[BUG] Extended thinking dropdown no longer expandable in VSCode extension (Opus 4.7)

[samAd0san]

Preflight Checklist

• I have searched existing issues and this hasn't been reported yet
• This is a single bug report (please file separate reports for different bugs)
• I am using the latest version of Claude Code

What's Wrong?

In the Claude Code VSCode extension, I used to be able to expand a dropdown/collapsible block to view Claude's extended thinking while it was working on a task. That dropdown is no longer appearing in the chat UI.

Claude still appears to reason about tasks (responses reflect it), but there is no longer any visible thinking block in the conversation that I can click to expand. This happens across normal task prompts — including when the prompt contains trigger words like "think hard" or "ultrathink".

What Should Happen?

When Claude is working on a task — especially with extended-thinking trigger words like "think", "think hard", or "ultrathink" — a collapsible "Thinking" block should appear in the chat UI above Claude's response. Clicking it should expand to reveal Claude's internal reasoning/thinking summary, as it did in earlier versions of the VSCode extension.

Error Messages/Logs

No error messages are shown. The thinking block is silently absent from the UI — nothing is logged, nothing fails; the dropdown simply never renders.

Steps to Reproduce

1. Open the Claude Code VSCode extension.
2. Confirm the model is set to Opus 4.7 (claude-opus-4-7[1m]) via /model.
3. Start a new conversation.
4. Send a prompt that should trigger extended reasoning, e.g.:
   "think hard about how to refactor this function and explain your approach"
5. Wait for Claude's response to render.

Expected: a collapsible "Thinking" block appears above the final answer and can be expanded.
Actual: no thinking block appears anywhere in the chat. Only the final answer is shown.

Reproduces on every turn, across new and existing conversations.

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

Unknown — worked in a recent prior version of the VSCode extension but I did not note which one.

Claude Code Version

2.1.104 (Claude Code)

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

Context:

• Running Claude Code as the VSCode native extension (not the terminal CLI).
• Model: Opus 4.7 (claude-opus-4-7[1m]).
• OS: macOS (Darwin 25.0.0).
• The issue is not tied to any particular project or repo — it reproduces in every workspace.
• I have tried:
  • Using explicit thinking trigger words ("think", "think hard", "ultrathink") in prompts — no thinking block appears.
  • Starting fresh conversations — same behavior.
• No visible error, no console warning — the thinking UI element is simply absent.

If this is a known rendering regression specific to Opus 4.7 in recent extension versions, please confirm — otherwise happy to share a screen recording or VSCode extension logs if you can point me to where they live.

[github-actions]

Found 3 possible duplicate issues:

1. [BUG] Opus 4.7 thinking renders empty/unexpandable stub in VS Code extension #49757
2. [BUG] Opus 4.7 thinking summaries not rendered in VS Code extension #49322
3. Thinking summaries missing on Opus 4.7 — harness doesn't set display: "summarized" #49268

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🤖 Generated with Claude Code

[hifihedgehog]

Same bug on Windows / VS Code extension 2.1.x with Opus 4.7. Not macOS-specific.

Root cause is now public (credit to the workaround in #8477 (comment)): Opus 4.7 changed the API default for thinking blocks from display: "summarized" to display: "omitted". The blocks are still in the response stream, but the thinking field is empty unless the caller passes display: "summarized" explicitly. Documented in Anthropic's own migration guide: https://platform.claude.com/docs/en/about-claude/models/migration-guide#migrating-to-claude-opus-4-7

Net effect: showThinkingSummaries, alwaysThinkingEnabled, and viewMode: "verbose" have nothing to render, because Claude Code does not pass display: "summarized" when calling the Opus 4.7 API. showThinkingSummaries is the documented, official way to surface thinking in the VS Code extension, and it is silently broken on Opus 4.7. The settings surface never caught up to the API change.

Two undocumented workarounds (from the same comment):

1. Add to ~/.claude/settings.json:

   {
     "env": {
       "CLAUDE_CODE_EXTRA_BODY": "{\"thinking\":{\"type\":\"adaptive\",\"display\":\"summarized\"}}"
     }
   }

2. Hidden CLI flag: --thinking-display summarized

The env var approach works for the VS Code extension since it delegates to the CLI.

Why this is high-priority, not a cosmetic regression:

Visible real-time thinking was load-bearing for the steering loop. With it visible, you could stop the model going down a wrong branch before it spent N turns of token budget on a wrong premise; you could verify it had internalized constraints from CLAUDE.md / memory rather than hallucinated them; and you could audit assumptions before committing to a plan.

With it hidden behind an unexpandable pill, you cannot tell whether a wrong final answer came from a wrong premise or a wrong execution of a right premise. Silent assumption drift becomes invisible until after the wrong action is taken. "Thought for 376s" is a duration, not a signal. It tells you nothing actionable. This is a regression in the developer's ability to supervise the agent.

On the user side: this is a paid product. Pro at $20/month, Max at $100–$200/month. Paying customers should not have to monkey-patch cli.js, reverse-engineer an undocumented CLAUDE_CODE_EXTRA_BODY env var, or scrape issue threads to recover functionality that worked in the previous release of the same product. The workaround being undocumented is itself a bug. The gap between what the API supports and what Claude Code exposes as a first-class setting keeps widening with every model bump.

Related open issues, same root problem:

• #8477 — original tracking issue where the API-default change was traced and the workaround was published
• #49268 — harness doesn't set display: "summarized" for Opus 4.7 (same root cause, named explicitly)
• #49757 — empty/unexpandable stub in VS Code extension (Opus 4.7)
• #49902 — thinking summaries not rendered (VS Code extension 2.1.112)
• #49322 — thinking summaries not rendered in VS Code extension (Opus 4.7)
• #48065 — thinking summaries not displayed when showThinkingSummaries enabled
• #49739 — toggle button inverted, no visual feedback (v2.1.112), likely a related UI-state bug
• #30958 — earlier transcript/TUI variant of the same regression (v2.1.69)
• #33163 — "Bring back thinking" feature request, same underlying ask

What would actually resolve this:

1. Pass display: "summarized" by default for Opus 4.7+ when showThinkingSummaries and alwaysThinkingEnabled are on. Or expose a first-class thinkingDisplay setting alongside the existing thinkingEnabled and effortLevel.
2. Restore the expandable thinking block in the VS Code extension chat panel so showThinkingSummaries actually shows summaries when the data is present.
3. Update the docs so they reflect current showThinkingSummaries semantics on Opus 4.7+ instead of describing behavior that no longer applies.