VS Code extension: older sessions not visible in sidebar after update

Description

Sessions created with older versions of Claude Code (e.g., 2.1.79) are not displayed in the VS Code extension sidebar after updating to a newer version (e.g., 2.1.83). The sidebar shows "No sessions yet" even though session data exists on disk.

New sessions created with the current version appear correctly.

Steps to reproduce

1. Have an existing session created with Claude Code version ≤ 2.1.81
2. Update Claude Code extension to 2.1.83+
3. Open the workspace folder in VS Code
4. Open Claude Code sidebar → Sessions list
5. Observe: "No sessions yet" — old sessions are missing, only newly created sessions appear

Investigation findings

• The .jsonl session files exist and are intact in ~/.claude/projects/<project-dir>/
• Session metadata (type, sessionId, cwd, ai-title, last-prompt) is present and correctly formatted
• A newly created session in the same workspace appears immediately in the sidebar
• Both old and new sessions share the same structure (queue-operation, user, assistant, ai-title, last-prompt)
• Both have userType: "external" — no difference in origin
• The old session can still be resumed via CLI (claude --resume)

Expected behavior

All sessions for a workspace should be visible in the sidebar, regardless of which Claude Code version created them.

Actual behavior

Only sessions created with the current extension version are shown. Older sessions are silently filtered out.

Environment

• VS Code: latest version
• Claude Code extension: 2.1.83
• Old session created with: 2.1.79
• OS: macOS (Darwin 25.3.0)

🤖 Generated with Claude Code