diff --git a/docs/QINGLONG_3_0_ARCHITECTURE_RFC.md b/docs/QINGLONG_3_0_ARCHITECTURE_RFC.md
index d4088d15..2b6c7e06 100644
--- a/docs/QINGLONG_3_0_ARCHITECTURE_RFC.md
+++ b/docs/QINGLONG_3_0_ARCHITECTURE_RFC.md
@@ -11,6 +11,7 @@
 
 最新增量证据（2026-08-15）：
 
+- D-318/ADR-0410（已接受）：Cluster Copilot diagnosis Model output 获得独立的只读 projected key authority。canonical `qinglong/copilot-failure-diagnosis-output-projected-keyring@v1` manifest 只允许一个 active key 与最多 16 个 historical 32-byte key；每次 `active()`/`resolve()` 都重新执行 Cluster 私有投影文件的 direct-root、根内 atomic symlink、single-link、mode、dev/inode/size/mtime 与双 realpath fence，不使用 cache、watcher、timer 或 Kubernetes API。该 authority 以结构兼容的本地窄端口位于既有 `cluster-control/copilot/failure-diagnosis/`，只通过 `failure-diagnosis-output-keyring` subpath 发布，避免 Cluster Control 默认源码反向依赖 AI；它不复用 Prompt output、Tool invocation/result 或 Provider credential key domain，也不提前声称 Copilot 产品入口已可达。定向回归 13/13、Cluster Control 239 pass/2 条件 skip、backend 1,207 pass/2 条件 skip、18-package clean build/test、四项架构审计与 14 档 Local artifact 全部通过；workspace 仍无单文件/浅平 package，Cluster Control 58 个源码中 56 个位于嵌套领域目录。默认 Edge/Standalone 保持 2,589,890/2,589,968 bytes，Edge/Standalone AI 保持 3,061,009/3,061,099 bytes，证明 Cluster-only subpath 被裁掉。本 Gate 不改 migration/schema/role/SQL/连接/HA 拓扑，因此数据库基线继续引用 ADR-0409 的 PostgreSQL 18.6 arm64 HA 130/130、timeline `1→2`；下一 Gate 是默认关闭的完整 Cluster Copilot composition，随后补齐 Tool failure、日志 missing/retired、Model admission 前 deadline/cancel 与 outcome-unknown 的 durable terminalization/recovery。
 - D-316/ADR-0408（已接受）：Cluster Copilot 现在能够从 ADR-0407 的 durable admission 恢复 exact `qinglong.run.log.excerpt@1.0.0` authority，复用通用 Trusted Tool start barrier、加密 success/failure completion、result catalog/rekey 和内建日志 adapter；确定性 start/completion identity 让 response-loss replay 直接打开既有证据，不重复读取日志或执行 adapter。Cluster invocation Artifact 使用独立 projected keyring，提供 active+historical material，但每次读取均重新执行 canonical path/symlink/mode/inode/realpath fence，且不取得 PostgreSQL Tool result generation authority。只有 exact `succeeded` completion 才能通过 `pg-9019` 的 SERIALIZABLE 事务把 Model Step 从 `pending` 原子推进到 `ready`，同时写 RunEvent、StepRunMutation 和 append-only unlock receipt；`failed|timed_out` 不解锁。本 Gate 不执行模型、不终态化 diagnosis Run，下一 Gate 是 ADR-0405 builder + Model Gateway + Copilot encrypted model completion/terminalization。实现仍为 18 个 package，无单文件/浅平 package；AI 175 个源码中 174 个、Cluster Control 56 个中 54 个位于嵌套目录，不新增依赖、进程、连接、timer/watcher/cache 或默认 Edge 成本。18-package clean build/test 全绿，AI 229 pass/3 条件 skip、backend 1,207 pass/2 条件 skip，四项架构审计零 finding；14 档 Local artifact 全通过，默认 Edge/Standalone 为 2,589,890/2,589,968 bytes。PostgreSQL 18.4 arm64 HA 130/130、timeline `1→2`，首次执行只读两次日志、密文不含敏感 fixture，提升后 exact replay 零日志读取；报告 SHA-256 为 `d525a303696e178d777b021b376729bd2c5382fb5eb7bc98466a2b79d3940517`，独立审计与 Docker 清理通过。
 - D-317/ADR-0409（已接受）：已解锁的 Cluster failure-diagnosis Model Step 现在从 durable encrypted Tool completion 重开受信日志投影，经 ADR-0405 builder 和既有 Model Gateway 执行；只有显式安装的 Copilot success sink 可以接管成功返回。Copilot `GenerateResult` 使用独立 AES-256-GCM Artifact，绑定 plan、Tool completion、egress evidence 与 Model identity，公开 reference、ModelInvocation completion、RunEvent 和审计均不含明文。通用 `DurableModelInvocationCoordinator` 已改为领域无关的 `ModelInvocationAtomicSuccess<TReference>`，消除对 Plugin Prompt Artifact 的反向依赖；Plugin Prompt 通过 adapter 保持兼容。`pg-9020` 在一个 SERIALIZABLE 事务中原子提交 ciphertext、Model completion、StepRun/Event 与 usage/pricing/quota settlement，再由可重放 finalization 事务把 diagnosis Run 推进为 `succeeded|failed|timed_out`；两事务间崩溃只补 finalization，existing start/completion/finalization replay 均不重复调用 Provider。当前仍不自动终态化 Tool failure、日志 missing/retired、Model admission 前 deadline/cancel，也不把 `outcome_unknown` 冒充失败；Cluster 专用 output projected keyring 与产品 composition 完成前该入口保持不可达。实现仍在既有 18 个 package 的嵌套领域目录内，不新增进程、队列、timer/watcher/cache 或默认 Edge 成本。最终 AI 233 pass/3 条件 skip、18-package clean build/test 与 backend 1,207 pass/2 条件 skip/0 fail，四项架构审计零 finding；workspace 无单文件或浅平 package，AI 183 个源码中 182 个位于嵌套目录。14 档 Local Profile artifact 全部通过，默认 Edge/Standalone 为 2,589,890/2,589,968 bytes，Edge/Standalone AI 为 3,061,009/3,061,099 bytes。PostgreSQL 18.6 arm64 HA 130/130、timeline `1→2`，报告 SHA-256 为 `8401634f30635b45bfb583b02e94ac41f023bf8a0bdbcfd9744ebf459ab0d8f8`，独立证据审计与 Docker 零残留。
