Expand truncated prompts in channel feeds

[k11kirky]

Problem

Long task prompts in channel feeds are truncated with no way to read the full message.

Changes

• Add a More/Less control when a channel task prompt is visually truncated
• Keep the behavior consistent while the task is starting and after it is created

Why: Users need to read the complete prompt without leaving the channel context.

How did you test this?

• pnpm --filter @posthog/ui exec vitest run src/features/canvas/components/ChannelFeedView.test.tsx
• pnpm --filter @posthog/ui typecheck
• pnpm exec biome check packages/ui/src/features/canvas/components/ChannelFeedView.tsx packages/ui/src/features/canvas/components/ChannelFeedView.test.tsx

Automatic notifications

• Publish to changelog?
• Alert Sales and Marketing teams?

---

Created with PostHog Code

[trunk-io]

😎 Merged successfully - details.

[github-actions]

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit cea3fce.}

[posthog]

✅ Visual changes approved by @k11kirky — baseline updated in 4595c1e.

View this run in PostHog

2 changed.

[greptile-apps]

Prompt To Fix All With AI

Fix the following 1 code review issue. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 1
packages/ui/src/features/canvas/components/ChannelFeedView.tsx:451-455
**Expansion State Is Not Announced**

The new control changes whether the prompt is collapsed, but it does not expose that state to assistive technology. Screen-reader users hear “more” or “less” without the button’s expanded state, so the new interaction does not communicate whether the full prompt is currently visible.

```suggestion
        <button
          type="button"
          aria-expanded={expanded}
          className="text-muted-foreground text-xs underline underline-offset-2 hover:text-foreground"
          onClick={() => setExpanded((value) => !value)}
        >
```

_{Reviews (1): Last reviewed commit: "chore(visual): update storybook baseline..." | Re-trigger Greptile}

[github-actions]

Contained UI-only feature (expand/collapse for truncated feed prompts) with new tests; the sole reviewer concern (missing aria-expanded) is already implemented in the diff, and no risky territory (auth, data, API, CI, deps) is touched.

• Author wrote 0% of the modified lines and has 68 merged PRs in these paths (familiarity MODERATE).
• 👍 on the PR from greptile-apps[bot].

Gate mechanics and policy version

Gate		Result
prerequisites	✓	all clear
deny-list	✓	no deny categories matched
size	✓	64L, 2F substantive, 109L/3F incl. docs/generated/snapshots — within ceiling
tier	✓	T1-agent / T1c-medium (109L, 3F, two-areas, unknown)
stamphog 2.0.0b3		.stamphog/policy.yml @ 7b426cd · reviewed head cea3fce

[tatoalo]

noice

[k11kirky]

/trunk merge