diff --git a/AGENTS.md b/AGENTS.md
index 5f715abc1b0..28d1b9cc2a6 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -208,7 +208,10 @@
   - Fresh Tahoe snapshot current reality: `brew` exists, `node` may not be on `PATH` in noninteractive guest exec. Use absolute `/opt/homebrew/bin/node` for repo/CLI runs when needed.
   - Preferred automation entrypoint: `pnpm test:parallels:macos`. It restores the snapshot most closely matching `macOS 26.3.1 fresh`, serves the current `main` tarball from the host, then runs fresh-install and latest-release-to-main smoke lanes.
   - Gateway verification in smoke runs should use `openclaw gateway status --deep --require-rpc`, not plain `--deep`, so probe failures go non-zero.
+  - Latest-release pre-upgrade diagnostics still need compatibility fallback: stable `2026.3.12` does not know `--require-rpc`, so precheck status dumps should fall back to plain `gateway status --deep` until the guest is upgraded.
   - Harness output: pass `--json` for machine-readable summary; per-phase logs land under `/tmp/openclaw-parallels-smoke.*`.
+  - All-OS parallel runs should share the host `dist` build via `/tmp/openclaw-parallels-build.lock` instead of rebuilding three times.
+  - Current expected outcome on latest stable pre-upgrade: `precheck=latest-ref-fail` is normal on `2026.3.12`; treat it as a baseline signal, not a regression, unless the post-upgrade `main` lane also fails.
   - Fresh host-served tgz install: restore fresh snapshot, install tgz as guest root with `HOME=/var/root`, then run onboarding as the desktop user via `prlctl exec --current-user`.
   - For `openclaw onboard --non-interactive --secret-input-mode ref --install-daemon`, expect env-backed auth-profile refs (for example `OPENAI_API_KEY`) to be copied into the service env at install time; this path was fixed and should stay green.
   - Don’t run local + gateway agent turns in parallel on the same fresh workspace/session; they can collide on the session lock. Run sequentially.
@@ -216,10 +219,13 @@
 - Parallels Windows smoke playbook:
   - Preferred automation entrypoint: `pnpm test:parallels:windows`. It restores the snapshot most closely matching `pre-openclaw-native-e2e-2026-03-12`, serves the current `main` tarball from the host, then runs fresh-install and latest-release-to-main smoke lanes.
   - Gateway verification in smoke runs should use `openclaw gateway status --deep --require-rpc`, not plain `--deep`, so probe failures go non-zero.
+  - Latest-release pre-upgrade diagnostics still need compatibility fallback: stable `2026.3.12` does not know `--require-rpc`, so precheck status dumps should fall back to plain `gateway status --deep` until the guest is upgraded.
   - Always use `prlctl exec --current-user` for Windows guest runs; plain `prlctl exec` lands in `NT AUTHORITY\SYSTEM` and does not match the real desktop-user install path.
   - Prefer explicit `npm.cmd` / `openclaw.cmd`. Bare `npm` / `openclaw` in PowerShell can hit the `.ps1` shim and fail under restrictive execution policy.
   - Use PowerShell only as the transport (`powershell.exe -NoProfile -ExecutionPolicy Bypass`) and call the `.cmd` shims explicitly from inside it.
   - Harness output: pass `--json` for machine-readable summary; per-phase logs land under `/tmp/openclaw-parallels-windows.*`.
+  - Current expected outcome on latest stable pre-upgrade: `precheck=latest-ref-fail` is normal on `2026.3.12`; treat it as a baseline signal, not a regression, unless the post-upgrade `main` lane also fails.
+  - Keep Windows onboarding/status text ASCII-clean in logs. Fancy punctuation in banners shows up as mojibake through the current guest PowerShell capture path.
 - Parallels Linux smoke playbook:
   - Preferred automation entrypoint: `pnpm test:parallels:linux`. It restores the snapshot most closely matching `fresh` on `Ubuntu 24.04.3 ARM64`, serves the current `main` tarball from the host, then runs fresh-install and latest-release-to-main smoke lanes.
   - Use plain `prlctl exec` on this snapshot. `--current-user` is not the right transport there.
@@ -231,6 +237,7 @@
   - When you do run Linux gateway checks manually from an interactive guest shell, use `openclaw gateway status --deep --require-rpc` so an RPC miss is a hard failure.
   - Prefer direct argv guest commands for fetch/install steps (`curl`, `npm install -g`, `openclaw ...`) over nested `bash -lc` quoting; Linux guest quoting through Parallels was the flaky part.
   - Harness output: pass `--json` for machine-readable summary; per-phase logs land under `/tmp/openclaw-parallels-linux.*`.
+  - Current expected outcome on Linux smoke: fresh + upgrade should pass installer and `agent --local`; gateway remains `skipped-no-detached-linux-gateway` on this snapshot and should not be treated as a regression by itself.
 - Never edit `node_modules` (global/Homebrew/npm/git installs too). Updates overwrite. Skill notes go in `tools.md` or `AGENTS.md`.
 - When adding a new `AGENTS.md` anywhere in the repo, also add a `CLAUDE.md` symlink pointing to it (example: `ln -s AGENTS.md CLAUDE.md`).
 - Signal: "update fly" => `fly ssh console -a flawd-bot -C "bash -lc 'cd /data/clawd/openclaw && git pull --rebase origin main'"` then `fly machines restart e825232f34d058 -a flawd-bot`.
diff --git a/scripts/e2e/parallels-linux-smoke.sh b/scripts/e2e/parallels-linux-smoke.sh
index 120a8290bc2..dfed00bf89d 100644
--- a/scripts/e2e/parallels-linux-smoke.sh
+++ b/scripts/e2e/parallels-linux-smoke.sh
@@ -17,6 +17,7 @@ MAIN_TGZ_DIR="$(mktemp -d)"
 MAIN_TGZ_PATH=""
 SERVER_PID=""
 RUN_DIR="$(mktemp -d /tmp/openclaw-parallels-linux.XXXXXX)"
+BUILD_LOCK_DIR="${TMPDIR:-/tmp}/openclaw-parallels-build.lock"
 