 - D-315/ADR-0407（已接受）：Cluster Copilot 故障诊断不修改或重新打开终态源 Run，而是用源 Run/version、最新已结束 Attempt/status 与日志 Artifact 建立 exact fence，原子创建独立 `copilot_failure_diagnosis` Run、admission event、`ready` 的 `qinglong.run.log.excerpt@1.0.0` Tool Step、以其为父节点的 `pending` Model Step 和不可变 receipt。计划只接受 `cluster-control` 的 reviewed snapshot/binding/Policy/subject authority；`approval_required`、Tool contract/输入漂移或未显式允许的模型出口均在写库前失败关闭。`ql3_ai` 新增有界 admission ledger 与仅授予 runtime 的 `SECURITY DEFINER` source snapshot，在 SERIALIZABLE 事务内重验 active Project/binding 和源 Run/Attempt；response-loss replay 对 JSONB 做结构 exact 比较而不依赖无语义的对象键序。Copilot/Plugin 这类 StepRun 聚合从通用 Task orphan recovery 排除，后续由各自状态机恢复，不能伪造顶层 Attempt 或被错误终态化。本阶段只 admission，不执行 Tool/模型、不授予行动权；Tool encrypted completion、Model 解锁和 Copilot encrypted model completion 是下一 Gate。最终 18-package clean build/test 与 backend 1,207 pass/2 条件 skip/0 fail，四项边界审计零 finding且 workspace 仍为 18 package、无单文件/浅平 package；14 档 Local Profile artifact 全通过，默认 Edge/Standalone 不引入 Cluster admission。PostgreSQL 18.4 arm64 HA 128/128、timeline `1→2`，报告 SHA-256 为 `a4ed1edec783e3f5b42507c0f8e11b94c59dbe44a57e691017d1445ec9d115e2`，证据审计与 Docker 清理通过。
diff --git a/docs/adr/ADR-0410-cluster-copilot-failure-diagnosis-output-key-authority.md b/docs/adr/ADR-0410-cluster-copilot-failure-diagnosis-output-key-authority.md
new file mode 100644
index 00000000..9cdeb834
--- /dev/null
+++ b/docs/adr/ADR-0410-cluster-copilot-failure-diagnosis-output-key-authority.md
@@ -0,0 +1,76 @@
+# ADR-0410：Cluster Copilot Failure Diagnosis Output Key Authority
+
+- 状态：Accepted
+- 日期：2026-08-15
+- 关联 RFC：QL-RFC-0001 D-318、Phase 2
+- 关联 ADR：ADR-0405、ADR-0406、ADR-0408、ADR-0409
+
+## 问题
+
+ADR-0409 已定义 Copilot diagnosis Model output 的独立 AES-256-GCM Artifact 与 key provider 端口，
+但 Cluster 产品还没有可以注入该端口的部署密钥 authority。若复用 Plugin Prompt output、Tool
+invocation 或 Tool result keyring，会让一次轮换或退役跨越不同数据域，并使最小权限部署无法证明
+哪个进程能够加解密诊断结果。
+
+同时，路由设备不应因为 Cluster Copilot 能力增加任何 keyring、watcher 或常驻内存；Cluster 节点
+也不能把 Kubernetes Secret/CSI projection 的瞬时路径、可写文件或跨目录 symlink 当成可信密钥。
+
+## 决策
+
+1. 新增独立 schema `qinglong/copilot-failure-diagnosis-output-projected-keyring@v1`。manifest 只包含
+   一个 `activeKeyId` 和最多 16 个 canonical 32-byte key；key ID 有界，JSON 必须 exact 且 canonical。
+2. `ClusterCopilotFailureDiagnosisOutputProjectedKeyring` 实现 ADR-0409 的 `active()` 与
+   `resolve(keyId)` 端口。每次操作重新打开 projection，不持有 cache、watcher、timer、Kubernetes
+   API client 或轮换权限；返回的 key material 由调用者使用后清零。
+3. 文件读取复用 Cluster Control package-private `PrivateProjectedFileReader`：配置根必须是 direct
+   absolute directory；允许 Kubernetes atomic-writer 的根内 symlink，但最终 regular file 必须单链接、
+   只读、不可执行、other-inaccessible，并在读取前后复验 dev/inode/size/mtime 与双 realpath fence。
+4. Copilot output key ID/material 不得与 Plugin Prompt output、Tool invocation、Tool result 或 Provider
+   credential 互换。不同 schema 即使 key bytes 相同也拒绝；部署文档必须要求独立 Secret 和 mount root。
+5. 能力内聚在现有 `@qinglong/cluster-control` 的 `copilot/failure-diagnosis/` 目录，只通过显式
+   `failure-diagnosis-output-keyring` subpath 发布；不新增 workspace package、依赖、进程、Pod、连接、
+   route 或默认 Profile import。
+6. 本 Gate 只建立 runtime key custody，不提前伪造产品可用性。完整 Copilot composition 仍需同时装配
+   admission、Tool invocation/result keyring、Artifact/log reader、Model Gateway、PostgreSQL repository
+   与恢复状态机；该入口在后续 Gate 完成前保持不可达。
+
+## 被否决方案
+
+1. **复用 Plugin Prompt output keyring**：两个产品域的 retention、授权和泄漏半径不同。
+2. **复用 Tool invocation/result keyring**：混淆请求、Tool 结果与模型结论的加密用途。
+3. **从环境变量读取 base64 key**：密钥进入进程环境与诊断面，且无法安全保留历史 key。
+4. **启动时读取一次并永久缓存**：轮换无法生效，退役和文件漂移也无法失败关闭。
+5. **为 keyring 新建 package**：没有独立部署进程或依赖边界，只会增加薄包。
+
+## 验证标准
+
+1. 覆盖 canonical manifest、active rotation、historical resolve、missing key、wrong schema、缺失 active、
+   非 32-byte material、可写 projection 与根外 symlink。
+2. Cluster Control 完整构建/测试、package/dependency/Edge import/Cluster deployment 审计全部通过。
