Record the toggle/dropdown default-over-init divergence

Found while running the store screenshot capture on iOS (plan phase 4): the
tone-generator scene, which sets `channels` and `advanced` as element defaults
because that is what Android obeys, came out with one channel on iOS, because
there the container's `init` wins.

The spec already settles which is right - the remark on `default` says it
applies only while the buffer is EMPTY and never over a value in it - and iOS
implements exactly that. Android's toggle and dropdown build their widget from
`defaultValue` with `triggered` already set, so the first write pass clears the
buffer and appends the widget's value over whatever `init` put there; the
`seedIfEmpty()` path added for this in 93a31966 is simply reached too late.
`edit` destroys the init value on that pass too, by writing NaN.

So: one entry, status decided with the canonical behaviour quoted from the
spec, and `agreement: divergent` on the three attributes it covers. The fix
belongs to Android and is written up in the working root's Android-TODO.md.

Until then the tone-generator scene says both spellings, identically, which is
the only thing that produces that picture on both platforms.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: Staacks

inconsistencies.yml

@@ -89,3 +89,51 @@
     A non-power-of-two number of input samples yields a different output
     length and different values on the two platforms; a power-of-two input
     gives identical results on both.
+
+- id: toggle-dropdown-default-overwrites-init
+  title: A toggle's or dropdown's default against the container's init
+  area: file-format
+  status: decided
+  canonical: >-
+    The spec already states it, in the remark on the default attribute of
+    edit, toggle, dropdown and slider: a default is applied whenever the
+    buffer is EMPTY, and never over a value that is in it. A container's
+    init therefore wins over a control's default, and an author who writes
+    both is asking for the init value.
+  affects:
+    android: >-
+      toggle and dropdown overwrite the container regardless. Both start with
+      their trigger flag set (ExpView.java, toggleElement line 3093 and
+      dropDownElement line 3244) and build their widget showing defaultValue,
+      so the first onMayWriteToBuffers pass after the view exists does
+      clear(false) + append(<what the widget shows>) over whatever init put
+      there (lines 3176-3183 and 3397-3401). The conditional seedIfEmpty()
+      right above it (lines 305-313), added in 93a31966 with the message
+      "never over a value somebody set", is the intended path and is the one
+      the spec describes - it is simply reached too late to matter. edit is a
+      third case again: it writes NaN over the init value on that same first
+      pass and only picks its default up on the next one.
+    ios: >-
+      Follows the spec. Experiment.seedInputDefaults() writes an input
+      element's default only into a buffer whose last value is nil, at load
+      and at the start of each analysis cycle, and the view modules write
+      nothing until the user touches them (ExperimentSwitchView.setState,
+      ExperimentDropdownView, ExperimentEditView). A container with init
+      keeps its value.
+  verified: >-
+    Observed on both platforms with the same file, the store screenshot
+    system's tone-generator scene (phyphox-docs/screenshots/scenes.yml), which
+    wants two channels with the advanced controls shown. On Android
+    (2026-08-31, API 36 emulator) setting only the containers' init produced
+    one channel and no advanced controls, i.e. the element defaults won; on
+    iOS (2026-09-01, iPhone 17 Pro Max simulator, Release build of
+    development) setting only the element defaults produced the same picture,
+    i.e. the init values won. The scene now sets both, identically, which is
+    the only spelling that works on both.
+  summary: >-
+    An input control's default attribute and its container's init attribute
+    disagree about which one an experiment starts with. The spec says init
+    wins - a default fills an empty buffer and never overwrites one - which is
+    what iOS does; on Android a toggle or dropdown writes its own default over
+    the container on the first pass after its view is built, so the same file
+    starts in two different states.

screenshots/scenes.yml

@@ -146,13 +146,26 @@ scenes:
     init:
       f1: [440]
       f2: [660]
+      # Deliberately the same two values again, as containers, because the two
+      # apps do not agree on which of the two a control obeys (see
+      # docs/reference/known-inconsistencies.md, `toggle-dropdown-default-
+      # overwrites-init`). The spec's rule - a `default` applies only while the
+      # buffer is EMPTY - is what iOS does, so there `init` alone would be
+      # enough; Android's toggle and dropdown write their `default` over the
+      # container on the first pass after the view is built, so there `default`
+      # alone is what works. Saying both, identically, is the only spelling
+      # that produces this scene on both platforms today and stays correct once
+      # Android is fixed.
+      channels: [2]
+      advanced: [1]
     note: >-
       Two channels with the advanced controls shown, on the first tab. The
-      channel count and the advanced switch are set as element DEFAULTS, not as
-      container init values: both are written by controls in the Settings view
+      channel count and the advanced switch are written both as element
+      DEFAULTS and as container init values, because the two apps disagree
+      about which of those a control obeys at load (see the comment above the
+      values). Both are controls in the Settings view
       (`<dropdown label="Channels" default="1">` and
-      `<toggle label="Advanced" default="0">`), and a control writes its own
-      default over the container when the experiment loads. c2 and c2advanced
+      `<toggle label="Advanced" default="0">`). c2 and c2advanced
       are then derived by the file's own analysis (`channels > 1`, and
       c2 * advanced), which is what makes the extra controls visible.
 

spec/views.yml

@@ -917,7 +917,8 @@ elements:
           with clearGroup on the data container, which is what it is for.
         default: 0.0
         summary: Value the field starts with.
-        agreement: agreed
+        agreement: divergent
+        inconsistency: toggle-dropdown-default-overwrites-init
   - name: output
     parent: edit
     since: "1.0"
@@ -1030,7 +1031,8 @@ elements:
           with clearGroup on the data container, which is what it is for.
         default: 0.0
         summary: State the switch starts in.
-        agreement: agreed
+        agreement: divergent
+        inconsistency: toggle-dropdown-default-overwrites-init
 
   - name: output
     parent: toggle
@@ -1164,7 +1166,8 @@ elements:
           with clearGroup on the data container, which is what it is for.
         default: 0.0
         summary: Value selected initially.
-        agreement: agreed
+        agreement: divergent
+        inconsistency: toggle-dropdown-default-overwrites-init
       - name: color
         type: color
         rules: [color-invalid-value]