feat(tui): add fuzzy search to model picker

- Add SearchableSelectList component with fuzzy filtering
- Integrate with /models command for quick model search
- Support up/down navigation while typing
- Uses pi-tui's fuzzyFilter for intelligent matching

src/tui/components/searchable-select-list.test.ts

@@ -0,0 +1,111 @@
+import { describe, expect, it } from "vitest";
+import { SearchableSelectList, type SearchableSelectListTheme } from "./searchable-select-list.js";
+
+const mockTheme: SearchableSelectListTheme = {
+  selectedPrefix: (t) => `[${t}]`,
+  selectedText: (t) => `**${t}**`,
+  description: (t) => `(${t})`,
+  scrollInfo: (t) => `~${t}~`,
+  noMatch: (t) => `!${t}!`,
+  searchPrompt: (t) => `>${t}<`,
+  searchInput: (t) => `|${t}|`,
+  matchHighlight: (t) => `*${t}*`,
+};
+
+const testItems = [
+  { value: "anthropic/claude-3-opus", label: "anthropic/claude-3-opus", description: "Claude 3 Opus" },
+  { value: "anthropic/claude-3-sonnet", label: "anthropic/claude-3-sonnet", description: "Claude 3 Sonnet" },
+  { value: "openai/gpt-4", label: "openai/gpt-4", description: "GPT-4" },
+  { value: "openai/gpt-4-turbo", label: "openai/gpt-4-turbo", description: "GPT-4 Turbo" },
+  { value: "google/gemini-pro", label: "google/gemini-pro", description: "Gemini Pro" },
+];
+
+describe("SearchableSelectList", () => {
+  it("renders all items when no filter is applied", () => {
+    const list = new SearchableSelectList(testItems, 5, mockTheme);
+    const output = list.render(80);
+
+    // Should have search prompt line, spacer, and items
+    expect(output.length).toBeGreaterThanOrEqual(3);
+    expect(output[0]).toContain("search");
+  });
+
+  it("filters items when typing", () => {
+    const list = new SearchableSelectList(testItems, 5, mockTheme);
+
+    // Simulate typing "gemini" - unique enough to narrow down
+    list.handleInput("g");
+    list.handleInput("e");
+    list.handleInput("m");
+    list.handleInput("i");
+    list.handleInput("n");
+    list.handleInput("i");
+
+    const selected = list.getSelectedItem();
+    expect(selected?.value).toBe("google/gemini-pro");
+  });
+
+  it("filters items with fuzzy matching", () => {
+    const list = new SearchableSelectList(testItems, 5, mockTheme);
+
+    // Simulate typing "gpt" which should match openai/gpt-4 models
+    list.handleInput("g");
+    list.handleInput("p");
+    list.handleInput("t");
+
+    const selected = list.getSelectedItem();
+    expect(selected?.value).toContain("gpt");
+  });
+
+  it("shows no match message when filter yields no results", () => {
+    const list = new SearchableSelectList(testItems, 5, mockTheme);
+
+    // Type something that won't match
+    list.handleInput("x");
+    list.handleInput("y");
+    list.handleInput("z");
+
+    const output = list.render(80);
+    expect(output.some((line) => line.includes("No matching"))).toBe(true);
+  });
+
+  it("navigates with arrow keys", () => {
+    const list = new SearchableSelectList(testItems, 5, mockTheme);
+
+    // Initially first item is selected
+    expect(list.getSelectedItem()?.value).toBe("anthropic/claude-3-opus");
+
+    // Press down arrow (escape sequence for down arrow)
+    list.handleInput("\x1b[B");
+
+    expect(list.getSelectedItem()?.value).toBe("anthropic/claude-3-sonnet");
+  });
+
+  it("calls onSelect when enter is pressed", () => {
+    const list = new SearchableSelectList(testItems, 5, mockTheme);
+    let selectedValue: string | undefined;
+
+    list.onSelect = (item) => {
+      selectedValue = item.value;
+    };
+
+    // Press enter
+    list.handleInput("\r");
+
+    expect(selectedValue).toBe("anthropic/claude-3-opus");
+  });
+
+  it("calls onCancel when escape is pressed", () => {
+    const list = new SearchableSelectList(testItems, 5, mockTheme);
+    let cancelled = false;
+
+    list.onCancel = () => {
+      cancelled = true;
+    };
+
+    // Press escape
+    list.handleInput("\x1b");
+
+    expect(cancelled).toBe(true);
+  });
+});

