diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6648f457..eab73739 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -70,7 +70,8 @@ jobs:
         if: steps.ws.outputs.exists == 'true'
         run: make test
 
-      - uses: taiki-e/install-action@5d880190e41a7608c29a5c91c6b5d24561d53850 # cargo-deny
+      - name: Install cargo-deny (retry + crates.io 回退)
+        run: ./scripts/install-cargo-deny.sh
         if: steps.ws.outputs.exists == 'true'
 
       - name: make deny（零诊断门禁）
@@ -143,7 +144,8 @@ jobs:
           targets: aarch64-apple-darwin, x86_64-apple-darwin
       - uses: Swatinem/rust-cache@6323deb102c322ba6fcbdcafc7e3dddab59af2b6 # v2
         if: steps.changes.outputs.lane == 'full'
-      - uses: taiki-e/install-action@5d880190e41a7608c29a5c91c6b5d24561d53850 # cargo-deny
+      - name: Install cargo-deny (retry + crates.io 回退)
+        run: ./scripts/install-cargo-deny.sh
         if: steps.changes.outputs.lane != 'docs'
       - name: Verify Rust and privacy
         if: steps.changes.outputs.lane == 'full'
diff --git a/.github/workflows/isolated-imk-notary.yml b/.github/workflows/isolated-imk-notary.yml
index 8caa391d..08f6f4ac 100644
--- a/.github/workflows/isolated-imk-notary.yml
+++ b/.github/workflows/isolated-imk-notary.yml
@@ -44,9 +44,8 @@ jobs:
           components: rustfmt, clippy
           targets: aarch64-apple-darwin, x86_64-apple-darwin
       - uses: Swatinem/rust-cache@6323deb102c322ba6fcbdcafc7e3dddab59af2b6
-      - uses: taiki-e/install-action@5d880190e41a7608c29a5c91c6b5d24561d53850
-        with:
-          tool: cargo-deny
+      - name: Install cargo-deny (retry + crates.io 回退)
+        run: ./scripts/install-cargo-deny.sh
       - name: Verify and build owned test host
         env:
           TARGET_TEST_ROOT: ${{ inputs.target_root }}
diff --git a/.github/workflows/isolated-update-drill.yml b/.github/workflows/isolated-update-drill.yml
index c0512d68..d8930169 100644
--- a/.github/workflows/isolated-update-drill.yml
+++ b/.github/workflows/isolated-update-drill.yml
@@ -52,9 +52,8 @@ jobs:
           components: rustfmt, clippy
           targets: aarch64-apple-darwin, x86_64-apple-darwin
       - uses: Swatinem/rust-cache@6323deb102c322ba6fcbdcafc7e3dddab59af2b6
-      - uses: taiki-e/install-action@5d880190e41a7608c29a5c91c6b5d24561d53850
-        with:
-          tool: cargo-deny
+      - name: Install cargo-deny (retry + crates.io 回退)
+        run: ./scripts/install-cargo-deny.sh
       - name: Verify and build owned drill host
         env:
           TARGET_TEST_ROOT: ${{ inputs.target_root }}
diff --git a/.github/workflows/macos-acceptance.yml b/.github/workflows/macos-acceptance.yml
index 8477095d..d1e92948 100644
--- a/.github/workflows/macos-acceptance.yml
+++ b/.github/workflows/macos-acceptance.yml
@@ -40,7 +40,8 @@ jobs:
           components: rustfmt, clippy
           targets: aarch64-apple-darwin, x86_64-apple-darwin
       - uses: Swatinem/rust-cache@6323deb102c322ba6fcbdcafc7e3dddab59af2b6 # v2
-      - uses: taiki-e/install-action@5d880190e41a7608c29a5c91c6b5d24561d53850 # cargo-deny
+      - name: Install cargo-deny (retry + crates.io 回退)
+        run: ./scripts/install-cargo-deny.sh
       - name: Verify and build
         run: |
           make verify
diff --git a/.github/workflows/macos-nightly.yml b/.github/workflows/macos-nightly.yml
index bc4c7c4f..93cd7f41 100644
--- a/.github/workflows/macos-nightly.yml
+++ b/.github/workflows/macos-nightly.yml
@@ -33,7 +33,8 @@ jobs:
           components: rustfmt, clippy
