Edit tool rows now carry display_metadata.tool_result_metadata.inline_diff
(~9KB of ANSI per edit) on the live message dict. build_api_messages strips
display_kind/display_metadata/_row_id before the wire, but the local
estimator's wire shadow only dropped PERSISTENCE_ONLY_MESSAGE_FIELDS
({"timestamp"}), so estimate_messages_tokens_rough and
estimate_request_tokens_rough priced the diff: one edit row went from 32 to
2527 estimated tokens (100 edits: 3100 -> 252600). That inflates compaction
preflight, post-tool checks and turn-overflow scoring, compacts early and
breaks the prompt cache.
PERSISTENCE_ONLY_MESSAGE_FIELDS (agent/message_metadata.py) is now the single
set of local-only fields: timestamp, display_kind, display_metadata, _row_id.
build_api_messages pops exactly that set and the estimator shadow drops it,
so the two can no longer drift. The iteration-limit summary path
(_iteration_summary_api_messages) hand-builds its wire messages and stripped
timestamp but not display_*; its key set now unions the same constant, so
the inline diff never reaches the provider there either (strict gateways
reject unknown keys). The tail-budget walk (_estimate_msg_budget_tokens) is
allowlist-based and already ignored these fields.
444066b82c