diff --git a/src/evalshift_cli/hosted/trace_events.py b/src/evalshift_cli/hosted/trace_events.py
index eb42b32..e21fd3c 100644
--- a/src/evalshift_cli/hosted/trace_events.py
+++ b/src/evalshift_cli/hosted/trace_events.py
@@ -12,6 +12,11 @@
 
 Both map here onto one wire shape so the server, the database and the client
 speak a single language. Neither internal model changes.
+
+Only :func:`from_tool_trace` has a production caller (``hosted/bundle.py``): a run
+bundle's ``examples[].traces`` come from the replay's own tool-call traces.
+:func:`from_agent_trace` converts imported agent traces to the same wire shape but is
+not wired into bundling today — those traces stay local.
 """
 
 from __future__ import annotations
@@ -170,7 +175,14 @@ def from_tool_trace(trace: ToolTrace | None, *, side: str) -> dict[str, Any] | N
 
 
 def from_agent_trace(trace: AgentTrace) -> dict[str, Any] | None:
-    """Wire stream for one imported bring-your-own-agent trace.
+    """Convert an imported agent trace to bundle wire events.
+
+    Not called by ``bundle.py`` today: imported traces (``evalshift traces import``)
+    stay local in ``.evalshift/runs/<id>/traces.jsonl`` and are read only by
+    ``evaluate``, ``report.json`` and the ``diff``/``inspect``/``replay case``
+    commands. A run bundle's ``examples[].traces`` come solely from the replay's own
+    tool-call traces via :func:`from_tool_trace`. This function exists for a future
+    caller that would include imported traces in the bundle.
 
     A round begins at each ``model_call``. The counter increments on every
     ``model_call`` after the first, so events preceding any model call stay in
diff --git a/src/evalshift_cli/traces/models.py b/src/evalshift_cli/traces/models.py
index fade868..06c0a22 100644
--- a/src/evalshift_cli/traces/models.py
+++ b/src/evalshift_cli/traces/models.py
@@ -25,10 +25,13 @@ def _to_utc(value: datetime) -> datetime:
 UtcTimestamp = Annotated[AwareDatetime, AfterValidator(_to_utc)]
 """An event timestamp, offset-aware and stored in UTC.
 
-The bundle contract requires a zero offset (`BUNDLE_SPEC.md` §Validation, enforced by
-`app/runs/bundle.py`), and these events are copied into the bundle verbatim by
-`evalshift_cli.hosted.trace_events.from_agent_trace`. So the two cases are settled here, where
-the error can still name the capture file and line:
+Imported agent traces stay local: `evalshift traces import` writes them to
+`.evalshift/runs/<id>/traces.jsonl`, and only `evaluate`, `report.json` and the
+`diff`/`inspect`/`replay case` commands read them back. They are never copied into a
+hosted run bundle — `evalshift_cli.hosted.trace_events.from_agent_trace` exists for that
+purpose but has no production caller today; `bundle.py` only calls `from_tool_trace` for
+the replay's own tool-call traces. So the two cases below are settled here, for internal
+consistency and so the error can still name the capture file and line:
 
 * an offset timestamp is unambiguous and is converted;
 * a naive one is refused, because assuming UTC would silently relabel a trace recorded