diff --git a/MobileGL/MG_Test/Wire/RemoteClientE1Controls.inc b/MobileGL/MG_Test/Wire/RemoteClientE1Controls.inc
new file mode 100644
index 00000000..e08718bc
--- /dev/null
+++ b/MobileGL/MG_Test/Wire/RemoteClientE1Controls.inc
@@ -0,0 +1,109 @@
+// E1: real transport wait boundaries, with a peer that cannot complete until
+// either the client parks or its emission has already returned. No GPU or
+// scheduling-delay assumption decides whether the wait was observed.
+#if MGTEST_HAVE_FORK
+namespace {
+struct E1BoundaryPeer : Codec::WireVerbSink {
+    BudgetBell& bell;
+    std::atomic<Bool> clientReturned{false};
+    std::atomic<Uint32> seen{0};
+    MGPWireOp expected;
+    explicit E1BoundaryPeer(BudgetBell& value, MGPWireOp op) : bell(value), expected(op) {}
+
+    Bool Apply(MGPWireOp op) {
+        if (op != expected) ::_exit(84);
+        ++seen;
+        while (!bell.entered.load() && !clientReturned.load()) std::this_thread::yield();
+        return true;
+    }
+    Bool OnGenerateMipmap(const MGPMipPlan&) override { return Apply(MGPWireOp::GenerateMipmap); }
+    Bool OnClear(const MGPClear&) override { return Apply(MGPWireOp::Clear); }
+    void Install() {
+        if (Srv::ServerLoopInstance().RunProbeOnApplyThreadForTesting([](void* self) {
+            auto& decoder = Srv::ServerSessionInstance().Applier().*PeerMember(DecoderTag{});
+            decoder.SetVerbSink(static_cast<E1BoundaryPeer*>(self));
+            return MOBILEGL_OK;
+        }, this) != MOBILEGL_OK) ::_exit(82);
+    }
+};
+
+void CheckE1Boundary(Bool serverCap, MGPWireOp op, Bool expectWait, const char* diagnostic) {
+    const auto child = RunInChild([=] {
+        ::alarm(15);
+        const char* barrier = std::getenv("MOBILEGL_IPC_VERB_BARRIER");
+        if (barrier && std::strcmp(barrier, "0") && std::strcmp(barrier, "1")) ::_exit(80);
+        MG_Config::Ipc.VerbBarrier = barrier ? static_cast<Uint32>(barrier[0] - '0') : 1;
+        MG_Config::Ipc.BatchWaits = 1;
+        MG_Config::Ipc.RunAhead = 1;
+        MG_Config::Ipc.SpinUs = 0;
+        MG_Config::Transport = MG_Config::TransportMode::InProcess;
+        const Uint64 caps = serverCap ? static_cast<Uint64>(kCapRunAheadApply) : 0;
+        Srv::ServerSessionInstance().SetCapabilityBits(caps);
+        Srv::ServerSessionInstance().SetConsumedSubsystems(kMGPipeSubsystemsMigratedAtP4a);
+        AdoptSnapshot(MakeSnapshot(kMGPipeSubsystemsMigratedAtP4a, caps));
+        auto& session = ClientSessionInstance();
+        if (session.Start(MG_Config::TransportMode::InProcess, {}) != MOBILEGL_OK) ::_exit(81);
+        auto& producer = session.Producer();
+        BudgetBell bell(producer.SelfDoorbell());
+        E1BoundaryPeer peer(bell, op);
+        peer.Install();
+        const Uint64 before = session.Control()->submittedSeq.load();
+        producer.*PeerMember(ProducerBellTag{}) = &bell;
+        const MGPMipPlan mip{};
+        const MGPClear clear{};
+        const Uint64 seq = op == MGPWireOp::GenerateMipmap
+            ? session.EmitAndWait(op, &mip, sizeof(mip), nullptr, 0, nullptr, 0, nullptr)
+            : session.EmitAndWait(op, &clear, sizeof(clear), nullptr, 0, nullptr, 0, nullptr);
+        // Observe BEFORE allowing the peer to complete a non-waiting emission.
