feat(R04): immutable turn snapshot, typed agent events, conversation service

EPIC R04 (Team Duy) - the turn lifecycle leaves the widget.

R04-T01 domain/agents/conversation_execution_request.py
  Frozen snapshot of one turn, captured on the UI thread at submit time. The
  job closure used to read widget/workspace state from inside the worker
  thread, so a turn could run on a mix of submit-time and later state
  depending on thread timing.
R04-T02 domain/agents/agent_event.py
  13 frozen event types replacing untyped emit() dicts, with a two-way bridge
  so existing widgets keep consuming the legacy shape until EPIC R08. Adds
  TurnCompletedEvent - the end-of-turn signal the engine never had, which is
  why a cancelled turn and a failed turn look identical to the UI today.
R04-T03 application/conversations/conversation_application_service.py
  Runs a turn from a request and reports typed events. Never raises across the
  worker boundary; TurnResult.raise_if_failed() preserves the existing
  exception-based failure path. begin_turn()/execute_turn() expose the live
  message list for callers that autosave history mid-run.
R04-T04 ui/cowork_tab.py::build_job -> snapshot + service.
R04-T05 core/task_executors.py::_run_agent -> same service (was a second,
  slightly different assembly of the same call).

Caught while wiring the bridge: the first event vocabulary had no "notice"
event, so Agent Security warnings and auto-compaction notices would have been
silently swallowed. Added NoticeEvent plus a test that scans the engine sources
for emit() tags and fails when one has no typed counterpart.

New: tests/integration/ - real offscreen CoworkTab running a scripted turn end
to end (7 tests), including a characterisation of the extra provider call Agent
Security spends reviewing each request.

Suite: 225 passed, 2.74s. check_imports: PASS. All new files < 400 LOC.
2 pre-existing failures remain in test_config_security.py (EPIC R02/Team Nam).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
This commit is contained in:
2026-08-21 10:32:14 +09:00
co-authored by Claude Opus 5
parent 96bec976e7
commit a53163ebaf
11 changed files with 1663 additions and 53 deletions
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"""Domain entities for one agent turn: the request snapshot and the event
"""Domain entities for one agent turn: the request snapshot and the typed event
stream it produces (EPIC R04)."""
from .agent_event import (
AgentEvent,
AssistantDoneEvent,
ErrorEvent,
HistoryReadyEvent,
NoticeEvent,
OutputsAddedEvent,
OutputsRemovedEvent,
PlanUpdatedEvent,
ReasoningChunkEvent,
TextChunkEvent,
ToolCallFinishedEvent,
ToolCallStartedEvent,
ToolOutputEvent,
TurnCompletedEvent,
collect_text,
event_from_dict,
tool_calls,
)
from .conversation_execution_request import (
ConversationExecutionRequest,
new_turn_id,
)
__all__ = [
"ConversationExecutionRequest",
"new_turn_id",
"AgentEvent",
"TextChunkEvent",
"ReasoningChunkEvent",
"AssistantDoneEvent",
"PlanUpdatedEvent",
"ToolCallStartedEvent",
"ToolOutputEvent",
"ToolCallFinishedEvent",
"OutputsAddedEvent",
"OutputsRemovedEvent",
"NoticeEvent",
"HistoryReadyEvent",
"TurnCompletedEvent",
"ErrorEvent",
"event_from_dict",
"collect_text",
"tool_calls",
]
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"""AgentEvent - the typed event stream one agent turn produces (R04-T02).
Today the turn engine talks to its caller through untyped dicts::
emit({"type": "tool_result", "id": tc_id, "name": name,
"ok": result.get("ok", False), "output": result.get("output", "")})
and every consumer re-discovers the vocabulary by reading the producer. There
are eleven such shapes across ``core/chat_agent.py``, ``core/code_agent.py`` and
``core/task_executors.py``; a consumer that misspells ``"tool_result"`` or reads
``"result"`` instead of ``"output"`` fails silently, at runtime, only for the
tool path that triggers it.
