docs: add Android SDK documentation content

app/globals.css

@@ -2999,103 +2999,46 @@ html.dark .chat-landing {
 }
 
 .chat-hero-visual {
-  min-height: 400px;
-}
-
-.visual-window {
-  position: absolute;
-  top: 34px;
-  right: 0;
-  left: 0;
-  overflow: hidden;
-  border: 1px solid color-mix(in srgb, var(--accent) 22%, var(--border));
-  border-radius: 19px;
-  background: color-mix(in srgb, var(--surface) 96%, transparent);
-  box-shadow: var(--shadow-lg);
-  transform: perspective(1000px) rotateY(-6deg) rotateX(2deg);
-}
-
-.visual-window-bar {
   display: flex;
+  min-height: 430px;
   align-items: center;
-  gap: 6px;
-  height: 39px;
-  padding: 0 14px;
-  border-bottom: 1px solid var(--border);
-  background: var(--surface-soft);
-}
-
-.visual-window-bar i {
-  width: 7px;
-  height: 7px;
-  border-radius: 50%;
-  background: var(--border-strong);
-}
-
-.visual-layout {
-  display: grid;
-  grid-template-columns: 112px 1fr;
-  min-height: 315px;
-}
-
-.visual-sidebar {
-  display: grid;
-  align-content: start;
-  gap: 11px;
-  padding: 24px 16px;
-  border-right: 1px solid var(--border);
-  background: var(--surface-soft);
-}
-
-.visual-sidebar span {
-  height: 8px;
-  border-radius: 4px;
-  background: var(--border-strong);
-}
-
-.visual-sidebar span:nth-child(2) {
-  width: 70%;
-}
-
-.visual-sidebar span:nth-child(3) {
-  width: 84%;
-  background: color-mix(in srgb, var(--accent) 45%, var(--border));
+  justify-content: center;
 }
 
-.visual-thread {
-  display: flex;
-  flex-direction: column;
-  gap: 14px;
-  padding: 34px 31px 25px;
+.chat-hero-product-image {
+  display: block;
+  width: min(100%, 590px);
+  height: auto;
+  border-radius: 26px;
+  box-shadow:
+    0 36px 90px rgb(52 57 125 / 0.18),
+    0 12px 34px rgb(65 53 126 / 0.1);
+  transform: translateY(2px);
+  animation: hero-product-enter 700ms cubic-bezier(0.22, 1, 0.36, 1) both;
 }
 
-.visual-message {
-  width: 78%;
-  height: 52px;
-  border: 1px solid var(--border);
-  border-radius: 5px 15px 15px 15px;
-  background: var(--surface-soft);
+html.dark .chat-hero-product-image {
+  box-shadow:
+    0 38px 100px rgb(0 0 0 / 0.36),
+    0 12px 36px rgb(31 27 74 / 0.28);
 }
 
-.visual-message.is-accent {
-  align-self: flex-end;
-  width: 65%;
-  border-color: color-mix(in srgb, var(--accent) 45%, var(--border));
-  border-radius: 15px 5px 15px 15px;
-  background: var(--accent-soft);
-}
+@keyframes hero-product-enter {
+  from {
+    opacity: 0;
+    transform: translateY(20px) scale(0.985);
+  }
 
-.visual-message.is-short {
-  width: 48%;
-  height: 43px;
+  to {
+    opacity: 1;
+    transform: translateY(2px) scale(1);
+  }
 }
 
-.visual-composer {
-  height: 43px;
-  margin-top: auto;
-  border: 1px solid var(--border);
-  border-radius: 10px;
-  background: var(--surface);
+@media (prefers-reduced-motion: reduce) {
+  .chat-hero-product-image {
+    animation: none;
+  }
 }
 
 .landing-section {
@@ -4329,7 +4272,7 @@ html.dark .guide-markdown a {
   }
 
   .chat-hero-visual {
-    min-height: 350px;
+    min-height: 405px;
   }
 
   .docs-home-section {
@@ -4494,16 +4437,11 @@ html.dark .guide-markdown a {
   }
 
   .chat-hero-visual {
-    min-height: 280px;
-  }
-
-  .visual-layout {
-    grid-template-columns: 75px 1fr;
-    min-height: 245px;
+    min-height: 350px;
   }
 