+        const Bool parked = bell.entered.load();
+        const Bool appliedBeforeReturn = session.Control()->appliedSeq.load() >= seq;
+        peer.clientReturned.store(true);
+        producer.*PeerMember(ProducerBellTag{}) = bell.original;
+        if (session.WaitForApplied(seq, 2000) != Transport::SessionWait::Reached) ::_exit(85);
+        if (seq <= before || peer.seen.load() != 1 || session.Control()->appliedSeq.load() < seq) ::_exit(86);
+        const Bool correct = expectWait ? parked && appliedBeforeReturn : !parked && !appliedBeforeReturn;
+        std::printf("E1 observation: op=%s cap=%u barrier=%u parked=%u applied_before_return=%u emitted=1 peer_seen=1\n",
+                    op == MGPWireOp::GenerateMipmap ? "GenerateMipmap" : "Clear",
+                    static_cast<unsigned>(serverCap), MG_Config::Ipc.VerbBarrier,
+                    static_cast<unsigned>(parked), static_cast<unsigned>(appliedBeforeReturn));
+        std::fflush(stdout);
+        session.Stop();
+        ::_exit(correct ? 0 : 101);
+    });
+    ASSERT_TRUE(WIFEXITED(child.Status)) << DescribeStatus(child) << '\n' << child.Log;
+    const int code = WEXITSTATUS(child.Status);
+    ASSERT_TRUE(code == 0 || code == 101) << "E1 probe/setup failed: " << DescribeStatus(child) << '\n' << child.Log;
+    EXPECT_EQ(code, 0) << diagnostic;
+}
+} // namespace
+#endif
+
+TEST(RemoteWaitBoundaryControl, AppliedClassWaitsWithRunAheadCap) {
+#if MGTEST_HAVE_FORK
+    ASSERT_EQ(MGPipeWaitClassFor(MGPWireOp::GenerateMipmap), kWaitApplied);
+    CheckE1Boundary(true, MGPWireOp::GenerateMipmap, true,
+                    "E1 wait boundary: GenerateMipmap returned before apply");
+#else
+    GTEST_SKIP() << "E1 requires POSIX child isolation";
+#endif
+}
+
+TEST(RemoteWaitBoundaryControl, MissingServerCapKeepsClearLockstep) {
+#if MGTEST_HAVE_FORK
+    ASSERT_EQ(MGPipeWaitClassFor(MGPWireOp::Clear), kWaitNone);
+    CheckE1Boundary(false, MGPWireOp::Clear, true,
+                    "E1 wait boundary: Clear without server cap returned before apply");
+#else
+    GTEST_SKIP() << "E1 requires POSIX child isolation";
+#endif
+}
+
+TEST(RemoteWaitBoundaryControl, ServerCapAllowsClearToRunAhead) {
+#if MGTEST_HAVE_FORK
+    ASSERT_EQ(MGPipeWaitClassFor(MGPWireOp::Clear), kWaitNone);
+    CheckE1Boundary(true, MGPWireOp::Clear, false,
+                    "E1 positive boundary: Clear with server cap waited for apply");
+#else
+    GTEST_SKIP() << "E1 requires POSIX child isolation";
+#endif
+}
diff --git a/MobileGL/MG_Test/Wire/RemoteClientTest.cpp b/MobileGL/MG_Test/Wire/RemoteClientTest.cpp
index a938a23e..ad26faf5 100644
--- a/MobileGL/MG_Test/Wire/RemoteClientTest.cpp
+++ b/MobileGL/MG_Test/Wire/RemoteClientTest.cpp
@@ -2710,6 +2710,8 @@ TEST(RemoteRunAhead, OnlyTheTextureHalfOfResourceSubDataWantsItsReply) {
 }
 
 
+#include "RemoteClientE1Controls.inc"
+
 int main(int argc, char** argv) {
     namespace fs = std::filesystem;
     const fs::path path =
diff --git a/scripts/ci/control_smoke_test.sh b/scripts/ci/control_smoke_test.sh
index 324ae64d..8ef470c8 100644
--- a/scripts/ci/control_smoke_test.sh
+++ b/scripts/ci/control_smoke_test.sh
@@ -87,6 +87,12 @@ expect FAILED "the knob leaves the selection green"          -- run_split green
 expect FAILED "the baseline is already red"                  -- run_split red-baseline
