feat(auth): auth_static_key WASM primitive + host functions

- wasi-shim gains kv_get / crypto_decrypt / crypto_sign_rs256 host
  functions with strict boundary (ENCRYPTION_KEY never exits Worker).
- registry/components/auth_static_key: TinyGo impl for API-key /
  Bearer / Basic Auth recipes (80% of supported services).
- .component-builds/auth_static_key: independent Worker at
  auth-static-key.arcrun.dev, imports wasi-shim cross-directory.
- cypher-executor/auth-dispatcher routes static_key recipes to the
  new Worker instead of credential-injector TS.

Replaces TS credential injection per
.agents/specs/arcrun/credential-primitives-wasm Phase 1.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.component-builds/auth_static_key/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "arcrun-auth-static-key",
+  "version": "1.0.0",
+  "private": true,
+  "type": "module",
+  "dependencies": {
+    "hono": "^4.7.0"
+  },
+  "devDependencies": {
+    "@cloudflare/workers-types": "^4.20250408.0",
+    "typescript": "^5.4.0",
+    "wrangler": "^4.0.0"
+  }
+}

.component-builds/auth_static_key/src/index.ts

@@ -0,0 +1,83 @@
+/**
+ * arcrun auth_static_key Worker
+ *
+ * POST / → JSON input {action, api_key, service} → WASM (WASI preview1 stdin/stdout) → JSON output
+ *
+ * 方案 A:直接 import cypher-executor/src/lib/wasi-shim.ts 的 shim + host function factory,
+ * 確保 AES-GCM 解密邏輯只存在於一個檔案(rule 02 §2.2)。
+ *
+ * 安全邊界:
+ *   - api_key 經 stdin 傳進 WASM,同時綁到 host function 的 kv_get 做越權檢查
+ *   - ENCRYPTION_KEY 只存在於 host function 的 closure 中,不會進入 WASM 記憶體
+ */
+
+import componentWasm from '../component.wasm' assert { type: 'webassembly' };
+import { Hono } from 'hono';
+import { cors } from 'hono/cors';
+import {
+  createWasiShim,
+  createArcrunHostFunctions,
+  type ArcrunHostEnv,
+} from '../../../cypher-executor/src/lib/wasi-shim';
+
+type Env = ArcrunHostEnv;
+
+const app = new Hono<{ Bindings: Env }>();
+app.use('*', cors());
+
+app.get('/', (c) => c.json({ ok: true, component: 'auth_static_key' }));
+
+app.post('/', async (c) => {
+  let input: Record<string, unknown>;
+  try {
+    input = await c.req.json();
+  } catch {
+    return c.json({ success: false, error: 'request body must be JSON' }, 400);
+  }
+
+  const apiKey = typeof input.api_key === 'string' ? input.api_key : '';
+  if (!apiKey) {
+    return c.json({ success: false, error: 'api_key 必填' }, 400);
+  }
+
+  try {
+    const result = await runWasm(c.env, apiKey, input);
+    return c.json(result);
+  } catch (e) {
+    return c.json(
+      { success: false, error: e instanceof Error ? e.message : String(e) },
+      500,
+    );
+  }
+});
+
+export default app;
+
+// ── WASM runner ──────────────────────────────────────────────────────────────
+
+async function runWasm(env: Env, apiKey: string, input: unknown): Promise<unknown> {
+  const stdinData = JSON.stringify(input);
+  const hostFunctions = createArcrunHostFunctions(env, apiKey);
+  const shim = createWasiShim(stdinData, hostFunctions);
+
+  const instance = await WebAssembly.instantiate(
+    componentWasm as WebAssembly.Module,
+    shim.imports,
+  );
+  shim.setMemory(instance.exports.memory as WebAssembly.Memory);
+
+  const start = (instance.exports._start ?? instance.exports.main) as () => void;
+  if (typeof start !== 'function') {
+    throw new Error('WASM missing _start or main export');
+  }
+
+  try {
+    start();
+  } catch (e) {
+    if (!(e instanceof Error && e.message === 'wasm exit: 0')) throw e;
+  }
+
+  const stdout = shim.getStdout().trim();
+  if (!stdout) throw new Error('WASM component produced no output');
+  return JSON.parse(stdout);
+}

