render_readme:build_main image has no R — create_task_readme fails with "Rscript: command not found"

[r-sayar]

Summary

scripts/create_readme.sh → common/scripts/create_task_readme --input src/api fails
with Rscript: command not found. The root cause is that the published renderer image
ghcr.io/openproblems-bio/openproblems/project/render_readme:build_main contains no R
at all, so the render_readme component can't render — natively or in its own
container.

Error

[notice] Checking if Docker image is available at
  'ghcr.io/openproblems-bio/openproblems/project/render_readme:build_main'
bash: line 82: Rscript: command not found
##[error]Process completed with exit code 1.

The render_readme executable ends up running its R script on the host (native), and the
host has no R; but forcing the container wouldn't help either, because the image itself
has no R.

Evidence — the :build_main image has no R

$ docker run --rm --entrypoint bash \
    ghcr.io/openproblems-bio/openproblems/project/render_readme:build_main \
    -c 'cat /etc/os-release | head -1; which Rscript; find / -name Rscript -type f 2>/dev/null'
PRETTY_NAME="Debian GNU/Linux 13 (trixie)"
# which Rscript  -> (nothing)
# find / -name Rscript -> (nothing)

No Rscript, no /usr/bin/R*, /usr/local/bin/R*, or /opt/R/*/bin/*.

The component's own Dockerfile installs R packages via RUN Rscript -e '…'
(remotes, processx, and openproblems.utils / openproblems / openproblems.docs),
which implies the base is expected to provide R — but the published :build_main tag does
not, so the R layer appears to be missing from what's pulled.

Reproduce

In any task repo (e.g. a task_template checkout), on Linux with Docker:

scripts/create_readme.sh

Same failure on a GitHub ubuntu-latest runner (Docker preinstalled) and on a local
Docker/colima setup.

Impact

Task READMEs cannot be regenerated headlessly — neither by a developer without a local R
toolchain nor in CI. This blocks any CI workflow that calls create_task_readme.

Possible fixes

• Ensure render_readme:build_main is published with R + the required R packages
  baked in (so the container path works), and/or
• Have the executable build the full image rather than pulling an R-less base under
  the :build_main tag.