diff --git a/src/markdown/emit/adf-to-markdown.test.ts b/src/markdown/emit/adf-to-markdown.test.ts
index 7b138c0..f0cf278 100644
--- a/src/markdown/emit/adf-to-markdown.test.ts
+++ b/src/markdown/emit/adf-to-markdown.test.ts
@@ -49,6 +49,16 @@ test('refuses a node whose carry nests too deep ahead of a later node in its lin
   assert.deepEqual(path(refused), ['content', 0, 'content', 0])
 })
 
+test('refuses a carried run at the node whose carry nests too deep, among the run\'s own nodes', () => {
+  let deep: JsonValue = 'a'
+  for (let depth = 0; depth < largestNesting - 1; depth += 1) deep = { deep }
+  const carriedEm: AdfNode = { marks: [{ attrs: { deep }, type: 'em' }], text: 'x', type: 'text' }
+  const twiceStrong: AdfNode = { marks: [{ type: 'strong' }, { type: 'strong' }], text: 'y', type: 'text' }
+  const refused = adfToLosslessMarkdown(document(paragraph({ text: 'ok', type: 'text' }, carriedEm, twiceStrong)))
+  assert.equal(code(refused), 'unsupported-nesting-depth')
+  assert.deepEqual(path(refused), ['content', 0, 'content', 1])
+})
+
 test('refuses a value that is not an ADF document, naming the check it failed', () => {
   assert.equal(markdown(adfToLosslessMarkdown({ type: 'doc', version: Number.NaN })), 'not-an-adf-document: an ADF document holds a version number: found NaN')
 })
diff --git a/src/markdown/emit/inline-line.ts b/src/markdown/emit/inline-line.ts
index 5b02f79..5d7abe4 100644
--- a/src/markdown/emit/inline-line.ts
+++ b/src/markdown/emit/inline-line.ts
@@ -234,13 +234,15 @@ function inlineRuns(nodes: readonly RunNode[], firstIndex: number, carried: Read
   for (const [offset, runNode] of nodes.entries()) {
     const index = firstIndex + offset
     const { node, outer } = runNode
-    const previous = runs[runs.length - 1]
     // A carried node spells its marks inside the carry.
-    const carriedNode = carries(node, carried, index)
-    const inside = carriedNode || previous?.kind !== 'marked' ? undefined : insideRun(runNode, previous.mark)
-    const mark = carriedNode ? undefined : nodeMarks(node)[outer]
+    const mark = carries(node, carried, index) ? undefined : nodeMarks(node)[outer]
+    if (mark === undefined) {
+      runs.push({ index, kind: 'plain', node })
+      continue
+    }
+    const previous = runs[runs.length - 1]
+    const inside = previous?.kind === 'marked' ? insideRun(runNode, previous.mark) : undefined
     if (previous?.kind === 'marked' && inside !== undefined) previous.nodes.push(inside)
-    else if (mark === undefined) runs.push({ index, kind: 'plain', node })
     else runs.push({ index, kind: 'marked', mark, nodes: [{ node, outer: outer + 1 }] })
   }
   return runs
diff --git a/src/markdown/portable/adf-to-portable-markdown.test.ts b/src/markdown/portable/adf-to-portable-markdown.test.ts
index 4b0f3c5..5deef9c 100644
--- a/src/markdown/portable/adf-to-portable-markdown.test.ts
+++ b/src/markdown/portable/adf-to-portable-markdown.test.ts
@@ -465,6 +465,11 @@ test('writes what the editor-normal form of the document writes', () => {
   assert.equal(portable(paragraph({ marks: [{ attrs: {}, type: 'code' }], text: 'a', type: 'text' }, { marks: [{ type: 'code' }], text: '|b', type: 'text' })), '`a|b`\n')
 })
 
+test('keeps the code mark of a node past an opening link when the fallback drops the link\'s own', () => {
+  const link: AdfMark = { attrs: { href: 'u' }, type: 'link' }
+  assert.equal(portable(paragraph(text('x]: y', link, code), text('z', code))), '[x\\]: y](u)`z`\n')
+})
+
 test('writes a text node holding content the same in either order beside its neighbour', () => {
   const holding: AdfNode = { content: [text('inner')], text: 'a', type: 'text' }
   assert.equal(portable(paragraph(holding, text('b'))), 'ab\n')
diff --git a/src/markdown/portable/editor-normal.ts b/src/markdown/portable/editor-normal.ts
index f9ad390..aa88f1a 100644
--- a/src/markdown/portable/editor-normal.ts
+++ b/src/markdown/portable/editor-normal.ts
@@ -1,6 +1,6 @@
 import type { AdfAttributes, AdfDocument, AdfMark, AdfNode } from '../../adf/document.ts'
 import type { JsonValue } from '../../json-value.ts'
-import { identicalMark, mergeAdjacentText, nodeAttrs, nodeContent, nodeMarks } from '../../adf/document.ts'
+import { mergeAdjacentText, nodeAttrs, nodeContent, nodeMarks } from '../../adf/document.ts'
 import { joinsWhenRead } from '../adjacent-text.ts'
 
