plat 527

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PLAT-527 — Chat scroll flickers after switching between workflows (cause not found)

Field	Value
State	open
Priority	P2
Product	app
Area	chat
Summary	open: cause not found, three suspects, needs a reproduction.

Coordination	Value
State	open: cause not confirmed; owner chose to keep it open (2026-10-05)
Priority	P2
Date	2026-10-05
Owner	frontend-chat

Source

Owner, local app: "the chat flickers a lot", then "scroll filter is there even now", then "it starts after we switch between workflows". Fine before any switch.

Checked (code and history read only; nothing run in the app)

• Workflow to Crew unmounts the old chat (App.tsx:933-985); switching between workflows keeps one ChatArea mounted and only the tabId changes (WorkflowLayout.tsx:2470).
• No leaking scroll observers, listeners or intervals found (useTranscriptScroll.ts, ChatArea.tsx, WorkflowLayout.tsx).
• The outer chat scroller steps aside while the transcript shows (ChatArea.tsx:3565), so two scrollers do not fight over one container.
• Server log: one chat re-subscribed to its event stream several times within seconds around the switches (18:55 to 18:58); no errors.

Suspects (none confirmed)

1. The follow-the-bottom logic fights Virtuoso after the list rebuilds with unmeasured rows (useTranscriptScroll.ts:174-191, 214-215, 324-337; TerminalEventTranscript.tsx:1044). A code comment already says it "can fight itself".
2. Older history pages cached per chat (commit 89e1040fa, 2026-10-05) are joined to live events without de-duplicating by event id (ChatArea.tsx:876-880); an overlap would give duplicate row keys and re-measuring. Only if earlier pages were loaded. Overlap not shown.
3. The manual flag stays set after a wheel gesture, so a layout-driven scroll counts as the reader scrolling up and later height changes shift the view (useTranscriptScroll.ts:270-312, 331-334).

Left

• Reproduce and say which suspect: a short screen recording, whether it needs scrolling up or "Load earlier" first, or a temporary log of move / scrollToIndex calls after a switch.
• Then fix the confirmed one only; do not ship a guess into the recently reworked scroll code.

Register notes

PLAT-527, open: cause not found, three suspects, needs a reproduction.