Purpose

docs/docs/pypaimon/system-tables.md still describes behavior that PyPaimon no longer has.

• with_filter is documented as always raising NotImplementedError. System-table reads already apply equality, comparison, in, null checks, and string predicates (startswith, endswith, contains, like) in memory, before projection and limit. Value comparisons on nested columns such as $files.write_cols still raise NotImplementedError.
• $tags.create_time and time_retained are documented as always NULL. They are NULL only when the tag was created without retention. A tag created with time_retained fills create_time and stores the duration as Java Duration text (1d becomes PT24H).
• $manifests.min_partition_stats and max_partition_stats are documented as always NULL. They now use the same {v1, v2} text as Java ({} for an unpartitioned table). The value stays NULL only when a partition field is FLOAT, DOUBLE, TIMESTAMP_LTZ, BINARY, VARBINARY, or BYTES.

Tests

Documentation only. No runtime code changes. The behavior is already covered by system_string_filter_test.py, tags_table_test.py, and manifests_table_test.py.