.component-builds/auth_static_key/tsconfig.json

@@ -0,0 +1,11 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "ES2022",
+    "moduleResolution": "bundler",
+    "lib": ["ES2022"],
+    "types": ["@cloudflare/workers-types"],
+    "strict": true,
+    "noEmit": true
+  }
+}

.component-builds/auth_static_key/wrangler.toml

@@ -0,0 +1,23 @@
+name = "arcrun-auth-static-key"
+main = "src/index.ts"
+compatibility_date = "2025-02-19"
+compatibility_flags = ["nodejs_compat"]
+
+[vars]
+COMPONENT_ID = "auth_static_key"
+
+[[routes]]
+pattern = "auth-static-key.arcrun.dev/*"
+zone_name = "arcrun.dev"
+
+# 與 cypher-executor/wrangler.toml 同一組 KV namespace
+[[kv_namespaces]]
+binding = "CREDENTIALS_KV"
+id = "e7f4320f88d343f187e35e3543dd74c9"
+
+[[kv_namespaces]]
+binding = "RECIPES"
+id = "9cf9db905c6241f78503199e58b2ffe0"
+
+# ENCRYPTION_KEY 透過 wrangler secret set 設定
+# wrangler secret put ENCRYPTION_KEY

cypher-executor/src/actions/auth-dispatcher.ts

@@ -0,0 +1,94 @@
+/**
+ * Auth Dispatcher
+ *
+ * 對需要認證的零件,在執行前 HTTP POST 到對應的 auth primitive Worker,
+ * 取回 auth_headers / auth_query / auth_body 合併進節點 context。
+ *
+ * 嚴格邊界(rule 02 §2.2):
+ *   - 本檔**不做**任何 credential 解密 / template 展開 / JWT 簽章
+ *   - 那些全部在 auth primitive WASM 零件內執行(透過 host function `crypto_decrypt` 等)
+ *   - 本檔只做「查 recipe 決定走哪個 primitive Worker」+「HTTP fetch 取回注入結果」
+ *
+ * 目前階段(Phase 2)接上 `auth_static_key` + `auth_service_account`,
+ * Phase 4(封測後)加 `auth_oauth2` / `auth_mtls`。
+ *
+ * 執行時機:graph-executor 在節點 runner 執行前呼叫,取回的 ctx 會:
+ *   1. 先試本 dispatcher(命中才 return enriched ctx)
+ *   2. 沒命中 fallback 到 `injectCredentials`(Phase 1.9 才刪除)
+ */
+
+import type { Bindings } from '../types';
+import { resolveAuthRecipe } from '../routes/recipes';
+import { wasmWorkerUrl } from '../lib/component-loader';
+
+/** 對應 Phase 1-4 會部署的 auth primitive Worker */
+const SUPPORTED_PRIMITIVES = new Set(['static_key', 'service_account']);
+
+/** auth primitive 本身的 componentId(避免自引用) */
+const AUTH_PRIMITIVE_IDS = new Set([
+  'auth_static_key',
+  'auth_service_account',
+  'auth_oauth2',
+  'auth_mtls',
+]);
+
+/**
+ * 試著對零件做 auth 注入。
+ * - 命中(有對應 auth recipe 且 primitive 已支援)→ 回傳注入後的 ctx
+ * - 未命中 → 回傳 null(呼叫端繼續跑舊路徑)
+ */
+export async function tryAuthDispatch(
+  componentId: string,
+  input: Record<string, unknown>,
+  env: Bindings,
+  apiKey: string,
+): Promise<Record<string, unknown> | null> {
+  if (AUTH_PRIMITIVE_IDS.has(componentId)) {
+    // auth primitive 本身不需要再做 auth
+    return null;
+  }
+
+  const recipe = await resolveAuthRecipe(componentId, env.RECIPES);
+  if (!recipe) return null;
+  if (!SUPPORTED_PRIMITIVES.has(recipe.primitive)) return null;
+
+  // 走新路徑:HTTP POST 到對應 auth primitive Worker
+  const primitiveUrl = wasmWorkerUrl(`auth_${recipe.primitive}`);
+  const res = await fetch(primitiveUrl, {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify({
+      action: 'authenticate',
+      api_key: apiKey,
+      service: componentId,
+    }),
+  });
+
+  if (!res.ok) {
+    const text = await res.text().catch(() => '');
+    throw new Error(
+      `auth primitive "${recipe.primitive}" 回傳 ${res.status}: ${text.slice(0, 200)}`,
+    );
+  }
+
+  const result = await res.json().catch(() => null) as {
+    success?: boolean;
+    error?: string;
+    auth_headers?: Record<string, string>;
+    auth_query?: Record<string, string>;
+    auth_body?: Record<string, string>;
+  } | null;
+
+  if (!result || result.success === false) {
+    throw new Error(
+      `auth primitive 失敗: ${result?.error ?? '未知錯誤'}`,
+    );
+  }
+
+  return {
+    ...input,
+    _auth_headers: result.auth_headers ?? {},
+    _auth_query: result.auth_query ?? {},
+    _auth_body: result.auth_body ?? {},
+  };
+}

