PR #274 (just merged) introduced `\`AS \\\`rows\\\`\`` in the syntax-error
branch of _hint_for_bq_bad_request. Python doesn't recognize \\\` as an
escape sequence, so the literal backslashes survived into the JSON
`hint:` field. Analyst reading the CLI error saw:
Backtick the alias (`AS \`rows\``) or rename it ...
with visible backslashes — exactly the misleading shape this dispatcher
exists to clean up. Self-review caught it; this PR replaces the
problematic substring with plain prose ("rename the alias to a
non-reserved word (AS row_count) or backtick-quote it BQ-style
(AS `rows` with literal backticks around the identifier)") that needs
no escape gymnastics.
New regression test test_no_hint_branch_leaks_literal_backslashes pins
every dispatch branch against `\\\`` and `\\\\` substrings — pytest now
catches this class on the next regression instead of waiting for an
analyst to spot it. CHANGELOG bullet rephrased to match (the same
broken backslashes leaked into the [Unreleased] entry).
Verified: 4162 tests pass; 26 in test_api_query_guardrail.py green;
demo print of the syntax-error branch shows clean output.
1ade1300c6