refactor(eve): stop hand-maintaining what the dev TUI already knows

.changeset/tui-derived-constants.md

@@ -0,0 +1,5 @@
+---
+"eve": patch
+---
+
+Derive the dev TUI's slash-command suggestion window from the command registry instead of a hand-maintained constant, and collapse the duplicated cursor step in the terminal line-wrap loop.

packages/eve/src/cli/dev/tui/command-typeahead.test.ts

@@ -172,7 +172,7 @@ describe("renderCommandSuggestions", () => {
     const many = Array.from({ length: 14 }, (_, index) => spec(`command-${index}`));
     const state = { ...typeaheadFor(many, "/"), selectedIndex: 13 };
     const rows = renderCommandSuggestions(state, theme, 80).map(stripAnsi);
-    expect(rows).toHaveLength(11);
+    expect(rows).toHaveLength(PROMPT_COMMANDS.length);
     expect(rows.some((row) => row.includes("command-13"))).toBe(true);
     expect(rows.some((row) => row.includes("command-0"))).toBe(false);
     expect(rows.some((row) => row.includes("commands, showing"))).toBe(false);
@@ -181,7 +181,7 @@ describe("renderCommandSuggestions", () => {
   it("shows the first window of the command registry on a bare slash", () => {
     const state = typeaheadFor(PROMPT_COMMANDS, "/");
     const rows = renderCommandSuggestions(state, theme, 80).map(stripAnsi);
-    expect(rows).toHaveLength(Math.min(PROMPT_COMMANDS.length, 10));
+    expect(rows).toHaveLength(PROMPT_COMMANDS.length);
     expect(rows[0]).toContain("/help");
   });
 

packages/eve/src/cli/dev/tui/command-typeahead.ts

@@ -7,17 +7,17 @@
  */
 
 import type { PromptCommandSpec } from "./prompt-commands.js";
+import { PROMPT_COMMANDS } from "./prompt-commands.js";
 import { sliceVisible, visibleLength } from "#cli/ui/terminal-text.js";
 import type { Theme } from "./theme.js";
 import { renderCursorRow } from "#setup/cli/option-row.js";
 
 /**
  * The typeahead keeps the list scannable; extra matches window around the
- * cursor. Sized to hold the full command registry so a bare `/` never scrolls
- * a command (e.g. `/exit`) out of view — windowing is for longer future lists.
- * Keep this >= the number of entries in `PROMPT_COMMANDS`.
+ * cursor. Derived from the registry so a bare `/` never scrolls a command
+ * (e.g. `/exit`) out of view — windowing is for longer future lists.
  */
-const MAX_VISIBLE_SUGGESTIONS = 11;
+const MAX_VISIBLE_SUGGESTIONS = PROMPT_COMMANDS.length;
 
 export interface CommandTypeaheadState {
   /** The prompt text the matches were derived from. */

packages/eve/src/cli/ui/terminal-text.test.ts

@@ -61,6 +61,11 @@ describe("editable input geometry", () => {
     expect(wrapVisibleLine("\x1b[31m🇺🇸\x1b[0m", 1)).toEqual(["\x1b[31m🇺🇸\x1b[0m"]);
   });
 
+  it("keeps an empty line as one empty row", () => {
+    expect(wrapVisibleLine("", 10)).toEqual([""]);
+    expect(wrapVisibleLine("", 0)).toEqual([""]);
+  });
+
   it("word-wraps on the last space that fits and collapses the break whitespace", () => {
     expect(wrapVisibleLine("alpha beta gamma", 10)).toEqual(["alpha beta", "gamma"]);
     expect(wrapVisibleLine("alpha  beta   gamma", 6)).toEqual(["alpha", "beta", "gamma"]);

packages/eve/src/cli/ui/terminal-text.ts

@@ -2,8 +2,8 @@ import { graphemes } from "#shared/text-boundaries.js";
 
 const ansiEscape = String.fromCharCode(27);
 
-export const ansiPattern = new RegExp(`${ansiEscape}\\[[0-?]*[ -/]*[@-~]`, "g");
-export const ansiPrefixPattern = new RegExp(`^${ansiEscape}\\[[0-?]*[ -/]*[@-~]`);
+const ansiPattern = new RegExp(`${ansiEscape}\\[[0-?]*[ -/]*[@-~]`, "g");
+const ansiPrefixPattern = new RegExp(`^${ansiEscape}\\[[0-?]*[ -/]*[@-~]`);
 const emojiPresentationPattern = /\p{Emoji_Presentation}/u;
 const extendedPictographicPattern = /\p{Extended_Pictographic}/u;
 const keycapPattern = /^[#*0-9]\u{fe0f}?\u{20e3}$/u;
@@ -182,10 +182,6 @@ export function wrapVisibleLine(line: string, width: number): string[] {
     return [line];
   }
 
-  if (line.length === 0) {
-    return [""];
-  }
-
   const units = terminalTextUnits(line);
   let remainingWidth = 0;
   for (const unit of units) remainingWidth += unit.width;
@@ -194,25 +190,24 @@ export function wrapVisibleLine(line: string, width: number): string[] {
   let unitIndex = 0;
   let charOffset = 0;
 
-  const advanceTo = (targetOffset: number): void => {
-    while (charOffset < targetOffset && unitIndex < units.length) {
-      const unit = units[unitIndex]!;
-      charOffset += unit.text.length;
-      remainingWidth -= unit.width;
-      unitIndex += 1;
-    }
+  // The cursor moves one unit at a time: past the row just emitted, then past
+  // the whitespace the break consumed.
+  const consume = (): void => {
+    const unit = units[unitIndex]!;
+    charOffset += unit.text.length;
+    remainingWidth -= unit.width;
+    unitIndex += 1;
   };
 
   while (remainingWidth > width) {
     const breakAt = findVisibleBreakPoint(units, unitIndex, width);
     lines.push(line.slice(charOffset, charOffset + breakAt).trimEnd());
-    advanceTo(charOffset + breakAt);
+    const rowEnd = charOffset + breakAt;
+    while (charOffset < rowEnd && unitIndex < units.length) consume();
     while (unitIndex < units.length) {
       const unit = units[unitIndex]!;
       if (unit.ansi || unit.text.trimStart().length > 0) break;
-      charOffset += unit.text.length;
-      remainingWidth -= unit.width;
-      unitIndex += 1;
+      consume();
     }
   }
 
@@ -247,7 +242,7 @@ function findVisibleBreakPoint(
   return offset;
 }
 
-export function codePointWidth(codePoint: number): number {
+function codePointWidth(codePoint: number): number {
   if (codePoint === 0x09) {
     return 4;
   }