[FEATURE] VSCode extension: Quote affordance on assistant messages (parity with Claude.ai web and Claude Code on Windows)

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

The Claude Code VSCode native extension has no way to reference, quote, or re-inject a prior assistant message into the next prompt. Two other Claude surfaces already ship a quote affordance:

• Claude.ai web: select text inside a prior assistant message and a "Reply" affordance appears next to the selection. Clicking it inserts the selection as a > quoted block into the prompt input.
• Claude Code on Windows: right-click on any prior assistant message exposes a context menu with four items: Copy message, Copy as Markdown, Attach selection as context, Pin as chapter. When text is selected, "Attach selection as context" inserts the selected span as > quoted context for the next prompt; with no selection it falls back to the full message body.

In the VSCode extension, neither mechanism exists. Right-clicking on a rendered assistant message yields only the standard webview menu (Cut/Copy/Paste/Inspect). Selecting text and pressing Ctrl+C copies plain rendered prose, losing markdown structure (code fences, headings, lists, tables). The markdown loss is a known issue tracked separately as #54670.

Why this matters

Long-running sessions accumulate useful intermediate output: table of contents, code reviews, generated config, partial drafts. To build on a specific chunk of a prior assistant message, users currently:

1. Manually highlight and copy plain text (markdown structure lost, see #54670)
2. Paste into the prompt box
3. Manually wrap it in > quoting to disambiguate from new instructions

The other two surfaces eliminate this friction with one gesture. The VSCode extension is the daily driver for many developers, and this gap pushes them to switch surfaces mid-task to compose follow-ups.

Proposed Behavior

Add either mechanism (or both) to the VSCode extension's chat panel:

Option A. Right-click context menu on assistant messages (matches Claude Code on Windows)

1. Copy message: full message body, plain text
2. Copy as Markdown: full message body preserving markdown source (subsumes #54670)
3. Attach selection as context: wraps the highlighted span in a > quoted block in the prompt input. If no text is selected, falls back to the full message body.
4. Pin as chapter: bookmarks the message in the session outline / side panel

Option B. Reply affordance after text selection (matches Claude.ai web)

After the user selects text from a prior assistant message, a "Reply" / "Quote" button appears near the selection. Clicking inserts the selection as a > quoted block in the prompt input.

Acceptance Criteria

• [ ] In the VSCode extension chat panel, either right-click on an assistant message exposes the four-item context menu (Option A), or text selection surfaces a Reply/Quote affordance (Option B), or both
• [ ] "Copy as Markdown" preserves code fences, lists, headings, links, tables when pasted into a markdown-aware editor
• [ ] "Attach selection as context" / "Reply" inserts a > quoted block into the prompt input that the model receives as quoted prior content, not as a new user instruction
• [ ] Behavior reaches functional parity with Claude.ai web and Claude Code on Windows for the same gesture
• [ ] No duplicate insertion regression on quote injection. In Claude Code on Windows, "Attach selection as context" currently inserts the quoted block twice in the prompt editor (reproduced 2026-05-03; tracked as Bug 2 in #53241). The VSCode implementation must not replicate this bug.

Related

• #54670: VSCode extension Cmd+C / Ctrl+C on a selection in the chat panel loses all markdown formatting. Subset of this request; "Copy as Markdown" in Option A subsumes it.
• #53241: Claude Code on Windows, Bug 2: right-click "Attach message as context" double-pastes the message body in the next send. Primary repro 2026-05-03 on the same surface. The VSCode implementation must avoid replicating this behavior.
• #50386: Claude Code Desktop on macOS, Cmd+C with a selection in an assistant message copies the entire message block, not the selected span. Adjacent bug on a different surface, same UX gap around selection scope.
• #48099: Claude Code CLI feature request to "Open in side chat" from REPL text selection. Adjacent precedent for actions triggered by selecting prior assistant output, different goal (forked side conversation rather than inline quote).
• #26716: Native quote/citation UI for in-conversation message references. Closed as stale Feb 2026. Earlier broader feature request that did not get implemented; cited as prior art.

Environment

• Claude Code for VS Code extension, version 2.1.126 (current as of 2026-05-03, publisher anthropic.com on the VS Code Marketplace)
• Verified absent from extension docs at https://code.claude.com/docs/en/vscode (the docs cover @-mentions for files and editor selection, but no message-level copy/quote/attach affordance for chat messages)