diff --git a/crates/engine/src/cmd/table.rs b/crates/engine/src/cmd/table.rs
index 91ac7ac70..7ea66acfd 100644
--- a/crates/engine/src/cmd/table.rs
+++ b/crates/engine/src/cmd/table.rs
@@ -1,7 +1,7 @@
 //! Table Design and Table Layout tabs.
 
 use deckcraft_geom::{Affine, Point, Rect};
-use deckcraft_model::{Shape, ShapeKind, Table};
+use deckcraft_model::{Cell, Shape, ShapeKind, Table};
 use serde_json::{Value, json};
 
 use super::{
@@ -24,18 +24,24 @@ pub fn specs() -> Vec<CommandSpec> {
             "rowBelow",
             "table.insertRowBelow"
         )),
-        cmd!("table.insertColumnLeft", "Insert Left", ["Table Layout", "Rows & Columns"], None, "{col?, id?}", has_selection, |s, p| rows_cols(
-            s,
-            p,
-            "colLeft",
-            "table.insertColumnLeft"
-        )),
-        cmd!("table.insertColumnRight", "Insert Right", ["Table Layout", "Rows & Columns"], None, "{col?, id?}", has_selection, |s, p| rows_cols(
-            s,
-            p,
-            "colRight",
-            "table.insertColumnRight"
-        )),
+        cmd!(
+            "table.insertColumnLeft",
+            "Insert Left",
+            ["Table Layout", "Rows & Columns"],
+            None,
+            "{col?, keepWidth?: bool (default false, as in PowerPoint: the table grows by the new column and the other widths stay; true: the other columns shrink in proportion so the table keeps its width), id?} the new column takes the width and cell formatting (fill, margins, anchor, text properties) of the column it is inserted beside; a merged row that spans that column grows to span the new one",
+            has_selection,
+            |s, p| rows_cols(s, p, "colLeft", "table.insertColumnLeft")
+        ),
+        cmd!(
+            "table.insertColumnRight",
+            "Insert Right",
+            ["Table Layout", "Rows & Columns"],
+            None,
+            "{col?, keepWidth?: bool (default false, as in PowerPoint: the table grows by the new column and the other widths stay; true: the other columns shrink in proportion so the table keeps its width), id?} the new column takes the width and cell formatting (fill, margins, anchor, text properties) of the column it is inserted beside; a merged row that spans that column grows to span the new one",
+            has_selection,
+            |s, p| rows_cols(s, p, "colRight", "table.insertColumnRight")
+        ),
         cmd!("table.deleteRow", "Delete Rows", ["Table Layout", "Rows & Columns"], None, "{row?, id?}", has_selection, |s, p| rows_cols(
             s,
             p,
@@ -315,13 +321,22 @@ fn with_table(s: &mut Session, p: &Value, cmd: &str, f: impl Fn(&mut Table) -> R
 
 fn rows_cols(s: &mut Session, p: &Value, op: &str, name: &'static str) -> Result<Value> {
     let (r, c) = at(s, p, name)?;
+    // Absent: the table grows, as in PowerPoint; present, it must be a bool, so a mistyped value is refused
+    // rather than silently taken as the default.
+    let keep_width = match (op, p.get("keepWidth")) {
+        (_, None) | (_, Some(Value::Null)) => false,
+        (_, Some(Value::Bool(b))) => *b,
+        ("colLeft", Some(_)) => return Err(bad("table.insertColumnLeft", "`keepWidth` must be true or false")),
+        ("colRight", Some(_)) => return Err(bad("table.insertColumnRight", "`keepWidth` must be true or false")),
+        _ => false,
+    };
     let op = op.to_string();
     with_table(s, p, name, move |t| {
         match op.as_str() {
             "rowAbove" => t.insert_row(r),
             "rowBelow" => t.insert_row(r.saturating_add(1)),
-            "colLeft" => t.insert_col(c),
-            "colRight" => t.insert_col(c.saturating_add(1)),
+            "colLeft" => insert_col_like(t, c, c, keep_width),
+            "colRight" => insert_col_like(t, c.saturating_add(1), c, keep_width),
             "delRow" => {
                 if !t.delete_row(r) {
                     return Err(bad(name, "can't delete the last row"));
@@ -337,6 +352,65 @@ fn rows_cols(s: &mut Session, p: &Value, op: &str, name: &'static str) -> Result
     })
 }
 
+/// Insert a column before `at` that looks like column `neighbour` (the one it is inserted beside):
+/// its width, and in every row the neighbour cell's explicit formatting with no text. With
+/// `keep_width` the columns then shrink in proportion so the table keeps its total width;
+/// otherwise (PowerPoint's behaviour) the table grows by the new column and the widths stay.