 TIMEOUT_SNAPSHOT_S=180
 TIMEOUT_BOOTSTRAP_S=600
@@ -260,16 +261,41 @@ else:
 PY
 }
 
+acquire_build_lock() {
+  local owner_pid=""
+  while ! mkdir "$BUILD_LOCK_DIR" 2>/dev/null; do
+    if [[ -f "$BUILD_LOCK_DIR/pid" ]]; then
+      owner_pid="$(cat "$BUILD_LOCK_DIR/pid" 2>/dev/null || true)"
+      if [[ -n "$owner_pid" ]] && ! kill -0 "$owner_pid" >/dev/null 2>&1; then
+        warn "Removing stale Parallels build lock"
+        rm -rf "$BUILD_LOCK_DIR"
+        continue
+      fi
+    fi
+    sleep 1
+  done
+  printf '%s\n' "$$" >"$BUILD_LOCK_DIR/pid"
+}
+
+release_build_lock() {
+  if [[ -d "$BUILD_LOCK_DIR" ]]; then
+    rm -rf "$BUILD_LOCK_DIR"
+  fi
+}
+
 ensure_current_build() {
   local head build_commit
+  acquire_build_lock
   head="$(git rev-parse HEAD)"
   build_commit="$(current_build_commit)"
   if [[ "$build_commit" == "$head" ]]; then
+    release_build_lock
     return
   fi
   say "Build dist for current head"
   pnpm build
   build_commit="$(current_build_commit)"
+  release_build_lock
   [[ "$build_commit" == "$head" ]] || die "dist/build-info.json still does not match HEAD after build"
 }
 
diff --git a/scripts/e2e/parallels-macos-smoke.sh b/scripts/e2e/parallels-macos-smoke.sh
index c85f3d237ec..4de2fb19ae3 100644
--- a/scripts/e2e/parallels-macos-smoke.sh
+++ b/scripts/e2e/parallels-macos-smoke.sh
@@ -24,6 +24,7 @@ MAIN_TGZ_DIR="$(mktemp -d)"
 MAIN_TGZ_PATH=""
 SERVER_PID=""
 RUN_DIR="$(mktemp -d /tmp/openclaw-parallels-smoke.XXXXXX)"
+BUILD_LOCK_DIR="${TMPDIR:-/tmp}/openclaw-parallels-build.lock"
 
 TIMEOUT_INSTALL_S=900
 TIMEOUT_VERIFY_S=60
@@ -397,16 +398,41 @@ else:
 PY
 }
 
+acquire_build_lock() {
+  local owner_pid=""
+  while ! mkdir "$BUILD_LOCK_DIR" 2>/dev/null; do
+    if [[ -f "$BUILD_LOCK_DIR/pid" ]]; then
+      owner_pid="$(cat "$BUILD_LOCK_DIR/pid" 2>/dev/null || true)"
+      if [[ -n "$owner_pid" ]] && ! kill -0 "$owner_pid" >/dev/null 2>&1; then
+        warn "Removing stale Parallels build lock"
+        rm -rf "$BUILD_LOCK_DIR"
+        continue
+      fi
+    fi
+    sleep 1
+  done
+  printf '%s\n' "$$" >"$BUILD_LOCK_DIR/pid"
+}
+
+release_build_lock() {
+  if [[ -d "$BUILD_LOCK_DIR" ]]; then
+    rm -rf "$BUILD_LOCK_DIR"
+  fi
+}
+
 ensure_current_build() {
   local head build_commit
+  acquire_build_lock
   head="$(git rev-parse HEAD)"
   build_commit="$(current_build_commit)"
   if [[ "$build_commit" == "$head" ]]; then
+    release_build_lock
     return
   fi
   say "Build dist for current head"
   pnpm build
   build_commit="$(current_build_commit)"
+  release_build_lock
   [[ "$build_commit" == "$head" ]] || die "dist/build-info.json still does not match HEAD after build"
 }
 
