K2GO-385 refactor(ui): shared filter chip + boot-surface download buttons (PR3c)

controller/app/src/main/java/org/appdevforall/k2go/kolibri/presentation/KolibriBrowseFragment.java

@@ -37,6 +37,7 @@
 import org.appdevforall.k2go.R;
 import org.appdevforall.k2go.applang.data.ContentLanguage;
 import org.appdevforall.k2go.kolibri.domain.Channel;
+import org.appdevforall.k2go.redesign.K2GoFilterChip;
 import org.appdevforall.k2go.redesign.SetupLibraryActivity;
 import org.appdevforall.k2go.redesign.ZimLanguageDialog;
 import org.appdevforall.k2go.util.ByteFormatter;
@@ -80,8 +81,8 @@ public final class KolibriBrowseFragment extends Fragment {
     private TextView storageLabel;
     private ProgressBar storageBar;
     private LinearLayout chips;
-    private TextView sortSize;
-    private TextView sortName;
+    private com.google.android.material.chip.Chip sortSize;
+    private com.google.android.material.chip.Chip sortName;
     private LinearLayout list;
     private Button review;
 
@@ -281,11 +282,10 @@ private void updateSortControls() {
         pill(sortName, s.isName());
     }
 
-    /** The one pill style in the app: teal filled when on, hairline outline when off. */
-    private void pill(TextView t, boolean on) {
-        t.setBackgroundResource(on ? R.drawable.k2go_chip_bg : R.drawable.k2go_pill_bg);
-        t.setTextColor(ContextCompat.getColor(requireContext(),
-                on ? android.R.color.white : R.color.k2go_ink));
+    // K2GO-385 (PR3): the shared filter chip (8dp, 32dp, check when active) -- the sort toggles now match
+    // the ZIM sort chips and the category/Books filters; the label still carries the sort direction.
+    private void pill(com.google.android.material.chip.Chip t, boolean on) {
+        K2GoFilterChip.style(t, on);
     }
 
     /**
@@ -456,25 +456,19 @@ private void buildChips(KolibriCatalogUiState s) {
     }
 
     private View chip(String label, final String group) {
-        TextView t = new TextView(requireContext());
-        t.setText(label);
-        t.setTextAppearance(com.google.android.material.R.style.TextAppearance_Material3_BodySmall);
-        t.setGravity(Gravity.CENTER);
-        t.setMinHeight(px(48));   // tap target, even though the pill looks smaller
-        t.setPadding(px(14), px(8), px(14), px(8));
-        pill(t, group.equals(groupFilter));
-
+        // K2GO-385 (PR3): category chips use the shared filter chip too.
+        com.google.android.material.chip.Chip c = K2GoFilterChip.create(requireContext(), label,
+                group.equals(groupFilter), x -> {
+                    if (!group.equals(groupFilter)) {
+                        groupFilter = group;
+                        render(vm.state().getValue());
+                    }
+                });
         LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
                 LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
         lp.rightMargin = px(8);
-        t.setLayoutParams(lp);
-        t.setOnClickListener(x -> {
-            if (!group.equals(groupFilter)) {
-                groupFilter = group;
-                render(vm.state().getValue());
-            }
-        });
-        return t;
+        c.setLayoutParams(lp);
+        return c;
     }
 
     private void updateStorage() {

controller/app/src/main/java/org/appdevforall/k2go/redesign/BooksLandingFragment.java

@@ -37,6 +37,8 @@
 import androidx.fragment.app.Fragment;
 
 import org.appdevforall.k2go.PortalActivity;
+import com.google.android.material.chip.Chip;
+
 import org.appdevforall.k2go.R;
 import org.appdevforall.k2go.config.BoxEndpoints;
 import org.json.JSONArray;
@@ -200,22 +202,10 @@ private void openLanguagePicker() {
                 () -> { lang = ""; updateLangPill(); loadBooks(); });
     }
 
