Slider custom fields

CHANGELOG.md

@@ -8,13 +8,34 @@ uses semantic versioning (`MAJOR.MINOR.PATCH`).
 
 ### Added
 
+- **Slider custom fields.** A field can now be a slider, matching the type the
+  server and the web app gained: either a labelled one from 0 to 100 between
+  two words of your choosing ("Drained" to "Wired", read as a percentage), or a
+  number with its own range, step and unit ("172.5 cm"). Either can paint a
+  colour gradient across the track, picked from nine named ones or built from
+  your own colours with the colour picker the app already uses for members and
+  tags. Settings gets the whole setup with a live preview; the member editor
+  gets a draggable track with the reading beside it and a tap to clear; a
+  member's profile shows the reading. The reading is the same string the server
+  puts on a public profile, so a slider reads the same everywhere.
+
 - **Announcements can be aimed at particular clients.** Admin only. An
   announcement can now be shown only on Web, Android, iOS or the watch, with a
   "Show on" section in the editor and a marker in the list; leaving it unticked
   shows it to everyone, as before. The app also names itself when asking, so an
   announcement aimed at Android reaches it. Needs a server that supports
   targeting; on an older one everything carries on as it was.
 
+### Fixed
+
+- **A field type this build has not heard of no longer reads as an error.** A
+  custom field whose type the server knows and the app does not showed "Unknown
+  field type" in red where its value should be, so the value a member had put
+  there was hidden by a message that looked like a fault. It now shows the value
+  as text with a note to update the app, which is what the API asks clients to
+  do, and is why a slider field on an older build will have looked broken rather
+  than merely unsupported.
+
 ## [1.5.0] - 2026-10-12
 
 ### Added

sheaf/app/src/main/java/systems/lupine/sheaf/data/model/Models.kt

@@ -804,15 +804,43 @@ data class TagDeletePending(
 
 // ── Custom Fields ─────────────────────────────────────────────────────────────
 
+/** The two ends of a slider, and optionally its middle. Each up to 50 chars. */
+@JsonClass(generateAdapter = true)
+data class SliderLabels(
+    val left: String? = null,
+    val center: String? = null,
+    val right: String? = null,
+)
+
 /**
  * Per-field-type options. For SELECT / MULTISELECT, [choices] carries
  * the predefined values the user can pick from; null = freeform tag
- * mode (any string accepted server-side). Other field types don't
- * carry options today.
+ * mode (any string accepted server-side).
+ *
+ * The rest belong to SLIDER, which the server always stores in full canonical
+ * shape, so every key below comes back populated on a read. On a write the
+ * rules are the opposite of the PATCH bodies next door: the server rebuilds a
+ * slider's options from scratch rather than merging, so a key left out means
+ * "the default for that key", not "leave it alone". Moshi omitting nulls is
+ * therefore exactly right here, and it is what clears a label, a unit or a
+ * gradient. Do not reach for a hand-written adapter: it would send explicit
+ * nulls, which say the same thing, less clearly.
+ *
+ * [mode] is "labeled" (fixed 0..100, read as a percentage) or "numeric"
+ * ([min]/[max] are the field's own, [step] may be null for any value, [unit]
+ * is shown after the number). [gradient] is null or 2 to 8 #RRGGBB colours
+ * painted left to right across the track.
  */
 @JsonClass(generateAdapter = true)
 data class CustomFieldOptions(
     val choices: List<String>? = null,
+    val mode: String? = null,
+    val min: Double? = null,
+    val max: Double? = null,
+    val step: Double? = null,
+    val unit: String? = null,
+    val labels: SliderLabels? = null,
+    val gradient: List<String>? = null,
 )
 
 @JsonClass(generateAdapter = true)
@@ -868,6 +896,7 @@ data class CustomFieldUpdate(
 //   boolean -> Boolean
 //   select  -> String (must be in choices when choices are set)
 //   multiselect -> List<String> (each must be in choices when set)
+//   slider  -> Number, inside [options.min, options.max], never a string
 //
 // Members the viewer isn't permitted to see fields for return an
 // empty list; the per-field privacy gate is enforced server-side.