diff --git a/spec/E0011-R-specification.md b/spec/E0011-R-specification.md
index 2f75ea4..33c184a 100644
--- a/spec/E0011-R-specification.md
+++ b/spec/E0011-R-specification.md
@@ -348,6 +348,7 @@ reallocates all three. The pin-map changes this requires are `O-100`.
 - `O-111` — Transpiration is assumed at 140 ml/day and is unmeasured; it sets the humidity-tract mass flow. Closed by the first `O-109` measurement.
 - `O-127` — The main tract's 56 m³/h is the fan's free-air figure, not its operating point; owned by `E0012-R-specification.md`, consumed here. Blocks the air-side terms of §2.2 and the flow in §3.
 - `O-128` — `E5` mounts `SP0008`, the same fan as `E2`, and the tract flow cannot be reached by duty alone. `SP0008` delivers 56 m³/h free air against the superseded part's 10.1 m³/h, so holding the §3 tract flow puts the duty near 0.05, an order below where a ball-bearing DC fan turns stably. One of three closes it: a fixed restriction sized so the fan's minimum stable duty yields the §3 flow, intermittent operation at that minimum, or a smaller fan for this tract. The variant question is the same item: `SP0008` carries a duty input and an alarm output only as custom variants, and `T5`'s trip element is that alarm, which the superseded part had as standard. Blocks `T5`, `D13`, `P3`, `P7`'s `E5` term and the `§3.1` range.
+- `O-129` — Humidity tract as a parallel branch off the main tract instead of a tract with its own fan: fed by `E2`, flow set by branch diameter and take-off geometry, humidity still set by `E3`'s current. Deferred to a later iteration; this build brings each regulated variable under control on its own tract first. Closing it needs the branch diameter, the take-off angle, the split at `E2`'s lowest continuous duty, `T5`'s element moved to `E2`, and `D16` and `T11` recomputed at the branch flow. Closes `O-128` if adopted, and amends ADR-0031 d4's element list and ADR-0032 d4.
 - `O-113` — U9 part not selected; `F11`'s fail-to-safe wiring follows from its output behaviour when its outputs are de-asserted. Blocks `F11`.
 - `O-114` — The luminaire's position relative to the grow volume sets 19 W or 32 W of §2.2 day load and decides whether `D10` binds at the wet edge of the band. Owned by A02-LIGHT and the enclosure, consumed here.
 - ~~`O-115`~~ — ~~No governing ADR for cabinet climate conditioning.~~ — closed 2026-09-08 by ADR-0032.