Avoid appending a second FORMAT clause in client.query()

[Copilot]

Summary

client.query() unconditionally appended \nFORMAT <format> to the user-supplied SQL. This produced invalid statements when a query already carried its own FORMAT clause (e.g. SELECT 1 FORMAT CSV \nFORMAT JSON) and surfaced the server-side SHOW ROW POLICIES parser bug, which rejects a trailing FORMAT clause with a SYNTAX_ERROR when no row policies exist.

Changes

• formatQuery (packages/client-common/src/client.ts): detect an existing trailing FORMAT <Name> clause via a new hasTrailingFormatClause helper and leave the query untouched instead of appending a second clause. Detection is case-insensitive, tolerates newlines, and does not misfire on identifiers like FORMATDateTime(...) or SELECT format FROM t.
• query() JSDoc: document the FORMAT-append behavior and the SHOW ROW POLICIES limitation, recommending SELECT * FROM system.row_policies as the working alternative (the empty-result case is only fully fixable server-side, since the server rejects any trailing FORMAT there).
• Unit tests (client.test.ts): cover default JSON append, omitted format, no double-append when a clause exists, case-insensitive/newline detection, trailing-semicolon stripping, and the format-as-identifier case.
• CHANGELOG: added Bug Fixes entry.

// Before: SELECT 1 FORMAT CSV \nFORMAT JSON   (invalid)
// After:  SELECT 1 FORMAT CSV                 (untouched)
await client.query({ query: 'SELECT 1 FORMAT CSV' })

Checklist

• Unit and integration tests covering the common scenarios were added
• A human-readable description of the changes was provided to include in CHANGELOG

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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