refactor(bus): type outbound runtime events

nanobot/agent/loop.py

@@ -31,6 +31,13 @@ from nanobot.agent.tools.message import MessageTool
 from nanobot.agent.tools.registry import ToolRegistry
 from nanobot.agent.tools.self import MyTool
 from nanobot.bus.events import InboundMessage, OutboundMessage
+from nanobot.bus.outbound_events import (
+    RetryWaitEvent,
+    StreamDeltaEvent,
+    StreamedResponseEvent,
+    StreamEndEvent,
+    outbound_message_for_event,
+)
 from nanobot.bus.progress import build_bus_progress_callback
 from nanobot.bus.queue import MessageBus
 from nanobot.bus.runtime_events import (
@@ -567,14 +574,12 @@ class AgentLoop:
         """Build a retry-wait callback that publishes to the message bus."""
 
         async def _on_retry_wait(content: str) -> None:
-            meta = dict(msg.metadata or {})
-            meta["_retry_wait"] = True
             await self.bus.publish_outbound(
-                OutboundMessage(
+                outbound_message_for_event(
                     channel=msg.channel,
                     chat_id=msg.chat_id,
-                    content=content,
-                    metadata=meta,
+                    event=RetryWaitEvent(content=content),
+                    metadata=msg.metadata,
                 )
             )
 
@@ -999,26 +1004,31 @@ class AgentLoop:
                             return f"{stream_base_id}:{stream_segment}"
 
                         async def on_stream(delta: str) -> None:
-                            meta = dict(msg.metadata or {})
-                            meta["_stream_delta"] = True
-                            meta["_stream_id"] = _current_stream_id()
-                            await self.bus.publish_outbound(OutboundMessage(
-                                channel=msg.channel, chat_id=msg.chat_id,
-                                content=delta,
-                                metadata=meta,
-                            ))
+                            await self.bus.publish_outbound(
+                                outbound_message_for_event(
+                                    channel=msg.channel,
+                                    chat_id=msg.chat_id,
+                                    event=StreamDeltaEvent(
+                                        content=delta,
+                                        stream_id=_current_stream_id(),
+                                    ),
+                                    metadata=msg.metadata,
+                                )
+                            )
 
                         async def on_stream_end(*, resuming: bool = False) -> None:
                             nonlocal stream_segment
-                            meta = dict(msg.metadata or {})
-                            meta["_stream_end"] = True
-                            meta["_resuming"] = resuming
-                            meta["_stream_id"] = _current_stream_id()
-                            await self.bus.publish_outbound(OutboundMessage(
-                                channel=msg.channel, chat_id=msg.chat_id,
-                                content="",
-                                metadata=meta,
-                            ))
+                            await self.bus.publish_outbound(
+                                outbound_message_for_event(
+                                    channel=msg.channel,
+                                    chat_id=msg.chat_id,
+                                    event=StreamEndEvent(
+                                        stream_id=_current_stream_id(),
+                                        resuming=resuming,
+                                    ),
+                                    metadata=msg.metadata,
+                                )
+                            )
                             stream_segment += 1
 
                     response = await self._process_message(
@@ -1371,9 +1381,10 @@ class AgentLoop:
         preview = final_content[:120] + "..." if len(final_content) > 120 else final_content
         logger.info("Response to {}:{}: {}", msg.channel, msg.sender_id, preview)
 
+        event = None
         meta = dict(msg.metadata or {})
         if on_stream is not None and stop_reason not in {"error", "tool_error"}:
-            meta["_streamed"] = True
+            event = StreamedResponseEvent()
         if turn_latency_ms is not None:
             meta["latency_ms"] = int(turn_latency_ms)
 
@@ -1381,6 +1392,7 @@ class AgentLoop:
             channel=msg.channel,
             chat_id=msg.chat_id,
             content=final_content,
+            event=event,
             metadata=meta,
         )
 

nanobot/bus/events.py

@@ -2,7 +2,10 @@
 
 from dataclasses import dataclass, field
 from datetime import datetime
-from typing import Any
+from typing import TYPE_CHECKING, Any
+
+if TYPE_CHECKING:
+    from nanobot.bus.outbound_events import OutboundEvent
 
 # Optional ``OutboundMessage.metadata`` key for structured, channel-agnostic UI
 # payloads. Value is JSON-serializable with at least ``kind``; rich clients may
@@ -39,9 +42,9 @@ class InboundMessage:
 class OutboundMessage:
     """Message to send to a chat channel.
 
-    ``metadata`` can carry routing (``message_id``, …), trace flags (``_progress``),
-    and optional ``OUTBOUND_META_AGENT_UI`` blobs for rich clients; non-WebUI
-    channels may ignore unknown keys.
+    ``event`` carries internal runtime/UI semantics. ``metadata`` is reserved
+    for channel routing context (``message_id``, thread ids, etc.) and optional
+    ``OUTBOUND_META_AGENT_UI`` blobs for rich clients.
     """
 
     channel: str
@@ -51,3 +54,4 @@ class OutboundMessage:
     media: list[str] = field(default_factory=list)
     metadata: dict[str, Any] = field(default_factory=dict)
     buttons: list[list[str]] = field(default_factory=list)
+    event: "OutboundEvent | None" = None

nanobot/bus/outbound_events.py

@@ -0,0 +1,127 @@
+"""Typed outbound events carried by :class:`OutboundMessage`.
+
+The message bus still transports :class:`nanobot.bus.events.OutboundMessage`
+because channels need chat routing fields. Runtime/UI semantics live on the
+message's explicit ``event`` field rather than in reserved metadata flags.
+"""
+
+from __future__ import annotations
+
+from collections.abc import Mapping
+from dataclasses import dataclass, replace
+from typing import Any
+
+from nanobot.bus.events import OutboundMessage
+
+
+class OutboundEvent:
+    """Marker base for internal outbound runtime events."""
+
+
+@dataclass(frozen=True)
+class ProgressEvent(OutboundEvent):
+    content: str = ""
+    tool_hint: bool = False
+    reasoning: bool = False
+    reasoning_delta: bool = False
+    reasoning_end: bool = False
+    stream_id: str | None = None
+    tool_events: list[dict[str, Any]] | None = None
+    file_edit_events: list[dict[str, Any]] | None = None
+
+
+@dataclass(frozen=True)
+class RetryWaitEvent(OutboundEvent):
+    content: str = ""
+
+
+@dataclass(frozen=True)
+class StreamDeltaEvent(OutboundEvent):
+    content: str = ""
+    stream_id: str | None = None
+
+
+@dataclass(frozen=True)
+class StreamEndEvent(OutboundEvent):
+    content: str = ""
+    stream_id: str | None = None
+    resuming: bool = False
+
+
+@dataclass(frozen=True)
+class StreamedResponseEvent(OutboundEvent):
+    pass
+
+
+@dataclass(frozen=True)
+class TurnEndEvent(OutboundEvent):
+    latency_ms: int | None = None
+    goal_state: dict[str, Any] | None = None
+
+
+@dataclass(frozen=True)
+class GoalStatusEvent(OutboundEvent):
+    status: str
+    started_at: float | None = None
+
+
+@dataclass(frozen=True)
+class GoalStateSyncEvent(OutboundEvent):
+    goal_state: dict[str, Any]
+
+
+@dataclass(frozen=True)
+class SessionUpdatedEvent(OutboundEvent):
+    scope: str | None = None
+
+
+@dataclass(frozen=True)
+class RuntimeModelUpdatedEvent(OutboundEvent):
+    model: str | None
+    model_preset: str | None = None
+
+
+def outbound_message_for_event(
+    *,
+    channel: str,
+    chat_id: str,
+    event: OutboundEvent,
+    content: str | None = None,
+    metadata: Mapping[str, Any] | None = None,
+) -> OutboundMessage:
+    """Build an :class:`OutboundMessage` for a typed event."""
+
+    return OutboundMessage(
+        channel=channel,
+        chat_id=chat_id,
+        content=_event_content(event) if content is None else content,
+        event=event,
+        metadata=dict(metadata or {}),
+    )
+
+
+def outbound_event_from_message(msg: OutboundMessage) -> OutboundEvent | None:
+    """Return the typed outbound event carried by *msg*, if any."""
+
+    return msg.event
+
+
+def replace_outbound_event(
+    msg: OutboundMessage,
+    event: OutboundEvent,
+    *,
+    content: str | None = None,
+) -> OutboundMessage:
+    """Return *msg* with a new event and optional content."""
+
+    return replace(
+        msg,
+        content=_event_content(event) if content is None else content,
+        event=event,
+    )
+
+
+def _event_content(event: OutboundEvent) -> str:
+    if isinstance(event, ProgressEvent | RetryWaitEvent | StreamDeltaEvent | StreamEndEvent):
+        return event.content
+    return ""

nanobot/bus/progress.py

@@ -10,7 +10,8 @@ from __future__ import annotations
 from collections.abc import Awaitable, Callable
 from typing import Any
 
-from nanobot.bus.events import InboundMessage, OutboundMessage
+from nanobot.bus.events import InboundMessage
+from nanobot.bus.outbound_events import ProgressEvent, outbound_message_for_event
 from nanobot.bus.queue import MessageBus
 
 
@@ -29,23 +30,19 @@ def build_bus_progress_callback(
         reasoning: bool = False,
         reasoning_end: bool = False,
     ) -> None:
-        meta = dict(msg.metadata or {})
-        meta["_progress"] = True
-        meta["_tool_hint"] = tool_hint
-        if reasoning:
-            meta["_reasoning_delta"] = True
-        if reasoning_end:
-            meta["_reasoning_end"] = True
-        if tool_events:
-            meta["_tool_events"] = tool_events
-        if file_edit_events:
-            meta["_file_edit_events"] = file_edit_events
         await bus.publish_outbound(
-            OutboundMessage(
+            outbound_message_for_event(
                 channel=msg.channel,
                 chat_id=msg.chat_id,
-                content=content,
-                metadata=meta,
+                event=ProgressEvent(
+                    content=content,
+                    tool_hint=tool_hint,
+                    reasoning_delta=reasoning,
+                    reasoning_end=reasoning_end,
+                    tool_events=tool_events,
+                    file_edit_events=file_edit_events,
+                ),
+                metadata=msg.metadata,
             )
         )
 

nanobot/channels/base.py

@@ -101,20 +101,33 @@ class BaseChannel(ABC):
         """
         pass
 
-    async def send_delta(self, chat_id: str, delta: str, metadata: dict[str, Any] | None = None) -> None:
+    async def send_delta(
+        self,
+        chat_id: str,
+        delta: str,
+        metadata: dict[str, Any] | None = None,
+        *,
+        stream_id: str | None = None,
+        stream_end: bool = False,
+        resuming: bool = False,
+    ) -> None:
         """Deliver a streaming text chunk.
 
         Override in subclasses to enable streaming. Implementations should
         raise on delivery failure so the channel manager can retry.
 
-        Streaming contract: ``_stream_delta`` is a chunk, ``_stream_end`` ends
-        the current segment, and stateful implementations must key buffers by
-        ``_stream_id`` rather than only by ``chat_id``.
+        Stateful implementations should key buffers by ``stream_id`` rather
+        than only by ``chat_id`` when it is provided.
         """
         pass
 
     async def send_reasoning_delta(
-        self, chat_id: str, delta: str, metadata: dict[str, Any] | None = None
+        self,
+        chat_id: str,
+        delta: str,
+        metadata: dict[str, Any] | None = None,
+        *,
+        stream_id: str | None = None,
     ) -> None:
         """Stream a chunk of model reasoning/thinking content.
 
@@ -123,15 +136,17 @@ class BaseChannel(ABC):
         subtext, WebUI italic bubble, ...) override to render reasoning
         as a subordinate trace that updates in place as the model thinks.
 
-        Streaming contract mirrors :meth:`send_delta`: ``_reasoning_delta``
-        is a chunk, ``_reasoning_end`` ends the current reasoning segment,
-        and stateful implementations should key buffers by ``_stream_id``
-        rather than only by ``chat_id``.
+        Streaming contract mirrors :meth:`send_delta`: stateful implementations
+        should key buffers by ``stream_id`` rather than only by ``chat_id``.
         """
         return
 
     async def send_reasoning_end(
-        self, chat_id: str, metadata: dict[str, Any] | None = None
+        self,
+        chat_id: str,
+        metadata: dict[str, Any] | None = None,
+        *,
+        stream_id: str | None = None,
     ) -> None:
         """Mark the end of a reasoning stream segment.
 
@@ -165,13 +180,18 @@ class BaseChannel(ABC):
         """
         if not msg.content:
             return
-        meta = dict(msg.metadata or {})
-        meta.setdefault("_reasoning_delta", True)
-        await self.send_reasoning_delta(msg.chat_id, msg.content, meta)
-        end_meta = dict(meta)
-        end_meta.pop("_reasoning_delta", None)
-        end_meta["_reasoning_end"] = True
-        await self.send_reasoning_end(msg.chat_id, end_meta)
+        stream_id = getattr(msg.event, "stream_id", None)
+        await self.send_reasoning_delta(
+            msg.chat_id,
+            msg.content,
+            msg.metadata,
+            stream_id=stream_id,
+        )
+        await self.send_reasoning_end(
+            msg.chat_id,
+            msg.metadata,
+            stream_id=stream_id,
+        )
 
     @property
     def supports_streaming(self) -> bool:

nanobot/channels/discord.py

@@ -13,6 +13,7 @@ from typing import TYPE_CHECKING, Any, Literal
 from pydantic import Field
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.command.builtin import build_help_text
@@ -458,7 +459,7 @@ class DiscordChannel(BaseChannel):
             self.logger.warning("client not ready; dropping outbound message")
             return
 
-        is_progress = bool((msg.metadata or {}).get("_progress"))
+        is_progress = isinstance(msg.event, ProgressEvent)
 
         try:
             await client.send_outbound(msg)
@@ -471,7 +472,14 @@ class DiscordChannel(BaseChannel):
                 await self._clear_reactions(msg.chat_id)
 
     async def send_delta(
-        self, chat_id: str, delta: str, metadata: dict[str, Any] | None = None
+        self,
+        chat_id: str,
+        delta: str,
+        metadata: dict[str, Any] | None = None,
+        *,
+        stream_id: str | None = None,
+        stream_end: bool = False,
+        resuming: bool = False,
     ) -> None:
         """Progressive Discord delivery: send once, then edit until the stream ends."""
         client = self._client
@@ -479,10 +487,7 @@ class DiscordChannel(BaseChannel):
             self.logger.warning("client not ready; dropping stream delta")
             return
 
-        meta = metadata or {}
-        stream_id = meta.get("_stream_id")
-
-        if meta.get("_stream_end"):
+        if stream_end:
             buf = self._stream_bufs.get(chat_id)
             if not buf or buf.message is None or not buf.text:
                 return

nanobot/channels/email.py

@@ -23,6 +23,7 @@ from loguru import logger
 from pydantic import Field
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.config.paths import get_media_dir
@@ -218,7 +219,7 @@ class EmailChannel(BaseChannel):
             return
 
         # Skip progress messages to prevent sending an empty email after each tool call
-        if (msg.metadata or {}).get("_progress"):
+        if isinstance(msg.event, ProgressEvent):
             self.logger.debug("Skip progress message to {}", msg.chat_id)
             return
 

nanobot/channels/feishu.py

@@ -22,6 +22,7 @@ from rich.panel import Panel
 from rich.text import Text
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.config.paths import get_media_dir
@@ -1797,14 +1798,19 @@ class FeishuChannel(BaseChannel):
         return self._stream_update_text_sync(card_id, content, sequence), sequence
 
     async def send_delta(
-        self, chat_id: str, delta: str, metadata: dict[str, Any] | None = None
+        self,
+        chat_id: str,
+        delta: str,
+        metadata: dict[str, Any] | None = None,
+        *,
+        stream_id: str | None = None,
+        stream_end: bool = False,
+        resuming: bool = False,
     ) -> None:
         """Progressive streaming via CardKit: create card on first delta, stream-update on subsequent.
 
         Supported metadata keys:
-            _stream_end: Finalize the streaming card.
-            _tool_hint:  Delta is a formatted tool hint (for display only).
-            message_id:  Original message id (used with _stream_end for reaction cleanup).
+            message_id:  Original message id (used with stream end for reaction cleanup).
             chat_type:   "group" or "p2p" — controls reply-in-thread for streaming cards.
         """
         if not self._client:
@@ -1815,14 +1821,14 @@ class FeishuChannel(BaseChannel):
         rid_type = "chat_id" if chat_id.startswith("oc_") else "open_id"
 
         # --- stream end: final update or fallback ---
-        if meta.get("_stream_end"):
+        if stream_end:
             message_id = meta.get("message_id")
             # Only finalize the OnIt -> DONE reaction transition on the truly
-            # final stream end. _resuming=True means the agent will keep
+            # final stream end. resuming=True means the agent will keep
             # working (more tool-call rounds), so leave the reaction state
             # in place — otherwise the OnIt indicator disappears prematurely
             # and the DONE reaction fires after every tool call.
-            if message_id and not meta.get("_resuming"):
+            if message_id and not resuming:
                 reaction_id = self._reaction_ids.pop(message_id, None)
                 if reaction_id:
                     await self._remove_reaction(message_id, reaction_id)
@@ -1965,7 +1971,9 @@ class FeishuChannel(BaseChannel):
             # Handle tool hint messages.  When a streaming card is active for
             # this chat, inline the hint into the card instead of sending a
             # separate message so the user experience stays cohesive.
-            if msg.metadata.get("_tool_hint"):
+            progress_event = msg.event if isinstance(msg.event, ProgressEvent) else None
+
+            if progress_event and progress_event.tool_hint:
                 hint = (msg.content or "").strip()
                 if not hint:
                     return
@@ -1976,6 +1984,7 @@ class FeishuChannel(BaseChannel):
                     await self.send_delta(
                         msg.chat_id,
                         "\n\n" + self._format_tool_hint_delta(hint) + "\n\n",
+                        metadata=msg.metadata,
                     )
                     return
                 # No active streaming card — send as a regular interactive card
@@ -2009,7 +2018,7 @@ class FeishuChannel(BaseChannel):
             reply_message_id: str | None = None
             _msg_id = msg.metadata.get("message_id")
             has_thread_id = msg.metadata.get("thread_id")
-            if self.config.reply_to_message and not msg.metadata.get("_progress", False):
+            if self.config.reply_to_message and progress_event is None:
                 reply_message_id = _msg_id
             # For topic group messages, always reply to keep context in thread
             elif has_thread_id:

nanobot/channels/manager.py

@@ -12,6 +12,16 @@ from typing import TYPE_CHECKING, Any
 from loguru import logger
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import (
+    ProgressEvent,
+    RetryWaitEvent,
+    RuntimeModelUpdatedEvent,
+    StreamDeltaEvent,
+    StreamedResponseEvent,
+    StreamEndEvent,
+    outbound_event_from_message,
+    replace_outbound_event,
+)
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.config.schema import Config
@@ -266,7 +276,7 @@ class ChannelManager:
 
     def _should_suppress_outbound(self, msg: OutboundMessage) -> bool:
         metadata = msg.metadata or {}
-        if metadata.get("_progress"):
+        if isinstance(outbound_event_from_message(msg), ProgressEvent):
             return False
         fingerprint = self._fingerprint_content(msg.content)
         if not fingerprint:
@@ -305,57 +315,59 @@ class ChannelManager:
                         timeout=1.0
                     )
 
-                if (
-                    msg.metadata.get("_reasoning_delta")
-                    or msg.metadata.get("_reasoning_end")
-                    or msg.metadata.get("_reasoning")
+                event = outbound_event_from_message(msg)
+                progress_event = event if isinstance(event, ProgressEvent) else None
+                if progress_event and (
+                    progress_event.reasoning_delta
+                    or progress_event.reasoning_end
+                    or progress_event.reasoning
                 ):
                     # Reasoning rides its own plugin channel: only delivered
                     # when the destination channel opts in via ``show_reasoning``
                     # and overrides the streaming primitives. Channels without
                     # a low-emphasis UI affordance keep the base no-op and the
-                    # content silently drops here. ``_reasoning`` (one-shot)
-                    # is accepted for backward compatibility with hooks that
-                    # haven't migrated to delta/end yet.
+                    # content silently drops here.
                     channel = self.channels.get(msg.channel)
                     if channel is not None and channel.show_reasoning:
                         await self._send_with_retry(channel, msg)
                     continue
 
-                if msg.metadata.get("_progress"):
-                    if msg.metadata.get("_tool_hint") and not self._should_send_progress(
+                if progress_event:
+                    if progress_event.tool_hint and not self._should_send_progress(
                         msg.channel, tool_hint=True,
                     ):
                         continue
-                    if not msg.metadata.get("_tool_hint") and not self._should_send_progress(
+                    if not progress_event.tool_hint and not self._should_send_progress(
                         msg.channel, tool_hint=False,
                     ):
                         continue
 
-                if msg.metadata.get("_retry_wait"):
+                if isinstance(event, RetryWaitEvent):
                     continue
 
                 if (
-                    msg.metadata.get("_runtime_model_updated")
+                    isinstance(event, RuntimeModelUpdatedEvent)
                     and msg.channel == "websocket"
                     and "websocket" not in self.channels
                 ):
                     continue
 
