feat(streaming): wire streaming path through orchestrator task pipeline

- _stream_agent_response_to_redis() publishes chunk/done messages to Redis pub-sub
- _process_message() uses streaming path for web channel with no tools registered
- Non-web channels (Slack, WhatsApp) and tool-enabled agents use non-streaming run_agent()
- streaming_delivered flag prevents double-publish when streaming path is active
- _send_response() web branch changed from 'response' to 'done' message type for consistency

packages/orchestrator/orchestrator/tasks.py

@@ -66,7 +66,7 @@ import redis.asyncio as aioredis
 
 from gateway.channels.whatsapp import send_whatsapp_message
 from orchestrator.agents.builder import build_messages_with_memory
-from orchestrator.agents.runner import run_agent
+from orchestrator.agents.runner import run_agent, run_agent_streaming
 from orchestrator.audit.logger import AuditLogger
 from orchestrator.escalation.handler import check_escalation_rules, escalate_to_human
 from orchestrator.main import app
@@ -526,8 +526,32 @@ async def _process_message(
     tool_registry = get_tools_for_agent(agent)
 
     # -------------------------------------------------------------------------
-    # Run agent with tool loop
+    # Run agent — streaming for web channel (no tools), non-streaming otherwise
     # -------------------------------------------------------------------------
+    is_web_channel = str(msg.channel) == "web"
+    has_tools = bool(tool_registry)
+
+    # Track whether the streaming path already published to Redis so we can
+    # skip the _send_response() call below (avoids a duplicate publish).
+    streaming_delivered = False
+
+    if is_web_channel and not has_tools:
+        # Streaming path: yield tokens directly to Redis pub-sub so the
+        # WebSocket handler can forward them to the browser immediately.
+        # The tool-call loop is skipped because there are no tools registered.
+        web_conversation_id: str = extras.get("conversation_id", "") or ""
+        web_tenant_id: str = extras.get("tenant_id", "") or str(msg.tenant_id or "")
+        response_text = await _stream_agent_response_to_redis(
+            msg=msg,
+            agent=agent,
+            messages=enriched_messages,
+            conversation_id=web_conversation_id,
+            tenant_id=web_tenant_id,
+        )
+        streaming_delivered = True
+    else:
+        # Non-streaming path: tool-call loop + full response (Slack, WhatsApp,
+        # and web channel when tools are registered).
         response_text = await run_agent(
             msg,
             agent,
@@ -592,7 +616,11 @@ async def _process_message(
         len(relevant_context),
     )
 
-    # Send response via channel-aware routing
+    # Send response via channel-aware routing.
+    # Skip for the streaming path — _stream_agent_response_to_redis already
+    # published chunk + done messages to Redis; calling _send_response here
+    # would publish a duplicate done message.
+    if not streaming_delivered:
         await _send_response(msg.channel, response_text, response_extras)
 
     # -------------------------------------------------------------------------
@@ -733,6 +761,87 @@ def _extract_tool_name_from_confirmation(confirmation_message: str) -> str:
     return "unknown_tool"
 
 
+# Fallback text for streaming errors (mirrors runner._FALLBACK_RESPONSE)
+_FALLBACK_RESPONSE_TEXT = (
+    "I'm having trouble processing your request right now. "
+    "Please try again in a moment."
+)
+
+
+async def _stream_agent_response_to_redis(
+    msg: "KonstructMessage",
+    agent: Any,
+    messages: list[dict],
+    conversation_id: str,
+    tenant_id: str,
+) -> str:
+    """
+    Stream LLM token chunks to Redis pub-sub for web channel delivery.
+
+    Calls run_agent_streaming() and publishes each token as a
+    ``{"type": "chunk", "text": "<token>"}`` message to the webchat response
+    channel. Publishes a final ``{"type": "done", "text": "<full_response>"}``
+    when the stream completes.
+
+    The WebSocket handler (web.py) listens on this channel and forwards
+    chunk/done messages directly to the browser, enabling word-by-word display.
+
+    Args:
+        msg:             The inbound KonstructMessage.
+        agent:           The ORM Agent instance.
+        messages:        Memory-enriched messages array.
+        conversation_id: Web conversation UUID string.
+        tenant_id:       Konstruct tenant UUID string.
+
+    Returns:
+        The full assembled response text (for memory persistence and audit).
+    """
+    response_channel = webchat_response_key(tenant_id, conversation_id)
+    chunks: list[str] = []
+    full_response = _FALLBACK_RESPONSE_TEXT
+
+    publish_redis = aioredis.from_url(settings.redis_url)
+    try:
+        async for token in run_agent_streaming(msg, agent, messages=messages):
+            chunks.append(token)
+            await publish_redis.publish(
+                response_channel,
+                json.dumps({"type": "chunk", "text": token}),
+            )
+
+        full_response = "".join(chunks) or _FALLBACK_RESPONSE_TEXT
+        await publish_redis.publish(
+            response_channel,
+            json.dumps({
+                "type": "done",
+                "text": full_response,
+                "conversation_id": conversation_id,
+            }),
+        )
+    except Exception:
+        logger.exception(
+            "Streaming agent response failed for conversation=%s tenant=%s",
+            conversation_id,
+            tenant_id,
+        )
+        # Publish a done marker with fallback so the browser doesn't hang
+        try:
+            await publish_redis.publish(
+                response_channel,
+                json.dumps({
+                    "type": "done",
+                    "text": full_response,
+                    "conversation_id": conversation_id,
+                }),
+            )
+        except Exception:
+            pass
+    finally:
+        await publish_redis.aclose()
+
+    return full_response
+
+
 async def _send_response(
     channel: Any,
     text: str,
@@ -792,7 +901,9 @@ async def _send_response(
         )
 
     elif channel_str == "web":
-        # Publish agent response to Redis pub-sub so the WebSocket handler can deliver it
+        # Publish agent response to Redis pub-sub so the WebSocket handler can deliver it.
+        # Uses "done" type (consistent with streaming path) so the WebSocket handler
+        # processes it identically whether or not streaming was used.
         web_conversation_id: str = extras.get("conversation_id", "") or ""
         web_tenant_id: str = extras.get("tenant_id", "") or ""
 
@@ -808,7 +919,7 @@ async def _send_response(
             await publish_redis.publish(
                 response_channel,
                 json.dumps({
-                    "type": "response",
+                    "type": "done",
                     "text": text,
                     "conversation_id": web_conversation_id,
                 }),