Answer prose round 1: the refusal list lives in the error row, the slot rule gives its reason, and stale item citations go

src/adf/document.ts

@@ -65,7 +65,7 @@ export function emptyKeys(held: { attrs?: AdfAttributes; content?: AdfNode[]; ma
   return keys
 }
 
-// A format spells this node as text; anything more rides a carry.
+// No attrs, content or empty marks; a format may spell this node as text, and anything more rides a carry.
 export function isBareText(node: AdfNode): boolean {
   return node.type === 'text' && node.attrs === undefined && node.content === undefined && node.marks?.length !== 0
 }

src/markdown/directive-syntax.ts

@@ -100,7 +100,7 @@ export function readSoleStringAttribute(span: DirectiveSpan, key: string): Read<
   return { value: spelled.decoded }
 }
 
-// What no content slot holds, which the emitter carries instead: an inline directive never spans lines, and CommonMark reads a null character as U+FFFD.
+// No content slot holds a line ending or a null character, which only the text directive spells; the emitter carries such a node.
 export function slotFault(type: string, text: string): ConvertFault | undefined {
   if (/[\n\r]/.test(text)) return { code: 'unspellable-whitespace', message: `the ${type} content slot holds a newline no inline directive spans` }
   return holdsNullCharacter(text) ? unsupportedNodeShape(`the ${type} content slot holds a null character: write the node as !adf:carry`) : undefined

src/markdown/emit/adf-to-markdown.ts

@@ -272,7 +272,7 @@ function emitCodeDirective(node: AdfNode, model: BlockNodeModel, path: ConvertEr
   return success(directivePair(node, opener.value, texts.map((text) => fencedCodeBlock(info, text)).join('\n')))
 }
 
-// The text each fence holds, or `undefined` where a child is no text a fence keeps, which the carry holds instead.
+// The text of each fence, or `undefined` where a child holds what no fence keeps, so the block carry takes the node.
 function fencedTexts(node: AdfNode): string[] | undefined {
   if (node.content === undefined) return ['']
   const texts: string[] = []