+fn insert_col_like(t: &mut Table, at: usize, neighbour: usize, keep_width: bool) {
+    let total = t.width();
+    let neighbour = neighbour.min(t.cols.len().saturating_sub(1));
+    let w = t.cols.get(neighbour).copied();
+    let templates: Vec<Option<Cell>> = t.rows.iter().map(|r| r.cells.get(neighbour).cloned()).collect();
+    t.insert_col_beside(at, Some(neighbour));
+    let at = at.min(t.cols.len().saturating_sub(1));
+    if let (Some(w), Some(slot)) = (w, t.cols.get_mut(at)) {
+        *slot = w;
+    }
+    for (row, tpl) in t.rows.iter_mut().zip(templates) {
+        let Some(tpl) = tpl else { continue };
+        // Inserted left of a merge's anchor, the merge now starts at the new cell, which took the
+        // anchor's cell whole, text and formatting (Table::insert_col_beside); the old anchor,
+        // covered now, is the empty cell that gets the neighbour's formatting. Read off the table
+        // as it is now: a span the file lets run past the last column is no merge to the model.
+        let anchor_moved = row.cells.get(at).is_some_and(|c| c.grid_span > 1 && !c.is_covered());
+        if let Some(cell) = row.cells.get_mut(if anchor_moved { at + 1 } else { at }) {
+            copy_cell_format(cell, &tpl);
+        }
+    }
+    let grown = t.width();
+    if keep_width && total > 1e-9 && grown > 1e-9 {
+        let k = total / grown;
+        for cw in &mut t.cols {
+            *cw *= k;
+        }
+    }
+}
+
+/// `dst` takes `src`'s formatting (fill, borders, margins, anchor, text direction and the text
+/// properties of its first paragraph, kept on the end mark of an empty paragraph) and keeps its
+/// own spans and merge cover.
+fn copy_cell_format(dst: &mut Cell, src: &Cell) {
+    dst.fill.clone_from(&src.fill);
+    dst.borders.clone_from(&src.borders);
+    dst.diag_down.clone_from(&src.diag_down);
+    dst.diag_up.clone_from(&src.diag_up);
+    dst.margins = src.margins;
+    dst.anchor = src.anchor;
+    dst.vertical = src.vertical;
+    let para = src.text.paragraphs.first().map(|p0| deckcraft_model::text::Paragraph {
+        level: p0.level,
+        props: p0.props.clone(),
+        runs: vec![],
+        def_props: p0.def_props.clone(),
+        end_props: p0.runs.first().map_or_else(|| p0.end_props.clone(), |r| r.props.clone()),
+    });
+    dst.text = deckcraft_model::text::TextBody {
+        body: src.text.body.clone(),
+        list_style: src.text.list_style.clone(),
+        paragraphs: vec![para.unwrap_or_default()],
+    };
+}
+
 fn merge(s: &mut Session, p: &Value) -> Result<Value> {
     let sel = s.doc()?.selection.cells;
     let from = cell_param(p, "from", "table.merge")?.or(sel.map(|c| c.1)).ok_or_else(|| bad("table.merge", "missing `from`"))?;
diff --git a/crates/engine/src/tests.rs b/crates/engine/src/tests.rs
index 85cbe9d8c..2fd3c23ec 100644
--- a/crates/engine/src/tests.rs
+++ b/crates/engine/src/tests.rs
@@ -5956,3 +5956,144 @@ fn invalid_slide_index_never_falls_back_to_the_selection_in_export_commands() {
     }
     let _ = std::fs::remove_dir_all(&dir);
 }
+
+/// A `keepWidth` that is not a bool is refused, naming it, and the table is left alone; it used
+/// to be read as absent and the columns shrunk as if `true` had been asked.