 # P5 is complete: losing the runtime implementation must no longer disarm the gate.
 expect FAILED "every split entry skipped (implementation lost)" -- run_split all-skipped
+expect FAILED "E1 missing boundary probes"                  -- run_split e1-empty
+expect FAILED "E1 own baseline is already red"               -- run_split e1-red-baseline
+expect FAILED "E1 restored boundary remains red"             -- run_split e1-restore-red
+expect FAILED "E1 record never reaches the peer"             -- run_split e1-no-peer
+expect FAILED "E1 observed no real emission"                 -- run_split e1-no-emit
+expect FAILED "E1 incorrectly waits every record"            -- run_split e1-waitall
 
 echo
 echo "=== the retrace lane's pull-library control (scripts/ci/retrace_pull_library_control.sh)"
diff --git a/scripts/ci/redcheck_control_smoke_test.sh b/scripts/ci/redcheck_control_smoke_test.sh
index 61e71489..8114e936 100755
--- a/scripts/ci/redcheck_control_smoke_test.sh
+++ b/scripts/ci/redcheck_control_smoke_test.sh
@@ -13,12 +13,14 @@ set -u
 HERE="$(cd "$(dirname "$0")" && pwd)"
 WORK="$(mktemp -d)" || exit 1
 HELPER="${HERE}/../../MobileGL/MG_IntegrationTest/Harness/split_log_paths.py"
-trap 'cp "${WORK}/split.orig" "${HERE}/split_negative_controls.sh"; cp "${WORK}/retrace.orig" "${HERE}/retrace_pull_library_control.sh"; cp "${WORK}/dropdraw.orig" "${HERE}/retrace_drop_draw_control.sh"; cp "${WORK}/helper.orig" "${HELPER}"; rm -rf "${WORK}"' EXIT
+WAIT_HELPER="${HERE}/wait_boundary_negative_control.py"
+trap 'cp "${WORK}/split.orig" "${HERE}/split_negative_controls.sh"; cp "${WORK}/retrace.orig" "${HERE}/retrace_pull_library_control.sh"; cp "${WORK}/dropdraw.orig" "${HERE}/retrace_drop_draw_control.sh"; cp "${WORK}/helper.orig" "${HELPER}"; cp "${WORK}/wait.orig" "${WAIT_HELPER}"; rm -rf "${WORK}"' EXIT
 
 cp "${HERE}/split_negative_controls.sh" "${WORK}/split.orig"
 cp "${HERE}/retrace_pull_library_control.sh" "${WORK}/retrace.orig"
 cp "${HERE}/retrace_drop_draw_control.sh" "${WORK}/dropdraw.orig"
 cp "${HELPER}" "${WORK}/helper.orig"
+cp "${WAIT_HELPER}" "${WORK}/wait.orig"
 
 echo "=== baseline: the smoke test must be GREEN before anything is perturbed"
 if ! bash "${HERE}/control_smoke_test.sh" > "${WORK}/before.log" 2>&1; then
@@ -31,9 +33,9 @@ tail -1 "${WORK}/before.log"
 echo
 echo "=== perturbation: remove the evidence check from both controls"
 python3 - "${HERE}/split_negative_controls.sh" "${HERE}/retrace_pull_library_control.sh" \
-        "${HERE}/retrace_drop_draw_control.sh" <<'PY' || exit 1
+        "${HERE}/retrace_drop_draw_control.sh" "${WAIT_HELPER}" <<'PY' || exit 1
 import sys
-split, retrace, dropdraw = sys.argv[1], sys.argv[2], sys.argv[3]
+split, retrace, dropdraw, wait = sys.argv[1:]
 # (file, [(needle, the prefix the line must start with)]). The draw-drop control has THREE
 # evidence checks rather than one, because "the picture went red" has three different ways of
 # being somebody else's red: the SSIM never fell, the library never said the knob armed, and the
@@ -49,16 +51,17 @@ split, retrace, dropdraw = sys.argv[1], sys.argv[2], sys.argv[3]
 # nothing was ever silently proved - but the one control it was most about was never perturbed.
 # Reproduced on p5/joint@e61d0012 before this line changed.
 #
-# AND THE SPLIT CONTROL HAS THREE EVIDENCE CHECKS, NOT ONE, so all three are reverted. E1's is a
-# read of the entry's own private library log, E3(a)'s ctest-output regex is the `elif` above,
-# and E3(a)'s private-log half is ID-65's addition. Perturbing only one of the three leaves the
+# AND THE SPLIT CONTROL HAS THREE EVIDENCE CHECKS, NOT ONE. E1 checks each boundary
+# probe's own observation and assertion; E3(a) checks its assertion and private log.
