feat(ooxml): edit and save a pptx

CHANGELOG.md

@@ -16,6 +16,10 @@ The release run heads these entries with the version and opens a fresh
 
 ## Unreleased
 
+- A `.pptx` can be edited and saved: every text operation a `.docx` takes, and
+  a save that writes the slide parts back into the package. Its
+  `FileTypeCapabilities` now states `edit` and `save`.
+
 - A text document is edited the way a reader expects: typing, replacing and
   deleting across runs and paragraphs, Enter, Backspace at a paragraph start,
   and a plain-text paste that opens a paragraph per line.

docs/design/document-editing.md

@@ -6,9 +6,8 @@ mode frame in [`editing.md`](editing.md), and the decisions that are its own.
 the sheet view. Text documents, presentations and drawings share this one:
 what it edits is runs and paragraphs, wherever the format puts them.
 
-Status: **the schema and the replay are landing; the browser editor follows.**
-This document is written ahead of the code, and each section says what is in
-and what is not.
+Status: **landed.** The schema, the replay, the browser editor and the pptx
+write side are all in the code; each section says what is in and what is not.
 
 Scope of this work: an edit that spans several runs, a new paragraph, and a
 delete or a replace that reaches across both. Inline formatting (bold, italic,
@@ -274,7 +273,7 @@ reading forward.
 |---|---|---|
 | `.odt`, `.odp`, `.ods`, `.odg` | `odf` | edits and saves today; the new ops land here |
 | `.docx` | `ooxml/text` | edits and saves today; the new ops land here |
-| `.pptx` | `ooxml/presentation` | **read-only today.** It already has `text_set_content` and keeps its slide DOMs resident; what it lacks is `save`, the two flags and the capability row |
+| `.pptx` | `ooxml/presentation` | edits and saves; the same operations over `a:p` / `a:r` |
 | everything else | — | read-only, and says so by decision 7 |
 
 `.odp` needs nothing of its own: a presentation is the same odf `Document` as a
@@ -295,7 +294,7 @@ Each step is a pull request that builds and tests on its own.
 4. **The browser editor.** Owns the DOM mutation, records the ops, and carries
    undo/redo (decisions 6 and 6b). **Landed.**
 5. **pptx writes.** `save`, `is_editable`, `is_savable`, the capability row and
-   the new hooks over `a:p` / `a:r`.
+   the new hooks over `a:p` / `a:r`. **Landed.**
 
 ## What a split does to what is around it
 

src/odr/internal/file_type_table.cpp

@@ -356,7 +356,9 @@ constexpr std::array table{
          .open = true,
          .decrypt = true,
          .translate_html = true,
-         .color_scheme = true}},
+         .color_scheme = true,
+         .edit = true,
+         .save = true}},
     Row{FileType::office_open_xml_workbook,
         "xlsx"sv,
         xlsx_extensions,

src/odr/internal/ooxml/AGENTS.md

@@ -13,8 +13,8 @@ detection**; each is a self-contained module with its own `AGENTS.md`:
 | Module | Format | Editable | Agent doc |
 |---|---|:--:|---|
 | [`text/`](text/) | `.docx` (Word) | text + save | [text/AGENTS.md](text/AGENTS.md) |
-| [`presentation/`](presentation/) | `.pptx` (PowerPoint) | read-only | [presentation/AGENTS.md](presentation/AGENTS.md) |
-| [`spreadsheet/`](spreadsheet/) | `.xlsx` (Excel) | read-only | [spreadsheet/AGENTS.md](spreadsheet/AGENTS.md) |
+| [`presentation/`](presentation/) | `.pptx` (PowerPoint) | text + save | [presentation/AGENTS.md](presentation/AGENTS.md) |
+| [`spreadsheet/`](spreadsheet/) | `.xlsx` (Excel) | cell values + save | [spreadsheet/AGENTS.md](spreadsheet/AGENTS.md) |
 
 ## Shared element model (same as ODF)
 

src/odr/internal/ooxml/ooxml_util.cpp

@@ -9,6 +9,7 @@
 #include <cstddef>
 #include <cstring>
 #include <stdexcept>
+#include <string_view>
 
 namespace odr::internal {
 
@@ -39,10 +40,13 @@ std::optional<FontStyle> font_style_from_value(const char *value) {
 
 xml::NodeSpan ooxml::write_text_nodes(pugi::xml_node parent,
                                       const pugi::xml_node before,
-                                      const std::string &text) {
+                                      const std::string &text,
+                                      const std::string_view prefix) {
   xml::NodeSpan span;
+  const std::string text_tag = std::string(prefix) + ":t";
+  const std::string tab_tag = std::string(prefix) + ":tab";
 
