[magnusp]

Fixes #114
Closes #27

Contract

Hrana 3 is the source of truth for transport, values, metadata, batching, transactions, and error reporting. java.sql is the source of truth for the JDBC surface. xerial/sqlite-jdbc is a behavioral reference and conformance foundation, never a copy target.

Protocol basis: Value.Blob is base64 on the wire, so streams and blobs materialize locally from the decoded bytes. Unsupported optional features throw SQLFeatureNotSupportedException per JDBC.

What changed

• LibsqlResultSet: every remaining UnsupportedOperationException replaced with SQLFeatureNotSupportedException (all update*, getRef, getArray, getURL, getRowId, getNClob, getSQLXML, getAsciiStream, getUnicodeStream, getNCharacterStream).
• getBinaryStream(int/String) over getBytes and getCharacterStream(int/String) over getString; SQL NULL returns null.
• Read-only getBlob(int/String) and getClob(int/String) over the materialized value, with the full read side of java.sql.Blob/Clob; write methods throw SQLFeatureNotSupportedException.
• getObject(int, Map) and getObject(String, Map) reject a non-empty map with SQLFeatureNotSupportedException("Type maps are not supported"); null and empty maps keep the existing behavior.
• findColumn(null) throws SQLException("column label cannot be null") instead of NullPointerException.
• LibsqlDatabaseMetaData: 14 unsupported metadata methods now throw SQLFeatureNotSupportedException.

#27 answer

Read side supported: getBlob/getClob and the full read surface of Blob/Clob (length, getBytes/getSubString, streams, position, free), plus getBinaryStream and getCharacterStream.

Write side not supported: PreparedStatement.setBlob/setClob and the Blob/Clob mutators are outside this PR's Files block and still throw SQLFeatureNotSupportedException. getAsciiStream, getUnicodeStream, and getNCharacterStream also remain unsupported (see divergences).

Divergences

• xerial supports getAsciiStream, getUnicodeStream, and getNCharacterStream; this PR leaves them unsupported because the plan's Build limits stream implementation to getBinaryStream and getCharacterStream. They now throw the checked JDBC exception, so catch (SQLException) callers survive.
• xerial returns unsupported for getBlob; this driver implements it because Hrana already carries the decoded blob bytes and [Bug]: check for BLOB support #27 asks for blob support. It is read-only.
• xerial throws unsupported for getObject(Map) unconditionally; this driver accepts null and empty maps and rejects only a non-empty map, matching fix(jdbc): reject unsupported type maps and report holdability #95's setTypeMap contract.

Evidence

Red (trunk 1c240cd with these test files, /tmp/xerial-parity-i114/lane-1-regression.log): 67 tests, 4 failures and 4 errors. The new stream, blob, map, findColumn, and sweep cases fail on UnsupportedOperationException, the ignored type map, and the null-label NPE.

Green (head 47ea3f2, same log): 67 tests, 0 failures, BUILD SUCCESS.

Lanes (logs under /tmp/xerial-parity-i114/):

1. Regression, trunk red to head green: pass.
2. Byte-for-byte stream content: 4 tests pass.
3. Unchecked-exception sweep over both classes: 2 tests pass, no UnsupportedOperationException.
4. ./mvnw -pl libsql-jdbc test: 273 tests, BUILD SUCCESS.
5. ./mvnw -pl libsql-conformance -am verify: 123 tests, 1 skipped, BUILD SUCCESS, no new divergence.
6. ./mvnw -pl libsql-conformance -am -Pxerial-control verify: 100 tests, 1 skipped, BUILD SUCCESS.
7. ./mvnw spotless:check: BUILD SUCCESS.
8. ./mvnw test: BUILD SUCCESS.
9. [Bug]: check for BLOB support #27 surface: recorded in lane-9-specific.log.
10. ./mvnw -pl libsql-jdbc -am package -DskipTests: jar built.

Perf: ./mvnw -pl libsql-jdbc test medians over three interleaved runs, trunk 2.159 s versus head 2.167 s, +0.4 percent, within the 10 percent rule.

Files touched: only the four files in the plan's Files block. Base 1c240cd, head 47ea3f2.