+# All three are reverted: perturbing only one leaves the
 # other two catching the smoke test's "unrelated failure" case, and the case never flips - which
 # is what this script measured the first time the perturbation actually applied.
 rules = [
     (split, [('LINE', '"${log_helper}" assertion', ('if ! ', 'elif ! ')),
-             ('SUBST', '"[A-Za-z_][A-Za-z_0-9]*"\\}\' || exit 1', '"[A-Za-z_][A-Za-z_0-9]*"\\}\' || true'),
              ('SUBST', '"${private_evidence}" "${name}" || exit 1',
                        '"${private_evidence}" "${name}" || true')]),
+    (wait, [('SUBST', 'if not own_negative(text, observation, diagnostic):',
+                       'if False:  # E1 evidence check removed by red-check')]),
     (retrace, [('LINE', 'grep -qF "${EVIDENCE}"', ('if ! ',))]),
     (dropdraw, [('LINE', 'awk -v a="${ssim}"', ('if ! ',)),
                 ('LINE', '[ -z "${armed_line}" ]', ('if ',)),
@@ -134,8 +137,9 @@ echo
 cp "${WORK}/split.orig" "${HERE}/split_negative_controls.sh"
 cp "${WORK}/retrace.orig" "${HERE}/retrace_pull_library_control.sh"
 cp "${WORK}/dropdraw.orig" "${HERE}/retrace_drop_draw_control.sh"
+cp "${WORK}/wait.orig" "${WAIT_HELPER}"
 echo "=== ID-62 perturbation: remove only the skip check"
-python3 - "${HELPER}" <<'PY' || exit 1
+python3 - "${HELPER}" "${WAIT_HELPER}" <<'PY' || exit 1
 from pathlib import Path
 import sys
 path = Path(sys.argv[1])
@@ -144,6 +148,12 @@ needle = '        if skipped:\n'
 if text.count(needle) != 1:
     raise SystemExit('expected exactly one skip check')
 path.write_text(text.replace(needle, '        if False:  # skip check removed by red-check\n'))
+path = Path(sys.argv[2])
+text = path.read_text()
+needle = '        if case.find("skipped") is not None or case.get("status") in {"notrun", "disabled"}:\n'
+if text.count(needle) != 1:
+    raise SystemExit('expected exactly one E1 skip check')
+path.write_text(text.replace(needle, '        if False:  # E1 skip check removed by red-check\n'))
 PY
 bash "${HERE}/control_smoke_test.sh" > "${WORK}/skips.log" 2>&1
 rc=$?
diff --git a/scripts/ci/split_negative_controls.sh b/scripts/ci/split_negative_controls.sh
index dd89e0f3..0b1f70a4 100644
--- a/scripts/ci/split_negative_controls.sh
+++ b/scripts/ci/split_negative_controls.sh
@@ -33,8 +33,10 @@
 # CONTROL", "is the E3(a) NEGATIVE CONTROL"), and it is tempting to grep for that. It is not
 # evidence: it is written at config load, by every process in the run, whatever happens next. A
 # setup abort would carry it too. It proves the knob was READ, never that the knob caused the red.
-# Only the failing case's own diagnostic does that. ID-53 gives each Split entry a private
-# library log: E1 reads its Fatal there; E3(a) reads the scenario assertion in ctest output.
+# Only the failing case's own diagnostic does that. E1 now observes deterministic transport
+# waits in dedicated CPU tests; E3(a) retains its scenario assertion and private library log.
+# P5e ID-122: ordinary run-ahead draws need not fail with VERB_BARRIER=0, and the old
+# overlap Fatal cannot fire with the default BATCH_WAITS=1. Pixel failures are not E1 evidence.
