diff --git a/.github/workflows/ci-template-check.yml b/.github/workflows/ci-template-check.yml
new file mode 100644
index 0000000..9c203f9
--- /dev/null
+++ b/.github/workflows/ci-template-check.yml
@@ -0,0 +1,18 @@
+# Checks if a PR makes any changes that ought to be shared via templating.
+# See the called workflow in the scitools/workflows repo for more details.
+
+name: ci-template-check
+
+on:
+  pull_request_target:  # zizmor: ignore[dangerous-triggers]
+    branches:
+      - main
+
+permissions: {}
+
+jobs:
+  prompt-share:
+    uses: scitools/workflows/.github/workflows/ci-template-check.yml@1f2141422a63321a32575ddd186e53acff12550c
+    secrets: inherit
+    with:
+      pr_number: ${{ github.event.pull_request.number }}
diff --git a/.github/workflows/ci-tests.yml b/.github/workflows/ci-tests.yml
index 0046f51..1c21504 100644
--- a/.github/workflows/ci-tests.yml
+++ b/.github/workflows/ci-tests.yml
@@ -94,11 +94,9 @@ jobs:
       - name: "Run doctests: Docs"
         if: matrix.session == 'doctests-docs'
         run: |
-          cd docs
-          pytest --doctest-glob="*.rst" --doctest-continue-on-failure
+          tools/run_doctests.py -v "./docs/**/*.rst"
 
       - name: "Run doctests: API"
         if: matrix.session == 'doctests-api'
         run: |
-          cd lib
-          pytest --doctest-modules --doctest-continue-on-failure
+          tools/run_doctests.py -v -mr ncdata
diff --git a/tools/run_doctests.py b/tools/run_doctests.py
new file mode 100755
index 0000000..f2edc20
--- /dev/null
+++ b/tools/run_doctests.py
@@ -0,0 +1,347 @@
+#!/usr/bin/env python3
+"""CLI runner interface for Python doctests.
+
+TODO this utility should be templated for easy code sharing across repos.
+"""
+
+import argparse
+import doctest
+import importlib
+from pathlib import Path
+import pkgutil
+import sys
+import traceback
+from typing import Any, Callable
+import warnings
+
+
+def list_modules_recursive(
+    module_importname: str,
+    include_private: bool = True,
+) -> list[str]:
+    """Find all the submodules of a given module, optionally omit private modules."""
+    # Identify module from its import path : N.B. fail --> return [module-path]
+    module_names = [module_importname]
+    module_path = None
+    try:
+        module = importlib.import_module(module_importname)
+        module_path = getattr(module, "__path__", None)
+    except Exception as exc:
+        print(f"\n\nIMPORT FAILED: {module_importname}\n  error: {exc}")
+
+    if module_path is not None:
+        module_names.extend(
+            sorted(
+                mod_info.name
+                for mod_info in pkgutil.walk_packages(
+                    path=module_path,
+                    prefix=f"{module_importname}.",
+                )
+            )
+        )
+        if not include_private:
+            module_names = [
+                name
+                for name in module_names
+                if not any(
+                    part.startswith("_") for part in name.split(".")[1:]
+                )
+            ]
+
+    return module_names
+
+
+def list_filepaths_recursive(
+    file_spec: str,
+) -> list[Path]:
+    """Expand a filepath string, possibly containing globs, to a list of filepaths."""
+    if not any(c in file_spec for c in "?*["):
+        found_paths = [Path(file_spec)]
+    else:
+        path = Path(file_spec).expanduser()
+        if path.is_absolute():
+            glob_root = Path(path.anchor)
+            glob_pattern = path.relative_to(glob_root)
+        else:
+            glob_root = Path.cwd()
+            glob_pattern = path
+        found_paths = sorted(glob_root.glob(str(glob_pattern)))
+
+    return [path for path in found_paths if not path.is_dir()]
+
+
+def process_options(
+    opt_str: str, paths_are_modules: bool = True
+) -> dict[str, str | int | bool]:
+    """Convert the "-o/--options" arg into a **kwargs for the doctest function call."""
+    opt_str = opt_str.replace(" ", "")  # Remove spaces -- never meaningful
+    # Split on commas, and split each one on "=" expecting a simple name=val form
+    opts_dict: dict[str, str | int | bool] = {}
+    if opt_str:  # N.B. to avoid unexpected behaviour: "".split() --> [""]
+        for setting_str in opt_str.split(","):
+            try:
+                name, val = setting_str.split("=")
+                # Detect + translate integers and booleans (only, else leave as 'str').
