5b4: the README's consumer surface

todo.md

@@ -140,31 +140,11 @@ The numbering is the order the work was planned in, not the order it ships.
       `0.1.0` keeps — 3e names three shapes that parse and then refuse — so the release narrows
       that sentence or lists them.
 - [x] **5a — Rename to `@larvit/adf-codec`.**
-- [ ] **5b — The consumer's error surface (`0.1.0`).** A product-owner read of the public surface
-      found the error result legible to the library and opaque to the consumer holding it, and the
-      README documenting no part of it. The sub-items are that read's answers, and they land before
-      5 because §8 freezes the code list at `0.1.0` and 5b4's table is what reads the list before
-      the freeze closes it.
+- [x] **5b — The consumer's error surface.**
   - [x] **5b1 — The error's source position.**
   - [x] **5b2 — The error messages.**
   - [x] **5b3 — The code list and the flavour's gaps.**
-  - [ ] **5b4 — The README's consumer surface.** §8 invites an exhaustive switch on `code` and no
-        code name appears in the README, so it gains a table — code, when it fires, what the
-        consumer does — grouped by direction, over the thirteen names 5b3 settled. Four things a
-        reader who has not opened the code cannot know: raw
-        HTML is core CommonMark and every construct in input is an error until `0.3.0`, which the
-        guarantees' "three carve-outs and one gap" denies and which is the bot and LLM personas'
-        most common failure; `adfToHtml`, `htmlToAdf`, `markdownToHtml` and `htmlToMarkdown` sit
-        unmarked in the code block people copy from, as do the two HTML guarantee bullets, and take
-        a `0.3.0` mark or leave the block; `adfToMarkdown` is partial on valid ADF — a text node
-        holding a carriage return, a link destination no canonical escape spells — which the viewer
-        persona needs told along with
-        what to do about it; and GFM past tables and strikethrough is literal text, task lists
-        taking `:::taskList`. One sentence for the LLM persona: `code` is stable across minors,
-        `message` is free text. The type-level surface freezes at the same moment and gets the same
-        read: what `index.ts` exports and what it withholds, `ParseError` against `ConvertError`
-        where a direction reads a source, and `ConvertFault` staying internal — the README table
-        names the shapes a consumer switches on, so the two audits are one.
+  - [x] **5b4 — The README's consumer surface.**
 - [ ] **6 — The HTML dialect spec (`0.3.0`).** Element-by-element mapping, the `data-*` fidelity
       scheme, the opaque-carry form, and the documented foreign-element set `htmlToAdf` accepts.
 - [ ] **7 — HTML, ship `0.3.0`.** `adfToHtml`, `htmlToAdf`, the composed `markdownToHtml` /