+#[test]
+fn table_insert_column_refuses_a_keep_width_that_is_not_a_bool() {
+    let mut s = session();
+    let id = table_at(&mut s, &[280.0, 280.0, 280.0], json!([["a", "b", "c"]]));
+    for (cmd, bad) in [("table.insertColumnRight", json!("false")), ("table.insertColumnLeft", json!(0))] {
+        let err = s.execute(cmd, &json!({"id": id.0, "col": 1, "keepWidth": bad})).unwrap_err().to_string();
+        assert!(err.contains("keepWidth") && err.contains(cmd), "{err}");
+        let t = table_of(&s, id);
+        assert_eq!(t.n_cols(), 3, "{cmd} changed the table: {:?}", t.cols);
+        assert!((t.width() - 840.0).abs() < 1e-6, "width {}", t.width());
+    }
+}
+
+#[test]
+fn table_insert_column_extends_a_merge_that_spans_the_neighbour() {
+    let mut s = session();
+    let id = table_at(&mut s, &[100.0, 100.0, 100.0], json!([["title", "", ""], ["a", "b", "c"]]));
+    s.execute("table.merge", &json!({"id": id.0, "from": [0, 0], "to": [0, 2]})).unwrap();
+    s.execute("table.insertColumnRight", &json!({"id": id.0, "col": 2})).unwrap();
+    let t = table_of(&s, id);
+    assert_eq!(t.cell(0, 0).unwrap().grid_span, 4, "the title now spans the new column");
+    assert!(t.cell(0, 3).unwrap().h_merge);
+    assert_eq!(t.cell(1, 0).unwrap().grid_span, 1);
+    s.execute("table.insertColumnLeft", &json!({"id": id.0, "col": 0})).unwrap();
+    let t = table_of(&s, id);
+    assert_eq!(t.cell(0, 0).unwrap().grid_span, 5, "left of the first column too");
+    assert_eq!(t.cell(0, 0).unwrap().text.text(), "title");
+}
+
+/// A span a file lets run past the last column is no merge to the model, so inserting left of
+/// that cell adds a plain column: the cell keeps its text and the new one gets its formatting.
+#[test]
+fn table_insert_column_left_of_an_overflowing_span_keeps_the_text() {
+    let mut s = session();
+    let id = table_at(&mut s, &[100.0, 100.0, 100.0], json!([["a", "b", "wide"], ["d", "e", "f"]]));
+    {
+        let doc = std::sync::Arc::make_mut(&mut s.doc_mut().unwrap().doc);
+        let slide = std::sync::Arc::make_mut(&mut doc.slides[0]);
+        let sh = deckcraft_model::find_shape_mut(&mut slide.shapes, id).unwrap();
+        let deckcraft_model::ShapeKind::Table(t) = &mut sh.kind else { panic!("a table") };
+        t.cell_mut(0, 2).unwrap().grid_span = 4;
+    }
+    s.execute("table.cellFill", &json!({"id": id.0, "color": "#FF0000", "cells": [[0, 2]]})).unwrap();
+    s.execute("table.insertColumnLeft", &json!({"id": id.0, "col": 2})).unwrap();
+    let t = table_of(&s, id);
+    assert_eq!(t.n_cols(), 4);
+    assert_eq!(t.cell(0, 3).unwrap().text.text(), "wide", "the cell keeps its text");
+    assert_eq!(t.cell(0, 2).unwrap().text.text(), "");
+    assert_eq!(t.cell(0, 2).unwrap().fill, t.cell(0, 3).unwrap().fill, "the new cell takes the neighbour's fill");
+}
+
+#[test]
+fn table_insert_column_with_keep_width_keeps_the_table_width_and_copies_the_neighbour_format() {
+    let mut s = session();
+    let id = table_at(&mut s, &[280.0, 280.0, 280.0], json!([["a", "b", "c"], ["d", "e", "f"]]));
+    s.execute("table.cellFill", &json!({"id": id.0, "color": "#FF0000", "cells": [[0, 2], [1, 2]]})).unwrap();
+    s.execute("table.cellMargins", &json!({"id": id.0, "left": 20, "right": 20, "top": 5, "bottom": 5, "cells": [[0, 2]]})).unwrap();
+    s.execute("table.cellAlign", &json!({"id": id.0, "anchor": "bottom", "cells": [[0, 2]]})).unwrap();
+    s.execute("edit.select", &json!({"ids": [id.0]})).unwrap();
+    s.execute("table.selectCells", &json!({"from": [0, 2], "to": [1, 2]})).unwrap();
+    s.execute("format.bold", &json!({"on": true})).unwrap();
+    // Right of the last column: four columns in the same 840 pt, the new one as wide as its
+    // neighbour, the others shrunk to make room.
