diff --git a/scripts/AGENTS.md b/scripts/AGENTS.md
index 1b7e256e5131..f7b1bd269ef7 100644
--- a/scripts/AGENTS.md
+++ b/scripts/AGENTS.md
@@ -18,6 +18,11 @@ This directory owns local tooling, script wrappers, and generated-artifact helpe
 - Metadata-only or explicitly narrow commands may skip the lock when the existing helper logic says that is safe.
 - If you change the lock heuristics, add or update the narrow tests under `test/scripts/`.
 
+## PR Prepare Gates
+
+- `scripts/pr prepare-gates` holds the heavy-check lock for its whole local gate block (`scripts/pr-gates-lock.mjs`), so concurrent gate runs across `.worktrees` queue as units instead of dying on child lock timeouts or vitest no-output watchdog kills.
+- `OPENCLAW_PR_GATES_REMOTE=testbox` runs the full-suite `pnpm test` gate on a Blacksmith Testbox through `scripts/crabbox-wrapper.mjs` (same delegation as `check:changed`); `pnpm build`/`pnpm check` stay local. The `tbx_` lease id and Actions run URL land in `.local/gates.env` (`REMOTE_GATES_*`) and `.local/prep.md`. Use it for reviewed trusted code when a loaded host makes the local 88-shard run stall-kill; contributor/fork code stays on secretless CI or sanitized AWS unless a maintainer explicitly approves credentialed execution.
+
 ## Generated Outputs
 
 - If a script writes generated artifacts, keep the source-of-truth generator, the package script, and the matching verification/check command aligned.
diff --git a/scripts/pr-gates-lock.mjs b/scripts/pr-gates-lock.mjs
new file mode 100644
index 000000000000..aa589a91ecc1
--- /dev/null
+++ b/scripts/pr-gates-lock.mjs
@@ -0,0 +1,75 @@
+// Holds the shared local heavy-check lock for a whole scripts/pr gate block so
+// concurrent gate runs across .worktrees serialize before their first command
+// instead of dying mid-test on child lock timeouts or no-output watchdog kills.
+import fs from "node:fs";
+import {
+  acquireLocalHeavyCheckLockSync,
+  resolveLocalHeavyCheckEnv,
+} from "./lib/local-heavy-check-runtime.mjs";
+
+// A queued gate block legitimately waits out another full gate run; the
+// 10-minute per-command default in the lock runtime is far too short for that.
+const DEFAULT_GATE_LOCK_TIMEOUT_MS = 2 * 60 * 60 * 1000;
+const PARENT_WATCH_INTERVAL_MS = 2_000;
+
+function parseArgs(argv) {
+  const args = { statusFile: "" };
+  for (let index = 0; index < argv.length; index += 1) {
+    if (argv[index] === "--status-file") {
+      args.statusFile = argv[index + 1] ?? "";
+      index += 1;
+      continue;
+    }
+    throw new Error(`Unknown option: ${argv[index]}`);
+  }
+  if (!args.statusFile) {
+    throw new Error("Usage: node scripts/pr-gates-lock.mjs --status-file <path>");
+  }
+  return args;
+}
+
+function main() {
+  const { statusFile } = parseArgs(process.argv.slice(2));
+  const baseEnv = resolveLocalHeavyCheckEnv(process.env);
+  const env = baseEnv.OPENCLAW_HEAVY_CHECK_LOCK_TIMEOUT_MS
+    ? baseEnv
+    : { ...baseEnv, OPENCLAW_HEAVY_CHECK_LOCK_TIMEOUT_MS: String(DEFAULT_GATE_LOCK_TIMEOUT_MS) };
+
+  const parentPid = process.ppid;
+  const release = acquireLocalHeavyCheckLockSync({
+    cwd: process.cwd(),
+    env,
+    toolName: "pr-gates",
+  });
+  let released = false;
+  const releaseOnce = () => {
+    if (released) {
+      return;
+    }
+    released = true;
+    release();
+  };
+
+  process.on("exit", releaseOnce);
+  for (const signal of ["SIGINT", "SIGTERM", "SIGHUP"]) {
+    process.on(signal, () => {
+      releaseOnce();
+      process.exit(0);
+    });
+  }
+
+  fs.writeFileSync(statusFile, "acquired\n");
+
+  // The owner-pid reclaim in the lock runtime already covers a SIGKILLed
+  // holder; this watch releases promptly when the gate shell dies mid-block.
+  // ppid 1 also counts as dead: orphans reparent to init/launchd, and a
+  // helper that started orphaned has no gate block to hold the lock for.
+  setInterval(() => {
+    if (process.ppid !== parentPid || process.ppid === 1) {
+      releaseOnce();
+      process.exit(0);
+    }
+  }, PARENT_WATCH_INTERVAL_MS);
+}
+
+main();
diff --git a/scripts/pr-lib/gates.sh b/scripts/pr-lib/gates.sh
index 9a2c09c86cd5..42687078d653 100644
--- a/scripts/pr-lib/gates.sh
+++ b/scripts/pr-lib/gates.sh
@@ -31,6 +31,175 @@ pin_worktree_bundled_plugins_dir() {
   export OPENCLAW_BUNDLED_PLUGINS_DIR="${OPENCLAW_BUNDLED_PLUGINS_DIR:-$PWD/extensions}"
 }
 
+resolve_pr_gates_remote_mode() {
+  case "${OPENCLAW_PR_GATES_REMOTE:-}" in
+    "")
+      printf 'local\n'
+      ;;
+    testbox)
+      printf 'testbox\n'
+      ;;
+    *)
+      echo "Unsupported OPENCLAW_PR_GATES_REMOTE=${OPENCLAW_PR_GATES_REMOTE} (supported: testbox)." >&2
+      return 1
+      ;;
+  esac
+}
+
+PR_GATES_LOCK_PID=""
+PR_GATES_LOCK_STATUS_FILE=""
+
+acquire_pr_gates_lock() {
+  # Serialize whole gate blocks across .worktrees on the shared heavy-check
+  # lock; a queued gate run waits here, before its first command, instead of
+  # dying on child lock timeouts or shard no-output watchdog kills mid-test.
