arcrun — AI workflow execution engine (clean history)

Self-hosted 開源：WASM 零件 + recipe + cypher-executor，跑在你自己的 Cloudflare。

此為重建的乾淨歷史起點（移除曾誤 commit 的 GCP SA 金鑰，舊歷史保留在
richblack/arcrun 與本地 backup 分支）。含：
- acr init --self-hosted installer（建 KV/R2 + codeload 拉預編譯 wasm + wrangler deploy + seed recipe）
- recipe push 把關（資料外流提醒 + 打通檢查）
- 19 個正當零件預編譯 wasm（claude_api/km_writer/kbdb_upsert_block 排除：違反 DECISIONS §1）
- CLI / cypher-executor / registry / 完整 SDD

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

cypher-executor/src/lib/recipe-loader.ts

@@ -0,0 +1,50 @@
+/**
+ * Prompt recipe loader：從 RECIPES KV 抓 prompt_recipe 定義並驗證
+ * SDD: matrix/arcrun/.agents/specs/recipe-system/design.md Phase 1.3
+ *
+ * KV key 格式：prompt_recipe:{name}
+ * KV value：JSON 字串（不用 YAML，避免引入 yaml parser 進 worker）
+ */
+
+import { PromptRecipeSchema, type PromptRecipe } from './prompt-recipe-schema';
+
+type KvBinding = { get: (key: string) => Promise<string | null> };
+
+export class RecipeLoadError extends Error {
+  constructor(message: string, public readonly recipe: string) {
+    super(message);
+  }
+}
+
+/** 從 RECIPES KV 抓 + parse + validate */
+export async function loadPromptRecipe(
+  recipeRef: string, // 完整 key 如 "prompt_recipe:wiki_synthesis"，或裸名 "wiki_synthesis"
+  recipesKv: KvBinding,
+): Promise<PromptRecipe> {
+  const key = recipeRef.startsWith('prompt_recipe:')
+    ? recipeRef
+    : `prompt_recipe:${recipeRef}`;
+
+  const raw = await recipesKv.get(key);
+  if (!raw) {
+    throw new RecipeLoadError(`找不到 recipe: ${key}`, key);
+  }
+
+  let parsed: unknown;
+  try {
+    parsed = JSON.parse(raw);
+  } catch (e) {
+    throw new RecipeLoadError(
+      `recipe ${key} 不是合法 JSON: ${e instanceof Error ? e.message : String(e)}`,
+      key,
+    );
+  }
+
+  const result = PromptRecipeSchema.safeParse(parsed);
+  if (!result.success) {
+    const issues = result.error.issues.map((i) => `${i.path.join('.')}: ${i.message}`).join('; ');
+    throw new RecipeLoadError(`recipe ${key} schema 驗證失敗: ${issues}`, key);
+  }
+
+  return result.data;
+}