-    private TextView chip(String text, boolean on, Runnable onClick) {
-        TextView t = new TextView(requireContext());
-        t.setText(text);
-        t.setPadding(px(14), px(8), px(14), px(8));
-        t.setBackgroundResource(on ? R.drawable.k2go_chip_bg : R.drawable.k2go_pill_bg);
-        // ADFA-5248: apply the text appearance FIRST, then the color. TextAppearance_Material3_*
-        // carries its own colorOnSurface, so setting the color before it silently overwrote the chip
-        // color (the real bug the ticket reported: onSurface flips with the theme, giving dark-on-
-        // dark-teal in light mode and light-on-aqua in dark mode — never legible on the teal fill).
-        // With the order fixed, k2go_on_teal sticks: it flips against the fill (light text on the
-        // dark-teal light-mode fill, dark text on the light-aqua dark-mode fill).
-        t.setTextAppearance(com.google.android.material.R.style.TextAppearance_Material3_BodySmall);
-        t.setTextColor(ContextCompat.getColor(requireContext(), on ? R.color.k2go_on_teal : R.color.k2go_ink));
-        t.setClickable(true);
-        t.setOnClickListener(v -> onClick.run());
-        return t;
+    // K2GO-385 (PR3): the shared filter chip (8dp corner, 32dp, check when selected). Replaces the
+    // per-screen k2go_chip_bg/k2go_pill_bg drawable pair that had drifted from the other filter surfaces.
+    private Chip chip(String text, boolean on, Runnable onClick) {
+        return K2GoFilterChip.create(requireContext(), text, on, v -> onClick.run());
     }
 
     private void loadLibrary() {

controller/app/src/main/java/org/appdevforall/k2go/redesign/FqrController.java

@@ -443,13 +443,15 @@ private void showOverlay(String name, long sizeBytes) {
         // ADFA-4896: Stop/Retry beside Cancel. The label follows the reported state; the tap fires the
         // matching verb and the poll (onPaused/onProgress) is the source of truth.
         overlayStopped = false;
-        overlayStop = new MaterialButton(themed, null,
-                com.google.android.material.R.attr.materialButtonOutlinedStyle);
+        // K2GO-385 (PR3): the download controls use the app button system (K2Go outlined stadium) via the
+        // shared overlay, not a bare Material3 outlined button. FQR's overlay is a themed (day/night)
+        // surface, so the K2Go outlined style's theme teal is right here -- not the fixed boot tokens.
+        ContextThemeWrapper btnCtx = new ContextThemeWrapper(themed, R.style.ThemeOverlay_K2Go_Button_Outlined);
+        overlayStop = new MaterialButton(btnCtx, null);
         overlayStop.setText(R.string.k2go_clone_stop_confirm);
         overlayStop.setOnClickListener(v -> toggleStop());
         row.addView(overlayStop);
-        MaterialButton cancel = new MaterialButton(themed, null,
-                com.google.android.material.R.attr.materialButtonOutlinedStyle);
+        MaterialButton cancel = new MaterialButton(btnCtx, null);
         cancel.setText(R.string.k2go_cancel);
         cancel.setOnClickListener(v -> { client.cancel(); hideOverlay(); });
         row.addView(cancel);