+3. workspace 保持 18 个 package、无单文件或浅平 package；14 档 Local Profile artifact 证明默认
+   Edge/Standalone 与本地 AI/MCP 不携带该 Cluster-only subpath。
+
+## 后续门禁
+
+1. 在独立默认关闭的 Cluster Copilot composition 中同时装配 admission、Tool、Model 与本 keyring，
+   不能把 Plugin Prompt gateway 的 completion sink 当作 Copilot sink。
+2. 建立 Tool failure、日志 missing/retired、Model admission 前 deadline/cancel 与 outcome-unknown
+   resolution 的 durable terminalization/recovery。
+3. 再开放经 authentication、Policy、audit 和 exact source fence 的 Cluster API/CLI/UI/MCP 入口。
+
+## 当前验证
+
+1. 定向 keyring 与 package-boundary 回归 13/13；Cluster Control 完整测试 241 项中 239 pass、2 条
+   环境条件 skip、0 fail。
+2. 18 个 QL3 package 从清理 `dist` 开始顺序构建并执行全部 package tests，退出码为 0；backend
+   全量 1,209 项中 1,207 pass、2 条环境条件 skip、0 fail。
+3. package boundary、dependency firewall、Edge import 与 Cluster deployment 四项架构审计均为
+   `compatible: true`、零 finding。workspace 仍为 18 个 package，`singleSourcePackages` 与
+   `shallowSourcePackages` 均为空；Cluster Control 的 58 个源码中，56 个位于嵌套领域目录，根层仅
+   保留 2 个 binary entry。
+4. 14 档 Local Profile artifact 全部通过。默认 Edge/Standalone 仍为
+   2,589,890/2,589,968 bytes，Edge/Standalone AI 仍为 3,061,009/3,061,099 bytes；新增
+   Cluster-only subpath 未进入默认、本地 AI 或 MCP 产品闭包。
+5. 本 Gate 不修改 migration、schema、PostgreSQL role、SQL、连接或 HA 拓扑，因此不重复制造一份与
+   变更无关的数据库实证；ADR-0409 的 PostgreSQL 18.6 arm64 HA 130/130、timeline `1→2` 仍是当前
+   数据库基线。
diff --git a/docs/adr/README.md b/docs/adr/README.md
index 77e9cefa..33f0b337 100644
--- a/docs/adr/README.md
+++ b/docs/adr/README.md
@@ -413,6 +413,7 @@
 | [ADR-0407](./ADR-0407-cluster-copilot-failure-diagnosis-run-admission.md)                          | Cluster Copilot Failure Diagnosis Run Admission                                                                                                       | Accepted |
 | [ADR-0408](./ADR-0408-cluster-copilot-failure-diagnosis-tool-execution.md)                         | Cluster Copilot Failure Diagnosis Tool Execution 与原子 Model 解锁                                                                                    | Accepted |
 | [ADR-0409](./ADR-0409-cluster-copilot-failure-diagnosis-model-execution.md)                        | Cluster Copilot Failure Diagnosis Model Execution、密文输出与 Run 终态化                                                                               | Accepted |
+| [ADR-0410](./ADR-0410-cluster-copilot-failure-diagnosis-output-key-authority.md)                   | Cluster Copilot Failure Diagnosis Output Projected Key Authority                                                                                        | Accepted |
 
 ## 规则
 
diff --git a/packages/ql3-cluster-control/package.json b/packages/ql3-cluster-control/package.json
index 53f29168..690b9375 100644
--- a/packages/ql3-cluster-control/package.json
+++ b/packages/ql3-cluster-control/package.json
@@ -35,6 +35,11 @@
       "require": "./dist/application-runtime/aiProductionApplication.js",
       "default": "./dist/application-runtime/aiProductionApplication.js"
     },
+    "./failure-diagnosis-output-keyring": {
+      "types": "./dist/copilot/failure-diagnosis/outputProjectedKeyring.d.ts",
+      "require": "./dist/copilot/failure-diagnosis/outputProjectedKeyring.js",
+      "default": "./dist/copilot/failure-diagnosis/outputProjectedKeyring.js"
+    },
     "./http": {
       "types": "./dist/transport/httpSurface.d.ts",
       "require": "./dist/transport/httpSurface.js",
diff --git a/packages/ql3-cluster-control/src/copilot/failure-diagnosis/outputKeyringManifest.ts b/packages/ql3-cluster-control/src/copilot/failure-diagnosis/outputKeyringManifest.ts
new file mode 100644
index 00000000..fddc26cf
--- /dev/null
+++ b/packages/ql3-cluster-control/src/copilot/failure-diagnosis/outputKeyringManifest.ts
@@ -0,0 +1,196 @@
+import { Buffer } from 'node:buffer';
+import { createHash } from 'node:crypto';
+
+export const CLUSTER_COPILOT_FAILURE_DIAGNOSIS_OUTPUT_KEYRING_MANIFEST_SCHEMA =
+  'qinglong/copilot-failure-diagnosis-output-projected-keyring@v1' as const;
