aiti-msg-nav

❝ For chat histories thousands of stories tall, the elevator beats the stairs. ❞

A vertical scroll navigation bar on the right side of the message area, with four buttons:

• ⏫ To earliest: scroll to the top of the message container (triggers core lazy pagination → older messages load automatically while the viewport is held)

• ▲ Previous user input: from the viewport top boundary, find the previous user message and smooth-scroll to its upper edge (-24px margin)

• ▼ Next user input: same as above, searching downward for the next one

• ⏬ To latest: scroll to the bottom of the container; long-press keeps the screen awake (Screen Wake Lock API, active during agentRunning, auto-degrades when unsupported)

• Pure frontend extension: originally pi-web's built-in ScrollToolbar, extracted wholesale into an extension — core keeps only a chatOverlay slot mount point, with all interaction/positioning/scroll logic in the client bundle, working off two DOM contracts ([data-chat-scroll] scroll container / [data-chat-msg-role] message nodes), zero server APIs.

• Depends on core lazy pagination: scrolling to the top triggers the sentinel → core automatically loads older messages and holds the viewport; when "to earliest" has already hit the bottom of loaded history, it retries with a delay at the top of the container.

• User message positioning: linear scan to find the anchor (getBoundingClientRect relative to the container top + scrollTop; scrollTop + 8 is the viewport-top decision boundary).

• Drag to reposition: the whole nav bar can be dragged anywhere in the message area (persisted in localStorage pi-scroll-toolbar-pos, same key as the old built-in version so user habits carry over).

Feature management (extman)

feature	Type	Default	Notes
show.toolbar	boolean	on	Master switch (off = the nav bar isn't rendered)
behavior.keepAwake	boolean	on	Long-press "to latest" keeps the screen awake (Screen Wake Lock API, auto-degrades when unsupported)

Related extensions

• aiti-msg-anchor (message anchor banner): same chatOverlay slot, same set of DOM contracts — anchor is a top banner, nav is a right-side button column, complementary layouts; when both are on, watch for potential overlap at the top-right edge (both are absolutely positioned to the message column's right edge).