diff --git a/libs/hackbot-runtime/hackbot_runtime/codex_tracing.py b/libs/hackbot-runtime/hackbot_runtime/codex_tracing.py
new file mode 100644
index 00000000000..e55a5fb7516
--- /dev/null
+++ b/libs/hackbot-runtime/hackbot_runtime/codex_tracing.py
@@ -0,0 +1,352 @@
+"""Weave tracing for Codex SDK agents.
+
+Records turns, model requests, token usage, and tool calls in Weave.
+Uses the agent name and run ID from ``trace_agent``.
+
+Subagent activity isn't captured beyond the tool call that starts it.
+
+Requires hackbot-runtime's ``codex-sdk`` optional extra.
+"""
+
+import contextlib
+import json
+import logging
+from collections.abc import Iterator
+from datetime import datetime, timezone
+
+from openai_codex import AsyncTurnHandle, TurnHandle
+from openai_codex.generated.v2_all import (
+    AgentMessageThreadItem,
+    CollabAgentToolCallThreadItem,
+    CommandExecutionThreadItem,
+    DynamicToolCallThreadItem,
+    FileChangeThreadItem,
+    InputTextDynamicToolCallOutputContentItem,
+    ItemCompletedNotification,
+    ItemStartedNotification,
+    McpToolCallThreadItem,
+    MessagePhase,
+    ModelReroutedNotification,
+    ReasoningThreadItem,
+    TextUserInput,
+    ThreadTokenUsageUpdatedNotification,
+    TurnCompletedNotification,
+    TurnStatus,
+    UserMessageThreadItem,
+    WebSearchThreadItem,
+)
+from weave.conversation import Conversation, Message, Reasoning, Usage
+from weave.conversation.agent_context import resolve_agent_name
+from weave.conversation.types import ToolCallPart
+
+log = logging.getLogger("hackbot_runtime")
+
+# Turn spans are named this unless agent_name_override() gives the agent's name.
+DEFAULT_AGENT_NAME = "codex"
+
+TOOL_ITEMS = (
+    CollabAgentToolCallThreadItem,
+    CommandExecutionThreadItem,
+    DynamicToolCallThreadItem,
+    FileChangeThreadItem,
+    McpToolCallThreadItem,
+    WebSearchThreadItem,
+)
+
+
+def _tool_call(item) -> tuple[str, object]:
+    """The tool name and arguments to show for a tool item."""
+    if isinstance(item, CommandExecutionThreadItem):
+        return "shell", {"command": item.command, "cwd": item.cwd.root}
+    if isinstance(item, McpToolCallThreadItem):
+        return f"{item.server}.{item.tool}", item.arguments
+    if isinstance(item, DynamicToolCallThreadItem):
+        name = f"{item.namespace}.{item.tool}" if item.namespace else item.tool
+        return name, item.arguments
+    if isinstance(item, FileChangeThreadItem):
+        return "apply_patch", {"paths": [change.path for change in item.changes]}
+    if isinstance(item, WebSearchThreadItem):
+        return "web_search", {"query": item.query}
+    if isinstance(item, CollabAgentToolCallThreadItem):
+        return f"collab.{item.tool.value}", {"prompt": item.prompt, "model": item.model}
+
+
+def _tool_result(item) -> tuple[str, bool]:
+    """A completed tool item's result text, and whether the call failed."""
+    # web search items have no status
+    status = getattr(item, "status", None)
+
+    # Unsuccessful status values across Codex tool types.
+    failed = status is not None and status.value in (
+        "failed",
+        "declined",
+        "interrupted",
+    )
+    # Return the output and whether the tool failed.
+    if isinstance(item, CommandExecutionThreadItem):
+        failed = failed or item.exit_code not in (None, 0)
+        return item.aggregated_output or "", failed
+    if isinstance(item, McpToolCallThreadItem):
+        if item.error is not None:
+            return item.error.message, True
+        parts = []
+        # MCP results can include non-text content, extract the text.
+        if item.result is not None:
+            for c in item.result.content:
+                if isinstance(c, dict) and c.get("type") == "text":
+                    parts.append(c.get("text", ""))
+        return "\n".join(parts), failed
+    if isinstance(item, DynamicToolCallThreadItem):
+        parts = []
+        # Dynamic tool output can also include non-text content
+        for content in item.content_items or []:
+            if isinstance(content.root, InputTextDynamicToolCallOutputContentItem):
+                parts.append(content.root.text)
+        return "\n".join(parts), failed or item.success is False
+    if isinstance(item, FileChangeThreadItem):
+        # Combine the diffs from all changed files.
+        return "\n".join(change.diff for change in item.changes), failed
+    # Web search and collab calls have no output to show.
+    return "", failed
+
+
+class _TurnTrace:
+    """Records one turn's notifications as Weave spans."""
