fix(cockpit): stop c-input demo double-submitting the user message

[blove]

What

The cockpit/chat/input demo (app-input) submitted every user turn twice, producing a phantom third chat-message in the list.

Root cause

<chat-input [agent]="agent"> already submits to its bound agent inside the primitive's onSubmit() and emits (submitted) purely as a post-submit notification. The demo also handled (submitted) by calling agent.submit() again:

<chat-input [agent]="agent" (submitted)="submitMessage($event)" />
// ...
submitMessage(content: string) { this.agent.submit({ message: content }); }

So each "Hello" produced two user messages with distinct ids → 3 chat-message elements where the e2e expects 2.

Fix

Drop the redundant (submitted) handler and the submitMessage method. The [agent] binding is the single submit path. Added a short comment so the pattern isn't reintroduced.

Verification

• nx e2e cockpit-chat-input-angular → 2 passed (the chat-message-list renders both turns / toHaveCount(2) assertion now green).
• nx lint/build for cockpit-chat-input-angular → green.

This is a pre-existing demo bug, surfaced (not caused) by the subagent-card work in #721 — fixed separately as requested.

🤖 Generated with Claude Code

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Project	Deployment	Actions	Updated (UTC)
threadplane	Ready	Preview, Comment	Jun 23, 2026 1:34am

[github-actions]

Claude finished @blove's task in 1m 0s —— View job

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Review

• Read diff and changed file
• Checked (submitted) contract in chat-input.component.ts
• Scanned other demo components for the same pattern
• Posted findings

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The fix is correct. ChatInputComponent.onSubmit() calls submitMessage(agent, text) internally and only then emits (submitted) as a post-submit notification (chat-input.component.ts:147–149). The removed submitMessage() handler was calling agent.submit() a second time, doubling every user turn.

The explanatory comment added in the template is good — the misuse pattern was easy to fall into and the comment prevents re-introduction.

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Issue: same double-submit bug exists in the messages demo

cockpit/chat/messages/angular/src/app/messages.component.ts has an identical copy of the bug that wasn't touched by this PR:

// line 72
<chat-input [agent]="agent" (submitted)="submitMessage($event)" />

// lines 94-96
submitMessage(content: string) {
  this.agent.submit({ message: content });
}

This will produce the same duplicate-message behaviour in the cockpit/chat/messages demo. Fix this →

(The chat.component.ts usage of (submitted)="onUserSubmitted()" is fine — that handler only does UI bookkeeping like pinned.set(true), it never calls agent.submit() again.)

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[github-actions]

Claude finished @blove's task in 43s —— View job

---

Review

• Read diff and source file
• Analyze correctness and patterns

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Verdict: LGTM. The fix is correct and minimal.

The root cause diagnosis is accurate — (submitted) is a post-submit notification, not a submit trigger, and the old demo was calling agent.submit() twice. Removing the submitMessage() method and the event binding is exactly the right fix.

One minor suggestion: the added HTML comment spans two lines where the code style guidelines prefer single-line comments. It could be collapsed to:

<chat-input [agent]="agent" />

But the two-liner version is still clear and explains a genuinely non-obvious API contract, so this is not blocking.

No other issues found — no correctness bugs, no security issues, no type-safety regressions, no Angular/RxJS pitfalls.

[github-actions]

Automated approval: this PR received an intelligent (AI) code review. See the review comments on this PR.