-                # Coalesce consecutive _stream_delta messages for the same (channel, chat_id)
+                # Coalesce consecutive stream delta messages for the same (channel, chat_id)
                 # to reduce API calls and improve streaming latency
-                if msg.metadata.get("_stream_delta") and not msg.metadata.get("_stream_end"):
+                if isinstance(event, StreamDeltaEvent):
                     msg, extra_pending = self._coalesce_stream_deltas(msg)
                     pending.extend(extra_pending)
+                    event = outbound_event_from_message(msg)
 
                 channel = self.channels.get(msg.channel)
                 if channel:
                     # Duplicate suppression is scoped to a known source message
                     # so repeated content from separate turns is still delivered.
                     if (
-                        not msg.metadata.get("_stream_delta")
-                        and not msg.metadata.get("_stream_end")
-                        and not msg.metadata.get("_streamed")
+                        not isinstance(
+                            event,
+                            StreamDeltaEvent | StreamEndEvent | StreamedResponseEvent,
+                        )
                     ):
                         if self._should_suppress_outbound(msg):
                             logger.info("Suppressing duplicate outbound message to {}:{}", msg.channel, msg.chat_id)
@@ -372,31 +384,53 @@ class ChannelManager:
     @staticmethod
     async def _send_once(channel: BaseChannel, msg: OutboundMessage) -> None:
         """Send one outbound message without retry policy."""
-        if msg.metadata.get("_reasoning_end"):
-            await channel.send_reasoning_end(msg.chat_id, msg.metadata)
-        elif msg.metadata.get("_reasoning_delta"):
-            await channel.send_reasoning_delta(msg.chat_id, msg.content, msg.metadata)
-        elif msg.metadata.get("_reasoning"):
-            # Back-compat: one-shot reasoning. BaseChannel translates this
-            # to a single delta + end pair so plugins only implement the
-            # streaming primitives.
+        event = outbound_event_from_message(msg)
+        if isinstance(event, ProgressEvent) and event.reasoning_end:
+            await channel.send_reasoning_end(
+                msg.chat_id,
+                msg.metadata,
+                stream_id=event.stream_id,
+            )
+        elif isinstance(event, ProgressEvent) and event.reasoning_delta:
+            await channel.send_reasoning_delta(
+                msg.chat_id,
+                msg.content,
+                msg.metadata,
+                stream_id=event.stream_id,
+            )
+        elif isinstance(event, ProgressEvent) and event.reasoning:
+            # BaseChannel translates one-shot reasoning to a single delta +
+            # end pair so plugins only implement the streaming primitives.
             await channel.send_reasoning(msg)
-        elif msg.metadata.get("_file_edit_events"):
-            edits = msg.metadata.get("_file_edit_events")
+        elif isinstance(event, ProgressEvent) and event.file_edit_events:
             await channel.send_file_edit_events(
                 msg.chat_id,
-                edits if isinstance(edits, list) else [],
+                event.file_edit_events,
                 msg.metadata,
             )
-        elif msg.metadata.get("_stream_delta") or msg.metadata.get("_stream_end"):
-            await channel.send_delta(msg.chat_id, msg.content, msg.metadata)
-        elif not msg.metadata.get("_streamed"):
+        elif isinstance(event, StreamDeltaEvent):
+            await channel.send_delta(
+                msg.chat_id,
+                msg.content,
+                msg.metadata,
+                stream_id=event.stream_id,
+            )
+        elif isinstance(event, StreamEndEvent):
+            await channel.send_delta(
+                msg.chat_id,
+                msg.content,
+                msg.metadata,
+                stream_id=event.stream_id,
+                stream_end=True,
+                resuming=event.resuming,
+            )
+        elif not isinstance(event, StreamedResponseEvent):
             await channel.send(msg)
 
     def _coalesce_stream_deltas(
         self, first_msg: OutboundMessage
     ) -> tuple[OutboundMessage, list[OutboundMessage]]:
-        """Merge consecutive _stream_delta messages for the same (channel, chat_id, _stream_id).
+        """Merge consecutive stream deltas for the same (channel, chat_id, stream_id).
 
         This reduces the number of API calls when the queue has accumulated multiple
         deltas, which happens when LLM generates faster than the channel can process.
@@ -404,10 +438,15 @@ class ChannelManager:
         Returns:
             tuple of (merged_message, list_of_non_matching_messages)
         """
-        first_metadata = first_msg.metadata or {}
-        target_key = (first_msg.channel, first_msg.chat_id, first_metadata.get("_stream_id"))
+        first_event = outbound_event_from_message(first_msg)
+        first_stream_id = first_event.stream_id if isinstance(first_event, StreamDeltaEvent) else None
+        target_key = (first_msg.channel, first_msg.chat_id, first_stream_id)
         combined_content = first_msg.content
-        final_metadata = dict(first_msg.metadata or {})
+        final_event: StreamDeltaEvent | StreamEndEvent = (
+            first_event
+            if isinstance(first_event, StreamDeltaEvent)
+            else StreamDeltaEvent(stream_id=first_stream_id)
+        )
         non_matching: list[OutboundMessage] = []
 
         # Only merge consecutive deltas. As soon as we hit any other message,
@@ -419,21 +458,29 @@ class ChannelManager:
                 break
 
             # Check if this message belongs to the same stream
-            next_metadata = next_msg.metadata or {}
+            next_event = outbound_event_from_message(next_msg)
+            next_stream_id = (
+                next_event.stream_id
+                if isinstance(next_event, StreamDeltaEvent | StreamEndEvent)
+                else None
+            )
             same_target = (
                 next_msg.channel,
                 next_msg.chat_id,
-                next_metadata.get("_stream_id"),
+                next_stream_id,
             ) == target_key
-            is_delta = next_metadata.get("_stream_delta")
-            is_end = next_metadata.get("_stream_end")
+            is_delta = isinstance(next_event, StreamDeltaEvent)
+            is_end = isinstance(next_event, StreamEndEvent)
 
-            if same_target and is_delta and not final_metadata.get("_stream_end"):
+            if same_target and (is_delta or (is_end and next_msg.content)):
                 # Accumulate content
                 combined_content += next_msg.content
-                # If we see _stream_end, remember it and stop coalescing this stream
-                if is_end:
-                    final_metadata["_stream_end"] = True
+                # If we see stream_end, remember it and stop coalescing this stream
+                if isinstance(next_event, StreamEndEvent):
+                    final_event = StreamEndEvent(
+                        stream_id=next_stream_id,
+                        resuming=next_event.resuming,
+                    )
                     # Stream ended - stop coalescing this stream
                     break
             else:
@@ -441,12 +488,7 @@ class ChannelManager:
                 non_matching.append(next_msg)
                 break
 
-        merged = OutboundMessage(
-            channel=first_msg.channel,
-            chat_id=first_msg.chat_id,
-            content=combined_content,
-            metadata=final_metadata,
-        )
+        merged = replace_outbound_event(first_msg, final_event, content=combined_content)
         return merged, non_matching
 
     async def _send_with_retry(self, channel: BaseChannel, msg: OutboundMessage) -> None:

nanobot/channels/matrix.py

@@ -49,6 +49,7 @@ except ImportError as e:
     ) from e
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.config.paths import get_data_dir, get_media_dir
@@ -504,7 +505,7 @@ class MatrixChannel(BaseChannel):
         text = msg.content or ""
         candidates = self._collect_outbound_media_candidates(msg.media)
         relates_to = self._build_thread_relates_to(msg.metadata)
-        is_progress = bool((msg.metadata or {}).get("_progress"))
+        is_progress = isinstance(msg.event, ProgressEvent)
         try:
             failures: list[str] = []
             if candidates:
@@ -528,11 +529,19 @@ class MatrixChannel(BaseChannel):
             if not is_progress:
                 await self._stop_typing_keepalive(msg.chat_id, clear_typing=True)
 
-    async def send_delta(self, chat_id: str, delta: str, metadata: dict[str, Any] | None = None) -> None:
-        meta = metadata or {}
+    async def send_delta(
+        self,
+        chat_id: str,
+        delta: str,
+        metadata: dict[str, Any] | None = None,
+        *,
+        stream_id: str | None = None,
+        stream_end: bool = False,
+        resuming: bool = False,
+    ) -> None:
         relates_to = self._build_thread_relates_to(metadata)
 
-        if meta.get("_stream_end"):
+        if stream_end:
             buf = self._stream_bufs.pop(chat_id, None)
             if not buf or not buf.event_id or not buf.text:
                 return

nanobot/channels/signal.py

@@ -18,6 +18,7 @@ import httpx
 from pydantic import Field, computed_field, field_validator
 
 from nanobot.bus.events import InboundMessage, OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.config.paths import get_media_dir
@@ -539,7 +540,7 @@ class SignalChannel(BaseChannel):
 
     async def send(self, msg: OutboundMessage) -> None:
         """Send a message through Signal."""
-        is_progress_message = bool(msg.metadata.get("_progress"))
+        is_progress_message = isinstance(msg.event, ProgressEvent)
         try:
             plain_text, text_styles = _markdown_to_signal(msg.content)
             if not plain_text and not msg.media:

nanobot/channels/slack.py

@@ -14,6 +14,7 @@ from slack_sdk.web.async_client import AsyncWebClient
 from slackify_markdown import slackify_markdown
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.config.paths import get_media_dir
@@ -164,7 +165,7 @@ class SlackChannel(BaseChannel):
             # only makes sense within the originating conversation.
             thread_ts_param = thread_ts if thread_ts and target_chat_id == origin_chat_id else None
 
-            is_progress = (msg.metadata or {}).get("_progress", False)
+            is_progress = isinstance(msg.event, ProgressEvent)
             if is_progress and not msg.content:
                 pass  # skip empty progress messages (e.g. tool-event-only updates)
             elif msg.content or not (msg.media or []):
@@ -190,7 +191,7 @@ class SlackChannel(BaseChannel):
                     self.logger.exception("Failed to upload file {}", media_path)
 
             # Update reaction emoji when the final (non-progress) response is sent
-            if not (msg.metadata or {}).get("_progress"):
+            if not is_progress:
                 event = slack_meta.get("event", {})
                 await self._update_react_emoji(origin_chat_id, event.get("ts"))
 

nanobot/channels/telegram.py

@@ -26,6 +26,7 @@ from telegram.ext import Application, CallbackQueryHandler, ContextTypes, Messag
 from telegram.request import HTTPXRequest
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.command.builtin import build_help_text
@@ -36,7 +37,7 @@ from nanobot.utils.helpers import split_message
 
 TELEGRAM_MAX_MESSAGE_LEN = 4000  # Telegram message character limit
 # Telegram's actual API limit is 4096; we split raw markdown at 4000 as a
-# safety margin for mid-stream edits (plain text).  For _stream_end, we split
+# safety margin for mid-stream edits (plain text).  On stream end, we split
 # raw markdown into chunks whose rendered HTML fits Telegram's true 4096-char
 # boundary so the final rendered message never overflows.
 TELEGRAM_HTML_MAX_LEN = 4096
@@ -706,8 +707,10 @@ class TelegramChannel(BaseChannel):
             self.logger.warning("bot not running")
             return
 
+        progress_event = msg.event if isinstance(msg.event, ProgressEvent) else None
+
         # Only stop typing indicator and remove reaction for final responses
-        if not msg.metadata.get("_progress", False):
+        if progress_event is None:
             self._stop_typing(msg.chat_id)
             if reply_to_message_id := msg.metadata.get("message_id"):
                 with suppress(ValueError):
@@ -792,7 +795,7 @@ class TelegramChannel(BaseChannel):
 
         # Send text content
         if msg.content and msg.content != "[empty message]":
-            render_as_blockquote = bool(msg.metadata.get("_tool_hint"))
+            render_as_blockquote = bool(progress_event and progress_event.tool_hint)
             buttons = getattr(msg, "buttons", None) or []
             reply_markup = self._build_keyboard(buttons) if buttons else None
             text = msg.content
@@ -887,15 +890,23 @@ class TelegramChannel(BaseChannel):
     def _is_not_modified_error(exc: Exception) -> bool:
         return isinstance(exc, BadRequest) and "message is not modified" in str(exc).lower()
 
-    async def send_delta(self, chat_id: str, delta: str, metadata: dict[str, Any] | None = None) -> None:
+    async def send_delta(
+        self,
+        chat_id: str,
+        delta: str,
+        metadata: dict[str, Any] | None = None,
+        *,
+        stream_id: str | None = None,
+        stream_end: bool = False,
+        resuming: bool = False,
+    ) -> None:
         """Progressive message editing: send on first delta, edit on subsequent ones."""
         if not self._app:
             return
         meta = metadata or {}
         int_chat_id = int(chat_id)
-        stream_id = meta.get("_stream_id")
 
-        if meta.get("_stream_end"):
+        if stream_end:
             buf = self._stream_bufs.get(chat_id)
             if not buf or not buf.message_id or not buf.text:
                 return

nanobot/channels/websocket.py

@@ -19,6 +19,16 @@ from websockets.exceptions import ConnectionClosed
 from websockets.http11 import Request as WsRequest
 
 from nanobot.bus.events import OUTBOUND_META_AGENT_UI, OutboundMessage
+from nanobot.bus.outbound_events import (
+    GoalStateSyncEvent,
+    GoalStatusEvent,
+    ProgressEvent,
+    RuntimeModelUpdatedEvent,
+    SessionUpdatedEvent,
+    TurnEndEvent,
+    outbound_event_from_message,
+    outbound_message_for_event,
+)
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.config.paths import get_media_dir
@@ -148,16 +158,13 @@ def publish_runtime_model_update(
     model_preset: str | None,
 ) -> None:
     """Enqueue a runtime model snapshot for websocket subscribers (fan-out in-channel)."""
-    bus.outbound.put_nowait(OutboundMessage(
-        channel="websocket",
-        chat_id="*",
-        content="",
-        metadata={
-            "_runtime_model_updated": True,
-            "model": model,
-            "model_preset": model_preset,
-        },
-    ))
+    bus.outbound.put_nowait(
+        outbound_message_for_event(
+            channel="websocket",
+            chat_id="*",
+            event=RuntimeModelUpdatedEvent(model=model, model_preset=model_preset),
+        )
+    )
 
 
 def _parse_inbound_payload(raw: str) -> str | None:
@@ -851,70 +858,63 @@ class WebSocketChannel(BaseChannel):
             raise
 
     async def send(self, msg: OutboundMessage) -> None:
-        if msg.metadata.get("_runtime_model_updated"):
+        event = outbound_event_from_message(msg)
+        progress_event = event if isinstance(event, ProgressEvent) else None
+        if isinstance(event, RuntimeModelUpdatedEvent):
             await self.send_runtime_model_updated(
-                model_name=msg.metadata.get("model"),
-                model_preset=msg.metadata.get("model_preset"),
+                model_name=event.model,
+                model_preset=event.model_preset,
             )
             return
 
         # Snapshot the subscriber set so ConnectionClosed cleanups mid-iteration are safe.
         conns = list(self._subs.get(msg.chat_id, ()))
         if not conns:
-            if (
-                msg.metadata.get("_progress")
-                or msg.metadata.get("_file_edit_events")
-                or msg.metadata.get("_turn_end")
-                or msg.metadata.get("_session_updated")
-                or msg.metadata.get("_goal_status")
-                or msg.metadata.get("_goal_state_sync")
+            if isinstance(
+                event,
+                ProgressEvent
+                | TurnEndEvent
+                | SessionUpdatedEvent
+                | GoalStatusEvent
+                | GoalStateSyncEvent,
             ):
                 self.logger.debug("no active subscribers for chat_id={}", msg.chat_id)
             else:
                 self.logger.warning("no active subscribers for chat_id={}", msg.chat_id)
-        if msg.metadata.get("_goal_state_sync"):
+        if isinstance(event, GoalStateSyncEvent):
             if conns:
-                blob = msg.metadata.get("goal_state")
-                await self.send_goal_state(msg.chat_id, blob if isinstance(blob, dict) else {"active": False})
+                await self.send_goal_state(msg.chat_id, event.goal_state or {"active": False})
             return
-        if msg.metadata.get("_goal_status"):
+        if isinstance(event, GoalStatusEvent):
             if conns:
-                status = msg.metadata.get("goal_status")
-                if status in ("running", "idle"):
-                    started_raw = msg.metadata.get("started_at", msg.metadata.get("goal_started_at"))
+                if event.status in ("running", "idle"):
                     await self.send_goal_status(
                         msg.chat_id,
-                        status,
-                        started_at=float(started_raw) if isinstance(started_raw, int | float) else None,
+                        event.status,
+                        started_at=event.started_at,
                     )
             return
         # Signal that the agent has fully finished processing the current turn.
-        if msg.metadata.get("_turn_end"):
-            lat = msg.metadata.get("latency_ms")
-            lat_i = int(lat) if isinstance(lat, (int, float)) else None
-            gs = msg.metadata.get("goal_state")
-            gs_blob = gs if isinstance(gs, dict) else None
+        if isinstance(event, TurnEndEvent):
             await self.send_turn_end(
                 msg.chat_id,
-                latency_ms=lat_i,
-                goal_state=gs_blob,
+                latency_ms=event.latency_ms,
+                goal_state=event.goal_state,
                 metadata=msg.metadata,
             )
             await self.send_session_updated(msg.chat_id, scope="thread")
             return
-        if msg.metadata.get("_session_updated"):
+        if isinstance(event, SessionUpdatedEvent):
             if conns:
-                scope = msg.metadata.get("_session_update_scope")
                 await self.send_session_updated(
                     msg.chat_id,
-                    scope=scope if isinstance(scope, str) else None,
+                    scope=event.scope,
                 )
             return
-        if msg.metadata.get("_file_edit_events"):
-            edits = msg.metadata.get("_file_edit_events")
+        if progress_event and progress_event.file_edit_events:
             await self.send_file_edit_events(
                 msg.chat_id,
-                edits if isinstance(edits, list) else [],
+                progress_event.file_edit_events,
                 msg.metadata,
             )
             return
@@ -939,17 +939,17 @@ class WebSocketChannel(BaseChannel):
         lat = msg.metadata.get("latency_ms")
         if isinstance(lat, (int, float)):
             payload["latency_ms"] = int(lat)
-        if msg.metadata.get("_tool_events"):
-            payload["tool_events"] = msg.metadata["_tool_events"]
+        if progress_event and progress_event.tool_events:
+            payload["tool_events"] = progress_event.tool_events
         agent_ui = msg.metadata.get(OUTBOUND_META_AGENT_UI)
         if agent_ui is not None:
             payload["agent_ui"] = agent_ui
         # Mark intermediate agent breadcrumbs (tool-call hints, generic
         # progress strings) so WS clients can render them as subordinate
         # trace rows rather than conversational replies.
-        if msg.metadata.get("_tool_hint"):
+        if progress_event and progress_event.tool_hint:
             payload["kind"] = "tool_hint"
-        elif msg.metadata.get("_progress"):
+        elif progress_event:
             payload["kind"] = "progress"
         phase = "activity" if payload.get("kind") in ("tool_hint", "progress") else "answer"
         self._transcripts.prepare_and_append(
@@ -971,6 +971,8 @@ class WebSocketChannel(BaseChannel):
         chat_id: str,
         delta: str,
         metadata: dict[str, Any] | None = None,
+        *,
+        stream_id: str | None = None,
     ) -> None:
         """Push one chunk of model reasoning. Mirrors ``send_delta`` shape so
         clients receive a stream that opens, updates in place, and closes —
@@ -986,7 +988,6 @@ class WebSocketChannel(BaseChannel):
             "chat_id": chat_id,
             "text": delta,
         }
-        stream_id = meta.get("_stream_id")
         if stream_id is not None:
             body["stream_id"] = stream_id
         self._transcripts.prepare_and_append(
@@ -1005,6 +1006,8 @@ class WebSocketChannel(BaseChannel):
         self,
         chat_id: str,
         metadata: dict[str, Any] | None = None,
+        *,
+        stream_id: str | None = None,
     ) -> None:
         """Close the current reasoning stream segment for in-place renderers."""
         conns = list(self._subs.get(chat_id, ()))
@@ -1013,7 +1016,6 @@ class WebSocketChannel(BaseChannel):
             "event": "reasoning_end",
             "chat_id": chat_id,
         }
-        stream_id = meta.get("_stream_id")
         if stream_id is not None:
             body["stream_id"] = stream_id
         self._transcripts.prepare_and_append(
@@ -1057,11 +1059,15 @@ class WebSocketChannel(BaseChannel):
         chat_id: str,
         delta: str,
         metadata: dict[str, Any] | None = None,
+        *,
+        stream_id: str | None = None,
+        stream_end: bool = False,
+        resuming: bool = False,
     ) -> None:
         conns = list(self._subs.get(chat_id, ()))
         meta = metadata or {}
-        stream_key = (chat_id, str(meta.get("_stream_id") or ""))
-        if meta.get("_stream_end"):
+        stream_key = (chat_id, str(stream_id or ""))
+        if stream_end:
             body: dict[str, Any] = {"event": "stream_end", "chat_id": chat_id}
             buffered = self._stream_text_buffers.pop(stream_key, [])
             if delta:
@@ -1077,8 +1083,8 @@ class WebSocketChannel(BaseChannel):
                 "text": delta,
             }
             self._stream_text_buffers.setdefault(stream_key, []).append(delta)
-        if meta.get("_stream_id") is not None:
-            body["stream_id"] = meta["_stream_id"]
+        if stream_id is not None:
+            body["stream_id"] = stream_id
         self._transcripts.prepare_and_append(
             chat_id,
             body,

nanobot/channels/wecom.py

@@ -13,6 +13,7 @@ from typing import Any
 from pydantic import Field
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.config.paths import get_media_dir
@@ -497,7 +498,7 @@ class WecomChannel(BaseChannel):
 
         try:
             content = (msg.content or "").strip()
-            is_progress = bool(msg.metadata.get("_progress"))
+            is_progress = isinstance(msg.event, ProgressEvent)
 
             # Get the stored frame for this chat
             frame = self._chat_frames.get(msg.chat_id)

nanobot/channels/weixin.py

@@ -29,6 +29,7 @@ from loguru import logger
 from pydantic import Field
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.config.paths import get_media_dir, get_runtime_subdir
@@ -1101,11 +1102,13 @@ class WeixinChannel(BaseChannel):
             raise RuntimeError("WeChat client not initialized or not authenticated")
         self._assert_session_active()
 
-        is_progress = bool((msg.metadata or {}).get("_progress", False))
+        event = getattr(msg, "event", None)
+        progress_event = event if isinstance(event, ProgressEvent) else None
+        is_progress = progress_event is not None
 
         # Buffer tool hints to coalesce consecutive ones and avoid burning
         # WeChat iLink rate-limit quota (~7 msgs / 5 min).
-        if is_progress and (msg.metadata or {}).get("_tool_hint"):
+        if progress_event and progress_event.tool_hint:
             if not self.send_tool_hints:
                 return
             self._pending_tool_hints.setdefault(msg.chat_id, []).append(msg.content)
@@ -1118,7 +1121,7 @@ class WeixinChannel(BaseChannel):
 
         # Reasoning deltas are invisible in WeChat (there is no reasoning
         # UI).  Skip them entirely — do not send and do not flush buffer.
-        if is_progress and (msg.metadata or {}).get("_reasoning_delta"):
+        if progress_event and (progress_event.reasoning_delta or progress_event.reasoning):
             self.logger.debug(
                 "Dropped invisible reasoning delta for {}", msg.chat_id
             )
@@ -1232,40 +1235,46 @@ class WeixinChannel(BaseChannel):
                     await self._send_typing(msg.chat_id, typing_ticket, TYPING_STATUS_CANCEL)
 
     async def send_delta(
-        self, chat_id: str, delta: str, metadata: dict[str, Any] | None = None
+        self,
+        chat_id: str,
+        delta: str,
+        metadata: dict[str, Any] | None = None,
+        *,
+        stream_id: str | None = None,
+        stream_end: bool = False,
+        resuming: bool = False,
     ) -> None:
         """Deliver a streamed reply to WeChat.
 
