feat: [TBB] render streaming thinking blocks in chat turns (Thinking Part 3) by ethanyhou · Pull Request #157 · microsoft/copilot-for-eclipse

ethanyhou · 2026-05-08T14:21:33Z

Should be reviewed after: #156

Renders the model's thinking deltas in a collapsible banner above each assistant turn (Copilot and subagent), backed by the LSP plumbing added in the previous PR.

Test:

Chat using Claude or GPT advance model and let the model think.
On thinking, the spinner should rotate with thinking body appending (The subtitle is selectable, GPT model prefers it):
- GPT:
- Claude:
The thinking block should auto collapse once thinking is finished but user can click to check the thinking content:
Cancel an ongoing thinking:
If you are lucky, sometimes the GPT model will think twice a time. This is a mock:

Adds the protocol surface for streaming model-thinking content from the language server: - Thinking record + ThinkingTypeAdapter (tolerates the server's mixed wire shape for ext: string delta or array of fragments). - ChatProgressValue.thinking field (with equals/hashCode/toString updates). - thinking/generateTitle JSON request (GenerateThinkingTitleParams/Response, server interface, connection wrapper). - Register ThinkingTypeAdapter.Factory in CopilotLauncherBuilder. No behavior change yet; UI plumbing follows in a stacked PR.

Renders the model's thinking deltas in a collapsible banner above each assistant turn (Copilot and subagent), backed by the LSP plumbing added in the previous PR. - ThinkingBlock: collapsible streaming banner (spinner -> generated title / cancelled), markdown body parsed into titled sections. - ThinkingSection: gutter dot + bold title + markdown body for each parsed section. - ThinkingTurnWidget: extends BaseTurnWidget, accumulates Thinking deltas, seals on first reply/agent round, fires thinking/generateTitle, and finalizes on cancel. - BaseTurnWidget: onChatMessageCancelled hook (default no-op) so subclasses can react to cancel events. - CopilotTurnWidget / SubagentTurnWidget / SubagentMessageBlock: re-parented onto ThinkingTurnWidget. - ChatContentViewer: routes thinking deltas to the active turn, seals before reply/agent rounds, seals at WorkDoneProgressKind.end. - ChatView: don't drop progress reports that carry only thinking content. - Messages / messages.properties: NLS keys for the in-progress / cancelled / expand / collapse strings. - dark.css / light.css: shared secondary-text color rule for the new ThinkingBlock selector.

jdneo · 2026-05-10T02:53:05Z

Why not directly merge into main? Then we can roll out it first in nightly

ethanyhou · 2026-05-10T09:42:58Z

@jdneo, because this PR is based on the branch ethan/thinking-lsp, if I merge it to main, the branch ethan/thinking-lsp's change in PR #156 will also be included in this PR and hard for you to review. That’s why I noted in the PR description that this PR should be reviewed after #156, since once #156 is merged, the target branch will automatically switch to main.

jdneo · 2026-05-11T01:58:42Z

ethanyho

I see. #156 is merged, pls update the pr to resolve conflict

Co-authored-by: Copilot <copilot@github.com>

ethanyhou · 2026-05-11T09:01:25Z

@jdneo Conflict is resolved.

Copilot

Pull request overview

Adds UI support in the chat view to render streaming “thinking” deltas from the language server as collapsible banners on assistant/subagent turns, leveraging the LSP protocol surface introduced in the prior PR.

Changes:

Introduces ThinkingBlock/ThinkingSection UI components and a ThinkingTurnWidget base class to manage streaming, sealing, and cancellation.
Wires thinking deltas into turn processing (ChatContentViewer, ChatView) and adds NLS + CSS styling for the new UI.
Updates Copilot/subagent turn widgets to use the new thinking-enabled base type.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/ThinkingTurnWidget.java	New base widget to accumulate thinking deltas, manage blocks, and seal/finalize with generated titles.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/ThinkingBlock.java	New collapsible “Thinking” banner UI with spinner, parsing into sections, and finalize/cancel visuals.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/ThinkingSection.java	New section widget (gutter + markdown body) used by `ThinkingBlock` during streaming.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/CopilotTurnWidget.java	Switches Copilot assistant turn to `ThinkingTurnWidget` base.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/SubagentTurnWidget.java	Switches subagent turn to `ThinkingTurnWidget` base.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/SubagentMessageBlock.java	Updates stored/returned subagent widget type to `ThinkingTurnWidget`.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/ChatContentViewer.java	Plumbs thinking deltas into turn rendering; seals thinking when reply/tool output begins and on turn end.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/ChatView.java	Avoids dropping “thinking-only” progress events by extending the empty-report guard.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/BaseTurnWidget.java	Adds cancel hook (`onChatMessageCancelled`) and clarifies reset behavior relative to thinking/subagent blocks.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/messages.properties	Adds localized strings for thinking banner titles/tooltips.
com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/Messages.java	Adds NLS fields for the new thinking banner strings.
com.microsoft.copilot.eclipse.ui/css/light.css	Extends secondary-text styling to thinking widgets in light theme.
com.microsoft.copilot.eclipse.ui/css/dark.css	Extends secondary-text styling to thinking widgets in dark theme.