+    s.execute("table.insertColumnRight", &json!({"id": id.0, "col": 2, "keepWidth": true})).unwrap();
+    let t = table_of(&s, id);
+    assert_eq!(t.n_cols(), 4);
+    assert!((t.width() - 840.0).abs() < 1e-6, "width {}", t.width());
+    assert!(t.cols.iter().all(|w| (w - 210.0).abs() < 1e-6), "{:?}", t.cols);
+    let x = s.doc().unwrap().shape(id).unwrap().xfrm.unwrap();
+    assert!((x.w - 840.0).abs() < 1e-6, "frame {}", x.w);
+    // The new cells take the neighbour's explicit formatting.
+    let new = t.cell(0, 3).unwrap();
+    assert_eq!(new.fill, Some(deckcraft_model::Fill::solid(deckcraft_model::ColorRef::rgb(deckcraft_color::Rgba::rgb(255, 0, 0)))));
+    assert_eq!(new.margins, Some([20.0, 20.0, 5.0, 5.0]));
+    assert_eq!(new.anchor, Some(deckcraft_model::text::Anchor::Bottom));
+    assert_eq!(new.text.text(), "", "the new cell is empty");
+    let bold = new.text.paragraphs.first().map(|p| p.end_props.bold.or(p.def_props.bold));
+    assert_eq!(bold, Some(Some(true)), "the neighbour's bold carries over: {:?}", new.text);
+    assert_eq!(t.cell(1, 3).unwrap().fill, t.cell(1, 2).unwrap().fill);
+    // Left of the first column: the neighbour is the old first column.
+    s.execute("table.insertColumnLeft", &json!({"id": id.0, "col": 0, "keepWidth": true})).unwrap();
+    let t = table_of(&s, id);
+    assert_eq!(t.n_cols(), 5);
+    assert!((t.width() - 840.0).abs() < 1e-6, "width {}", t.width());
+    assert_eq!(t.cell(0, 1).unwrap().text.text(), "a");
+    assert_eq!(t.cell(0, 0).unwrap().fill, None);
+    // keepWidth: false grows the table by the neighbour's width, as before.
+    s.execute("table.insertColumnRight", &json!({"id": id.0, "col": 4, "keepWidth": false})).unwrap();
+    let t = table_of(&s, id);
+    assert_eq!(t.n_cols(), 6);
+    assert!((t.width() - 840.0 - 168.0).abs() < 1e-6, "width {}", t.width());
+    // The insertion is journaled as called, and each one is a single undo step back to the table
+    // as it was: the columns, their widths and the frame.
+    let (jid, jp) = s.journal.last().cloned().unwrap();
+    assert_eq!(jid, "table.insertColumnRight");
+    assert_eq!(jp["keepWidth"], json!(false), "{jp}");
+    s.execute("edit.undo", &json!({})).unwrap();
+    let t = table_of(&s, id);
+    assert_eq!(t.n_cols(), 5);
+    assert!((t.width() - 840.0).abs() < 1e-6, "width {}", t.width());
+    s.execute("edit.undo", &json!({})).unwrap();
+    s.execute("edit.undo", &json!({})).unwrap();
+    let t = table_of(&s, id);
+    assert_eq!(t.n_cols(), 3);
+    assert!(t.cols.iter().all(|w| (w - 280.0).abs() < 1e-6), "{:?}", t.cols);
+    assert_eq!(t.cell(0, 2).unwrap().text.text(), "c");
+    let x = s.doc().unwrap().shape(id).unwrap().xfrm.unwrap();
+    assert!((x.w - 840.0).abs() < 1e-6, "frame {}", x.w);
+}
+
+/// PowerPoint inserts a column as wide as its neighbour and widens the table by that amount; the
+/// other widths stay. Deleting a column narrows the table by its width, the others untouched.