         WeChat iLink has no native incremental delivery, and the manager
         bypasses :meth:`send` for the ``_streamed`` final answer. So we
-        accumulate the content deltas here and flush the full reply as a
-        single message at ``_stream_end`` — otherwise a streamed reply would
-        never reach the user. Reasoning deltas are invisible in WeChat and are
-        dropped.
+        accumulate content deltas and flush the full reply as a single message
+        at stream end. Reasoning deltas are invisible in WeChat and are dropped.
         """
         meta = metadata or {}
         if meta.get("_reasoning_delta") or meta.get("_reasoning"):
             return
-        is_end = meta.get("_stream_end")
-        # Accumulate intermediate deltas. The _stream_end message's own content
+        is_end = stream_end or bool(meta.get("_stream_end"))
+        buffer_key = stream_id or chat_id
+        # Accumulate intermediate deltas. The stream_end message's own content
         # (present when the manager coalesces deltas into the end message) is
         # folded into `full` below instead of appended here, so a send retry
         # recomputes the same `full` from an unchanged buffer rather than
         # double-counting that delta.
         if delta and not is_end:
-            self._stream_buffers.setdefault(chat_id, []).append(delta)
+            self._stream_buffers.setdefault(buffer_key, []).append(delta)
         if not is_end:
             return
-        full = ("".join(self._stream_buffers.get(chat_id, [])) + (delta or "")).strip()
+        full = ("".join(self._stream_buffers.get(buffer_key, [])) + (delta or "")).strip()
         await self._flush_tool_hints(chat_id)
         if full:
             # Send before clearing the buffer: if the send raises, the buffer is
             # left intact so ChannelManager._send_with_retry can re-deliver the
-            # same _stream_end message instead of silently losing the reply.
+            # same stream_end message instead of silently losing the reply.
             await self.send(
                 OutboundMessage(channel=self.name, chat_id=chat_id, content=full)
             )
-        self._stream_buffers.pop(chat_id, None)
+        self._stream_buffers.pop(buffer_key, None)
 
     async def _start_typing(self, chat_id: str, context_token: str = "") -> None:
         """Start typing indicator immediately when a message is received."""

nanobot/cli/commands.py

@@ -50,6 +50,14 @@ from rich.text import Text  # noqa: E402
 
 from nanobot import __logo__, __version__  # noqa: E402
 from nanobot.agent.loop import AgentLoop  # noqa: E402
+from nanobot.bus.outbound_events import (  # noqa: E402
+    ProgressEvent,
+    RetryWaitEvent,
+    StreamDeltaEvent,
+    StreamedResponseEvent,
+    StreamEndEvent,
+    outbound_event_from_message,
+)
 from nanobot.cli.gateway import create_gateway_app  # noqa: E402
 from nanobot.cli.stream import StreamRenderer, ThinkingSpinner  # noqa: E402
 from nanobot.config.paths import get_workspace_path, is_default_workspace  # noqa: E402
@@ -461,25 +469,25 @@ async def _maybe_print_interactive_progress(
     renderer: StreamRenderer | None = None,
     reasoning_buffer: _ReasoningBuffer | None = None,
 ) -> bool:
-    metadata = msg.metadata or {}
-    if metadata.get("_retry_wait"):
+    event = outbound_event_from_message(msg)
+    if isinstance(event, RetryWaitEvent):
         await _print_interactive_progress_line(msg.content, thinking, renderer)
         return True
 
-    if not metadata.get("_progress"):
+    if not isinstance(event, ProgressEvent):
         return False
 
     reasoning_buffer = reasoning_buffer or _ReasoningBuffer()
 
-    if metadata.get("_reasoning_end"):
+    if event.reasoning_end:
         if channels_config and not channels_config.show_reasoning:
             reasoning_buffer.clear()
         else:
             _flush_cli_reasoning(reasoning_buffer, thinking, renderer)
         return True
 
-    is_tool_hint = metadata.get("_tool_hint", False)
-    is_reasoning = metadata.get("_reasoning", False) or metadata.get("_reasoning_delta", False)
+    is_tool_hint = event.tool_hint
+    is_reasoning = event.reasoning or event.reasoning_delta
     if is_reasoning:
         if channels_config and not channels_config.show_reasoning:
             reasoning_buffer.clear()
@@ -1456,7 +1464,7 @@ def agent(
             bus_task = asyncio.create_task(agent_loop.run())
             turn_done = asyncio.Event()
             turn_done.set()
-            turn_response: list[tuple[str, dict]] = []
+            turn_response: list[Any] = []
             renderer: StreamRenderer | None = None
             reasoning_buffer = _ReasoningBuffer()
 
@@ -1464,18 +1472,19 @@ def agent(
                 while True:
                     try:
                         msg = await asyncio.wait_for(bus.consume_outbound(), timeout=1.0)
+                        event = outbound_event_from_message(msg)
 
-                        if msg.metadata.get("_stream_delta"):
+                        if isinstance(event, StreamDeltaEvent):
                             if renderer:
                                 await renderer.on_delta(msg.content)
                             continue
-                        if msg.metadata.get("_stream_end"):
+                        if isinstance(event, StreamEndEvent):
                             if renderer:
                                 await renderer.on_end(
-                                    resuming=msg.metadata.get("_resuming", False),
+                                    resuming=event.resuming,
                                 )
                             continue
-                        if msg.metadata.get("_streamed"):
+                        if isinstance(event, StreamedResponseEvent):
                             turn_done.set()
                             continue
 
@@ -1490,7 +1499,7 @@ def agent(
 
                         if not turn_done.is_set():
                             if msg.content:
-                                turn_response.append((msg.content, dict(msg.metadata or {})))
+                                turn_response.append(msg)
                             turn_done.set()
                         elif msg.content:
                             await _print_interactive_response(
@@ -1543,8 +1552,10 @@ def agent(
                         await turn_done.wait()
 
                         if turn_response:
-                            content, meta = turn_response[0]
-                            if content and not meta.get("_streamed"):
+                            response_msg = turn_response[0]
+                            content = response_msg.content
+                            meta = response_msg.metadata
+                            if content and not isinstance(response_msg.event, StreamedResponseEvent):
                                 if renderer:
                                     await renderer.close()
                                 print_kwargs: dict[str, Any] = {}

nanobot/session/turn_continuation.py

@@ -29,10 +29,6 @@ _GOAL_CONTINUATION_SENDER = "system:continuation"
 _GOAL_CONTINUATION_ROUNDS_KEY = "_sustained_goal_continuation_rounds"
 _MAX_GOAL_CONTINUATION_ROUNDS = 12
 _STRIPPED_INBOUND_META_KEYS = {
-    "_stream_id",
-    "_stream_delta",
-    "_stream_end",
-    "_resuming",
     INTERNAL_CONTINUATION_PENDING_META,
 }
 

nanobot/session/webui_turns.py

@@ -11,7 +11,15 @@ from typing import Any
 from loguru import logger
 
 from nanobot.bus import progress as bus_progress
-from nanobot.bus.events import InboundMessage, OutboundMessage
+from nanobot.bus.events import InboundMessage
+from nanobot.bus.outbound_events import (
+    GoalStateSyncEvent,
+    GoalStatusEvent,
+    RuntimeModelUpdatedEvent,
+    SessionUpdatedEvent,
+    TurnEndEvent,
+    outbound_message_for_event,
+)
 from nanobot.bus.queue import MessageBus
 from nanobot.bus.runtime_events import (
     GoalStateChanged,
@@ -206,26 +214,22 @@ async def publish_turn_run_status(
     if msg.channel != "websocket":
         return
     cid = str(msg.chat_id)
-    meta: dict[str, Any] = {
-        **dict(msg.metadata or {}),
-        "_goal_status": True,
-        "goal_status": status,
-    }
+    started_at_event: float | None = None
     if status == "running":
         if isinstance(started_at, int | float) and started_at > 0:
             t0 = float(started_at)
         else:
             t0 = time.time()
-        meta["started_at"] = t0
+        started_at_event = t0
         _WEBSOCKET_TURN_WALL_STARTED_AT[cid] = t0
     else:
         _WEBSOCKET_TURN_WALL_STARTED_AT.pop(cid, None)
     await bus.publish_outbound(
-        OutboundMessage(
+        outbound_message_for_event(
             channel=msg.channel,
             chat_id=cid,
-            content="",
-            metadata=meta,
+            event=GoalStatusEvent(status=status, started_at=started_at_event),
+            metadata=msg.metadata,
         ),
     )
 
@@ -318,28 +322,25 @@ class WebuiTurnCoordinator:
         if not cid:
             return
         await self.bus.publish_outbound(
-            OutboundMessage(
+            outbound_message_for_event(
                 channel=event.context.channel,
                 chat_id=cid,
-                content="",
-                metadata={
-                    "_goal_state_sync": True,
-                    "goal_state": goal_state_ws_blob(event.session_metadata),
-                },
+                event=GoalStateSyncEvent(
+                    goal_state=goal_state_ws_blob(event.session_metadata),
+                ),
+                metadata=event.context.metadata,
             ),
         )
 
     async def _handle_runtime_model_changed(self, event: RuntimeModelChanged) -> None:
         await self.bus.publish_outbound(
-            OutboundMessage(
+            outbound_message_for_event(
                 channel="websocket",
                 chat_id="*",
-                content="",
-                metadata={
-                    "_runtime_model_updated": True,
-                    "model": event.model,
-                    "model_preset": event.model_preset,
-                },
+                event=RuntimeModelUpdatedEvent(
+                    model=event.model,
+                    model_preset=event.model_preset,
+                ),
             )
         )
 
@@ -374,17 +375,18 @@ class WebuiTurnCoordinator:
         if msg.channel != "websocket":
             return
 
-        turn_metadata: dict[str, Any] = {**msg.metadata, "_turn_end": True}
-        if latency_ms is not None:
-            turn_metadata["latency_ms"] = int(latency_ms)
         session = self.sessions.get_or_create(session_key)
-        turn_metadata["goal_state"] = goal_state_ws_blob(session.metadata)
-        await self.bus.publish_outbound(OutboundMessage(
-            channel=msg.channel,
-            chat_id=msg.chat_id,
-            content="",
-            metadata=turn_metadata,
-        ))
+        await self.bus.publish_outbound(
+            outbound_message_for_event(
+                channel=msg.channel,
+                chat_id=msg.chat_id,
+                event=TurnEndEvent(
+                    latency_ms=latency_ms,
+                    goal_state=goal_state_ws_blob(session.metadata),
+                ),
+                metadata=msg.metadata,
+            )
+        )
         self._schedule_title_update(msg, session_key=session_key)
 
     def _schedule_title_update(self, msg: InboundMessage, *, session_key: str) -> None:
@@ -404,16 +406,11 @@ class WebuiTurnCoordinator:
                 model=title_llm.model,
             )
             if generated:
-                await self.bus.publish_outbound(OutboundMessage(
+                await self._publish_session_metadata_updated(
                     channel=msg.channel,
                     chat_id=msg.chat_id,
-                    content="",
-                    metadata={
-                        **msg.metadata,
-                        "_session_updated": True,
-                        "_session_update_scope": "metadata",
-                    },
-                ))
+                    metadata=msg.metadata,
+                )
 
         self.schedule_background(_generate_title_and_notify())
 
@@ -438,15 +435,26 @@ class WebuiTurnCoordinator:
                 model=title_llm.model,
             )
             if generated:
-                await self.bus.publish_outbound(OutboundMessage(
+                await self._publish_session_metadata_updated(
                     channel=event.context.channel,
                     chat_id=event.context.chat_id,
-                    content="",
-                    metadata={
-                        **event.context.metadata,
-                        "_session_updated": True,
-                        "_session_update_scope": "metadata",
-                    },
-                ))
+                    metadata=event.context.metadata,
+                )
 
         self.schedule_background(_generate_title_and_notify())
+
+    async def _publish_session_metadata_updated(
+        self,
+        *,
+        channel: str,
+        chat_id: str,
+        metadata: dict[str, Any],
+    ) -> None:
+        await self.bus.publish_outbound(
+            outbound_message_for_event(
+                channel=channel,
+                chat_id=chat_id,
+                event=SessionUpdatedEvent(scope="metadata"),
+                metadata=metadata,
+            )
+        )

tests/agent/test_loop_direct_websocket_status.py

@@ -5,6 +5,7 @@ import pytest
 
 from nanobot.agent.loop import AgentLoop
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import GoalStatusEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.providers.base import GenerationSettings, LLMResponse
 from nanobot.session.webui_turns import WebuiTurnCoordinator
@@ -54,13 +55,13 @@ async def test_process_direct_websocket_clears_run_status(tmp_path) -> None:
         events.append(await loop.bus.consume_outbound())
 
     statuses = [
-        event.metadata
+        event.event
         for event in events
-        if event.metadata.get("_goal_status") is True
+        if isinstance(event.event, GoalStatusEvent)
     ]
-    assert [status["goal_status"] for status in statuses] == ["running", "idle"]
-    assert isinstance(statuses[0].get("started_at"), float)
-    assert "started_at" not in statuses[1]
+    assert [status.status for status in statuses] == ["running", "idle"]
+    assert isinstance(statuses[0].started_at, float)
+    assert statuses[1].started_at is None
 
 
 @pytest.mark.asyncio

tests/agent/test_loop_progress.py

@@ -9,6 +9,15 @@ import pytest
 import nanobot.agent.runner as runner_module
 from nanobot.agent.loop import AgentLoop
 from nanobot.bus.events import InboundMessage
+from nanobot.bus.outbound_events import (
+    GoalStatusEvent,
+    ProgressEvent,
+    SessionUpdatedEvent,
+    StreamDeltaEvent,
+    StreamedResponseEvent,
+    StreamEndEvent,
+    TurnEndEvent,
+)
 from nanobot.bus.queue import MessageBus
 from nanobot.providers.base import LLMResponse, ToolCallRequest
 from nanobot.session.webui_turns import WebuiTurnCoordinator
@@ -260,25 +269,45 @@ class TestToolEventProgress:
         )
         await loop._dispatch(msg)
 
-        # Drain all outbound messages and find the one carrying _tool_events
+        # Drain all outbound messages and find the one carrying tool events.
         outbound = []
         while bus.outbound_size > 0:
             outbound.append(await bus.consume_outbound())
 
-        tool_event_msgs = [m for m in outbound if m.metadata and m.metadata.get("_tool_events")]
-        assert tool_event_msgs, "expected at least one outbound message with _tool_events"
+        tool_event_msgs = [
+            m
+            for m in outbound
+            if isinstance(m.event, ProgressEvent) and m.event.tool_events
+        ]
+        assert tool_event_msgs, "expected at least one outbound message with tool events"
 
-        start_msgs = [m for m in tool_event_msgs if m.metadata["_tool_events"][0]["phase"] == "start"]
-        finish_msgs = [m for m in tool_event_msgs if m.metadata["_tool_events"][0]["phase"] in ("end", "error")]
+        start_msgs = [
+            m
+            for m in tool_event_msgs
+            if isinstance(m.event, ProgressEvent)
+            and m.event.tool_events
+            and m.event.tool_events[0]["phase"] == "start"
+        ]
+        finish_msgs = [
+            m
+            for m in tool_event_msgs
+            if isinstance(m.event, ProgressEvent)
+            and m.event.tool_events
+            and m.event.tool_events[0]["phase"] in ("end", "error")
+        ]
         assert start_msgs, "expected a start-phase tool event"
         assert finish_msgs, "expected a finish-phase tool event"
 
-        start = start_msgs[0].metadata["_tool_events"][0]
+        assert isinstance(start_msgs[0].event, ProgressEvent)
+        assert start_msgs[0].event.tool_events is not None
+        start = start_msgs[0].event.tool_events[0]
         assert start["name"] == "exec"
         assert start["call_id"] == "tc1"
         assert start["result"] is None
 
-        finish = finish_msgs[0].metadata["_tool_events"][0]
+        assert isinstance(finish_msgs[0].event, ProgressEvent)
+        assert finish_msgs[0].event.tool_events is not None
+        finish = finish_msgs[0].event.tool_events[0]
         assert finish["phase"] == "end"
         assert finish["result"] == "file.txt"
 
@@ -309,7 +338,8 @@ class TestToolEventProgress:
         await invoke_file_edit_progress(progress, edit_events)
         outbound = await bus.consume_outbound()
         assert outbound.channel == "telegram"
-        assert outbound.metadata["_file_edit_events"] == edit_events
+        assert isinstance(outbound.event, ProgressEvent)
+        assert outbound.event.file_edit_events == edit_events
 
     @pytest.mark.asyncio
     async def test_goal_turn_keeps_live_file_edit_progress_for_webui(self, tmp_path: Path) -> None:
@@ -389,7 +419,8 @@ class TestToolEventProgress:
         edit_events = [
             event
             for msg in outbound
-            for event in msg.metadata.get("_file_edit_events", [])
+            if isinstance(msg.event, ProgressEvent)
+            for event in msg.event.file_edit_events or []
         ]
         assert any(
             event["status"] == "editing"
@@ -433,8 +464,8 @@ class TestToolEventProgress:
             outbound.append(await bus.consume_outbound())
 
         assert [m.content for m in outbound] == ["Hello"]
-        assert not any(m.metadata.get("_progress") for m in outbound)
-        assert not any(m.metadata.get("_streamed") for m in outbound)
+        assert not any(isinstance(m.event, ProgressEvent) for m in outbound)
+        assert not any(isinstance(m.event, StreamedResponseEvent) for m in outbound)
         provider.chat_stream_with_retry.assert_not_awaited()
         provider.chat_with_retry.assert_awaited_once()
 
@@ -443,7 +474,7 @@ class TestToolEventProgress:
         self,
         tmp_path: Path,
     ) -> None:
-        """Streaming channels still receive provider deltas through _stream_delta messages."""
+        """Streaming channels still receive provider deltas through stream events."""
         bus = MessageBus()
         provider = MagicMock()
         provider.supports_progress_deltas = True
@@ -473,21 +504,19 @@ class TestToolEventProgress:
         while bus.outbound_size > 0:
             outbound.append(await bus.consume_outbound())
 
-        deltas = [m for m in outbound if m.metadata.get("_stream_delta")]
-        stream_end = [m for m in outbound if m.metadata.get("_stream_end")]
+        deltas = [m for m in outbound if isinstance(m.event, StreamDeltaEvent)]
+        stream_end = [m for m in outbound if isinstance(m.event, StreamEndEvent)]
         final = [
             m for m in outbound
-            if not m.metadata.get("_stream_delta")
-            and not m.metadata.get("_stream_end")
-            and not m.metadata.get("_turn_end")
-            and not m.metadata.get("_goal_status")
+            if not isinstance(m.event, StreamDeltaEvent | StreamEndEvent)
+            and not isinstance(m.event, TurnEndEvent | GoalStatusEvent)
         ]
 
         assert [m.content for m in deltas] == ["Hel", "lo"]
         assert len(stream_end) == 1
         assert final[-1].content == "Hello"
-        assert final[-1].metadata.get("_streamed") is True
-        turn_end_msgs = [m for m in outbound if m.metadata.get("_turn_end")]
+        assert isinstance(final[-1].event, StreamedResponseEvent)
+        turn_end_msgs = [m for m in outbound if isinstance(m.event, TurnEndEvent)]
         assert len(turn_end_msgs) == 1
         assert turn_end_msgs[0].content == ""
         provider.chat_with_retry.assert_not_awaited()
@@ -528,23 +557,28 @@ class TestToolEventProgress:
         while bus.outbound_size > 0:
             outbound.append(await bus.consume_outbound())
 
