fix(oscar): uppercase identifier in isReservedKeyword before lookup

[Aias00]

What

OscarIdentifierProcessor.isReservedKeyword looked up the identifier in the all-uppercase RESERVED_KEYWORDS set without uppercasing it first, so a lowercase or mixed-case reserved word (e.g. select, Table) returned false. Direct SPI callers (completion/metadata paths) then left reserved-keyword identifiers unquoted. The bug was masked inside quoteIdentifier (which uppercases before delegating).

Location

chat2db-community-plugins/chat2db-community-oscar/src/main/java/ai/chat2db/plugin/oscar/identifier/OscarIdentifierProcessor.java:27-30

Fix

Match the sibling idiom used by DMIdentifierProcessor, SUNDBIdentifierProcessor, and XugudbIdentifierProcessor: uppercase with Locale.ROOT and guard against null.

@Override
public boolean isReservedKeyword(String identifier, Integer majorVersion, Integer minorVersion) {
    return identifier != null && RESERVED_KEYWORDS.contains(identifier.toUpperCase(Locale.ROOT));
}

(import java.util.Locale; added.)

Verification

• Sibling implementations (DM/SUNDB/XUGUDB) use the identical expression.
• OscarIdentifierProcessorTest should still pass; a lowercase reserved word now returns true.

Fixes #2385

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Fixes Oscar dialect reserved-keyword detection so isReservedKeyword uppercases identifiers (with Locale.ROOT) before checking the all-uppercase RESERVED_KEYWORDS set, aligning behavior with other dialect processors and preventing unquoted reserved words in direct SPI call paths.

Changes:

• Add Locale import and uppercase reserved-keyword lookup in OscarIdentifierProcessor.isReservedKeyword.
• Add a null guard to avoid NPEs on direct calls.

Findings (severity order):

• chat2db-community-server/chat2db-community-plugins/chat2db-community-oscar/src/main/java/ai/chat2db/plugin/oscar/identifier/OscarIdentifierProcessor.java:29-30 — Test gap: no direct unit test for isReservedKeyword covering lowercase/mixed-case inputs and null (only quoteIdentifier is exercised).

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[openai0229]

Verified on the latest main. Reserved keyword lookup is Locale.ROOT case-insensitive and null-safe; the focused Oscar suite ran 25 tests with 0 failures.