+  if [ "${OPENCLAW_TEST_HEAVY_CHECK_LOCK_HELD:-}" = "1" ]; then
+    return 0
+  fi
+
+  PR_GATES_LOCK_STATUS_FILE=$(mktemp)
+  # Use the canonical helper: the PR branch under test may predate it.
+  local scripts_dir="${script_parent_dir:-}"
+  if [ -z "$scripts_dir" ]; then
+    scripts_dir=$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)
+  fi
+  node "$scripts_dir/pr-gates-lock.mjs" --status-file "$PR_GATES_LOCK_STATUS_FILE" &
+  PR_GATES_LOCK_PID=$!
+  while [ ! -s "$PR_GATES_LOCK_STATUS_FILE" ]; do
+    if ! kill -0 "$PR_GATES_LOCK_PID" 2>/dev/null; then
+      wait "$PR_GATES_LOCK_PID" 2>/dev/null || true
+      PR_GATES_LOCK_PID=""
+      echo "Failed to acquire the shared local heavy-check lock for prepare gates."
+      exit 1
+    fi
+    sleep 0.2
+  done
+  # Same held-lock contract check-changed uses for its children: gate stages
+  # must not re-acquire the lock the block holder already owns.
+  export OPENCLAW_TEST_HEAVY_CHECK_LOCK_HELD=1
+  export OPENCLAW_TSGO_HEAVY_CHECK_LOCK_HELD=1
+  export OPENCLAW_OXLINT_SKIP_LOCK=1
+}
+
+prepare_local_gate_workspace() {
+  pin_worktree_bundled_plugins_dir
+  acquire_pr_gates_lock
+  bootstrap_deps_if_needed
+}
+
+release_pr_gates_lock() {
+  if [ -z "${PR_GATES_LOCK_PID:-}" ]; then
+    return 0
+  fi
+  kill "$PR_GATES_LOCK_PID" 2>/dev/null || true
+  wait "$PR_GATES_LOCK_PID" 2>/dev/null || true
+  PR_GATES_LOCK_PID=""
+  rm -f "$PR_GATES_LOCK_STATUS_FILE"
+  PR_GATES_LOCK_STATUS_FILE=""
+  unset OPENCLAW_TEST_HEAVY_CHECK_LOCK_HELD OPENCLAW_TSGO_HEAVY_CHECK_LOCK_HELD OPENCLAW_OXLINT_SKIP_LOCK
+}
+
+run_remote_testbox_full_test_gate() {
+  local label="$1"
+  local log_file="$2"
+  local lease_label="$3"
+  # Same Blacksmith Testbox delegation shape check:changed uses; the worktree's
+  # own wrapper syncs this prep tree (the canonical copy would sync the primary
+  # checkout instead).
+  run_quiet_logged "$label" "$log_file" \
+    node scripts/crabbox-wrapper.mjs run \
+    --provider blacksmith-testbox \
+    --blacksmith-org openclaw \
+    --blacksmith-workflow .github/workflows/ci-check-testbox.yml \
+    --blacksmith-job check \
+    --blacksmith-ref main \
+    --idle-timeout 90m \
+    --ttl 240m \
+    --timing-json \
+    --label "$lease_label" \
+    -- env CI=1 PNPM_CONFIG_VERIFY_DEPS_BEFORE_RUN=install corepack pnpm test
+}
+
+read_remote_testbox_gate_stamp() {
+  # crabbox --timing-json emits one single-line JSON report on stderr; pick the
+  # last successful blacksmith-testbox report in the gate log as the stamp.
+  local log_file="$1"
+  jq -c -R '
+    fromjson?
+    | select(type == "object")
+    | select(.provider == "blacksmith-testbox" and .exitCode == 0 and ((.leaseId // "") | startswith("tbx_")))
+  ' "$log_file" | tail -n 1
+}
+
+read_remote_testbox_gate_run_url() {
+  # The delegated timing report currently omits actionsRunUrl, while the same
+  # run prints the canonical Actions URL as a separate line.
+  local log_file="$1"
+  local pr_url="${PR_URL:-}"
+  local expected_repo="${pr_url#https://github.com/}"
+  expected_repo="${expected_repo%%/pull/*}"
+  if [ -z "$expected_repo" ] || [ "$expected_repo" = "$pr_url" ]; then
+    expected_repo="openclaw/openclaw"
+  fi
+  local url_prefix="https://github.com/$expected_repo/actions/runs/"
+  local marker="GitHub Actions run: $url_prefix"
+  awk -v marker="$marker" -v url_prefix="$url_prefix" '
+    index($0, marker) {
+      suffix = substr($0, index($0, marker) + length(marker))
+      if (match(suffix, /^[0-9]+/)) {
+        print url_prefix substr(suffix, RSTART, RLENGTH)
+        exit
+      }
+    }
+  ' "$log_file"
+}
+
+require_remote_testbox_gate_stamp() {
+  # Runs inside $(...): report to stderr and fail the substitution so set -e
+  # aborts the caller with the message visible.
+  local log_file="$1"
+  local stamp
+  stamp=$(read_remote_testbox_gate_stamp "$log_file")
+  if [ -z "$stamp" ]; then
+    echo "Remote testbox gate passed but no successful blacksmith-testbox timing stamp was found in $log_file." >&2
+    return 1
+  fi
+  local actions_run_url
+  actions_run_url=$(read_remote_testbox_gate_run_url "$log_file")
+  if [ -n "$actions_run_url" ] && [ "$(printf '%s\n' "$stamp" | jq -r '.actionsRunUrl // empty')" = "" ]; then
+    stamp=$(printf '%s\n' "$stamp" | jq -c --arg actionsRunUrl "$actions_run_url" '. + {actionsRunUrl: $actionsRunUrl}')
+  fi
+  printf '%s\n' "$stamp"
+}
+
+write_gates_env_stamp() {
+  local pr="$1"
+  local docs_only="$2"
+  local changelog_required="$3"
+  local gates_mode="$4"
+  local last_verified_head="$5"
+  local full_gates_head="$6"
+  local hosted_gates_head="$7"
+  local remote_provider="$8"
+  local remote_lease_id="$9"
+  local remote_run_url="${10}"
+
+  # Security: shell-escape values to prevent command injection when sourced.
