An OpenAI Codex agent calls persistent R through ducknng

This is the authored source for a precomputed vignette. The agent starts the local R adapter, receives its NNG URL, discovers methods from the endpoint’s ducknng RPC manifest, and invokes those methods through fresh DuckDB clients. The committed .Rmd preserves the result for package and pkgdown builds.

pi --model gpt-5.4 -e ./extensions/pi-ducknng/index.ts -p \
  "Using the package tools, start the R adapter and follow " \
  "its ducknng manifest. Evaluate and persist `mpg_by_cyl " \
  "<- aggregate(mpg ~ cyl, data = datasets::mtcars, FUN = " \
  "mean)`, returning the table. In a fresh call, use " \
  "`mpg_by_cyl` to return `transform(mpg_by_cyl, " \
  "delta_from_4cyl = mpg - mpg[cyl == 4])`. Close the " \
  "endpoint. Report the manifested methods, endpoint " \
  "process identity, and decoded rows, beginning with " \
  "`AGENT_VERIFIED_MTCARS_PERSISTENCE` only when both calls " \
  "and close succeed."

AGENT_VERIFIED_MTCARS_PERSISTENCE

• Endpoint URL: tcp://127.0.0.1:41205
• Endpoint process: PID 63619
• Manifested methods:
  • eval: persistent-process R eval, JSON request → Arrow response
  • close: persistent-process shutdown, JSON request → JSON response

First eval decoded rows (mpg_by_cyl): - 4, 26.663636363636364 - 6, 19.742857142857144 - 8, 15.1

Second fresh eval decoded rows (transform(...)): - 4, 26.663636363636364, 0 - 6, 19.742857142857144, -6.92077922077922 - 8, 15.1, -11.563636363636364

Close result: - closed: true

This verified that mpg_by_cyl persisted across fresh RPC calls to the same endpoint process.