Spill a dynamic array from its anchor

A dynamic-array formula (e.g. =SEQUENCE) renders across the grid from its anchor — the anchor shows the array's first value and the rest spill into read-only echo cells; obstructing the range shows a spill conflict.

What it does

Type a dynamic-array formula — =SEQUENCE(3), =SEQUENCE(2,3), =A1:A3*2 — and the result spills across the grid from the cell you typed it into (the anchor). The anchor keeps the formula and shows the array's top-left value; the remaining cells fill with read-only echoes of the result. Selecting any cell in the range outlines the whole spilled region with a subtle blue spill boundary, matching Google Sheets. If a cell the array needs is already occupied, the spill can't land: the anchor shows a spill conflict and the blocking value is left untouched.

Verified behavior

Matches Google Sheets: In Google Sheets a dynamic-array formula computes at its ANCHOR cell and "spills" the result across neighbouring cells. The anchor holds the formula and displays the array's top-left value; the other cells are read-only echoes of the result and carry no formula of their own. Orientation follows the array's shape — =SEQUENCE(3) spills DOWN a 3x1 column (A1:A3 = 1,2,3), =SEQUENCE(1,3) spills ACROSS a 1x3 row (A1:C1 = 1,2,3), and =SEQUENCE(2,3) fills a 2x3 block. An operation over a source RANGE derives its orientation from that range (observed live in Sheets 2026-08-05, oracle obs. 6-9): =SORT(A1:A3), =UNIQUE(A1:A3) and =FILTER(A1:A3,...) over a vertical A1:A3 are all N x 1 and spill DOWN, while =TRANSPOSE(A1:A3) is the one that flips — a single-column source becomes a 1 x N ROW that spills ACROSS. Elementwise range arithmetic needs the explicit wrapper in Sheets: a bare =A1:A32 returns a SINGLE row-aligned value there, and =ARRAYFORMULA(A1:A32) is what yields the 3 x 1 column. TrueCalc's engine spills the bare form too — a deliberate engine divergence recorded in the oracle brief — and when it does, it uses the same vertical orientation Sheets gives the ARRAYFORMULA form. When a cell within a spill cell is selected, Sheets outlines the whole spilled range with a thin blue "spill boundary". If any target cell is occupied the array cannot spill: the anchor shows #SPILL!, no values spill, and the blocking value is preserved. (The orientation parity gap tracked in truecalc/core#707 is resolved as of @truecalc/workbook 7.x — every family above now matches Sheets' orientation; earlier engines emitted 1 x N rows for the derived single-column results and a column for TRANSPOSE, i.e. exactly backwards. The blocked-spill error is still #SPILL! in Sheets vs a generic error in the current engine. See the oracle brief.)