From 92ce4ba2aef70967a5e9f0ab927b00668fd07873 Mon Sep 17 00:00:00 2001
From: Duncan Tourolle <duncan@tourolle.paris>
Date: Thu, 27 Aug 2026 18:04:16 +0200
Subject: [PATCH] Refuse to join the pair, rather than undoing it a second
 later
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Connecting both pods is the configuration in which the `−` pod stops
reporting its own paddle (§2.3.1). `Cmd::Seen` has always known that and
declined; an explicit `Cmd::Connect` walked straight past it, and
housekeeping then closed the redundant link a second or so later — which
looks like the app handling the case and is not the same thing. On the
tablet, 2026-08-27 15:55:39, the pair was joined for 1.4 s and the `−`
pod did not report another press for the rest of the session, across two
fresh links and an app reinstall.

So the rule now lives on both paths. `auto` is still armed by the refused
request, so the fallback stands: the moment the `−` pod goes away, the
`+` pod is taken on its next advertisement.

And the UI stops offering the trap. The `+` pod's "Connect anyway" sat
next to a working controller, which put the one action that breaks
shifting a single tap from a rider hunting for a way to fix shifting. It
now reads "Held in reserve", which is what that pod is.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
---
 src-tauri/src/controller.rs         | 26 ++++++++++++++++++++++++++
 src-tauri/tauri.conf.json           |  4 ++--
 ui/src/components/ClickPanel.svelte | 17 ++++++++++++++---
 3 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/src-tauri/src/controller.rs b/src-tauri/src/controller.rs
index b496f1d..d8e9408 100644
--- a/src-tauri/src/controller.rs
+++ b/src-tauri/src/controller.rs
@@ -646,10 +646,36 @@ async fn run(
                 };
                 match cmd {
                     Cmd::Connect { pod, address } => {
+                        // The rule `Cmd::Seen` has always enforced, applied
+                        // here too: with the `−` pod up there is nothing for a
+                        // `+` link to add and one specific thing for it to
+                        // break — connected as a pair, the `−` pod stops
+                        // reporting its own paddle (§2.3.1).
+                        //
+                        // Only the scan-driven path was guarded, so an explicit
+                        // request walked straight past it. Housekeeping then
+                        // closed the redundant link a second or so later, which
+                        // reads as the app handling it and is not the same
+                        // thing at all: on the tablet, 2026-08-27 15:55:39, the
+                        // pair was joined for 1.4 s and the `−` pod did not
+                        // report a press again for the rest of the session.
+                        //
+                        // `auto` is still armed below, so the fallback stands:
+                        // the moment the `−` pod goes away, the `+` pod is
+                        // taken on its next advertisement.
+                        let minus_up = !minus.idle();
                         let slot = slot_mut(&mut minus, &mut plus, pod);
                         // Asking for it by hand re-arms auto-connect, whatever
                         // came before.
                         slot.auto = true;
+                        if pod == PodId::Plus && minus_up {
+                            tracing::info!(
+                                "controller: refusing a + pod link while the − pod is up — \
+                                 it relays the pair, and joining both stops it reporting \
+                                 its own paddle"
+                            );
+                            continue;
+                        }
                         // A second click while a search is running means
                         // "connect", which is what is already happening.
                         if slot.connecting() {
diff --git a/src-tauri/tauri.conf.json b/src-tauri/tauri.conf.json
index 1d4dc3c..b94d860 100644
--- a/src-tauri/tauri.conf.json
+++ b/src-tauri/tauri.conf.json
@@ -1,7 +1,7 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
   "productName": "BikeControl",
-  "version": "0.2.4",
+  "version": "0.2.5",
   "identifier": "paris.tourolle.bikecontrol",
   "build": {
     "frontendDist": "../ui/dist",
@@ -43,7 +43,7 @@
     ],
     "category": "Utility",
     "android": {
-      "versionCode": 1204
+      "versionCode": 1205
     },
     "shortDescription": "Indoor cycling trainer control",
     "longDescription": "Control a smart trainer over BLE, ride gradient profiles and synthetic waveforms, and record the result."
diff --git a/ui/src/components/ClickPanel.svelte b/ui/src/components/ClickPanel.svelte
index c939335..d97e2ed 100644
--- a/ui/src/components/ClickPanel.svelte
+++ b/ui/src/components/ClickPanel.svelte
@@ -158,10 +158,15 @@
             <button class="btn ghost" onclick={() => disconnect(pod.pod)}>Disconnect</button>
           {:else if pod.state === 'searching'}
             <button class="btn ghost" onclick={() => disconnect(pod.pod)}>Stop</button>
+          {:else if dormant}
+            <!-- No "connect anyway". Joining the pair is the one action that
+                 stops the − pod reporting its own paddle (§2.3.1), and offering
+                 it beside a working controller put the failure one tap from a
+                 rider hunting for a fix. Rust refuses it too. The fallback is
+                 not lost: the moment the − pod goes, this pod is taken. -->
+            <span class="held">Held in reserve</span>
           {:else}
-            <button class="btn ghost" onclick={() => connect(pod.pod)}>
-              {dormant ? 'Connect anyway' : 'Find it'}
-            </button>
+            <button class="btn ghost" onclick={() => connect(pod.pod)}>Find it</button>
           {/if}
         </div>
 
@@ -353,6 +358,12 @@
     font-size: 0.82rem;
   }
 
+  .held {
+    align-self: center;
+    font-size: 0.8rem;
+    color: var(--ink-faint);
+  }
+
   .note {
     flex: 1 1 100%;
     margin: 0;