+
+    def __init__(self, conversation: Conversation, model: str, totals: dict):
+        self._conversation = conversation
+        self._model = model
+        # The shared dictionary of previous token totals
+        # used to avoid counting repeated updates (e.g. resent in rate limit update)
+        self._totals = totals
+        self._turn = conversation.start_turn(
+            agent_name=resolve_agent_name(DEFAULT_AGENT_NAME), model=model
+        )
+        # No model-request span is open yet.
+        self._chat = None
+        self._outputs: list[Message] = []
+        self._reasoning: list[str] = []
+        # Tool spans still waiting for completion, stored by tool-call ID
+        # since a tool's start and completion comes separately and we have
+        # to attach the result to the correct tool call
+        self._tools = {}
+        # The explicitly marked final answer
+        self._answer = None
+        # The latest assistant message without a phase label
+        # (to avoid explicitly labelled commentary messages), fallback answer
+        self._last_message = None
+        self._error = None
+
+    def __enter__(self):
+        # Enter Weave turn context so it stays active during the block.
+        self._turn.__enter__()
+        return self
+
+    def __exit__(self, *exc):
+        try:
+            self._finish()
+        except Exception:
+            log.exception("Codex trace failed to finish the turn")
+        return self._turn.__exit__(*exc)
+
+    def record(self, event) -> None:
+        """Record one notification; never lets a tracing bug break the stream."""
+        try:
+            self._record(event.payload)
+        except Exception:
+            log.exception("Codex trace failed to record %s", event.method)
+
+    # Ensure there is a model-request span for the activity being collected.
+    def _start_chat(self) -> None:
+        """Open the chat span for the model request now in progress."""
+        # multiple notifications could belong to one request, so do not open a span twice.
+        if self._chat is None:
+            self._chat = self._turn.start_llm(model=self._model, provider_name="openai")
+            self._chat.started_at = datetime.now(timezone.utc)
+
+    def _end_chat(self, usage: Usage | None = None) -> None:
+        chat = self._chat
+        self._chat = None
+        if chat is None:
+            return
+        reasoning_text = "\n".join(self._reasoning)
+        reasoning = None
+
+        if reasoning_text:
+            reasoning = Reasoning(content=reasoning_text)
+
+        with chat:
+            chat.record(
+                output_messages=self._outputs,
+                reasoning=reasoning,
+                usage=usage,
+            )
+        self._outputs = []
+        self._reasoning = []
+
+    def _record(self, payload) -> None:
+        if isinstance(payload, ItemStartedNotification):
+            item = payload.item.root
+            if isinstance(item, UserMessageThreadItem):
+                texts = []
+                for part in item.content:
+                    if isinstance(part.root, TextUserInput):
+                        texts.append(part.root.text)
+                self._turn.record(messages=[Message.user("\n".join(texts))])
+                return
+            self._start_chat()
+            if isinstance(item, TOOL_ITEMS):
+                name, arguments = _tool_call(item)
+                tool = self._turn.start_tool(
+                    name=name,
+                    arguments=json.dumps(arguments, default=str),
+                    tool_call_id=item.id,
+                )
+                tool.started_at = datetime.now(timezone.utc)
+                self._tools[item.id] = tool
+
+        elif isinstance(payload, ItemCompletedNotification):
+            item = payload.item.root
+            if isinstance(item, AgentMessageThreadItem):
+                self._start_chat()
+                self._outputs.append(Message.assistant(item.text))
+                # same rule as the SDK's TurnResult.final_response
+                if item.phase == MessagePhase.final_answer:
+                    self._answer = item.text
+                elif item.phase is None:
+                    self._last_message = item.text
+            elif isinstance(item, ReasoningThreadItem):
+                self._start_chat()
+                summary = item.summary or []
+                content = item.content or []
+
+                text = "\n".join(summary + content)
+                text = text.strip()
+
+                if text:
+                    self._reasoning.append(text)
+            elif isinstance(item, TOOL_ITEMS):
+                self._start_chat()
+                name, arguments = _tool_call(item)
+                arguments = json.dumps(arguments, default=str)
+                tool_call = ToolCallPart(
+                    id=item.id,
+                    name=name,
+                    arguments=arguments,
+                )
+                message = Message.assistant(tool_calls=[tool_call])
+                self._outputs.append(message)
+
+                tool = self._tools.pop(item.id, None)
+                if tool is not None:
+                    result, failed = _tool_result(item)
+                    with tool:
+                        # some calls only know their arguments once completed (e.g. web search)
+                        tool.arguments = arguments
+                        tool.result = result
+                        if failed:
+                            tool.record_error(RuntimeError("tool reported an error"))
+
+        elif isinstance(payload, ThreadTokenUsageUpdatedNotification):
+            thread = payload.thread_id
+            total = payload.token_usage.total.total_tokens
+            last = payload.token_usage.last
+            previous = self._totals.get(thread)
+            self._totals[thread] = total
+            # Skip context-size estimates, which have no input tokens.