           targets: aarch64-apple-darwin, x86_64-apple-darwin
       - uses: Swatinem/rust-cache@6323deb102c322ba6fcbdcafc7e3dddab59af2b6 # v2
-      - uses: taiki-e/install-action@5d880190e41a7608c29a5c91c6b5d24561d53850 # cargo-deny
+      - name: Install cargo-deny (retry + crates.io 回退)
+        run: ./scripts/install-cargo-deny.sh
       - name: Repository gates
         run: make verify
       - name: Offline macOS and packaging regressions
diff --git a/.github/workflows/security.yml b/.github/workflows/security.yml
index ee43553e..02563bfe 100644
--- a/.github/workflows/security.yml
+++ b/.github/workflows/security.yml
@@ -24,6 +24,7 @@ jobs:
       - uses: dtolnay/rust-toolchain@e2a55d2ffb04f378e9626c28d38b36d230d1e12f # master
         with:
           toolchain: ${{ steps.rust.outputs.channel }}
-      - uses: taiki-e/install-action@5d880190e41a7608c29a5c91c6b5d24561d53850 # cargo-deny
+      - name: Install cargo-deny (retry + crates.io 回退)
+        run: ./scripts/install-cargo-deny.sh
       - name: Dependency advisories
         run: cargo deny check advisories
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index da7752fc..0e69d997 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -92,6 +92,15 @@ Signed-off-by: Your Name <you@example.com>
 - uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
 ```
 
+**工具安装**（`cargo-deny` 等）统一走仓库脚本，不直接用 `install-action`：该 action 从 GitHub Release
+资产下载，2026-11-09 连续两次 504 让 `main` 的 macOS 任务假红。`scripts/install-cargo-deny.sh`
+自己下载并重试，失败退回 crates.io 源码编译，两条路都固定同一版本（`CARGO_DENY_VERSION`）：
+
+```yaml
+- name: Install cargo-deny (retry + crates.io 回退)
+  run: ./scripts/install-cargo-deny.sh
+```
+
 **升级步骤**（单独一个 `ci: bump ...` 提交，说明里附来源）：
 
 1. 在**官方仓库**查该 tag/branch 当前指向的 commit：
diff --git a/Makefile b/Makefile
index 534fad8b..12dbeac6 100644
--- a/Makefile
+++ b/Makefile
@@ -93,7 +93,7 @@ deny: check-workspace ## 依赖许可 / 漏洞 / 重复依赖检查（零诊断
 	$(CLEAN) $(CARGO) deny check
 
 bootstrap: ## 安装开发依赖（版本固定，见 MVP 审计 SEC-07）
-	cargo install cargo-deny --version 0.20.2 --locked
+	./scripts/install-cargo-deny.sh
 	cargo install cargo-fuzz --version 0.13.2 --locked
 
 EVAL_SAMPLES ?= tools/eval/samples.tsv
diff --git a/docs/reviews/263-1.2.1-audit-cleanup.md b/docs/reviews/263-1.2.1-audit-cleanup.md
index 97013c09..62322651 100644
--- a/docs/reviews/263-1.2.1-audit-cleanup.md
+++ b/docs/reviews/263-1.2.1-audit-cleanup.md
@@ -45,3 +45,17 @@
 - 每一步删除后跑 `make verify` 与离线回归；最终 `make macos-offline-tests`：**62 文件 / 328 例 PASS**（4 并发）。
 - `platforms/macos/dev-preview.sh --build-only` 通过（AppKit 面编译验证）。
 - 版本推进到 **1.2.1 / build 40**，发布稿 `docs/releases/1.2.1.md`；tag 需用户授权。
+
+## 5. CI 依赖安装去第三方（2026-11-09 追加）
+
+`main` 上两次连续的红灯都不是代码问题：`taiki-e/install-action` 从 GitHub Release 资产取
+`cargo-deny-0.20.2-aarch64-apple-darwin.tar.gz` 时拿到 **504**（重试 10 次约 60s 后失败），
+而同一提交在 `dev` 上早已全绿、重置后仍失败。
+
+处置：新增 `scripts/install-cargo-deny.sh`——固定版本、自下载 + 5 轮退避重试，失败退回
+`cargo install cargo-deny --version 0.20.2 --locked`；`ci.yml`（macos/check）、`security.yml`、
+`macos-acceptance.yml`、`macos-nightly.yml`、两个 isolated drill 工作流全部改用它；`make bootstrap`
+同一入口。好处是版本单一来源、少一个第三方 Action、下载路径可控。
+`CONTRIBUTING.md` §9 写明原因与用法，避免下次又改回 `install-action`。
+
+验证：脚本两条路径都实跑过（资产下载路径在干净 `HOME` 下安装成功并输出 `cargo-deny 0.20.2`）。
diff --git a/scripts/install-cargo-deny.sh b/scripts/install-cargo-deny.sh
new file mode 100755
index 00000000..ac6a9d11
--- /dev/null
+++ b/scripts/install-cargo-deny.sh
@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+# Install cargo-deny at the pinned version.
