#807: Browse for Themes brings a template's slide master and layouts

Design › Browse for Themes… with a .pptx or .potx now does what PowerPoint
does: the file's first slide master and its layouts replace the master the
current slide uses (a preserved master stays beside it), stretched to this
deck's slide size. Each slide on the old master moves to the new layout with
the same name, else the same kind, and keeps its content as Layout does. One
undo step. A .thmx still brings its theme only.

Reuse Slides' master copy (media, fresh master, layout and shape ids) moves
into reuse::import_master so both commands share it.

Co-Authored-By: Claude Code <noreply@anthropic.com>



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#	modified:   ROADMAP.md
#	modified:   crates/engine/src/cmd/design.rs
#	modified:   crates/engine/src/cmd/reuse.rs
#	modified:   docs/file-format-parity.md
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docs/file-format-parity.md

@@ -22,7 +22,7 @@ PowerPoint opens and saves; Viewer = opens only).
 | `.pptm` / `.potm` / `.ppsm` macro-enabled | Editor | no | no | Should open and keep `vbaProject.bin` without running it | none |
 | `.ppt` / `.pot` / `.pps` 97–2003 binary | Editor | no | no | Owner decision; import only would be enough | none |
 | `.odp` OpenDocument | Editor | no | no | | none |
-| `.thmx` Office theme | Viewer | no | no | Browse for themes is a P2 row | none |
+| `.thmx` Office theme | Viewer | theme only (Design › Browse for Themes…) | no | Browse for Themes takes a `.thmx`'s colours, fonts and effects; a `.pptx` or `.potx` brings its slide master and layouts as well, and slides move to the matching layouts (#807). A `.thmx`'s own master and layouts aren't read yet | `crates/pptx/src/lib.rs` (`import_theme_tests`), `crates/engine/src/cmd/design.rs` (`browse_theme_tests`) |
 | `.deckcraft` native (zip + JSON) | n/a | yes (also `.slidecraft`) | yes | Lossless for the DeckCraft model, forward compatible | `crates/format` tests |
 | PDF | export | no | yes | Slides, notes pages, handouts (1–9); real-text layer with embedded subsets, links, bookmarks. Slide artwork is a raster image at print resolution, not vector | `crates/pdf` tests |
 | Outline `.rtf` / `.txt` | export (RTF), import (outline) | `.txt` outline; `.md` as Markdown (headings are slides, list items bullets) (`slide.fromOutline`) | `.txt` outline | No RTF | engine tests |
@@ -107,6 +107,7 @@ the round trip even though DeckCraft doesn't model it.
 | 2026-10-15 | minor | A `.pptx` slide that can't be read is reported instead of dropped in silence: `file.open` and `file.openBytes` return `lostSlides`, the app shows a message and opens a repaired copy (Save asks for a new name), and `deckcraft-cli` warns on stderr (#203) |
 | 2026-10-16 | minor | PNG slide export with a transparent background (#784) |
 | 2026-10-16 | trivial | A `.ppsx` opened from the command line or the file association starts the slide show (#862) |
+| 2026-10-15 | minor | `.thmx` row: Browse for Themes reads a theme's colours, fonts and effects; a `.pptx`/`.potx` brings its slide master and layouts (#807) |
 | 2026-10-14 | minor | Community PR wave folded: one row each for `.pptx` (seven owned corpus files), outline, 3-D models, embedded fonts, text, effects, 3-D (extrusion sides draw now), SmartArt (written as a diagram) and VBA (tags and custom XML are kept) |
 | 2026-10-12 | minor | SmartArt import lays each shape's text out on its `dsp:txXfrm` text rectangle instead of the shape box |
 | 2026-10-13 | minor | EMF/WMF rectangle clip regions limit later drawing; EMF+ records remain |