This module makes the vocabulary explicit. Each event is a frozen dataclass, so:
* the set of possible events is enumerable (see :data:`EVENT_TYPES`);
* a field name typo is an ``AttributeError`` at the point of use, not a silently
missing chat bubble;
* an event can cross a thread boundary safely - it cannot be mutated after the
producer hands it over, which is exactly what the Qt-signal seam needs.
Bridging with the legacy dicts is deliberate and two-way: :func:`event_from_dict`
adapts what ``run_cowork`` emits today, and :meth:`AgentEvent.to_dict` renders an
event back into the legacy shape so existing widgets keep working untouched
while the presentation layer migrates screen by screen (EPIC R08).
Pure domain code: stdlib only, no Qt, no I/O.
"""
from __future__ import annotations
from dataclasses import dataclass, field
from typing import Any, Dict, List, Mapping, Optional, Sequence, Tuple
@dataclass(frozen=True)
class AgentEvent:
"""Base class for everything a turn can report.
``type`` is the legacy string tag, kept as a class attribute so the bridge
functions can round-trip an event without a separate mapping table.
"""
type: str = field(init=False, default="event")
def to_dict(self) -> Dict[str, Any]:
"""Render into the legacy ``emit()`` dict shape."""
return {"type": self.type}
# --------------------------------------------------------------------------- #
# Assistant output
# --------------------------------------------------------------------------- #
@dataclass(frozen=True)
class TextChunkEvent(AgentEvent):
"""One fragment of the visible answer, as it streams in."""
delta: str
type: str = field(init=False, default="text")
def to_dict(self) -> Dict[str, Any]:
return {"type": self.type, "delta": self.delta}
@dataclass(frozen=True)
class ReasoningChunkEvent(AgentEvent):
"""One fragment of the model's PRIVATE reasoning.
Drives the "Thinking" indicator only. Consumers must never append this to
the answer or persist it into conversation history - keeping it a distinct
type is what makes that mistake hard to make by accident.
"""
delta: str
type: str = field(init=False, default="reasoning")
def to_dict(self) -> Dict[str, Any]:
return {"type": self.type, "delta": self.delta}
@dataclass(frozen=True)
class AssistantDoneEvent(AgentEvent):
"""One assistant message finished. A turn with tool calls emits this once
per step, not once per turn - see :class:`TurnCompletedEvent`."""
content: str = ""
type: str = field(init=False, default="assistant_done")
def to_dict(self) -> Dict[str, Any]:
return {"type": self.type, "content": self.content}
# --------------------------------------------------------------------------- #
# Planning
# --------------------------------------------------------------------------- #
@dataclass(frozen=True)
class PlanUpdatedEvent(AgentEvent):
"""The agent rewrote its plan (the ``update_plan`` tool)."""
steps: Tuple[Dict[str, Any], ...] = ()
type: str = field(init=False, default="plan_set")
def to_dict(self) -> Dict[str, Any]:
return {"type": self.type, "steps": [dict(s) for s in self.steps]}
# --------------------------------------------------------------------------- #
# Tool lifecycle
# --------------------------------------------------------------------------- #
@dataclass(frozen=True)
class ToolCallStartedEvent(AgentEvent):
"""A tool call is about to run, with the preview shown to the user.
Maps the legacy ``tool_proposed`` event. "Proposed" was a misnomer: by the
time it is emitted the call is already going to run unless a permission gate
rejects it, and the gate reports that as a finished call with ``ok=False``.
"""
call_id: str
name: str
args: Dict[str, Any] = field(default_factory=dict)
preview: Optional[Dict[str, Any]] = None
type: str = field(init=False, default="tool_proposed")
def to_dict(self) -> Dict[str, Any]:
out: Dict[str, Any] = {"type": self.type, "id": self.call_id,
"name": self.name, "args": dict(self.args)}
if self.preview is not None:
out["preview"] = dict(self.preview)
return out
@dataclass(frozen=True)
class ToolOutputEvent(AgentEvent):
"""A line of live output from a running tool (command stdout, for example)."""
call_id: str
name: str
delta: str
type: str = field(init=False, default="tool_output")
def to_dict(self) -> Dict[str, Any]:
return {"type": self.type, "id": self.call_id, "name": self.name,
"delta": self.delta}
@dataclass(frozen=True)
class ToolCallFinishedEvent(AgentEvent):
"""A tool call ended, successfully or not.
