Tick 4.3 and 4, moving their text to todo-history.md

todo.md

@@ -43,36 +43,10 @@ proves 12, 13 spells 11's gaps in 12's grammar, and 12 rewrites code 4b and 4c c
   - [x] **3i — The inline nodes and the marks.**
   - [x] **3j — The carry and the combinations.**
   - [x] **3k — The CommonMark spec suite.**
-- [ ] **4 — Round-trip property tests (`0.2.0`)**, widening 3j's corpus round-trip past the
-      documents a human wrote — the thing that proves 2 and 3 beyond them.
-      **Settled** (the maintainer, 2026-09-13): `fast-check` generates and shrinks. The gate runs a
-      fixed seed, the properties together adding about five seconds per engine; an environment
-      variable raises the runs and randomizes the seed for local digging, and a counterexample
-      found becomes a round-trip fixture. The generators draw from the node tables — each node's
-      content model and attribute vocabulary as `adf/` records them, which 11 holds to Atlassian's
-      schema — and misplace a share of nodes so the carry (§3) is exercised; no JSON Schema walker
-      enters the tests. `toEditorNormal` stays internal. 2e5's collision test goes, since a
-      collision already fails the round-trip on the same fixtures; the fixture-duplicate test
-      stays.
+- [x] **4 — Round-trip property tests.**
   - [x] **4.1 — Editor-normal and the node accessors.**
   - [x] **4.2 — The ADF property.**
-  - [ ] **4.3 — The markdown property.** Generated markdown through `markdownToAdf` never throws,
-        and the runs fit the budget; where it parses and `adfToMarkdown` spells the result, that
-        spelling parses and emits to itself byte for byte (§2).
-        **Settled** (the maintainer, 2026-09-15): the generators and run parameters 4.2 and 4.3
-        share live in one test-only module in `src/`, kept out of the build and coverage, with
-        10c's properties as its third user. Under the gate seed the property asserts floors on the
-        runs reaching the fixpoint and on the directive-shaped ones. It lands when hunts of several
-        hundred thousand runs per engine pass clean, since the breaks hit once per ~150,000 runs,
-        past a 10,000-run bar. Two breaks, both shipped in `0.1.0`, are fixed inside it. A backtick
-        string an escape formed closed an earlier bare run's code span, since CommonMark reads no
-        escape inside one: an escaped backtick alone or, as the review found, one joined to the bare
-        run after it. A backtick run now escapes whole, and a bare run escapes wherever a later
-        string of its length forms around an escape in the same inline content: the generalized pass
-        the maintainer chose (2026-09-15). A paragraph's opening read as a link
-        reference definition across a `]` the emitter spelled: the emitter now escapes the opening
-        `[` exactly when the parser's own definition reader accepts the paragraph, and a link
-        opening it rides the carry until 13b.
+  - [x] **4.3 — The markdown property.**
   - [x] **4.4 — The real payloads.**
 - [ ] **4b — The block walk's retry (`0.2.0`).** `emitBlock` walks a subtree twice wherever
       `readableBlock` reads it whole and then gives up — a list item whose first line reads back