+export const MAX_CLUSTER_COPILOT_FAILURE_DIAGNOSIS_OUTPUT_KEYRING_BYTES =
+  64 * 1024;
+export const MAX_CLUSTER_COPILOT_FAILURE_DIAGNOSIS_OUTPUT_PROJECTED_KEYS = 16;
+
+const KEY_ID_PATTERN = /^[A-Za-z0-9][A-Za-z0-9._-]{0,127}$/;
+const BASE64URL_PATTERN = /^[A-Za-z0-9_-]+$/;
+const PROJECTION_DIGEST_DOMAIN = Buffer.from(
+  'qinglong/copilot-failure-diagnosis-output-projected-keyring-digest@v1\0',
+  'utf8',
+);
+
+export interface ClusterCopilotFailureDiagnosisOutputKeyringManifest {
+  readonly schema: typeof CLUSTER_COPILOT_FAILURE_DIAGNOSIS_OUTPUT_KEYRING_MANIFEST_SCHEMA;
+  readonly activeKeyId: string;
+  readonly keys: Readonly<Record<string, string>>;
+}
+
+export interface ClusterCopilotFailureDiagnosisOutputKeyringSummary {
+  readonly schemaVersion: 1;
+  readonly activeKeyId: string;
+  readonly keyIds: readonly string[];
+  readonly projectionDigest: string;
+}
+
+export interface ClusterCopilotFailureDiagnosisOutputKeyMaterial {
+  readonly keyId: string;
+  readonly key: Uint8Array;
+}
+
+export class InvalidClusterCopilotFailureDiagnosisOutputKeyringManifestError extends TypeError {
+  readonly code =
+    'QL3_CLUSTER_COPILOT_FAILURE_DIAGNOSIS_OUTPUT_KEYRING_MANIFEST_INVALID';
+
+  constructor() {
+    super('Cluster Copilot failure diagnosis output keyring manifest is invalid');
+    this.name =
+      'InvalidClusterCopilotFailureDiagnosisOutputKeyringManifestError';
+  }
+}
+
+function invalid(): never {
+  throw new InvalidClusterCopilotFailureDiagnosisOutputKeyringManifestError();
+}
+
+function dataRecord(value: unknown): Record<string, unknown> {
+  if (
+    !value ||
+    typeof value !== 'object' ||
+    Array.isArray(value) ||
+    Object.getPrototypeOf(value) !== Object.prototype
+  ) {
+    return invalid();
+  }
+  return value as Record<string, unknown>;
+}
+
+function exactKeys(value: object, expected: readonly string[]): boolean {
+  const actual = Object.keys(value).sort();
+  const canonical = [...expected].sort();
+  return (
+    actual.length === canonical.length &&
+    actual.every((key, index) => key === canonical[index])
+  );
+}
+
+export function normalizeClusterCopilotFailureDiagnosisOutputKeyringManifest(
+  value: unknown,
+): Readonly<ClusterCopilotFailureDiagnosisOutputKeyringManifest> {
+  const manifest = dataRecord(value);
+  if (
+    !exactKeys(manifest, ['activeKeyId', 'keys', 'schema']) ||
+    manifest.schema !==
+      CLUSTER_COPILOT_FAILURE_DIAGNOSIS_OUTPUT_KEYRING_MANIFEST_SCHEMA ||
+    typeof manifest.activeKeyId !== 'string' ||
+    !KEY_ID_PATTERN.test(manifest.activeKeyId)
+  ) {
+    return invalid();
+  }
+  const keys = dataRecord(manifest.keys);
+  const entries = Object.entries(keys).sort(([left], [right]) =>
+    left < right ? -1 : left > right ? 1 : 0,
+  );
+  if (
+    entries.length < 1 ||
+    entries.length >
+      MAX_CLUSTER_COPILOT_FAILURE_DIAGNOSIS_OUTPUT_PROJECTED_KEYS
+  ) {
+    return invalid();
+  }
+  const normalized: (readonly [string, string])[] = [];
+  for (const [keyId, encoded] of entries) {
+    let material: Buffer | undefined;
+    try {
+      if (
+        !KEY_ID_PATTERN.test(keyId) ||
+        typeof encoded !== 'string' ||
+        !BASE64URL_PATTERN.test(encoded)
+      ) {
+        return invalid();
+      }
+      material = Buffer.from(encoded, 'base64url');
+      if (
+        material.byteLength !== 32 ||
+        material.toString('base64url') !== encoded
+      ) {
+        return invalid();
+      }
+      normalized.push(Object.freeze([keyId, encoded] as const));
+    } finally {
+      material?.fill(0);
+    }
+  }
+  const normalizedKeys = Object.freeze(Object.fromEntries(normalized));
+  if (normalizedKeys[manifest.activeKeyId] === undefined) return invalid();
+  return Object.freeze({
+    schema:
+      CLUSTER_COPILOT_FAILURE_DIAGNOSIS_OUTPUT_KEYRING_MANIFEST_SCHEMA,
+    activeKeyId: manifest.activeKeyId,
+    keys: normalizedKeys,
+  });
+}
+
+export function parseClusterCopilotFailureDiagnosisOutputKeyringManifest(