+                value: str | int | bool = val
+                bool_vals = {"true": True, "false": False}
+                if val.isdigit():
+                    value = int(val)
+                elif val.lower() in bool_vals:
+                    value = bool_vals[val.lower()]
+            except ValueError:
+                msg = f"Invalid option setting {setting_str!r}, expected 'name=value' only."
+                raise ValueError(msg)
+            opts_dict[name] = value
+
+    # Implement some handy defaults
+    if not paths_are_modules:
+        if not "module_relative" in opts_dict:
+            opts_dict["module_relative"] = (
+                False  # we want this OFF, by default anyway
+            )
+    if not "optionflags" in opts_dict:
+        default_flags = doctest.ELLIPSIS | doctest.NORMALIZE_WHITESPACE
+        opts_dict["optionflags"] = default_flags  # a generally useful default?
+
+    return opts_dict
+
+
+def run_doctest_paths(
+    paths: list[str] | list[Path],
+    paths_are_modules: bool = False,
+    recurse_modules: bool = False,
+    include_private_modules: bool = False,
+    exclude_fragments: list[str] = [],
+    doctest_kwargs: dict = {},
+    verbose: bool = False,
+    dry_run: bool = False,
+    stop_on_failure: bool = False,
+):
+    n_total_fails, n_total_tests, n_paths_tested = 0, 0, 0
+
+    if verbose:
+        print(
+            "RUNNING run_doctest("
+            f"paths={paths!r}"
+            f", paths_are_modules={paths_are_modules!r}"
+            f", recurse_modules={recurse_modules!r}"
+            f", include_private_modules={include_private_modules!r}"
+            f", exclude_fragments={exclude_fragments!r}"
+            f", doctest_kwargs={doctest_kwargs!r}"
+            f", verbose={verbose!r}"
+            f", dry_run={dry_run!r}"
+            f", stop_on_failure={stop_on_failure!r}"
+            ")"
+        )
+
+    if dry_run:
+        verbose = True
+
+    # For now at least, simply discard ALL warnings.
+    warnings.simplefilter("ignore")
+
+    doctest_function: Callable
+    if paths_are_modules:
+        doctest_function = doctest.testmod
+        if recurse_modules:
+            module_paths = []
+            for path in paths:
+                module_paths += list_modules_recursive(
+                    str(
+                        path
+                    ),  # for modules, 'paths' are always strings anyway
+                    include_private=include_private_modules,
+                    # exclude_fragments=exclude_fragments,
+                )
+            paths = module_paths
+    else:
+        # paths are filepaths
+        doctest_function = doctest.testfile
+        filepaths = []
+        for path in paths:
+            filepaths += list_filepaths_recursive(
+                str(path)  # , exclude_fragments=exclude_fragments
+            )
+        paths = filepaths
+
+    for path in paths:
+        # filter with excludes
+        if any(frag in str(path) for frag in exclude_fragments):
+            continue
+        if verbose:
+            print(f"\n-----\ndoctest.{doctest_function.__name__}: {path}")
+        if dry_run:
+            continue
+
+        op_fail = None
+        arg: Any  # can be a string or a 'Module' object
+        if paths_are_modules:
+            path_str = str(path)
+            try:
+                arg = importlib.import_module(path_str)
+            except Exception as exc:
+                op_fail = exc
+        else:
+            arg = path
+
+        if op_fail is None:
+            try:
+                n_fails, n_tests = doctest_function(arg, **doctest_kwargs)
+                n_total_fails += n_fails
+                n_total_tests += n_tests
+                n_paths_tested += 1
+                if n_fails:
+                    n_ok = n_tests - n_fails
+                    msg = (
+                        f"**ERRORS**\n"
+                        f"{n_ok}/{n_tests} OK, {n_fails}/{n_tests} FAILED in path: {path}"
+                    )
+                    print(msg)
+                elif verbose:
+                    print(f"{n_tests}/{n_tests} OK in path: {path}")
+            except Exception as exc:
+                op_fail = exc
+
+        if op_fail is not None:
+            n_total_fails += 1
+            print(f"\n\nERROR occurred at {path!r}: {op_fail}\n")
+            if isinstance(op_fail, doctest.UnexpectedException):
+                # E.G. this is what happens with "-o raise_on_error=True", which is
+                #  the Python call equivalent of "-o FAIL_FAST" in the doctest CLI.