+#
+# CI 里 `taiki-e/install-action` 会从 GitHub Release 资产下载预编译包，该路径偶发 504
+# （2026-11-09 连续两次让 main 的 macOS 任务红掉，代码其实全绿）。这里自己下载并重试，
+# 失败时退回 crates.io 源码编译；两条路都固定同一版本，避免"工具版本漂移"变成假结论。
+set -euo pipefail
+
+VERSION="${CARGO_DENY_VERSION:-0.20.2}"
+export PATH="${HOME}/.cargo/bin:${PATH}"
+
+if command -v cargo-deny >/dev/null 2>&1 && cargo-deny --version 2>/dev/null | grep -q " ${VERSION}$"; then
+  echo "cargo-deny ${VERSION} 已就绪"
+  exit 0
+fi
+
+case "$(uname -s)-$(uname -m)" in
+  Darwin-arm64) TARGET="aarch64-apple-darwin" ;;
+  Darwin-x86_64) TARGET="x86_64-apple-darwin" ;;
+  Linux-x86_64) TARGET="x86_64-unknown-linux-musl" ;;
+  Linux-aarch64) TARGET="aarch64-unknown-linux-musl" ;;
+  *) TARGET="" ;;
+esac
+
+asset_install() {
+  [ -n "${TARGET}" ] || return 1
+  local url="https://github.com/EmbarkStudios/cargo-deny/releases/download/${VERSION}/cargo-deny-${VERSION}-${TARGET}.tar.gz"
+  local tmp
+  tmp="$(mktemp -d)"
+  for attempt in 1 2 3 4 5; do
+    if curl -fsSL --retry 3 --retry-all-errors --connect-timeout 20 --max-time 300 \
+      -o "${tmp}/cargo-deny.tar.gz" "${url}"; then
+      tar -xzf "${tmp}/cargo-deny.tar.gz" -C "${tmp}" --strip-components=1 \
+        "cargo-deny-${VERSION}-${TARGET}/cargo-deny" 2>/dev/null ||
+        tar -xzf "${tmp}/cargo-deny.tar.gz" -C "${tmp}" --strip-components=1
+      mkdir -p "${HOME}/.cargo/bin"
+      install -m 0755 "${tmp}/cargo-deny" "${HOME}/.cargo/bin/cargo-deny"
+      rm -rf "${tmp}"
+      return 0
+    fi
+    echo "下载 ${TARGET} 资产失败（第 ${attempt} 次），重试…" >&2
+    sleep $((attempt * 10))
+  done
+  rm -rf "${tmp}"
+  return 1
+}
+
+if asset_install && cargo-deny --version | grep -q " ${VERSION}$"; then
+  echo "cargo-deny ${VERSION} 已从 Release 资产安装"
+  exit 0
+fi
+
+echo "Release 资产不可用，改用 crates.io 源码编译（较慢但可靠）" >&2
+cargo install cargo-deny --version "${VERSION}" --locked --force
+cargo-deny --version