fix(model-hf): reject rooted POSIX paths in delete on Windows too

[Virgile-pct]

On Windows, mesh-llm models delete /tmp/model.gguf answers with a message about model stems and Hugging Face refs instead of saying that filesystem paths are not supported.

Why

parse_delete_model_ref rejects paths with is_absolute() plus a few literal shapes. Windows does not consider a leading / absolute, since that needs a drive letter or a UNC prefix, so a rooted POSIX path passes the guard and falls into the Hugging Face branch.

Measured on Windows 11 by calling resolve_model_identifier directly:

input	is_absolute()	outcome
/tmp/model.gguf	false	falls through, "Expected a model stem or Hugging Face ref..."
/home/user/model.gguf	false	falls through, same
C:\models\model.gguf	true	rejected as a path
C:/models/model.gguf	true	rejected as a path
\\server\share\model.gguf	true	rejected as a path
./model.gguf	false	rejected as a path
~/model.gguf	false	rejected as a path

Wrong answer rather than a dangerous one, and only on Windows.

What this changes

A leading / is rejected outright. No model stem or Hugging Face ref starts with one on any platform, and on Unix is_absolute() already covered it, so behaviour there is unchanged.

The test grew from one input to the seven above, minus C:/models/model.gguf, which is deliberately absent: Linux has no reason to treat it as a path, so asserting it would pass on my box and fail in CI.

Measured effect, including a number that needs explaining

Full suite on Windows 11 against main at 3f4f1c35a:

	main	this branch
passed	3457	3456
failed	17	18

The count went up, so here is the whole of it. One test is fixed, models::delete_tests::resolve_model_identifier_rejects_filesystem_paths, which is the one this branch targets. Two others failed that do not fail on main:

• runtime::config_state::tests::sync::config_sync_state_apply_preserves_additive_defaults_sections
• runtime::config_state::tests::sync::config_sync_state_apply_preserves_nested_sections_and_updates_hash

Both pass 5 runs out of 5 in isolation. runtime::config_state never calls resolve_model_identifier or parse_delete_model_ref, and this branch touches one guard in model-hf plus its test. This box produces one to three intermittent failures per full run, varying between runs, and today alone it surfaced three different ones across unrelated modules.

I would rather show you the raw number with that explanation than a tidier one.

Gates

• cargo test -p model-hf: 47 passed, 0 failed.
• cargo test -p mesh-llm-host-runtime: as above.
• cargo fmt --all --check: clean.
• cargo clippy -p model-hf -p mesh-llm-host-runtime --all-targets: 8 lints, complete sorted set identical to main.
• cargo run -p xtask -- repo-consistency no-console-print: passed.
• scripts/check-env-mutation-contract.py and python -m unittest scripts.tests.test_env_mutation_contract: passed.

Summary by CodeRabbit

• Bug Fixes
  • Improved model reference validation to consistently reject filesystem paths across platforms.
  • Added coverage for Unix, Windows, network, relative, and home-directory path formats.
  • Error messages now identify the invalid path that was provided.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Advanced

Run ID: 971661bf-d556-4a39-9604-ae74cbf4eebe

📥 Commits

Reviewing files that changed from the base of the PR and between 3f4f1c3 and b1fa3cb.

📒 Files selected for processing (2)

• crates/mesh-llm-host-runtime/src/models/delete_tests.rs
• crates/model-hf/src/store/delete.rs

Included review availability: Your plan provides up to 8 included reviews per hour; 7 remain after this review.

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📝 Walkthrough

Walkthrough

The delete model reference parser now rejects POSIX-rooted inputs in addition to absolute paths. Tests cover Unix, Windows, UNC, relative, and tilde-based filesystem path shapes.

Changes

Delete Path Validation

Layer / File(s)	Summary
Path rejection and validation crates/model-hf/src/store/delete.rs, crates/mesh-llm-host-runtime/src/models/delete_tests.rs	parse_delete_model_ref rejects inputs beginning with /. The test checks seven filesystem path shapes against the filesystem-path error and reports the failing input.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Bug fix

Suggested reviewers: ndizazzo

Merge Risk: ⚪ Minimal · up to fa337

Delete-reference validation now rejects the additional rooted path forms, with matching coverage; no merge-blocking risk is identified.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: rejecting rooted POSIX paths in model deletion on Windows.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/windows-delete-path-guard

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[i386]

Reviewed the synchronized exact head. The Windows deletion guard covers leading-slash rooted paths and preserves valid relative paths; model-hf and full host-runtime package suites pass locally.