``ok=False`` covers every failure mode alike - the tool raised, the sandbox
blocked it, or the user rejected it at the permission gate - because the
consumer's job is the same in all three: show the failure and let the model
react to it.
"""
call_id: str
name: str
ok: bool = False
output: str = ""
path: str = "" # file the tool wrote, when it wrote one
produced: Tuple[str, ...] = () # extra artefacts (e.g. a generator's outputs)
type: str = field(init=False, default="tool_result")
def to_dict(self) -> Dict[str, Any]:
out: Dict[str, Any] = {"type": self.type, "id": self.call_id, "name": self.name,
"ok": self.ok, "output": self.output}
if self.path:
out["path"] = self.path
if self.produced:
out["produced"] = list(self.produced)
return out
# --------------------------------------------------------------------------- #
# Output folder
# --------------------------------------------------------------------------- #
@dataclass(frozen=True)
class OutputsAddedEvent(AgentEvent):
"""Files appeared in the turn's output folder."""
paths: Tuple[str, ...] = ()
type: str = field(init=False, default="outputs_added")
def to_dict(self) -> Dict[str, Any]:
return {"type": self.type, "paths": list(self.paths)}
@dataclass(frozen=True)
class OutputsRemovedEvent(AgentEvent):
"""Files were cleaned up from the turn's output folder (intermediates)."""
paths: Tuple[str, ...] = ()
type: str = field(init=False, default="outputs_removed")
def to_dict(self) -> Dict[str, Any]:
return {"type": self.type, "paths": list(self.paths)}
@dataclass(frozen=True)
class NoticeEvent(AgentEvent):
"""A UI-visible aside that is not part of the model's answer.
Three producers today, all reachable from a normal turn:
``core/agent_security.py`` (a request or command blocked by the security
layer), ``core/context_budget.py`` (the conversation was auto-compressed)
and the attachment readers (a file that could not be processed, plus live
"reading page X/Y" progress).
``level`` selects how the UI renders it: ``"progress"`` updates the thinking
indicator in place, anything else becomes a warning bubble. Dropping these
would silently hide security warnings from the user, which is why the type
exists rather than being folded into TextChunkEvent.
"""
text: str
level: str = "info"
type: str = field(init=False, default="notice")
def to_dict(self) -> Dict[str, Any]:
return {"type": self.type, "level": self.level, "text": self.text}
@dataclass(frozen=True)
class HistoryReadyEvent(AgentEvent):
"""A history session exists for this run and can be opened."""
session_id: str
type: str = field(init=False, default="history_ready")
def to_dict(self) -> Dict[str, Any]:
return {"type": self.type, "session_id": self.session_id}
# --------------------------------------------------------------------------- #
# Turn lifecycle - emitted by the application service, not by the legacy engine
# --------------------------------------------------------------------------- #
@dataclass(frozen=True)
class TurnCompletedEvent(AgentEvent):
"""The whole turn finished: no more events will follow.
New in R04. The legacy engine has no end-of-turn signal at all, so every
consumer infers "done" from the worker thread finishing - which is why a
cancelled turn and a failed turn look identical to the UI today.