cypher-executor/src/lib/wasi-shim.ts

@@ -7,6 +7,17 @@
  * Requirements: 3.1, 3.3
  */
 
+/**
+ * createArcrunHostFunctions 所需的最小 env 子集。
+ * 不直接依賴 cypher-executor 的 Bindings,讓 auth primitive Worker 這類
+ * 只綁 CREDENTIALS_KV / RECIPES / ENCRYPTION_KEY 的獨立 Worker 也能用。
+ */
+export interface ArcrunHostEnv {
+  CREDENTIALS_KV: KVNamespace;
+  RECIPES: KVNamespace;
+  ENCRYPTION_KEY: string;
+}
+
 const WASI_ESUCCESS = 0;
 const WASI_ENOSYS = 76;
 
@@ -29,10 +40,20 @@ export interface WasiShim {
 /**
  * Host function 注入介面
  * 讓 .wasm 零件能透過 host function 呼叫外部服務，而不需要網路 syscall
+ *
+ * 嚴格邊界：
+ * - encryption key 只在 `crypto_decrypt` host function 內部使用，永遠不傳給 WASM
+ * - `kv_get` 必須在 Worker 側檢查 key 前綴以防越權（見 auth-dispatcher.ts）
  */
 export interface WasiHostFunctions {
   /** HTTP 請求 host function：.wasm 呼叫此函數發出 HTTP 請求 */
   http_request?: (url: string, method: string, headers: string, body: string) => Promise<string>;
+  /** KV 讀取：key 前綴由 Worker 路由到對應 binding，並做越權檢查 */
+  kv_get?: (key: string) => Promise<string | null>;
+  /** AES-GCM 解密：encryption key 由 Worker 保管，不暴露給 WASM */
+  crypto_decrypt?: (encryptedB64: string, ivB64: string) => Promise<string>;
+  /** RS256 簽章：用 crypto.subtle 做 RSASSA-PKCS1-v1_5 + SHA-256 */
+  crypto_sign_rs256?: (data: Uint8Array, pkcs8: Uint8Array) => Promise<Uint8Array>;
 }
 
 /**
@@ -54,6 +75,18 @@ export function createWasiShim(stdinData: string, hostFunctions?: WasiHostFuncti
     return new DataView(memory.buffer);
   }
 
