The terminal and history pagination both treated the model-visible surface as
the human transcript. A landed compaction replacement therefore erased the
conversation it summarized — messages the reader had already seen — and a
model-only replacement copy consumed a page's `maxMessages` quota, which could
also split a compaction's provenance from the replacement citing it.
`dsh-session` now exports the marker split `isAppendSurfaceEvent` /
`isReplacementSurfaceEvent`. The terminal replays append-origin surface events,
keeps a shadowed step's tool cards paired through its append-origin assistant
message, and renders one dim marker where a compaction landed; the checkpoint is
recognized through the compaction seam's `isCompactCheckpointSource` contract,
not the shape of the replacement. `session.history` counts only append-origin
human messages. Everything model-facing keeps reading `session.surface`.
Consolidates the personal dsh-tui customizations (module split into
components/session/extension, prompt template + running-glyph indicator,
copyable transcript, tool-card headers, timing placement, XML tool output,
status/footer rework) and ports upstream's model reasoning-effort selector
(Shift+Tab effort cycling, effort-aware /model, footer, and /status) onto
the personal module layout.
Squashes three linearized steps (feat/tui-startup, feat/banner-reveal,
feat/remove-banner): the banner experiment converged on removing the
startup banner entirely; later commits restore it borderless and add the
brand gradient.