"""
content: str = ""
cancelled: bool = False
type: str = field(init=False, default="turn_completed")
def to_dict(self) -> Dict[str, Any]:
return {"type": self.type, "content": self.content, "cancelled": self.cancelled}
@dataclass(frozen=True)
class ErrorEvent(AgentEvent):
"""The turn failed. ``recoverable`` marks errors the user can act on
(pick another model, shorten the prompt) rather than a hard outage."""
message: str
recoverable: bool = False
type: str = field(init=False, default="error")
def to_dict(self) -> Dict[str, Any]:
return {"type": self.type, "message": self.message,
"recoverable": self.recoverable}
# The legacy tag -> event class map. Also the authoritative list of what a turn
# can emit, which is what makes an exhaustive consumer possible for the first time.
EVENT_TYPES: Dict[str, type] = {
"text": TextChunkEvent,
"reasoning": ReasoningChunkEvent,
"assistant_done": AssistantDoneEvent,
"plan_set": PlanUpdatedEvent,
"tool_proposed": ToolCallStartedEvent,
"tool_start": ToolCallStartedEvent,
"tool_output": ToolOutputEvent,
"tool_result": ToolCallFinishedEvent,
"outputs_added": OutputsAddedEvent,
"outputs_removed": OutputsRemovedEvent,
"notice": NoticeEvent,
"history_ready": HistoryReadyEvent,
"turn_completed": TurnCompletedEvent,
"error": ErrorEvent,
}
def event_from_dict(payload: Mapping[str, Any]) -> Optional[AgentEvent]:
"""Adapt one legacy ``emit()`` dict into a typed event.
Returns ``None`` for an unknown tag instead of raising: the legacy engine is
still being refactored and may grow an event before this module knows about
it. Dropping an unrecognised event degrades the UI by one missing bubble;
raising here would abort a turn that had otherwise succeeded.
"""
kind = str(payload.get("type", ""))
cls = EVENT_TYPES.get(kind)
if cls is None:
return None
if cls is TextChunkEvent or cls is ReasoningChunkEvent:
return cls(delta=str(payload.get("delta", "")))
if cls is AssistantDoneEvent:
return AssistantDoneEvent(content=str(payload.get("content", "")))
if cls is PlanUpdatedEvent:
return PlanUpdatedEvent(steps=tuple(payload.get("steps") or ()))
if cls is ToolCallStartedEvent:
return ToolCallStartedEvent(
call_id=str(payload.get("id", "")), name=str(payload.get("name", "")),
args=dict(payload.get("args") or {}), preview=payload.get("preview"),
)
if cls is ToolOutputEvent:
return ToolOutputEvent(call_id=str(payload.get("id", "")),
name=str(payload.get("name", "")),
delta=str(payload.get("delta", "")))
if cls is ToolCallFinishedEvent:
return ToolCallFinishedEvent(
call_id=str(payload.get("id", "")), name=str(payload.get("name", "")),
ok=bool(payload.get("ok", False)), output=str(payload.get("output", "")),
path=str(payload.get("path", "") or ""),
produced=tuple(payload.get("produced") or ()),
)
if cls is OutputsAddedEvent or cls is OutputsRemovedEvent:
return cls(paths=tuple(str(p) for p in (payload.get("paths") or ())))
if cls is NoticeEvent:
return NoticeEvent(text=str(payload.get("text", "")),
level=str(payload.get("level", "info")))
if cls is HistoryReadyEvent:
return HistoryReadyEvent(session_id=str(payload.get("session_id", "")))
if cls is TurnCompletedEvent:
return TurnCompletedEvent(content=str(payload.get("content", "")),
cancelled=bool(payload.get("cancelled", False)))
return ErrorEvent(message=str(payload.get("message", "")),
recoverable=bool(payload.get("recoverable", False)))
def collect_text(events: Sequence[AgentEvent]) -> str:
"""Join every :class:`TextChunkEvent` - the visible answer, reasoning excluded.
Provided here so no consumer has to re-derive "which events are the answer",
the question the untyped dicts made easy to get wrong.
