[bobleer]

Summary

Reverts #3922 (db95809b9fc47716a91f8b618c592f5e7473d0a3) to restore the pre-#3922 FlowChat streaming cadence, event transport, and session/workspace switching baseline (15ac7c21b).

Type and Areas

Type: Regression fix (revert)

Areas: Desktop/Tauri, web UI, app-server-protocol, server/CLI event transport

Motivation / Impact

Manual desktop validation after merging #3922 showed bursty, start-stop FlowChat streaming behavior caused by stacked event coalescing/batching and long-stream typewriter step throttling. Reverting #3922 cleanly restores the proven baseline behavior while streaming pacing is redesigned separately.

Verification

• Confirmed git diff 15ac7c21b..HEAD is empty (exact byte-for-byte match with the commit immediately prior to perf(desktop): coalesce streaming events and isolate session/workspace switches #3922).
• pnpm run check:repo-hygiene — passed
• pnpm run check:core-boundaries — passed
• node scripts/check-git-object-sizes.mjs --base origin/main --head HEAD — passed
• pnpm --dir src/web-ui run gen:types && pnpm --dir src/web-ui exec tsc --noEmit — passed
• pnpm --dir src/web-ui exec vitest run src/flow_chat/hooks/useTypewriter.test.ts src/flow_chat/services/EventBatcher.test.ts src/flow_chat/components/FlowTextBlock.test.tsx src/flow_chat/components/modern/VirtualMessageList.session-switch.test.tsx — 4 files, 41 tests passed
• cargo check -p openbitfun-desktop — passed

Reviewer Notes

• AI-assisted PR; verification level: locally verified with type-checks, Rust check, boundary/hygiene audits, and focused FlowChat unit tests (remote surfaces restored to pre-perf(desktop): coalesce streaming events and isolate session/workspace switches #3922 baseline without live remote host testing in this revert).

Checklist

• This PR is focused and does not include secrets, temporary prompts, generated scratch files, or unrelated artifacts.
• Relevant verification is recorded above, or skipped checks are explained.
• User-facing strings, docs, and locales are updated where applicable.