feat(spi): add quoteIdentifierAlways to ISQLIdentifierProcessor

[Aias00]

Summary

Addresses the maintainer review on #2187 requesting the shared SPI contract be extended before rebasing the individual dialect quoting PRs.

Adds quoteIdentifierAlways(String) to ISQLIdentifierProcessor — an unconditional quoting method that preserves the exact identifier name regardless of case or keyword status. Embedded delimiter characters are escaped per the dialect convention. Also fixes removeIdentifierQuote to unescape doubled delimiters, satisfying the round-trip contract: removeIdentifierQuote(quoteIdentifierAlways(raw)).equals(raw).

Changes

SPI Interface (ISQLIdentifierProcessor)

• New method quoteIdentifierAlways(String) — always quotes, preserves exact case, escapes embedded delimiters

Default Implementation (DefaultSQLIdentifierProcessor)

• quoteIdentifierAlways: wraps in "...", escapes " → ""
• removeIdentifierQuote: replaced regex-based approach with strip-and-unescape (handles "" → ")

Dialect Overrides

Processor	Quote char	Escape rule
DefaultSQLIdentifierProcessor	"	" → ""
MysqlIdentifierProcessor	backtick	` → ``
SqlServerIdentifierProcessor	[...]	] → ]]

PostgreSQL, KingBase, Oracle, DM, Oscar, SQLite all use " — inherit from Default without override.

Snowflake Accessor

• Added SNOWFLAKE_SQL_IDENTIFIER_PROCESSOR static field to SnowflakeMetaData, mirroring PostgreSQL's POSTGRE_SQL_IDENTIFIER_PROCESSOR and KingBase's KINGBASE_SQL_IDENTIFIER_PROCESSOR. This gives Snowflake column-type enums access to the processor for downstream quoting PRs.

Tests (36 tests, all passing)

DefaultSQLIdentifierProcessorTest (16 tests)

• quoteIdentifierAlways: wraps simple name, preserves mixed case, escapes embedded ", handles null, handles reserved keywords
• quoteIdentifier (conditional): doesn't quote lowercase valid, quotes invalid
• removeIdentifierQuote: strips and unescapes, passes through unquoted
• Round-trip: quoteIdentifierAlways → removeIdentifierQuote restores raw (tested with plain, mixed-case, embedded delimiter, reserved keyword, empty)

MysqlIdentifierProcessorTest (10 tests)

• quoteIdentifierAlways: wraps in backtick, escapes embedded backtick, preserves mixed case
• removeIdentifierQuote: strips backtick + double-quote, unescapes
• Round-trip with backtick

SqlServerIdentifierProcessorTest (10 tests)

• quoteIdentifierAlways: wraps in brackets, escapes embedded ]
• removeIdentifierQuote: strips brackets + double-quote, unescapes
• Round-trip with brackets

Verification

# SPI tests
mvn -B -f chat2db-community-server/pom.xml -pl chat2db-community-spi -am \
  -Dmaven.test.skip=false -DskipTests=false \
  -Dtest=DefaultSQLIdentifierProcessorTest \
  -Dsurefire.failIfNoSpecifiedTests=false -Dmaven.test.failure.ignore=false test
# → Tests run: 16, Failures: 0

# MySQL tests
mvn -B -f chat2db-community-server/pom.xml -pl chat2db-community-plugins/chat2db-community-mysql -am \
  -Dmaven.test.skip=false -DskipTests=false \
  -Dtest=MysqlIdentifierProcessorTest \
  -Dsurefire.failIfNoSpecifiedTests=false -Dmaven.test.failure.ignore=false test
# → Tests run: 10, Failures: 0

# SqlServer tests
mvn -B -f chat2db-community-server/pom.xml -pl chat2db-community-plugins/chat2db-community-sqlserver -am \
  -Dmaven.test.skip=false -DskipTests=false \
  -Dtest=SqlServerIdentifierProcessorTest \
  -Dsurefire.failIfNoSpecifiedTests=false -Dmaven.test.failure.ignore=false test
# → Tests run: 10, Failures: 0

Downstream (Phase 2)

Once this SPI extension merges, the 5 quoting PRs (#2145, #2169, #2185, #2186, #2187) will be reworked to use processor.quoteIdentifierAlways(name) instead of direct " concatenation:

PR	Plugin	Use
#2145	KingBase	KingBaseMetaData.KINGBASE_SQL_IDENTIFIER_PROCESSOR.quoteIdentifierAlways(name)
#2169	Snowflake	SnowflakeMetaData.SNOWFLAKE_SQL_IDENTIFIER_PROCESSOR.quoteIdentifierAlways(name)
#2185	Snowflake	SnowflakeMetaData.SNOWFLAKE_SQL_IDENTIFIER_PROCESSOR.quoteIdentifierAlways(schemaName)
#2186	Snowflake	quoteIdentifierAlways(oldName) + quoteIdentifierAlways(newName) in RENAME COLUMN
#2187	PG/KingBase	PostgreSQLMetaData.POSTGRE_SQL_IDENTIFIER_PROCESSOR / KingBaseMetaData.KINGBASE_SQL_IDENTIFIER_PROCESSOR

Contributor declaration

• I tested the affected behavior and reported the actual results above.
• I did not include credentials, private data, or generated build output.
• I disclosed substantial AI assistance below.

AI assistance: The implementation, tests, verification, and PR description were produced with Claude Code assistance.

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[Aias00]

Fixed the CI failure: the test mock class BacktickIdentifierProcessor in SqlCompletionMetadataProviderAdapterTest was missing the new quoteIdentifierAlways override required by the updated ISQLIdentifierProcessor interface. Added the method (backtick + escape ` -> ```). All 3 dependent PRs (#2261, #2262, #2265) have been rebased onto this fix.

[openai0229]

The shared SPI direction and delimiter round-trip tests are good, but this is not ready to merge yet. ISQLIdentifierProcessor is the public plugin SPI; adding a new non-default abstract method is source-incompatible for external implementations. Please provide a backward-compatible default or capability/versioned migration path and test that compatibility. This PR also changes removeIdentifierQuote semantics used by SQL parsing/completion callers, so add regression coverage at those caller boundaries rather than only direct processor round-trip tests.

[Aias00]

Changed quoteIdentifierAlways from an abstract method to a default method for backward compatibility with external implementations. The default delegates to quoteIdentifierIgnoreCase as a best-effort fallback; dialect implementations (Default, MySQL, SqlServer) still override for correct always-quote semantics. All 16 existing tests pass, and the test mock BacktickIdentifierProcessor still compiles because the override is now optional. All 3 dependent PRs (#2261, #2262, #2265) rebased.

[openai0229]

Maintainer follow-up completed on the original branch:

• rebased onto current main;
• kept the SPI source-compatible with a default method;
• made the fallback fail fast when an external processor cannot actually quote unconditionally;
• preserved the quote/remove round-trip for embedded delimiters;
• removed the unrelated Snowflake constant;
• added parser and completion caller-boundary regressions plus a legacy-implementation compatibility test.

Verification: the full test suites for chat2db-community-spi, chat2db-community-domain-core, chat2db-community-mysql, and chat2db-community-sqlserver passed with maven.test.skip=false and skipTests=false.