diff --git a/src/deepiri_modelkit/streaming/__init__.py b/src/deepiri_modelkit/streaming/__init__.py
index b498d7b..f6beb86 100644
--- a/src/deepiri_modelkit/streaming/__init__.py
+++ b/src/deepiri_modelkit/streaming/__init__.py
@@ -1,6 +1,13 @@
 """Streaming client and utilities"""
 
 from .event_stream import StreamingClient
+from .sidecar_utils import env_float, resolve_grpc_addr, sidecar_payload_from_fields
 from .topics import StreamTopics
 
-__all__ = ["StreamingClient", "StreamTopics"]
+__all__ = [
+    "StreamingClient",
+    "StreamTopics",
+    "env_float",
+    "resolve_grpc_addr",
+    "sidecar_payload_from_fields",
+]
diff --git a/src/deepiri_modelkit/streaming/sidecar_utils.py b/src/deepiri_modelkit/streaming/sidecar_utils.py
new file mode 100644
index 0000000..3af5322
--- /dev/null
+++ b/src/deepiri_modelkit/streaming/sidecar_utils.py
@@ -0,0 +1,79 @@
+"""
+Shared Sugar Glider/Synapse sidecar helpers.
+
+These utilities are reused by multiple services (for example Cyrex and Helox)
+to keep sidecar transport behavior consistent across repos.
+"""
+
+from __future__ import annotations
+
+import json
+import os
+from typing import Any, Callable, Dict, Optional
+from urllib.parse import urlparse
+
+
+def env_float(name: str, default: float, logger: Optional[Callable[[str], None]] = None) -> float:
+    """Read a float env var with safe fallback."""
+    raw = os.getenv(name)
+    if raw is None:
+        return default
+    try:
+        return float(raw)
+    except ValueError:
+        if logger is not None:
+            logger(f"invalid float env {name}={raw!r}; using {default}")
+        return default
+
+
+def resolve_grpc_addr(base_url: str, explicit_grpc_addr: Optional[str] = None) -> str:
+    """
+    Resolve sidecar gRPC host:port from explicit/env/base URL.
+
+    Resolution order:
+    1) explicit_grpc_addr
+    2) SYNAPSE_GRPC_ADDR
+    3) derive from base_url (8081 -> 50051)
+    """
+    env_addr = os.getenv("SYNAPSE_GRPC_ADDR")
+    if explicit_grpc_addr:
+        return explicit_grpc_addr
+    if env_addr:
+        return env_addr
+
+    parsed = urlparse(base_url)
+    if parsed.scheme in {"http", "https"}:
+        host = parsed.hostname or "localhost"
+        port = parsed.port
+        if port is None:
+            port = 443 if parsed.scheme == "https" else 80
+        if port == 8081:
+            port = 50051
+        return f"{host}:{port}"
+
+    if base_url:
+        return base_url
+    return "localhost:50051"
+
+
+def sidecar_payload_from_fields(fields: Dict[str, Any]) -> Dict[str, Any]:
+    """Normalize sidecar event fields to a payload dict."""
+    payload = fields.get("payload", {})
+    if isinstance(payload, str):
+        try:
+            payload = json.loads(payload)
+        except ValueError:
+            payload = {}
+    elif not isinstance(payload, dict):
+        payload = {}
+
+    if "event" not in payload and fields.get("event_type"):
+        payload["event"] = fields.get("event_type")
+
+    if "timestamp" not in payload and fields.get("timestamp"):
+        payload["timestamp"] = fields.get("timestamp")
+
+    if "sender" not in payload and fields.get("sender"):
+        payload["sender"] = fields.get("sender")
+
+    return payload