Add SF-TUI extension main entry point.

Integrates footer rendering, working vibes, prompt history stash,
and git status tracking into unified TUI enhancement extension.

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

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

@@ -0,0 +1,84 @@
+/**
+ * SF-TUI — Unified TUI enhancements for Singularity Forge
+ *
+ * Features:
+ * - Rich footer: git branch, model, session cost, context usage
+ * - Working vibes: context-aware loading messages
+ * - Prompt history stash: Ctrl+Alt+H overlay with quick-pick
+ */
+
+import type { ExtensionAPI, ExtensionContext } from "@sf-run/pi-coding-agent";
+import { Key } from "@sf-run/pi-tui";
+import { isAutoActive } from "../sf/auto.js";
+import { openStashOverlay, readStash, pushStash, writeStash } from "./stash.js";
+import { renderFooter } from "./footer.js";
+import { setVibeForPrompt, setVibeForTool, clearVibe } from "./vibes.js";
+import { invalidateGitStatus } from "./git.js";
+
+export { setVibeForPrompt, setVibeForTool, clearVibe } from "./vibes.js";
+
+function installFooter(ctx: ExtensionContext): void {
+  if (!ctx.hasUI) return;
+  ctx.ui.setFooter((tui, theme, footerData) => {
+    return {
+      render: (width: number) => {
+        if (isAutoActive()) return [];
+        return renderFooter(theme, footerData, ctx, width);
+      },
+      invalidate: () => {},
+      dispose: () => {},
+    };
+  });
+}
+
+export default function sfTui(pi: ExtensionAPI): void {
+  const stash = readStash();
+  let wasAutoActive = false;
+
+  pi.on("session_start", async (_event, ctx) => {
+    if (!ctx.hasUI) return;
+
+    installFooter(ctx);
+
+    pi.registerShortcut(Key.ctrlAlt("h"), {
+      description: "Open prompt history stash",
+      handler: openStashOverlay,
+    });
+    pi.registerShortcut(Key.ctrlShift("h"), {
+      description: "Open prompt history stash (fallback)",
+      handler: openStashOverlay,
+    });
+
+    wasAutoActive = isAutoActive();
+  });
+
+  pi.on("before_agent_start", async (event) => {
+    const prompt = event.prompt?.trim();
+    if (prompt) {
+      pushStash(stash, prompt);
+      writeStash(stash);
+    }
+  });
+
+  pi.on("tool_call", async (event, ctx) => {
+    setVibeForTool(ctx, event.toolName, event.input);
+  });
+
+  pi.on("tool_result", async (_event, ctx) => {
+    invalidateGitStatus();
+    const autoNow = isAutoActive();
+    if (!autoNow && wasAutoActive) {
+      installFooter(ctx);
+    }
+    wasAutoActive = autoNow;
+  });
+
+  pi.on("agent_end", async (_event, ctx) => {
+    clearVibe(ctx);
+    const autoNow = isAutoActive();
+    if (!autoNow) {
+      installFooter(ctx);
+    }
+    wasAutoActive = autoNow;
+  });
+}