Goals judged in order, Goal 7 names no runtime dependencies, file the isAdfDocument result

README.md

@@ -23,7 +23,7 @@ represent.
 
 ## Goals
 
-The most useful ADF conversion library available, by these goals in priority order:
+The most useful ADF conversion library available, judged by these goals, in priority order:
 
 1. **Lossless, and every call returns a result, never a throw.**
 2. **ADF is the hub.**
@@ -31,7 +31,7 @@ The most useful ADF conversion library available, by these goals in priority ord
 4. **Our markdown is CommonMark, extended only where CommonMark has no spelling.**
 5. **No surprises: output reads and edits the way its audience expects.**
 6. **Lossy conversion drops form, never content.**
-7. **Runs in any JavaScript engine, with nothing to install, configure or connect.**
+7. **Runs in any JavaScript engine, with no runtime dependencies and nothing to configure or connect.**
 8. **Fast, and linear in the document's size.**
 9. **Easy to find, and clear at a glance what it does.**
 

todo.md

@@ -8,6 +8,10 @@
   (Goals 3 and 4). A caller names the markdown it hands in: CommonMark, read as its spec says, or
   the lossless flavour, read as `spec/flavour.md` says. Breaking: `MIGRATION.md` says which call a
   caller takes.
+- **45 — Replace `isAdfDocument` with a reader returning `Result<AdfDocument>`.** Goal 1 has every
+  call return a result; the boolean guard is the one export that does not, and it cannot say which
+  branch refused, where `not-an-adf-document`'s message already does. Breaking: `MIGRATION.md`
+  shows the guard's replacement.
 - **40 — Make `markdownToAdf(adfToMarkdown(doc))` deep-equal `doc` for every document it takes.**
   Today it holds for editor-normal documents only: two adjacent text nodes with the same marks
   merge, an empty `attrs`, `marks` or `content` drops, and `-0` reads back `0` — shapes pipelines