VS Code extension: session tabs restore empty despite correct CLAUDE_CONFIG_DIR and intact .jsonl files (related to #45424)

Description

Session tabs in the VS Code extension restore with the correct title but empty
content after fully quitting (Cmd+Q) and reopening VS Code - even though
CLAUDE_CONFIG_DIR is correctly configured and the underlying .jsonl session
files are intact and up to date. This is a variant of #45424, but that issue
was closed as "not planned" while attributing the symptom to tab-close cache
eviction; this report shows the same symptom occurs even with a verified-correct
config and without explicitly closing tabs (full app quit/relaunch).

Environment

• macOS, VS Code extension (not CLI-only)
• CLAUDE_CONFIG_DIR set via claudeCode.environmentVariables in the profile's

settings.json (not a shell env var / alias), so it applies regardless of how
VS Code is launched (Dock, Spotlight, terminal)

Steps to reproduce

1. Work in a project over multiple days/weeks with several session tabs open
2. Fully quit VS Code (Cmd+Q)
3. Reopen VS Code - previously open tabs restore with correct titles
4. Click into a tab - panel is empty ("Untitled", no message history)

Diagnostics performed

• Confirmed claudeCode.environmentVariables in the profile's settings.json

correctly points CLAUDE_CONFIG_DIR to the intended directory

• Confirmed .jsonl session files in that directory are being written

correctly and are current (matching real-time activity, verified by file
mtimes)

• The extension's "Session history" dialog (Local tab) only surfaced sessions

from ~1 month prior, missing weeks of subsequent activity that exists on disk

• Inspected the workspace's state.vscdb (workspaceStorage):
• agentSessions.model.cache is populated (50/50 entries) exclusively by a

different chat provider (openai-codex) - no Claude Code entries, and
unrelated to Claude's own session list per the keys below

• Claude-specific keys (memento/webviewView.claudeVSCodeSessionsList,

workbench.view.extension.claude-sessions-sidebar.state, etc.) only
contain webview UI state (collapsed/size), not an actual session index

• Could not locate a readable on-disk index that would explain the stale

tab/session-list state - the actual session index appears to live in
extension-host memory and does not get correctly rebuilt/rehydrated on
reopen

Expected behavior

Session tabs and the "Session history" list should reflect the actual
.jsonl files on disk, especially given CLAUDE_CONFIG_DIR is explicitly and
correctly configured. Env misconfiguration can be ruled out as the cause here.

Workaround

claude --resume in the terminal correctly finds and resumes all sessions
that are invisible in the VS Code UI, confirming the data itself is intact.