Extended thinking no longer renders as a collapsible/clickable block

Thinking content still appears in output, but as plain non-collapsible text instead of the previous clickable/expandable block.

• Extension: anthropic.claude-code v2.1.226 (VSCode native extension, sidebar mode)
• Model: Sonnet 5 (confirmed via /model, supports extended thinking)
• Steps taken: updated VSCode, restarted, tried a fresh window — no change
• Checked and ruled out: no thinking-related overrides in global/project .claude/settings.json, no relevant environment variables, no suppressing VSCode user settings

Expected: thinking renders as a collapsible block as it previously did
Actual: thinking renders as plain text with no click/expand affordance