+  printf '%s=%q\n' \
+    PR_NUMBER "$pr" \
+    DOCS_ONLY "$docs_only" \
+    CHANGELOG_REQUIRED "$changelog_required" \
+    GATES_MODE "$gates_mode" \
+    LAST_VERIFIED_HEAD_SHA "$last_verified_head" \
+    FULL_GATES_HEAD_SHA "$full_gates_head" \
+    HOSTED_GATES_HEAD_SHA "$hosted_gates_head" \
+    REMOTE_GATES_PROVIDER "$remote_provider" \
+    REMOTE_GATES_LEASE_ID "$remote_lease_id" \
+    REMOTE_GATES_RUN_URL "$remote_run_url" \
+    GATES_PASSED_AT "$(date -u +%Y-%m-%dT%H:%M:%SZ)" \
+    > .local/gates.env
+}
+
 run_prepare_push_retry_gates() {
   local docs_only="${1:-false}"
 
@@ -40,17 +209,72 @@ run_prepare_push_retry_gates() {
     return 1
   fi
 
-  pin_worktree_bundled_plugins_dir
-  bootstrap_deps_if_needed
+  local gates_remote_mode
+  gates_remote_mode=$(resolve_pr_gates_remote_mode)
+
+  prepare_local_gate_workspace
   run_quiet_logged "pnpm build (lease-retry)" ".local/lease-retry-build.log" pnpm build
   run_quiet_logged "pnpm check (lease-retry)" ".local/lease-retry-check.log" pnpm check
-  if [ "$docs_only" != "true" ]; then
+
+  # The retry rebased the prep head, so the pre-push gates.env stamp no longer
+  # describes what these gates just verified; rewrite it for the new head so
+  # prep.md and prep.env do not attribute stale evidence to the pushed commit.
+  local retry_head
+  retry_head=$(git rev-parse HEAD)
+  local gates_mode="full"
+  local full_gates_head="$retry_head"
+  local remote_gates_provider=""
+  local remote_gates_lease_id=""
+  local remote_gates_run_url=""
+
+  if [ "$docs_only" = "true" ]; then
+    release_pr_gates_lock
+    gates_mode="docs_only"
+    # No test ran: carry the prior full-gates proof and how it was produced.
+    full_gates_head="${FULL_GATES_HEAD_SHA:-}"
+    remote_gates_provider="${REMOTE_GATES_PROVIDER:-}"
+    remote_gates_lease_id="${REMOTE_GATES_LEASE_ID:-}"
+    remote_gates_run_url="${REMOTE_GATES_RUN_URL:-}"
+  elif [ "$gates_remote_mode" = "testbox" ]; then
+    release_pr_gates_lock
+    gates_mode="remote_testbox"
+    run_remote_testbox_full_test_gate \
+      "pnpm test (lease-retry, blacksmith-testbox)" \
+      ".local/lease-retry-test.log" \
+      "pr-${PR_NUMBER:-unknown}-gates-lease-retry"
+    local retry_stamp
+    retry_stamp=$(require_remote_testbox_gate_stamp ".local/lease-retry-test.log")
+    remote_gates_provider="blacksmith-testbox"
+    remote_gates_lease_id=$(printf '%s\n' "$retry_stamp" | jq -r '.leaseId')
+    remote_gates_run_url=$(printf '%s\n' "$retry_stamp" | jq -r '.actionsRunUrl // ""')
+    echo "Remote testbox lease-retry gate stamp: $remote_gates_lease_id${remote_gates_run_url:+ ($remote_gates_run_url)}"
+  else
     run_quiet_logged "pnpm test (lease-retry)" ".local/lease-retry-test.log" pnpm test
+    release_pr_gates_lock
   fi
+
+  write_gates_env_stamp \
+    "${PR_NUMBER:-}" \
+    "$docs_only" \
+    "${CHANGELOG_REQUIRED:-false}" \
+    "$gates_mode" \
+    "$retry_head" \
+    "$full_gates_head" \
+    "" \
+    "$remote_gates_provider" \
+    "$remote_gates_lease_id" \
+    "$remote_gates_run_url"
 }
 
 prepare_gates() {
   local pr="$1"
+  local gates_remote_mode
+  gates_remote_mode=$(resolve_pr_gates_remote_mode)
+  if [ "$gates_remote_mode" = "testbox" ] && [ "${OPENCLAW_TESTBOX:-}" = "1" ]; then
+    echo "OPENCLAW_PR_GATES_REMOTE=testbox conflicts with OPENCLAW_TESTBOX=1; hosted exact-head gates already own remote proof."
+    exit 2
+  fi
+
   enter_worktree "$pr" false
 
   checkout_prep_branch "$pr"
@@ -120,11 +344,19 @@ prepare_gates() {
   current_head=$(git rev-parse HEAD)
   local previous_last_verified_head=""
   local previous_full_gates_head=""
+  local remote_gates_provider=""
+  local remote_gates_lease_id=""
+  local remote_gates_run_url=""
   if [ -s .local/gates.env ]; then
     # shellcheck disable=SC1091
     source .local/gates.env
     previous_last_verified_head="${LAST_VERIFIED_HEAD_SHA:-}"
     previous_full_gates_head="${FULL_GATES_HEAD_SHA:-}"
+    # Carried alongside FULL_GATES_HEAD_SHA: they describe how that full-suite
+    # proof was produced; a fresh full run below overwrites them.
+    remote_gates_provider="${REMOTE_GATES_PROVIDER:-}"
+    remote_gates_lease_id="${REMOTE_GATES_LEASE_ID:-}"
+    remote_gates_run_url="${REMOTE_GATES_RUN_URL:-}"
   fi
 
   local gates_mode="full"
@@ -140,6 +372,9 @@ prepare_gates() {
 
   if [ "${OPENCLAW_TESTBOX:-}" = "1" ]; then
     gates_mode="hosted_exact_head"
+    remote_gates_provider=""
+    remote_gates_lease_id=""
+    remote_gates_run_url=""
     if [ "$changelog_only" = "true" ]; then
       run_quiet_logged "git diff --check" ".local/gates-diff-check.log" git diff --check origin/main...HEAD
     fi
@@ -149,14 +384,35 @@ prepare_gates() {
     gates_mode="reused_docs_only"
     echo "Docs/changelog-only delta since last verified head $previous_last_verified_head; reusing prior gates."
   else
-    pin_worktree_bundled_plugins_dir
-    bootstrap_deps_if_needed
+    prepare_local_gate_workspace
     run_quiet_logged "pnpm build" ".local/gates-build.log" pnpm build
     run_quiet_logged "pnpm check" ".local/gates-check.log" pnpm check
 
     if [ "$docs_only" = "true" ]; then
+      release_pr_gates_lock
       gates_mode="docs_only"
+      previous_full_gates_head=""
+      remote_gates_provider=""
+      remote_gates_lease_id=""
+      remote_gates_run_url=""
       echo "Docs-only change detected with high confidence; skipping pnpm test."
