RtoCodex

RtoCodex is an R package designed as a small, controlled testbed for understanding how GPT-5 Codex behaves when working with R projects locally and inside OpenAI’s universal container. The repository focuses on how differences in environment, toolchains, and package installation can affect compilation and testing of R packages that include native code.

Status

• R package skeleton intended for experimentation, not production.
• Initial focus: detecting compilation issues across environments.
• Future focus: accumulating small, targeted examples of environment-sensitive behavior discovered while developing with GPT-5 Codex.

Using RtoCodex locally

RtoCodex is meant to be cloned and used as a working directory rather than installed from CRAN.

# from the project root
R CMD INSTALL --preclean -l build-lib/unit .
Rscript tests/run_unit_tests.R --lib=build-lib/unit
R CMD check RtoCodex

The Makefile includes a test target that automates the install + harness invocation if you prefer make test.

Harness automation

• make fuzz-all (or Rscript scripts/run_fuzz.R --n=9999) tells the fuzz harness to cover the entire (USE_CPP20, USE_OPENMP) grid while logging under artifacts/fuzz/run_<timestamp-id>/combo/. The make matrix target now simply aliases make fuzz-all for compatibility.
• make fuzz (or Rscript scripts/run_fuzz.R) samples a handful of rows from the same deterministic grid, installs/tests them with the shared helpers, and records the results under artifacts/fuzz/run_<timestamp-id>/.
• make fuzz-once requests a single random combo. Pass ARGS="--n=8 --seed=123" with any fuzz target to control the sample size and RNG seed; artifacts always include config.rds (host profile, runtime metadata, seed) and summary.csv (matrix toggles, expected vs observed statuses, expectation_match, and log paths).
• make fuzz-clean removes build-lib/fuzz and artifacts/fuzz if you need to reclaim space or reset between fuzz campaigns.

Debug or "event" narratives

Complex or potentially problematic changes (e.g., a problem partially resolved by changes to the project but discovered due to PEBKAC) are logged under event-narratives/ (see AGENTS.md for the format); event-narratives/event_11_25_Path.md shows the current template in practice for a deliberately trivial example.