+  // 寫入結果到 WASM 的 outPtr buffer（host function 共用）
+  // 回傳 0 = 成功，1 = memory 不可用
+  function writeOut(buf: ArrayBuffer, outPtr: number, outLenPtr: number, data: Uint8Array): number {
+    try {
+      new Uint8Array(buf, outPtr, data.length).set(data);
+      new DataView(buf).setUint32(outLenPtr, data.length, true);
+      return 0;
+    } catch {
+      return 1;
+    }
+  }
+
   /**
    * fd_write: 將 iovec 陣列的資料寫入 fd（stdout=1 或 stderr=2）
    * iovec 結構：{ buf: i32, buf_len: i32 }（各 4 bytes，little-endian）
@@ -181,7 +214,7 @@ export function createWasiShim(stdinData: string, hostFunctions?: WasiHostFuncti
         path_link: () => WASI_ENOSYS,
       },
       // u6u host functions：讓 .wasm 零件透過 host function 呼叫外部服務
-      // .wasm 零件用 //go:wasmimport u6u http_request 宣告
+      // .wasm 零件用 //go:wasmimport u6u <name> 宣告
       u6u: {
         http_request: hostFunctions?.http_request
           ? async (urlPtr: number, urlLen: number, methodPtr: number, methodLen: number,
@@ -196,17 +229,64 @@ export function createWasiShim(stdinData: string, hostFunctions?: WasiHostFuncti
               const body = dec.decode(new Uint8Array(buf, bodyPtr, bodyLen));
               try {
                 const result = await hostFunctions!.http_request!(url, method, headers, body);
-                const encoded = new TextEncoder().encode(result);
+                return writeOut(buf, outPtr, outLenPtr, new TextEncoder().encode(result));
-                // 寫入結果到 outPtr 指向的 buffer
-                const view = new DataView(buf);
-                new Uint8Array(buf, outPtr, encoded.length).set(encoded);
-                view.setUint32(outLenPtr, encoded.length, true);
-                return 0; // success
               } catch {
-                return 1; // error
+                return 1;
               }
             }
-          : () => 1, // host function 未注入時回傳錯誤
+          : () => 1,
+
+        // kv_get(keyPtr, keyLen, outPtr, outLenPtr) → 0 成功；1 錯誤；2 找不到 key
+        kv_get: hostFunctions?.kv_get
+          ? async (keyPtr: number, keyLen: number, outPtr: number, outLenPtr: number): Promise<number> => {
+              if (!memory) return 1;
+              const buf = memory.buffer;
+              const key = new TextDecoder().decode(new Uint8Array(buf, keyPtr, keyLen));
+              try {
+                const result = await hostFunctions!.kv_get!(key);
+                if (result === null) return 2;
+                return writeOut(buf, outPtr, outLenPtr, new TextEncoder().encode(result));
+              } catch {
+                return 1;
+              }
+            }
+          : () => 1,
+
+        // crypto_decrypt(encPtr, encLen, ivPtr, ivLen, outPtr, outLenPtr) → 0 成功
+        // 輸入皆為 base64 字串（WASM 從 KV 讀到什麼就送什麼）
+        crypto_decrypt: hostFunctions?.crypto_decrypt
+          ? async (encPtr: number, encLen: number, ivPtr: number, ivLen: number,
+              outPtr: number, outLenPtr: number): Promise<number> => {
+              if (!memory) return 1;
+              const buf = memory.buffer;
+              const dec = new TextDecoder();
+              const encB64 = dec.decode(new Uint8Array(buf, encPtr, encLen));
+              const ivB64 = dec.decode(new Uint8Array(buf, ivPtr, ivLen));
+              try {
+                const plaintext = await hostFunctions!.crypto_decrypt!(encB64, ivB64);
+                return writeOut(buf, outPtr, outLenPtr, new TextEncoder().encode(plaintext));
+              } catch {
+                return 1;
+              }
+            }
+          : () => 1,
+
+        // crypto_sign_rs256(dataPtr, dataLen, pkcs8Ptr, pkcs8Len, outPtr, outLenPtr) → 0 成功
+        crypto_sign_rs256: hostFunctions?.crypto_sign_rs256
+          ? async (dataPtr: number, dataLen: number, pkcs8Ptr: number, pkcs8Len: number,
+              outPtr: number, outLenPtr: number): Promise<number> => {
+              if (!memory) return 1;
+              const buf = memory.buffer;
+              const data = new Uint8Array(new Uint8Array(buf, dataPtr, dataLen));
+              const pkcs8 = new Uint8Array(new Uint8Array(buf, pkcs8Ptr, pkcs8Len));
+              try {
+                const sig = await hostFunctions!.crypto_sign_rs256!(data, pkcs8);
+                return writeOut(buf, outPtr, outLenPtr, sig);
+              } catch {
+                return 1;
+              }
+            }
+          : () => 1,
       },
     },
 