-        deltas = [m for m in outbound if m.metadata.get("_stream_delta")]
-        stream_end = [m for m in outbound if m.metadata.get("_stream_end")]
+        deltas = [m for m in outbound if isinstance(m.event, StreamDeltaEvent)]
+        stream_end = [m for m in outbound if isinstance(m.event, StreamEndEvent)]
         final = [
             m for m in outbound
-            if not m.metadata.get("_stream_delta")
-            and not m.metadata.get("_stream_end")
-            and not m.metadata.get("_turn_end")
-            and not m.metadata.get("_goal_status")
+            if not isinstance(m.event, StreamDeltaEvent | StreamEndEvent)
+            and not isinstance(m.event, TurnEndEvent | GoalStatusEvent)
         ]
 
         assert [m.content for m in deltas] == ["partial", "full retry response"]
-        assert [m.metadata.get("_resuming") for m in stream_end] == [True, False]
-        assert deltas[0].metadata.get("_stream_id") == stream_end[0].metadata.get("_stream_id")
-        assert deltas[1].metadata.get("_stream_id") == stream_end[1].metadata.get("_stream_id")
-        assert deltas[0].metadata.get("_stream_id") != deltas[1].metadata.get("_stream_id")
+        assert [m.event.resuming for m in stream_end if isinstance(m.event, StreamEndEvent)] == [
+            True,
+            False,
+        ]
+        assert isinstance(deltas[0].event, StreamDeltaEvent)
+        assert isinstance(deltas[1].event, StreamDeltaEvent)
+        assert isinstance(stream_end[0].event, StreamEndEvent)
+        assert isinstance(stream_end[1].event, StreamEndEvent)
+        assert deltas[0].event.stream_id == stream_end[0].event.stream_id
+        assert deltas[1].event.stream_id == stream_end[1].event.stream_id
+        assert deltas[0].event.stream_id != deltas[1].event.stream_id
         assert final[-1].content == "full retry response"
-        assert final[-1].metadata.get("_streamed") is True
+        assert isinstance(final[-1].event, StreamedResponseEvent)
         provider.chat_with_retry.assert_not_awaited()
 
     @pytest.mark.asyncio
@@ -623,9 +657,9 @@ class TestToolEventProgress:
 
         done_msgs = [m for m in outbound if m.content == "Done"]
         assert len(done_msgs) == 1
-        assert not done_msgs[0].metadata.get("_turn_end")
+        assert not isinstance(done_msgs[0].event, TurnEndEvent)
 
-        turn_end_msgs = [m for m in outbound if m.metadata.get("_turn_end")]
+        turn_end_msgs = [m for m in outbound if isinstance(m.event, TurnEndEvent)]
         assert len(turn_end_msgs) == 1
         assert turn_end_msgs[0].content == ""
         assert turn_end_msgs[0].chat_id == "chat1"
@@ -659,14 +693,14 @@ class TestToolEventProgress:
             outbound.append(await bus.consume_outbound())
 
         error_msgs = [m for m in outbound if m.content == "Sorry, I encountered an error."]
-        turn_end_msgs = [m for m in outbound if m.metadata.get("_turn_end")]
-        statuses = [m for m in outbound if m.metadata.get("_goal_status")]
+        turn_end_msgs = [m for m in outbound if isinstance(m.event, TurnEndEvent)]
+        statuses = [m for m in outbound if isinstance(m.event, GoalStatusEvent)]
 
         assert len(error_msgs) == 1
         assert len(turn_end_msgs) == 1
         assert turn_end_msgs[0].content == ""
         assert turn_end_msgs[0].chat_id == "chat1"
-        assert [m.metadata["goal_status"] for m in statuses] == ["idle"]
+        assert [m.event.status for m in statuses if isinstance(m.event, GoalStatusEvent)] == ["idle"]
         assert outbound.index(error_msgs[0]) < outbound.index(turn_end_msgs[0])
         assert outbound.index(turn_end_msgs[0]) < outbound.index(statuses[-1])
 
@@ -705,27 +739,27 @@ class TestToolEventProgress:
         outbound: list = []
         for _ in range(12):
             outbound.append(await asyncio.wait_for(bus.consume_outbound(), timeout=0.5))
-            if outbound[-1].metadata.get("_turn_end"):
+            if isinstance(outbound[-1].event, TurnEndEvent):
                 break
         else:
-            raise AssertionError("_turn_end message not found")
+            raise AssertionError("turn-end event not found")
 
         done_with_body = [m for m in outbound if m.content == "Done"]
         assert len(done_with_body) == 1
-        assert outbound[-1].metadata.get("_turn_end") is True
+        assert isinstance(outbound[-1].event, TurnEndEvent)
 
         await asyncio.wait_for(title_started.wait(), timeout=0.5)
         release_title.set()
         session_updated = None
         for _ in range(10):
             candidate = await asyncio.wait_for(bus.consume_outbound(), timeout=0.5)
-            if (candidate.metadata or {}).get("_session_updated"):
+            if isinstance(candidate.event, SessionUpdatedEvent):
                 session_updated = candidate
                 break
         assert session_updated is not None
 
-        assert (session_updated.metadata or {}).get("_session_updated") is True
-        assert (session_updated.metadata or {}).get("_session_update_scope") == "metadata"
+        assert isinstance(session_updated.event, SessionUpdatedEvent)
+        assert session_updated.event.scope == "metadata"
         assert provider.chat_with_retry.await_count == 2
 
     @pytest.mark.asyncio
@@ -837,4 +871,4 @@ class TestToolEventProgress:
 
         assert len(outbound) == 1
         assert outbound[0].content == "Done"
-        assert (outbound[0].metadata or {}).get("_turn_end") is not True
+        assert not isinstance(outbound[0].event, TurnEndEvent)

tests/agent/test_loop_runner_integration.py

@@ -7,6 +7,7 @@ from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
 
+from nanobot.bus.outbound_events import StreamedResponseEvent
 from nanobot.config.schema import AgentDefaults
 from nanobot.providers.base import LLMResponse, ToolCallRequest
 
@@ -23,8 +24,8 @@ def _make_loop(tmp_path):
 
     with patch("nanobot.agent.loop.ContextBuilder"), \
          patch("nanobot.agent.loop.SessionManager"), \
-         patch("nanobot.agent.loop.SubagentManager") as MockSubMgr:
-        MockSubMgr.return_value.cancel_by_session = AsyncMock(return_value=0)
+         patch("nanobot.agent.loop.SubagentManager") as mock_sub_mgr:
+        mock_sub_mgr.return_value.cancel_by_session = AsyncMock(return_value=0)
         loop = AgentLoop(bus=bus, provider=provider, workspace=tmp_path)
     return loop
 
@@ -193,8 +194,9 @@ async def test_streamed_flag_not_set_on_llm_error(tmp_path):
 
     assert result is not None
     assert "503" in result.content
-    assert not result.metadata.get("_streamed"), \
-        "_streamed must not be set when stop_reason is error"
+    assert not isinstance(result.event, StreamedResponseEvent), (
+        "streamed response event must not be set when stop_reason is error"
+    )
 
 
 @pytest.mark.asyncio
@@ -239,7 +241,7 @@ async def test_ssrf_soft_block_can_finalize_after_streamed_tool_call(tmp_path):
 
     assert result is not None
     assert result.content == "I cannot access private URLs. Please share the local file."
-    assert result.metadata.get("_streamed") is True
+    assert isinstance(result.event, StreamedResponseEvent)
 
 
 @pytest.mark.asyncio

tests/agent/test_loop_save_turn.py

@@ -8,6 +8,13 @@ import pytest
 from nanobot.agent.context import ContextBuilder
 from nanobot.agent.loop import AgentLoop
 from nanobot.bus.events import InboundMessage
+from nanobot.bus.outbound_events import (
+    GoalStatusEvent,
+    StreamDeltaEvent,
+    StreamedResponseEvent,
+    StreamEndEvent,
+    TurnEndEvent,
+)
 from nanobot.bus.queue import MessageBus
 from nanobot.cron.session_turns import CRON_HISTORY_META, CRON_TRIGGER_META
 from nanobot.providers.base import LLMResponse
@@ -765,7 +772,6 @@ async def test_internal_continuation_preserves_streaming_route_metadata(
             "_wants_stream": True,
             "message_id": "om_001",
             "origin_message_id": "root_001",
-            "_stream_id": "old-stream",
         },
     ))
 
@@ -775,23 +781,23 @@ async def test_internal_continuation_preserves_streaming_route_metadata(
     assert queued.metadata["_wants_stream"] is True
     assert queued.metadata["message_id"] == "om_001"
     assert queued.metadata["origin_message_id"] == "root_001"
-    assert "_stream_id" not in queued.metadata
 
     await loop._dispatch(queued)
 
     outbound = []
     while loop.bus.outbound_size:
         outbound.append(await loop.bus.consume_outbound())
-    deltas = [m for m in outbound if m.metadata.get("_stream_delta")]
-    ends = [m for m in outbound if m.metadata.get("_stream_end")]
-    streamed_markers = [m for m in outbound if m.metadata.get("_streamed")]
+    deltas = [m for m in outbound if isinstance(m.event, StreamDeltaEvent)]
+    ends = [m for m in outbound if isinstance(m.event, StreamEndEvent)]
+    streamed_markers = [m for m in outbound if isinstance(m.event, StreamedResponseEvent)]
 
     assert [m.content for m in deltas] == ["done"]
     assert len(ends) == 1
-    assert ends[0].metadata["_resuming"] is False
+    assert isinstance(ends[0].event, StreamEndEvent)
+    assert ends[0].event.resuming is False
     assert ends[0].metadata["message_id"] == "om_001"
     assert ends[0].metadata["origin_message_id"] == "root_001"
-    assert isinstance(ends[0].metadata.get("_stream_id"), str)
+    assert isinstance(ends[0].event.stream_id, str)
     assert streamed_markers and streamed_markers[-1].content == "done"
 
 
@@ -842,10 +848,10 @@ async def test_websocket_internal_continuation_keeps_single_visible_run(
     first_outbound = []
     while loop.bus.outbound_size:
         first_outbound.append(await loop.bus.consume_outbound())
-    first_statuses = [m.metadata for m in first_outbound if m.metadata.get("_goal_status")]
-    assert [m["goal_status"] for m in first_statuses] == ["running"]
-    assert not [m for m in first_outbound if m.metadata.get("_turn_end")]
-    started_at = first_statuses[0]["started_at"]
+    first_statuses = [m.event for m in first_outbound if isinstance(m.event, GoalStatusEvent)]
+    assert [m.status for m in first_statuses] == ["running"]
+    assert not [m for m in first_outbound if isinstance(m.event, TurnEndEvent)]
+    started_at = first_statuses[0].started_at
 
     queued = await asyncio.wait_for(loop.bus.consume_inbound(), timeout=0.5)
     assert queued.metadata[INTERNAL_CONTINUATION_META] is True
@@ -856,12 +862,13 @@ async def test_websocket_internal_continuation_keeps_single_visible_run(
     second_outbound = []
     while loop.bus.outbound_size:
         second_outbound.append(await loop.bus.consume_outbound())
-    second_statuses = [m.metadata for m in second_outbound if m.metadata.get("_goal_status")]
-    assert [m["goal_status"] for m in second_statuses] == ["running", "idle"]
-    assert second_statuses[0]["started_at"] == started_at
-    turn_end = [m for m in second_outbound if m.metadata.get("_turn_end")]
+    second_statuses = [m.event for m in second_outbound if isinstance(m.event, GoalStatusEvent)]
+    assert [m.status for m in second_statuses] == ["running", "idle"]
+    assert second_statuses[0].started_at == started_at
+    turn_end = [m for m in second_outbound if isinstance(m.event, TurnEndEvent)]
     assert len(turn_end) == 1
-    assert isinstance(turn_end[0].metadata.get("latency_ms"), int)
+    assert isinstance(turn_end[0].event, TurnEndEvent)
+    assert isinstance(turn_end[0].event.latency_ms, int)
 
 
 @pytest.mark.asyncio

tests/agent/test_task_cancel.py

@@ -127,6 +127,7 @@ class TestDispatch:
     @pytest.mark.asyncio
     async def test_dispatch_streaming_preserves_message_metadata(self):
         from nanobot.bus.events import InboundMessage
+        from nanobot.bus.outbound_events import StreamDeltaEvent, StreamEndEvent
 
         loop, bus = _make_loop()
         msg = InboundMessage(
@@ -156,10 +157,10 @@ class TestDispatch:
 
         assert first.metadata["thread_root_event_id"] == "$root1"
         assert first.metadata["thread_reply_to_event_id"] == "$reply1"
-        assert first.metadata["_stream_delta"] is True
+        assert isinstance(first.event, StreamDeltaEvent)
         assert second.metadata["thread_root_event_id"] == "$root1"
         assert second.metadata["thread_reply_to_event_id"] == "$reply1"
-        assert second.metadata["_stream_end"] is True
+        assert isinstance(second.event, StreamEndEvent)
 
     @pytest.mark.asyncio
     async def test_processing_lock_serializes(self):

tests/agent/tools/test_long_task.py

@@ -13,6 +13,7 @@ from nanobot.agent.tools.long_task import (
     CompleteGoalTool,
     LongTaskTool,
 )
+from nanobot.bus.outbound_events import GoalStateSyncEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.bus.runtime_events import RuntimeEventBus
 from nanobot.session.goal_state import GOAL_STATE_KEY
@@ -144,8 +145,8 @@ async def test_long_task_publishes_goal_state_ws_after_save(tmp_path):
     call = bus.publish_outbound.await_args.args[0]
     assert call.channel == "websocket"
     assert call.chat_id == "chat-99"
-    assert call.metadata.get("_goal_state_sync") is True
-    assert call.metadata["goal_state"] == {
+    assert isinstance(call.event, GoalStateSyncEvent)
+    assert call.event.goal_state == {
         "active": True,
         "ui_summary": "alpha",
         "objective": "Objective alpha",
@@ -180,7 +181,8 @@ async def test_complete_goal_publishes_inactive_goal_state_ws(tmp_path):
 
     bus.publish_outbound.assert_awaited_once()
     call = bus.publish_outbound.await_args.args[0]
-    assert call.metadata["goal_state"] == {"active": False}
+    assert isinstance(call.event, GoalStateSyncEvent)
+    assert call.event.goal_state == {"active": False}
 
 
 @pytest.mark.asyncio

tests/bus/test_outbound_events.py

@@ -0,0 +1,98 @@
+from __future__ import annotations
+
+from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import (
+    ProgressEvent,
+    StreamDeltaEvent,
+    StreamedResponseEvent,
+    StreamEndEvent,
+    outbound_event_from_message,
+    outbound_message_for_event,
+    replace_outbound_event,
+)
+
+
+def test_progress_event_lives_on_outbound_message_event_field() -> None:
+    tool_events = [{"phase": "start", "name": "read_file"}]
+    file_edit_events = [{"phase": "end", "path": "app.py"}]
+
+    msg = outbound_message_for_event(
+        channel="websocket",
+        chat_id="chat-1",
+        event=ProgressEvent(
+            content="working",
+            tool_hint=True,
+            reasoning_delta=True,
+            stream_id="r1",
+            tool_events=tool_events,
+            file_edit_events=file_edit_events,
+        ),
+        metadata={"origin_message_id": "m1"},
+    )
+
+    assert msg.content == "working"
+    assert msg.metadata == {"origin_message_id": "m1"}
+
+    event = outbound_event_from_message(msg)
+    assert isinstance(event, ProgressEvent)
+    assert event.content == "working"
+    assert event.tool_hint is True
+    assert event.reasoning_delta is True
+    assert event.stream_id == "r1"
+    assert event.tool_events == tool_events
+    assert event.file_edit_events == file_edit_events
+
+
+def test_normal_outbound_message_has_no_runtime_event() -> None:
+    msg = OutboundMessage(channel="websocket", chat_id="chat-1", content="hello")
+
+    assert outbound_event_from_message(msg) is None
+
+
+def test_metadata_flags_do_not_create_runtime_events() -> None:
+    msg = OutboundMessage(
+        channel="websocket",
+        chat_id="chat-1",
+        content="legacy progress",
+        metadata={
+            "_progress": True,
+            "_stream_delta": True,
+            "_goal_status": True,
+            "message_id": "platform-routing-context",
+        },
+    )
+
+    assert outbound_event_from_message(msg) is None
+
+
+def test_replace_outbound_event_keeps_routing_metadata() -> None:
+    msg = outbound_message_for_event(
+        channel="websocket",
+        chat_id="chat-1",
+        event=StreamDeltaEvent(content="hello", stream_id="s1"),
+        metadata={"message_id": "m1"},
+    )
+
+    updated = replace_outbound_event(
+        msg,
+        StreamEndEvent(stream_id="s1", resuming=True),
+        content="hello world",
+    )
+
+    assert updated.content == "hello world"
+    assert updated.metadata == {"message_id": "m1"}
+    assert isinstance(updated.event, StreamEndEvent)
+    assert updated.event.stream_id == "s1"
+    assert updated.event.resuming is True
+
+
+def test_streamed_response_event_keeps_final_content_outside_event_payload() -> None:
+    msg = outbound_message_for_event(
+        channel="cli",
+        chat_id="direct",
+        event=StreamedResponseEvent(),
+        content="final answer",
+    )
+
+    assert msg.content == "final answer"
+    assert isinstance(outbound_event_from_message(msg), StreamedResponseEvent)

tests/channels/test_channel_manager_delta_coalescing.py

@@ -1,10 +1,19 @@
 """Tests for ChannelManager delta coalescing to reduce streaming latency."""
+
 import asyncio
 from unittest.mock import AsyncMock
 
 import pytest
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import (
+    ProgressEvent,
+    RetryWaitEvent,
+    StreamDeltaEvent,
+    StreamEndEvent,
+    outbound_event_from_message,
+    outbound_message_for_event,
+)
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.channels.manager import ChannelManager
@@ -29,221 +38,187 @@ class MockChannel(BaseChannel):
         pass
 
     async def send(self, msg):
-        """Implement abstract method."""
         return await self._send_mock(msg)
 
-    async def send_delta(self, chat_id, delta, metadata=None):
-        """Override send_delta for testing."""
-        return await self._send_delta_mock(chat_id, delta, metadata)
+    async def send_delta(
+        self,
+        chat_id,
+        delta,
+        metadata=None,
+        *,
+        stream_id=None,
+        stream_end=False,
+        resuming=False,
+    ):
+        return await self._send_delta_mock(
+            chat_id,
+            delta,
+            metadata,
+            stream_id=stream_id,
+            stream_end=stream_end,
+            resuming=resuming,
+        )
 
 
 @pytest.fixture
 def config():
-    """Create a minimal config for testing."""
     return Config()
 
 
 @pytest.fixture
 def bus():
-    """Create a message bus for testing."""
     return MessageBus()
 
 
 @pytest.fixture
 def manager(config, bus):
-    """Create a channel manager with a mock channel."""
     manager = ChannelManager(config, bus)
     manager.channels["mock"] = MockChannel({}, bus)
     return manager
 
 
+def _delta(content: str, *, chat_id: str = "chat1", stream_id: str | None = None):
+    return outbound_message_for_event(
+        channel="mock",
+        chat_id=chat_id,
+        event=StreamDeltaEvent(content=content, stream_id=stream_id),
+    )
+
+
+def _end(
+    content: str = "",
+    *,
+    chat_id: str = "chat1",
+    stream_id: str | None = None,
+    resuming: bool = False,
+):
+    return outbound_message_for_event(
+        channel="mock",
+        chat_id=chat_id,
+        event=StreamEndEvent(content=content, stream_id=stream_id, resuming=resuming),
+    )
+
+
 class TestDeltaCoalescing:
-    """Tests for _stream_delta message coalescing."""
+    """Tests for stream delta message coalescing."""
 