+            if (previous is None or total > previous) and last.input_tokens > 0:
+                self._start_chat()
+                self._end_chat(
+                    Usage(
+                        input_tokens=last.input_tokens,
+                        cache_read_input_tokens=last.cached_input_tokens,
+                        output_tokens=last.output_tokens,
+                        reasoning_tokens=last.reasoning_output_tokens,
+                        total_tokens=last.total_tokens,
+                    )
+                )
+
+        elif isinstance(payload, ModelReroutedNotification):
+            self._model = payload.to_model
+            self._turn.record(model=payload.to_model)
+
+        elif isinstance(payload, TurnCompletedNotification):
+            turn = payload.turn
+            if turn.status != TurnStatus.completed:
+                self._error = (
+                    turn.error.message
+                    if turn.error is not None
+                    else f"turn {turn.status.value}"
+                )
+
+    def _finish(self) -> None:
+        """End the open chat and tool spans, and record the turn's outcome."""
+        self._end_chat()
+        for tool in self._tools.values():
+            with tool:
+                pass
+        self._tools.clear()
+        answer = self._answer if self._answer is not None else self._last_message
+        if answer:
+            self._turn.record(output_messages=[Message.assistant(answer)])
+        if self._error is not None:
+            self._turn.record_error(RuntimeError(self._error))
+
+
+def _conversation(thread_id: str, model: str) -> Conversation:
+    return Conversation(
+        conversation_id=thread_id,
+        agent_name=DEFAULT_AGENT_NAME,
+        model=model,
+        continue_parent_trace=True,
+    )
+
+
+@contextlib.contextmanager
+def trace_codex_turns() -> Iterator[None]:
+    """Trace every Codex turn streamed while active, sync or async.
+
+    Patches ``stream()`` on both turn handle types (``run()`` streams through
+    it), and restores them on exit.
+    """
+    # Per-thread token totals, shared by the thread's turns.
+    totals: dict[str, int] = {}
+    async_stream = AsyncTurnHandle.stream
+    sync_stream = TurnHandle.stream
+
+    async def traced_async_stream(self):
+        model = ""
+        try:
+            # The thread's model, for Weave to price the chat spans by.
+            model = (await self._codex._client.thread_read(self.thread_id)).thread.model
+        except Exception:
+            log.exception("Codex trace could not read the thread's model")
+        with (
+            _conversation(self.thread_id, model or "") as conversation,
+            _TurnTrace(conversation, model or "", totals) as trace,
+        ):
+            async for event in async_stream(self):
+                trace.record(event)
+                yield event
+
+    def traced_sync_stream(self):
+        model = ""
+        try:
+            model = self._client.thread_read(self.thread_id).thread.model
+        except Exception:
+            log.exception("Codex trace could not read the thread's model")
+        with (
+            _conversation(self.thread_id, model or "") as conversation,
+            _TurnTrace(conversation, model or "", totals) as trace,
+        ):
+            for event in sync_stream(self):
+                trace.record(event)
+                yield event
+
+    AsyncTurnHandle.stream = traced_async_stream
+    TurnHandle.stream = traced_sync_stream
+    try:
+        yield
+    finally:
+        AsyncTurnHandle.stream = async_stream
+        TurnHandle.stream = sync_stream
diff --git a/libs/hackbot-runtime/hackbot_runtime/tracing.py b/libs/hackbot-runtime/hackbot_runtime/tracing.py
index a5c101b2aab..35d1113bf77 100644
--- a/libs/hackbot-runtime/hackbot_runtime/tracing.py
+++ b/libs/hackbot-runtime/hackbot_runtime/tracing.py
@@ -13,6 +13,10 @@
 dashboard can tell the agents apart. Subagents get the parent agent's name too,
 so they don't show up as separate agents, are tagged with their own name, and
 get their token usage recorded.
+
+Weave has no Codex integration, so for Codex agents the runtime records each
+turn itself (:mod:`hackbot_runtime.codex_tracing`), with the same agent name and
+run id.
 """
 
 import contextlib
@@ -206,6 +210,18 @@ def process_with_subagent_usage(msg: Any, state: Any) -> str | None:
         otel_integration._process_message = process
 
 
+@contextlib.contextmanager
+def _trace_codex() -> Iterator[None]:
+    """Trace Codex turns, when the agent has the Codex SDK installed."""
+    try:
+        from hackbot_runtime.codex_tracing import trace_codex_turns
+    except ImportError:
+        yield
+        return
+    with trace_codex_turns():
+        yield
+
+
 @contextlib.contextmanager
 def trace_agent(entrypoint: Callable, run_id: str) -> Iterator[None]:
     """Trace the agent run, labelled with the agent's name and tagged with the run id.
@@ -221,5 +237,5 @@ def trace_agent(entrypoint: Callable, run_id: str) -> Iterator[None]:
     _tag_spans(run_id)
     agent = resolve_agent_name(entrypoint)
     log.info("Enabled Weave tracing for agent %s", agent)
-    with agent_name_override(agent), _trace_subagents_as(agent):
+    with agent_name_override(agent), _trace_subagents_as(agent), _trace_codex():
         yield