+    elif [ "$gates_remote_mode" = "testbox" ]; then
+      # The full suite runs on a Blacksmith Testbox, so free the local lock
+      # for other heavy work while we wait on remote proof.
+      release_pr_gates_lock
+      gates_mode="remote_testbox"
+      echo "Running pnpm test on Blacksmith Testbox (OPENCLAW_PR_GATES_REMOTE=testbox)."
+      run_remote_testbox_full_test_gate \
+        "pnpm test (blacksmith-testbox)" \
+        ".local/gates-test.log" \
+        "pr-$pr-gates"
+      local remote_stamp
+      remote_stamp=$(require_remote_testbox_gate_stamp ".local/gates-test.log")
+      remote_gates_provider="blacksmith-testbox"
+      remote_gates_lease_id=$(printf '%s\n' "$remote_stamp" | jq -r '.leaseId')
+      remote_gates_run_url=$(printf '%s\n' "$remote_stamp" | jq -r '.actionsRunUrl // ""')
+      echo "Remote testbox gate stamp: $remote_gates_lease_id${remote_gates_run_url:+ ($remote_gates_run_url)}"
+      previous_full_gates_head="$current_head"
     else
       gates_mode="full"
       if [ -n "${OPENCLAW_VITEST_MAX_WORKERS:-}" ]; then
@@ -169,21 +425,25 @@ prepare_gates() {
         echo "Running pnpm test with host-aware scheduling defaults."
         run_quiet_logged "pnpm test" ".local/gates-test.log" pnpm test
       fi
+      release_pr_gates_lock
+      remote_gates_provider=""
+      remote_gates_lease_id=""
+      remote_gates_run_url=""
       previous_full_gates_head="$current_head"
     fi
   fi
 
-  # Security: shell-escape values to prevent command injection when sourced.
-  printf '%s=%q\n' \
-    PR_NUMBER "$pr" \
-    DOCS_ONLY "$docs_only" \
-    CHANGELOG_REQUIRED "$changelog_required" \
-    GATES_MODE "$gates_mode" \
-    LAST_VERIFIED_HEAD_SHA "$current_head" \
-    FULL_GATES_HEAD_SHA "${previous_full_gates_head:-}" \
-    HOSTED_GATES_HEAD_SHA "$hosted_gates_head" \
-    GATES_PASSED_AT "$(date -u +%Y-%m-%dT%H:%M:%SZ)" \
-    > .local/gates.env
+  write_gates_env_stamp \
+    "$pr" \
+    "$docs_only" \
+    "$changelog_required" \
+    "$gates_mode" \
+    "$current_head" \
+    "${previous_full_gates_head:-}" \
+    "$hosted_gates_head" \
+    "$remote_gates_provider" \
+    "$remote_gates_lease_id" \
+    "$remote_gates_run_url"
 
   echo "docs_only=$docs_only"
   echo "changelog_only=$changelog_only"
diff --git a/scripts/pr-lib/prepare-core.sh b/scripts/pr-lib/prepare-core.sh
index 6dd567ae339c..632073c12482 100644
--- a/scripts/pr-lib/prepare-core.sh
+++ b/scripts/pr-lib/prepare-core.sh
@@ -156,6 +156,10 @@ prepare_push() {
   push_prep_head_to_pr_branch "$pr" "$PR_HEAD" "$prep_head_sha" "$lease_sha" true "${DOCS_ONLY:-false}" "$push_result_env"
   # shellcheck disable=SC1090
   source "$push_result_env"
+  # A lease retry reruns gates for the rebased head and rewrites gates.env;
+  # re-source so prep.md/prep.env carry the stamp for the head actually pushed.
+  # shellcheck disable=SC1091
+  source .local/gates.env
   prep_head_sha="$PUSH_PREP_HEAD_SHA"
   local_prep_head_sha="$PUSH_LOCAL_PREP_HEAD_SHA"
   local mainline_base_sha
@@ -194,6 +198,11 @@ prepare_push() {
 - Gate mode: ${GATES_MODE:-unknown}.
 - Verified the remote PR head tree matches the local prep head.
 EOF_PREP
+  if [ -n "${REMOTE_GATES_LEASE_ID:-}" ]; then
+    cat >> .local/prep.md <<EOF_PREP
+- Remote testbox gate stamp: ${REMOTE_GATES_LEASE_ID}${REMOTE_GATES_RUN_URL:+ (${REMOTE_GATES_RUN_URL})}.
+EOF_PREP
+  fi
 
   # Security: shell-escape values to prevent command injection via propagated PR_HEAD.
   printf '%s=%q\n' \
diff --git a/test/scripts/pr-prepare-gates.test.ts b/test/scripts/pr-prepare-gates.test.ts
new file mode 100644
index 000000000000..fff07b09abbe
--- /dev/null
+++ b/test/scripts/pr-prepare-gates.test.ts
@@ -0,0 +1,574 @@
+// Covers the scripts/pr prepare-gates remote testbox mode and the
+// cross-worktree gate lock that serializes whole gate blocks.
+import { type ChildProcess, spawn, spawnSync } from "node:child_process";
+import { chmodSync, existsSync, mkdirSync, mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { realpathSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { afterEach, describe, expect, it } from "vitest";
+
+const repoRoot = process.cwd();
+const gateLockHelperPath = join(repoRoot, "scripts", "pr-gates-lock.mjs");
+
+const tempDirs: string[] = [];
+const children: ChildProcess[] = [];
+
+function makeTempDir(prefix: string): string {
+  // macOS os.tmpdir() is a /var -> /private/var symlink; resolve so lock and
+  // owner paths compare canonically.