@@ -241,3 +321,94 @@ export function createWasiShim(stdinData: string, hostFunctions?: WasiHostFuncti
 
   return shim;
 }
+
+// ── Worker 端 host function 實作（Phase 0.6）──────────────────────────────────
+//
+// 唯一合法位置：AES-GCM 解密與 RS256 簽章只准出現在本檔（02-forbidden.md §2.2）。
+// 由 component-loader 的 WASM runner 路徑呼叫，注入進 createWasiShim。
+//
+// 安全邊界：
+//   1. `ENCRYPTION_KEY` 只在 `crypto_decrypt` 內部讀 env，絕不經 stdin/回傳值傳給 WASM
+//   2. `kv_get` 依 key 前綴路由，且 `{api_key}:cred:*` 必須符合 stdin 傳入的 api_key（越權檢查）
+//   3. 未知前綴回傳 null（WASM 收到 kv_get 回傳 2 = 找不到）
+
+function hexToUint8Array(hex: string): Uint8Array {
+  const bytes = new Uint8Array(hex.length / 2);
+  for (let i = 0; i < hex.length; i += 2) bytes[i / 2] = parseInt(hex.slice(i, i + 2), 16);
+  return bytes;
+}
+
+function base64ToUint8Array(b64: string): Uint8Array {
+  const binary = atob(b64);
+  const bytes = new Uint8Array(binary.length);
+  for (let i = 0; i < binary.length; i++) bytes[i] = binary.charCodeAt(i);
+  return bytes;
+}
+
+/**
+ * 依 key 前綴路由到對應 KV binding，並做越權檢查。
+ * - `auth_recipe:{service}` → env.RECIPES
+ * - `{apiKey}:cred:{name}`   → env.CREDENTIALS_KV（前綴必須等於 caller 的 apiKey）
+ * - 其他前綴 → null（拒絕）
+ */
+async function routedKvGet(env: ArcrunHostEnv, apiKey: string, key: string): Promise<string | null> {
+  if (key.startsWith('auth_recipe:')) {
+    return env.RECIPES.get(key);
+  }
+  const credMatch = key.match(/^([^:]+):cred:.+$/);
+  if (credMatch) {
+    if (credMatch[1] !== apiKey) {
+      // 越權：WASM 嘗試讀其他租戶的 credential
+      return null;
+    }
+    return env.CREDENTIALS_KV.get(key);
+  }
+  return null;
+}
+
+/**
+ * AES-GCM 解密。encryption key 由 env.ENCRYPTION_KEY 在本 function 內讀取，
+ * 永不傳給 WASM。輸入為 base64 字串，輸出為 UTF-8 plaintext。
+ */
+async function aesGcmDecrypt(env: ArcrunHostEnv, encryptedB64: string, ivB64: string): Promise<string> {
+  const keyBytes = hexToUint8Array(env.ENCRYPTION_KEY);
+  const cryptoKey = await crypto.subtle.importKey(
+    'raw', keyBytes, { name: 'AES-GCM' }, false, ['decrypt'],
+  );
+  const plaintext = await crypto.subtle.decrypt(
+    { name: 'AES-GCM', iv: base64ToUint8Array(ivB64) },
+    cryptoKey,
+    base64ToUint8Array(encryptedB64),
+  );
+  return new TextDecoder().decode(plaintext);
+}
+
+/**
+ * RSASSA-PKCS1-v1_5 + SHA-256 簽章。private key 以 PKCS8 bytes 傳入（由 WASM 零件解析 PEM 後送進來）。
+ */
+async function rsaPkcs1Sha256Sign(data: Uint8Array, pkcs8: Uint8Array): Promise<Uint8Array> {
+  const cryptoKey = await crypto.subtle.importKey(
+    'pkcs8',
+    pkcs8,
+    { name: 'RSASSA-PKCS1-v1_5', hash: 'SHA-256' },
+    false,
+    ['sign'],
+  );
+  const sig = await crypto.subtle.sign('RSASSA-PKCS1-v1_5', cryptoKey, data);
+  return new Uint8Array(sig);
+}
+
+/**
+ * 建立 arcrun host function 組合（kv_get / crypto_decrypt / crypto_sign_rs256）。
+ * 由 WASM runner（component-loader 的 WASM 路徑）呼叫，與 api_key 綁定以做越權檢查。
+ *
+ * http_request 不由本 factory 提供 — auth primitive WASM 與 API WASM 零件若需要
+ * 發 HTTP，由呼叫者（component-loader）另外注入，以便個別限制可達主機。
+ */
+export function createArcrunHostFunctions(env: ArcrunHostEnv, apiKey: string): WasiHostFunctions {
+  return {
+    kv_get: (key: string) => routedKvGet(env, apiKey, key),
+    crypto_decrypt: (encB64: string, ivB64: string) => aesGcmDecrypt(env, encB64, ivB64),
+    crypto_sign_rs256: (data: Uint8Array, pkcs8: Uint8Array) => rsaPkcs1Sha256Sign(data, pkcs8),
+  };
+}

