- Don't truncate workflow result_json and script (low-volume, must
stay parseable)
- Replace blind string truncation on tool_calls.input_json with
structure-aware truncJson that shortens individual string values
while keeping the JSON skeleton valid
- Add raw(uuid, {offset, limit}) API for windowed access to the
original JSONL line, so truncated content can be recovered on demand
Previously the session metadata accumulator started from zero on every
reindex pass, so an incremental update would overwrite started_at and
message_count with values derived only from the new lines.
Now reads the existing session row first and merges new data on top.