diff --git a/desktop/src/features/channels/lib/threadFocusLayout.ts b/desktop/src/features/channels/lib/threadFocusLayout.ts
index f14f3399b..f0b40348d 100644
--- a/desktop/src/features/channels/lib/threadFocusLayout.ts
+++ b/desktop/src/features/channels/lib/threadFocusLayout.ts
@@ -24,7 +24,7 @@ export const THREAD_FOCUS_SLIVER_WIDTH_PX = 72;
  * with auto horizontal margins so the reading measure stays comfortable no
  * matter how wide the window gets.
  */
-export const THREAD_FOCUS_COLUMN_MAX_WIDTH_PX = 880;
+export const THREAD_FOCUS_COLUMN_MAX_WIDTH_PX = 820;
 
 /**
  * Horizontal distance the focus drawer travels on enter/exit.
diff --git a/desktop/src/features/home/ui/InboxListPane.tsx b/desktop/src/features/home/ui/InboxListPane.tsx
index 17b06bf28..446cd3a65 100644
--- a/desktop/src/features/home/ui/InboxListPane.tsx
+++ b/desktop/src/features/home/ui/InboxListPane.tsx
@@ -13,6 +13,7 @@ import {
   DraftsPanel,
   type DraftViewItem,
 } from "@/features/messages/ui/DraftsPanel";
+import { MessageAuthorText } from "@/features/messages/ui/MessageHeader";
 import { UserProfilePopover } from "@/features/profile/ui/UserProfilePopover";
 import type { Reminder } from "@/features/reminders/lib/reminderTypes";
 import { isDue } from "@/features/reminders/lib/reminderFilters";
@@ -351,7 +352,7 @@ export function InboxListPane({
             <div className="min-w-0 flex-1">
               <div className="flex min-w-0 items-start gap-2">
                 <span
-                  className="flex min-w-0 flex-1 items-start leading-4"
+                  className="flex min-w-0 flex-1 items-start leading-message-author"
                   data-inbox-profile-trigger="true"
                 >
                   <UserProfilePopover
@@ -360,14 +361,14 @@ export function InboxListPane({
                     role={profileRole}
                     triggerElement="span"
                   >
-                    <span className="block max-w-full truncate rounded text-sm font-semibold leading-4 text-foreground focus-visible:outline-hidden focus-visible:ring-2 focus-visible:ring-ring">
+                    <MessageAuthorText className="block max-w-full">
                       {item.senderLabel}
-                    </span>
+                    </MessageAuthorText>
                   </UserProfilePopover>
                 </span>
                 <span
                   className={cn(
-                    "flex shrink-0 items-center gap-1.5 text-xs leading-4 text-muted-foreground/70 transition-opacity group-hover/inbox-item:opacity-0 group-focus-within/inbox-item:opacity-0",
+                    "flex shrink-0 items-center gap-1.5 text-message-timestamp text-muted-foreground/70 transition-opacity group-hover/inbox-item:opacity-0 group-focus-within/inbox-item:opacity-0",
                     isDone ? "font-normal" : "font-medium",
                   )}
                 >
@@ -402,14 +403,14 @@ export function InboxListPane({
 
               <div
                 className={cn(
-                  "mt-1.5 text-sm leading-5 [&_a]:font-medium [&_a]:text-current",
+                  "mt-1.5 text-message [&_a]:font-medium [&_a]:text-current",
                   isDone
                     ? "font-normal text-muted-foreground"
                     : "font-semibold text-foreground",
                 )}
               >
                 <Markdown
-                  className="inbox-preview-markdown text-inherit leading-5"
+                  className="inbox-preview-markdown text-inherit"
                   content={item.preview}
                   interactive={false}
                   mentionNames={item.mentionNames}
diff --git a/desktop/src/features/home/ui/InboxMessageRow.tsx b/desktop/src/features/home/ui/InboxMessageRow.tsx
index 039d418a1..7b5d8b4a8 100644
--- a/desktop/src/features/home/ui/InboxMessageRow.tsx
+++ b/desktop/src/features/home/ui/InboxMessageRow.tsx
@@ -8,6 +8,10 @@ import type { TimelineMessage } from "@/features/messages/types";
 import { getConfigNudgeAuthorPubkey } from "@/features/messages/ui/configNudgeAuthPubkey";
 import { MessageActionBar } from "@/features/messages/ui/MessageActionBar";
 import { MessageAgentOwner } from "@/features/messages/ui/MessageAgentOwner";
+import {
+  MessageAuthorText,
+  MessageHeaderRow,
+} from "@/features/messages/ui/MessageHeader";
 import { MessageReactions } from "@/features/messages/ui/MessageReactions";
 import { UnreadDivider } from "@/features/messages/ui/UnreadDivider";
 import { useReactionHandler } from "@/features/messages/ui/useReactionHandler";
@@ -109,7 +113,7 @@ export function InboxMessageRow({
       ) : null}
       <article
         className={cn(
-          "group/message relative z-10 mx-1 flex gap-2.5 rounded-2xl px-2 py-1 transition-colors hover:bg-muted/50 focus-within:bg-muted/50",
+          "group/message relative z-10 mx-1 flex gap-2.5 rounded-2xl px-2 py-conversation-row transition-colors hover:bg-muted/50 focus-within:bg-muted/50",
           isContinuation ? "items-center" : "items-start",
         )}
         data-message-id={message.id}
@@ -151,7 +155,10 @@ export function InboxMessageRow({
             className="flex w-9 shrink-0 self-stretch items-start justify-end pt-0.5"
             title={message.fullTimestampLabel}
           >
-            <p className="shrink-0 cursor-default whitespace-nowrap text-xs font-normal leading-4 tabular-nums text-muted-foreground/55 opacity-0 transition-opacity group-hover/message:opacity-100 group-focus-within/message:opacity-100">
+            <p
+              className="shrink-0 cursor-default whitespace-nowrap text-message-timestamp font-normal tabular-nums text-muted-foreground/55 opacity-0 transition-opacity group-hover/message:opacity-100 group-focus-within/message:opacity-100"
+              data-testid="inbox-message-timestamp"
+            >
               {hoverTimestampLabel}
             </p>
           </div>
@@ -175,18 +182,18 @@ export function InboxMessageRow({
           </div>
         )}
 
