diff --git a/.github/actions/npm-ci-retry/action.yml b/.github/actions/npm-ci-retry/action.yml
index 29e2960218..e0ef8d3e12 100644
--- a/.github/actions/npm-ci-retry/action.yml
+++ b/.github/actions/npm-ci-retry/action.yml
@@ -12,6 +12,26 @@ inputs:
 runs:
   using: composite
   steps:
+    - name: Select the lockfile-compatible npm version
+      id: npm
+      shell: bash
+      run: |
+        set -euo pipefail
+        expected=$(node -p "require('./config/ci/toolchain.json').npm")
+        if ! [[ "$expected" =~ ^[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
+          echo "Invalid pinned npm version" >&2
+          exit 1
+        fi
+        if [ "$(npm --version)" != "$expected" ]; then
+          npm install --global "npm@$expected" --no-audit --no-fund
+        fi
+        actual=$(npm --version)
+        if [ "$actual" != "$expected" ]; then
+          echo "npm version differs from the lockfile toolchain" >&2
+          exit 1
+        fi
+        echo "version=$actual" >> "$GITHUB_OUTPUT"
+
     - name: Resolve Node version for the cache key
       id: node
       shell: bash
@@ -35,7 +55,7 @@ runs:
       uses: actions/cache@55cc8345863c7cc4c66a329aec7e433d2d1c52a9 # v6.1.0
       with:
         path: node_modules
-        key: node-modules-${{ runner.os }}-${{ runner.arch }}-${{ steps.node.outputs.version }}-${{ hashFiles('package-lock.json', '.npmrc', 'scripts/build/postinstall.mjs', 'scripts/build/postinstallSupport.mjs', 'scripts/build/colocateOptionals.mjs', 'scripts/build/wreqJsNative.mjs', 'scripts/build/fixPlaywrightAndroid.mjs', 'scripts/build/native-binary-compat.mjs') }}
+        key: node-modules-v2-${{ runner.os }}-${{ runner.arch }}-${{ steps.node.outputs.version }}-${{ steps.npm.outputs.version }}-${{ hashFiles('package-lock.json', '.npmrc', 'scripts/build/postinstall.mjs', 'scripts/build/postinstallSupport.mjs', 'scripts/build/colocateOptionals.mjs', 'scripts/build/wreqJsNative.mjs', 'scripts/build/fixPlaywrightAndroid.mjs', 'scripts/build/native-binary-compat.mjs') }}
 
     - name: npm ci (with retry)
       if: steps.node-modules.outputs.cache-hit != 'true'
diff --git a/.github/workflows/release-acceptance.yml b/.github/workflows/release-acceptance.yml
index 75527ad2dd..89f0f5b65b 100644
--- a/.github/workflows/release-acceptance.yml
+++ b/.github/workflows/release-acceptance.yml
@@ -23,9 +23,11 @@ jobs:
           persist-credentials: false
       - uses: actions/setup-node@v5
         with:
-          node-version: "22"
+          node-version-file: ".node-version"
           cache: npm
-      - run: npm ci
+      - uses: ./.github/actions/npm-ci-retry
+        with:
+          cache: "false"
       - name: Emit shadow acceptance report
         run: |
           node scripts/quality/validate-release-acceptance.mjs \
diff --git a/config/ci/toolchain.json b/config/ci/toolchain.json
new file mode 100644
index 0000000000..f58d87cd25
--- /dev/null
+++ b/config/ci/toolchain.json
@@ -0,0 +1,3 @@
+{
+  "npm": "11.15.0"
+}
diff --git a/tests/unit/build/ci-toolchain-parity.test.ts b/tests/unit/build/ci-toolchain-parity.test.ts
new file mode 100644
index 0000000000..76596e4b62
--- /dev/null
+++ b/tests/unit/build/ci-toolchain-parity.test.ts
@@ -0,0 +1,97 @@
+import assert from "node:assert/strict";
+import { spawnSync } from "node:child_process";
+import { readFileSync, mkdtempSync, mkdirSync, writeFileSync, rmSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import test from "node:test";
+import { parse } from "yaml";
+
+const root = new URL("../../../", import.meta.url);