 #
 # Usage:  split_negative_controls.sh [--self-test]
 #   CTEST          ctest binary                       (default: ctest)
@@ -139,20 +141,14 @@ run_control() {
   cat "${out}"
 
   # Inspect JUnit before exit status or private Fatal: a skipped pre-flight can carry both.
-  label='E3(a)'
-  [ "${evidence}" != private-barrier-fatal ] || label=E1
-  python3 "${log_helper}" results "${manifest}" "${filter}" "${result}" "${label}" || exit 1
+  python3 "${log_helper}" results "${manifest}" "${filter}" "${result}" 'E3(a)' || exit 1
 
   if [ "${control_rc}" -eq 0 ]; then
     echo "::error::${name} left ${matched} split entries GREEN, so the knob it turns is not load-bearing and the gate it controls proves nothing."
     exit 1
   fi
 
-  # E1's MGLOG_F sink is the private file, never ctest's status or transcript.
-  if [ "${evidence}" = "private-barrier-fatal" ]; then
-    python3 "${log_helper}" evidence "${manifest}" "${filter}" \
-      'Fatal\{BarrierViolation, "[A-Za-z_][A-Za-z_0-9]*"\}' || exit 1
-  elif ! python3 "${log_helper}" assertion "${manifest}" "${filter}" "${result}" "${evidence}"; then
+  if ! python3 "${log_helper}" assertion "${manifest}" "${filter}" "${result}" "${evidence}"; then
     echo "::error::${name} FAILED: red lacks its persistent-map push diagnostic. Required: ${evidence}"
     exit 1
   fi
@@ -168,26 +164,15 @@ run_control() {
   echo "${name} turned ${matched} selected entries red, and the red carries the scenario's own diagnostic, as it must"
 }
 
-# E1: c1 ClientSession::EmitAndWait emits MGLOG_F Fatal{BarrierViolation, "<slot>"}.
-# This asserts an observed overlap with the applier, which is timing-dependent.
-# Without that Fatal in a fresh selected file E1 fails; pixel/status fallbacks do not count.
-# Keep the ID-53-approved SmallRing selection as well as the default lane.
-# ...MINUS TheServerStampedAVerbBoundaryOnThisDrawingFrame, and that exclusion is load-bearing
-# rather than tidying (P5e, ID-122). That case is package gl's ID-115 POSITIVE CONTROL: it reads
-# a PipeStats window out of the lane's own private log, so it runs ONLY in the strict-arming
-# lane and skips everywhere else BY DESIGN, whatever this knob is set to. E1's selection began
-# matching it the moment gl added it, and ID-62 makes a SKIPPED SELECTED entry a hard failure -
-# correctly, because a control that silently loses its subjects proves nothing. E1 then reported
-# "the knob killed the pre-flight, not the entry" while the knob was in fact working: four other
-# selected entries went red with the abort in the same run. So the bug was in WHO E1 selects,
-# not in what it asserts, and the fix excludes a case that can never run here rather than
-# teaching E1 to tolerate skips - which would have thrown ID-62 away.
-run_control "negative control E1 (MOBILEGL_IPC_VERB_BARRIER=0)" \
-  'DirectGLES\.Split\.(SmallRing\.)?(Triangle|ClearThenReadPixels)' \
-  'private-barrier-fatal' \
-  '' \
-  'TheServerStampedAVerbBoundaryOnThisDrawingFrame' \
-  MOBILEGL_IPC_VERB_BARRIER=0
+# E1: the default arm must actually park for a kWaitApplied record and for a
+# kWaitNone record whose server has no run-ahead cap. Removing the verb barrier
+# must fail those exact return-before-apply assertions. A third positive case
+# proves that a cap-authorized kWaitNone record does not wait. The peer releases
+# on an observed Park or on the client's return, not on a sleep or pixel race.
+# The helper demands green baseline, two named reds, and green restoration;
+# skipped/missing cases, timeouts and unrelated failures never count as evidence.
+python3 "$(dirname "$0")/wait_boundary_negative_control.py" \
+  --ctest "${CTEST}" --out "${CONTROL_TMPDIR}/e1" || exit 1
 
 # E3(a): PersistentMapTracker::PushBlocksFor stops at blockBytes == 0 - deliberately, because 0
 # is the negative control and not "unlimited". Two independent halves are now required:
diff --git a/scripts/ci/testdata/split_private_log_smoke.sh b/scripts/ci/testdata/split_private_log_smoke.sh
index 86fa8983..ad68ae5f 100644
--- a/scripts/ci/testdata/split_private_log_smoke.sh
+++ b/scripts/ci/testdata/split_private_log_smoke.sh
@@ -1,5 +1,5 @@
 #!/bin/bash
-# Exercise the production control, including the private-file read (ID-53 / R-16).
