core/agent+cli: accumulate usage and show on turn end /status

ChatAgent tracks session_usage and last_turn_usage; CLI prints a quiet
token line after successful turns and includes totals in /status.

src/plyngent/agent/__init__.py

@@ -10,6 +10,7 @@ from .events import MaxRoundsEvent as MaxRoundsEvent
 from .events import TextDeltaEvent as TextDeltaEvent
 from .events import ToolCallEvent as ToolCallEvent
 from .events import ToolResultEvent as ToolResultEvent
+from .events import UsageEvent as UsageEvent
 from .loop import DEFAULT_MAX_ROUNDS as DEFAULT_MAX_ROUNDS
 from .loop import run_chat_loop as run_chat_loop
 from .tools import DangerClassifier as DangerClassifier
@@ -18,3 +19,5 @@ from .tools import ToolDefinition as ToolDefinition
 from .tools import ToolRegistry as ToolRegistry
 from .tools import schema_from_callable as schema_from_callable
 from .tools import tool as tool
+from .usage import TokenUsage as TokenUsage
+from .usage import token_usage_from_api as token_usage_from_api

src/plyngent/agent/chat.py

@@ -5,7 +5,9 @@ from typing import TYPE_CHECKING
 from plyngent.lmproto.openai_compatible.model import SystemChatMessage, UserChatMessage
 
 from .budget import DEFAULT_CONTEXT_MAX_CHARS, DEFAULT_TOOL_RESULT_MAX_CHARS
+from .events import UsageEvent
 from .loop import DEFAULT_MAX_ROUNDS, run_chat_loop
+from .usage import TokenUsage
 
 if TYPE_CHECKING:
     from collections.abc import AsyncIterator, Awaitable, Callable, Sequence
@@ -38,6 +40,8 @@ class ChatAgent:
     max_context_chars: int
     messages: list[AnyChatMessage]
     pending_retry_text: str | None
+    session_usage: TokenUsage
+    last_turn_usage: TokenUsage
 
     def __init__(
         self,
@@ -72,6 +76,8 @@ class ChatAgent:
         self.max_context_chars = max_context_chars
         self.messages = list(messages) if messages is not None else []
         self.pending_retry_text = None
+        self.session_usage = TokenUsage()
+        self.last_turn_usage = TokenUsage()
         self._ensure_system_prompt()
 
     def _ensure_system_prompt(self) -> None:
@@ -116,6 +122,7 @@ class ChatAgent:
             self.messages.append(user_msg)
 
         completed = False
+        turn_usage = TokenUsage()
         try:
             async for event in run_chat_loop(
                 self.client,
@@ -130,6 +137,9 @@ class ChatAgent:
                 parallel_tools=self.parallel_tools,
                 max_context_chars=self.max_context_chars,
             ):
+                if isinstance(event, UsageEvent):
+                    turn_usage = turn_usage.add(event.usage)
+                    self.session_usage = self.session_usage.add(event.usage)
                 yield event
             completed = True
         except BaseException:
@@ -137,6 +147,7 @@ class ChatAgent:
                 self._rollback_turn(pre_len, user_msg.content)
             raise
 
+        self.last_turn_usage = turn_usage
         for message in self.messages[pre_len:]:
             await self._persist(message)
         self.pending_retry_text = None

src/plyngent/cli/display.py

@@ -11,6 +11,7 @@ from plyngent.agent import (
     TextDeltaEvent,
     ToolCallEvent,
     ToolResultEvent,
+    UsageEvent,
 )
 from plyngent.lmproto.openai_compatible.model import AssistantFunctionToolCall
 
@@ -82,6 +83,9 @@ async def render_events(events: AsyncIterator[AgentEvent]) -> None:  # noqa: C90
                 )
             else:
                 click.secho(f"\n[max rounds reached: {event.rounds}]", fg="red")
+        elif isinstance(event, UsageEvent):
+            # Printed at end of turn as a summary; individual round usage is quiet.
+            _ = event
         else:
             # AssistantMessageEvent — text already shown via TextDeltaEvent.
             _ = event

src/plyngent/cli/repl.py

@@ -60,6 +60,8 @@ def _cmd_status(state: ReplState) -> None:
     pending_disp = "yes" if pending else "no"
     ctx_chars = estimate_messages_chars(state.agent.messages)
     ctx_budget = state.agent.max_context_chars
+    session_u = state.agent.session_usage
+    last_u = state.agent.last_turn_usage
     click.echo(
         f"provider={state.provider_name}  model={state.model}\n"
         f"session={state.session_id}  messages={len(state.agent.messages)}  "
@@ -68,6 +70,8 @@ def _cmd_status(state: ReplState) -> None:
         f"rounds={state.max_rounds}  stream={'on' if state.agent.stream else 'off'}\n"
         f"context_chars={ctx_chars}/{ctx_budget}  "
         f"tool_result_max={state.agent.max_tool_result_chars}\n"
+        f"usage_session={session_u.format_line()}\n"
+        f"usage_last_turn={last_u.format_line()}\n"
         f"workspace={state.workspace}"
     )
 

src/plyngent/cli/retry.py

@@ -88,6 +88,29 @@ async def run_cancellable[T](coro: Coroutine[object, object, T]) -> T:
                 await task
 
 
+def _echo_turn_usage(agent: ChatAgent) -> None:
+    if not agent.last_turn_usage.is_zero():
+        click.secho(f"[{agent.last_turn_usage.format_line()}]", fg="bright_black")
+
+
+async def _wait_for_retry(attempt: int, max_retries: int, wait: float) -> bool:
+    click.secho(
+        f"auto-retry {attempt}/{max_retries} in {wait:g}s "
+        f"(Ctrl+C to cancel; then /retry later)",
+        fg="yellow",
+    )
+    try:
+        ok = await sleep_cancellable(wait)
+    except KeyboardInterrupt:
+        ok = False
+    if not ok:
+        click.secho("auto-retry cancelled; use /retry to try again", fg="yellow")
+        click.echo()
+        return False
+    click.secho(f"retrying ({attempt}/{max_retries})…", fg="yellow")
+    return True
+
+
 async def run_turn_with_retries(
     agent: ChatAgent,
     *,
@@ -131,24 +154,12 @@ async def run_turn_with_retries(
                     )
                 click.echo()
                 return False
-
             wait = delays[attempt]
             attempt += 1
-            click.secho(
-                f"auto-retry {attempt}/{max_retries} in {wait:g}s "
-                f"(Ctrl+C to cancel; then /retry later)",
-                fg="yellow",
-            )
-            try:
-                ok = await sleep_cancellable(wait)
-            except KeyboardInterrupt:
-                ok = False
-            if not ok:
-                click.secho("auto-retry cancelled; use /retry to try again", fg="yellow")
-                click.echo()
+            if not await _wait_for_retry(attempt, max_retries, wait):
                 return False
-            click.secho(f"retrying ({attempt}/{max_retries})…", fg="yellow")
         else:
+            _echo_turn_usage(agent)
             return True