[magnusp]

Closes #43. Part of #54.

What changed

• File URLs now map to a namespace derived from the normalized absolute path. Relative paths are resolved against the process working directory and normalized before hashing, so a relative path and the equivalent absolute path address the same namespace.
• Path namespaces are retained after the last connection closes and reaped when the shared sqld container stops at suite end. Empty paths and :memory: remain isolated per-connection namespaces.
• URL query strings are ignored when deriving the namespace, so URL pragmas such as ?journal_mode=WAL do not change the namespace. This limitation is documented.
• Added XerialFileUrlPersistenceTest: it closes every connection, reopens the same file URL, and reads the table. A second test writes through an absolute path and reads through the equivalent relative path.
• Added libsql-conformance/README.md documenting the URL mapping, persistence, and suite scope.

Contract decision

I used the preferred retention design from Steering rather than the documented-ephemerality escape hatch. sqld keeps a namespace after its last connection closes, so retaining the path namespace until suite end is workable and gives the vendored tests SQLite-like close-and-reopen behavior. This is harness integrity, not an xerial parity decision; no xerial contract was changed.

Evidence

Run with mise exec --:

• Before the fix: ./mvnw -pl libsql-conformance -am -Dit.test=XerialFileUrlPersistenceTest verify
  • Result: BUILD FAILURE, 2 tests, 2 errors. Both new tests failed with SQLite error: no such table: persisted / SQLite error: no such table: mapped, proving the namespace was deleted on close and relative/absolute paths diverged.
• After the fix: the same command
  • Result: BUILD SUCCESS, 2 tests, 0 failures, 0 errors.
• ./mvnw -pl libsql-conformance -am verify
  • Result: BUILD SUCCESS, 117 tests, 0 failures, 0 errors, 1 skipped (the pre-existing @Disabled InsertQueryTest case).
• ./mvnw -pl libsql-jdbc -am test
  • Result: BUILD SUCCESS, 80 tests, 0 failures, 0 errors.
• ./mvnw spotless:apply
  • Result: BUILD SUCCESS, no files changed.

Deviations

None from the xerial contract. Harness limitation: URL pragmas remain ignored, now documented in the conformance README.