+# Exercise E1's per-test boundary evidence and E3(a)'s private-file read (R-16).
 set -euo pipefail
 HERE="$(cd "$(dirname "$0")/.." && pwd)"
 WORK=$(mktemp -d "${TMPDIR:-/tmp}/split-private-log.XXXXXX")
@@ -14,25 +14,21 @@ for mode in missing-fatal stdout-fatal stale-fatal evidence e3-unrelated e3-no-p
     bash "${HERE}/split_negative_controls.sh" > "${WORK}/${mode}.out" 2>&1 || rc=$?
   if [ "${mode}" = evidence ]; then
     [ "${rc}" = 0 ] && grep -q "negative control E3(a).*scenario's own diagnostic" "${WORK}/${mode}.out" || {
-      cat "${WORK}/${mode}.out"; echo "NOT OK private-file Fatal must PASS"; exit 1;
+      cat "${WORK}/${mode}.out"; echo "NOT OK own boundary/private-file evidence must PASS"; exit 1;
     }
-    grep -qFx "private-log evidence: DirectGLES.Split.ClearThenReadPixelsScenario.ClearWithNoDrawIsVisibleToDefaultFramebufferReadPixels: ${WORK}/${mode}/entry.log" "${WORK}/${mode}.out" || {
+    grep -qFx "private-log evidence: DirectGLES.Split.PersistentCoherentMapScenario.TwoWritesThroughTheCoherentPointerEachReachTheirOwnDraw: ${WORK}/${mode}/pmap.log" "${WORK}/${mode}.out" || {
       cat "${WORK}/${mode}.out"; echo "NOT OK private-file evidence line must name the selected entry and path"; exit 1;
     }
   else
-    message='E1 FAILED: selected private logs lack expected Fatal'
+    message='red lacks its own observed wait-boundary failure'
     [ "${mode}" != e3-unrelated ] || message='FAILED: red lacks its persistent-map push diagnostic'
     case "${mode}" in
       e3-no-private) message='no selected private log carries /MGPipe: persistent-map push disabled' ;;
-      skipped-selection) message='SplitLogPaths FAILED: E1 control: the knob killed the pre-flight, not the entry - 1 selected entries skipped' ;;
+      skipped-selection|notrun-selection) message='selected testcase skipped or did not run' ;;
       e3-skipped-selection) message='SplitLogPaths FAILED: E3(a) control: the knob killed the pre-flight, not the entry - 1 selected entries skipped' ;;
-      notrun-selection|missing-selection) message='SplitLogPaths FAILED: E1 control: 1 selected entries did not run' ;;
+      missing-selection) message='selected testcase names are missing, duplicated or unexpected' ;;
     esac
-    if [[ "${mode}" = *-selection ]]; then
-      match=(-qFx)
-    else
-      match=(-qF)
-    fi
+    match=(-qF)
     [ "${rc}" != 0 ] && grep "${match[@]}" "${message}" "${WORK}/${mode}.out" || {
       cat "${WORK}/${mode}.out"; echo "NOT OK ${mode}: control must report FAILED for its own reason"; exit 1;
     }
diff --git a/scripts/ci/testdata/stub_ctest.sh b/scripts/ci/testdata/stub_ctest.sh
index d98efdc6..eb6055e7 100755
--- a/scripts/ci/testdata/stub_ctest.sh
+++ b/scripts/ci/testdata/stub_ctest.sh
@@ -52,10 +52,80 @@ for a in "$@"; do
   [ "$a" = "--show-only=json-v1" ] && json_requested=1
   [ "$a" = "-N" ] && listing_requested=1
   if [ "$prev" = "--output-junit" ]; then junit="$a"; fi
+  if [ "$prev" = "-R" ]; then selector="$a"; fi
   prev="$a"
 done
 listing_requested="${listing_requested:-0}"
 
+# E1's CPU-only boundary probes use their own testcase results. Keep observations
+# inside each testcase so stdout-only and stale evidence remain rejected.