     @pytest.mark.asyncio
     async def test_single_delta_not_coalesced(self, manager, bus):
-        """A single delta should be sent as-is."""
-        msg = OutboundMessage(
-            channel="mock",
-            chat_id="chat1",
-            content="Hello",
-            metadata={"_stream_delta": True},
-        )
+        msg = _delta("Hello")
         await bus.publish_outbound(msg)
 
-        # Process one message
         async def process_one():
             try:
                 m = await asyncio.wait_for(bus.consume_outbound(), timeout=0.1)
-                if m.metadata.get("_stream_delta"):
+                event = outbound_event_from_message(m)
+                if isinstance(event, StreamDeltaEvent):
                     m, pending = manager._coalesce_stream_deltas(m)
-                    # Put pending back (none expected)
                     for p in pending:
                         await bus.publish_outbound(p)
                 channel = manager.channels.get(m.channel)
-                if channel:
-                    await channel.send_delta(m.chat_id, m.content, m.metadata)
+                event = outbound_event_from_message(m)
+                if channel and isinstance(event, StreamDeltaEvent):
+                    await channel.send_delta(
+                        m.chat_id,
+                        m.content,
+                        m.metadata,
+                        stream_id=event.stream_id,
+                    )
             except asyncio.TimeoutError:
                 pass
 
         await process_one()
 
         manager.channels["mock"]._send_delta_mock.assert_called_once_with(
-            "chat1", "Hello", {"_stream_delta": True}
+            "chat1",
+            "Hello",
+            {},
+            stream_id=None,
+            stream_end=False,
+            resuming=False,
         )
 
     @pytest.mark.asyncio
     async def test_multiple_deltas_coalesced(self, manager, bus):
-        """Multiple consecutive deltas for same chat should be merged."""
-        # Put multiple deltas in queue
         for text in ["Hello", " ", "world", "!"]:
-            await bus.publish_outbound(OutboundMessage(
-                channel="mock",
-                chat_id="chat1",
-                content=text,
-                metadata={"_stream_delta": True},
-            ))
+            await bus.publish_outbound(_delta(text))
 
-        # Process using coalescing logic
         first_msg = await bus.consume_outbound()
         merged, pending = manager._coalesce_stream_deltas(first_msg)
 
-        # Should have merged all deltas
         assert merged.content == "Hello world!"
-        assert merged.metadata.get("_stream_delta") is True
-        # No pending messages (all were coalesced)
+        assert isinstance(merged.event, StreamDeltaEvent)
         assert len(pending) == 0
 
     @pytest.mark.asyncio
     async def test_deltas_different_chats_not_coalesced(self, manager, bus):
-        """Deltas for different chats should not be merged."""
-        # Put deltas for different chats
-        await bus.publish_outbound(OutboundMessage(
-            channel="mock",
-            chat_id="chat1",
-            content="Hello",
-            metadata={"_stream_delta": True},
-        ))
-        await bus.publish_outbound(OutboundMessage(
-            channel="mock",
-            chat_id="chat2",
-            content="World",
-            metadata={"_stream_delta": True},
-        ))
+        await bus.publish_outbound(_delta("Hello", chat_id="chat1"))
+        await bus.publish_outbound(_delta("World", chat_id="chat2"))
 
         first_msg = await bus.consume_outbound()
         merged, pending = manager._coalesce_stream_deltas(first_msg)
 
-        # First chat should not include second chat's content
         assert merged.content == "Hello"
         assert merged.chat_id == "chat1"
-        # Second chat should be in pending
         assert len(pending) == 1
         assert pending[0].chat_id == "chat2"
         assert pending[0].content == "World"
 
     @pytest.mark.asyncio
     async def test_deltas_different_stream_ids_not_coalesced(self, manager, bus):
-        """Deltas for the same chat but different streams should not be merged."""
-        await bus.publish_outbound(OutboundMessage(
-            channel="mock",
-            chat_id="chat1",
-            content="A1",
-            metadata={"_stream_delta": True, "_stream_id": "stream-a"},
-        ))
-        await bus.publish_outbound(OutboundMessage(
-            channel="mock",
-            chat_id="chat1",
-            content="B1",
-            metadata={"_stream_delta": True, "_stream_id": "stream-b"},
-        ))
+        await bus.publish_outbound(_delta("A1", stream_id="stream-a"))
+        await bus.publish_outbound(_delta("B1", stream_id="stream-b"))
 
         first_msg = await bus.consume_outbound()
         merged, pending = manager._coalesce_stream_deltas(first_msg)
 
         assert merged.content == "A1"
-        assert merged.metadata.get("_stream_id") == "stream-a"
+        assert isinstance(merged.event, StreamDeltaEvent)
+        assert merged.event.stream_id == "stream-a"
         assert len(pending) == 1
         assert pending[0].content == "B1"
-        assert pending[0].metadata.get("_stream_id") == "stream-b"
+        assert isinstance(pending[0].event, StreamDeltaEvent)
+        assert pending[0].event.stream_id == "stream-b"
 
     @pytest.mark.asyncio
     async def test_stream_end_terminates_coalescing(self, manager, bus):
-        """_stream_end should stop coalescing and be included in final message."""
-        # Put deltas with stream_end at the end
-        await bus.publish_outbound(OutboundMessage(
-            channel="mock",
-            chat_id="chat1",
-            content="Hello",
-            metadata={"_stream_delta": True},
-        ))
-        await bus.publish_outbound(OutboundMessage(
-            channel="mock",
-            chat_id="chat1",
-            content=" world",
-            metadata={"_stream_delta": True, "_stream_end": True},
-        ))
+        await bus.publish_outbound(_delta("Hello"))
+        await bus.publish_outbound(_end(" world"))
 
         first_msg = await bus.consume_outbound()
         merged, pending = manager._coalesce_stream_deltas(first_msg)
 
-        # Should have merged content
         assert merged.content == "Hello world"
-        # Should have stream_end flag
-        assert merged.metadata.get("_stream_end") is True
-        # No pending
+        assert isinstance(merged.event, StreamEndEvent)
         assert len(pending) == 0
 
     @pytest.mark.asyncio
     async def test_coalescing_stops_at_first_non_matching_boundary(self, manager, bus):
-        """Only consecutive deltas should be merged; later deltas stay queued."""
-        await bus.publish_outbound(OutboundMessage(
-            channel="mock",
-            chat_id="chat1",
-            content="Hello",
-            metadata={"_stream_delta": True, "_stream_id": "seg-1"},
-        ))
-        await bus.publish_outbound(OutboundMessage(
-            channel="mock",
-            chat_id="chat1",
-            content="",
-            metadata={"_stream_end": True, "_stream_id": "seg-1"},
-        ))
-        await bus.publish_outbound(OutboundMessage(
-            channel="mock",
-            chat_id="chat1",
-            content="world",
-            metadata={"_stream_delta": True, "_stream_id": "seg-2"},
-        ))
+        await bus.publish_outbound(_delta("Hello", stream_id="seg-1"))
+        await bus.publish_outbound(_end(stream_id="seg-1"))
+        await bus.publish_outbound(_delta("world", stream_id="seg-2"))
 
         first_msg = await bus.consume_outbound()
         merged, pending = manager._coalesce_stream_deltas(first_msg)
 
         assert merged.content == "Hello"
-        assert merged.metadata.get("_stream_end") is None
+        assert isinstance(merged.event, StreamDeltaEvent)
         assert len(pending) == 1
-        assert pending[0].metadata.get("_stream_end") is True
-        assert pending[0].metadata.get("_stream_id") == "seg-1"
+        assert isinstance(pending[0].event, StreamEndEvent)
+        assert pending[0].event.stream_id == "seg-1"
 
-        # The next stream segment must remain in queue order for later dispatch.
         remaining = await bus.consume_outbound()
         assert remaining.content == "world"
-        assert remaining.metadata.get("_stream_id") == "seg-2"
+        assert isinstance(remaining.event, StreamDeltaEvent)
+        assert remaining.event.stream_id == "seg-2"
 
     @pytest.mark.asyncio
     async def test_non_delta_message_preserved(self, manager, bus):
-        """Non-delta messages should be preserved in pending list."""
-        await bus.publish_outbound(OutboundMessage(
-            channel="mock",
-            chat_id="chat1",
-            content="Delta",
-            metadata={"_stream_delta": True},
-        ))
+        await bus.publish_outbound(_delta("Delta"))
         await bus.publish_outbound(OutboundMessage(
             channel="mock",
             chat_id="chat1",
             content="Final message",
-            metadata={},  # Not a delta
         ))
 
         first_msg = await bus.consume_outbound()
@@ -252,17 +227,11 @@ class TestDeltaCoalescing:
         assert merged.content == "Delta"
         assert len(pending) == 1
         assert pending[0].content == "Final message"
-        assert pending[0].metadata.get("_stream_delta") is None
+        assert pending[0].event is None
 
     @pytest.mark.asyncio
     async def test_empty_queue_stops_coalescing(self, manager, bus):
-        """Coalescing should stop when queue is empty."""
-        await bus.publish_outbound(OutboundMessage(
-            channel="mock",
-            chat_id="chat1",
-            content="Only message",
-            metadata={"_stream_delta": True},
-        ))
+        await bus.publish_outbound(_delta("Only message"))
 
         first_msg = await bus.consume_outbound()
         merged, pending = manager._coalesce_stream_deltas(first_msg)
@@ -276,49 +245,35 @@ class TestDispatchOutboundWithCoalescing:
 
     @pytest.mark.asyncio
     async def test_dispatch_coalesces_and_processes_pending(self, manager, bus):
-        """_dispatch_outbound should coalesce deltas and process pending messages."""
-        # Put multiple deltas followed by a regular message
-        await bus.publish_outbound(OutboundMessage(
-            channel="mock",
-            chat_id="chat1",
-            content="A",
-            metadata={"_stream_delta": True},
-        ))
-        await bus.publish_outbound(OutboundMessage(
-            channel="mock",
-            chat_id="chat1",
-            content="B",
-            metadata={"_stream_delta": True},
-        ))
+        await bus.publish_outbound(_delta("A"))
+        await bus.publish_outbound(_delta("B"))
         await bus.publish_outbound(OutboundMessage(
             channel="mock",
             chat_id="chat1",
             content="Final",
-            metadata={},  # Regular message
         ))
 
-        # Run one iteration of dispatch logic manually
         pending = []
         processed = []
 
-        # First iteration: should coalesce A+B
-        if pending:
-            msg = pending.pop(0)
-        else:
-            msg = await bus.consume_outbound()
-
-        if msg.metadata.get("_stream_delta") and not msg.metadata.get("_stream_end"):
+        msg = pending.pop(0) if pending else await bus.consume_outbound()
+        event = outbound_event_from_message(msg)
+        if isinstance(event, StreamDeltaEvent):
             msg, extra_pending = manager._coalesce_stream_deltas(msg)
             pending.extend(extra_pending)
 
         channel = manager.channels.get(msg.channel)
-        if channel:
-            await channel.send_delta(msg.chat_id, msg.content, msg.metadata)
+        event = outbound_event_from_message(msg)
+        if channel and isinstance(event, StreamDeltaEvent):
+            await channel.send_delta(
+                msg.chat_id,
+                msg.content,
+                msg.metadata,
+                stream_id=event.stream_id,
+            )
             processed.append(("delta", msg.content))
 
-        # Should have sent coalesced delta
         assert processed == [("delta", "AB")]
-        # Should have pending regular message
         assert len(pending) == 1
         assert pending[0].content == "Final"
 
@@ -354,23 +309,20 @@ class TestProgressFiltering:
 
         assert manager._resolve_bool_override(FakeSection(), "send_progress", True) is False
         assert manager._resolve_bool_override(FakeSection(), "send_tool_hints", False) is True
-        # Missing attribute falls back to default
         assert manager._resolve_bool_override(FakeSection(), "unknown_key", True) is True
 
     @pytest.mark.asyncio
     async def test_channel_override_can_drop_progress_message(self, manager, bus):
         manager.channels["mock"].send_progress = False
-        await bus.publish_outbound(OutboundMessage(
+        await bus.publish_outbound(outbound_message_for_event(
             channel="mock",
             chat_id="chat1",
-            content="thinking",
-            metadata={"_progress": True},
+            event=ProgressEvent(content="thinking"),
         ))
         await bus.publish_outbound(OutboundMessage(
             channel="mock",
             chat_id="chat1",
             content="final answer",
-            metadata={},
         ))
 
         task = asyncio.create_task(manager._dispatch_outbound())
@@ -391,13 +343,41 @@ class TestProgressFiltering:
         assert send_mock.await_args_list[0].args[0].content == "final answer"
 
     @pytest.mark.asyncio
-    async def test_channel_override_can_enable_tool_hints(self, manager, bus):
-        manager.channels["mock"].send_tool_hints = True
+    async def test_metadata_only_progress_flag_is_not_runtime_progress(self, manager, bus):
+        manager.channels["mock"].send_progress = False
         await bus.publish_outbound(OutboundMessage(
             channel="mock",
             chat_id="chat1",
-            content="read_file(foo.py)",
-            metadata={"_progress": True, "_tool_hint": True},
+            content="legacy progress-shaped message",
+            metadata={"_progress": True},
+        ))
+
+        task = asyncio.create_task(manager._dispatch_outbound())
+        try:
+            for _ in range(30):
+                if manager.channels["mock"]._send_mock.await_count >= 1:
+                    break
+                await asyncio.sleep(0.05)
+        finally:
+            task.cancel()
+            try:
+                await task
+            except asyncio.CancelledError:
+                pass
+
+        send_mock = manager.channels["mock"]._send_mock
+        assert send_mock.await_count == 1
+        sent = send_mock.await_args_list[0].args[0]
+        assert sent.content == "legacy progress-shaped message"
+        assert sent.event is None
+
+    @pytest.mark.asyncio
+    async def test_channel_override_can_enable_tool_hints(self, manager, bus):
+        manager.channels["mock"].send_tool_hints = True
+        await bus.publish_outbound(outbound_message_for_event(
+            channel="mock",
+            chat_id="chat1",
+            event=ProgressEvent(content="read_file(foo.py)", tool_hint=True),
         ))
 
         task = asyncio.create_task(manager._dispatch_outbound())
@@ -423,24 +403,15 @@ class TestRetryWaitFiltering:
 
     @pytest.mark.asyncio
     async def test_retry_wait_message_dropped(self, manager, bus):
-        """A ``_retry_wait`` message must be filtered before channel dispatch.
-
-        Regression: provider retry diagnostics like
-        ``Model request failed, retry in 1s (attempt 1).`` were being
-        delivered to end-user channels because the runner bound
-        ``on_retry_wait`` to the progress callback.
-        """
-        retry_msg = OutboundMessage(
+        retry_msg = outbound_message_for_event(
             channel="mock",
             chat_id="chat1",
-            content="Model request failed, retry in 1s (attempt 1).",
-            metadata={"_retry_wait": True},
+            event=RetryWaitEvent(content="Model request failed, retry in 1s (attempt 1)."),
         )
         real_msg = OutboundMessage(
             channel="mock",
             chat_id="chat1",
             content="final answer",
-            metadata={},
         )
         await bus.publish_outbound(retry_msg)
         await bus.publish_outbound(real_msg)
@@ -462,4 +433,4 @@ class TestRetryWaitFiltering:
         assert send_mock.await_count == 1
         sent = send_mock.await_args_list[0].args[0]
         assert sent.content == "final answer"
-        assert not sent.metadata.get("_retry_wait")
+        assert sent.event is None

tests/channels/test_channel_manager_reasoning.py

@@ -8,10 +8,9 @@ channels that opt in via ``channel.show_reasoning``; plugins without a
 low-emphasis UI primitive keep the base no-op and the content silently
 drops at dispatch.
 
-One-shot ``_reasoning`` frames are accepted for back-compat with hooks
-that haven't migrated yet — ``BaseChannel.send_reasoning`` expands them
-to a single delta + end pair so plugins only implement the streaming
-primitives.
+One-shot reasoning frames are represented as typed progress events and
+``BaseChannel.send_reasoning`` expands them to a single delta + end pair so
+plugins only implement the streaming primitives.
 """
 
 from __future__ import annotations
@@ -22,6 +21,7 @@ from unittest.mock import AsyncMock
 import pytest
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent, outbound_message_for_event
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.channels.manager import ChannelManager
@@ -48,11 +48,11 @@ class _MockChannel(BaseChannel):
     async def send(self, msg):
         return await self._send_mock(msg)
 
-    async def send_reasoning_delta(self, chat_id, delta, metadata=None):
-        return await self._delta_mock(chat_id, delta, metadata)
+    async def send_reasoning_delta(self, chat_id, delta, metadata=None, *, stream_id=None):
+        return await self._delta_mock(chat_id, delta, metadata, stream_id=stream_id)
 
-    async def send_reasoning_end(self, chat_id, metadata=None):
-        return await self._end_mock(chat_id, metadata)
+    async def send_reasoning_end(self, chat_id, metadata=None, *, stream_id=None):
+        return await self._end_mock(chat_id, metadata, stream_id=stream_id)
 
     async def send_file_edit_events(self, chat_id, edits, metadata=None):
         return await self._file_edit_mock(chat_id, edits, metadata)
@@ -94,17 +94,17 @@ def test_websocket_gateway_uses_configured_workspace_restriction(tmp_path, monke
 @pytest.mark.asyncio
 async def test_reasoning_delta_routes_to_send_reasoning_delta(manager):
     channel = manager.channels["mock"]
-    msg = OutboundMessage(
+    msg = outbound_message_for_event(
         channel="mock",
         chat_id="c1",
-        content="step-by-step",
-        metadata={"_progress": True, "_reasoning_delta": True, "_stream_id": "r1"},
+        event=ProgressEvent(content="step-by-step", reasoning_delta=True, stream_id="r1"),
     )
     await manager._send_once(channel, msg)
     channel._delta_mock.assert_awaited_once()
     args = channel._delta_mock.await_args.args
     assert args[0] == "c1"
     assert args[1] == "step-by-step"
+    assert channel._delta_mock.await_args.kwargs["stream_id"] == "r1"
     channel._send_mock.assert_not_awaited()
     channel._end_mock.assert_not_awaited()
 
@@ -112,11 +112,10 @@ async def test_reasoning_delta_routes_to_send_reasoning_delta(manager):
 @pytest.mark.asyncio
 async def test_reasoning_end_routes_to_send_reasoning_end(manager):
     channel = manager.channels["mock"]
-    msg = OutboundMessage(
+    msg = outbound_message_for_event(
         channel="mock",
         chat_id="c1",
-        content="",
-        metadata={"_progress": True, "_reasoning_end": True, "_stream_id": "r1"},
+        event=ProgressEvent(reasoning_end=True, stream_id="r1"),
     )
     await manager._send_once(channel, msg)
     channel._end_mock.assert_awaited_once()
@@ -124,16 +123,13 @@ async def test_reasoning_end_routes_to_send_reasoning_end(manager):
 
 
 @pytest.mark.asyncio
-async def test_legacy_one_shot_reasoning_expands_to_delta_plus_end(manager):
-    """`_reasoning` (no delta/end pair) falls back through `send_reasoning`
-    which the base class expands to a single delta + end. Hooks that haven't
-    migrated still surface in WebUI as a complete stream segment."""
+async def test_one_shot_reasoning_expands_to_delta_plus_end(manager):
+    """One-shot reasoning expands to a single delta + end."""
     channel = manager.channels["mock"]
-    msg = OutboundMessage(
+    msg = outbound_message_for_event(
         channel="mock",
         chat_id="c1",
-        content="one-shot reasoning",
-        metadata={"_progress": True, "_reasoning": True},
+        event=ProgressEvent(content="one-shot reasoning", reasoning=True),
     )
     await manager._send_once(channel, msg)
     channel._delta_mock.assert_awaited_once()
@@ -144,11 +140,10 @@ async def test_legacy_one_shot_reasoning_expands_to_delta_plus_end(manager):
 async def test_dispatch_drops_reasoning_when_channel_opts_out(manager):
     channel = manager.channels["mock"]
     channel.show_reasoning = False
-    msg = OutboundMessage(
+    msg = outbound_message_for_event(
         channel="mock",
         chat_id="c1",
-        content="hidden thinking",
-        metadata={"_progress": True, "_reasoning_delta": True},
+        event=ProgressEvent(content="hidden thinking", reasoning_delta=True),
     )
     await manager.bus.publish_outbound(msg)
 
@@ -164,17 +159,15 @@ async def test_dispatch_delivers_reasoning_when_channel_opts_in(manager):
     channel = manager.channels["mock"]
     channel.show_reasoning = True
     for chunk in ("first ", "second"):
-        await manager.bus.publish_outbound(OutboundMessage(
+        await manager.bus.publish_outbound(outbound_message_for_event(
             channel="mock",
             chat_id="c1",
-            content=chunk,
-            metadata={"_progress": True, "_reasoning_delta": True, "_stream_id": "r1"},
+            event=ProgressEvent(content=chunk, reasoning_delta=True, stream_id="r1"),
         ))
-    await manager.bus.publish_outbound(OutboundMessage(
+    await manager.bus.publish_outbound(outbound_message_for_event(
         channel="mock",
         chat_id="c1",
-        content="",
-        metadata={"_progress": True, "_reasoning_end": True, "_stream_id": "r1"},
+        event=ProgressEvent(reasoning_end=True, stream_id="r1"),
     ))
 
     await _pump_one(manager)
@@ -185,11 +178,10 @@ async def test_dispatch_delivers_reasoning_when_channel_opts_in(manager):
 
 @pytest.mark.asyncio
 async def test_dispatch_silently_drops_reasoning_for_unknown_channel(manager):
-    msg = OutboundMessage(
+    msg = outbound_message_for_event(
         channel="ghost",
         chat_id="c1",
-        content="nobody home",
-        metadata={"_progress": True, "_reasoning_delta": True},
+        event=ProgressEvent(content="nobody home", reasoning_delta=True),
     )
     await manager.bus.publish_outbound(msg)
 