+  bytes: Buffer,
+): Readonly<ClusterCopilotFailureDiagnosisOutputKeyringManifest> {
+  try {
+    if (
+      !Buffer.isBuffer(bytes) ||
+      bytes.byteLength < 1 ||
+      bytes.byteLength >
+        MAX_CLUSTER_COPILOT_FAILURE_DIAGNOSIS_OUTPUT_KEYRING_BYTES
+    ) {
+      return invalid();
+    }
+    return normalizeClusterCopilotFailureDiagnosisOutputKeyringManifest(
+      JSON.parse(bytes.toString('utf8')),
+    );
+  } catch (error) {
+    if (
+      error instanceof
+      InvalidClusterCopilotFailureDiagnosisOutputKeyringManifestError
+    ) {
+      throw error;
+    }
+    return invalid();
+  }
+}
+
+export function canonicalClusterCopilotFailureDiagnosisOutputKeyringManifest(
+  value: ClusterCopilotFailureDiagnosisOutputKeyringManifest,
+): Buffer {
+  const manifest =
+    normalizeClusterCopilotFailureDiagnosisOutputKeyringManifest(value);
+  return Buffer.from(`${JSON.stringify(manifest)}\n`, 'utf8');
+}
+
+export function resolveClusterCopilotFailureDiagnosisOutputKeyringMaterial(
+  value: ClusterCopilotFailureDiagnosisOutputKeyringManifest,
+  keyId: string,
+): Readonly<ClusterCopilotFailureDiagnosisOutputKeyMaterial> | null {
+  if (typeof keyId !== 'string' || !KEY_ID_PATTERN.test(keyId)) {
+    return invalid();
+  }
+  const manifest =
+    normalizeClusterCopilotFailureDiagnosisOutputKeyringManifest(value);
+  const encoded = manifest.keys[keyId];
+  if (encoded === undefined) return null;
+  const key = Buffer.from(encoded, 'base64url');
+  if (key.byteLength !== 32 || key.toString('base64url') !== encoded) {
+    key.fill(0);
+    return invalid();
+  }
+  return Object.freeze({ keyId, key });
+}
+
+export function summarizeClusterCopilotFailureDiagnosisOutputKeyringManifest(
+  value: ClusterCopilotFailureDiagnosisOutputKeyringManifest,
+): Readonly<ClusterCopilotFailureDiagnosisOutputKeyringSummary> {
+  const manifest =
+    normalizeClusterCopilotFailureDiagnosisOutputKeyringManifest(value);
+  const keyIds = Object.freeze(Object.keys(manifest.keys).sort());
+  return Object.freeze({
+    schemaVersion: 1 as const,
+    activeKeyId: manifest.activeKeyId,
+    keyIds,
+    projectionDigest: createHash('sha256')
+      .update(PROJECTION_DIGEST_DOMAIN)
+      .update(JSON.stringify(manifest))
+      .digest('hex'),
+  });
+}
diff --git a/packages/ql3-cluster-control/src/copilot/failure-diagnosis/outputProjectedKeyring.ts b/packages/ql3-cluster-control/src/copilot/failure-diagnosis/outputProjectedKeyring.ts
new file mode 100644
index 00000000..7cf57793
--- /dev/null
+++ b/packages/ql3-cluster-control/src/copilot/failure-diagnosis/outputProjectedKeyring.ts
@@ -0,0 +1,176 @@
+import { Buffer } from 'node:buffer';
+
+import { PrivateProjectedFileReader } from '../../security/privateProjectedFile';
+import {
+  MAX_CLUSTER_COPILOT_FAILURE_DIAGNOSIS_OUTPUT_KEYRING_BYTES,
+  canonicalClusterCopilotFailureDiagnosisOutputKeyringManifest,
+  parseClusterCopilotFailureDiagnosisOutputKeyringManifest,
+  resolveClusterCopilotFailureDiagnosisOutputKeyringMaterial,
+  summarizeClusterCopilotFailureDiagnosisOutputKeyringManifest,
+  type ClusterCopilotFailureDiagnosisOutputKeyMaterial,
+  type ClusterCopilotFailureDiagnosisOutputKeyringManifest,
+  type ClusterCopilotFailureDiagnosisOutputKeyringSummary,
+} from './outputKeyringManifest';
+
+const DATA_FILE_NAME = /^[A-Za-z0-9][A-Za-z0-9._-]{0,252}$/;
+
+export {
+  CLUSTER_COPILOT_FAILURE_DIAGNOSIS_OUTPUT_KEYRING_MANIFEST_SCHEMA,
+  MAX_CLUSTER_COPILOT_FAILURE_DIAGNOSIS_OUTPUT_KEYRING_BYTES,
+  MAX_CLUSTER_COPILOT_FAILURE_DIAGNOSIS_OUTPUT_PROJECTED_KEYS,
+  InvalidClusterCopilotFailureDiagnosisOutputKeyringManifestError,
+  canonicalClusterCopilotFailureDiagnosisOutputKeyringManifest,
+  normalizeClusterCopilotFailureDiagnosisOutputKeyringManifest,
+  parseClusterCopilotFailureDiagnosisOutputKeyringManifest,
+  resolveClusterCopilotFailureDiagnosisOutputKeyringMaterial,
+  summarizeClusterCopilotFailureDiagnosisOutputKeyringManifest,
+  type ClusterCopilotFailureDiagnosisOutputKeyringManifest,