@@ -465,6 +491,14 @@ verify_gateway() {
   guest_current_user_exec "$GUEST_NODE_BIN" "$GUEST_OPENCLAW_ENTRY" gateway status --deep --require-rpc
 }
 
+show_gateway_status_compat() {
+  if guest_current_user_exec "$GUEST_NODE_BIN" "$GUEST_OPENCLAW_ENTRY" gateway status --help | grep -Fq -- "--require-rpc"; then
+    guest_current_user_exec "$GUEST_NODE_BIN" "$GUEST_OPENCLAW_ENTRY" gateway status --deep --require-rpc
+    return
+  fi
+  guest_current_user_exec "$GUEST_NODE_BIN" "$GUEST_OPENCLAW_ENTRY" gateway status --deep
+}
+
 verify_turn() {
   guest_current_user_exec "$GUEST_NODE_BIN" "$GUEST_OPENCLAW_ENTRY" agent --agent main --message ping --json
 }
@@ -587,7 +621,7 @@ capture_latest_ref_failure() {
   fi
   warn "Latest release ref-mode onboard failed pre-upgrade"
   set +e
-  guest_current_user_exec "$GUEST_NODE_BIN" "$GUEST_OPENCLAW_ENTRY" gateway status --deep --require-rpc || true
+  show_gateway_status_compat || true
   set -e
   return 1
 }
diff --git a/scripts/e2e/parallels-windows-smoke.sh b/scripts/e2e/parallels-windows-smoke.sh
index 548d3d033aa..3b9ec366790 100644
--- a/scripts/e2e/parallels-windows-smoke.sh
+++ b/scripts/e2e/parallels-windows-smoke.sh
@@ -20,6 +20,7 @@ MINGIT_ZIP_PATH=""
 MINGIT_ZIP_NAME=""
 SERVER_PID=""
 RUN_DIR="$(mktemp -d /tmp/openclaw-parallels-windows.XXXXXX)"
+BUILD_LOCK_DIR="${TMPDIR:-/tmp}/openclaw-parallels-build.lock"
 
 TIMEOUT_SNAPSHOT_S=240
 TIMEOUT_INSTALL_S=1200
@@ -509,16 +510,41 @@ else:
 PY
 }
 
+acquire_build_lock() {
+  local owner_pid=""
+  while ! mkdir "$BUILD_LOCK_DIR" 2>/dev/null; do
+    if [[ -f "$BUILD_LOCK_DIR/pid" ]]; then
+      owner_pid="$(cat "$BUILD_LOCK_DIR/pid" 2>/dev/null || true)"
+      if [[ -n "$owner_pid" ]] && ! kill -0 "$owner_pid" >/dev/null 2>&1; then
+        warn "Removing stale Parallels build lock"
+        rm -rf "$BUILD_LOCK_DIR"
+        continue
+      fi
+    fi
+    sleep 1
+  done
+  printf '%s\n' "$$" >"$BUILD_LOCK_DIR/pid"
+}
+
+release_build_lock() {
+  if [[ -d "$BUILD_LOCK_DIR" ]]; then
+    rm -rf "$BUILD_LOCK_DIR"
+  fi
+}
+
 ensure_current_build() {
   local head build_commit
+  acquire_build_lock
   head="$(git rev-parse HEAD)"
   build_commit="$(current_build_commit)"
   if [[ "$build_commit" == "$head" ]]; then
+    release_build_lock
     return
   fi
   say "Build dist for current head"
   pnpm build
   build_commit="$(current_build_commit)"
+  release_build_lock
   [[ "$build_commit" == "$head" ]] || die "dist/build-info.json still does not match HEAD after build"
 }
 
@@ -678,6 +704,14 @@ verify_gateway() {
   guest_run_openclaw "" "" gateway status --deep --require-rpc
 }
 
+show_gateway_status_compat() {
+  if guest_run_openclaw "" "" gateway status --help | grep -Fq -- "--require-rpc"; then
+    guest_run_openclaw "" "" gateway status --deep --require-rpc
+    return
+  fi
+  guest_run_openclaw "" "" gateway status --deep
+}
+
 verify_turn() {
   guest_run_openclaw "" "" agent --agent main --message ping --json
 }
@@ -693,7 +727,7 @@ capture_latest_ref_failure() {
   fi
   warn "Latest release ref-mode onboard failed pre-upgrade"
   set +e
-  verify_gateway || true
+  show_gateway_status_compat || true
   set -e
   return 1
 }