@@ -229,17 +221,34 @@ async def test_base_channel_reasoning_primitives_are_noop_safe():
 async def test_file_edit_events_route_to_channel_capability(manager):
     channel = manager.channels["mock"]
     edits = [{"version": 1, "phase": "start", "path": "src/app.py"}]
-    msg = OutboundMessage(
+    msg = outbound_message_for_event(
         channel="mock",
         chat_id="c1",
-        content="",
-        metadata={"_progress": True, "_file_edit_events": edits},
+        event=ProgressEvent(file_edit_events=edits),
     )
 
     await manager._send_once(channel, msg)
 
     channel._file_edit_mock.assert_awaited_once_with(
-        "c1", edits, {"_progress": True, "_file_edit_events": edits}
+        "c1", edits, msg.metadata
+    )
+    channel._send_mock.assert_not_awaited()
+
+
+@pytest.mark.asyncio
+async def test_typed_file_edit_event_routes_to_channel_capability(manager):
+    channel = manager.channels["mock"]
+    edits = [{"version": 1, "phase": "start", "path": "src/app.py"}]
+    msg = outbound_message_for_event(
+        channel="mock",
+        chat_id="c1",
+        event=ProgressEvent(file_edit_events=edits),
+    )
+
+    await manager._send_once(channel, msg)
+
+    channel._file_edit_mock.assert_awaited_once_with(
+        "c1", edits, msg.metadata
     )
     channel._send_mock.assert_not_awaited()
 
@@ -270,11 +279,10 @@ async def test_reasoning_routing_does_not_consult_send_progress(manager):
     channel = manager.channels["mock"]
     channel.send_progress = False
     channel.show_reasoning = True
-    await manager.bus.publish_outbound(OutboundMessage(
+    await manager.bus.publish_outbound(outbound_message_for_event(
         channel="mock",
         chat_id="c1",
-        content="still surfaces",
-        metadata={"_progress": True, "_reasoning_delta": True},
+        event=ProgressEvent(content="still surfaces", reasoning_delta=True),
     ))
 
     await _pump_one(manager)

tests/channels/test_channel_plugins.py

@@ -9,6 +9,11 @@ from unittest.mock import AsyncMock, patch
 import pytest
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import (
+    StreamDeltaEvent,
+    StreamedResponseEvent,
+    outbound_message_for_event,
+)
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
 from nanobot.channels.manager import ChannelManager
@@ -718,7 +723,7 @@ async def test_send_with_retry_no_retry_when_max_is_zero():
 
 @pytest.mark.asyncio
 async def test_send_with_retry_calls_send_delta():
-    """_send_with_retry should call send_delta when metadata has _stream_delta."""
+    """_send_with_retry should call send_delta for stream delta events."""
     send_delta_called = False
 
     class _StreamingChannel(BaseChannel):
@@ -734,7 +739,16 @@ async def test_send_with_retry_calls_send_delta():
         async def send(self, msg: OutboundMessage) -> None:
             pass  # Should not be called
 
-        async def send_delta(self, chat_id: str, delta: str, metadata: dict | None = None) -> None:
+        async def send_delta(
+            self,
+            chat_id: str,
+            delta: str,
+            metadata: dict | None = None,
+            *,
+            stream_id: str | None = None,
+            stream_end: bool = False,
+            resuming: bool = False,
+        ) -> None:
             nonlocal send_delta_called
             send_delta_called = True
 
@@ -749,9 +763,10 @@ async def test_send_with_retry_calls_send_delta():
     mgr.channels = {"streaming": _StreamingChannel(fake_config, mgr.bus)}
     mgr._dispatch_task = None
 
-    msg = OutboundMessage(
-        channel="streaming", chat_id="123", content="test delta",
-        metadata={"_stream_delta": True}
+    msg = outbound_message_for_event(
+        channel="streaming",
+        chat_id="123",
+        event=StreamDeltaEvent(content="test delta"),
     )
     await mgr._send_with_retry(mgr.channels["streaming"], msg)
 
@@ -760,7 +775,7 @@ async def test_send_with_retry_calls_send_delta():
 
 @pytest.mark.asyncio
 async def test_send_with_retry_skips_send_when_streamed():
-    """_send_with_retry should not call send when metadata has _streamed flag."""
+    """_send_with_retry should not call send for streamed response events."""
     send_called = False
     send_delta_called = False
 
@@ -778,7 +793,16 @@ async def test_send_with_retry_skips_send_when_streamed():
             nonlocal send_called
             send_called = True
 
-        async def send_delta(self, chat_id: str, delta: str, metadata: dict | None = None) -> None:
+        async def send_delta(
+            self,
+            chat_id: str,
+            delta: str,
+            metadata: dict | None = None,
+            *,
+            stream_id: str | None = None,
+            stream_end: bool = False,
+            resuming: bool = False,
+        ) -> None:
             nonlocal send_delta_called
             send_delta_called = True
 
@@ -793,10 +817,11 @@ async def test_send_with_retry_skips_send_when_streamed():
     mgr.channels = {"streamed": _StreamedChannel(fake_config, mgr.bus)}
     mgr._dispatch_task = None
 
-    # _streamed means message was already sent via send_delta, so skip send
-    msg = OutboundMessage(
-        channel="streamed", chat_id="123", content="test",
-        metadata={"_streamed": True}
+    msg = outbound_message_for_event(
+        channel="streamed",
+        chat_id="123",
+        event=StreamedResponseEvent(),
+        content="test",
     )
     await mgr._send_with_retry(mgr.channels["streamed"], msg)
 

tests/channels/test_discord_channel.py

@@ -10,6 +10,7 @@ pytest.importorskip("discord")
 import discord
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.discord import (
     MAX_MESSAGE_LEN,
@@ -718,9 +719,9 @@ async def test_send_delta_streams_by_editing_message(monkeypatch) -> None:
     times = iter([1.0, 3.0, 5.0])
     monkeypatch.setattr("nanobot.channels.discord.time.monotonic", lambda: next(times, 5.0))
 
-    await owner.send_delta("123", "hel", {"_stream_delta": True, "_stream_id": "s1"})
-    await owner.send_delta("123", "lo", {"_stream_delta": True, "_stream_id": "s1"})
-    await owner.send_delta("123", "", {"_stream_end": True, "_stream_id": "s1"})
+    await owner.send_delta("123", "hel", stream_id="s1")
+    await owner.send_delta("123", "lo", stream_id="s1")
+    await owner.send_delta("123", "", stream_id="s1", stream_end=True)
 
     assert target.sent_payloads[0] == {"content": "hel"}
     assert target.sent_messages[0].edits == [{"content": "hello"}, {"content": "hello"}]
@@ -745,9 +746,9 @@ async def test_send_delta_stream_end_splits_oversized_reply(monkeypatch) -> None
     times = iter([1.0, 3.0])
     monkeypatch.setattr("nanobot.channels.discord.time.monotonic", lambda: next(times, 3.0))
 
-    await owner.send_delta("123", prefix, {"_stream_delta": True, "_stream_id": "s1"})
-    await owner.send_delta("123", suffix, {"_stream_delta": True, "_stream_id": "s1"})
-    await owner.send_delta("123", "", {"_stream_end": True, "_stream_id": "s1"})
+    await owner.send_delta("123", prefix, stream_id="s1")
+    await owner.send_delta("123", suffix, stream_id="s1")
+    await owner.send_delta("123", "", stream_id="s1", stream_end=True)
 
     assert target.sent_payloads == [{"content": prefix}, {"content": chunks[1]}]
     assert target.sent_messages[0].edits == [{"content": chunks[0]}, {"content": chunks[0]}]
@@ -1073,7 +1074,7 @@ async def test_send_stops_typing_after_send() -> None:
             channel="discord",
             chat_id="123",
             content="progress",
-            metadata={"_progress": True},
+            event=ProgressEvent(content="progress"),
         )
     )
 

tests/channels/test_email_channel.py

@@ -6,6 +6,7 @@ from pathlib import Path
 import pytest
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.email import EmailChannel, EmailConfig
 
@@ -868,10 +869,7 @@ async def test_send_skips_progress_messages_before_smtp(monkeypatch) -> None:
             channel="email",
             chat_id="alice@example.com",
             content="",
-            metadata={
-                "_progress": True,
-                "_tool_events": [{"phase": "end", "name": "exec"}],
-            },
+            event=ProgressEvent(tool_events=[{"phase": "end", "name": "exec"}]),
         )
     )
 

tests/channels/test_feishu_reaction.py

@@ -193,7 +193,8 @@ class TestStreamEndReactionCleanup:
 
         await ch.send_delta(
             "oc_chat1", "",
-            metadata={"_stream_end": True, "message_id": "om_001"},
+            metadata={"message_id": "om_001"},
+            stream_end=True,
         )
 
         ch._remove_reaction.assert_called_once_with("om_001", "rx_42")
@@ -210,7 +211,7 @@ class TestStreamEndReactionCleanup:
 
         await ch.send_delta(
             "oc_chat1", "",
-            metadata={"_stream_end": True},
+            stream_end=True,
         )
 
         ch._remove_reaction.assert_not_called()
@@ -227,7 +228,8 @@ class TestStreamEndReactionCleanup:
 
         await ch.send_delta(
             "oc_chat1", "",
-            metadata={"_stream_end": True, "message_id": "om_001"},
+            metadata={"message_id": "om_001"},
+            stream_end=True,
         )
 
         ch._remove_reaction.assert_not_called()
@@ -242,7 +244,7 @@ class TestStreamEndReactionCleanup:
         ch._client.cardkit.v1.card.settings.return_value = MagicMock(success=MagicMock(return_value=True))
         ch._remove_reaction = AsyncMock()
 
-        await ch.send_delta("oc_chat1", "", metadata={"_stream_end": True})
+        await ch.send_delta("oc_chat1", "", stream_end=True)
 
         ch._remove_reaction.assert_not_called()
 
@@ -260,7 +262,7 @@ class TestStreamEndReactionCleanup:
 
     @pytest.mark.asyncio
     async def test_no_removal_when_resuming(self):
-        """_resuming=True means more tool-call rounds follow; reaction must persist."""
+        """resuming=True means more tool-call rounds follow; reaction must persist."""
         ch = _make_channel()
         ch.config.done_emoji = "DONE"
         ch._stream_bufs["oc_chat1"] = _FeishuStreamBuf(
@@ -274,7 +276,9 @@ class TestStreamEndReactionCleanup:
 
         await ch.send_delta(
             "oc_chat1", "",
-            metadata={"_stream_end": True, "_resuming": True, "message_id": "om_001"},
+            metadata={"message_id": "om_001"},
+            stream_end=True,
+            resuming=True,
         )
 
         ch._remove_reaction.assert_not_called()
@@ -299,19 +303,23 @@ class TestStreamEndReactionCleanup:
         # Intermediate stream end (more tool calls coming).
         await ch.send_delta(
             "oc_chat1", "",
-            metadata={"_stream_end": True, "_resuming": True, "message_id": "om_001"},
+            metadata={"message_id": "om_001"},
+            stream_end=True,
+            resuming=True,
         )
         ch._remove_reaction.assert_not_called()
         ch._add_reaction.assert_not_called()
 
-        # Re-prime the stream buffer for the final round (the previous _stream_end popped it).
+        # Re-prime the stream buffer for the final round (the previous stream end popped it).
         ch._stream_bufs["oc_chat1"] = _FeishuStreamBuf(
             text="t", card_id="card_1", sequence=5, last_edit=0.0,
         )
         # Final stream end (resuming=False): OnIt removed, done_emoji added.
         await ch.send_delta(
             "oc_chat1", "",
-            metadata={"_stream_end": True, "_resuming": False, "message_id": "om_001"},
+            metadata={"message_id": "om_001"},
+            stream_end=True,
+            resuming=False,
         )
         ch._remove_reaction.assert_called_once_with("om_001", "rx_42")
         ch._add_reaction.assert_called_once_with("om_001", "DONE")

tests/channels/test_feishu_reply.py

@@ -18,6 +18,7 @@ if not FEISHU_AVAILABLE:
     pytest.skip("Feishu dependencies not installed (lark-oapi)", allow_module_level=True)
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.feishu import FeishuChannel, FeishuConfig
 
@@ -332,7 +333,8 @@ async def test_send_skips_reply_for_progress_messages() -> None:
         channel="feishu",
         chat_id="oc_abc",
         content="thinking...",
-        metadata={"message_id": "om_001", "_progress": True},
+        event=ProgressEvent(content="thinking..."),
+        metadata={"message_id": "om_001"},
     ))
 
     channel._client.im.v1.message.create.assert_called_once()

tests/channels/test_feishu_streaming.py

@@ -6,6 +6,7 @@ from unittest.mock import MagicMock
 import pytest
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.feishu import FeishuChannel, FeishuConfig, _FeishuStreamBuf
 
@@ -272,7 +273,7 @@ class TestSendDelta:
         ch._client.cardkit.v1.card_element.content.return_value = _mock_content_response()
         ch._client.cardkit.v1.card.settings.return_value = _mock_content_response()
 
-        await ch.send_delta("oc_chat1", "", metadata={"_stream_end": True})
+        await ch.send_delta("oc_chat1", "", stream_end=True)
 
         assert "oc_chat1" not in ch._stream_bufs
         ch._client.cardkit.v1.card_element.content.assert_called_once()
@@ -289,7 +290,7 @@ class TestSendDelta:
         )
         ch._client.im.v1.message.create.return_value = _mock_send_response("om_fb")
 
-        await ch.send_delta("oc_chat1", "", metadata={"_stream_end": True})
+        await ch.send_delta("oc_chat1", "", stream_end=True)
 
         assert "oc_chat1" not in ch._stream_bufs
         ch._client.cardkit.v1.card_element.content.assert_not_called()
@@ -306,7 +307,8 @@ class TestSendDelta:
         await ch.send_delta(
             "oc_chat1",
             "",
-            metadata={"_stream_end": True, "message_id": "om_001", "chat_type": "group"},
+            metadata={"message_id": "om_001", "chat_type": "group"},
+            stream_end=True,
         )
 
         ch._client.im.v1.message.create.assert_called_once()
@@ -326,11 +328,11 @@ class TestSendDelta:
             "oc_chat1",
             "",
             metadata={
-                "_stream_end": True,
                 "message_id": "om_001",
                 "chat_type": "group",
                 "thread_id": "ot_001",
             },
+            stream_end=True,
         )
 
         ch._client.im.v1.message.reply.assert_called_once()
@@ -351,7 +353,8 @@ class TestSendDelta:
         await ch.send_delta(
             "oc_chat1",
             "",
-            metadata={"_stream_end": True, "message_id": "om_001", "chat_type": "group"},
+            metadata={"message_id": "om_001", "chat_type": "group"},
+            stream_end=True,
         )
 
         ch._client.im.v1.message.reply.assert_called_once()
@@ -369,7 +372,7 @@ class TestSendDelta:
         ch._client.cardkit.v1.card_element.content.return_value = _mock_content_response(success=False)
         ch._client.im.v1.message.create.return_value = _mock_send_response("om_fb")
 
-        await ch.send_delta("oc_chat1", "", metadata={"_stream_end": True})
+        await ch.send_delta("oc_chat1", "", stream_end=True)
 
         assert "oc_chat1" not in ch._stream_bufs
         assert ch._client.cardkit.v1.card.settings.call_count == 2
@@ -388,7 +391,7 @@ class TestSendDelta:
         ]
         ch._client.cardkit.v1.card.settings.return_value = _mock_content_response(True)
 
-        await ch.send_delta("oc_chat1", "", metadata={"_stream_end": True})
+        await ch.send_delta("oc_chat1", "", stream_end=True)
 
         assert "oc_chat1" not in ch._stream_bufs
         assert ch._client.cardkit.v1.card_element.content.call_count == 2
@@ -398,7 +401,7 @@ class TestSendDelta:
     @pytest.mark.asyncio
     async def test_stream_end_without_buf_is_noop(self):
         ch = _make_channel()
-        await ch.send_delta("oc_chat1", "", metadata={"_stream_end": True})
+        await ch.send_delta("oc_chat1", "", stream_end=True)
         ch._client.cardkit.v1.card_element.content.assert_not_called()
 
     @pytest.mark.asyncio
@@ -446,7 +449,7 @@ class TestToolHintInlineStreaming:
         msg = OutboundMessage(
             channel="feishu", chat_id="oc_chat1",
             content='web_fetch("https://example.com")',
-            metadata={"_tool_hint": True},
+            event=ProgressEvent(content='web_fetch("https://example.com")', tool_hint=True),
         )
         await ch.send(msg)
 
@@ -482,7 +485,7 @@ class TestToolHintInlineStreaming:
         msg = OutboundMessage(
             channel="feishu", chat_id="oc_chat1",
             content='read_file("path")',
-            metadata={"_tool_hint": True},
+            event=ProgressEvent(content='read_file("path")', tool_hint=True),
         )
         await ch.send(msg)
 
@@ -497,7 +500,8 @@ class TestToolHintInlineStreaming:
         msg = OutboundMessage(
             channel="feishu", chat_id="oc_chat1",
             content='read_file("path")',
-            metadata={"_tool_hint": True, "message_id": "om_001", "chat_type": "group"},
+            event=ProgressEvent(content='read_file("path")', tool_hint=True),
+            metadata={"message_id": "om_001", "chat_type": "group"},
         )
         await ch.send(msg)
 
@@ -514,8 +518,8 @@ class TestToolHintInlineStreaming:
         msg = OutboundMessage(
             channel="feishu", chat_id="oc_chat1",
             content='read_file("path")',
+            event=ProgressEvent(content='read_file("path")', tool_hint=True),
             metadata={
-                "_tool_hint": True,
                 "message_id": "om_001",
                 "chat_type": "group",
                 "thread_id": "ot_001",
@@ -538,7 +542,8 @@ class TestToolHintInlineStreaming:
         msg = OutboundMessage(
             channel="feishu", chat_id="oc_chat1",
             content='read_file("path")',
-            metadata={"_tool_hint": True, "message_id": "om_001", "chat_type": "group"},
+            event=ProgressEvent(content='read_file("path")', tool_hint=True),
+            metadata={"message_id": "om_001", "chat_type": "group"},
         )
         await ch.send(msg)
 
@@ -558,13 +563,15 @@ class TestToolHintInlineStreaming:
 
         msg1 = OutboundMessage(
             channel="feishu", chat_id="oc_chat1",
-            content='$ cd /project', metadata={"_tool_hint": True},
+            content='$ cd /project',
+            event=ProgressEvent(content='$ cd /project', tool_hint=True),
         )
         await ch.send(msg1)
 
         msg2 = OutboundMessage(
             channel="feishu", chat_id="oc_chat1",
-            content='$ git status', metadata={"_tool_hint": True},
+            content='$ git status',
+            event=ProgressEvent(content='$ git status', tool_hint=True),
         )
         await ch.send(msg2)
 
@@ -577,7 +584,7 @@ class TestToolHintInlineStreaming:
 
     @pytest.mark.asyncio
     async def test_tool_hint_preserved_on_final_stream_end(self):
-        """When final _stream_end closes the card, tool hint is kept in the final text."""
+        """When stream end closes the card, tool hint is kept in the final text."""
         ch = _make_channel()
         ch._stream_bufs["oc_chat1"] = _FeishuStreamBuf(
             text="Final content\n\n🔧 web_fetch(\"url\")\n\n",
@@ -586,7 +593,7 @@ class TestToolHintInlineStreaming:
         ch._client.cardkit.v1.card_element.content.return_value = _mock_content_response()
         ch._client.cardkit.v1.card.settings.return_value = _mock_content_response()
 
-        await ch.send_delta("oc_chat1", "", metadata={"_stream_end": True})
+        await ch.send_delta("oc_chat1", "", stream_end=True)
 
         assert "oc_chat1" not in ch._stream_bufs
         update_call = ch._client.cardkit.v1.card_element.content.call_args[0][0]
@@ -603,7 +610,8 @@ class TestToolHintInlineStreaming:
         for content in ("", "   ", "\t\n"):
             msg = OutboundMessage(
                 channel="feishu", chat_id="oc_chat1",
-                content=content, metadata={"_tool_hint": True},
+                content=content,
+                event=ProgressEvent(content=content, tool_hint=True),
             )
             await ch.send(msg)
 

tests/channels/test_feishu_tool_hint_code_block.py

@@ -1,7 +1,6 @@
 """Tests for FeishuChannel tool hint formatting."""
 
 import json
-from types import SimpleNamespace
 from unittest.mock import MagicMock, patch
 
 import pytest
@@ -18,6 +17,7 @@ if not FEISHU_AVAILABLE:
     pytest.skip("Feishu dependencies not installed (lark-oapi)", allow_module_level=True)
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.channels.feishu import FeishuChannel
 
