#32823 base red: message-preview opens the "Received N messages" row before it reads a preview

Base-red-job: web / react-apps-check

webviews/test/message-preview-browser.test.ts fails on every recent base web run (41556018937, 41556254089, 41556613101, 41557134592, 41555236821 at 3891b41b): line 70 expect(.cv-received count).toBe(2) gets 0, and line 138 (Minimal Mode) times out reading .cv-received__preview.

Cause: #32720 ("a turn's inbox notices and received lines are one 'Received N messages' row") deliberately gathers received messages next to each other into one "Received N messages" row whose messages show only once it opens. The agent-pane.message-preview stage has two received messages in a row, so they now sit inside that closed row. Green at 708aa6df, red from the run that includes #32720.

Fix: the test's open() opens the "Received N messages" row when the stage draws one, then reads each message's own line, toggle and preview inside it, the same way c6e52c4eaae8 handled the earlier fold. No product change; the behaviour is #32720's intended design.

Observed / Not run

• Read: the gallery fixture, #32720's projection (laneNoticeBatches.ts receivedRun) and its received-messages-columns-browser.test.ts selectors.
• The test runs in this PR's web CI; not run locally (lane VM).

Changelog

none

Agent session: agent session

🤖 Generated with Claude Code

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Summary by cubic

Fixes the failing message-preview-browser.test.ts by opening the "Received N messages" row before reading message previews. #32720 groups consecutive received messages into one collapsible row that renders its messages only once opened, so the test now expands that row when the stage draws one and then reads each message's line, toggle, and preview inside it. No product change; the grouped row is #32720's intended behavior.