Type: the Every-line Composer sets the visible lines of a mixed-size paragraph that overflows a shaped frame

A paragraph whose characters differ in line metrics, in area type that is
not a rectangle or that wraps around an object, was broken line by line
with the Single-line Composer when the frame could not hold all of it.
The lines the frame holds are now composed with the whole paragraph: a
line the frame has no room for, and every line after it, is measured as
wide as the span of the last line set in the frame, less its indents.
Those lines overflow, or go on in the next threaded frame, which composes
them again at its own widths. A paragraph whose first line has no room,
and a search that passes its limits, still fall back to Single-line.

Docs: docs/mcp.md, docs/target-app-parity.md.

docs/mcp.md

@@ -10445,9 +10445,13 @@ give the same result there. A paragraph whose characters differ in line metrics
 scale, or an inline graphic taller than the text) is composed with Every-line in area type of any shape, rows,
 columns and text wrap included. In a frame that is not a rectangle, or with text wrap, each line it tries is measured
 where the lines above it put it, across the line's own height, so a taller line that reaches where the frame is
-narrower, or beside a wrap object, gets the room there. Such a paragraph falls back to Single-line when the frame has
-no room for all of it, or when the search for its breaks passes VectorCraft's own limits (1,000,000 lines tried and
-2,000,000 baseline steps for one paragraph, 2,000,000 lines and 4,000,000 steps for all the paragraphs of a frame).
+narrower, or beside a wrap object, gets the room there. When the frame has no room for all of such a paragraph, the
+lines it holds are still composed with the whole paragraph: VectorCraft measures the lines past the frame's end as
+wide as the span of the last line the frame holds, less their indents. Those lines overflow, or go on in the next
+threaded frame, which composes them again at its own widths. Such a paragraph falls back to Single-line when the
+frame has no room for its first line, or when the search for its breaks passes VectorCraft's own limits (1,000,000
+lines tried and 2,000,000 baseline steps for one paragraph, 2,000,000 lines and 4,000,000 steps for all the
+paragraphs of a frame).
 The UI command `type.lineComposer` (Cmd+Alt+Shift+C, in remote mode `press_key {key: "C", mods: {cmd: true, alt: true,
 shift: true}}` or `invoke_menu`) sets `singleLine` when every paragraph of the selected type (or every paragraph the
 Type tool's selection touches) uses Every-line, else `everyLine`, and returns the composer it set.