DataFusion non-append InsertOp is silently committed as append

[u70b3]

Apache Iceberg Rust version

Current main at ac92ec9 (version 0.10.0).

Describe the bug

IcebergTableProvider::insert_into accepts DataFusion's InsertOp, but currently ignores it. The physical commit path always uses Transaction::fast_append.

As a result, InsertOp::Overwrite or InsertOp::Replace can be planned and executed as an append instead of returning an unsupported-operation error. This can produce incorrect table contents because the requested write semantics are silently changed.

To Reproduce

1. Construct an IcebergTableProvider backed by a catalog.
2. Call TableProvider::insert_into with a valid input plan and InsertOp::Overwrite or InsertOp::Replace.
3. Observe that an IcebergCommitExec plan is returned.
4. The commit executor subsequently commits generated files through fast_append.

Relevant code:

• crates/integrations/datafusion/src/table/mod.rs ignores the InsertOp argument.
• crates/integrations/datafusion/src/physical_plan/commit.rs unconditionally uses fast_append.

Expected behavior

Until overwrite and replace semantics are implemented end to end, IcebergTableProvider::insert_into should accept only InsertOp::Append and return a clear unsupported/not-implemented error for Overwrite and Replace before constructing a write plan.

Willingness to contribute

I can contribute a fix for this bug independently.