 
@@ -51,7 +51,7 @@ async def test_tool_hint_sends_interactive_card(mock_feishu_channel):
         channel="feishu",
         chat_id="oc_123456",
         content='web_search("test query")',
-        metadata={"_tool_hint": True}
+        event=ProgressEvent(tool_hint=True),
     )
 
     with patch.object(mock_feishu_channel, '_send_message_sync') as mock_send:
@@ -72,7 +72,7 @@ async def test_tool_hint_empty_content_does_not_send(mock_feishu_channel):
         channel="feishu",
         chat_id="oc_123456",
         content="   ",  # whitespace only
-        metadata={"_tool_hint": True}
+        event=ProgressEvent(tool_hint=True),
     )
 
     with patch.object(mock_feishu_channel, '_send_message_sync') as mock_send:
@@ -107,7 +107,7 @@ async def test_tool_hint_multiple_tools_in_one_message(mock_feishu_channel):
         channel="feishu",
         chat_id="oc_123456",
         content='web_search("query"), read_file("/path/to/file")',
-        metadata={"_tool_hint": True}
+        event=ProgressEvent(tool_hint=True),
     )
 
     with patch.object(mock_feishu_channel, '_send_message_sync') as mock_send:
@@ -127,7 +127,7 @@ async def test_tool_hint_new_format_basic(mock_feishu_channel):
         channel="feishu",
         chat_id="oc_123456",
         content='read src/main.py, grep "TODO"',
-        metadata={"_tool_hint": True}
+        event=ProgressEvent(tool_hint=True),
     )
 
     with patch.object(mock_feishu_channel, '_send_message_sync') as mock_send:
@@ -146,7 +146,7 @@ async def test_tool_hint_new_format_with_comma_in_quotes(mock_feishu_channel):
         channel="feishu",
         chat_id="oc_123456",
         content='grep "hello, world", $ echo test',
-        metadata={"_tool_hint": True}
+        event=ProgressEvent(tool_hint=True),
     )
 
     with patch.object(mock_feishu_channel, '_send_message_sync') as mock_send:
@@ -165,7 +165,7 @@ async def test_tool_hint_new_format_with_folding(mock_feishu_channel):
         channel="feishu",
         chat_id="oc_123456",
         content='read path × 3, grep "pattern"',
-        metadata={"_tool_hint": True}
+        event=ProgressEvent(tool_hint=True),
     )
 
     with patch.object(mock_feishu_channel, '_send_message_sync') as mock_send:
@@ -184,7 +184,7 @@ async def test_tool_hint_new_format_mcp(mock_feishu_channel):
         channel="feishu",
         chat_id="oc_123456",
         content='4_5v::analyze_image("photo.jpg")',
-        metadata={"_tool_hint": True}
+        event=ProgressEvent(tool_hint=True),
     )
 
     with patch.object(mock_feishu_channel, '_send_message_sync') as mock_send:
@@ -202,7 +202,7 @@ async def test_tool_hint_keeps_commas_inside_arguments(mock_feishu_channel):
         channel="feishu",
         chat_id="oc_123456",
         content='web_search("foo, bar"), read_file("/path/to/file")',
-        metadata={"_tool_hint": True}
+        event=ProgressEvent(tool_hint=True),
     )
 
     with patch.object(mock_feishu_channel, '_send_message_sync') as mock_send:

tests/channels/test_matrix_channel.py

@@ -11,6 +11,7 @@ from nio import RoomSendResponse, SyncError
 
 import nanobot.channels.matrix as matrix_module
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.matrix import (
     MATRIX_HTML_FORMAT,
@@ -1522,7 +1523,7 @@ async def test_send_progress_keeps_typing_keepalive_running() -> None:
             channel="matrix",
             chat_id="!room:matrix.org",
             content="working...",
-            metadata={"_progress": True, "_progress_kind": "reasoning"},
+            event=ProgressEvent(content="working..."),
         )
     )
 
@@ -1544,7 +1545,7 @@ async def test_send_empty_content_does_not_call_room_send() -> None:
             channel="matrix",
             chat_id="!room:matrix.org",
             content="",
-            metadata={"_progress": True},
+            event=ProgressEvent(),
         )
     )
 
@@ -1563,7 +1564,7 @@ async def test_send_whitespace_only_content_does_not_call_room_send() -> None:
             channel="matrix",
             chat_id="!room:matrix.org",
             content="   \n\n  ",
-            metadata={"_progress": True},
+            event=ProgressEvent(content="   \n\n  "),
         )
     )
 
@@ -1883,7 +1884,7 @@ async def test_send_delta_stream_end_replaces_existing_message() -> None:
         last_edit=100.0,
     )
 
-    await channel.send_delta("!room:matrix.org", "", {"_stream_end": True})
+    await channel.send_delta("!room:matrix.org", "", stream_end=True)
 
     assert "!room:matrix.org" not in channel._stream_bufs
     assert client.typing_calls[-1] == ("!room:matrix.org", False, TYPING_NOTICE_TIMEOUT_MS)
@@ -1933,7 +1934,7 @@ async def test_send_delta_threaded_edit_keeps_replace_and_thread_relation(monkey
     }
     await channel.send_delta("!room:matrix.org", "Hello", metadata)
     await channel.send_delta("!room:matrix.org", " world", metadata)
-    await channel.send_delta("!room:matrix.org", "", {"_stream_end": True, **metadata})
+    await channel.send_delta("!room:matrix.org", "", metadata, stream_end=True)
 
     edit_content = client.room_send_calls[1]["content"]
     final_content = client.room_send_calls[2]["content"]
@@ -1966,7 +1967,7 @@ async def test_send_delta_stream_end_noop_when_buffer_missing() -> None:
     client = _FakeAsyncClient("", "", "", None)
     channel.client = client
 
-    await channel.send_delta("!room:matrix.org", "", {"_stream_end": True})
+    await channel.send_delta("!room:matrix.org", "", stream_end=True)
 
     assert client.room_send_calls == []
     assert client.typing_calls == []

tests/channels/test_signal_channel.py

@@ -10,6 +10,7 @@ from unittest.mock import MagicMock
 import pytest
 
 from nanobot.bus.events import InboundMessage, OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.signal import (
     SignalChannel,
@@ -1341,7 +1342,7 @@ class TestSend:
             channel="signal",
             chat_id="+19995550001",
             content="working...",
-            metadata={"_progress": True},
+            event=ProgressEvent(content="working..."),
         )
         await ch.send(msg)
         # Progress messages should NOT stop the typing indicator

tests/channels/test_telegram_channel.py

@@ -12,6 +12,7 @@ except ImportError:
     pytest.skip("Telegram dependencies not installed (python-telegram-bot)", allow_module_level=True)
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.telegram import (
     TELEGRAM_REPLY_CONTEXT_MAX_LEN,
@@ -604,7 +605,7 @@ async def test_send_delta_stream_end_raises_and_keeps_buffer_on_failure() -> Non
     channel._stream_bufs["123"] = _StreamBuf(text="hello", message_id=7, last_edit=0.0)
 
     with pytest.raises(RuntimeError, match="boom"):
-        await channel.send_delta("123", "", {"_stream_end": True})
+        await channel.send_delta("123", "", stream_end=True)
 
     assert "123" in channel._stream_bufs
 
@@ -621,7 +622,7 @@ async def test_send_delta_stream_end_treats_not_modified_as_success() -> None:
     channel._app.bot.edit_message_text = AsyncMock(side_effect=BadRequest("Message is not modified"))
     channel._stream_bufs["123"] = _StreamBuf(text="hello", message_id=7, last_edit=0.0, stream_id="s:0")
 
-    await channel.send_delta("123", "", {"_stream_end": True, "_stream_id": "s:0"})
+    await channel.send_delta("123", "", stream_id="s:0", stream_end=True)
 
     assert "123" not in channel._stream_bufs
 
@@ -642,7 +643,7 @@ async def test_send_delta_stream_end_does_not_fallback_on_network_timeout() -> N
     channel._stream_bufs["123"] = _StreamBuf(text="hello", message_id=7, last_edit=0.0)
 
     with pytest.raises(TimedOut, match="network timeout"):
-        await channel.send_delta("123", "", {"_stream_end": True})
+        await channel.send_delta("123", "", stream_end=True)
 
     # Every call to edit_message_text must have used parse_mode="HTML" —
     # no plain-text fallback call should have been made.
@@ -666,7 +667,7 @@ async def test_send_delta_stream_end_does_not_fallback_on_network_error() -> Non
     channel._stream_bufs["123"] = _StreamBuf(text="hello", message_id=7, last_edit=0.0)
 
     with pytest.raises(NetworkError, match="connection reset"):
-        await channel.send_delta("123", "", {"_stream_end": True})
+        await channel.send_delta("123", "", stream_end=True)
 
     # Every call to edit_message_text must have used parse_mode="HTML" —
     # no plain-text fallback call should have been made.
@@ -693,7 +694,7 @@ async def test_send_delta_stream_end_falls_back_on_bad_request() -> None:
     )
     channel._stream_bufs["123"] = _StreamBuf(text="hello <bad>", message_id=7, last_edit=0.0)
 
-    await channel.send_delta("123", "", {"_stream_end": True})
+    await channel.send_delta("123", "", stream_end=True)
 
     # edit_message_text should have been called twice: once for HTML, once for plain fallback
     assert channel._app.bot.edit_message_text.call_count == 2
@@ -724,7 +725,7 @@ async def test_send_delta_stream_end_splits_oversized_reply() -> None:
     oversized = "x" * (4000 + 500)
     channel._stream_bufs["123"] = _StreamBuf(text=oversized, message_id=7, last_edit=0.0)
 
-    await channel.send_delta("123", "", {"_stream_end": True})
+    await channel.send_delta("123", "", stream_end=True)
 
     channel._app.bot.edit_message_text.assert_called_once()
     edit_text = channel._app.bot.edit_message_text.call_args.kwargs.get("text", "")
@@ -762,7 +763,7 @@ async def test_send_delta_stream_end_html_expansion_does_not_overflow() -> None:
 
     channel._stream_bufs["123"] = _StreamBuf(text=markdown_text, message_id=7, last_edit=0.0)
 
-    await channel.send_delta("123", "", {"_stream_end": True})
+    await channel.send_delta("123", "", stream_end=True)
 
     channel._app.bot.edit_message_text.assert_called_once()
     edit_text = channel._app.bot.edit_message_text.call_args.kwargs.get("text", "")
@@ -789,7 +790,7 @@ async def test_send_delta_stream_end_splits_long_code_block_before_html_renderin
     raw_text = "```python\n" + ("print(\"line\")\n" * 450) + "```\nDone"
     channel._stream_bufs["123"] = _StreamBuf(text=raw_text, message_id=7, last_edit=0.0)
 
-    await channel.send_delta("123", "", {"_stream_end": True})
+    await channel.send_delta("123", "", stream_end=True)
 
     html_chunks = [
         channel._app.bot.edit_message_text.call_args.kwargs.get("text", ""),
@@ -819,7 +820,7 @@ async def test_send_delta_new_stream_id_replaces_stale_buffer() -> None:
         stream_id="old:0",
     )
 
-    await channel.send_delta("123", "world", {"_stream_delta": True, "_stream_id": "new:0"})
+    await channel.send_delta("123", "world", stream_id="new:0")
 
     buf = channel._stream_bufs["123"]
     assert buf.text == "world"
@@ -839,7 +840,7 @@ async def test_send_delta_incremental_edit_treats_not_modified_as_success() -> N
     channel._stream_bufs["123"] = _StreamBuf(text="hello", message_id=7, last_edit=0.0, stream_id="s:0")
     channel._app.bot.edit_message_text = AsyncMock(side_effect=BadRequest("Message is not modified"))
 
-    await channel.send_delta("123", "", {"_stream_delta": True, "_stream_id": "s:0"})
+    await channel.send_delta("123", "", stream_id="s:0")
 
     assert channel._stream_bufs["123"].last_edit > 0.0
 
@@ -864,7 +865,7 @@ async def test_send_delta_incremental_edit_splits_oversized_buffer() -> None:
         text=oversized, message_id=7, last_edit=0.0, stream_id="s:0"
     )
 
-    await channel.send_delta("123", "y", {"_stream_delta": True, "_stream_id": "s:0"})
+    await channel.send_delta("123", "y", stream_id="s:0")
 
     channel._app.bot.edit_message_text.assert_called_once()
     edit_text = channel._app.bot.edit_message_text.call_args.kwargs.get("text", "")
@@ -888,7 +889,8 @@ async def test_send_delta_initial_send_keeps_message_in_thread() -> None:
     await channel.send_delta(
         "123",
         "hello",
-        {"_stream_delta": True, "_stream_id": "s:0", "message_thread_id": 42},
+        {"message_thread_id": 42},
+        stream_id="s:0",
     )
 
     assert channel._app.bot.sent_messages[0]["message_thread_id"] == 42
@@ -962,7 +964,8 @@ async def test_send_progress_keeps_message_in_topic() -> None:
             channel="telegram",
             chat_id="123",
             content="hello",
-            metadata={"_progress": True, "message_thread_id": 42},
+            event=ProgressEvent(content="hello"),
+            metadata={"message_thread_id": 42},
         )
     )
 

tests/channels/test_websocket_channel.py

@@ -15,6 +15,14 @@ from websockets.exceptions import ConnectionClosed
 from websockets.frames import Close
 
 from nanobot.bus.events import OUTBOUND_META_AGENT_UI, OutboundMessage
+from nanobot.bus.outbound_events import (
+    GoalStateSyncEvent,
+    GoalStatusEvent,
+    ProgressEvent,
+    RuntimeModelUpdatedEvent,
+    SessionUpdatedEvent,
+    TurnEndEvent,
+)
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.websocket import (
     WebSocketChannel,
@@ -853,11 +861,10 @@ async def test_runtime_model_update_publisher_uses_websocket_outbound_event() ->
     assert event.channel == "websocket"
     assert event.chat_id == "*"
     assert event.content == ""
-    assert event.metadata == {
-        "_runtime_model_updated": True,
-        "model": "openai/gpt-4.1",
-        "model_preset": "fast",
-    }
+    assert event.metadata == {}
+    assert isinstance(event.event, RuntimeModelUpdatedEvent)
+    assert event.event.model == "openai/gpt-4.1"
+    assert event.event.model_preset == "fast"
 
 
 @pytest.mark.asyncio
@@ -929,11 +936,10 @@ async def test_send_progress_includes_structured_tool_events() -> None:
         channel="websocket",
         chat_id="chat-1",
         content='search "hermes"',
-        metadata={
-            "_progress": True,
-            "_tool_hint": True,
-            "webui_turn_id": "turn-1",
-            "_tool_events": [
+        event=ProgressEvent(
+            content='search "hermes"',
+            tool_hint=True,
+            tool_events=[
                 {
                     "version": 1,
                     "phase": "start",
@@ -946,6 +952,9 @@ async def test_send_progress_includes_structured_tool_events() -> None:
                     "embeds": [],
                 }
             ],
+        ),
+        metadata={
+            "webui_turn_id": "turn-1",
         },
     ))
 
@@ -981,9 +990,8 @@ async def test_send_file_edit_progress_uses_file_edit_event() -> None:
         channel="websocket",
         chat_id="chat-1",
         content="",
-        metadata={
-            "_progress": True,
-            "_file_edit_events": [
+        event=ProgressEvent(
+            file_edit_events=[
                 {
                     "version": 1,
                     "phase": "start",
@@ -996,7 +1004,7 @@ async def test_send_file_edit_progress_uses_file_edit_event() -> None:
                     "status": "editing",
                 }
             ],
-        },
+        ),
     ))
 
     payload = json.loads(mock_ws.send.await_args.args[0])
@@ -1034,7 +1042,8 @@ async def test_send_progress_includes_agent_ui_blob() -> None:
         channel="websocket",
         chat_id="chat-1",
         content="progress · panel",
-        metadata={"_progress": True, OUTBOUND_META_AGENT_UI: blob},
+        event=ProgressEvent(content="progress · panel"),
+        metadata={OUTBOUND_META_AGENT_UI: blob},
     ))
 
     payload = json.loads(mock_ws.send.await_args.args[0])
@@ -1051,7 +1060,7 @@ async def test_send_delta_removes_connection_on_connection_closed() -> None:
     mock_ws.send.side_effect = ConnectionClosed(Close(1006, ""), Close(1006, ""), True)
     channel._attach(mock_ws, "chat-1")
 
-    await channel.send_delta("chat-1", "chunk", {"_stream_delta": True, "_stream_id": "s1"})
+    await channel.send_delta("chat-1", "chunk", stream_id="s1")
 
     assert "chat-1" not in channel._subs
     assert mock_ws not in channel._conn_chats
@@ -1064,8 +1073,8 @@ async def test_send_delta_emits_delta_and_stream_end() -> None:
     mock_ws = AsyncMock()
     channel._attach(mock_ws, "chat-1")
 
-    await channel.send_delta("chat-1", "part", {"_stream_delta": True, "_stream_id": "sid"})
-    await channel.send_delta("chat-1", "", {"_stream_end": True, "_stream_id": "sid"})
+    await channel.send_delta("chat-1", "part", stream_id="sid")
+    await channel.send_delta("chat-1", "", stream_id="sid", stream_end=True)
 
     assert mock_ws.send.await_count == 2
     first = json.loads(mock_ws.send.call_args_list[0][0][0])
@@ -1090,7 +1099,8 @@ async def test_send_delta_stream_end_includes_inline_final_text() -> None:
     await channel.send_delta(
         "chat-1",
         "merged plain text",
-        {"_stream_delta": True, "_stream_end": True, "_stream_id": "sid"},
+        stream_id="sid",
+        stream_end=True,
     )
 
     mock_ws.send.assert_awaited_once()
@@ -1124,9 +1134,9 @@ async def test_send_delta_stream_end_rewrites_local_markdown_image(monkeypatch,
     mock_ws = AsyncMock()
     channel._attach(mock_ws, "chat-1")
 
-    await channel.send_delta("chat-1", "![Diagram](", {"_stream_delta": True, "_stream_id": "sid"})
-    await channel.send_delta("chat-1", "diagram.png)", {"_stream_delta": True, "_stream_id": "sid"})
-    await channel.send_delta("chat-1", "", {"_stream_end": True, "_stream_id": "sid"})
+    await channel.send_delta("chat-1", "![Diagram](", stream_id="sid")
+    await channel.send_delta("chat-1", "diagram.png)", stream_id="sid")
+    await channel.send_delta("chat-1", "", stream_id="sid", stream_end=True)
 
     assert mock_ws.send.await_count == 3
     final = json.loads(mock_ws.send.call_args_list[2][0][0])
@@ -1160,7 +1170,8 @@ async def test_send_delta_stream_end_rewrites_inline_final_text(monkeypatch, tmp
     await channel.send_delta(
         "chat-1",
         "![Diagram](diagram.png)",
-        {"_stream_delta": True, "_stream_end": True, "_stream_id": "sid"},
+        stream_id="sid",
+        stream_end=True,
     )
 
     mock_ws.send.assert_awaited_once()
@@ -1179,7 +1190,7 @@ async def test_send_reasoning_delta_emits_streaming_frame() -> None:
     await channel.send_reasoning_delta(
         "chat-1",
         "step-by-step thinking",
-        {"_reasoning_delta": True, "_stream_id": "r1"},
+        stream_id="r1",
     )
 
     mock_ws.send.assert_awaited_once()
@@ -1197,7 +1208,7 @@ async def test_send_reasoning_end_emits_close_frame() -> None:
     mock_ws = AsyncMock()
     channel._attach(mock_ws, "chat-1")
 
-    await channel.send_reasoning_end("chat-1", {"_reasoning_end": True, "_stream_id": "r1"})
+    await channel.send_reasoning_end("chat-1", stream_id="r1")
 
     payload = json.loads(mock_ws.send.await_args.args[0])
     assert payload == {"event": "reasoning_end", "chat_id": "chat-1", "stream_id": "r1"}
@@ -1205,9 +1216,7 @@ async def test_send_reasoning_end_emits_close_frame() -> None:
 
 @pytest.mark.asyncio
 async def test_send_reasoning_one_shot_expands_to_delta_plus_end() -> None:
-    """``send_reasoning`` is back-compat for hooks that haven't migrated:
-    the base implementation must produce one delta and one end so the
-    WebUI sees the same shape either way."""
+    """``send_reasoning`` produces one delta and one end."""
     bus = MagicMock()
     channel = WebSocketChannel({"enabled": True, "allowFrom": ["*"]}, bus, gateway=_basic_handler(bus))
     mock_ws = AsyncMock()
@@ -1217,7 +1226,7 @@ async def test_send_reasoning_one_shot_expands_to_delta_plus_end() -> None:
         channel="websocket",
         chat_id="chat-1",
         content="thinking",
-        metadata={"_reasoning": True},
+        event=ProgressEvent(content="thinking", reasoning=True),
     ))
 
     assert mock_ws.send.await_count == 2
@@ -1235,7 +1244,7 @@ async def test_send_reasoning_delta_drops_empty_chunks() -> None:
     mock_ws = AsyncMock()
     channel._attach(mock_ws, "chat-1")
 
-    await channel.send_reasoning_delta("chat-1", "", {"_reasoning_delta": True})
+    await channel.send_reasoning_delta("chat-1", "")
 
     mock_ws.send.assert_not_awaited()
 
@@ -1261,14 +1270,14 @@ async def test_stream_transcript_persists_without_subscribers() -> None:
         gateway=_basic_handler(bus),
     )
 
