docs: add plan justifying removing left padding on consecutive received messages in channels

plans/2026-06-20-channel-received-no-avatar-left-padding.md

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+# Remove left padding on consecutive (no-avatar) received messages in channels
+
+## Problem
+
+In a channel, received messages show the sender avatar on the first message of a
+run and hide it on consecutive messages, but those consecutive messages still
+reserve the avatar-sized **left padding** so they line up under the first. For a
+channel's feed-style layout this indentation wastes horizontal space —
+consecutive received messages should sit flush-left where the avatar would be.
+This applies to **both** the channel owner's broadcasts and contributors' posts.
+
+Desired behaviour: in channels, any received message that does **not** show an
+avatar (a consecutive post from the same sender) drops the avatar-sized left
+padding. The first message of a run still shows the avatar and keeps its layout;
+when the run is broken (a different sender, or a time gap), the next message
+shows the avatar again — this run logic is unchanged, only the no-avatar left
+padding is reduced.
+
+## The two received directions in a channel
+
+Received items in a channel arrive as one of two directions
+(`Subscriber.hs`, `saveRcvCI`):
+
+- **`ChannelRcv`** (no member) — the **owner's** broadcast, sent "as the channel".
+  The backend permits sending-as-group only to the owner, and a channel owner's
+  main-scope messages are always sent as group (`ChatInfo.sendAsGroup` is true
+  for `useRelays && memberRole >= Owner` in the main scope), so received owner
+  posts arrive as `ChannelRcv`. Shows the channel avatar.
+- **`GroupRcv(member)`** (attributed) — a **contributor's** post, carrying the
+  member. Shows the member avatar.
+
+Both are received messages, and the change now applies to **both** when they hide
+the avatar. (An earlier revision scoped this to `ChannelRcv`/owner only; it now
+covers contributors too, per request.)
+
+## Change
+
+In channels — gated on `ChatInfo.isChannel` (the `useRelays` flag, which is
+reliably present, unlike the optional group-type predicate) — the no-avatar
+branches for **both** `ChannelRcv` and `GroupRcv` drop the avatar-sized left
+padding down to the base inset where the avatar itself starts. In non-channel
+groups the `GroupRcv` no-avatar layout is unchanged (`isChannel` is false). The
+avatar-shown layouts, sent messages, and all other chats are unchanged.
+
+The same Row's `end` padding is already gated on `chatInfo.isChannel` (the merged
+right-gap change #7106), so gating `start` on `isChannel` keeps each Row
+internally consistent and the change precisely "in channels".
+
+### Android / desktop (`apps/multiplatform`, `ChatView.kt`, `ChatItemsList`)
+
+Both the `CIDirection.GroupRcv` and `CIDirection.ChannelRcv` `showAvatar == false`
+rows:
+
+```kotlin
+// before
+.padding(start = 8.dp + (MEMBER_IMAGE_SIZE * fontSizeSqrtMultiplier) + 4.dp, end = …)
+// after
+.padding(start = if (chatInfo.isChannel) 8.dp else 8.dp + (MEMBER_IMAGE_SIZE * fontSizeSqrtMultiplier) + 4.dp, end = …)
+```
+
+### iOS (`apps/ios`, `ChatView.swift`, `chatItemListView`)
+
+Both the `.groupRcv` and `.channelRcv` no-avatar branches:
+
+```swift
+// before
+.padding(.leading, 10 + memberImageSize + 12)
+// after
+.padding(.leading, chat.chatInfo.isChannel ? 12 : 10 + memberImageSize + 12)
+```
+
+## Run behaviour (unchanged)
+
+`shouldShowAvatar(current, older)` shows the avatar on the first message of a
+same-sender run and hides it on consecutive ones; a different sender or a gap
+resets the run. For `GroupRcv` "same sender" is the same `memberId`; for
+`ChannelRcv` consecutive channel broadcasts count as the same sender. Only the
+no-avatar left padding is changed.
+
+## Scope
+
+- Affects: all received consecutive (no-avatar) messages **in channels** — owner
+  broadcasts (`ChannelRcv`) and contributor posts (`GroupRcv`). This includes a
+  channel's member-support sub-scope, which renders through the same
+  `ChatItemsList` with the channel's `isChannel`; treating it the same way is
+  consistent with the merged right-gap change (#7106), which also gates that
+  Row's `end` padding on `isChannel` without a scope filter.
+- Unchanged: the first message of each run (avatar shown), sent messages, regular
+  groups, business chats and direct chats (`isChannel` false — the `else` branch
+  preserves the original avatar-inset value exactly), and any non-channel
+  `ChannelRcv` welcome item.
+
+## Verification
+
+- Android/desktop: `:common:compileKotlinDesktop` compiles clean.
+- iOS: small, type-safe constant change; build/verify on macOS (Xcode) — not
+  compilable on the Linux build host used here.
+- Visual (both platforms), in a channel:
+  - First message of a run (owner or contributor): avatar shown, layout unchanged.
+  - Following messages from the same sender (no avatar): now flush-left.
+  - A different sender / time gap resets the run — the next message shows the
+    avatar again.
+  - Regular groups, business and direct chats keep their existing indentation.