controller/app/src/main/java/org/appdevforall/k2go/redesign/K2GoFilterChip.java

@@ -0,0 +1,75 @@
+/*
+ * ============================================================================
+ * Name        : K2GoFilterChip.java
+ * Author      : AppDevForAll
+ * Copyright   : Copyright (c) 2026 AppDevForAll
+ * Description : K2GO-385 (PR3). The shared FILTER CHIP (pill-roles design decision, board
+ *               k2go-chip-vs-button-v1): a selectable/toggle chip -- Popular / Educational, a ZIM
+ *               category, a sort order. Per the decision it is an 8dp-corner, ~32dp Material 3 chip
+ *               with a leading check when selected -- "8dp corner + check = toggle", distinct on
+ *               purpose from the stadium action button, the dot+text status and the 8dp metadata
+ *               tag. Built ONCE here instead of the three drifted per-screen chip builders it
+ *               replaces (ZimLanding / ZimCategory / BooksLanding). Colour is the app teal (filled +
+ *               on-teal text when selected; transparent + teal outline + teal text when not). Pure
+ *               UI; no domain/data dependencies.
+ * ============================================================================
+ */
+package org.appdevforall.k2go.redesign;
+
+import android.content.Context;
+import android.content.res.ColorStateList;
+import android.graphics.Color;
+import android.view.View;
+
+import androidx.core.content.ContextCompat;
+
+import com.google.android.material.chip.Chip;
+
+import org.appdevforall.k2go.R;
+
+public final class K2GoFilterChip {
+
+    private K2GoFilterChip() {}
+
+    /**
+     * Build a selectable filter chip. {@code selected} sets the checked look (teal fill + check);
+     * {@code onClick} fires on tap -- the caller owns the selection model (usually rebuilding the
+     * row), so the chip is a view of that state, not the source of truth.
+     */
+    public static Chip create(Context ctx, CharSequence label, boolean selected, View.OnClickListener onClick) {
+        Chip chip = new Chip(ctx);
+        chip.setText(label);
+        style(chip, selected);
+        chip.setOnClickListener(onClick);
+        return chip;
+    }
+
+    /**
+     * Apply the filter-chip look + selected state to an EXISTING chip (e.g. one inflated from XML,
+     * like the ZimCategory sort chips). Idempotent -- safe to call on every render. The caller owns
+     * the text (so a sort chip can carry its "By size ▲" direction) and the click.
+     */
+    public static void style(Chip chip, boolean selected) {
+        Context ctx = chip.getContext();
+        float d = ctx.getResources().getDisplayMetrics().density;
+        chip.setCheckable(true);
+        chip.setChecked(selected);
+        chip.setCheckedIconVisible(true);            // the "check" cue the design calls for
+        // A bare new Chip(ctx) picks up the theme's default (Assist) chipStyle, which has NO checkedIcon,
+        // so set a plain check explicitly -- otherwise setCheckedIconVisible shows nothing.
+        chip.setCheckedIcon(ContextCompat.getDrawable(ctx, R.drawable.ic_check_16));
+        chip.setChipCornerRadius(8 * d);             // 8dp corner = chip/toggle (not a stadium pill)
+        chip.setChipMinHeight(32 * d);               // the 32dp step on the 4dp role ladder
+        chip.setEnsureMinTouchTargetSize(true);      // keep a >=48dp touch target on the 32dp chip
+        chip.setTextAppearance(com.google.android.material.R.style.TextAppearance_Material3_LabelLarge);
+
+        int teal = ContextCompat.getColor(ctx, R.color.k2go_teal);
+        int onTeal = ContextCompat.getColor(ctx, R.color.k2go_on_teal);
+        int[][] states = { new int[]{ android.R.attr.state_checked }, new int[0] };
+        chip.setChipBackgroundColor(new ColorStateList(states, new int[]{ teal, Color.TRANSPARENT }));
+        chip.setChipStrokeColor(new ColorStateList(states, new int[]{ Color.TRANSPARENT, teal }));
+        chip.setChipStrokeWidth(Math.max(1, Math.round(1.4f * d)));
+        chip.setTextColor(new ColorStateList(states, new int[]{ onTeal, teal }));
+        chip.setCheckedIconTint(ColorStateList.valueOf(onTeal));
+    }
+}

controller/app/src/main/java/org/appdevforall/k2go/redesign/ZimCategoryFragment.java

@@ -71,7 +71,8 @@ private static final class Entry {
     private long freeMb = 0, totalMb = 0;
 
     private LinearLayout list;
-    private TextView freeLabel, sortSize, sortName, sortGroup, count, langCurrent, langSub;
+    private TextView freeLabel, count, langCurrent, langSub;
+    private com.google.android.material.chip.Chip sortSize, sortName, sortGroup;
     private ProgressBar bar;
     private Button add;
 
@@ -275,10 +276,11 @@ private void addHeader(String title, String desc) {
         list.addView(h);
     }
 
