Subagent activity UX. by gundermanc · Pull Request #17570 · google-gemini/gemini-cli

gundermanc · 2026-01-26T19:39:42Z

Summary

Improves the subagents UX to show the 3 most recent individual tool calls, live, as they happen.

Note that this is an incremental step and lacks some refinements. e.g.: pressing 'no' in the confirmation dialog fully cancels the subagent rather than pausing execution and letting you intervene.

It also doesn't yet support multiple subagents running in parallel.

Fixes #14309

Pre-Merge Checklist

gemini-code-assist · 2026-01-26T19:40:06Z

Summary of Changes

Hello @gundermanc, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly upgrades the user experience for interacting with subagents by implementing a structured, real-time progress display. Instead of basic text output, the CLI now renders a dynamic view of subagent operations, including their thoughts, tool executions, and any encountered errors. This change provides users with clearer insights into the subagent's current state and actions, making the interaction more transparent and informative.

Highlights

Enhanced Subagent Activity Display: Introduced a new React component, SubagentProgressDisplay, to provide a richer and more detailed real-time view of subagent activity within the CLI. This replaces simple text updates with structured progress objects.
Structured Subagent Progress Streaming: The LocalSubagentInvocation now streams SubagentProgress objects, which encapsulate the subagent's name and a list of recent activities (thoughts, tool calls, errors), allowing for dynamic UI updates.
Improved Tool Argument Display: Tool call arguments are now intelligently formatted for display, prioritizing a 'description' field, falling back to 'command', 'file_path', or other relevant arguments, and truncating long strings for readability.
Refined Error Handling for Subagents: Subagent execution errors are now captured and presented within the SubagentProgress object, ensuring that error states are visually integrated into the activity stream rather than being displayed as raw error messages.
New Types for Subagent Progress: Added SubagentActivityItem and SubagentProgress interfaces in @google/gemini-cli-core to formally define the structure of subagent activity and progress data.
Tool Registry Warning: Added a debug warning in LocalAgentExecutor when a tool referenced by an agent is not found in the parent registry, improving diagnosability.

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Code Review

The pull request introduces a new UI component for displaying subagent activity and integrates it into the existing tool result display. It also refactors the subagent invocation logic to stream progress updates as structured objects rather than plain strings, which is a significant improvement for user experience. Tests have been updated to reflect these changes. However, there are a couple of high-severity issues related to redundant truncation logic and a breaking change in the ToolResult API contract, which also touches upon maintaining UI consistency across components.

packages/cli/src/ui/components/messages/SubagentProgressDisplay.tsx

packages/core/src/agents/local-invocation.ts

github-actions · 2026-02-25T16:59:15Z

Size Change: +12.4 kB (+0.05%)

Total Size: 25.8 MB

Filename	Size	Change
`./bundle/gemini.js`	25.3 MB	+12.4 kB (+0.05%)

ℹ️ View Unchanged

Filename	Size
`./bundle/node_modules/@google/gemini-cli-devtools/dist/client/main.js`	221 kB
`./bundle/node_modules/@google/gemini-cli-devtools/dist/src/_client-assets.js`	227 kB
`./bundle/node_modules/@google/gemini-cli-devtools/dist/src/index.js`	11.5 kB
`./bundle/node_modules/@google/gemini-cli-devtools/dist/src/types.js`	132 B
`./bundle/sandbox-macos-permissive-open.sb`	890 B
`./bundle/sandbox-macos-permissive-proxied.sb`	1.31 kB
`./bundle/sandbox-macos-restrictive-open.sb`	3.36 kB
`./bundle/sandbox-macos-restrictive-proxied.sb`	3.56 kB
`./bundle/sandbox-macos-strict-open.sb`	4.82 kB
`./bundle/sandbox-macos-strict-proxied.sb`	5.02 kB

_{compressed-size-action}

gemini-cli · 2026-02-26T03:00:44Z

Hi there! Thank you for your contribution to Gemini CLI. We really appreciate the time and effort you've put into this pull request.

To keep our backlog manageable and ensure we're focusing on current priorities, we are closing pull requests that haven't seen maintainer activity for 30 days. Currently, the team is prioritizing work associated with 🔒 maintainer only or help wanted issues.