-        <div className="min-w-0 flex-1">
+        <div className="flex min-w-0 flex-1 flex-col gap-0.5">
           {isContinuation ? null : (
-            <div className="flex min-w-0 flex-wrap items-center gap-x-2 gap-y-0">
+            <MessageHeaderRow className="gap-x-2">
               <UserProfilePopover
                 botIdenticonValue={message.authorLabel}
                 pubkey={message.authorPubkey}
                 role={profileRole}
                 triggerElement="span"
               >
-                <span className="block max-w-full truncate rounded text-sm font-semibold text-foreground focus-visible:outline-hidden focus-visible:ring-2 focus-visible:ring-ring">
+                <MessageAuthorText className="block max-w-full">
                   {message.authorLabel}
-                </span>
+                </MessageAuthorText>
               </UserProfilePopover>
               {message.isAgent ? (
                 <MessageAgentOwner
@@ -194,16 +201,19 @@ export function InboxMessageRow({
                   ownerPubkey={message.ownerPubkey}
                 />
               ) : null}
-              <p className="shrink-0 text-xs font-normal tabular-nums text-muted-foreground/55">
+              <p
+                className="shrink-0 text-message-timestamp font-normal tabular-nums text-muted-foreground/55"
+                data-testid="inbox-message-timestamp"
+              >
                 {message.fullTimestampLabel}
               </p>
-            </div>
+            </MessageHeaderRow>
           )}
 
-          <div className={isContinuation ? "mt-0" : "mt-0.5"}>
+          <div className={isContinuation ? "mt-0" : "mt-conversation-body"}>
             <Markdown
               className={cn(
-                "max-w-full text-left text-sm text-foreground",
+                "max-w-full text-left text-message text-foreground",
                 emojiOnly &&
                   "text-4xl leading-tight [&_p]:leading-tight [&_img[data-custom-emoji]]:h-[1.45em] [&_img[data-custom-emoji]]:align-middle [&_button:has(img[data-custom-emoji])]:align-middle",
               )}
diff --git a/desktop/src/features/messages/lib/messageThreadPanelLayout.ts b/desktop/src/features/messages/lib/messageThreadPanelLayout.ts
index 9467d5d3b..121e82ef3 100644
--- a/desktop/src/features/messages/lib/messageThreadPanelLayout.ts
+++ b/desktop/src/features/messages/lib/messageThreadPanelLayout.ts
@@ -4,15 +4,15 @@
  */
 
 /** Inline gutter around thread message rows. */
-export const THREAD_PANEL_MESSAGE_GUTTER_CLASS = "px-2";
+export const THREAD_PANEL_MESSAGE_GUTTER_CLASS = "px-4";
 
 /** Inline gutter around the thread composer and its activity row. */
 export const THREAD_PANEL_COMPOSER_GUTTER_CLASS = "px-5";
 