registry/components/auth_static_key/component.contract.yaml

@@ -0,0 +1,67 @@
+canonical_id: "auth_static_key"
+display_name: "Auth Primitive — Static Key"
+category: "auth"
+version: "v1"
+wasi_target: "preview1"
+stability: "floating"
+runtime_compat:
+  - "cf-workers"
+  - "workerd"
+  - "wazero"
+constraints:
+  max_size_kb: 2048
+  max_cold_start_ms: 50
+  no_network_syscall: true
+  no_filesystem_syscall: true
+  io_model: "stdin_stdout_json"
+input_schema:
+  type: object
+  required: [action, api_key, service]
+  properties:
+    action:
+      type: string
+      enum: [authenticate]
+      description: 目前僅支援 authenticate;static_key 無 refresh 概念
+    api_key:
+      type: string
+      description: 租戶識別(ak_ 前綴),用來組 {api_key}:cred:{name} KV key
+    service:
+      type: string
+      description: auth recipe 名稱,對應 auth_recipe:{service} 的 KV 記錄
+    request:
+      type: object
+      description: (保留)下游零件的 HTTP request 上下文;static_key 當前不使用
+output_schema:
+  type: object
+  properties:
+    success:
+      type: boolean
+    auth_headers:
+      type: object
+      additionalProperties:
+        type: string
+    auth_query:
+      type: object
+      additionalProperties:
+        type: string
+    auth_body:
+      type: object
+      additionalProperties:
+        type: string
+    runtime:
+      type: object
+      description: Static key 不使用;欄位保留以對齊其他 auth primitive
+gherkin_tests:
+  - scenario: "缺少 api_key"
+    given: '{"action":"authenticate","service":"openai"}'
+    then_contains: '{"success":false'
+  - scenario: "找不到 auth recipe"
+    given: '{"action":"authenticate","api_key":"ak_nonexistent","service":"nonexistent"}'
+    then_contains: '{"success":false'
+tags: [auth, credential, primitive, static_key]
+description: "Static key auth primitive。讀取 auth_recipe + 解密 required_secrets + 展開 {{secret.X}} 模板,回傳 auth_headers / auth_query / auth_body。涵蓋 Bearer token / API key / Basic auth / 自訂 header 等 80% 服務。透過 host function kv_get + crypto_decrypt,plaintext 永不離開 WASM。"
+config_example: |
+  auth_step:
+    component: "auth_static_key"
+    action: "authenticate"
+    service: "openai"      # 對應 auth_recipe:openai 的 KV 記錄

