Review outcome: no blocking code issues found. Approval opinion: approve.

Critical checkpoint conclusions:

• Goal and scope: the PR moves the two-way PrimitiveType/FieldType conversion out of TabletColumn, migrates every in-repository caller, documents the enum-maintenance contract, and adds a registered table-driven unit test. The authoritative 14-file bundle matches its diff, and repository-wide searches found no stale declaration or call to either removed helper.
• Correctness and error handling: the new switches cover every named enum value. Valid callers keep their mappings; unsupported and out-of-range values now fail deterministically instead of propagating UNKNOWN/INVALID sentinels or indexing beyond the old reverse-mapping array. No ignored Status, exception-in-destructor, ownership, null/COW, allocation, or memory-tracking behavior changes.
• Compatibility, persistence, and parallel paths: every previously supported sparse-VARIANT tag retains the same persisted byte. Dense-to-sparse writers, recursive arrays/nulls, field/column dispatch, least-common-type handling, and sparse merge/compaction were traced. DecimalV2 changes from UNKNOWN/21 to DECIMAL/16 in its direct binary writer, but both the old and new payloads are rejected by the already-unsupported DecimalV2 sparse reader path; UINT32/UINT64 are offset-only and have no logical SerDe producer. No previously readable rowset or supported rolling-upgrade path regresses.
• Concurrency, lifecycle, configuration, observability, and security: not applicable. The helpers are pure stateless switches; no shared state, lock, thread, cleanup, configuration, logging/metrics/tracing, or trust boundary changes.
• Performance: the migrated hot paths replace one enum conversion with another and add no copy, scan, allocation, materialization, or lock.
• Tests and validation: the new test covers all supported mappings, unsupported/invalid values, two-way round trips, and all persisted FieldType ordinals; recursive CMake globs include both the implementation and test. git diff --check, CheckStyle, and Clang Formatter passed. Per the automation contract I did not build locally; live BE UT, macOS BE UT, and COMPILE checks were still pending at the final sweep. Separately, the PR title check is failing because the configured prefix regex does not accept the dot in [branch-4.1]; the code-review opinion remains approve, but that merge check needs resolution.
• Review-environment limitation: the expected repository .claude/skills/code-review/SKILL.md file is absent from this checkout, so the review followed the bundle contract and the available Doris review workflow directly.

User focus: no additional focus points were provided; the complete PR was reviewed.

Review completion: one full cyclic review round plus an unchanged-set convergence pass; both normal full-review subagents and the separate risk-focused subagent returned NO_NEW_VALUABLE_FINDINGS, every initial risk has an evidence-backed conclusion, and the final changed-file/unresolved-candidate sweep is clean.