fix(photon): use GUID for liveness probe message id

(cherry picked from commit cdb6ccadb045e599db795823a100ae7b61d377ec)

plugins/platforms/photon/sidecar/index.mjs

@@ -69,6 +69,7 @@ import { patchSpectrumTs } from "./patch-spectrum-mixed-attachments.mjs";
 import { chooseSendFormat } from "./send-format.mjs";
 import {
   classifyProbeRejection,
+  createProbeMessageId,
   shouldProbe,
   isZombieSuspect,
 } from "./stream-staleness.mjs";
@@ -267,7 +268,7 @@ console.log = (...args) => {
 // half-open ("zombie") one. `space.get` is purely local in shared/dedicated
 // mode (no chat is created or messaged); only the message read hits the wire.
 const PROBE_SPACE_ID = process.env.PHOTON_PROBE_SPACE_ID || "any;-;+10000000000";
-const PROBE_MSG_PREFIX = "hermes-liveness-probe-";
+
 
 if (!projectId || !projectSecret || !sharedToken) {
   console.error(
@@ -730,8 +731,7 @@ async function probeUpstream() {
   if (typeof app?.stop !== "function") {
     return { alive: false, hung: false, reason: "spectrum app not constructed" };
   }
-  const probeId =
-    PROBE_MSG_PREFIX + Date.now() + "-" + Math.random().toString(36).slice(2);
+  const probeId = createProbeMessageId();
   let timer = null;
   const timeout = new Promise((resolve) => {
     timer = setTimeout(

plugins/platforms/photon/sidecar/stream-staleness.mjs

@@ -23,9 +23,15 @@
 // These helpers are pure (no SDK, no timers) so tests can execute them under
 // node — see tests/plugins/platforms/photon/test_zombie_stream_watchdog.py.
 
+import { randomUUID } from "node:crypto";
+
 // gRPC NOT_FOUND is code 5; SDKs also surface it as "not found" / "NotFound"
 // message text. Anything not clearly not-found is inconclusive.
 const NOT_FOUND_RE = /not[\s_-]?found/i;
+/** Return a unique message id accepted by Spectrum's message-id parser. */
+export function createProbeMessageId() {
+  return randomUUID();
+}
 
 /**
  * Classify the rejection of the synthetic-id probe read.

tests/plugins/platforms/photon/test_zombie_stream_watchdog.py

@@ -25,12 +25,14 @@ from __future__ import annotations
 
 import asyncio
 import json
+import re
 import subprocess
 from pathlib import Path
 from typing import Any, Dict
 
 import pytest
 
+
 from gateway.config import PlatformConfig
 from plugins.platforms.photon.adapter import PhotonAdapter
 
@@ -48,7 +50,8 @@ def _make_adapter(monkeypatch: pytest.MonkeyPatch) -> PhotonAdapter:
 
 def _run_staleness_harness(script: str) -> Dict[str, Any]:
     harness = (
-        "import { classifyProbeRejection, shouldProbe, isZombieSuspect } "
+        "import { classifyProbeRejection, shouldProbe, isZombieSuspect, "
+        "createProbeMessageId } "
         f"from {json.dumps(_MODULE.as_uri())};\n"
         + script
     )
@@ -63,6 +66,20 @@ def _run_staleness_harness(script: str) -> Dict[str, Any]:
     return json.loads(run.stdout)
 
 
+def test_probe_message_id_is_guid_shaped_and_unique() -> None:
+    out = _run_staleness_harness(
+        """
+        const first = createProbeMessageId();
+        const second = createProbeMessageId();
+        process.stdout.write(JSON.stringify({ first, second }));
+        """
+    )
+    guid_re = r"^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$"
+    assert re.fullmatch(guid_re, out["first"])
+    assert re.fullmatch(guid_re, out["second"])
+    assert out["first"] != out["second"]
+
+
 def test_probe_rejection_classification_is_strict() -> None:
     """Only not-found-shaped rejections prove liveness; everything else is
     inconclusive — a rejected probe is NEVER treated as alive (#45580's