fix(docx): space a centred or right-aligned line of its own to the page's width

CHANGELOG.md

@@ -8,6 +8,18 @@ follow semantic versioning; release dates are ISO 8601.
 
 ### Public API
 
+- **A centred or right-aligned DOCX line of its own stands as wide as the page sets it.**
+  Word states a type size in half points, and a line set at a size the page gives to the tenth
+  is that much wider or narrower, a centred or right-aligned one moving its first letter with
+  it: `CenteredHeadline`'s 8.3pt contact line, set at 8.5, stood 10pt wider in Word and its
+  first letter 4pt left of the page's, and `ClassicSerif`'s 8.7pt one 4pt right. Where a
+  left-to-right line of text alone differs by a point or more, its letters are now spaced by
+  it (`w:spacing`), the size left as Word sets it, so the line's ends stand within a fraction
+  of a point of the page's, and its room is reckoned from the page's width; a line that is
+  tracked or carries a picture or a shape, and a difference under a point, are left as they
+  are, room included. Lines more than 2pt off across fall from 23 to 12 in Word (74 lines
+  nearer the page, one 0.02pt further) and from 29 to 18 in LibreOffice on Windows (70 nearer,
+  five at most 0.11pt further) and 310 to 301 on Linux; nothing moves down.
 - **A nested list item with no marker stands where the page sets its text in DOCX.** In a
   list of paragraphs — rich items — a nested item was written two spaces a level in, with no
   indent: the project descriptions `Panel`, `Executive`, `ModernProfessional`,

