[YPARK]

What

• background on every MCP tool that writes a backend (qc with out, import, subset, subsample, split, convert, merge). The step runs as a legume-mcp 0.3 job and the call returns {job, written, note} at once. Merge also returns batches and qc returns report. legume-mcp's job_status / job_wait / job_cancel follow the job, which is recorded in runall.sh and INDEX.tsv when it ends.
• Outputs being written are claimed while the call runs, or, for a job, for as long as the server runs. Two unnamed jobs take two names, and a named output a job is writing is refused.
• Background edge cases:
  • a subset's names file is kept for its job;
  • import checks its input exists before noting provenance;
  • qc refuses background on a dry run.
• data-beans mcp watch: o opens a job's output once it exists.
• legume-mcp 0.3 (it skips 0.2). Version 0.10.1: background is an MCP tool argument, not a CLI flag, subcommand or library API, so a patch.
• README: the instructions block, the job tools, and how background writes behave.

Checks

• tests/mcp_server.rs, a_write_in_the_background_returns_a_job_that_writes_it, covers:

  • subset by pattern and by names;
  • split;
  • two unnamed jobs at once;
  • a named output a job holds;
  • the steps in runall.sh;
  • the refused dry run and missing import.

  It fails with the names-file fix reverted, and with the claim's check removed.

• cargo test --features sim, cargo fmt, and cargo clippy --all-targets --features sim: all clean.