-    private void chip(TextView t, boolean on) {
-        t.setBackgroundResource(on ? R.drawable.k2go_chip_bg : R.drawable.k2go_pill_bg);
-        // ADFA-4910: white on the selected (teal) chip (same fix as Books / MapsChoose).
-        t.setTextColor(ContextCompat.getColor(requireContext(), on ? android.R.color.white : R.color.k2go_ink));
+    // K2GO-385 (PR3): the sort chips use the one shared filter chip (8dp, 32dp, check when active) so
+    // they stop looking different from the category/Books filter chips; the label still carries the
+    // sort direction (e.g. "By size ▲").
+    private void chip(com.google.android.material.chip.Chip t, boolean on) {
+        K2GoFilterChip.style(t, on);
     }
 
     // ADFA-5033: flat list row (spec §10) — a simple line with a hairline between rows, NOT a card.

controller/app/src/main/java/org/appdevforall/k2go/redesign/ZimLandingFragment.java

@@ -28,6 +28,8 @@
 import androidx.core.content.ContextCompat;
 import androidx.fragment.app.Fragment;
 
+import com.google.android.material.chip.Chip;
+
 import org.appdevforall.k2go.R;
 import org.appdevforall.k2go.applang.data.ContentLanguage;
 import org.json.JSONObject;
@@ -253,36 +255,19 @@ private void buildChips() {
 
     private View chip(String label, String groupKey) {
         boolean selected = (groupKey == null) ? (selectedGroup == null) : groupKey.equals(selectedGroup);
-        int teal = ContextCompat.getColor(requireContext(), R.color.k2go_teal);
-        TextView t = new TextView(requireContext());
-        t.setText(label);
-        t.setTextAppearance(com.google.android.material.R.style.TextAppearance_Material3_LabelLarge);
-        t.setGravity(Gravity.CENTER);
-        t.setMinHeight(px(48));   // ADFA-5033: ≥48dp tap target (spec §9)
-        t.setPadding(px(14), px(6), px(14), px(6));
-        android.graphics.drawable.GradientDrawable bg = new android.graphics.drawable.GradientDrawable();
-        bg.setShape(android.graphics.drawable.GradientDrawable.RECTANGLE);
-        bg.setCornerRadius(px(24));   // full pill at 48dp
-        if (selected) {
-            bg.setColor(teal);
-            t.setTextColor(android.graphics.Color.WHITE);
-        } else {
-            bg.setColor(android.graphics.Color.TRANSPARENT);
-            bg.setStroke(Math.max(1, Math.round(1.4f * getResources().getDisplayMetrics().density)), teal);
-            t.setTextColor(teal);
-        }
-        t.setBackground(bg);
-        LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
-                LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
-        lp.rightMargin = px(8);
-        t.setLayoutParams(lp);
-        t.setOnClickListener(v -> {
+        // K2GO-385 (PR3): one shared filter chip (8dp corner, 32dp, check when selected) -- replaces the
+        // per-screen 48dp teal pill that had drifted from the other filter surfaces.
+        Chip c = K2GoFilterChip.create(requireContext(), label, selected, v -> {
             selectedGroup = groupKey;
             expanded = false;
             buildChips();
             buildRows();
         });
-        return t;
+        LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
+                LinearLayout.LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
+        lp.rightMargin = px(8);
+        c.setLayoutParams(lp);
+        return c;
     }
 
     /** Teal caps section header (MOST CONTENT / group headers). */

controller/app/src/main/res/drawable/ic_check_16.xml

@@ -0,0 +1,10 @@
+<!-- K2GO-385 (PR3): plain checkmark for the filter chip's checked state. Tinted by the chip. -->
+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="18dp"
+    android:height="18dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24">
+    <path
+        android:fillColor="#FFFFFFFF"
+        android:pathData="M9,16.17L4.83,12l-1.42,1.41L9,19 21,7l-1.41,-1.41z" />
+</vector>

