diff --git a/src/markdown/portable/block-spelling.ts b/src/markdown/portable/block-spelling.ts
index a67093f..3c624de 100644
--- a/src/markdown/portable/block-spelling.ts
+++ b/src/markdown/portable/block-spelling.ts
@@ -40,7 +40,7 @@ function headed(head: string): (body: BlockText) => BlockText {
 
 function tryTaskList(node: AdfNode, path: ConvertErrorPath, depth: number, writing: Writing): Result<EmittedBlock> {
   const items: PlacedBlock[][] = []
-  // The portable reduction leaves a task list opening with a task, so `item` is set before any child nests in it.
+  // The portable reduction opens every task list with a task, so this empty array is replaced before any block is pushed to it.
   let item: PlacedBlock[] = []
   // A child other than a task nests in the task before it.
   for (const [index, child] of nodeContent(node).entries()) {
diff --git a/todo.md b/todo.md
index 05cab4d..94a4d57 100644
--- a/todo.md
+++ b/todo.md
@@ -13,7 +13,7 @@
 | ID | Release | Blocked by | Exempt | Item | L | E | I | R | S | Moves | Score |
 |---|---|---|---|---|---|---|---|---|---|---|---|
 | 153 | 0.4.0 |  | question | **Decide whether `src/markdown/` root may import `emit/`, `parse/` or `portable/`, and hold the answer in `.oxlintrc.json` and §The source parts by ADF and format.** | 1 | 2 | 2 | 3 | 2 | code health by 3 | 26.2 |
-| 175 | 0.4.0 |  |  | **Delete the `'a task holds blocks no list item spells'` failure and the child paths in `tryTaskList`, once `spelledList` yields a list the portable reduction can never refuse.** | 1 | 1 | 1 | 1 | 2 | code health by 2 | 17.4 |
+| 175 | 0.4.0 |  |  | **Delete the `'a task holds blocks no list item spells'` failure and the `path` arguments in `tryTaskList`, once `spelledList` can't return `undefined` for a portable task list.** | 1 | 1 | 1 | 1 | 2 | code health by 2 | 17.4 |
 | 176 | 0.4.0 |  |  | **Delete `runEdge`'s `standing === 'moves'` give-up, and any code only it needs, once a test or an argument shows `runEdge` never reaches it, or else pin the case with a hand-worked line.** | 1 | 1 | 2 | 2 | 2 | code health by 2 | 17.4 |
 | 45 | 0.4.0 |  | defect | **Replace `isAdfDocument` with a reader returning `Result<AdfDocument>`.** | 2 | 1 | 3 | 4 | 3 | 1 by 2 | 13.1 |
 | 127 | 0.4.0 |  | principle | **Hold what `entity-references.test.ts`, `json-text.test.ts` and `result.test.ts` check by asserting outcomes, so none reads source text.** | 2 | 2 | 1 | 3 | 3 | code health by 2 | 13.1 |
@@ -72,13 +72,14 @@ a paragraph opening with a spellable `!adf:link` (§Nothing recurses unbounded).
 `src/markdown/**` bans only `html/`; banning `emit/`, `parse/` and `portable/` for the root's own
 files, with its `ci.sh` probe, extends the decision.
 
-### 175. Delete the `'a task holds blocks no list item spells'` failure and the child paths in `tryTaskList`, once `spelledList` yields a list the portable reduction can never refuse.
+### 175. Delete the `'a task holds blocks no list item spells'` failure and the `path` arguments in `tryTaskList`, once `spelledList` can't return `undefined` for a portable task list.
 
-`reduceToPortable` runs first, so `adfToPortableMarkdown` never reaches `tryTaskList`'s
-(`portable/block-spelling.ts`) failure; no test reaches it either. It stays because `spelledList`
-returns `undefined` for the blocks a list item cannot hold, and the type has no cast to drop it.
-The `path` it passes to `taskBlocks` and `placedBlock` changes no output, since the nesting
-refusal's path comes from `reduceToPortable`. Found by mutation testing for item 128, 2026-11-08.
+`reduceToPortable` runs first, so `adfToPortableMarkdown` never reaches the failure in `tryTaskList`
+(`portable/block-spelling.ts`), and no test reaches it. The failure stays because `spelledList`
+returns `undefined` for blocks a list item cannot hold, and the code rules ban the cast that would
+drop that case. The `path` arguments to `taskBlocks` and `placedBlock` don't change any output:
+`reduceToPortable` refuses a document nested past `largestNesting` and names the path itself.
+Found by mutation testing for item 128, 2026-11-08.
 
 ### 176. Delete `runEdge`'s `standing === 'moves'` give-up, and any code only it needs, once a test or an argument shows `runEdge` never reaches it, or else pin the case with a hand-worked line.