Add stash utility for TUI prompt history.

Provides shared stash management functions and overlay UI for browsing
and selecting previous prompts. Supports 1-9 quick picking.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/resources/extensions/sf-tui/stash.ts

@@ -0,0 +1,183 @@
+import type { ExtensionContext, Theme } from "@sf-run/pi-coding-agent";
+import { truncateToWidth, visibleWidth, matchesKey, Key } from "@sf-run/pi-tui";
+import { existsSync, readFileSync, writeFileSync, mkdirSync } from "node:fs";
+import { join, dirname } from "node:path";
+import { homedir } from "node:os";
+
+const LIMIT = 20;
+
+interface Data {
+  version: number;
+  history: string[];
+}
+
+function stashPath(): string {
+  return join(homedir(), ".sf", "agent", "prompt-history.json");
+}
+
+export function readStash(): string[] {
+  try {
+    const path = stashPath();
+    if (!existsSync(path)) return [];
+    const d = JSON.parse(readFileSync(path, "utf-8")) as Data;
+    return d.history.filter((h): h is string => typeof h === "string" && h.trim().length > 0);
+  } catch {
+    return [];
+  }
+}
+
+export function writeStash(history: string[]): void {
+  try {
+    const path = stashPath();
+    mkdirSync(dirname(path), { recursive: true });
+    writeFileSync(
+      path,
+      JSON.stringify({ version: 1, history: history.slice(0, LIMIT) }, null, 2) + "\n",
+      "utf-8",
+    );
+  } catch {
+    /* non-fatal */
+  }
+}
+
+export function pushStash(history: string[], text: string): void {
+  const t = text.trim();
+  if (!t || history[0] === t) return;
+  history.unshift(t);
+  if (history.length > LIMIT) {
+    history.length = LIMIT;
+  }
+}
+
+function preview(text: string, maxWidth: number): string {
+  const c = text.replace(/\s+/g, " ").trim();
+  return c ? truncateToWidth(c, maxWidth, "…") : "(empty)";
+}
+
+class StashOverlay {
+  private tui: { requestRender: () => void };
+  private theme: Theme;
+  private done: (s: string | null) => void;
+  private items: string[];
+  private sel = 0;
+  private cacheW = 0;
+  private cacheL: string[] = [];
+
+  constructor(
+    tui: { requestRender: () => void },
+    theme: Theme,
+    items: string[],
+    done: (s: string | null) => void,
+  ) {
+    this.tui = tui;
+    this.theme = theme;
+    this.items = items;
+    this.done = done;
+  }
+
+  handleInput(data: string): void {
+    if (matchesKey(data, Key.escape) || matchesKey(data, Key.ctrl("c"))) {
+      this.done(null);
+      return;
+    }
+    if (matchesKey(data, Key.return) || matchesKey(data, Key.enter)) {
+      this.done(this.items[this.sel] ?? null);
+      return;
+    }
+    if (matchesKey(data, Key.down) || data === "j") {
+      this.sel = Math.min(this.items.length - 1, this.sel + 1);
+      this.invalidate();
+      this.tui.requestRender();
+      return;
+    }
+    if (matchesKey(data, Key.up) || data === "k") {
+      this.sel = Math.max(0, this.sel - 1);
+      this.invalidate();
+      this.tui.requestRender();
+      return;
+    }
+    if (data >= "1" && data <= "9") {
+      const idx = parseInt(data, 10) - 1;
+      if (idx >= 0 && idx < this.items.length) {
+        this.done(this.items[idx] ?? null);
+      }
+    }
+  }
+
+  invalidate(): void {
+    this.cacheW = 0;
+  }
+
+  render(width: number): string[] {
+    if (this.cacheW === width) return this.cacheL;
+
+    const th = this.theme;
+    const bw = Math.min(84, width - 4);
+    const iw = bw - 4;
+
+    const pad = (s: string) => s + " ".repeat(Math.max(0, width - visibleWidth(s)));
+    const box = (s: string) => {
+      const len = visibleWidth(s);
+      return th.fg("dim", "│ ") + s + " ".repeat(Math.max(0, bw - 2 - len)) + th.fg("dim", " │");
+    };
+
+    const lines: string[] = [];
+    lines.push(pad(th.fg("dim", "╭" + "─".repeat(bw) + "╮")));
+    lines.push(pad(box(th.bold(th.fg("accent", "📜 Prompt History")))));
+    lines.push(pad(th.fg("dim", "├" + "─".repeat(bw) + "┤")));
+    lines.push(pad(box(th.fg("dim", "↑/jk navigate • 1-9 quick pick • Enter insert • Esc cancel"))));
+    lines.push(pad(box("")));
+
+    for (let i = 0; i < this.items.length; i++) {
+      const item = this.items[i]!;
+      const p = preview(item, iw - 8);
+      const ptr = i === this.sel ? th.fg("accent", "❯ ") : "  ";
+      const num = i < 9 ? th.fg("dim", `${i + 1}`) : " ";
+      const label = i === this.sel ? th.fg("accent", p) : p;
+      lines.push(pad(box(`${ptr}${num}. ${label}`)));
+    }
+
+    lines.push(pad(box("")));
+    lines.push(pad(th.fg("dim", "├" + "─".repeat(bw) + "┤")));
+    lines.push(pad(box(th.fg("dim", `${this.items.length} stashed prompts`))));
+    lines.push(pad(th.fg("dim", "╰" + "─".repeat(bw) + "╯")));
+    lines.push("");
+
+    this.cacheL = lines;
+    this.cacheW = width;
+    return lines;
+  }
+}
+
+export async function openStashOverlay(ctx: ExtensionContext): Promise<void> {
+  if (!ctx.hasUI) {
+    ctx.ui.notify("Prompt history requires interactive mode", "error");
+    return;
+  }
+  const items = readStash();
+  if (!items.length) {
+    ctx.ui.notify("No stashed prompts yet. Send a message to build history.", "info");
+    return;
+  }
+  const selected = await ctx.ui.custom<string | null>((tui, theme, _kb, done) => {
+    const o = new StashOverlay(tui, theme, items, done);
+    return {
+      render: (w) => o.render(w),
+      invalidate: () => o.invalidate(),
+      handleInput: (d) => o.handleInput(d),
+    };
+  }, {
+    overlay: true,
+    overlayOptions: {
+      width: "90%",
+      minWidth: 60,
+      maxHeight: "85%",
+      anchor: "center",
+      backdrop: true,
+    },
+  });
+  if (selected) {
+    ctx.ui.setEditorText(selected);
+    ctx.ui.notify("Inserted prompt from history", "info");
+  }
+}