controller/app/src/main/res/layout/activity_library.xml

@@ -201,22 +201,17 @@
             android:visibility="gone">
             <com.google.android.material.button.MaterialButton
                 android:id="@+id/k2go_dl_toggle"
-                style="@style/Widget.Material3.Button.OutlinedButton"
+                style="@style/Widget.K2Go.Button.Outlined.OnBootPaper"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                android:minWidth="132dp"
-                android:textColor="@color/k2go_boot_ink"
-                app:strokeColor="@color/k2go_boot_ink"
-                app:rippleColor="@color/k2go_boot_muted" />
+                android:minWidth="132dp" />
             <com.google.android.material.button.MaterialButton
                 android:id="@+id/k2go_dl_cancel"
-                style="@style/Widget.Material3.Button.TextButton"
+                style="@style/Widget.K2Go.Button.Text.OnBootPaper"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
                 android:layout_marginStart="8dp"
-                android:text="@string/k2go_dl_cancel"
-                android:textColor="@color/k2go_boot_muted"
-                app:rippleColor="@color/k2go_boot_muted" />
+                android:text="@string/k2go_dl_cancel" />
         </LinearLayout>
     </LinearLayout>
 </FrameLayout>

controller/app/src/main/res/layout/fragment_k2go_kolibri_browse.xml

@@ -133,26 +133,16 @@
             android:layout_marginTop="12dp"
             android:orientation="horizontal">
 
-            <TextView
+            <com.google.android.material.chip.Chip
                 android:id="@+id/k2go_kbrowse_sort_size"
                 android:layout_width="wrap_content"
-                android:layout_height="wrap_content"
-                android:paddingLeft="12dp"
-                android:paddingRight="12dp"
-                android:paddingTop="8dp"
-                android:paddingBottom="8dp"
-                android:textAppearance="?attr/textAppearanceBodySmall" />
+                android:layout_height="wrap_content" />
 
-            <TextView
+            <com.google.android.material.chip.Chip
                 android:id="@+id/k2go_kbrowse_sort_name"
                 android:layout_width="wrap_content"
                 android:layout_height="wrap_content"
-                android:layout_marginStart="8dp"
-                android:paddingLeft="12dp"
-                android:paddingRight="12dp"
-                android:paddingTop="8dp"
-                android:paddingBottom="8dp"
-                android:textAppearance="?attr/textAppearanceBodySmall" />
+                android:layout_marginStart="8dp" />
         </LinearLayout>
 
         <!-- Count on its own line so it can never share the scrollable chip row. -->

controller/app/src/main/res/layout/fragment_k2go_zim_category.xml

@@ -100,23 +100,17 @@
             android:layout_marginTop="12dp"
             android:orientation="horizontal">
 
-            <TextView android:id="@+id/k2go_zc_sort_size"
-                android:layout_width="wrap_content" android:layout_height="wrap_content"
-                android:paddingLeft="12dp" android:paddingRight="12dp" android:paddingTop="8dp" android:paddingBottom="8dp"
-                android:textAppearance="?attr/textAppearanceBodySmall" />
+            <com.google.android.material.chip.Chip android:id="@+id/k2go_zc_sort_size"
+                android:layout_width="wrap_content" android:layout_height="wrap_content" />
 
-            <TextView android:id="@+id/k2go_zc_sort_name"
+            <com.google.android.material.chip.Chip android:id="@+id/k2go_zc_sort_name"
                 android:layout_width="wrap_content" android:layout_height="wrap_content"
-                android:layout_marginStart="8dp"
-                android:paddingLeft="12dp" android:paddingRight="12dp" android:paddingTop="8dp" android:paddingBottom="8dp"
-                android:textAppearance="?attr/textAppearanceBodySmall" />
+                android:layout_marginStart="8dp" />
 
-            <TextView android:id="@+id/k2go_zc_sort_group"
+            <com.google.android.material.chip.Chip android:id="@+id/k2go_zc_sort_group"
                 android:layout_width="wrap_content" android:layout_height="wrap_content"
                 android:layout_marginStart="8dp"
-                android:paddingLeft="12dp" android:paddingRight="12dp" android:paddingTop="8dp" android:paddingBottom="8dp"
-                android:text="@string/k2go_zc_sort_group"
-                android:textAppearance="?attr/textAppearanceBodySmall" />
+                android:text="@string/k2go_zc_sort_group" />
         </LinearLayout>
 
         <!-- ADFA-5033: count on its OWN line (design board k2go-count-overflow-v1) so it never shares the