+  const dir = realpathSync(mkdtempSync(join(tmpdir(), prefix)));
+  tempDirs.push(dir);
+  return dir;
+}
+
+function makeLockRepoDir(): string {
+  const dir = makeTempDir("openclaw-pr-gates-lock-");
+  mkdirSync(join(dir, ".git"), { recursive: true });
+  return dir;
+}
+
+function heavyCheckLockDir(repoDir: string): string {
+  return join(repoDir, ".git", "openclaw-local-checks", "heavy-check.lock");
+}
+
+function sanitizedEnv(overrides: NodeJS.ProcessEnv = {}): NodeJS.ProcessEnv {
+  // check:changed and gate runs export these to children; drop ambient copies
+  // so lock and mode behavior under test only sees explicit overrides.
+  const env: NodeJS.ProcessEnv = { ...process.env };
+  delete env.OPENCLAW_PR_GATES_REMOTE;
+  delete env.OPENCLAW_TESTBOX;
+  delete env.OPENCLAW_TEST_HEAVY_CHECK_LOCK_HELD;
+  delete env.OPENCLAW_TSGO_HEAVY_CHECK_LOCK_HELD;
+  delete env.OPENCLAW_OXLINT_SKIP_LOCK;
+  delete env.OPENCLAW_HEAVY_CHECK_LOCK_TIMEOUT_MS;
+  delete env.OPENCLAW_HEAVY_CHECK_LOCK_POLL_MS;
+  return { ...env, ...overrides };
+}
+
+function runGatesBash(script: string, options: { cwd?: string; env?: NodeJS.ProcessEnv } = {}) {
+  return spawnSync(
+    "bash",
+    [
+      "-c",
+      [
+        "set -euo pipefail",
+        `script_parent_dir='${repoRoot}/scripts'`,
+        `source '${repoRoot}/scripts/pr-lib/common.sh'`,
+        `source '${repoRoot}/scripts/pr-lib/gates.sh'`,
+        script,
+      ].join("\n"),
+    ],
+    {
+      cwd: options.cwd ?? repoRoot,
+      encoding: "utf8",
+      env: sanitizedEnv(options.env),
+    },
+  );
+}
+
+function spawnGateLockHolder(repoDir: string, statusFile: string, env: NodeJS.ProcessEnv = {}) {
+  const child = spawn(process.execPath, [gateLockHelperPath, "--status-file", statusFile], {
+    cwd: repoDir,
+    stdio: ["ignore", "ignore", "pipe"],
+    env: sanitizedEnv(env),
+  });
+  children.push(child);
+  return child;
+}
+
+function makeRetryRepo(): { repoDir: string; stubBin: string; headSha: string } {
+  const dir = makeTempDir("openclaw-pr-gates-retry-");
+  const repoDir = join(dir, "repo");
+  mkdirSync(repoDir);
+  for (const args of [
+    ["init", "-q"],
+    [
+      "-c",
+      "user.name=t",
+      "-c",
+      "user.email=t@example.com",
+      "commit",
+      "-q",
+      "--allow-empty",
+      "-m",
+      "retry head",
+    ],
+  ]) {
+    const result = spawnSync("git", args, { cwd: repoDir, encoding: "utf8" });
+    expect(result.status).toBe(0);
+  }
+  mkdirSync(join(repoDir, ".local"));
+
+  const stubBin = join(dir, "bin");
+  mkdirSync(stubBin);
+  writeFileSync(join(stubBin, "pnpm"), "#!/bin/sh\nexit 0\n");
+  chmodSync(join(stubBin, "pnpm"), 0o755);
+  // Route the crabbox wrapper to a canned timing report; everything else
+  // (the gate lock helper) still needs the real node.
+  writeFileSync(
+    join(stubBin, "node"),
+    [
+      "#!/bin/sh",
+      'case "$2" in',
+      `run) printf '{"provider":"blacksmith-testbox","leaseId":"tbx_retry","exitCode":0,"runStatus":"succeeded","actionsRunUrl":"https://example.test/runs/7"}\\n' >&2; exit 0;;`,
+      `*) exec '${process.execPath}' "$@";;`,
+      "esac",
+    ].join("\n"),
+  );
+  chmodSync(join(stubBin, "node"), 0o755);
+
+  const headSha = spawnSync("git", ["rev-parse", "HEAD"], {
+    cwd: repoDir,
+    encoding: "utf8",
+  }).stdout.trim();
+  return { repoDir, stubBin, headSha };
+}
+
+async function waitFor(predicate: () => boolean, timeoutMs: number): Promise<boolean> {
+  const deadline = Date.now() + timeoutMs;
+  while (Date.now() < deadline) {
+    if (predicate()) {
+      return true;
+    }
+    await new Promise((resolve) => setTimeout(resolve, 50));
+  }
+  return predicate();
+}
+
+async function waitForExit(child: ChildProcess): Promise<void> {
+  if (child.exitCode !== null || child.signalCode !== null) {
+    return;
+  }
+  await new Promise((resolve) => {
+    child.once("exit", resolve);
+  });
+}
+
+afterEach(async () => {
+  for (const child of children.splice(0)) {
+    child.kill("SIGKILL");
+    await waitForExit(child);
+  }
+  for (const dir of tempDirs.splice(0)) {
+    rmSync(dir, { recursive: true, force: true });
+  }
+});
+
+describe("resolve_pr_gates_remote_mode", () => {
+  it.each([
+    { value: undefined, expected: "local" },
+    { value: "", expected: "local" },
+    { value: "testbox", expected: "testbox" },
+  ])("resolves OPENCLAW_PR_GATES_REMOTE=$value to $expected", ({ value, expected }) => {
+    const env: NodeJS.ProcessEnv = {};
+    if (value !== undefined) {
+      env.OPENCLAW_PR_GATES_REMOTE = value;
+    }
+    const result = runGatesBash("resolve_pr_gates_remote_mode", { env });
+    expect(result.status).toBe(0);
+    expect(result.stdout.trim()).toBe(expected);
+  });
+
+  it("rejects unsupported values", () => {
+    const result = runGatesBash("resolve_pr_gates_remote_mode", {
+      env: { OPENCLAW_PR_GATES_REMOTE: "azure" },
+    });
+    expect(result.status).not.toBe(0);
+    expect(result.stderr).toContain("Unsupported OPENCLAW_PR_GATES_REMOTE=azure");
+  });
+
+  it("rejects the hosted-gates conflict before touching the worktree", () => {
+    const result = runGatesBash("prepare_gates 424242", {
+      env: { OPENCLAW_PR_GATES_REMOTE: "testbox", OPENCLAW_TESTBOX: "1" },
+    });
+    expect(result.status).toBe(2);
