Add input validation for Raw FTS query mode to prevent expensive or
malformed queries from reaching SQLite FTS5:
- Reject unbalanced double quotes (would cause FTS5 syntax error)
- Reject leading wildcard-only queries ("*", "* OR ...") that trigger
expensive full-table scans
- Reject empty/whitespace-only queries
- Invalid raw input falls back to Safe mode automatically instead of
erroring, so callers never see FTS5 parse failures
The Safe mode already escapes all tokens with double-quote wrapping
and handles embedded quotes via doubling. Raw mode now has a
validation layer on top.
All queries remain parameterized (?1, ?2) — user input never enters
SQL strings directly.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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