+  type ClusterCopilotFailureDiagnosisOutputKeyringSummary,
+} from './outputKeyringManifest';
+
+export interface ClusterCopilotFailureDiagnosisOutputProjectedKeyringOptions {
+  readonly rootDirectory: string;
+  readonly dataFileName?: string;
+}
+
+export interface ClusterCopilotFailureDiagnosisOutputKeyProvider {
+  active(): Promise<ClusterCopilotFailureDiagnosisOutputKeyMaterial>;
+  resolve(
+    keyId: string,
+  ): Promise<ClusterCopilotFailureDiagnosisOutputKeyMaterial | null>;
+}
+
+export class ClusterCopilotFailureDiagnosisOutputProjectedKeyringUnavailableError extends Error {
+  readonly code =
+    'QL3_CLUSTER_COPILOT_FAILURE_DIAGNOSIS_OUTPUT_PROJECTED_KEYRING_UNAVAILABLE';
+
+  constructor(options?: ErrorOptions) {
+    super(
+      'Projected Cluster Copilot failure diagnosis output keyring is unavailable',
+      options,
+    );
+    this.name =
+      'ClusterCopilotFailureDiagnosisOutputProjectedKeyringUnavailableError';
+  }
+}
+
+function unavailable(
+  cause?: unknown,
+): ClusterCopilotFailureDiagnosisOutputProjectedKeyringUnavailableError {
+  return new ClusterCopilotFailureDiagnosisOutputProjectedKeyringUnavailableError(
+    { cause: cause instanceof Error ? cause : undefined },
+  );
+}
+
+function dataFileName(value: unknown): string {
+  if (typeof value !== 'string' || !DATA_FILE_NAME.test(value)) {
+    throw unavailable();
+  }
+  return value;
+}
+
+async function readManifest(
+  reader: PrivateProjectedFileReader,
+  fileName: string,
+): Promise<Readonly<ClusterCopilotFailureDiagnosisOutputKeyringManifest>> {
+  let bytes: Buffer | undefined;
+  let canonical: Buffer | undefined;
+  try {
+    bytes = await reader.read(fileName);
+    const manifest =
+      parseClusterCopilotFailureDiagnosisOutputKeyringManifest(bytes);
+    canonical =
+      canonicalClusterCopilotFailureDiagnosisOutputKeyringManifest(manifest);
+    if (!canonical.equals(bytes)) throw unavailable();
+    return manifest;
+  } catch (cause) {
+    throw cause instanceof
+      ClusterCopilotFailureDiagnosisOutputProjectedKeyringUnavailableError
+      ? cause
+      : unavailable(cause);
+  } finally {
+    bytes?.fill(0);
+    canonical?.fill(0);
+  }
+}
+
+/** Read-only, no-cache Copilot diagnosis output key authority. */
+export class ClusterCopilotFailureDiagnosisOutputProjectedKeyring
+  implements ClusterCopilotFailureDiagnosisOutputKeyProvider
+{
+  readonly #reader: PrivateProjectedFileReader;
+  readonly #dataFileName: string;
+
+  constructor(
+    options: ClusterCopilotFailureDiagnosisOutputProjectedKeyringOptions,
+  ) {
+    if (!options || typeof options !== 'object' || Array.isArray(options)) {
+      throw unavailable();
+    }
+    try {
+      this.#reader = new PrivateProjectedFileReader({
+        rootDirectory: options.rootDirectory,
+        minimumBytes: 1,
+        maximumBytes:
+          MAX_CLUSTER_COPILOT_FAILURE_DIAGNOSIS_OUTPUT_KEYRING_BYTES,
+        access: 'read_only_keyring',
+      });
+      this.#dataFileName = dataFileName(options.dataFileName ?? 'keyring.json');
+    } catch (cause) {
+      throw unavailable(cause);
+    }
+  }
+
+  async verify(): Promise<
+    Readonly<ClusterCopilotFailureDiagnosisOutputKeyringSummary>
+  > {
+    return summarizeClusterCopilotFailureDiagnosisOutputKeyringManifest(
+      await readManifest(this.#reader, this.#dataFileName),
+    );
+  }
+
+  async active(): Promise<ClusterCopilotFailureDiagnosisOutputKeyMaterial> {
+    try {
+      const manifest = await readManifest(this.#reader, this.#dataFileName);
+      const material =
+        resolveClusterCopilotFailureDiagnosisOutputKeyringMaterial(
+          manifest,
+          manifest.activeKeyId,
+        );
+      if (!material) throw unavailable();
+      return material;
+    } catch (cause) {
+      throw cause instanceof
+        ClusterCopilotFailureDiagnosisOutputProjectedKeyringUnavailableError
+        ? cause
+        : unavailable(cause);
+    }
+  }
+
+  async resolve(
+    keyId: string,