docs/architecture/backend-capability-matrix.md

@@ -62,7 +62,7 @@ Payload records live in `core` under
 
 | Capability (payload) | PDF (fixed) | PPTX (fixed) | DOCX (semantic) |
 |---|---|---|---|
-| Paragraph — pre-wrapped lines, runs, alignment (`ParagraphFragmentPayload`) | ✅ `PdfParagraphFragmentRenderHandler` | ✅ `PptxParagraphFragmentRenderHandler` (one absolute, wrap-disabled frame per measured line) | ⚠️ semantic paragraphs (`DocxSemanticBackend`) — each run keeps its own style, falling back to the paragraph's when it has none; a `linkTarget` becomes a `w:hyperlink`, with a relationship for an address or `w:anchor` for one of the document's own anchors, and a run's own link wins over the paragraph's; a paragraph seated off its baseline (`TextVerticalAlign`) has its runs raised or lowered in the line (`w:position`) by the PDF backend's own correction (`ParagraphSeating`), one shift for the paragraph where the page seats each line by its own; Word and LibreOffice stand an exact line's baseline four fifths of the way down it whatever the face, where the page sets it the face's ascent down, so a paragraph whose face puts the two half a point or more apart — Spectral's, not Lato's — has its text moved to the page's baseline in the same position, matched at its middle line (not yet a list item's or a table text cell's; a picture among it moves with it in Word and stays on its own baseline in LibreOffice); lines a container stacks over one another tighter than their face each end halfway between their letters and the next line's (Word draws an exact line's text on screen only inside the line; its PDF export does not cut it), and the last layer of a shape container on one page, where its line runs past the foot, ends at the foot or below its letters; letters two lines share are split halfway so the page does not move, and a stack that holds a picture keeps its lines' own heights; a `bulletOffset` of spaces becomes the paragraph's indent (`w:ind` left, hanging or first line, by `indentStrategy`) in the flow and in cells, not yet over the flow, in an overlay's left-and-right pair or in a header or footer; one with letters in it is not written, its wrapped lines still set after the spaces that cover it |
+| Paragraph — pre-wrapped lines, runs, alignment (`ParagraphFragmentPayload`) | ✅ `PdfParagraphFragmentRenderHandler` | ✅ `PptxParagraphFragmentRenderHandler` (one absolute, wrap-disabled frame per measured line) | ⚠️ semantic paragraphs (`DocxSemanticBackend`) — each run keeps its own style, falling back to the paragraph's when it has none; a centred or right-aligned left-to-right line of its own, of text alone and untracked, that Word sets a point or more wider or narrower at its half-point size has its letters spaced by the difference (`w:spacing`) and its room reckoned from the page's width; a `linkTarget` becomes a `w:hyperlink`, with a relationship for an address or `w:anchor` for one of the document's own anchors, and a run's own link wins over the paragraph's; a paragraph seated off its baseline (`TextVerticalAlign`) has its runs raised or lowered in the line (`w:position`) by the PDF backend's own correction (`ParagraphSeating`), one shift for the paragraph where the page seats each line by its own; Word and LibreOffice stand an exact line's baseline four fifths of the way down it whatever the face, where the page sets it the face's ascent down, so a paragraph whose face puts the two half a point or more apart — Spectral's, not Lato's — has its text moved to the page's baseline in the same position, matched at its middle line (not yet a list item's or a table text cell's; a picture among it moves with it in Word and stays on its own baseline in LibreOffice); lines a container stacks over one another tighter than their face each end halfway between their letters and the next line's (Word draws an exact line's text on screen only inside the line; its PDF export does not cut it), and the last layer of a shape container on one page, where its line runs past the foot, ends at the foot or below its letters; letters two lines share are split halfway so the page does not move, and a stack that holds a picture keeps its lines' own heights; a `bulletOffset` of spaces becomes the paragraph's indent (`w:ind` left, hanging or first line, by `indentStrategy`) in the flow and in cells, not yet over the flow, in an overlay's left-and-right pair or in a header or footer; one with letters in it is not written, its wrapped lines still set after the spaces that cover it |
 | List hanging indent — a marker column and a content column (`ListBuilder.hangingIndent(true)`, `markerGap(...)`) | ✅ marker and content emitted as separate `ParagraphFragmentPayload` fragments at the resolved `markerX` / `contentX` | ✅ the same fragments — the fixed-layout pipeline resolves the geometry before either backend sees it | ⚠️ the top level only. `DocxSemanticBackend` exports a list as a real Word list — `numbering.xml`, `w:numPr` per item, the level carrying the marker — or, with rich items or a drawn marker, as paragraphs; content and nesting are unaffected. With the flag, the top level's marker column is the layout's — the marker's width and `markerGap`, the text and its wrapped lines where the page sets them — where the gap covers what Word may set the marker wider: a picture at its written size, its edges included, or text in the page's face (embedded, or a standard one Word sets in the same widths) grown to its half-point size, half a point clear. A Word list's level then indents and hangs by that column; a list of paragraphs writes the marker, a tab to a stop there, and hangs the item there. Word places content at absolute indents and has no relative-advance primitive, so without the layout's measure the gap could not be honoured; a Word list without the flag that the layout placed and that does not nest takes the page's column too, the spaces the page sets its wrapped lines after, its marker followed by a space (`w:suff`) and an item that wraps measured at Word's half-point size; a list that nests items, a list built as a tree of items (laid out flattened), and a marker the gap does not clear keep the stated column (180 twips, plus 120 per nesting level) — except, in a list of paragraphs, a nested rich item with no marker, which stands where the layout set its text, its measure weighed at Word's half-point sizes, where the layout's items are matched to the list's; a list that nests only such items sets its top level at the page's column too |
 | Inline code/badge chips (`InlineBackground` on text spans) | ✅ `PdfParagraphFragmentRenderHandler` | ✅ `PptxParagraphFragmentRenderHandler` | ⚠️ `DocxSemanticBackend` — the fill becomes the run's own `w:shd`, in a paragraph and in a list item alike, so a badge still reads as a badge. What Word has no way to say is the shape: shading covers the glyph box, so the corner radius and the padding that widens the run on the page are not in the file, and the export records both. A `w:shd` fill is opaque, so a translucent chip is flattened first against what this export wrote underneath it — the paragraph's shading, the cell's, or the page — so the chip agrees with the file it is in, which on a white page is the colour the PDF shows. It stops being translucent, and that is recorded with the rest |
 | Inline images (`ParagraphImageSpan`) | ✅ `PdfParagraphFragmentRenderHandler` | ✅ `PptxParagraphFragmentRenderHandler` | ✅ `DocxSemanticBackend.writeInlinePicture` (a picture in its own run where it sits among the words, at its size, inside the run's or the paragraph's link; raised or lowered by `w:position` to where the page's alignment and `baselineOffset` put it, from the layout's measure of the paragraph's first line — in a list, the list's text on a line as tall as the item's own tallest picture; LibreOffice ignores `w:position` on a picture and stands it on the baseline, so a picture the export draws itself (icon, emoji, shape) that the page raises carries the rise as transparent rows and needs no `w:position`, while one the page lowers stands in LibreOffice higher than on the page by as much as the page lowers it — up to the text's descent for a centred icon as tall as its line; the editor clips a picture to an exact line height, so a paragraph holding a picture that leaves its text — past the ascent or the descent, in Word's placement or on the baseline — has its lines written at least the height the picture reaches, grown by the editor rather than clipped, every line of the paragraph since Word has one line height for it, and each as tall as the editor's font makes it — for 14pt text about 2.5pt taller than the page's in LibreOffice; a picture inside its text in both editors keeps the exact height; a paragraph of one line of text in a Word paragraph of its own, with room above for its pictures' reach, keeps an exact line at the page's height of it, the pictures set in it where the page puts them in Word and what their ink reaches past it taken from the gaps around it, and in LibreOffice a lowered picture there stands higher and loses what passes the line's top; its description is the text it stands for or empty) |

docs/recipes/docx-export.md

@@ -327,8 +327,17 @@ it. In a table cell, where Word draws no text past the cell's left edge, the lef
 gives no more than it has, and the right edge gives the rest, the line moving by that much.
 Any other centred or right-aligned paragraph keeps the page's measure: in one of several
 lines a wider measure takes another word onto a line, and a short line's box already has
-room for it. A list's items, a line pair's line, text over the flow and a header's or
-footer's line keep the page's measure too.
+room for it. A centred or right-aligned paragraph of one line moves its first letter with
+the line's width, so where Word sets a left-to-right one of text alone a point or more wider
+or narrower than the page, its letters are spaced by the difference (`w:spacing`, in
+twentieths of a point, the size left as Word sets it) and its ends stand within a fraction of
+a point of the page's; its room is then reckoned from the page's width, a few hundredths past
+it. A line that carries tracking, or a picture or a shape, is left as it is, and so is its
+room: Word rounds tracking its own way and spaces the last letter too, which the size does
+not tell. So is a difference under a point — measured, `ObsidianInvoice`'s 9.34pt amounts,
+half a point wider by the size alone, came out as wide as the page's in Word. Text typed into
+a spaced line takes the same spacing. A list's items, a line pair's line, text over the flow
+and a header's or footer's line keep the page's measure too.
 
 ## Named styles, so the document can be restyled