If you believe this change is still critical, please feel free to comment with updated details. Otherwise, we encourage contributors to focus on open issues labeled as help wanted. Thank you for your understanding!

gundermanc

deleted

abhipatel12

LGTM with one comment about the thought being sticky and a couple of other nits/thoughts for later

abhipatel12 · 2026-02-27T22:01:03Z

packages/core/src/agents/local-invocation.ts


      // Create an activity callback to bridge the executor's events to the
      // tool's streaming output.
      const onActivity = (activity: SubagentActivityEvent): void => {


nit: Maybe not now, but could be an opportunity to extract some of this into a separate method, etc to make it easier to read this file.

abhipatel12 · 2026-02-27T22:02:17Z

packages/core/src/agents/local-invocation.ts


 const INPUT_PREVIEW_MAX_LENGTH = 50;
 const DESCRIPTION_MAX_LENGTH = 200;
+const MAX_RECENT_ACTIVITY = 3;


I think for now this probably makes sense but ideally the CLI/TUI layer is completely in charge of what they want to display, etc. The core should really just emit what it's doing, etc.

But with the state of things, this is great since we already do this for the other fields.

abhipatel12 · 2026-02-27T22:10:19Z

packages/core/src/agents/local-invocation.ts


 const INPUT_PREVIEW_MAX_LENGTH = 50;
 const DESCRIPTION_MAX_LENGTH = 200;
+const MAX_RECENT_ACTIVITY = 3;


From testing this out, wdyt of keeping it as 3 but making sure the top 1 is always a "thought'.

Sometimes, there a long chain of no thought tool calls and it can be harder to gauge what the subagent is doing. With a thought i have an idea of the latest CoT reasoning.

I'm not seeing any thoughts bubbling through anymore for some reason. In the interest of unblocking this piece, I'm going to check in this PR and follow up with cleanup for thoughts.

gemini-cli bot added the priority/p1 Important and should be addressed in the near term. label Jan 26, 2026

gemini-code-assist bot reviewed Jan 26, 2026

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packages/cli/src/ui/components/messages/SubagentProgressDisplay.tsx Outdated Show resolved Hide resolved

packages/core/src/agents/local-invocation.ts Show resolved Hide resolved

gundermanc added 2 commits February 24, 2026 23:22

Subagent activity UX.

7762440

Fix ESC.

7e25901

gundermanc force-pushed the gundermanc/subagent-ux branch from ebd3bbb to 7e25901 Compare February 25, 2026 16:56

gemini-cli bot closed this Feb 26, 2026

gundermanc reopened this Feb 26, 2026

gundermanc added 2 commits February 26, 2026 16:06

Fixup types.

a3d47a8

Fix linter error.

4dd4019

gundermanc commented Feb 27, 2026

View reviewed changes

gundermanc added 7 commits February 26, 2026 16:27

UX tests.

5e4ddf9

Fix build.

037fef2

Fix icon and scrolling.

9b8c5fd

Ux change.

92d15d8

Bubble up aborts.

a43d43a

Use friendly names.

616acda

Fix tests.

837bd10

gundermanc marked this pull request as ready for review February 27, 2026 04:23

gundermanc requested a review from a team as a code owner February 27, 2026 04:23

gemini-cli bot added the status/need-issue Pull requests that need to have an associated issue. label Feb 27, 2026

Merge remote-tracking branch 'origin/main' into gundermanc/subagent-ux

c96ed89

gundermanc removed the status/need-issue Pull requests that need to have an associated issue. label Feb 27, 2026

gemini-cli bot added area/core Issues related to User Interface, OS Support, Core Functionality area/agent Issues related to Core Agent, Tools, Memory, Sub-Agents, Hooks, Agent Quality 🔒 maintainer only ⛔ Do not contribute. Internal roadmap item. labels Feb 27, 2026

abhipatel12 approved these changes Feb 27, 2026

View reviewed changes

Merge remote-tracking branch 'origin/main' into gundermanc/subagent-ux

cd9c1cb

gundermanc enabled auto-merge March 2, 2026 20:53

gundermanc added this pull request to the merge queue Mar 2, 2026

Merged via the queue into main with commit 7ca3a33 Mar 2, 2026
27 checks passed

gundermanc deleted the gundermanc/subagent-ux branch March 2, 2026 21:22

gemini-code-assist bot mentioned this pull request Mar 3, 2026

Changelog for v0.33.0-preview.0 #21030

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BryanBradfo pushed a commit to BryanBradfo/gemini-cli that referenced this pull request Mar 5, 2026

Subagent activity UX. (google-gemini#17570)

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struckoff pushed a commit to struckoff/gemini-cli that referenced this pull request Mar 6, 2026

Subagent activity UX. (google-gemini#17570)

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liamhelmer pushed a commit to badal-io/gemini-cli that referenced this pull request Mar 12, 2026

Subagent activity UX. (google-gemini#17570)

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