+    expect(result.stdout).toContain("conflicts with OPENCLAW_TESTBOX=1");
+  });
+});
+
+describe("remote testbox gate delegation", () => {
+  it("runs the full pnpm test through the worktree crabbox wrapper", () => {
+    const dir = makeTempDir("openclaw-pr-gates-remote-");
+    const stubBin = join(dir, "bin");
+    mkdirSync(stubBin);
+    writeFileSync(
+      join(stubBin, "node"),
+      [
+        "#!/bin/sh",
+        "printf 'ARG:%s\\n' \"$@\"",
+        `printf '{"provider":"blacksmith-testbox","leaseId":"tbx_stub","exitCode":0,"runStatus":"passed"}\\n' >&2`,
+      ].join("\n"),
+    );
+    chmodSync(join(stubBin, "node"), 0o755);
+
+    const workDir = join(dir, "work");
+    mkdirSync(workDir);
+    const result = runGatesBash(
+      "run_remote_testbox_full_test_gate 'pnpm test (blacksmith-testbox)' .local/gates-test.log pr-424242-gates\n" +
+        "grep '^ARG:' .local/gates-test.log | paste -sd ' ' -",
+      {
+        cwd: workDir,
+        env: { PATH: `${stubBin}:${process.env.PATH ?? ""}` },
+      },
+    );
+
+    expect(result.status).toBe(0);
+    const argLine = result.stdout
+      .split("\n")
+      .find((line) => line.includes("crabbox-wrapper.mjs"))
+      ?.replaceAll("ARG:", "");
+    expect(argLine).toBe(
+      "scripts/crabbox-wrapper.mjs run " +
+        "--provider blacksmith-testbox " +
+        "--blacksmith-org openclaw " +
+        "--blacksmith-workflow .github/workflows/ci-check-testbox.yml " +
+        "--blacksmith-job check " +
+        "--blacksmith-ref main " +
+        "--idle-timeout 90m --ttl 240m --timing-json " +
+        "--label pr-424242-gates " +
+        "-- env CI=1 PNPM_CONFIG_VERIFY_DEPS_BEFORE_RUN=install corepack pnpm test",
+    );
+  });
+
+  it("extracts the last successful blacksmith-testbox timing stamp", () => {
+    const dir = makeTempDir("openclaw-pr-gates-stamp-");
+    const log = join(dir, "gates-test.log");
+    writeFileSync(
+      log,
+      [
+        "provider=blacksmith-testbox id=tbx_first sync=delegated auth=blacksmith",
+        "GitHub Actions run: https://github.com/openclaw/openclaw/actions/runs/1234",
+        '{"not":"a stamp"}',
+        "not json at all",
+        '{"provider":"blacksmith-testbox","leaseId":"tbx_first","exitCode":1,"runStatus":"failed"}',
+        '{"provider":"blacksmith-testbox","leaseId":"tbx_final","exitCode":0,"runStatus":"passed"}',
+        "GitHub Actions run: https://github.com/openclaw/openclaw/actions/runs/9999",
+        "GitHub Actions run: https://github.com/example/other/actions/runs/8888",
+        "",
+      ].join("\n"),
+    );
+
+    const result = runGatesBash(
+      `require_remote_testbox_gate_stamp '${log}' | jq -r '[.leaseId, .actionsRunUrl] | @tsv'`,
+    );
+    expect(result.status).toBe(0);
+    expect(result.stdout.trim()).toBe(
+      "tbx_final\thttps://github.com/openclaw/openclaw/actions/runs/1234",
+    );
+  });
+
+  it("fails when the gate log has no successful stamp", () => {
+    const dir = makeTempDir("openclaw-pr-gates-stamp-");
+    const log = join(dir, "gates-test.log");
+    writeFileSync(
+      log,
+      '{"provider":"blacksmith-testbox","leaseId":"tbx_only","exitCode":1,"runStatus":"failed"}\n',
+    );
+
+    const result = runGatesBash(`require_remote_testbox_gate_stamp '${log}'`);
+    expect(result.status).not.toBe(0);
+    expect(result.stderr).toContain("no successful blacksmith-testbox timing stamp");
+  });
+});
+
+describe("lease-retry gate stamp refresh", () => {
+  it("rewrites gates.env with the fresh remote stamp for the rebased head", () => {
+    const { repoDir, stubBin, headSha } = makeRetryRepo();
+    const result = runGatesBash(
+      [
+        "PR_NUMBER=4242",
+        "CHANGELOG_REQUIRED=false",
+        "REMOTE_GATES_PROVIDER=blacksmith-testbox",
+        "REMOTE_GATES_LEASE_ID=tbx_stale",
+        "REMOTE_GATES_RUN_URL=https://example.test/runs/1",
+        "FULL_GATES_HEAD_SHA=deadbeef",
+        "run_prepare_push_retry_gates false",
+        "cat .local/gates.env",
+      ].join("\n"),
+      {
+        cwd: repoDir,
+        env: {
+          PATH: `${stubBin}:${process.env.PATH ?? ""}`,
+          OPENCLAW_PR_GATES_REMOTE: "testbox",
+        },
+      },
+    );
+
+    expect(result.status).toBe(0);
+    expect(result.stdout).toContain("GATES_MODE=remote_testbox");
+    expect(result.stdout).toContain("REMOTE_GATES_LEASE_ID=tbx_retry");
+    expect(result.stdout).toContain(`LAST_VERIFIED_HEAD_SHA=${headSha}`);
+    expect(result.stdout).toContain(`FULL_GATES_HEAD_SHA=${headSha}`);
+    expect(result.stdout).not.toContain("tbx_stale");
+  });
+
+  it("clears a stale remote stamp when the retry test ran locally", () => {
+    const { repoDir, stubBin, headSha } = makeRetryRepo();
+    const result = runGatesBash(
+      [
+        "PR_NUMBER=4242",
+        "CHANGELOG_REQUIRED=false",
+        "REMOTE_GATES_PROVIDER=blacksmith-testbox",
+        "REMOTE_GATES_LEASE_ID=tbx_stale",
+        "run_prepare_push_retry_gates false",
+        "cat .local/gates.env",
+      ].join("\n"),
+      {
+        cwd: repoDir,
+        env: { PATH: `${stubBin}:${process.env.PATH ?? ""}` },
+      },
+    );
+
+    expect(result.status).toBe(0);
+    expect(result.stdout).toContain("GATES_MODE=full");
+    expect(result.stdout).toContain("REMOTE_GATES_LEASE_ID=''");
+    expect(result.stdout).toContain(`FULL_GATES_HEAD_SHA=${headSha}`);
