Initial import of NousResearch/hermes-agent

ui-tui/packages/hermes-ink/src/ink/components/CursorAdvanceContext.ts

@@ -0,0 +1,35 @@
+import { createContext } from 'react'
+
+/**
+ * Notify Ink that the physical terminal cursor was advanced by an
+ * out-of-band stdout.write (e.g. the TextInput fast-echo path).
+ *
+ * This is a two-part notification — calling it updates both:
+ *
+ *   1. Ink's cached `displayCursor` (the basis log-update uses to
+ *      compute relative cursor moves for the next frame's preamble).
+ *      Without this, the next frame's preamble starts from a stale
+ *      parked position and the diff is rendered N cells offset.
+ *      This half is SKIPPED on alt-screen — every alt-screen frame
+ *      begins with CSI H which absolutely repositions the cursor, so
+ *      the relative-move basis is reset for free.
+ *
+ *   2. Ink's active `cursorDeclaration` (the target the cursor parks
+ *      at after every frame, set by `useDeclaredCursor`). Without
+ *      this, an unrelated component re-rendering before the deferred
+ *      React state catches up would publish a stale declaration and
+ *      visually undo the fast-echo's advance. This half applies to
+ *      BOTH main-screen and alt-screen — on alt-screen the cursor-
+ *      park branch in onRender emits an absolute CUP to
+ *      `rect.x + decl.relativeX`, so a stale declaration there is
+ *      still wrong even though displayCursor is skipped.
+ *
+ * `dx`/`dy` are deltas in terminal cells (positive = right/down,
+ * negative = left/up). The caller is responsible for ensuring the
+ * physical cursor really did move by that amount.
+ */
+export type CursorAdvanceNotifier = (dx: number, dy?: number) => void
+
+const CursorAdvanceContext = createContext<CursorAdvanceNotifier>(() => {})
+
+export default CursorAdvanceContext