Copy rows/ranges across worksheets preserving styles, formulas, and merges

Cluster: core-model

Scenario

A user consolidates several files into one workbook by copying rows from source worksheets into a destination, expecting the copied rows to carry over not just values but cell styles, number formats, formulas, and merged-cell ranges. Naive value-only copying loses formatting, and copying rows that contain shared-formula member cells whose master lies outside the copied region trips the same "master must exist above/left of clone" failure locked as a known-open in shared-formula-master-survives-roundtrip-and-splice. Users resort to Object.assign over row objects, which happens to drag style internals along but silently breaks on formulas and merges.

Spec note, not a corpus case: this is a first-class API that does not exist yet. The durable value is the copy semantics, meaning what must be preserved and how the hard edges (shared formulas, merges, cross-workbook style tables) are handled.

Desired behavior

• A well-typed way to copy a row, or a range of rows or cells, from one worksheet to another: the same sheet, another sheet in the same workbook, or a sheet in a different loaded workbook, preserving values, cell styles, number formats, alignment, fill, borders, formulas, and merged ranges.
• Resilient to shared formulas. When a copied cell participates in a shared formula whose master lies outside the copied region, the copy must not crash. It either materializes the concrete formula for that cell, expanding the shared formula into a plain one, or re-anchors a new shared-formula master within the destination. It never throws the master-position error.
• Merged ranges intersecting the copied region are reconstructed in the destination at the corresponding offset.
• Cross-workbook copies remap style and number-format references into the destination's style table rather than dangling indices into the source's.

Open questions

• API shape: dst.addRow(srcRow) that deep-copies, a copyRange(srcRange, dstAnchor) helper, or a Range model shared with sort-rows-by-column and set-style-over-cell-range?
• Formula policy default: expand shared formulas to concrete per-cell formulas (simple, lossless in value) or re-anchor a shared master (compact)? And are relative references rebased to the new position?
• Does a cross-workbook copy also carry defined names and conditional formats referenced by the copied rows, or only the cell-local state?

Related: shared-formula-master-survives-roundtrip-and-splice, sort-rows-by-column, set-style-over-cell-range, worksheet-model-preserves-merged-cells, copyWorksheetModel.