docs(train): Health Connect before the Loop (ADR 0030, D29)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Tizian 「ティツィアーン」 <raisondetredev@pm.me>

docs/adr/0030-halkyon-train.md

@@ -1,7 +1,8 @@
 # ADR 0030: Halkyon Train, what it does and where its data comes from
 
-- **Status:** decided 27–28 Oct 2026, by the developer (D1–D28 below). The shell (D12)
-  is built; recording (D13–D24) is being built.
+- **Status:** decided 27–28 Oct 2026, by the developer (D1–D29 below). The shell (D12)
+  is built; recording (D13–D28) is built on Android, iOS waiting for a Mac; Health
+  Connect (D29) comes next.
 - **Numbering:** 0025 is held by the federation draft (stashed), 0026–0029 by the .NET
   rewrite on the local branch `rewrite-dotnet`, abandoned on 27 Oct; Train takes the next
   free number so that neither is ever read as this one.
@@ -461,6 +462,18 @@ Strava. What was found, 27 Oct:
   not read yet, the strokes deciding the pause; the notification shows a row's
   distance in kilometres, as the others'. Not yet tried on the WP 5000.
 
+## After recording (28 Oct 2026, the developer's)
+
+- **D29 Health Connect next, the Loop after it** (recommended, the developer's; over the
+  Loop first, and over neither before the intervals): Health Connect is the smaller
+  piece and serves every workout Train records already; writing gives them to every
+  other app on the phone, reading brings what Train can't speak to itself (Gadgetbridge's
+  watches and rings, Christopeit Connect's rows), and the Loop's sessions can later go
+  there the same way. The Loop needs Polar's SDK, its first-time setup and D10's
+  firmware, and new kinds of data (daily activity, sleep, 24/7 heart rate, Nightly
+  Recharge) with synced models of their own; it is tried only with the band at hand.
+  The intervals (D2) need neither.
+
 ## Consequences
 
 - Train's sensors are one pattern: open profiles read by the app itself, on the phone;