+    expect(result.stdout).not.toContain("tbx_stale");
+  });
+});
+
+describe("prepare gate stamp transitions", () => {
+  it("clears remote stamps when fresh docs-only gates do not reuse prior proof", () => {
+    const { repoDir } = makeRetryRepo();
+    spawnSync("git", ["update-ref", "refs/remotes/origin/main", "HEAD"], { cwd: repoDir });
+    mkdirSync(join(repoDir, "docs"), { recursive: true });
+    writeFileSync(join(repoDir, "docs", "proof.md"), "fresh docs\n");
+    spawnSync("git", ["add", "docs/proof.md"], { cwd: repoDir });
+    spawnSync(
+      "git",
+      ["-c", "user.name=t", "-c", "user.email=t@example.com", "commit", "-qm", "docs"],
+      { cwd: repoDir },
+    );
+    writeFileSync(join(repoDir, ".local", "pr-meta.env"), "PR_AUTHOR=steipete\n");
+    writeFileSync(
+      join(repoDir, ".local", "gates.env"),
+      [
+        "LAST_VERIFIED_HEAD_SHA=deadbeef",
+        "FULL_GATES_HEAD_SHA=deadbeef",
+        "REMOTE_GATES_PROVIDER=blacksmith-testbox",
+        "REMOTE_GATES_LEASE_ID=tbx_stale",
+        "REMOTE_GATES_RUN_URL=https://example.test/runs/1",
+        "",
+      ].join("\n"),
+    );
+
+    const result = runGatesBash(
+      [
+        "enter_worktree() { :; }",
+        "checkout_prep_branch() { :; }",
+        "path_is_docsish() { return 0; }",
+        "changelog_required_for_changed_files() { return 1; }",
+        "prepare_local_gate_workspace() { :; }",
+        "run_quiet_logged() { :; }",
+        "release_pr_gates_lock() { :; }",
+        "prepare_gates 4242",
+        "cat .local/gates.env",
+      ].join("\n"),
+      { cwd: repoDir },
+    );
+
+    expect(result.status).toBe(0);
+    expect(result.stdout).toContain("GATES_MODE=docs_only");
+    expect(result.stdout).toContain("FULL_GATES_HEAD_SHA=''");
+    expect(result.stdout).toContain("REMOTE_GATES_LEASE_ID=''");
+    expect(result.stdout).not.toContain("tbx_stale");
+  });
+
+  it("clears remote stamps when hosted exact-head gates replace remote proof", () => {
+    const { repoDir } = makeRetryRepo();
+    spawnSync("git", ["update-ref", "refs/remotes/origin/main", "HEAD"], { cwd: repoDir });
+    writeFileSync(join(repoDir, "changed.ts"), "export {};\n");
+    spawnSync("git", ["add", "changed.ts"], { cwd: repoDir });
+    spawnSync(
+      "git",
+      ["-c", "user.name=t", "-c", "user.email=t@example.com", "commit", "-qm", "change"],
+      { cwd: repoDir },
+    );
+    writeFileSync(join(repoDir, ".local", "pr-meta.env"), "PR_AUTHOR=steipete\n");
+    writeFileSync(
+      join(repoDir, ".local", "gates.env"),
+      [
+        "LAST_VERIFIED_HEAD_SHA=deadbeef",
+        "FULL_GATES_HEAD_SHA=deadbeef",
+        "REMOTE_GATES_PROVIDER=blacksmith-testbox",
+        "REMOTE_GATES_LEASE_ID=tbx_stale",
+        "REMOTE_GATES_RUN_URL=https://example.test/runs/1",
+        "",
+      ].join("\n"),
+    );
+
+    const result = runGatesBash(
+      [
+        "enter_worktree() { :; }",
+        "checkout_prep_branch() { :; }",
+        "path_is_docsish() { return 1; }",
+        "changelog_required_for_changed_files() { return 1; }",
+        "run_hosted_prepare_gates() { :; }",
+        "prepare_gates 4242",
+        "cat .local/gates.env",
+      ].join("\n"),
+      { cwd: repoDir, env: { OPENCLAW_TESTBOX: "1" } },
+    );
+
+    expect(result.status).toBe(0);
+    expect(result.stdout).toContain("GATES_MODE=hosted_exact_head");
+    expect(result.stdout).toContain("REMOTE_GATES_LEASE_ID=''");
+    expect(result.stdout).not.toContain("tbx_stale");
+  });
+});
+
+describe("pr-gates-lock helper", () => {
+  it("acquires the shared heavy-check lock and releases it on SIGTERM", async () => {
+    const repoDir = makeLockRepoDir();
+    const statusFile = join(repoDir, "status");
+    const holder = spawnGateLockHolder(repoDir, statusFile);
+
+    expect(await waitFor(() => existsSync(statusFile), 5_000)).toBe(true);
+    expect(existsSync(heavyCheckLockDir(repoDir))).toBe(true);
+
+    holder.kill("SIGTERM");
+    await waitForExit(holder);
+    expect(await waitFor(() => !existsSync(heavyCheckLockDir(repoDir)), 5_000)).toBe(true);
+  });
+
+  it("queues behind an existing holder and acquires after it exits", async () => {
+    const repoDir = makeLockRepoDir();
+    const firstStatus = join(repoDir, "status-first");
+    const secondStatus = join(repoDir, "status-second");
+
+    const first = spawnGateLockHolder(repoDir, firstStatus);
+    expect(await waitFor(() => existsSync(firstStatus), 5_000)).toBe(true);
+
+    const second = spawnGateLockHolder(repoDir, secondStatus, {
+      OPENCLAW_HEAVY_CHECK_LOCK_POLL_MS: "50",
+    });
+    await new Promise((resolve) => setTimeout(resolve, 400));
+    expect(existsSync(secondStatus)).toBe(false);
+
+    first.kill("SIGTERM");
+    await waitForExit(first);
+    expect(await waitFor(() => existsSync(secondStatus), 5_000)).toBe(true);
+
+    second.kill("SIGTERM");
+    await waitForExit(second);
+    expect(await waitFor(() => !existsSync(heavyCheckLockDir(repoDir)), 5_000)).toBe(true);
+  });
+
+  it("fails instead of holding when the wait times out", async () => {
+    const repoDir = makeLockRepoDir();
+    const lockDir = heavyCheckLockDir(repoDir);
+    mkdirSync(lockDir, { recursive: true });
+    // Owner pid must be alive or the helper reclaims the stale lock.
