feat: add live-cycling LSP completion

docs/editing.md

@@ -29,6 +29,7 @@ Default controls and editing behavior. For custom bindings, see [configuration](
 | Visual | Cursor/word motions and `n`/`N` extend every selection; `y` copies; `d`/`x`/Delete cuts; `c` changes; `v`/`V` switches shape, the same selector or Esc cancels |
 | Visual | Ctrl+l splits touched rows into Normal carets at first nonblank; Ctrl+n adds the next occurrence; Ctrl+s skips the primary occurrence; Ctrl+a selects all occurrences |
 | Insert | Type, Enter, Tab, Backspace/Delete, arrows, Home/End at every caret; Esc returns to Normal, retaining carets |
+| Insert | Ctrl+n requests completion at the primary caret or cycles next; Ctrl+j/k cycles next/previous while completion is open |
 | Command | Enter executes; Backspace edits; Esc cancels |
 | Search | Type a literal query; Enter finds the next match; Backspace edits; Esc cancels |
 
@@ -36,6 +37,14 @@ Default controls and editing behavior. For custom bindings, see [configuration](
 
 `gt`/`gb` move every caret to the first nonblank grapheme on the first/last row, including the empty final row after a trailing newline. Duplicate carets and overlapping Visual selections normalize as usual. Both Visual shapes retain their anchors and extend to the destination. These motions do not edit text or add undo history; count prefixes are consumed rather than interpreted as line numbers. `g` waits for its second key, and Escape cancels only the pending prefix. In Insert and command/search prompts, `gt`/`gb` remain literal text.
 
+## Manual LSP completion
+
+With an enabled server that provides completion, Ctrl+n in Insert requests candidates at the **primary caret only**. The first candidate is inserted immediately and a small list appears near the caret; Ctrl+n or Ctrl+j cycles forward, Ctrl+k backward, with wraparound. There is no acceptance step. The **Original text** row restores the document and carets from before the result was shown, including any additional edits. Completion never broadcasts a candidate to secondary carets: they are preserved and translated through each chosen edit.
+
+Every candidate is applied from that same immutable original document, not on top of the previous candidate. A candidate's primary replacement and additional text edits are one atomic change. Every other key closes the list and performs its ordinary action: typing continues at the carets, Enter inserts a newline, Tab inserts a literal tab, and Escape returns to Normal retaining the displayed candidate. There is no automatic popup or snippet expansion. Empty, unsupported, or invalid results leave the document unchanged and report a message.
+
+Cycling creates no separate undo entries. Only the final chosen edits join the existing Insert undo group; choosing Original text adds no completion edit. Undo restores that group, and dot repeats the final resolved completion edits rather than requests or intermediate candidates. The list stays inside the document text workspace, does not cover the gutter or explorer, and never takes the hardware cursor. Wheel input over it is consumed without choosing a candidate.
+
 ## Word motions
 
 Word motions separate runs of Unicode letters/numbers/underscore from runs of punctuation or emoji. Classification uses each grapheme's first character; combining sequences and ZWJ emoji stay intact. WORD motions treat any non-whitespace run as one WORD.
@@ -114,7 +123,7 @@ Paste is backend input: it is ignored in Normal, Command, Search, and Visual mod
 
 Mouse-wheel up/down scrolls the document view three rows per event without moving the primary or secondary carets, changing selections, or editing text. The caret may scroll offscreen; its terminal cursor is hidden until visible again. Navigation (including a motion blocked at the document boundary), editing, or buffer navigation restores caret-following. Idle updates and resizing preserve a wheel-scrolled view, clamped to the document.
 
-Wheel input over a hover popup or floating/docked file explorer scrolls that panel instead. Explorer scrolling preserves the selected file, filter, and keyboard focus; keyboard input resumes selection-following. An offscreen selected entry has no browsing cursor, while the filter input keeps its own cursor. Command palettes and startup notices consume wheel input without scrolling the background. Mouse clicks and dragging are not editing actions.
+Wheel input over a hover popup or floating/docked file explorer scrolls that panel instead. Explorer scrolling preserves the selected file, filter, and keyboard focus; keyboard input resumes selection-following. An offscreen selected entry has no browsing cursor, while the filter input keeps its own cursor. Completion lists, command palettes, and startup notices consume wheel input without scrolling the background or editing text. Mouse clicks and dragging are not editing actions.
 
 ## Buffers