Agent Note: The banner sweeps in; the subtitle line is gone

Status: implemented Archived: 2026-07-26

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Superseded by the no-banner Agent Note: the banner itself was removed, taking the sweep with it.

Problem

The startup-slogans Agent Note replaced the instructional welcome line with a random slogan bank revealed by a per-character typewriter. In use the quotes read as weird — random flavor text in a tool's header — and the animation was slow (40 ms/char over a full sentence) while animating only one line of a four-line banner. This note supersedes that decision's slogan half; the removal of the configured demo welcome and the animation-lifecycle groundwork stand.

Decision

The slogan bank, pickStartupSlogan, and the typewriter reveal are deleted. When welcome is unset the banner simply has no subtitle line — title and model/session detail only. The welcome config remains for deployments and fixtures that want a fixed subtitle, rendered frame-deterministically with no animation.
The startup animation is now the whole banner: HeaderComponent gains a revealWidth clip, and the header box wipes in left-to-right over ~24 frames at 15 ms (~360 ms total, ~60 fps), started after ui.start() succeeds and cleared through the same detachListeners path the typewriter used. stopBannerReveal also resets the clip so a disposed-mid-sweep header re-renders whole.
The PTY smoke's boot marker changes from the typewriter cursor (▌) to the banner's top-right corner (╮), which only renders once the sweep completes.

Alternatives considered

Keep the animation as-is and only change the copy. Rejected: any fixed or rotating phrase re-read on every boot decays into wallpaper; the user's judgment was that the quotes themselves, not just their content, were wrong for the surface.

Animate per banner line (top-down) instead of a left-right sweep. Rejected: with only four lines the animation would have four visible steps — closer to a flicker than a reveal; the horizontal sweep uses the full terminal width for a smooth motion at the same total duration.

Character-level clipping via revealWidth on styled text. Adopted with truncateToWidth from pi-tui, the same ANSI-aware clipper the header already uses for width overflow, so the sweep cannot tear escape sequences.

Consequences

Boot output with welcome unset is again animation-dependent but no longer random: every boot sweeps the same banner. Configured welcomes (all snapshot/scripted fixtures, the Code Mode overlay) stay frame-deterministic and unchanged.
The STARTUP_SLOGANS/pickStartupSlogan exports are gone; no consumer outside the deleted tests referenced them.
The default banner is one line shorter (no subtitle), so PTY assertions anchored on banner geometry use the corner glyph rather than any subtitle text.

Testing

packages/ui/tui/tests/tui.spec.ts pins: the sweep completes to a full banner (both corners + title) and produced at least one clipped mid-sweep frame; a configured welcome renders verbatim with no clipped frames; the unset-welcome banner has no subtitle; and dispose clears the sweep's own interval handle. The PTY smoke boots on the ╮ completion marker across the tui-demo bin, the dsh CLI, and the personal-overlay scenarios. Verified live in tmux.

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