src/tui/components/searchable-select-list.ts

@@ -0,0 +1,199 @@
+import {
+  type Component,
+  fuzzyFilter,
+  Input,
+  isKeyRelease,
+  matchesKey,
+  type SelectItem,
+  type SelectListTheme,
+  truncateToWidth,
+} from "@mariozechner/pi-tui";
+
+export interface SearchableSelectListTheme extends SelectListTheme {
+  searchPrompt: (text: string) => string;
+  searchInput: (text: string) => string;
+  matchHighlight: (text: string) => string;
+}
+
+/**
+ * A select list with a search input at the top for fuzzy filtering.
+ */
+export class SearchableSelectList implements Component {
+  private items: SelectItem[];
+  private filteredItems: SelectItem[];
+  private selectedIndex = 0;
+  private maxVisible: number;
+  private theme: SearchableSelectListTheme;
+  private searchInput: Input;
+  private searchQuery = "";
+
+  onSelect?: (item: SelectItem) => void;
+  onCancel?: () => void;
+  onSelectionChange?: (item: SelectItem) => void;
+
+  constructor(items: SelectItem[], maxVisible: number, theme: SearchableSelectListTheme) {
+    this.items = items;
+    this.filteredItems = items;
+    this.maxVisible = maxVisible;
+    this.theme = theme;
+    this.searchInput = new Input();
+  }
+
+  private updateFilter() {
+    const query = this.searchInput.getValue().trim();
+    this.searchQuery = query;
+
+    if (!query) {
+      this.filteredItems = this.items;
+    } else {
+      this.filteredItems = fuzzyFilter(this.items, query, (item) => `${item.label} ${item.description ?? ""}`);
+    }
+
+    // Reset selection when filter changes
+    this.selectedIndex = 0;
+    this.notifySelectionChange();
+  }
+
+  setSelectedIndex(index: number) {
+    this.selectedIndex = Math.max(0, Math.min(index, this.filteredItems.length - 1));
+  }
+
+  invalidate() {
+    this.searchInput.invalidate();
+  }
+
+  render(width: number): string[] {
+    const lines: string[] = [];
+
+    // Search input line
+    const prompt = this.theme.searchPrompt("search: ");
+    const inputLines = this.searchInput.render(width - 8);
+    const inputText = inputLines[0] ?? "";
+    lines.push(`${prompt}${this.theme.searchInput(inputText)}`);
+    lines.push(""); // Spacer
+
+    // If no items match filter, show message
+    if (this.filteredItems.length === 0) {
+      lines.push(this.theme.noMatch("  No matching models"));
+      return lines;
+    }
+
+    // Calculate visible range with scrolling
+    const startIndex = Math.max(
+      0,
+      Math.min(this.selectedIndex - Math.floor(this.maxVisible / 2), this.filteredItems.length - this.maxVisible),
+    );
+    const endIndex = Math.min(startIndex + this.maxVisible, this.filteredItems.length);
+
+    // Render visible items
+    for (let i = startIndex; i < endIndex; i++) {
+      const item = this.filteredItems[i];
+      if (!item) continue;
+      const isSelected = i === this.selectedIndex;
+      let line = "";
+
+      if (isSelected) {
+        const prefixWidth = 2;
+        const displayValue = item.label || item.value;
+        if (item.description && width > 40) {
+          const maxValueWidth = Math.min(30, width - prefixWidth - 4);
+          const truncatedValue = truncateToWidth(displayValue, maxValueWidth, "");
+          const spacing = " ".repeat(Math.max(1, 32 - truncatedValue.length));
+          const descriptionStart = prefixWidth + truncatedValue.length + spacing.length;
+          const remainingWidth = width - descriptionStart - 2;
+          if (remainingWidth > 10) {
+            const truncatedDesc = truncateToWidth(item.description, remainingWidth, "");
+            line = this.theme.selectedText(`→ ${truncatedValue}${spacing}${truncatedDesc}`);
+          } else {
+            const maxWidth = width - prefixWidth - 2;
+            line = this.theme.selectedText(`→ ${truncateToWidth(displayValue, maxWidth, "")}`);
+          }
+        } else {
+          const maxWidth = width - prefixWidth - 2;
+          line = this.theme.selectedText(`→ ${truncateToWidth(displayValue, maxWidth, "")}`);
+        }
+      } else {
+        const displayValue = item.label || item.value;
+        const prefix = "  ";
+        if (item.description && width > 40) {
+          const maxValueWidth = Math.min(30, width - prefix.length - 4);
+          const truncatedValue = truncateToWidth(displayValue, maxValueWidth, "");
+          const spacing = " ".repeat(Math.max(1, 32 - truncatedValue.length));
+          const descriptionStart = prefix.length + truncatedValue.length + spacing.length;
+          const remainingWidth = width - descriptionStart - 2;
+          if (remainingWidth > 10) {
+            const truncatedDesc = truncateToWidth(item.description, remainingWidth, "");
+            line = `${prefix}${truncatedValue}${spacing}${this.theme.description(truncatedDesc)}`;
+          } else {
+            const maxWidth = width - prefix.length - 2;
+            line = `${prefix}${truncateToWidth(displayValue, maxWidth, "")}`;
+          }
+        } else {
+          const maxWidth = width - prefix.length - 2;
+          line = `${prefix}${truncateToWidth(displayValue, maxWidth, "")}`;
+        }
+      }
+      lines.push(line);
+    }
+
+    // Show scroll indicator if needed
+    if (this.filteredItems.length > this.maxVisible) {
+      const scrollInfo = `${this.selectedIndex + 1}/${this.filteredItems.length}`;
+      lines.push(this.theme.scrollInfo(`  ${scrollInfo}`));
+    }
+
+    return lines;
+  }
+
+  handleInput(keyData: string): void {
+    if (isKeyRelease(keyData)) return;
+
+    // Navigation keys
+    if (matchesKey(keyData, "up") || matchesKey(keyData, "ctrl+p")) {
+      this.selectedIndex = Math.max(0, this.selectedIndex - 1);
+      this.notifySelectionChange();
+      return;
+    }
+
+    if (matchesKey(keyData, "down") || matchesKey(keyData, "ctrl+n")) {
+      this.selectedIndex = Math.min(this.filteredItems.length - 1, this.selectedIndex + 1);
+      this.notifySelectionChange();
+      return;
+    }
+
+    if (matchesKey(keyData, "enter")) {
+      const item = this.filteredItems[this.selectedIndex];
+      if (item && this.onSelect) {
+        this.onSelect(item);
+      }
+      return;
+    }
+
+    if (matchesKey(keyData, "escape")) {
+      if (this.onCancel) {
+        this.onCancel();
+      }
+      return;
+    }
+
+    // Pass other keys to search input
+    const prevValue = this.searchInput.getValue();
+    this.searchInput.handleInput(keyData);
+    const newValue = this.searchInput.getValue();
+
+    if (prevValue !== newValue) {
+      this.updateFilter();
+    }
+  }
+
+  private notifySelectionChange() {
+    const item = this.filteredItems[this.selectedIndex];
+    if (item && this.onSelectionChange) {
+      this.onSelectionChange(item);
+    }
+  }
+
+  getSelectedItem(): SelectItem | null {
+    return this.filteredItems[this.selectedIndex] ?? null;
+  }
+}