+                print(f"Doctest caught exception: {op_fail}")
+                traceback.print_exception(*op_fail.exc_info)
+
+        if n_total_fails > 0 and stop_on_failure:
+            break
+
+    if verbose or n_total_fails > 0:
+        # Print a final report
+        msgs = ["", "=====", "run_doctest: FINAL REPORT"]
+        if dry_run:
+            msgs += ["(DRY RUN: no actual tests)"]
+        elif stop_on_failure and n_total_fails > 0:
+            msgs += ["(FAIL FAST: stopped at first path with errors)"]
+
+        msgs += [
+            f"    paths tested    = {n_paths_tested}",
+            f"    tests completed = {n_total_tests}",
+            f"    errors          = {n_total_fails}",
+            "",
+        ]
+        if n_total_fails > 0:
+            msgs += ["FAILED."]
+        else:
+            msgs += ["OK."]
+
+        print("\n".join(msgs))
+
+    return n_total_fails
+
+
+_help_extra_lines = """\
+Notes:
+  * file paths support glob patterns '* ? [] **'  (** to include subdirectories)
+      * N.B. use ** to include subdirectories
+      * N.B. usually requires quotes, to avoid shell expansion
+  * module paths do *not* support globs
+      * but --recurse includes all submodules
+  * \"--exclude\" patterns are a simple substring to match (not a glob/regexp)
+
+Examples:
+  $ run_doctests \"docs/**/*.rst\"                      # test all document sources
+  $ run_doctests \"docs/user*/**/*.rst\" -e detail      # skip filepaths containing key string
+  $ run_doctests -mr mymod                            # test module + all submodules
+  $ run_doctests -mr mymod.util -e maths -e fun.err   # skip module paths with substrings
+  $ run_doctests -mr mymod -o verbose=true            # make doctest print each test
+"""
+
+
+_parser = argparse.ArgumentParser(
+    prog="run_doctests",
+    description="Run doctests in docs files, or docstrings in packages.",
+    epilog=_help_extra_lines,
+    formatter_class=argparse.RawDescriptionHelpFormatter,
+)
+_parser.add_argument(
+    "-m",
+    "--module",
+    action="store_true",
+    help="paths are module paths (xx.yy.zz), instead of filepaths.",
+)
+_parser.add_argument(
+    "-r",
+    "--recurse",
+    action="store_true",
+    help="include submodules (only applies with -m).",
+)
+_parser.add_argument(
+    "-p",
+    "--publiconly",
+    action="store_true",
+    help="exclude module names beginning '_' (only applies with -m and -r)",
+)
+_parser.add_argument(
+    "-e",
+    "--exclude",
+    action="append",
+    help="exclude paths containing substring (may appear multiple times).",
+)
+_parser.add_argument(
+    "-o",
+    "--options",
+    nargs="?",
+    help=(
+        'kwargs (Python) for doctest call, e.g. "raise_on_error=True,optionflags=8".'
+    ),
+    type=str,
+    default="",
+)
+_parser.add_argument(
+    "-v",
+    "--verbose",
+    action="store_true",
+    help="show details of each operation.",
+)
+_parser.add_argument(
+    "-d",
+    "--dryrun",
+    action="store_true",
+    help="only print names of modules/files which *would* be tested.",
+)
+_parser.add_argument(
+    "-f",
+    "--stop-on-fail",
+    action="store_true",
+    help="stop at the first path with an error (else continue to test all).",
+)
+_parser.add_argument(
+    "paths",
+    nargs="*",
+    help="docs filepaths, or module paths (not both).",
+    type=str,
+    default=[],
+)
+
+
+if __name__ == "__main__":
+    args = _parser.parse_args(sys.argv[1:])
+    # Clobber sys.argv after parsing, as the doctest functions check it even when
+    #  called directly :-(
+    sys.argv = sys.argv[:1]
+
+    if not args.paths:
+        _parser.print_help()
+    else:
+        n_errs = run_doctest_paths(
+            paths=args.paths,
+            paths_are_modules=args.module,
+            recurse_modules=args.recurse,
+            include_private_modules=not args.publiconly,
+            exclude_fragments=args.exclude or [],
+            doctest_kwargs=process_options(args.options, args.module),
+            verbose=args.verbose,
+            dry_run=args.dryrun,
+            stop_on_failure=args.stop_on_fail,
+        )
+        if n_errs > 0:
+            exit(1)