`datad`'s persistent feed task already owns each series writer.
The actor-local and file locks duplicated this SC contract and left
`.parquet.lock` sidecars that upstream indexed as data.
- preserve validated temp writes, `fsync()`, and atomic replacement
- keep exact-suffix indexing for legacy lock and temp sidecars
- prove full and incremental writes create no lock artifacts
Prompt-IO: ai/prompt-io/opencode/20260727T204711Z_84a6d47b_prompt_io.md
(this patch was generated in some part by `opencode` using `gpt-5.6-sol` (`openai`))