 type JsonContainer = JsonValue[] | { [key: string]: JsonValue }
@@ -13,10 +13,6 @@ export function joinsWhenEditorNormal(previous: AdfNode, node: AdfNode): boolean
   return joinsWhenRead(normalNode(previous), normalNode(node))
 }
 
-export function sameMarkWhenEditorNormal(left: AdfMark, right: AdfMark): boolean {
-  return identicalMark(normalMark(left), normalMark(right))
-}
-
 export function toEditorNormal(document: AdfDocument): AdfDocument {
   const normal: AdfDocument = { type: document.type, version: Object.is(document.version, -0) ? 0 : document.version }
   const pending: { holder: NodeHolder; source: NodeHolder }[] = [{ holder: normal, source: document }]
diff --git a/src/markdown/portable/inline-reduction.test.ts b/src/markdown/portable/inline-reduction.test.ts
index cb7843a..924bf03 100644
--- a/src/markdown/portable/inline-reduction.test.ts
+++ b/src/markdown/portable/inline-reduction.test.ts
@@ -37,6 +37,30 @@ test('reduces a line alike dropping every run a pass may or the first alone', ()
 })
 
 // Drops only the first run each pass finds, with every misflanked highlight, and takes no cap.
+test('refuses an opening-link fallback whose link run holds no code span', () => {
+  const link = { attrs: { href: 'u' }, type: 'link' }
+  const lines: AdfNode[][] = [
+    [{ marks: [link], text: 'a', type: 'text' }],
+    [{ marks: [link, { type: 'em' }], text: 'a', type: 'text' }],
+    [{ marks: [link], text: 'a', type: 'text' }, { marks: [{ type: 'code' }], text: 'c', type: 'text' }],
+  ]
+  for (const line of lines) {
+    const refused = withoutFallback(line, { kind: 'opening-link' }, [])
+    assert.equal(refused.ok ? 'kept' : refused.error.code, 'unsupported-node-shape')
+  }
+})
+
+test('takes code off every node of an opening link\'s run that an opening-link fallback names', () => {
+  const link = { attrs: { href: 'u' }, type: 'link' }
+  const line: AdfNode[] = [{ marks: [link, { type: 'code' }], text: 'a', type: 'text' }, { marks: [link], text: 'b', type: 'text' }]
+  assert.deepEqual(withoutFallback(line, { kind: 'opening-link' }, []), success([{ marks: [link], text: 'a', type: 'text' }, { marks: [link], text: 'b', type: 'text' }]))
+})
+
+test('refuses an unspellable-run fallback that takes no mark', () => {
+  const refused = withoutFallback([{ marks: [{ type: 'em' }], text: 'a', type: 'text' }], { kind: 'unspellable-run', runs: [{ depth: 1, first: 0, last: 0 }] }, [])
+  assert.equal(refused.ok ? 'kept' : refused.error.code, 'unsupported-node-shape')
+})
+
 function firstRunLine(nodes: readonly AdfNode[], container: LineContainer): Result<AdfNode[]> {
   const leaves = portableLeaves(nodes, container, [], 0)
   if (!leaves.ok) return leaves
diff --git a/src/markdown/portable/inline-reduction.ts b/src/markdown/portable/inline-reduction.ts
index 055f51f..d76db68 100644
--- a/src/markdown/portable/inline-reduction.ts
+++ b/src/markdown/portable/inline-reduction.ts
@@ -3,11 +3,11 @@ import type { LineContainer } from '../line-container.ts'
 import type { MarkRun } from '../emit/line-escaping.ts'
 import { codeTextMarkTypes } from '../../adf/inline-nodes.ts'
 import { failure, success, type ConvertErrorPath, type Result } from '../../result.ts'
+import { identicalMark, mergeAdjacentText, nodeAttrs, nodeContent, nodeMarks } from '../../adf/document.ts'
 import { imageAside } from '../image-aside.ts'
 import { insideRun, isEmphasis, type RunNode } from '../mark-spellings.ts'
-import { joinsWhenEditorNormal, sameMarkWhenEditorNormal } from './editor-normal.ts'
+import { joinsWhenEditorNormal } from './editor-normal.ts'
 import { largestNesting } from '../../nesting.ts'
-import { mergeAdjacentText, nodeAttrs, nodeContent, nodeMarks } from '../../adf/document.ts'
 import { partsShownText, referenceName, shownImage, shownLink, shownText, shownUrl } from '../../adf/shown-text.ts'
 import { portableLineFallback, readBackPasses, type PortableLineFallback } from '../emit/inline-line.ts'
 import { spellDestination } from '../commonmark/link-syntax.ts'
@@ -145,11 +145,11 @@ function highlightsInsideSharedMarks(leaves: readonly AdfNode[]): AdfNode[] {
     const marks = nodeMarks(leaf)
     if (marks[0]?.type === highlight) {
       const held = marks.slice(1)
-      shared = run.length === 0 ? held : shared.filter((mark) => held.some((other) => sameMarkWhenEditorNormal(other, mark)))
+      shared = run.length === 0 ? held : shared.filter((mark) => held.some((other) => identicalMark(other, mark)))
       run.push(leaf)
       continue
     }
-    for (const held of run) spelled.push(withMarks(held, [...shared, highlightMark, ...nodeMarks(held).slice(1).filter((mark) => !shared.some((other) => sameMarkWhenEditorNormal(other, mark)))]))
+    for (const held of run) spelled.push(withMarks(held, [...shared, highlightMark, ...nodeMarks(held).slice(1).filter((mark) => !shared.some((other) => identicalMark(other, mark)))]))
     run = []
     spelled.push(leaf)
   }
@@ -229,7 +229,7 @@ function sharedRuns(marks: readonly AdfMark[], neighbour: AdfNode): number {
 }
 