-  .visual-thread {
-    padding: 22px 17px 17px;
+  .chat-hero-product-image {
+    width: min(100%, 560px);
   }
 
   .docs-home-section {
@@ -4553,10 +4491,6 @@ html.dark .guide-markdown a {
     text-align: left;
   }
 
-  .visual-window {
-    top: 10px;
-  }
-
   .landing-section {
     width: min(100% - 36px, 1180px);
     padding-top: 62px;
@@ -4571,6 +4505,10 @@ html.dark .guide-markdown a {
   .primary-nav {
     display: none;
   }
+
+  .chat-hero-visual {
+    min-height: 300px;
+  }
 }
 
 @media (prefers-reduced-motion: reduce) {

content/docs/chat/sdk/android/calling/managing-calls/accept-call.mdx

@@ -0,0 +1,39 @@
+---
+title: 'Accept a call'
+description: 'Accept a call invitation with the Android SDK and retrieve room credentials.'
+product: 'sdk'
+context: 'chat/sdk/android'
+template: 'guide'
+status: 'published'
+lastUpdated: '2026-08-10'
+version: 'v4'
+platform: 'android'
+sourcePath: '/sdk/android/calling/managing-calls/accept-call'
+---
+
+After receiving the original `SignalingInfo` from `onReceiveNewInvitation`, pass it to `signalingAccept()`:
+
+```java
+OpenIMClient.getInstance().signalingManager.signalingAccept(
+    new OnBase<SignalingCertificate>() {
+        @Override
+        public void onSuccess(SignalingCertificate credentials) {
+            joinMediaRoom(
+                credentials.getRoomID(),
+                credentials.getToken(),
+                credentials.getLiveURL()
+            );
+        }
+
+        @Override
+        public void onError(int code, String error) {
+            showAcceptError(code, error);
+        }
+    },
+    receivedInfo
+);
+```
+
+Preserve the original `roomID`, inviter, invitees, and session type in `receivedInfo`. Do not rebuild it as an object that contains only `roomID`.
+
+The success callback returns `SignalingCertificate`. Connect the media room only after receiving a valid `token` and `roomID`, then keep merging remote state through [Handle call events](/sdk/android/calling/managing-calls/handle-call-events).

content/docs/chat/sdk/android/calling/managing-calls/cancel-call.mdx

@@ -0,0 +1,33 @@
+---
+title: 'Cancel a call invitation'
+description: 'Cancel a call invitation before it is accepted with the Android SDK.'
+product: 'sdk'
+context: 'chat/sdk/android'
+template: 'guide'
+status: 'published'
+lastUpdated: '2026-08-10'
+version: 'v4'
+platform: 'android'
+sourcePath: '/sdk/android/calling/managing-calls/cancel-call'
+---
+
+Before an invitation is accepted, the inviter can call `signalingCancel()`:
+
+```java
+OpenIMClient.getInstance().signalingManager.signalingCancel(
+    new OnBase<String>() {
+        @Override
+        public void onSuccess(String result) {
+            stopWaitingForAnswer(activeInfo.getInvitation().getRoomID());
+        }
+
+        @Override
+        public void onError(int code, String error) {
+            showCancelError(code, error);
+        }
+    },
+    activeInfo
+);
+```
+
+Pass the complete `SignalingInfo` saved when the call was started, not a new object containing only `roomID`. A successful callback means that the cancel request completed. End the local waiting state and release unused media resources; remote clients update through `onInvitationCancelled`.