-    await channel.send_delta("chat-1", "hello", {"_stream_delta": True, "_stream_id": "s1"})
-    await channel.send_delta("chat-1", " world", {"_stream_delta": True, "_stream_id": "s1"})
-    await channel.send_delta("chat-1", "", {"_stream_end": True, "_stream_id": "s1"})
+    await channel.send_delta("chat-1", "hello", stream_id="s1")
+    await channel.send_delta("chat-1", " world", stream_id="s1")
+    await channel.send_delta("chat-1", "", stream_id="s1", stream_end=True)
     await channel.send(OutboundMessage(
         channel="websocket",
         chat_id="chat-1",
         content="",
-        metadata={"_turn_end": True, "latency_ms": 42},
+        event=TurnEndEvent(latency_ms=42),
     ))
 
     assert channel._subs == {}
@@ -1292,7 +1301,7 @@ async def test_send_turn_end_emits_turn_end_event() -> None:
         channel="websocket",
         chat_id="chat-1",
         content="",
-        metadata={"_turn_end": True},
+        event=TurnEndEvent(),
     ))
 
     assert _sent_ws_payloads(mock_ws) == [
@@ -1312,7 +1321,7 @@ async def test_send_turn_end_includes_latency_ms_when_present() -> None:
         channel="websocket",
         chat_id="chat-1",
         content="",
-        metadata={"_turn_end": True, "latency_ms": 1500},
+        event=TurnEndEvent(latency_ms=1500),
     ))
 
     assert _sent_ws_payloads(mock_ws) == [
@@ -1333,7 +1342,7 @@ async def test_send_turn_end_includes_goal_state_when_present() -> None:
         channel="websocket",
         chat_id="chat-1",
         content="",
-        metadata={"_turn_end": True, "goal_state": blob},
+        event=TurnEndEvent(goal_state=blob),
     ))
 
     assert _sent_ws_payloads(mock_ws) == [
@@ -1353,11 +1362,7 @@ async def test_send_goal_status_running_emits_event_with_started_at() -> None:
         channel="websocket",
         chat_id="chat-1",
         content="",
-        metadata={
-            "_goal_status": True,
-            "goal_status": "running",
-            "started_at": 1_700_000_000.5,
-        },
+        event=GoalStatusEvent(status="running", started_at=1_700_000_000.5),
     ))
 
     mock_ws.send.assert_awaited_once()
@@ -1381,11 +1386,7 @@ async def test_send_goal_status_idle_omits_started_at() -> None:
         channel="websocket",
         chat_id="chat-1",
         content="",
-        metadata={
-            "_goal_status": True,
-            "goal_status": "idle",
-            "goal_started_at": 99.0,
-        },
+        event=GoalStatusEvent(status="idle", started_at=99.0),
     ))
 
     mock_ws.send.assert_awaited_once()
@@ -1406,10 +1407,7 @@ async def test_send_goal_state_emits_blob_per_chat() -> None:
         channel="websocket",
         chat_id="chat-a",
         content="",
-        metadata={
-            "_goal_state_sync": True,
-            "goal_state": {"active": True, "ui_summary": "A"},
-        },
+        event=GoalStateSyncEvent(goal_state={"active": True, "ui_summary": "A"}),
     ))
 
     mock_a.send.assert_awaited_once()
@@ -1528,7 +1526,7 @@ async def test_send_session_updated_emits_session_updated_event() -> None:
         channel="websocket",
         chat_id="chat-1",
         content="",
-        metadata={"_session_updated": True},
+        event=SessionUpdatedEvent(),
     ))
 
     mock_ws.send.assert_awaited_once()
@@ -1547,7 +1545,7 @@ async def test_send_session_updated_includes_scope_when_present() -> None:
         channel="websocket",
         chat_id="chat-1",
         content="",
-        metadata={"_session_updated": True, "_session_update_scope": "metadata"},
+        event=SessionUpdatedEvent(scope="metadata"),
     ))
 
     mock_ws.send.assert_awaited_once()
@@ -1573,7 +1571,7 @@ async def test_send_delta_missing_connection_is_noop() -> None:
     bus = MagicMock()
     channel = WebSocketChannel({"enabled": True, "allowFrom": ["*"], "streaming": True}, bus, gateway=_basic_handler(bus))
     # No exception, no error — just a no-op
-    await channel.send_delta("nonexistent", "chunk", {"_stream_delta": True, "_stream_id": "s1"})
+    await channel.send_delta("nonexistent", "chunk", stream_id="s1")
     assert channel._subs == {}
 
 
@@ -2191,13 +2189,13 @@ async def test_end_to_end_server_pushes_streaming_deltas_to_client(bus: MagicMoc
 
             # Server pushes deltas directly
             await channel.send_delta(
-                chat_id, "Hello ", {"_stream_delta": True, "_stream_id": "s1"}
+                chat_id, "Hello ", stream_id="s1"
             )
             await channel.send_delta(
-                chat_id, "world", {"_stream_delta": True, "_stream_id": "s1"}
+                chat_id, "world", stream_id="s1"
             )
             await channel.send_delta(
-                chat_id, "", {"_stream_end": True, "_stream_id": "s1"}
+                chat_id, "", stream_id="s1", stream_end=True
             )
 
             delta1 = json.loads(await client.recv())
@@ -2218,7 +2216,7 @@ async def test_end_to_end_server_pushes_streaming_deltas_to_client(bus: MagicMoc
                 channel="websocket",
                 chat_id=chat_id,
                 content="",
-                metadata={"_turn_end": True},
+                event=TurnEndEvent(),
             ))
 
             turn_end = json.loads(await client.recv())

tests/channels/test_websocket_integration.py

@@ -16,6 +16,7 @@ import websockets
 from ws_test_client import WsTestClient, issue_token, issue_token_ok
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.channels.websocket import WebSocketChannel, WebSocketConfig
 from nanobot.webui.gateway_services import build_gateway_services
 
@@ -213,8 +214,7 @@ async def test_server_send_message(bus: MagicMock) -> None:
 
 @pytest.mark.asyncio
 async def test_server_send_tags_tool_hint_with_kind(bus: MagicMock) -> None:
-    """``_tool_hint`` metadata must surface as ``kind: "tool_hint"`` so WS
-    clients render breadcrumbs separately from conversational replies."""
+    """Tool-hint progress events surface as ``kind: "tool_hint"``."""
     ch = _ch(bus, 29919)
     t = asyncio.create_task(ch.start())
     await asyncio.sleep(0.3)
@@ -232,7 +232,7 @@ async def test_server_send_tags_tool_hint_with_kind(bus: MagicMock) -> None:
             await ch.send(OutboundMessage(
                 channel="websocket", chat_id=ready.chat_id,
                 content='weather("get")',
-                metadata={"_progress": True, "_tool_hint": True},
+                event=ProgressEvent(content='weather("get")', tool_hint=True),
             ))
             hint = await c.recv_message()
             assert hint.raw.get("kind") == "tool_hint"
@@ -242,7 +242,7 @@ async def test_server_send_tags_tool_hint_with_kind(bus: MagicMock) -> None:
             await ch.send(OutboundMessage(
                 channel="websocket", chat_id=ready.chat_id,
                 content="thinking…",
-                metadata={"_progress": True},
+                event=ProgressEvent(content="thinking…"),
             ))
             prog = await c.recv_message()
             assert prog.raw.get("kind") == "progress"
@@ -284,8 +284,8 @@ async def test_streaming_deltas_and_end(bus: MagicMock) -> None:
         async with WsTestClient("ws://127.0.0.1:29911/", client_id="s") as c:
             cid = (await c.recv_ready()).chat_id
             for part in ("Hello", " ", "world", "!"):
-                await ch.send_delta(cid, part, {"_stream_delta": True, "_stream_id": "s1"})
-            await ch.send_delta(cid, "", {"_stream_end": True, "_stream_id": "s1"})
+                await ch.send_delta(cid, part, stream_id="s1")
+            await ch.send_delta(cid, "", stream_id="s1", stream_end=True)
 
             msgs = await c.collect_stream()
             deltas = [m for m in msgs if m.event == "delta"]
@@ -305,12 +305,12 @@ async def test_interleaved_streams(bus: MagicMock) -> None:
     try:
         async with WsTestClient("ws://127.0.0.1:29912/", client_id="i") as c:
             cid = (await c.recv_ready()).chat_id
-            await ch.send_delta(cid, "A1", {"_stream_delta": True, "_stream_id": "sa"})
-            await ch.send_delta(cid, "B1", {"_stream_delta": True, "_stream_id": "sb"})
-            await ch.send_delta(cid, "A2", {"_stream_delta": True, "_stream_id": "sa"})
-            await ch.send_delta(cid, "", {"_stream_end": True, "_stream_id": "sa"})
-            await ch.send_delta(cid, "B2", {"_stream_delta": True, "_stream_id": "sb"})
-            await ch.send_delta(cid, "", {"_stream_end": True, "_stream_id": "sb"})
+            await ch.send_delta(cid, "A1", stream_id="sa")
+            await ch.send_delta(cid, "B1", stream_id="sb")
+            await ch.send_delta(cid, "A2", stream_id="sa")
+            await ch.send_delta(cid, "", stream_id="sa", stream_end=True)
+            await ch.send_delta(cid, "B2", stream_id="sb")
+            await ch.send_delta(cid, "", stream_id="sb", stream_end=True)
 
             msgs = await c.recv_n(6)
             sa = "".join(m.text for m in msgs if m.event == "delta" and m.stream_id == "sa")

tests/channels/test_wecom_channel.py

@@ -18,6 +18,7 @@ if not WECOM_AVAILABLE:
     pytest.skip("WeCom dependencies not installed (wecom_aibot_sdk)", allow_module_level=True)
 
 from nanobot.bus.events import OutboundMessage
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.wecom import (
     WecomChannel,
@@ -316,7 +317,7 @@ async def test_send_text_with_frame() -> None:
 
 @pytest.mark.asyncio
 async def test_send_progress_with_frame() -> None:
-    """When metadata has _progress, send uses reply_stream with finish=False."""
+    """Progress events use reply_stream with finish=False."""
     channel = WecomChannel(WecomConfig(bot_id="b", secret="s", allow_from=["*"]), MessageBus())
     client = _FakeWeComClient()
     channel._client = client
@@ -324,7 +325,12 @@ async def test_send_progress_with_frame() -> None:
     channel._chat_frames["chat1"] = _FakeFrame()
 
     await channel.send(
-        OutboundMessage(channel="wecom", chat_id="chat1", content="thinking...", metadata={"_progress": True})
+        OutboundMessage(
+            channel="wecom",
+            chat_id="chat1",
+            content="thinking...",
+            event=ProgressEvent(content="thinking..."),
+        )
     )
 
     client.reply_stream.assert_called_once()

tests/channels/test_weixin_channel.py

@@ -10,6 +10,7 @@ import httpx
 import pytest
 
 import nanobot.channels.weixin as weixin_mod
+from nanobot.bus.outbound_events import ProgressEvent
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.weixin import (
     ITEM_IMAGE,
@@ -686,7 +687,8 @@ async def test_send_progress_message_keeps_typing_indicator() -> None:
                 "chat_id": "wx-user",
                 "content": "thinking",
                 "media": [],
-                "metadata": {"_progress": True},
+                "event": ProgressEvent(content="thinking"),
+                "metadata": {},
             },
         )()
     )
@@ -1409,7 +1411,8 @@ async def test_buffer_single_tool_hint_not_sent_immediately() -> None:
                 "chat_id": "wx-user",
                 "content": "Using tool",
                 "media": [],
-                "metadata": {"_progress": True, "_tool_hint": True},
+                "event": ProgressEvent(content="Using tool", tool_hint=True),
+                "metadata": {},
             },
         )()
     )
@@ -1437,7 +1440,8 @@ async def test_buffer_multiple_tool_hints_flushed_on_final_answer() -> None:
                     "chat_id": "wx-user",
                     "content": hint,
                     "media": [],
-                    "metadata": {"_progress": True, "_tool_hint": True},
+                    "event": ProgressEvent(content=hint, tool_hint=True),
+                    "metadata": {},
                 },
             )()
         )
@@ -1482,7 +1486,8 @@ async def test_thought_progress_flushes_tool_hints() -> None:
                 "chat_id": "wx-user",
                 "content": "search 'foo'",
                 "media": [],
-                "metadata": {"_progress": True, "_tool_hint": True},
+                "event": ProgressEvent(content="search 'foo'", tool_hint=True),
+                "metadata": {},
             },
         )()
     )
@@ -1497,7 +1502,8 @@ async def test_thought_progress_flushes_tool_hints() -> None:
                 "chat_id": "wx-user",
                 "content": "Let me think...",
                 "media": [],
-                "metadata": {"_progress": True},
+                "event": ProgressEvent(content="Let me think..."),
+                "metadata": {},
             },
         )()
     )
@@ -1547,7 +1553,8 @@ async def test_reasoning_delta_does_not_flush_tool_hints() -> None:
                 "chat_id": "wx-user",
                 "content": "search 'foo'",
                 "media": [],
-                "metadata": {"_progress": True, "_tool_hint": True},
+                "event": ProgressEvent(content="search 'foo'", tool_hint=True),
+                "metadata": {},
             },
         )()
     )
@@ -1561,7 +1568,8 @@ async def test_reasoning_delta_does_not_flush_tool_hints() -> None:
                 "chat_id": "wx-user",
                 "content": "Thinking step 1...",
                 "media": [],
-                "metadata": {"_progress": True, "_reasoning_delta": True},
+                "event": ProgressEvent(content="Thinking step 1...", reasoning_delta=True),
+                "metadata": {},
             },
         )()
     )
@@ -1610,7 +1618,8 @@ async def test_empty_progress_message_does_not_flush_tool_hints() -> None:
                 "chat_id": "wx-user",
                 "content": "search 'foo'",
                 "media": [],
-                "metadata": {"_progress": True, "_tool_hint": True},
+                "event": ProgressEvent(content="search 'foo'", tool_hint=True),
+                "metadata": {},
             },
         )()
     )
@@ -1624,7 +1633,8 @@ async def test_empty_progress_message_does_not_flush_tool_hints() -> None:
                 "chat_id": "wx-user",
                 "content": "",
                 "media": [],
-                "metadata": {"_progress": True, "_tool_events": [{"phase": "end"}]},
+                "event": ProgressEvent(tool_events=[{"phase": "end"}]),
+                "metadata": {},
             },
         )()
     )
@@ -1671,7 +1681,8 @@ async def test_buffer_flush_refreshes_context_token() -> None:
                 "chat_id": "wx-user",
                 "content": "hint",
                 "media": [],
-                "metadata": {"_progress": True, "_tool_hint": True},
+                "event": ProgressEvent(content="hint", tool_hint=True),
+                "metadata": {},
             },
         )()
     )
@@ -1712,7 +1723,8 @@ async def test_buffer_flush_failure_does_not_block_final_answer() -> None:
                 "chat_id": "wx-user",
                 "content": "hint",
                 "media": [],
-                "metadata": {"_progress": True, "_tool_hint": True},
+                "event": ProgressEvent(content="hint", tool_hint=True),
+                "metadata": {},
             },
         )()
     )
@@ -1753,12 +1765,13 @@ async def test_buffer_flushed_on_stream_end() -> None:
                 "chat_id": "wx-user",
                 "content": "hint",
                 "media": [],
-                "metadata": {"_progress": True, "_tool_hint": True},
+                "event": ProgressEvent(content="hint", tool_hint=True),
+                "metadata": {},
             },
         )()
     )
 
-    await channel.send_delta("wx-user", "", {"_stream_end": True})
+    await channel.send_delta("wx-user", "", stream_end=True)
 
     channel._send_text.assert_awaited_once_with("wx-user", "hint", "ctx-1")
     assert "wx-user" not in channel._pending_tool_hints
@@ -1826,7 +1839,8 @@ async def test_send_tool_hints_false_drops_tool_hints() -> None:
                 "chat_id": "wx-user",
                 "content": "hint",
                 "media": [],
-                "metadata": {"_progress": True, "_tool_hint": True},
+                "event": ProgressEvent(content="hint", tool_hint=True),
+                "metadata": {},
             },
         )()
     )

tests/cli/test_interactive_retry_wait.py

@@ -3,6 +3,7 @@ from unittest.mock import patch
 
 import pytest
 
+from nanobot.bus.outbound_events import ProgressEvent, RetryWaitEvent
 from nanobot.cli import commands
 
 
@@ -14,7 +15,8 @@ async def test_interactive_retry_wait_is_rendered_as_progress_even_when_progress
     channels_config = SimpleNamespace(send_progress=False, send_tool_hints=False)
     msg = SimpleNamespace(
         content="Model request failed, retry in 2s (attempt 1).",
-        metadata={"_retry_wait": True},
+        event=RetryWaitEvent(content="Model request failed, retry in 2s (attempt 1)."),
+        metadata={},
     )
 
     async def fake_print(text: str, active_thinking: object | None, renderer=None) -> None:
@@ -40,7 +42,8 @@ async def test_reasoning_displayed_when_show_reasoning_enabled():
     )
     msg = SimpleNamespace(
         content="Let me think about this...",
-        metadata={"_progress": True, "_reasoning": True},
+        event=ProgressEvent(content="Let me think about this...", reasoning=True),
+        metadata={},
     )
 
     with patch("nanobot.cli.commands._print_cli_reasoning", side_effect=lambda t, th, r=None: calls.append(t)):
@@ -59,7 +62,8 @@ async def test_reasoning_delta_displayed_when_show_reasoning_enabled():
     )
     msg = SimpleNamespace(
         content="I should search first.",
-        metadata={"_progress": True, "_reasoning_delta": True},
+        event=ProgressEvent(content="I should search first.", reasoning_delta=True),
+        metadata={},
     )
 
     with patch("nanobot.cli.commands._print_cli_reasoning", side_effect=lambda t, th, r=None: calls.append(t)):
@@ -81,7 +85,8 @@ async def test_reasoning_delta_buffers_until_sentence_boundary():
         first = await commands._maybe_print_interactive_progress(
             SimpleNamespace(
                 content="The",
-                metadata={"_progress": True, "_reasoning_delta": True},
+                event=ProgressEvent(content="The", reasoning_delta=True),
+                metadata={},
             ),
             None,
             channels_config,
@@ -90,7 +95,8 @@ async def test_reasoning_delta_buffers_until_sentence_boundary():
         second = await commands._maybe_print_interactive_progress(
             SimpleNamespace(
                 content=" user asked.",
-                metadata={"_progress": True, "_reasoning_delta": True},
+                event=ProgressEvent(content=" user asked.", reasoning_delta=True),
+                metadata={},
             ),
             None,
             channels_config,
@@ -114,7 +120,8 @@ async def test_reasoning_end_flushes_buffered_delta():
         delta = await commands._maybe_print_interactive_progress(
             SimpleNamespace(
                 content="The user asked",
-                metadata={"_progress": True, "_reasoning_delta": True},
+                event=ProgressEvent(content="The user asked", reasoning_delta=True),
+                metadata={},
             ),
             None,
             channels_config,
@@ -123,7 +130,8 @@ async def test_reasoning_end_flushes_buffered_delta():
         end = await commands._maybe_print_interactive_progress(
             SimpleNamespace(
                 content="",
-                metadata={"_progress": True, "_reasoning_end": True},
+                event=ProgressEvent(reasoning_end=True),
+                metadata={},
             ),
             None,
             channels_config,
@@ -143,7 +151,8 @@ async def test_reasoning_hidden_when_show_reasoning_disabled():
     )
     msg = SimpleNamespace(
         content="Let me think about this...",
-        metadata={"_progress": True, "_reasoning": True},
+        event=ProgressEvent(content="Let me think about this...", reasoning=True),
+        metadata={},
     )
 
     with patch("nanobot.cli.commands._print_cli_reasoning") as mock_reasoning:
@@ -162,7 +171,8 @@ async def test_non_reasoning_progress_not_affected_by_show_reasoning():
     )
     msg = SimpleNamespace(
         content="working on it...",
-        metadata={"_progress": True},
+        event=ProgressEvent(content="working on it..."),
+        metadata={},
     )
 
     async def fake_print(text: str, thinking=None, renderer=None):
@@ -185,7 +195,8 @@ async def test_reasoning_shown_when_send_progress_disabled():
     )
     msg = SimpleNamespace(
         content="Let me think about this...",
-        metadata={"_progress": True, "_reasoning": True},
+        event=ProgressEvent(content="Let me think about this...", reasoning=True),
+        metadata={},
     )
 
     with patch(

tests/session/test_turn_continuation.py

@@ -49,10 +49,6 @@ async def test_maybe_continue_turn_queues_internal_message():
                 "message_id": "msg-1",
                 "origin_message_id": "msg-0",
                 "_wants_stream": True,
-                "_stream_id": "stream-1",
-                "_stream_delta": True,
-                "_stream_end": True,
-                "_resuming": True,
                 "webui": True,
             },
         ),
@@ -78,10 +74,6 @@ async def test_maybe_continue_turn_queues_internal_message():
     assert queued.metadata["message_id"] == "msg-1"
     assert queued.metadata["origin_message_id"] == "msg-0"
     assert queued.metadata["_wants_stream"] is True
-    assert "_stream_id" not in queued.metadata
-    assert "_stream_delta" not in queued.metadata
-    assert "_stream_end" not in queued.metadata
-    assert "_resuming" not in queued.metadata
     assert "Finish the migration." in queued.content
     assert ctx.all_messages == messages[:-1]
     assert ctx.final_content == ""

tests/utils/test_webui_turn_helpers.py

@@ -5,6 +5,7 @@ from unittest.mock import AsyncMock, MagicMock
 import pytest
 
 from nanobot.bus.events import InboundMessage
+from nanobot.bus.outbound_events import GoalStatusEvent
 from nanobot.session import webui_turns as wth
 
 
@@ -28,7 +29,8 @@ async def test_publish_turn_run_status_running_records_wall_clock() -> None:
     assert isinstance(t0, float)
     call = bus.publish_outbound.await_args[0][0]
     assert call.chat_id == "chat-a"
-    assert call.metadata.get("started_at") == t0
+    assert isinstance(call.event, GoalStatusEvent)
+    assert call.event.started_at == t0
 
 
 @pytest.mark.asyncio
@@ -41,7 +43,8 @@ async def test_publish_turn_run_status_reuses_explicit_wall_clock() -> None:
 
     assert wth.websocket_turn_wall_started_at("chat-a") == 1234.5
     call = bus.publish_outbound.await_args[0][0]
-    assert call.metadata.get("started_at") == 1234.5
+    assert isinstance(call.event, GoalStatusEvent)
+    assert call.event.started_at == 1234.5
 
 
 @pytest.mark.asyncio