The most recent run under base, by time, and only if it finished.

WHY THIS IS NOT sort(dirs, decreasing = TRUE)[1].

Usage

latest_run_dir(
  base,
  prefix,
  require_file = NULL,
  require_pattern = NULL,
  label = "run",
  on_none = c("stop", "null")
)

Arguments

base

directory holding the run directories.

prefix

run ids must start with this ("soc_", "final_"). "" accepts every directory.

require_file

path INSIDE a run that only exists when it finished, e.g. "comparison/comparison_ranked.csv". A run without it is not a candidate, and its mtime is what "newest" is measured on. NULL accepts any directory, which is almost never what you want.

require_pattern

alternative to require_file for runs whose completion is a FAMILY of files rather than one (05c's shard logs): a regex that at least one file directly inside the run must match. "Newest" is then the newest matching file, so a run still being written wins over an old one.

label

what to call these runs in messages.

on_none

what to do when no run qualifies. "stop" (default) for a stage that cannot proceed without one; "null" for a CHECK that must report "incomplete" and carry on – 99_check_pipeline.R does that, and a stop() there would turn a diagnosis into a crash. Returning NULL is loud only if the caller tests for it; every caller that passes "null" here prints a line saying so.

Value

The run id (basename), or stop() / NULL when nothing qualifies.

Details

That expression means "last alphabetically", which equals "most recent" only while every run id is a timestamp sharing one prefix. Runs given names broke it silently: soc_0_5cm_design_spatial sorts ahead of soc_0_5cm_20260916_232318 because 'd' > '2', so "latest" started resolving to a run that had died on its first unit, and stage 04 would have refit the final model against it without a word.

It also never asked whether the run FINISHED. Stage 04 creates its output directory before its own validations run, so a failure leaves a final_<timestamp> behind that "latest" would then deploy – which is what B2's review found from the other direction.

Examples

base <- file.path(tempdir(), "runs")
for (id in c("run_a", "run_b")) {
  dir.create(file.path(base, id, "comparison"), recursive = TRUE, showWarnings = FALSE)
  writeLines("done", file.path(base, id, "comparison", "comparison_ranked.csv"))
}
Sys.setFileTime(file.path(base, "run_a", "comparison", "comparison_ranked.csv"),
                Sys.time() - 3600)
dir.create(file.path(base, "run_c"), showWarnings = FALSE)   # started, never finished
latest_run_dir(base, "run_", require_file = "comparison/comparison_ranked.csv")
#> run resolved to: run_b  (newest of 2 finished, 2026-10-21 15:48)
#>   skipped as unfinished: run_c
#> [1] "run_b"