Function _safe_token_compaction_split_index

src/google/adk/apps/compaction.py:334–367

Returns a split index that avoids orphaning retained tool responses. Retained events (tail of candidate events) may contain function responses. If their matching function call events are in the compacted prefix, contents assembly can fail. This method shifts the split earlier so matching func

(
    *,
    candidate_events: list[Event],
    event_retention_size: int,
)

def _safe_token_compaction_split_index(
    *,
    candidate_events: list[Event],
    event_retention_size: int,
) -> int:
  """Returns a split index that avoids orphaning retained tool responses.

  Retained events (tail of candidate events) may contain function responses.
  If their matching function call events are in the compacted prefix, contents
  assembly can fail. This method shifts the split earlier so matching function
  call events are retained together with their responses.

  Iterates backwards through candidate_events once, maintaining a running set
  of unmatched response IDs. The latest valid split point where no unmatched
  responses remain is returned.
  """
  initial_split = len(candidate_events) - event_retention_size
  if initial_split <= 0:
    return 0

  unmatched_response_ids: set[str] = set()
  best_split = 0

  for i in range(len(candidate_events) - 1, -1, -1):
    event = candidate_events[i]
    unmatched_response_ids.update(_event_function_response_ids(event))
    call_ids = _event_function_call_ids(event)
    unmatched_response_ids -= call_ids

    if not unmatched_response_ids and i <= initial_split:
      best_split = i
      break

  return best_split


async def _run_compaction_for_token_threshold_config(