fix(python): reject empty fts queries

[HosniBelfeki]

Summary

This hardens Python FTS query validation by rejecting Fts objects that do not provide a non-empty query_string or match_string. Previously, empty or whitespace-only FTS values could pass Python-side validation and reach the native query path.

The executor now forwards stripped FTS text to the native _Fts object, keeping validation and execution behavior consistent.

Tests

• python -m ruff check python/zvec/model/param/query.py python/zvec/executor/query_executor.py python/tests/test_fts_query.py python/tests/test_query_executor.py
• python -m py_compile python/zvec/model/param/query.py python/zvec/executor/query_executor.py python/tests/test_fts_query.py python/tests/test_query_executor.py

Note: focused pytest against local source is blocked in this workspace because zvec._zvec is not built locally.

[Copilot]

Pull request overview

This PR hardens Python-side validation and execution for FTS (full-text search) queries by rejecting empty/whitespace-only Fts inputs and ensuring stripped FTS text is forwarded to the native _Fts binding.

Changes:

• Treat whitespace-only fts.query_string / fts.match_string as empty via centralized stripping helpers and update has_fts() accordingly.
• Add validation to reject Fts objects that provide neither a non-empty query_string nor match_string.
• Update the executor to forward stripped FTS strings to native _Fts, and add tests covering empty inputs and stripping behavior.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
python/zvec/model/param/query.py	Adds stripped/normalized FTS accessors and strengthens _validate() to reject empty FTS.
python/zvec/executor/query_executor.py	Forwards stripped FTS strings into the native _Fts query object.
python/tests/test_query_executor.py	Adds a regression test ensuring FTS text is stripped before reaching native query construction.
python/tests/test_fts_query.py	Adds parameterized tests asserting empty/whitespace-only FTS inputs are rejected.

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.

Suppressed comments (3)

python/zvec/model/param/query.py:125

• _fts_match_string() has the same issue as _fts_query_string(): calling .strip() on a non-string will raise at runtime, and could also pass an unexpected type into the native query layer. Add a runtime type check and raise ValueError with a clear message.

    def _fts_match_string(self) -> str:
        return (
            self.fts.match_string.strip() if self.fts and self.fts.match_string else ""
        )

python/zvec/model/param/query.py:120

• _fts_query_string() assumes self.fts.query_string is a str and calls .strip() unconditionally when truthy. Since dataclasses don't enforce types at runtime, passing a non-string (e.g., int/bytes) will raise AttributeError (or propagate an unexpected type into the native _Fts binding). Add an explicit runtime type check and raise a clear ValueError instead.

This issue also appears on line 122 of the same file.

    def _fts_query_string(self) -> str:
        return (
            self.fts.query_string.strip() if self.fts and self.fts.query_string else ""
        )

python/zvec/executor/query_executor.py:223

• QueryExecutor is calling Query methods that are underscore-prefixed (_fts_query_string(), _fts_match_string()), which implies they are private implementation details. Since this behavior is now relied on across modules, consider making these helpers part of the public Query API (e.g., fts_query_string() / fts_match_string() or fts_query_string_stripped properties) and update callers accordingly to avoid coupling to internals.

    def _apply_fts(self, query: Query, search_query: _SearchQuery) -> None:
        """Set FTS query on search_query if the query has FTS parameters."""
        if query.has_fts():
            fts = _Fts()
            fts.query_string = query._fts_query_string()
            fts.match_string = query._fts_match_string()