"""
return "".join(e.delta for e in events if isinstance(e, TextChunkEvent))
def tool_calls(events: Sequence[AgentEvent]) -> List[ToolCallFinishedEvent]:
"""Every finished tool call, in order - for audit views and assertions."""
return [e for e in events if isinstance(e, ToolCallFinishedEvent)]
__all__ = [
"AgentEvent",
"TextChunkEvent",
"ReasoningChunkEvent",
"AssistantDoneEvent",
"PlanUpdatedEvent",
"ToolCallStartedEvent",
"ToolOutputEvent",
"ToolCallFinishedEvent",
"OutputsAddedEvent",
"OutputsRemovedEvent",
"NoticeEvent",
"HistoryReadyEvent",
"TurnCompletedEvent",
"ErrorEvent",
"EVENT_TYPES",
"event_from_dict",
"collect_text",
"tool_calls",
]
@@ -0,0 +1,192 @@
"""ConversationExecutionRequest - an immutable snapshot of one turn (R04-T01).
``ui/cowork_tab.py::build_job`` currently builds a closure that reads widget
state from inside the worker thread::
def job(worker):
provider = self.build_provider() # reads combo boxes
extra_tools, extra_exec = self.ctx.build_mcp_tools()
proj_ctx = project_context_text(load_project(project_id))
...
Everything that closure touches can change while the turn is running: the user
can pick another model, switch workspace, or edit the project instructions. The
turn then runs on a mixture of old and new state, and which mixture depends on
thread timing - the class of bug that reproduces once a week and never in a test.
This value object is the fix: the presentation layer captures everything a turn
needs ON THE UI THREAD, at submit time, into one frozen object. Whatever happens
to the widgets afterwards, the turn keeps running on the state the user actually
submitted.
Pure domain code: stdlib only, no Qt, no filesystem access. Paths are held as
strings, not ``Path`` objects, so the snapshot stays trivially serialisable -
which is what will let a turn be queued, replayed or logged later.
"""
from __future__ import annotations
import uuid
from dataclasses import dataclass, field, replace
from typing import Any, Dict, List, Mapping, Optional, Sequence, Tuple
# Default tool-use budget for an interactive turn, and the higher ceiling a
# run-to-completion step (a Co4E flow step) is allowed. Same numbers
# ``core.chat_agent.run_cowork`` defaults to - kept here so the policy is
# visible in the request rather than buried in a function signature.
DEFAULT_MAX_STEPS = 30
DEFAULT_COMPLETION_MAX_STEPS = 200
def new_turn_id() -> str:
"""A fresh turn id. Short and random: it only has to be unique within a
session's lifetime, and it shows up in log lines humans read."""
return uuid.uuid4().hex[:12]
@dataclass(frozen=True)
class ConversationExecutionRequest:
"""Everything one agent turn needs, captured at submit time.
Attributes:
prompt: the user's message for this turn (already assembled, including
any attachment text the UI inlined).
messages: the full conversation to send, oldest first. Held as a tuple
so the snapshot cannot be mutated after capture; use
:meth:`message_list` to get the mutable copy the engine expects.
output_dir: this turn's OWN folder. Each turn writes into an isolated
directory so parallel turns cannot clobber each other's files.
session_id: the conversation this turn belongs to.
turn_id: unique per turn, for logs and for matching events to a turn.
surface: which screen submitted it ("cowork", "co4e", "ai_edit", "task").
provider / model: what to run on, already resolved (routing included).
Empty ``model`` means "the provider's configured default".
title: conversation title, used to name generated files.
project_id / project_context: the workspace and its shared instructions,
snapshotted so a mid-turn workspace switch cannot change them.
agent_role: audit-log attribution for every tool call this turn makes.
allowed_tools: permission scope. ``None`` means "all enabled tools";
a list restricts the ADVERTISED catalogue, so a read-only step
literally cannot be offered a writing tool.
max_steps / run_to_completion / completion_max_steps: tool-use budget.
enforce_rules: run the security rulebase. Co4E sandboxed runs disable it.
confirm_commands: ask before run_command/install_package (permission gate).
metadata: free-form extras a caller wants carried along (never
interpreted here) - e.g. a scheduled task's id.