+const action = parse(
+  readFileSync(new URL(".github/actions/npm-ci-retry/action.yml", root), "utf8")
+);
+const acceptance = parse(
+  readFileSync(new URL(".github/workflows/release-acceptance.yml", root), "utf8")
+);
+
+test("release acceptance uses the repository's supported development runtime and installer", () => {
+  const steps = acceptance.jobs.acceptance.steps;
+  const setup = steps.find((step: { uses?: string }) =>
+    step.uses?.startsWith("actions/setup-node@")
+  );
+  assert.equal(setup.with["node-version-file"], ".node-version");
+  assert.ok(
+    steps.some((step: { uses?: string }) => step.uses === "./.github/actions/npm-ci-retry")
+  );
+});
+
+test("the exact npm version participates in dependency cache identity", () => {
+  const cache = action.runs.steps.find((step: { id?: string }) => step.id === "node-modules");
+  assert.match(cache.with.key, /steps\.npm\.outputs\.version/);
+  assert.match(cache.with.key, /node-modules-v2-/);
+  const bootstrap = action.runs.steps.findIndex((step: { id?: string }) => step.id === "npm");
+  const restore = action.runs.steps.findIndex(
+    (step: { id?: string }) => step.id === "node-modules"
+  );
+  assert.ok(
+    bootstrap >= 0 && bootstrap < restore,
+    "resolve the installer before restoring its tree"
+  );
+});
+
+for (const fixture of [
+  { initial: "11.15.0", installed: "11.15.0", installExit: 0, exit: 0, installs: 0 },
+  { initial: "10.9.8", installed: "11.15.0", installExit: 0, exit: 0, installs: 1 },
+  { initial: "10.9.8", installed: "11.15.0", installExit: 42, exit: 42, installs: 1 },
+  { initial: "10.9.8", installed: "10.9.8", installExit: 0, exit: 1, installs: 1 },
+]) {
+  test(`npm bootstrap ${JSON.stringify(fixture)}`, () => {
+    const dir = mkdtempSync(join(tmpdir(), "omni-npm-toolchain-"));
+    try {
+      mkdirSync(join(dir, "config/ci"), { recursive: true });
+      writeFileSync(
+        join(dir, "config/ci/toolchain.json"),
+        readFileSync(new URL("config/ci/toolchain.json", root))
+      );
+      writeFileSync(join(dir, "version"), fixture.initial);
+      writeFileSync(join(dir, "calls"), "");
+      const run = action.runs.steps.find((step: { id?: string }) => step.id === "npm").run;
+      const result = spawnSync(
+        "bash",
+        [
+          "-euo",
+          "pipefail",
+          "-c",
+          `
+        npm() {
+          if [ "$1" = "--version" ]; then cat version; return; fi
+          printf '%s\\n' "$*" >> calls
+          if [ "$FIXTURE_INSTALL_EXIT" != "0" ]; then return "$FIXTURE_INSTALL_EXIT"; fi
+          printf '%s' "$FIXTURE_INSTALLED_VERSION" > version
+        }
+        ${run}
+      `,
+        ],
+        {
+          cwd: dir,
+          encoding: "utf8",
+          env: {
+            ...process.env,
+            FIXTURE_INSTALL_EXIT: String(fixture.installExit),
+            FIXTURE_INSTALLED_VERSION: fixture.installed,
+            GITHUB_OUTPUT: join(dir, "outputs"),
+          },
+        }
+      );
+      assert.equal(result.status, fixture.exit, result.stderr);
+      const calls = readFileSync(join(dir, "calls"), "utf8").trim();
+      assert.equal(calls ? calls.split("\n").length : 0, fixture.installs);
+      if (fixture.installs)
+        assert.match(calls, /^install --global npm@11\.15\.0 --no-audit --no-fund$/);
+      if (fixture.exit === 0)
+        assert.equal(readFileSync(join(dir, "outputs"), "utf8"), "version=11.15.0\n");
+    } finally {
+      rmSync(dir, { recursive: true, force: true });
+    }
+  });
+}