Thinking summary dropdown no longer appears in VS Code transcript (v2.1.138)

Environment

• Extension: Claude Code for VS Code v2.1.138 (installed 2026-05-09)
• VS Code on macOS (Darwin 25.2.0, arm64)
• Model: Opus 4.7 (1M context)
• Fast mode: off

Settings

~/.claude/settings.json contains:

{
  "showThinkingSummaries": true,
  "effortLevel": "high"
}

No project-level override.

Expected

A collapsible thinking-summary row (chevron / triangle) appears in the transcript on turns where the model produces a summary. Clicking the row, or pressing Ctrl+O, expands it.

Actual

No triangle / chevron / thinking row appears in the transcript at all, on any turn — including multi-step turns where a summary would normally be emitted. Ctrl+O has nothing to expand.

Already tried

• Confirmed showThinkingSummaries: true in user settings
• Confirmed no project override in .claude/settings.local.json
• Reloaded the VS Code window (Developer: Reload Window)
• Confirmed Fast mode is off (so thinking should be emitted)

Notes

Schema in the extension bundle confirms showThinkingSummaries is the correct key. The UI element itself appears to no longer render.