+    writeFileSync(
+      join(lockDir, "owner.json"),
+      `${JSON.stringify({ pid: process.pid, tool: "test-holder", cwd: repoDir })}\n`,
+    );
+
+    const statusFile = join(repoDir, "status");
+    const holder = spawnGateLockHolder(repoDir, statusFile, {
+      OPENCLAW_HEAVY_CHECK_LOCK_TIMEOUT_MS: "200",
+      OPENCLAW_HEAVY_CHECK_LOCK_POLL_MS: "50",
+    });
+    await waitForExit(holder);
+
+    expect(holder.exitCode).not.toBe(0);
+    expect(existsSync(statusFile)).toBe(false);
+  });
+
+  it("releases the lock when the parent process dies", async () => {
+    const repoDir = makeLockRepoDir();
+    const statusFile = join(repoDir, "status");
+    const parent = spawn(
+      "bash",
+      [
+        "-c",
+        `node '${gateLockHelperPath}' --status-file '${statusFile}' 2>/dev/null & ` +
+          `while [ ! -s '${statusFile}' ]; do sleep 0.05; done`,
+      ],
+      { cwd: repoDir, stdio: "ignore", env: sanitizedEnv() },
+    );
+    children.push(parent);
+    await waitForExit(parent);
+
+    expect(existsSync(statusFile)).toBe(true);
+    expect(await waitFor(() => !existsSync(heavyCheckLockDir(repoDir)), 8_000)).toBe(true);
+  });
+});
+
+describe("gates.sh gate lock plumbing", () => {
+  it("acquires the block lock before dependency bootstrap", () => {
+    const result = runGatesBash(
+      [
+        "events=$(mktemp)",
+        'pin_worktree_bundled_plugins_dir() { echo pin >> "$events"; }',
+        'acquire_pr_gates_lock() { echo lock >> "$events"; }',
+        'bootstrap_deps_if_needed() { echo bootstrap >> "$events"; }',
+        "prepare_local_gate_workspace",
+        'cat "$events"',
+      ].join("\n"),
+    );
+
+    expect(result.status).toBe(0);
+    expect(result.stdout.trim().split("\n")).toEqual(["pin", "lock", "bootstrap"]);
+  });
+
+  it("exports the held-lock contract while holding and clears it on release", () => {
+    const repoDir = makeLockRepoDir();
+    const result = runGatesBash(
+      [
+        "acquire_pr_gates_lock",
+        'echo "held=${OPENCLAW_TEST_HEAVY_CHECK_LOCK_HELD:-unset},${OPENCLAW_TSGO_HEAVY_CHECK_LOCK_HELD:-unset},${OPENCLAW_OXLINT_SKIP_LOCK:-unset}"',
+        "jq -r .tool .git/openclaw-local-checks/heavy-check.lock/owner.json",
+        "release_pr_gates_lock",
+        'echo "released=${OPENCLAW_TEST_HEAVY_CHECK_LOCK_HELD:-unset}"',
+        '[ -d .git/openclaw-local-checks/heavy-check.lock ] && echo "lock=held" || echo "lock=free"',
+      ].join("\n"),
+      { cwd: repoDir },
+    );
+
+    expect(result.status).toBe(0);
+    expect(result.stdout).toContain("held=1,1,1");
+    expect(result.stdout).toContain("pr-gates");
+    expect(result.stdout).toContain("released=unset");
+    expect(result.stdout).toContain("lock=free");
+  });
+
+  it("skips acquisition when a parent already holds the lock", () => {
+    const repoDir = makeLockRepoDir();
+    const result = runGatesBash(
+      [
+        "acquire_pr_gates_lock",
+        '[ -d .git/openclaw-local-checks/heavy-check.lock ] && echo "lock=held" || echo "lock=free"',
+        'echo "helper_pid=${PR_GATES_LOCK_PID:-none}"',
+      ].join("\n"),
+      { cwd: repoDir, env: { OPENCLAW_TEST_HEAVY_CHECK_LOCK_HELD: "1" } },
+    );
+
+    expect(result.status).toBe(0);
+    expect(result.stdout).toContain("lock=free");
+    expect(result.stdout).toContain("helper_pid=none");
+  });
+
+  it("fails the gate run when the lock wait times out", () => {
+    const repoDir = makeLockRepoDir();
+    const lockDir = heavyCheckLockDir(repoDir);
+    mkdirSync(lockDir, { recursive: true });
+    writeFileSync(
+      join(lockDir, "owner.json"),
+      `${JSON.stringify({ pid: process.pid, tool: "test-holder", cwd: repoDir })}\n`,
+    );
+
+    const result = runGatesBash("acquire_pr_gates_lock", {
+      cwd: repoDir,
+      env: {
+        OPENCLAW_HEAVY_CHECK_LOCK_TIMEOUT_MS: "200",
+        OPENCLAW_HEAVY_CHECK_LOCK_POLL_MS: "50",
+      },
+    });
+
+    expect(result.status).toBe(1);
+    expect(result.stdout).toContain(
+      "Failed to acquire the shared local heavy-check lock for prepare gates.",
+    );
+  });
+});