+  ): Promise<ClusterCopilotFailureDiagnosisOutputKeyMaterial | null> {
+    try {
+      return resolveClusterCopilotFailureDiagnosisOutputKeyringMaterial(
+        await readManifest(this.#reader, this.#dataFileName),
+        keyId,
+      );
+    } catch (cause) {
+      throw cause instanceof
+        ClusterCopilotFailureDiagnosisOutputProjectedKeyringUnavailableError
+        ? cause
+        : unavailable(cause);
+    }
+  }
+}
+
+export async function createClusterCopilotFailureDiagnosisOutputProjectedKeyring(
+  options: ClusterCopilotFailureDiagnosisOutputProjectedKeyringOptions,
+): Promise<
+  Readonly<ClusterCopilotFailureDiagnosisOutputProjectedKeyring>
+> {
+  const provider =
+    new ClusterCopilotFailureDiagnosisOutputProjectedKeyring(options);
+  await provider.verify();
+  return provider;
+}
diff --git a/packages/ql3-cluster-control/test/copilot-failure-diagnosis-output-projected-keyring.test.cjs b/packages/ql3-cluster-control/test/copilot-failure-diagnosis-output-projected-keyring.test.cjs
new file mode 100644
index 00000000..eaf64500
--- /dev/null
+++ b/packages/ql3-cluster-control/test/copilot-failure-diagnosis-output-projected-keyring.test.cjs
@@ -0,0 +1,178 @@
+const assert = require('node:assert/strict');
+const fs = require('node:fs/promises');
+const os = require('node:os');
+const path = require('node:path');
+const { afterEach, test } = require('node:test');
+
+const rootExport = require('@qinglong/cluster-control');
+const {
+  CLUSTER_COPILOT_FAILURE_DIAGNOSIS_OUTPUT_KEYRING_MANIFEST_SCHEMA,
+  ClusterCopilotFailureDiagnosisOutputProjectedKeyring,
+  ClusterCopilotFailureDiagnosisOutputProjectedKeyringUnavailableError,
+  InvalidClusterCopilotFailureDiagnosisOutputKeyringManifestError,
+  canonicalClusterCopilotFailureDiagnosisOutputKeyringManifest,
+  createClusterCopilotFailureDiagnosisOutputProjectedKeyring,
+  normalizeClusterCopilotFailureDiagnosisOutputKeyringManifest,
+} = require('@qinglong/cluster-control/failure-diagnosis-output-keyring');
+
+const roots = [];
+
+afterEach(async () => {
+  await Promise.all(
+    roots
+      .splice(0)
+      .map((root) => fs.rm(root, { recursive: true, force: true })),
+  );
+});
+
+async function tempRoot(label = 'ql3-copilot-output-keyring-') {
+  const root = await fs.mkdtemp(path.join(os.tmpdir(), label));
+  roots.push(root);
+  return root;
+}
+
+function manifest(activeKeyId, keys) {
+  return Object.freeze({
+    schema:
+      CLUSTER_COPILOT_FAILURE_DIAGNOSIS_OUTPUT_KEYRING_MANIFEST_SCHEMA,
+    activeKeyId,
+    keys: Object.freeze(keys),
+  });
+}
+
+async function publish(root, generationName, value, mode = 0o440) {
+  const generation = path.join(root, generationName);
+  await fs.mkdir(generation, { mode: 0o750 });
+  const target = path.join(generation, 'keyring.json');
+  await fs.writeFile(
+    target,
+    canonicalClusterCopilotFailureDiagnosisOutputKeyringManifest(value),
+    { mode },
+  );
+  await fs.chmod(target, mode);
+  const next = path.join(root, '..data-next');
+  await fs.symlink(generationName, next);
+  await fs.rename(next, path.join(root, '..data'));
+  try {
+    await fs.symlink('..data/keyring.json', path.join(root, 'keyring.json'));
+  } catch (error) {
+    if (error.code !== 'EEXIST') throw error;
+  }
+}
+
+test('projected Copilot output keyring rotates active material without caching', async () => {
+  const root = await tempRoot();
+  const keyOne = Buffer.alloc(32, 0x31);
+  const keyTwo = Buffer.alloc(32, 0x32);
+  await publish(
+    root,
+    '..2026_08_15_01',
+    manifest('copilot-output-one', {
+      'copilot-output-one': keyOne.toString('base64url'),
+    }),
+  );
+  const provider =
+    await createClusterCopilotFailureDiagnosisOutputProjectedKeyring({
+      rootDirectory: root,
+    });
+  const first = await provider.active();
+  assert.equal(first.keyId, 'copilot-output-one');
+  assert.deepEqual(Buffer.from(first.key), keyOne);
+  first.key.fill(0);
+
+  await publish(
+    root,
+    '..2026_08_15_02',