src/tui/components/selectors.ts

@@ -1,10 +1,15 @@
 import { type SelectItem, SelectList, type SettingItem, SettingsList } from "@mariozechner/pi-tui";
-import { selectListTheme, settingsListTheme } from "../theme/theme.js";
+import { searchableSelectListTheme, selectListTheme, settingsListTheme } from "../theme/theme.js";
+import { SearchableSelectList } from "./searchable-select-list.js";
 
 export function createSelectList(items: SelectItem[], maxVisible = 7) {
   return new SelectList(items, maxVisible, selectListTheme);
 }
 
+export function createSearchableSelectList(items: SelectItem[], maxVisible = 7) {
+  return new SearchableSelectList(items, maxVisible, searchableSelectListTheme);
+}
+
 export function createSettingsList(
   items: SettingItem[],
   onChange: (id: string, value: string) => void,

src/tui/theme/theme.ts

@@ -5,6 +5,7 @@ import type {
   SettingsListTheme,
 } from "@mariozechner/pi-tui";
 import chalk from "chalk";
+import type { SearchableSelectListTheme } from "../components/searchable-select-list.js";
 
 const palette = {
   text: "#E8E3D5",
@@ -92,3 +93,14 @@ export const editorTheme: EditorTheme = {
   borderColor: (text) => fg(palette.border)(text),
   selectList: selectListTheme,
 };
+
+export const searchableSelectListTheme: SearchableSelectListTheme = {
+  selectedPrefix: (text) => fg(palette.accent)(text),
+  selectedText: (text) => chalk.bold(fg(palette.accent)(text)),
+  description: (text) => fg(palette.dim)(text),
+  scrollInfo: (text) => fg(palette.dim)(text),
+  noMatch: (text) => fg(palette.dim)(text),
+  searchPrompt: (text) => fg(palette.accentSoft)(text),
+  searchInput: (text) => fg(palette.text)(text),
+  matchHighlight: (text) => chalk.bold(fg(palette.accent)(text)),
+};

src/tui/tui-command-handlers.ts

@@ -7,7 +7,7 @@ import {
 import { normalizeAgentId } from "../routing/session-key.js";
 import { helpText, parseCommand } from "./commands.js";
 import type { ChatLog } from "./components/chat-log.js";
-import { createSelectList, createSettingsList } from "./components/selectors.js";
+import { createSearchableSelectList, createSelectList, createSettingsList } from "./components/selectors.js";
 import type { GatewayChatClient } from "./gateway-chat.js";
 import { formatStatusSummary } from "./tui-status-summary.js";
 import type {
@@ -72,7 +72,7 @@ export function createCommandHandlers(context: CommandHandlerContext) {
         label: `${model.provider}/${model.id}`,
         description: model.name && model.name !== model.id ? model.name : "",
       }));
-      const selector = createSelectList(items, 9);
+      const selector = createSearchableSelectList(items, 9);
       selector.onSelect = (item) => {
         void (async () => {
           try {