humanspeak / svelte-virtual-chat / 28094743435

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feat(chat): smooth scroll to bottom on new messages (#37)

* build(deps): bump dependencies

- @sveltejs/kit 2.65.1 -> 2.66.0 (root + docs)
- @types/node 25 -> 26, @testing-library/svelte 5.3 -> 5.4 (root)
- @humanspeak/svelte-motion 0.7.0 -> 0.7.3, @lucide/svelte 1.18 -> 1.21,
  @sveltejs/adapter-cloudflare 7.2.8 -> 7.2.9, wrangler 4.100 -> 4.103 (docs)
- regenerate docs worker-configuration.d.ts for wrangler bump

* build(deps): pin svelte 5.56.4 to fix esrap optional-param build break

esrap@2.2.12 began emitting the TypeScript optional-parameter marker
(`?`) into generated code, which Svelte <=5.56.3 failed to strip,
producing invalid JS like `(options?) =>` and breaking `vite build`
(rolldown PARSE_ERROR). The recent dependency bumps pulled esrap to
2.2.12, exposing the latent compiler bug.

- bump svelte to ^5.56.4 (root + docs), which strips the marker
  (sveltejs/svelte#18448)
- exclude svelte from minimumReleaseAge so 5.56.4 installs during its
  48h publish cooldown

* test(chat): add failing spec for smooth scroll-to-bottom on growth

Captures the desired behavior: when following the bottom and content
grows by a discrete amount, the viewport should ease toward the new
bottom over several frames instead of snapping in one.

Samples scrollTop per animation frame in the append world. After the
content height settles, a snap lands at the bottom in a single step;
the spec requires multiple increasing steps. Currently red — drives
the smooth-scroll implementation.

* feat(chat): ease to the bottom when new messages arrive while following

Replace the instant snap-to-bottom with a per-frame easing animation so
new messages slide into view instead of jumping. The loop re-reads
geometry each frame, so it tracks content that is still growing.

Scoped to stay safe and avoid regressions:
- only eases on a real message-count increase; height/measurement
  settling, streaming token growth, and mount positioning jump instantly
- only eases moderate dista... (continued)

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