Function ensure_vscode_compat_fields 

pub fn ensure_vscode_compat_fields(state: &mut Value, session_id: Option<&str>)

Ensure a JSONL kind:0 snapshot’s v object has all fields required by VS Code’s latest session format (1.109.0+ / version 3). Missing fields are injected with sensible defaults so sessions load reliably after recovery, conversion, or compaction.

Required fields that VS Code now expects:

• version (u32, default 3)
• sessionId (string, extracted from filename or generated)
• responderUsername (string, default “GitHub Copilot”)
• hasPendingEdits (bool, default false)
• pendingRequests (array, default [])
• inputState (object with mode, attachments, etc.)