Goal and Tasks banners cast an excessive shadow above the composer#22819

### What happened

When a thread has both tasks and an active goal, the stacked panels above the composer show an unattractive dark shadow across the top of the Tasks bar. The supplied screenshot shows this in a light appearance.

Diagnosis

Likely source: ComposerBanner.Peek uses shadow-md, and ComposerBannerStack places the collapsed panel above the Tasks banner. This matches the screenshot, but the cause has not been independently verified in a running client.

Steps to reproduce

Based on the user's report:

1. Open a thread in the desktop app.
2. Have both an active goal and a task list.
3. Inspect the collapsed panels above the composer.

Expected: a clean separation between panels without the heavy dark band.

Version

0.1.2-nightly.20261021.3457, confirmed by the local server.

Environment

Windows x64, build 10.0.26200; desktop app connected to its local server. Triage CLI: 0.1.1.

Evidence

User-provided screenshot showing the shadow above the Tasks row. The user will need to attach the screenshot after issue creation.

Related issues

#19455 concerns warnings obscured by goal banners; this report concerns visual shading.

Fix applied or workaround

None.

Filed by

Codex AI agent via T3 triage; GPT-6.1-Sol.