+if [[ "${selector:-}" == *RemoteWaitBoundaryControl* ]]; then
+  python3 - "${mode}" "${junit}" "${selector}" <<'PY'
+import os, re, sys
+import xml.etree.ElementTree as ET
+mode, path, selector = sys.argv[1:]
+barrier = int(os.environ['MOBILEGL_IPC_VERB_BARRIER'])
+negative = barrier == 0
+prefix = 'RemoteWaitBoundaryControl.'
+specs = [
+ ('AppliedClassWaitsWithRunAheadCap', 'GenerateMipmap', 1, True,
+  'E1 wait boundary: GenerateMipmap returned before apply'),
+ ('MissingServerCapKeepsClearLockstep', 'Clear', 0, True,
+  'E1 wait boundary: Clear without server cap returned before apply'),
+ ('ServerCapAllowsClearToRunAhead', 'Clear', 1, False, ''),
+]
+root = ET.Element('testsuite')
+failures = 0
+for index, (short, op, cap, waits, diagnostic) in enumerate(specs):
+    name = prefix + short
+    if not re.search(selector, name):
+        continue
+    if mode == 'e1-empty' or (negative and mode == 'missing-selection' and index == 1):
+        continue
+    case = ET.SubElement(root, 'testcase', name=name, status='run')
+    waited = int(waits and barrier == 1)
+    observation = (f'E1 observation: op={op} cap={cap} barrier={barrier} parked={waited} '
+                   f'applied_before_return={waited} emitted=1 peer_seen=1')
+    failed = negative and mode != 'green'
+    if mode == 'e1-red-baseline' and 'baseline' in path:
+        failed = True
+    if mode == 'e1-restore-red' and 'restored' in path:
+        failed = True
+    if mode == 'e1-waitall' and not waits:
+        failed = True
+        observation = observation.replace('parked=0', 'parked=1').replace('applied_before_return=0', 'applied_before_return=1')
+    if negative and mode == 'skipped-selection':
+        ET.SubElement(case, 'skipped')
+        failed = False
+    if negative and mode == 'notrun-selection':
+        case.set('status', 'notrun')
+        failed = False
+    if failed:
+        ET.SubElement(case, 'failure', message='control red')
+        failures += 1
+    text = observation + '\n' + (diagnostic if negative else '')
+    if negative:
+        if mode == 'unrelated' or mode == 'wrong-fatal':
+            text = observation + '\nUNRELATED_CONTROL_FAILURE'
+        elif mode == 'missing-fatal' or (mode == 'partial-fatal' and index == 1):
+            text = diagnostic
+        elif mode == 'stdout-fatal':
+            print(text)  # Must not qualify as this testcase's own evidence.
+            text = 'UNRELATED_CONTROL_FAILURE'
+        elif mode == 'stale-fatal':
+            text = text.replace('barrier=0', 'barrier=1')
+        elif mode == 'e1-no-peer':
+            text = text.replace('peer_seen=1', 'peer_seen=0')
+        elif mode == 'e1-no-emit':
+            text = text.replace('emitted=1', 'emitted=0')
+    ET.SubElement(case, 'system-out').text = text
+ET.ElementTree(root).write(path, encoding='utf-8', xml_declaration=True)
+print(f'E1 stub: {len(root)} selected, {failures} failed')
+sys.exit(8 if failures else 0)
+PY
+  exit $?
+fi
+
 emit_listing() {
   echo "Test project /stub"
   if [ "${mode}" = "retrace-noselect" ] || [ "${mode}" = "dropdraw-noselect" ]; then
diff --git a/scripts/ci/wait_boundary_negative_control.py b/scripts/ci/wait_boundary_negative_control.py
new file mode 100644
index 00000000..0b4e4fd4
--- /dev/null
+++ b/scripts/ci/wait_boundary_negative_control.py
@@ -0,0 +1,97 @@
+#!/usr/bin/env python3
+"""E1: green/red/restored-green proof of real ClientSession wait boundaries.
+
+The peer holds apply until the actual transport parks or the emit call returns.
+VERB_BARRIER=0 must fail only the two owed waits; ordinary run-ahead draws need
+not fail. Each arm is checked from its own CTest JUnit testcase, never a global
+grep, stale library log, arbitrary nonzero exit, or timing-dependent pixel.