registry/components/auth_static_key/go.mod

@@ -0,0 +1,3 @@
+module component
+
+go 1.21

registry/components/auth_static_key/main.go

@@ -0,0 +1,276 @@
+// auth_static_key — static key auth primitive
+//
+// 讀取 auth_recipe:{service} + 解密 required_secrets + 展開 {{secret.X}} 模板,
+// 回傳 auth_headers / auth_query / auth_body。
+//
+// 所有外部 I/O 都透過 host function:
+//   - u6u.kv_get          — 依 key 前綴路由到 RECIPES / CREDENTIALS_KV (host 做越權檢查)
+//   - u6u.crypto_decrypt  — AES-GCM 解密 (encryption key 由 host 持有,不暴露給 WASM)
+//
+//go:build tinygo
+
+package main
+
+import (
+	"encoding/json"
+	"io"
+	"os"
+	"strings"
+	"unsafe"
+)
+
+// ── host function 宣告 ───────────────────────────────────────────────────────
+
+// kv_get(keyPtr, keyLen, outPtr, outLenPtr) → 0 成功 / 1 錯誤 / 2 找不到
+//
+//go:wasmimport u6u kv_get
+func hostKvGet(
+	keyPtr uintptr, keyLen uint32,
+	outPtr uintptr, outLenPtr uintptr,
+) uint32
+
+// crypto_decrypt(encPtr, encLen, ivPtr, ivLen, outPtr, outLenPtr) → 0 成功
+// enc/iv 為 base64 字串(即 KV 中儲存的格式)
+//
+//go:wasmimport u6u crypto_decrypt
+func hostCryptoDecrypt(
+	encPtr uintptr, encLen uint32,
+	ivPtr uintptr, ivLen uint32,
+	outPtr uintptr, outLenPtr uintptr,
+) uint32
+
+// ── 型別 ─────────────────────────────────────────────────────────────────────
+
+type Input struct {
+	Action  string          `json:"action"`
+	APIKey  string          `json:"api_key"`
+	Service string          `json:"service"`
+	Request json.RawMessage `json:"request,omitempty"`
+}
+
+type SecretRequirement struct {
+	Key      string `json:"key"`
+	Label    string `json:"label"`
+	Optional bool   `json:"optional,omitempty"`
+}
+
+type AuthInjectSpec struct {
+	Header map[string]string `json:"header,omitempty"`
+	Query  map[string]string `json:"query,omitempty"`
+	Body   map[string]string `json:"body,omitempty"`
+}
+
+type AuthRecipe struct {
+	Kind            string              `json:"kind"`
+	Service         string              `json:"service"`
+	Primitive       string              `json:"primitive"`
+	RequiredSecrets []SecretRequirement `json:"required_secrets"`
+	Inject          AuthInjectSpec      `json:"inject"`
+}
+
+type EncryptedRecord struct {
+	Encrypted string `json:"encrypted"`
+	IV        string `json:"iv"`
+}
+
+// ── main ─────────────────────────────────────────────────────────────────────
+
+func main() {
+	raw, err := io.ReadAll(os.Stdin)
+	if err != nil {
+		writeError("failed to read stdin: " + err.Error())
+		return
+	}
+
+	var input Input
+	if err := json.Unmarshal(raw, &input); err != nil {
+		writeError("invalid input JSON: " + err.Error())
+		return
+	}
+
+	if input.APIKey == "" {
+		writeError("api_key 必填")
+		return
+	}
+	if input.Service == "" {
+		writeError("service 必填")
+		return
+	}
+	if input.Action != "" && input.Action != "authenticate" {
+		writeError("auth_static_key 僅支援 action=authenticate")
+		return
+	}
+
+	// 1. 讀 auth recipe
+	recipeJSON, status := kvGet("auth_recipe:" + input.Service)
+	if status == 2 {
+		writeError("找不到 auth recipe: " + input.Service)
+		return
+	}
+	if status != 0 {
+		writeError("kv_get 失敗(auth_recipe)")
+		return
+	}
+
+	var recipe AuthRecipe
+	if err := json.Unmarshal([]byte(recipeJSON), &recipe); err != nil {
+		writeError("auth recipe JSON 解析失敗: " + err.Error())
+		return
+	}
+	if recipe.Primitive != "static_key" {
+		writeError("auth recipe " + input.Service + " 的 primitive 不是 static_key (是 " + recipe.Primitive + ")")
+		return
+	}
+
+	// 2. 解密所有 non-optional required_secrets
+	secrets := make(map[string]string)
+	for _, req := range recipe.RequiredSecrets {
+		if req.Optional {
+			continue
+		}
+		kvKey := input.APIKey + ":cred:" + req.Key
+		encJSON, s := kvGet(kvKey)
+		if s == 2 {
+			writeError("缺少 credential: " + req.Key + " (" + req.Label + ")。修復: 編輯 credentials.yaml 後執行 acr creds push")
+			return
+		}
+		if s != 0 {