content/docs/chat/sdk/android/calling/managing-calls/handle-call-events.mdx

@@ -0,0 +1,81 @@
+---
+title: 'Handle call events'
+description: 'Register Android SDK invitation, participant, and media-stream callbacks in one call listener.'
+product: 'sdk'
+context: 'chat/sdk/android'
+template: 'guide'
+status: 'published'
+lastUpdated: '2026-08-10'
+version: 'v4'
+platform: 'android'
+sourcePath: '/sdk/android/calling/managing-calls/handle-call-events'
+---
+
+Register `OnSignalingListener` once in the call state layer. Merge invitation lifecycle, participant connection, and media stream changes by `roomID`.
+
+```java
+OpenIMClient.getInstance().signalingManager.setSignalingListener(
+    new OnSignalingListener() {
+        @Override
+        public void onReceiveNewInvitation(SignalingInfo info) {
+            upsertCall(info, "ringing");
+        }
+
+        @Override
+        public void onInviteeAccepted(SignalingInfo info) {
+            mergeCallEvent("accepted", info);
+        }
+
+        @Override
+        public void onInviteeRejected(SignalingInfo info) {
+            mergeCallEvent("rejected", info);
+        }
+
+        @Override
+        public void onInvitationCancelled(SignalingInfo info) {
+            mergeCallEvent("cancelled", info);
+        }
+
+        @Override
+        public void onInvitationTimeout(SignalingInfo info) {
+            mergeCallEvent("timeout", info);
+        }
+
+        @Override
+        public void onInviteeAcceptedByOtherDevice(SignalingInfo info) {
+            mergeCallEvent("accepted-by-other-device", info);
+        }
+
+        @Override
+        public void onInviteeRejectedByOtherDevice(SignalingInfo info) {
+            mergeCallEvent("rejected-by-other-device", info);
+        }
+
+        @Override
+        public void onHangup(SignalingInfo info) {
+            finishCall(info.getInvitation().getRoomID());
+        }
+
+        @Override
+        public void onRoomParticipantConnected(RoomCallingInfo room) {
+            mergeConnectedParticipants(room.getRoomID(), room.getParticipant());
+        }
+
+        @Override
+        public void onRoomParticipantDisconnected(RoomCallingInfo room) {
+            mergeDisconnectedParticipants(room.getRoomID(), room.getParticipant());
+        }
+
+        @Override
+        public void onStreamChange(String streamInfo) {
+            mergeStreamChange(streamInfo);
+        }
+    }
+);
+```
+
+This page owns the complete handling contract for the 11 call callbacks exposed by the Android adapter other than `onReceiveCustomSignal`. Custom signaling belongs to [Send a custom signal](/sdk/android/calling/sending-custom-signals/send-a-custom-signal).
+
+Merge invitation events with `SignalingInfo.invitation.roomID`. Merge participant state with `RoomCallingInfo.roomID` plus the participant user ID. Do not merge by event order, display name, or array position. `onStreamChange` currently carries a string payload; parse and validate it according to the actual server protocol used by your deployment.
+
+`SignalingManager` retains one listener. Setting another replaces the previous instance, and there is no public remove method. Combine custom signaling with these callbacks in the same application-level listener. When signing out or switching accounts, stop writing into old account state and replace the listener with the complete listener for the new account.

content/docs/chat/sdk/android/calling/managing-calls/hang-up-call.mdx

@@ -0,0 +1,33 @@
+---
+title: 'Hang up a call'
+description: 'Hang up an established call with the Android SDK.'
+product: 'sdk'
+context: 'chat/sdk/android'
+template: 'guide'
+status: 'published'
+lastUpdated: '2026-08-10'
+version: 'v4'
+platform: 'android'
+sourcePath: '/sdk/android/calling/managing-calls/hang-up-call'
+---
+
+After a call is established, a participant can call `signalingHungUp()`. The supplied `SignalingInfo` should preserve the complete invitation, and its `roomID` must match the active media room.
+
+```java
+OpenIMClient.getInstance().signalingManager.signalingHungUp(
+    new OnBase<String>() {
+        @Override
+        public void onSuccess(String result) {
+            releaseCallResources(activeInfo.getInvitation().getRoomID());
+        }
+
+        @Override
+        public void onError(int code, String error) {
+            showHangUpError(code, error);
+        }
+    },
+    activeInfo
+);
+```
+
+The success callback only means that the hang-up request completed. Stop local capture, disconnect the media room, and release the camera and microphone. Cancellation, rejection, timeout, and hang-up should all enter one idempotent cleanup flow keyed by `roomID`.