 function spellableLine(leaves: AdfNode[], container: LineContainer, path: ConvertErrorPath): Result<AdfNode[]> {
-  // Terminates: each fallback takes a mark off some leaf, and trimmedEdges adds none to any character.
+  // Terminates: withoutFallback refuses a pass that takes no mark, and trimmedEdges adds none to any character.
   for (let current = leaves, pass = 1; ; pass += 1) {
     const fallback = portableLineFallback(current, container, path)
     if (!fallback.ok) return fallback
@@ -260,7 +260,7 @@ function withoutEmphasis(leaves: readonly AdfNode[]): AdfNode[] {
 }
 
 // The runs one pass takes back may nest, so a leaf drops its mark at each depth a run over it names.
-function withoutMarks(leaves: readonly AdfNode[], runs: readonly MarkRun[]): AdfNode[] {
+function withoutMarks(leaves: readonly AdfNode[], runs: readonly MarkRun[]): AdfNode[] | undefined {
   const depths = new Map<number, number[]>()
   for (const run of runs) {
     for (let index = run.first; index <= run.last; index += 1) {
@@ -269,8 +269,13 @@ function withoutMarks(leaves: readonly AdfNode[], runs: readonly MarkRun[]): Adf
       else held.push(run.depth)
     }
   }
-  return leaves.map((leaf, index) => {
+  const kept = leaves.map((leaf, index) => {
     const dropped = depths.get(index)
     return dropped === undefined ? leaf : withMarks(leaf, nodeMarks(leaf).filter((_, held) => !dropped.includes(held)))
   })
+  return markCount(kept) < markCount(leaves) ? kept : undefined
+}
+
+function markCount(leaves: readonly AdfNode[]): number {
+  return leaves.reduce((count, leaf) => count + nodeMarks(leaf).length, 0)
 }
diff --git a/todo.md b/todo.md
index 3df9f59..1057565 100644
--- a/todo.md
+++ b/todo.md
@@ -81,6 +81,8 @@ mention or code spelled `!adf:text{text=" "}`. Joining the run across the break
 `inline-line.ts` ruled worse with two comprehension panels (PR #22): a joined run that cannot be spelled needs its own fallback,
 first as a set of parted breaks, then as a flag the first fallback clears.
 
+Once a run spans a node that doesn't hold its mark, `outer` and `depth` differ. Settle which one `tryLink`'s `depth + 1` and `MarkRun.depth` mean, and keep `MarkRun.depth`'s comment true.
+
 ### 133. Write mentions, emoji, dates, statuses and inline cards as semantic HTML in `adfToHtml` and read them back in `htmlToAdf`, in place of the carry element.
 
 A writer panel picks the elements, classes and `data-*` attributes. Where a link marks a card, both