Overhaul Feynman harness: streamline agents, prompts, and extensions

Remove legacy chains, skills, and config modules. Add citation agent,
SYSTEM.md, modular research-tools extension, and web-access layer.
Add ralph-wiggum to Pi package stack for long-running loops.

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

extensions/research-tools/shared.ts

@@ -0,0 +1,46 @@
+import { readFileSync } from "node:fs";
+import { homedir } from "node:os";
+import { dirname, resolve as resolvePath } from "node:path";
+import { fileURLToPath } from "node:url";
+
+export const APP_ROOT = resolvePath(dirname(fileURLToPath(import.meta.url)), "..", "..");
+
+export const FEYNMAN_VERSION = (() => {
+	try {
+		const pkg = JSON.parse(readFileSync(resolvePath(APP_ROOT, "package.json"), "utf8")) as { version?: string };
+		return pkg.version ?? "dev";
+	} catch {
+		return "dev";
+	}
+})();
+
+export const FEYNMAN_AGENT_LOGO = [
+	"███████╗███████╗██╗   ██╗███╗   ██╗███╗   ███╗ █████╗ ███╗   ██╗",
+	"██╔════╝██╔════╝╚██╗ ██╔╝████╗  ██║████╗ ████║██╔══██╗████╗  ██║",
+	"█████╗  █████╗   ╚████╔╝ ██╔██╗ ██║██╔████╔██║███████║██╔██╗ ██║",
+	"██╔══╝  ██╔══╝    ╚██╔╝  ██║╚██╗██║██║╚██╔╝██║██╔══██║██║╚██╗██║",
+	"██║     ███████╗   ██║   ██║ ╚████║██║ ╚═╝ ██║██║  ██║██║ ╚████║",
+	"╚═╝     ╚══════╝   ╚═╝   ╚═╝  ╚═══╝╚═╝     ╚═╝╚═╝  ╚═╝╚═╝  ╚═══╝",
+];
+
+export const FEYNMAN_RESEARCH_TOOLS = [
+	"alpha_search",
+	"alpha_get_paper",
+	"alpha_ask_paper",
+	"alpha_annotate_paper",
+	"alpha_list_annotations",
+	"alpha_read_code",
+	"session_search",
+	"preview_file",
+];
+
+export function formatToolText(result: unknown): string {
+	return typeof result === "string" ? result : JSON.stringify(result, null, 2);
+}
+
+export function getFeynmanHome(): string {
+	const agentDir = process.env.FEYNMAN_CODING_AGENT_DIR ??
+		process.env.PI_CODING_AGENT_DIR ??
+		resolvePath(homedir(), ".feynman", "agent");
+	return dirname(agentDir);
+}