+    manifest('copilot-output-two', {
+      'copilot-output-one': keyOne.toString('base64url'),
+      'copilot-output-two': keyTwo.toString('base64url'),
+    }),
+  );
+  const second = await provider.active();
+  assert.equal(second.keyId, 'copilot-output-two');
+  assert.deepEqual(Buffer.from(second.key), keyTwo);
+  second.key.fill(0);
+  const historical = await provider.resolve('copilot-output-one');
+  assert.ok(historical);
+  assert.deepEqual(Buffer.from(historical.key), keyOne);
+  historical.key.fill(0);
+  assert.equal(await provider.resolve('missing-key'), null);
+
+  const summary = await provider.verify();
+  assert.deepEqual(summary.keyIds, [
+    'copilot-output-one',
+    'copilot-output-two',
+  ]);
+  assert.equal(summary.activeKeyId, 'copilot-output-two');
+  assert.match(summary.projectionDigest, /^[0-9a-f]{64}$/);
+});
+
+test('manifest rejects missing active, wrong domains and non-canonical material', () => {
+  const key = Buffer.alloc(32, 0x41).toString('base64url');
+  assert.throws(
+    () =>
+      normalizeClusterCopilotFailureDiagnosisOutputKeyringManifest({
+        ...manifest('missing-key', { 'copilot-output-one': key }),
+      }),
+    InvalidClusterCopilotFailureDiagnosisOutputKeyringManifestError,
+  );
+  assert.throws(
+    () =>
+      normalizeClusterCopilotFailureDiagnosisOutputKeyringManifest({
+        ...manifest('copilot-output-one', { 'copilot-output-one': key }),
+        schema: 'qinglong/cluster-tool-invocation-projected-keyring@v1',
+      }),
+    InvalidClusterCopilotFailureDiagnosisOutputKeyringManifestError,
+  );
+  assert.throws(
+    () =>
+      normalizeClusterCopilotFailureDiagnosisOutputKeyringManifest(
+        manifest('copilot-output-one', {
+          'copilot-output-one': Buffer.alloc(31, 0x41).toString('base64url'),
+        }),
+      ),
+    InvalidClusterCopilotFailureDiagnosisOutputKeyringManifestError,
+  );
+  assert.equal(
+    rootExport.ClusterCopilotFailureDiagnosisOutputProjectedKeyring,
+    undefined,
+  );
+});
+
+test('projected Copilot output keyring rejects writable and escaping files', async () => {
+  const writableRoot = await tempRoot();
+  const key = Buffer.alloc(32, 0x51).toString('base64url');
+  await publish(
+    writableRoot,
+    '..2026_08_15_01',
+    manifest('copilot-output-one', { 'copilot-output-one': key }),
+    0o640,
+  );
+  await assert.rejects(
+    () =>
+      new ClusterCopilotFailureDiagnosisOutputProjectedKeyring({
+        rootDirectory: writableRoot,
+      }).verify(),
+    ClusterCopilotFailureDiagnosisOutputProjectedKeyringUnavailableError,
+  );
+
+  const escapeRoot = await tempRoot();
+  const outsideRoot = await tempRoot('ql3-copilot-output-outside-');
+  const outsideFile = path.join(outsideRoot, 'keyring.json');
+  await fs.writeFile(
+    outsideFile,
+    canonicalClusterCopilotFailureDiagnosisOutputKeyringManifest(
+      manifest('copilot-output-one', { 'copilot-output-one': key }),
+    ),
+    { mode: 0o440 },
+  );
+  await fs.chmod(outsideFile, 0o440);
+  await fs.symlink(outsideFile, path.join(escapeRoot, 'keyring.json'));
+  await assert.rejects(
+    () =>
+      new ClusterCopilotFailureDiagnosisOutputProjectedKeyring({
+        rootDirectory: escapeRoot,
+      }).verify(),
+    ClusterCopilotFailureDiagnosisOutputProjectedKeyringUnavailableError,
+  );
+});
diff --git a/test/back/ql3PackageBoundaryAudit.test.cjs b/test/back/ql3PackageBoundaryAudit.test.cjs
index e416597e..e2a82dc2 100644
--- a/test/back/ql3PackageBoundaryAudit.test.cjs
+++ b/test/back/ql3PackageBoundaryAudit.test.cjs
@@ -385,10 +385,10 @@ test('current QL3 workspace has exactly eighteen reviewed package boundaries', (
       rootSourceFileRoles: clusterControl.rootSourceFileRoles,
     },
     {
-      sourceFiles: 56,
+      sourceFiles: 58,
       rootSourceFiles: 2,
       rootSourceLines: 195,
-      nestedSourceFiles: 54,
+      nestedSourceFiles: 56,
       rootSourceFileRoles: {
         'aiCli.ts': 'binary_entry',
         'cli.ts': 'binary_entry',