Stop duplicating dvc.yaml entries for nested dirs on Windows

[Muhtasim-Munif-Fahim]

Fixes #848.

The bug

update_dvcyaml recognizes the entries it owns by testing whether a stored path starts with the dvclive directory:

dvclive_dir = os.path.relpath(live.dir, dvcyaml_dir) + "/"

but the entries themselves are written through rel_path, which normalizes to POSIX:

return str(Path(os.path.relpath(absolute_path, dvc_root_path)).as_posix())

On Windows those two disagree as soon as dir has more than one level. The prefix comes out as dvclive\subdir/ while the stored entry reads dvclive/subdir/metrics.json, so _drop_stale_dvclive_entries matches nothing, treats every existing entry as foreign, and keeps it. The new entry is then appended alongside.

A single-level dir is unaffected, because the only separator involved is the "/" that was already hardcoded — which is why #848 reports this specifically for multi-level paths.

Reproduction

Running the snippet from the issue twice on Windows:

from dvclive import Live

with Live(dir="dvclive/subdir") as live:
    live.log_metric("metric", 1)

Before:

metrics:
- dvclive/subdir/metrics.json
- dvclive/subdir/metrics.json
plots:
- dvclive/subdir/plots/metrics:
    x: step
- dvclive/subdir/plots/metrics:
    x: step

After, it matches the expected output in the issue — one entry each, replaced rather than appended.

The fix

Normalize the prefix the same way the entries are normalized:

dvclive_dir = Path(os.path.relpath(live.dir, dvcyaml_dir)).as_posix() + "/"

Tests

Adds test_make_dvcyaml_nested_dir_not_duplicated, which reruns a nested-dir Live and asserts the entries are replaced. It fails on the windows-latest leg of your matrix without this change and is a no-op on Linux and macOS, where os.path.relpath already returns POSIX separators.

Verified on Windows: the test fails before the change and passes after; tests/ excluding tests/frameworks is 232 passed.

🤖 Generated with Claude Code

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