+"""
+import argparse
+import os
+from pathlib import Path
+import re
+import subprocess
+import sys
+import xml.etree.ElementTree as ET
+
+PREFIX = "RemoteWaitBoundaryControl."
+CASES = {
+    "AppliedClassWaitsWithRunAheadCap": ("GenerateMipmap", 1, True,
+        "E1 wait boundary: GenerateMipmap returned before apply"),
+    "MissingServerCapKeepsClearLockstep": ("Clear", 0, True,
+        "E1 wait boundary: Clear without server cap returned before apply"),
+    "ServerCapAllowsClearToRunAhead": ("Clear", 1, False, ""),
+}
+
+
+def own_negative(text, expected_observation, diagnostic):
+    return expected_observation in text and diagnostic in text
+
+
+def inspect(path, selected, barrier, negative, rc):
+    root = ET.parse(path).getroot()
+    cases = root.findall(".//testcase")
+    names = [case.get("name") for case in cases]
+    if len(names) != len(set(names)) or set(names) != set(selected):
+        raise ValueError("selected testcase names are missing, duplicated or unexpected")
+    for case in cases:
+        name = case.get("name")
+        if case.find("skipped") is not None or case.get("status") in {"notrun", "disabled"}:
+            raise ValueError(f"{name}: selected testcase skipped or did not run")
+        failed = case.find("failure") is not None or case.find("error") is not None
+        op, cap, waits, diagnostic = CASES[name.removeprefix(PREFIX)]
+        waited = int(waits and barrier == 1)
+        observation = (f"E1 observation: op={op} cap={cap} barrier={barrier} parked={waited} "
+                       f"applied_before_return={waited} emitted=1 peer_seen=1")
+        text = "\n".join(case.itertext())
+        if negative:
+            if not failed or rc == 0:
+                raise ValueError(f"{name}: disabled barrier did not fail the owed wait")
+            if not own_negative(text, observation, diagnostic):
+                raise ValueError(f"{name}: red lacks its own observed wait-boundary failure")
+        elif failed or rc != 0 or observation not in text:
+            raise ValueError(f"{name}: baseline/restored arm did not execute its green boundary proof")
+
+
+def main():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--ctest", default=os.environ.get("CTEST", "ctest"))
+    parser.add_argument("--out", type=Path, required=True)
+    args = parser.parse_args()
+    args.out.mkdir(parents=True, exist_ok=True)
+    all_cases = [PREFIX + name for name in CASES]
+    negative_cases = [PREFIX + name for name, (_, _, waits, _) in CASES.items() if waits]
+    ok = True
+    for arm, barrier, negative, selected in (
+        ("baseline", 1, False, all_cases),
+        ("control", 0, True, negative_cases),
+        ("restored", 1, False, all_cases),
+    ):
+        # Never run a negative arm against a failed baseline. A failed negative
+        # still proceeds through restoration and must not consume stale XML.
+        if arm == "control" and not ok:
+            continue
+        result = args.out / f"e1-{arm}.xml"
+        result.unlink(missing_ok=True)
+        env = os.environ.copy()
+        env["MOBILEGL_IPC_VERB_BARRIER"] = str(barrier)
+        selector = "^(" + "|".join(re.escape(name) for name in selected) + ")$"
+        command = [args.ctest, "-L", "unit", "-R", selector, "--no-tests=error",
+                   "--output-on-failure", "--output-junit", str(result)]
+        try:
+            run = subprocess.run(command, env=env, stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
+                                 text=True, timeout=90)
+            (args.out / f"e1-{arm}.out").write_text(run.stdout, encoding="utf-8")
+            print(run.stdout, end="", flush=True)
+            inspect(result, selected, barrier, negative, run.returncode)
+            print(f"E1 {arm}: {'EXPECTED_RED' if negative else 'GREEN'} ({len(selected)} cases)", flush=True)
+        except (OSError, ValueError, ET.ParseError, subprocess.TimeoutExpired) as exc:
+            print(f"E1 FAILED: {arm}: {exc}", file=sys.stderr, flush=True)
+            ok = False
+    if ok:
+        print("negative control E1: owed waits failed by their own observed boundary assertions; baseline and restoration green")
+    return 0 if ok else 1
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())