+#[test]
+fn table_insert_and_delete_column_leave_other_widths_alone() {
+    let mut s = session();
+    let id = table_at(&mut s, &[160.0, 234.0, 235.0, 235.0], json!([["a", "b", "c", "d"]]));
+    for (cmd, col, at, wide) in [("table.insertColumnRight", 0, 1, 160.0), ("table.insertColumnLeft", 3, 3, 235.0)] {
+        let before = table_of(&s, id).cols.clone();
+        let w0 = table_of(&s, id).width();
+        s.execute(cmd, &json!({"id": id.0, "col": col})).unwrap();
+        let t = table_of(&s, id);
+        let mut want = before.clone();
+        want.insert(at, wide);
+        assert_eq!(t.cols, want, "{cmd}");
+        assert!((t.width() - w0 - wide).abs() < 1e-6, "{cmd} width {}", t.width());
+        let x = s.doc().unwrap().shape(id).unwrap().xfrm.unwrap();
+        assert!((x.w - t.width()).abs() < 1e-6, "{cmd} frame {}", x.w);
+    }
+    let before = table_of(&s, id).cols.clone();
+    s.execute("table.deleteColumn", &json!({"id": id.0, "col": 1})).unwrap();
+    let t = table_of(&s, id);
+    let mut want = before.clone();
+    let gone = want.remove(1);
+    assert_eq!(t.cols, want);
+    assert!((t.width() - (before.iter().sum::<f64>() - gone)).abs() < 1e-6);
+    let x = s.doc().unwrap().shape(id).unwrap().xfrm.unwrap();
+    assert!((x.w - t.width()).abs() < 1e-6, "frame {}", x.w);
+}
diff --git a/crates/model/src/table.rs b/crates/model/src/table.rs
index 0705d1a08..ce0f0434a 100644
--- a/crates/model/src/table.rs
+++ b/crates/model/src/table.rs
@@ -116,6 +116,12 @@ impl Table {
     }
     /// Insert an empty column before `at`. A merge the new column falls inside grows to cover it.
     pub fn insert_col(&mut self, at: usize) {
+        self.insert_col_beside(at, None);
+    }
+    /// Like [`Table::insert_col`], for a column inserted beside column `neighbour` (as before the
+    /// insertion): a horizontal merge that spans the neighbour also grows over the new column, even when the
+    /// insertion point is at its edge.
+    pub fn insert_col_beside(&mut self, at: usize, neighbour: Option<usize>) {
         let at = at.min(self.cols.len());
         let merges = self.merges();
         let w = self.cols.get(at.saturating_sub(1)).copied().unwrap_or(80.0);
@@ -124,7 +130,13 @@ impl Table {
             let i = at.min(r.cells.len());
             r.cells.insert(i, Cell::new(""));
         }
-        self.set_merges(merges.into_iter().map(|m| m.insert_col(at)));
+        let grows = |m: &Merge| matches!(neighbour, Some(n) if m.gs > 1 && m.c <= n && n < m.c + m.gs && (at == m.c || at == m.c + m.gs));
+        // A merge that grows to the left starts at the new cell, which takes the anchor's text and
+        // formatting; the old anchor becomes a covered, empty cell.
+        for m in merges.iter().filter(|m| grows(m) && at == m.c) {
+            self.move_anchor((m.r, at + 1), (m.r, at));
+        }
+        self.set_merges(merges.into_iter().map(|m| if grows(&m) { Merge { gs: m.gs + 1, ..m } } else { m.insert_col(at) }));
     }
     /// Delete row `at`. Merges through it shrink; a merge anchored on it moves its anchor (and
     /// text) to the next row it covers.
@@ -638,4 +650,24 @@ mod tests {
         assert!(t.split(0, 0));
         assert_eq!(t.cell(0, 0).map(|c| (c.grid_span, c.row_span)), Some((1, 1)));
     }
+
+    /// A column inserted left of a merge's anchor grows the merge, which now starts at the new
+    /// cell: that cell holds the text, and the old anchor is a covered, empty cell.
+    #[test]
+    fn a_column_inserted_left_of_a_merge_keeps_the_text_in_its_anchor() {
+        let mut t = merged();
+        t.insert_col_beside(1, Some(1));
+        assert_topology(&t);
+        let a = t.cell(1, 1).unwrap();
+        assert_eq!((a.grid_span, a.row_span), (3, 2));
+        assert_eq!(anchor_text(&t, 1, 1), "M");
+        assert!(t.cell(1, 2).unwrap().is_covered());
+        assert_eq!(anchor_text(&t, 1, 2), "");
+        // Right of the merge, the anchor stays where it is.
+        let mut t = merged();
+        t.insert_col_beside(3, Some(2));
+        assert_topology(&t);
+        assert_eq!(t.cell(1, 1).map(|c| c.grid_span), Some(3));
+        assert_eq!(anchor_text(&t, 1, 1), "M");
+    }
 }