"""
prompt: str
messages: Tuple[Mapping[str, Any], ...] = ()
output_dir: str = ""
session_id: str = ""
turn_id: str = field(default_factory=new_turn_id)
surface: str = "cowork"
provider: str = ""
model: str = ""
title: str = ""
project_id: str = ""
project_context: str = ""
agent_role: str = ""
allowed_tools: Optional[Tuple[str, ...]] = None
max_steps: int = DEFAULT_MAX_STEPS
run_to_completion: bool = False
completion_max_steps: int = DEFAULT_COMPLETION_MAX_STEPS
enforce_rules: bool = True
confirm_commands: bool = False
metadata: Mapping[str, Any] = field(default_factory=dict)
# -- construction helpers ------------------------------------------- #
@classmethod
def create(cls, prompt: str, messages: Optional[Sequence[Mapping[str, Any]]] = None,
**kwargs: Any) -> "ConversationExecutionRequest":
"""Build a request from ordinary mutable inputs.
The messages list is copied element by element, so a later append by the
caller (the chat panel keeps appending to its own list) cannot reach
inside a request that is already running.
"""
snapshot = tuple(dict(m) for m in (messages or ()))
allowed = kwargs.pop("allowed_tools", None)
return cls(prompt=prompt, messages=snapshot,
allowed_tools=tuple(allowed) if allowed is not None else None,
**kwargs)
def with_messages(self, messages: Sequence[Mapping[str, Any]]
) -> "ConversationExecutionRequest":
"""A copy carrying a different message list, everything else unchanged.
Used when a caller assembles the system prompt or trims history after
building the request - it must produce a NEW snapshot rather than mutate
the one a turn may already be running on.
"""
return replace(self, messages=tuple(dict(m) for m in messages))
def with_model(self, provider: str, model: str) -> "ConversationExecutionRequest":
"""A copy pinned to another provider/model - how a routing switch is
applied without touching the user's saved settings."""
return replace(self, provider=provider, model=model)
# -- accessors ------------------------------------------------------ #
def message_list(self) -> List[Dict[str, Any]]:
"""A fresh mutable copy of the messages, for the engine to append to.
The legacy engine mutates the list it is given (it inserts the system
prompt and appends assistant/tool messages). Handing it a copy is what
keeps this snapshot immutable in practice and not just by declaration.
"""
return [dict(m) for m in self.messages]
@property
def effective_max_steps(self) -> int:
"""The tool-use ceiling actually in force for this turn."""
return self.completion_max_steps if self.run_to_completion else self.max_steps
@property
def has_output_dir(self) -> bool:
"""True when this turn may write files."""
return bool(self.output_dir)
def allows_tool(self, name: str) -> bool:
"""Whether ``name`` is inside this turn's permission scope.
``update_plan`` is always allowed: it has no side effects and drives the
Plan panel, so scoping it out would silently break the UI rather than
restrict a capability.
"""
if self.allowed_tools is None:
return True
return name == "update_plan" or name in self.allowed_tools
def describe(self) -> str:
"""Compact one-line identity for log lines."""
target = f"{self.provider}/{self.model}" if self.model else self.provider or "default"
return f"turn={self.turn_id} surface={self.surface} model={target}"
def to_dict(self) -> Dict[str, Any]:
"""JSON-safe projection, for logging a turn or persisting it for replay."""
return {
"turn_id": self.turn_id,
"session_id": self.session_id,
"surface": self.surface,
"prompt": self.prompt,
"message_count": len(self.messages),
"output_dir": self.output_dir,
"provider": self.provider,
"model": self.model,
"title": self.title,
"project_id": self.project_id,
"agent_role": self.agent_role,
"allowed_tools": list(self.allowed_tools) if self.allowed_tools is not None else None,
"max_steps": self.effective_max_steps,
"run_to_completion": self.run_to_completion,
"enforce_rules": self.enforce_rules,
"confirm_commands": self.confirm_commands,
"metadata": dict(self.metadata),
}
__all__ = [
"ConversationExecutionRequest",
"new_turn_id",
"DEFAULT_MAX_STEPS",
"DEFAULT_COMPLETION_MAX_STEPS",
]