jdneo · 2026-05-12T12:15:23Z

When I tried this pr, I found for every thinking block, it always renders a dot point at its last. Where is it comes from?

ethanyhou · 2026-05-12T12:58:52Z

When I tried this pr, I found for every thinking block, it always renders a dot point at its last. Where is it comes from?

In ThinkingSestion.java Line 71:

    Canvas dot = new Canvas(this, SWT.NONE);
    GridData dotData = new GridData(SWT.CENTER, SWT.CENTER, false, false);
    dotData.widthHint = GUTTER_WIDTH;
    dotData.heightHint = DOT_DIAMETER + 4;
    dot.setLayoutData(dotData);
    dot.addPaintListener(e -> {
      e.gc.setAntialias(SWT.ON);
      e.gc.setBackground(e.display.getSystemColor(SWT.COLOR_WIDGET_NORMAL_SHADOW));
      Rectangle area = ((Canvas) e.widget).getClientArea();
      int cx = (area.width - DOT_DIAMETER) / 2;
      int cy = (area.height - DOT_DIAMETER) / 2;
      e.gc.fillOval(cx, cy, DOT_DIAMETER, DOT_DIAMETER);
    });

    ChatMarkupViewer titleView = new ChatMarkupViewer(this, SWT.LEFT | SWT.WRAP); 
    StyledText titleWidget = titleView.getTextWidget();
    titleWidget.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false));
    titleWidget.setEditable(false);
    titleWidget.setMargins(0, 0, 0, 0);
    UiUtils.applyCssClass(titleWidget, SECONDARY_TEXT_CSS_CLASS, stylingEngine);
    titleView.setMarkup("**" + titleText + "**");
  }

jdneo · 2026-05-13T00:56:14Z

One more comment:

Currently the spinner will keep running after the content of the thinking block is finished, and disappear until the title is generated.

Can we just dispose the spinner after the content is complete?

ethanyhou requested review from duzitong, jdneo and xinyi-gong as code owners May 8, 2026 14:21

ethanyhou changed the title ~~feat: render streaming thinking blocks in chat turns~~ feat: [TBB] render streaming thinking blocks in chat turns (Thinking Part 3) May 8, 2026

ethanyhou force-pushed the ethan/thinking-ui branch from 63c65c1 to a55b8af Compare May 8, 2026 14:37

ethanyhou force-pushed the ethan/thinking-ui branch from a55b8af to f7e9bd0 Compare May 8, 2026 15:08

Base automatically changed from ethan/thinking-lsp to main May 11, 2026 01:57

Merge branch 'main' into ethan/thinking-ui

bca812e

Co-authored-by: Copilot <copilot@github.com>

Copilot AI review requested due to automatic review settings May 11, 2026 09:01

Copilot started reviewing on behalf of ethanyhou May 11, 2026 09:01 View session

Copilot AI reviewed May 11, 2026

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a20bb35

jdneo reviewed May 12, 2026

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Comment thread com.microsoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/ThinkingBlock.java

Comment thread ...crosoft.copilot.eclipse.ui/src/com/microsoft/copilot/eclipse/ui/chat/ThinkingTurnWidget.java

Address comments.

d1f1c74

jdneo mentioned this pull request May 12, 2026

Investigate whether to use MarkupViewer or Label to render a thinking block title #178

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jdneo commented May 12, 2026

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ethanyhou commented May 8, 2026 •

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ethanyhou commented May 10, 2026 •

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