-  const auto insert = [&](const char *name) {
+  const auto insert = [&](const std::string &name) {
     const pugi::xml_node node = before
                                     ? parent.insert_child_before(name, before)
                                     : parent.append_child(name);
@@ -56,7 +60,7 @@ xml::NodeSpan ooxml::write_text_nodes(pugi::xml_node parent,
   // space at either end of a `w:t`, and a lone space is part of a `string`
   // token - so the text says whether one is there, not the token type.
   const auto insert_text = [&](const std::string &token) {
-    pugi::xml_node node = insert("w:t");
+    pugi::xml_node node = insert(text_tag);
     if (token.starts_with(' ') || token.ends_with(' ')) {
       node.append_attribute("xml:space").set_value("preserve");
     }
@@ -75,14 +79,14 @@ xml::NodeSpan ooxml::write_text_nodes(pugi::xml_node parent,
       break;
     case xml::StringToken::Type::tabs:
       for (std::size_t i = 0; i < token.string.size(); ++i) {
-        insert("w:tab");
+        insert(tab_tag);
       }
       break;
     }
   }
 
   if (!span.first) {
-    insert("w:t");
+    insert(text_tag);
   }
   return span;
 }

src/odr/internal/ooxml/ooxml_util.hpp

@@ -28,10 +28,13 @@ class AbsPath;
 
 namespace odr::internal::ooxml {
 
-/// Writes @p text as `w:t` / `w:tab` nodes before @p before, or at the end of
-/// @p parent where that is null. Empty text still gets a node to anchor to.
+/// Writes @p text as `<@p prefix>:t` / `<@p prefix>:tab` nodes before
+/// @p before, or at the end of @p parent where that is null. The prefix is the
+/// whole difference between the two markup languages: `w:` and `a:`. Empty
+/// text still gets a node to anchor to.
 xml::NodeSpan write_text_nodes(pugi::xml_node parent, pugi::xml_node before,
-                               const std::string &text);
+                               const std::string &text,
+                               std::string_view prefix);
 
 std::optional<std::string> read_string_attribute(pugi::xml_attribute);
 std::optional<Color> read_color_attribute(pugi::xml_attribute);

src/odr/internal/ooxml/presentation/AGENTS.md

@@ -2,7 +2,7 @@
 
 The **why**; the feature checklist is in [`README.md`](README.md), the shared
 OOXML mechanics (registry/adapter pattern, OPC relationships, encryption) in
-[`../AGENTS.md`](../AGENTS.md). **Read-only.**
+[`../AGENTS.md`](../AGENTS.md). **Reader + text editor + save.**
 
 **Scope.** Read `ppt/presentation.xml` and each slide's shape tree into the
 abstract model so the generic renderer lays out positioned frames. Paragraphs,
@@ -92,7 +92,16 @@ Coverage is in [`README.md`](README.md). Foundational gaps, roughly by value:
 3. **Table cell styles unresolved.** Tables are wired (grid, spans, covered
    cells, column widths/row heights), but `a:tcPr` (fills, borders, margins)
    is not translated.
-4. **Read-only.** `text_set_content` machinery exists but is dormant
-   (`element_is_editable` → false); wiring edit + save (mirroring docx) is a
-   natural next step.
+4. **Editing is text-content and the structure a text edit needs**, the same
+   surface `.docx` has: set a run's text, put a run beside one, remove an
+   element, and split, merge or insert a paragraph. The dom half is
+   `xml::TreeEditor`, shared with odf and ooxml text — only the tag names
+   differ, and those come from the nodes. No style editing, and no editing of
+   a shape, a picture or a table's furniture.
+
+   `save` re-serialises the slide parts and copies the rest of the package
+   through as bytes, so a part we never parsed survives untouched. The slides
+   are held by their `r:id`, which is how the slide-id list names them, so
+   `save` keeps the other direction — path to `r:id` — to know which part it
+   is writing.
 5. **Listings, comments/annotations** not modelled.

src/odr/internal/ooxml/presentation/README.md

@@ -23,8 +23,8 @@ Roughly ordered by importance.
   - [x] slide background (`p:bg`, inherited from layout / master)
   - [ ] slide master / layout inheritance (beyond theme colors + background)
 - [x] text extraction
-- [ ] edit
-- [ ] save
+- [x] edit (text, and the structure a text edit needs)
+- [x] save
 
 ### Content