+			writeError("kv_get 失敗(credential " + req.Key + ")")
+			return
+		}
+
+		var rec EncryptedRecord
+		if err := json.Unmarshal([]byte(encJSON), &rec); err != nil {
+			writeError("credential " + req.Key + " 格式錯誤: " + err.Error())
+			return
+		}
+
+		plaintext, ok := cryptoDecrypt(rec.Encrypted, rec.IV)
+		if !ok {
+			writeError("credential " + req.Key + " 解密失敗")
+			return
+		}
+		secrets[req.Key] = plaintext
+	}
+
+	// 3. 展開模板 (static_key 沒有 runtime,傳空 map)
+	runtime := map[string]string{}
+	authHeaders := interpolateRecord(recipe.Inject.Header, secrets, runtime)
+	authQuery := interpolateRecord(recipe.Inject.Query, secrets, runtime)
+	authBody := interpolateRecord(recipe.Inject.Body, secrets, runtime)
+
+	// 4. 輸出
+	out, _ := json.Marshal(map[string]interface{}{
+		"success":      true,
+		"auth_headers": authHeaders,
+		"auth_query":   authQuery,
+		"auth_body":    authBody,
+		"runtime":      runtime,
+	})
+	os.Stdout.Write(out)
+}
+
+// ── helpers ──────────────────────────────────────────────────────────────────
+
+func writeError(msg string) {
+	out, _ := json.Marshal(map[string]interface{}{
+		"success":      false,
+		"error":        msg,
+		"auth_headers": map[string]string{},
+		"auth_query":   map[string]string{},
+		"auth_body":    map[string]string{},
+	})
+	os.Stdout.Write(out)
+}
+
+// kvGet 呼叫 host function,回傳 (value, status)。status: 0=成功 1=錯誤 2=找不到
+func kvGet(key string) (string, uint32) {
+	keyBytes := []byte(key)
+	outBuf := make([]byte, 65536)
+	var outLen uint32
+
+	status := hostKvGet(
+		uintptr(unsafe.Pointer(&keyBytes[0])), uint32(len(keyBytes)),
+		uintptr(unsafe.Pointer(&outBuf[0])), uintptr(unsafe.Pointer(&outLen)),
+	)
+	if status != 0 {
+		return "", status
+	}
+	return string(outBuf[:outLen]), 0
+}
+
+// cryptoDecrypt 呼叫 host function 做 AES-GCM 解密
+// enc/iv 均為 base64 字串;回傳 UTF-8 plaintext
+func cryptoDecrypt(encB64, ivB64 string) (string, bool) {
+	encBytes := []byte(encB64)
+	ivBytes := []byte(ivB64)
+	outBuf := make([]byte, 65536)
+	var outLen uint32
+
+	// 處理空字串的防呆(TinyGo 取 &[]byte{}[0] 會 panic)
+	if len(encBytes) == 0 || len(ivBytes) == 0 {
+		return "", false
+	}
+
+	status := hostCryptoDecrypt(
+		uintptr(unsafe.Pointer(&encBytes[0])), uint32(len(encBytes)),
+		uintptr(unsafe.Pointer(&ivBytes[0])), uint32(len(ivBytes)),
+		uintptr(unsafe.Pointer(&outBuf[0])), uintptr(unsafe.Pointer(&outLen)),
+	)
+	if status != 0 {
+		return "", false
+	}
+	return string(outBuf[:outLen]), true
+}
+
+// interpolateTemplate 展開 {{secret.X}} 與 {{runtime.X}}。未知 key 展開為空字串(與 TS 版 parity)。
+// 其他 namespace 的 {{...}} 原樣保留(static_key 不解析)。
+func interpolateTemplate(template string, secrets, runtime map[string]string) string {
+	var b strings.Builder
+	b.Grow(len(template))
+	i := 0
+	for i < len(template) {
+		start := strings.Index(template[i:], "{{")
+		if start < 0 {
+			b.WriteString(template[i:])
+			break
+		}
+		b.WriteString(template[i : i+start])
+		openIdx := i + start
+		closeRel := strings.Index(template[openIdx+2:], "}}")
+		if closeRel < 0 {
+			b.WriteString(template[openIdx:])
+			break
+		}
+		inner := template[openIdx+2 : openIdx+2+closeRel]
+		advance := openIdx + 2 + closeRel + 2
+
+		switch {
+		case strings.HasPrefix(inner, "secret."):
+			key := inner[len("secret."):]
+			b.WriteString(secrets[key])
+		case strings.HasPrefix(inner, "runtime."):
+			key := inner[len("runtime."):]
+			b.WriteString(runtime[key])
+		default:
+			// 非本 primitive 負責的 namespace,原樣寫回
+			b.WriteString(template[openIdx:advance])
+		}
+		i = advance
+	}
+	return b.String()
+}
+
+func interpolateRecord(
+	record map[string]string,
+	secrets, runtime map[string]string,
+) map[string]string {
+	if record == nil {
+		return map[string]string{}
+	}
+	result := make(map[string]string, len(record))
+	for k, v := range record {
+		result[k] = interpolateTemplate(v, secrets, runtime)
+	}
+	return result
+}