Fix: Restore Stop Generation Button During Agent Session Execution Loop

[angelplusultra]

Pull Request Type

• ✨ feat (New feature)
• 🐛 fix (Bug fix)
• ♻️ refactor (Code refactoring without changing behavior)
• 💄 style (UI style changes)
• 🔨 chore (Build, CI, maintenance)
• 📝 docs (Documentation updates)

Relevant Issues

resolves #5969

Description

<StopGenerationButton /> never appeared during the first execution loop of a new agent session. Two causes:

1. The HTTP handoff that starts an agent session ends with a statusResponse ("Swapping over to agent chat"), and handleChat treats every statusResponse as end-of-exchange, clearing loadingResponse right as the agent starts working.
2. The websocket message listener called setLoadingResponse(true) then setLoadingResponse(false) in the same synchronous handler, which React 18 batches into a net false on every incoming agent event — so the loading state could never recover.

Fix (frontend only):

• loadingResponse is set on when the agent websocket is established, and the closing handoff statusResponse is no longer allowed to clear it once the session is active (guards against either ordering of the handoff chunks).
• Each socket event now maps to a loading state via agentEventLoadingState() in utils/chat/agent.js: work events (status updates, text chunks, tool calls) keep it on; awaiting-user events (WAITING_ON_INPUT — previously ignored by the frontend entirely — plus toolApprovalRequest/clarificationRequest) turn it off; passive bookkeeping events (rename_thread, chatId, usageMetrics, citations, etc.) leave it untouched. The passive bucket matters because rename_thread arrives after the async chat save + thread auto-rename complete, i.e. after WAITING_ON_INPUT, and would otherwise re-show the stop button indefinitely.

The stop button now stays visible for the entire execution loop and hands back to the send button when the agent is waiting on the user.

Visuals (if applicable)

Additional Information

Developer Validations

• I ran yarn lint from the root of the repo & committed changes
• Relevant documentation has been updated (if applicable)
• I have tested my code functionality
• Docker build succeeds locally

[shatfield4]

Just 1 small nit here, other than that LGTM. It works and solves the bug in a simple way.

[timothycarambat]

@angelplusultra can we get this moving?

[timothycarambat]

Noting this because i was testing this prior to review:

With LMStudio, if I kill the response when generating a response - the UI properly shows "Agent session ended" and the button returns to a sendable state. However on the backend the message continues.

The intention for this PR is JUST to fix the button state, yeah? Because on reload of the page the completed message is present.

If this PR is JUST for button state, we need to stack PRs as merging just this to mater results in still a misleading state and we should merge this fix + actual stopping generation in a single commit.

[angelplusultra]

Noting this because i was testing this prior to review:

With LMStudio, if I kill the response when generating a response - the UI properly shows "Agent session ended" and the button returns to a sendable state. However on the backend the message continues.

The intention for this PR is JUST to fix the button state, yeah? Because on reload of the page the completed message is present.

If this PR is JUST for button state, we need to stack PRs as merging just this to mater results in still a misleading state and we should merge this fix + actual stopping generation in a single commit.

Yes, the intention of this PR is just to restore the functionality of the abort feature as is. The state of the button was lost somehow in a v2 migration. We are splitting the true abort feature into 2 steps. First fix it as is. Then refactor to be a full end-to-end abort.