TUI: persistent top-right update banner (+ --fake-update testing ground)

[plombeer31]

What

A persistent update strip in the top-right corner of the status bar, shown whenever a newer release exists, that also narrates the install once accepted:

   R U N                                                      new version v9.9.9 available   Update
   R U N                                                          updating to v9.9.9 — do not close
   R U N                                                       updated to v9.9.9 — restart to apply

The existing startup modal (y = update now · n / Esc = skip) is untouched. What changes is what happens around it: skipping no longer erases all trace of the update, and accepting no longer leaves the corner silent while the installer works.

Design

• Inverse-video (SGR 7), not a hand-picked color: the strip is by construction the opposite of whatever background the palette/terminal uses, so it is distinguishable on every theme without ever blinking or animating. Update is additionally accent-tinted + bold so the actionable cell reads as the button.
• Non-intrusive: static, claims no keys, sits in the corner the eye only visits deliberately. The modal remains the keyboard route.
• Clicking Update just works — including while the startup modal is still open. The modal raises the mouse floor to the modal rung, so the button registers on that rung too; a click there is exactly the modal's y (same onUpdateConfirmed → runUpdate() path, including its refusal while a turn is in flight), so answering the offer from the corner is the same decision, not a bypass.
• Lifecycle: raised by update_available; survives update_dismissed; shows updating to vX — do not close while the installer runs; updated to vX — restart to apply once it lands; returns to the offer — the retry path — after a failed install.
• Degrades instead of wrapping the one-row bar (Ink wraps rather than clips), per phase: new version v9.9.9 available [Update] → v9.9.9 [Update] → [Update] → nothing; updating to v9.9.9 — do not close → updating — do not close → updating…. Verified live at 100/70/52/46/42 columns.

Testing ground

atomic-agent tui --fake-update 9.9.9

(from a checkout: npm run build && node dist/cli/index.js tui --fake-update 9.9.9)

The flag pretends that version is on GitHub Releases: the real check is bypassed (a dev build fails canSelfUpdate anyway), and accepting — via the modal's y or the banner's Update — walks the same event sequence the real installer emits (started → feed lines → finished ok) on a watchable timeline, without ever running install.sh. The whole arc is on show: offer, click-through-the-modal, do-not-close strip, restart prompt; the post-update restart re-execs the same dev command, so nothing on the machine is ever replaced. --fake-update v9.9.9 also works; a missing/flag-shaped value is a usage error. Advertised in tui --help.

Tests

• update-banner.test.tsx — offer/running/done phase texts, per-phase degradation ladders, disappearance below the minimum, plan-never-exceeds-budget sweep across all phases.
• status-bar-update.test.tsx — banner shown on offer, survives modal dismissal, "do not close" while running (button gone), restart hint when done, retry offer after failure, absent with no offer, right-edge pinning, bar stays one row.
• Reducer: update_available raises modal+banner, update_dismissed clears only the modal, repeat offers during a run stay ignored.
• tui-args: --fake-update parsing (default null, v-prefix tolerated, missing value refused, in --help).

Full src/tui suite: 246 files / 2658 tests green (plus this machine's known pre-existing llama-server spawn-EACCES artifact, unrelated). Also verified in a real PTY: inverse attribute present on the whole strip, SGR mouse click on Update fires with the startup modal still on screen, the running and done strips render at the right moments, and the banner survives n.