feat: ship streaming disabled by default — opt-in via config

Streaming is now off by default for both CLI and gateway. Users opt in:

CLI (config.yaml):
  display:
    streaming: true

Gateway (config.yaml):
  streaming:
    enabled: true

This lets early adopters test streaming while existing users see zero
change. Once we have enough field validation, we flip the default to
true in a subsequent release.

cli.py

@@ -1017,6 +1017,9 @@ class HermesCLI:
         self.show_reasoning = CLI_CONFIG["display"].get("show_reasoning", False)
         self.verbose = verbose if verbose is not None else (self.tool_progress_mode == "verbose")
         
+        # streaming: stream tokens to the terminal as they arrive (display.streaming in config.yaml)
+        self.streaming_enabled = CLI_CONFIG["display"].get("streaming", False)
+
         # Streaming display state
         self._stream_buf = ""        # Partial line buffer for line-buffered rendering
         self._stream_started = False  # True once first delta arrives
@@ -1719,7 +1722,7 @@ class HermesCLI:
                 checkpoint_max_snapshots=self.checkpoint_max_snapshots,
                 pass_session_id=self.pass_session_id,
                 tool_progress_callback=self._on_tool_progress,
-                stream_delta_callback=self._stream_delta,
+                stream_delta_callback=self._stream_delta if self.streaming_enabled else None,
             )
             # Apply any pending title now that the session exists in the DB
             if self._pending_title and self._session_db:

gateway/config.py

@@ -149,7 +149,7 @@ class PlatformConfig:
 @dataclass
 class StreamingConfig:
     """Configuration for real-time token streaming to messaging platforms."""
-    enabled: bool = True
+    enabled: bool = False
     transport: str = "edit"       # "edit" (progressive editMessageText) or "off"
     edit_interval: float = 0.3    # Seconds between message edits
     buffer_threshold: int = 40    # Chars before forcing an edit
@@ -169,7 +169,7 @@ class StreamingConfig:
         if not data:
             return cls()
         return cls(
-            enabled=data.get("enabled", True),
+            enabled=data.get("enabled", False),
             transport=data.get("transport", "edit"),
             edit_interval=float(data.get("edit_interval", 0.3)),
             buffer_threshold=int(data.get("buffer_threshold", 40)),

hermes_cli/config.py

@@ -202,6 +202,7 @@ DEFAULT_CONFIG = {
         "resume_display": "full",
         "bell_on_complete": False,
         "show_reasoning": False,
+        "streaming": False,
         "skin": "default",
     },