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fix(tracing): prevent RecursionError in truncation of truncated previews #2857

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Bahtya wants to merge 3 commits into from
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fix(tracing): prevent RecursionError in truncation of truncated previews #2857

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a2b1218
fix(tracing): prevent RecursionError in truncation of truncated previews
Bahtya Apr 8, 2026
95620ca
fix: use sentinel key to identify truncated preview dicts
Bahtya Apr 8, 2026
f6163df
fix: validate sentinel value and preview fields for truncated detection
Bahtya Apr 8, 2026
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11 changes: 11 additions & 0 deletions src/agents/tracing/processors.py
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Original file line number Diff line number Diff line change
Expand Up @@ -283,6 +283,8 @@ def _truncate_span_field_value(self, value: Any) -> Any:

return self._truncate_json_value_for_limit(sanitized_value, max_bytes)

_TRUNCATED_PREVIEW_KEY = "__truncated_preview__"

def _truncate_json_value_for_limit(self, value: Any, max_bytes: int) -> Any:
if self._value_json_size_bytes(value) <= max_bytes:
return value
Expand All @@ -291,6 +293,14 @@ def _truncate_json_value_for_limit(self, value: Any, max_bytes: int) -> Any:
return self._truncate_string_for_json_limit(value, max_bytes)

if isinstance(value, dict):
# Avoid re-truncating our own truncated preview dicts, which
# would cause infinite recursion (the preview dict contains bool
# values that get wrapped into new preview dicts, and so on).
# Use a sentinel key to reliably identify SDK-generated previews
# without matching arbitrary user data that happens to use the
# same key names.
if self._TRUNCATED_PREVIEW_KEY in value:
return value
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@chatgpt-codex-connector chatgpt-codex-connector bot Apr 8, 2026

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P2 Badge Validate sentinel value before skipping dict truncation

Fresh evidence: the new guard now returns early for any mapping that merely contains __truncated_preview__, regardless of its value or shape. If user span data includes that key (for example {"__truncated_preview__": false, ...}) and the field exceeds _OPENAI_TRACING_MAX_FIELD_BYTES, _truncate_json_value_for_limit will return the oversized dict unchanged, which can still be rejected by tracing export limits and drop trace content. Restrict the bypass to SDK-generated preview objects (for example, require value.get(__truncated_preview__) is True plus expected preview fields).

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Comment on lines +302 to +303
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P2 Badge Restrict preview bypass to SDK-owned objects

Fresh evidence: although this guard now also checks original_type and preview, it still short-circuits on any user-supplied dict that includes "__truncated_preview__": true and those keys. If that dict also contains large extra fields and exceeds _OPENAI_TRACING_MAX_FIELD_BYTES, _truncate_json_value_for_limit returns it unchanged instead of delegating to _truncate_mapping_for_json_limit, so sanitization can still emit oversized span fields that get rejected or dropped by trace ingestion.

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return self._truncate_mapping_for_json_limit(value, max_bytes)

if isinstance(value, list):
Expand Down Expand Up @@ -356,6 +366,7 @@ def _truncated_preview(self, value: Any) -> dict[str, Any]:
preview = f"<{type_name} bytes={len(value)} truncated>"

return {
self._TRUNCATED_PREVIEW_KEY: True,
"truncated": True,
"original_type": type_name,
"preview": preview,
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