The REST prefetch and the gateway `session.resume` already ran concurrently,
but the prefetch result was held until the runtime resume settled. A cold
profile build (skills / MCP / memory) can keep `session.resume` pending past
the hydration budget while the complete transcript is already in hand, so a
Bot Chat sat on the loader and burned its retries with readable history
off screen.
- Publish the grafted REST snapshot as soon as the prefetch resolves and
`isCurrentResume()` holds; the runtime path grafts only its live projection
onto that same snapshot, and the post-resume `chatMessageArraysEquivalent`
skip keeps reference identity when nothing changed (no second DOM build).
- Stamp the eagerly painted page with persisted-display provenance on the
runtime state so the warm-path gate admits it on the next switch.
- REST fallback after a resume rejection skips the redundant re-publish when
the early paint already shows the transcript.
Live repro (Electron e2e, session.resume stalled 25s via a temporary
backend shim): main never painted within 20s; with this fix the transcript
painted 150ms after the row click.
Supersedes #90130.
Co-authored-by: Alexandre Roumieu <269586168+alexandreroumieu-codeapprentice@users.noreply.github.com>
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