feat(sproutclaw): modularize webui, extensions, and agent config layout

Restructure local extensions into per-feature directories, split WebUI
into backend modules with slash commands and systemd support, and track
prompts/skills under .pi/agent for portable Gitea deployment.

Co-authored-by: Cursor <cursoragent@cursor.com>

.pi/agent/extensions/webui/backend/settings/extensions-paths.ts

@@ -0,0 +1,102 @@
+import { existsSync, readFileSync } from "node:fs";
+import { join, relative, resolve, sep } from "node:path";
+
+export function readConfiguredNpmPackageNames(settingsPath: string): Set<string> {
+  const names = new Set<string>();
+  if (!existsSync(settingsPath)) return names;
+
+  try {
+    const raw = JSON.parse(readFileSync(settingsPath, "utf8"));
+    const packages = raw?.packages;
+    if (!Array.isArray(packages)) return names;
+
+    for (const entry of packages) {
+      const source = typeof entry === "string" ? entry : entry?.source;
+      if (typeof source === "string" && source.startsWith("npm:")) {
+        const name = source.slice("npm:".length).trim();
+        if (name) names.add(name);
+      }
+    }
+  } catch {
+    /* ignore invalid settings */
+  }
+
+  return names;
+}
+
+export function extractNpmPackageNameFromPath(nodeModulesRoot: string, pathValue: string): string | null {
+  if (!pathValue) return null;
+
+  const root = resolve(nodeModulesRoot);
+  const normalized = resolve(pathValue);
+  if (normalized !== root && !normalized.startsWith(`${root}${sep}`)) {
+    return null;
+  }
+
+  const rel = relative(root, normalized);
+  const parts = rel.split(sep).filter(Boolean);
+  if (parts.length === 0) return null;
+  if (parts[0].startsWith("@") && parts.length >= 2) {
+    return `${parts[0]}/${parts[1]}`;
+  }
+  return parts[0] || null;
+}
+
+export function isLocalAgentExtension(pathValue: string, agentExtensionsDir: string): boolean {
+  if (!pathValue) return false;
+  const resolved = resolve(pathValue);
+  const root = resolve(agentExtensionsDir);
+  return resolved === root || resolved.startsWith(`${root}${sep}`);
+}
+
+export function isConfiguredNpmExtension(
+  pathValue: string,
+  nodeModulesRoot: string,
+  configuredPackages: Set<string>,
+): boolean {
+  const packageName = extractNpmPackageNameFromPath(nodeModulesRoot, pathValue);
+  return packageName !== null && configuredPackages.has(packageName);
+}
+
+export function getExtensionCategoryFromPath(
+  pathValue: string,
+  agentExtensionsDir: string,
+  nodeModulesRoot: string,
+  configuredPackages: Set<string>,
+): "local" | "npm" | null {
+  if (isConfiguredNpmExtension(pathValue, nodeModulesRoot, configuredPackages)) {
+    return "npm";
+  }
+  if (isLocalAgentExtension(pathValue, agentExtensionsDir)) {
+    return "local";
+  }
+  return null;
+}
+
+export function resolveNpmSource(pathValue: string, nodeModulesRoot: string, fallbackSource: string): string {
+  if (fallbackSource.startsWith("npm:")) return fallbackSource;
+  const packageName = extractNpmPackageNameFromPath(nodeModulesRoot, pathValue);
+  return packageName ? `npm:${packageName}` : fallbackSource;
+}
+
+export function readNpmPackageVersion(
+  nodeModulesRoot: string,
+  pathValue: string,
+  source: string,
+): string | undefined {
+  let packageName = extractNpmPackageNameFromPath(nodeModulesRoot, pathValue);
+  if (!packageName && source.startsWith("npm:")) {
+    packageName = source.slice("npm:".length).trim() || null;
+  }
+  if (!packageName) return undefined;
+
+  const pkgJsonPath = join(nodeModulesRoot, packageName, "package.json");
+  if (!existsSync(pkgJsonPath)) return undefined;
+
+  try {
+    const raw = JSON.parse(readFileSync(pkgJsonPath, "utf8")) as { version?: unknown };
+    return typeof raw.version === "string" && raw.version.trim() ? raw.version.trim() : undefined;
+  } catch {
+    return undefined;
+  }
+}