[FEATURE] VSCode sidebar: bookmark/pin past conversations + public resumeSession command

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 "Past conversations" list in the official VSCode extension sidebar grows to hundreds of sessions over time, with no way to mark important ones for quick access. I currently have ~200 sessions across many project folders and have to scroll or search every time I want to revisit an in-progress investigation, a debugging session, or a chat that produced a useful artifact.

A secondary problem: third-party companion extensions cannot fill this gap themselves, because there is no public command to open a specific past session in the official sidebar webview. The webview channel that does this (launch_claude / teleport_session) is private to the official extension.

Proposed Solution

Primary request — bookmark/pin support in the official sidebar:

• A ★ (star/pin) icon next to each session in the "Past conversations" list, toggling bookmark state on click.
• A separate "Bookmarked" section pinned at the top of the sidebar (above the regular list) that shows only starred sessions.
• Bookmark state persisted locally (e.g. in globalState, or per-workspace if that fits the model better).
• Optional: keyboard shortcut to bookmark the currently open session.

Alternative Solutions

_No response_

Priority

High - Significant impact on productivity

Feature Category

CLI commands and flags

Use Case Example

Scenario: I'm investigating a tricky pricing bug across multiple sessions over several days. Each session is a long, expensive conversation with significant context. I want to bookmark three of them so I can flip between them quickly without losing my place.

Today:

1. Open the Claude sidebar.
2. Click "Past conversations".
3. Scroll through ~200 sessions to find the right one. Titles are auto-generated and similar across investigations, so I often have to open 2-3 wrong ones before finding it.
4. Lose 30 seconds per context switch. Repeat several times a day.

With bookmarks:

1. Open the Claude sidebar.
2. The three bookmarked sessions are pinned at the top.
3. Click the right one — instant.

Additional Context

Environment:

• VSCode extension version: 2.1.126
• OS: Windows 11
• ~200 past sessions across multiple project folders

Technical note for implementers:
The extension already has the plumbing — the webview message types list_sessions_request, get_session_request, rename_session, delete_session, teleport_session, and launch_claude (with resume) all exist in the bundle. A bookmark feature would mostly need a new persisted flag per session and UI affordance in the "Past conversations" panel. A public resumeSession VSCode command could be a thin wrapper around teleport_session/launch_claude.