[hoangchunghien]

Fixes #738.

Preview wraps the caller's SQL in subqueries (DESCRIBE, the LIMIT projection, the count, SUMMARIZE). Two endings broke the wrapper:

• SELECT 1 AS value -- end: the line comment swallowed the wrapper's closing parenthesis.
• SELECT 1 AS value; -- end (and ; /* end */): _stripped_sql_or_refuse only drops a semicolon at the very end of the string, so this one stayed inside the subquery.

The fix is a small _subquery_body step at the top of run_preview. It finds the terminator the way the SDK does in src/hflow/curation.py (the last token DuckDB does not classify as a comment, by UTF-8 byte offset), and ends the body on a new line when the SQL ends in a comment. SQL without a trailing comment is passed through unchanged, so the sql returned for ordinary queries is the same as before. Report, pin and saved queries are untouched: they do not wrap the SQL, and they keep the user's text as written.

Tests in packages/hflow-server/tests/test_server_curation_preview.py:

• the issue's two queries, plus ; /* end */ and a trailing newline, return the same rows and count as SELECT 1 AS value, with and without stats: true
• 'a; -- not a comment /* nor this */ tiếng Việt;' inside a string literal comes back intact
• SELECT 1 AS value; SELECT 2 -- end is still refused as not a single SELECT
• the returned sql for a query without a comment is unchanged

9 of the 11 new tests fail on main and pass with the fix; the other two (the multi-statement refusal and the unchanged sql) are guards that pass either way. uv sync --locked, ruff check --fix, ruff format and ty check are clean. The full suite has 2586 passed, 8 skipped and 1 failure, tests/test_lerobot_converter.py::test_success_label_omitted_when_source_has_no_outcome_feature, which also fails in a full run on main at 7d202bc and passes on its own. It looks order-dependent (connection has an unfinished result from execute(), DuckDB 2), not related to this change.

---

^{Need help on this PR? Tag @codesmith-bot with what you need.}

[greptile-apps]

Confidence Score: 5/5

[Low impact] The PR appears safe to merge.

Summary

Fixes preview queries that end in comments by removing a trailing statement terminator and adding a newline before wrapping the query.

• Curation previews accept SQL that ends in a comment.

_{Reviews (1) · Last reviewed commit: "fix(server): accept curation preview SQL..." · Reviewed by Greptile}

[kstonekuan]

Thanks for the fix. Ruff, ty, and the full suite pass (2,548 passed); reverting the fix fails nine regression cases. Please leave the starter pool for newcomers next time. I’d welcome a real-corpus test run and a report of what breaks or feels awkward.