions in VS Code — pick up Copilot or Claude sessions started in other apps
- Rubber Duck (Experimental) — get a second opinion from a complementary model on agent work
- Agents window UX improvements — single-pane side layout is now the default, with simplified session controls
- Detailed chat turn usage — per-model token breakdowns for input, cached input, and output
Let’s break down what each of these means for your daily workflow.
Continue External Agent Sessions in VS Code
This is the feature that quietly changes how you think about agent sessions. Until now, a session you started in the GitHub Copilot app, Copilot CLI, or another Claude-capable tool lived in that tool. If you wanted to continue it in VS Code — with full editor context, file changes, and the Agents window — you had to start over or copy context manually.
With 1.135, the Sessions list in VS Code can now show recent Copilot or Claude agent sessions that you created in other applications. By default, VS Code shows up to two recently updated external sessions. Select one from the Sessions list, and you can view the conversation and continue it in VS Code using your Copilot subscription.
A banner at the top of the chat lets you configure how many external sessions appear. You can also use the External submenu in the Sessions list filter to choose which external sessions are shown. The chat.agentSessions.showExternal setting controls this behavior and can be changed at any time.
Why it matters: Your agent sessions are no longer locked to the tool that started them. You can kick off a quick task from the Copilot app on your phone, then pick it up in VS Code when you’re back at your desk with full editor context. That’s a meaningful workflow shift.
Rubber Duck (Experimental)
Rubber Duck is an experimental feature that gives you a second opinion on an agent’s work — automatically. When you invoke the /rubber-duck command in a Copilot agent host session, a complementary model reviews what the primary agent has done and surfaces missed details or edge cases.
The name comes from the classic “rubber duck debugging” practice, but here the duck is another AI model. The idea is that different models have different strengths and blind spots. By having a second model review the work, you catch issues that the primary model might have missed.
Why it matters: As developers increasingly rely on AI agents for complex tasks, the risk of subtle errors grows. A second-opinion mechanism is a pragmatic safeguard — not a guarantee, but a useful checkpoint that costs you nothing to invoke. This aligns with GitHub’s broader push toward multi-model workflows in Copilot CLI.
Agents Window UX Improvements
The Agents window has been evolving rapidly over the last several releases, and 1.135 brings the most significant UX refinement yet.
Single-Pane Side Layout Is Now the Default
The single-pane layout — introduced as an option in 1.134 — is now the default for the Agents window on desktop. In this layout, session details and editors are located in a single side pane with a shared tab bar next to chat. The improvements in this release include:
- Adaptive diffs: Diffs use a side-by-side view when space permits and automatically switch to inline view when the side pane becomes too narrow. If you prefer inline at every width, use Always Show Inline Diff from the editor title menu.
- Decluttered action bar: Editor-specific actions for diffs, view modes, code review, and attachments have moved to the editor title area. The shared header now focuses on showing or hiding Details.
If you prefer the classic layout, disable sessions.layout.singlePaneDetailPanel and reload the window.
Simplified Session Controls and Information
The session header has been redesigned to be less crowded:
- Session title gets the prominent position, with an overflow menu next to it grouping actions for creating a chat and pinning the session.
- Session information moves directly above the chat input, where it’s easier to find while you work. Pills can show changes, pull requests, issues, browsers the agent is interacting with, and artifacts from the session.
- The Changes pill shows live file and diff counts and opens the complete set of session changes. It remains visible whenever the session has changes.
- Right-click any pill to open a context menu and choose which pill types are visible.
When a session contains multiple chats, chat tabs replace the single-chat header, making it easier to switch between related conversations.
Why it matters: The Agents window was getting busy. Between session headers, search boxes, action bars, and pills, there was a lot competing for attention. This redesign pushes the important stuff forward (session title, conversation, changes) and tucks the rest away. The adaptive diff behavior is a nice touch — no more manually switching between inline and side-by-side.
Detailed Chat Turn Usage
Ever wondered exactly how many tokens a particular chat turn consumed? VS Code 1.135 redesigns the chat response footer to show you.
When you hover over the footer of a chat response, you now see a per-model breakdown of:
- Input tokens
- Cached input tokens
- Output tokens
This gives you granular visibility into your chat usage, model by model, turn by turn. For developers using BYOK (bring your own key) models or managing Copilot credit budgets, this level of detail is essential.
Why it matters: Token usage has been opaque for too long. As developers mix models — switching between Copilot subscription models and BYOK models within the same session — understanding where your tokens go helps you make informed decisions about which models to use for which tasks.
Chat Improvements
Editor-Style Sticky Scroll for Chat (Experimental)
Sticky scroll for chat prompts — first introduced in 1.133 — has been refined to be more consistent with sticky scroll in the editor. The current prompt stays visible as you scroll through long responses, making it easier to track which response belongs to which question. Enable both chat.stickyScroll.enabled and chat.experimental.stickyScroll.enabled to try the redesigned experience.
Sandboxing Update
VS Code previously rolled out sandboxing for the local agent harness to 50% of users. After validation, the team determined that a full rollout would require more support and follow-up work at a time when focus is on higher-priority agent host and Copilot harness investments. The default rollout has been returned to 0%, but sandboxing remains available as an opt-in feature for users who want it.
Community Contributions
VS Code 1.135 includes contributions from 17 community contributors. Notable contributions:
- Simon Siefke continued their streak of memory leak fixes with three more: markersTable, mainThreadDocumentsAndEditors, and settings preview indicator
- Julia Gong added an optimized PatchBased02 prompt strategy for NES
- Ryan Ewen fixed a case where failed tool calls were presented as successful
- Zain Nadeem fixed PowerShell quoting for runInTerminal environment values and improved Workspace Trust handling
- Akshat Anand fixed Modern UI panel title tab centering in the 32px header
Issue tracking contributions from John Murray, Xavier Guarch, homeworld614, Johnny Noble, and wenma531 helped triage and verify community reports.
Should You Update?
Yes. VS Code 1.135 is a quality-of-life release that doesn’t introduce breaking changes. The external sessions feature alone is worth the update if you use Copilot or Claude across multiple tools. The redesigned Agents window layout makes the agent experience feel more polished, and the chat usage breakdown is a long-requested transparency feature.
VS Code is rolling out gradually to all users. Use Check for Updates in VS Code to get the latest version immediately, or download the nightly Insiders build to try new features as soon as they’re available.
What’s your favorite feature in VS Code 1.135? Let us know on X — we’re always interested in hearing how these updates land in real workflows.