 /**
  * Centers the reading column when a `columnMaxWidthPx` is supplied (focus-mode
- * drawer). `px-10` (40px) is the inline gutter between the column and the drawer
- * edges; the max-width itself is applied inline since it is a caller-provided
- * pixel value.
+ * drawer). The responsive inline gutter keeps compact overlays usable while
+ * retaining the calmer 40px edge at desktop widths; the max-width itself is
+ * applied inline since it is a caller-provided pixel value.
  */
-export const THREAD_PANEL_COLUMN_CLASS = "mx-auto w-full px-10";
+export const THREAD_PANEL_COLUMN_CLASS = "mx-auto w-full px-6 sm:px-10";
diff --git a/desktop/src/features/messages/lib/useRichTextEditor.ts b/desktop/src/features/messages/lib/useRichTextEditor.ts
index e800787ca..5a73a9a96 100644
--- a/desktop/src/features/messages/lib/useRichTextEditor.ts
+++ b/desktop/src/features/messages/lib/useRichTextEditor.ts
@@ -510,7 +510,7 @@ export function useRichTextEditor({
         attributes: {
           autocapitalize: "none",
           autocorrect: "off",
-          class: `${MESSAGE_MARKDOWN_CLASS} min-h-0 resize-none overflow-y-hidden border-0 bg-transparent px-0 py-0 text-sm leading-5 text-foreground shadow-none focus-visible:ring-0 caret-foreground outline-hidden max-w-none`,
+          class: `${MESSAGE_MARKDOWN_CLASS} min-h-0 resize-none overflow-y-hidden border-0 bg-transparent px-0 py-0 text-message font-normal tracking-normal text-foreground shadow-none focus-visible:ring-0 caret-foreground outline-hidden max-w-none`,
           "data-testid": "message-input",
           spellcheck: "true",
         },
diff --git a/desktop/src/features/messages/ui/MessageAgentOwner.tsx b/desktop/src/features/messages/ui/MessageAgentOwner.tsx
index e5b92cd73..c5d77c3f6 100644
--- a/desktop/src/features/messages/ui/MessageAgentOwner.tsx
+++ b/desktop/src/features/messages/ui/MessageAgentOwner.tsx
@@ -1,5 +1,3 @@
-import { Bot } from "lucide-react";
-
 import { UserProfilePopover } from "@/features/profile/ui/UserProfilePopover";
 
 export function MessageAgentOwner({
@@ -11,7 +9,7 @@ export function MessageAgentOwner({
 }) {
   return (
     <span
-      className="inline-flex min-w-0 max-w-56 items-baseline gap-1 text-xs leading-4 text-muted-foreground/65"
+      className="inline-flex min-w-0 max-w-56 items-baseline gap-1 text-2xs leading-4 text-muted-foreground"
       data-testid="message-agent-owner"
     >
       <span className="sr-only">
@@ -19,30 +17,22 @@ export function MessageAgentOwner({
       </span>
       {ownerPubkey && ownerLabel ? (
         <>
-          <span
-            aria-hidden="true"
-            className="inline-flex shrink-0 items-baseline gap-1 leading-4"
-          >
-            <Bot className="relative -top-px h-3.5 w-3.5 self-center" />
-            <span>managed by</span>
+          <span aria-hidden="true" className="shrink-0 leading-4">
+            managed by
           </span>
           <UserProfilePopover
             pubkey={ownerPubkey}
             triggerAriaLabel={ownerLabel}
             triggerElement="span"
           >
-            <span className="min-w-0 truncate rounded font-semibold text-foreground/85 hover:text-foreground hover:underline focus-visible:outline-hidden focus-visible:ring-2 focus-visible:ring-ring">
+            <span className="min-w-0 truncate rounded font-medium text-muted-foreground hover:text-foreground hover:underline focus-visible:outline-hidden focus-visible:ring-2 focus-visible:ring-ring">
               {ownerLabel}
             </span>
           </UserProfilePopover>
         </>
       ) : (
-        <span
-          aria-hidden="true"
-          className="inline-flex min-w-0 items-center gap-1"
-        >
-          <Bot className="h-3.5 w-3.5 shrink-0" />
-          <span className="truncate">owner unavailable</span>
+        <span aria-hidden="true" className="min-w-0 truncate">
+          owner unavailable
         </span>
       )}
     </span>
diff --git a/desktop/src/features/messages/ui/MessageHeader.tsx b/desktop/src/features/messages/ui/MessageHeader.tsx
index 64b53fbdd..9f848c2ec 100644
--- a/desktop/src/features/messages/ui/MessageHeader.tsx
+++ b/desktop/src/features/messages/ui/MessageHeader.tsx
@@ -14,7 +14,7 @@ export function MessageHeaderRow({
   return (
     <div
       className={cn(
-        "flex min-w-0 flex-wrap items-baseline gap-x-1.5 gap-y-0 leading-4",
+        "flex min-w-0 flex-wrap items-baseline gap-x-1.5 gap-y-0 leading-message-author",
         className,
       )}
     >
@@ -39,7 +39,7 @@ export function MessageAuthorText({
   return (
     <Component
       className={cn(
-        "truncate text-sm font-bold leading-4 tracking-tight",
+        "truncate text-message font-semibold leading-message-author tracking-normal",
         hoverUnderline && "hover:underline",
         className,
       )}
diff --git a/desktop/src/features/messages/ui/MessageRow.tsx b/desktop/src/features/messages/ui/MessageRow.tsx
index f6be01d71..d2042a8cf 100644
--- a/desktop/src/features/messages/ui/MessageRow.tsx
+++ b/desktop/src/features/messages/ui/MessageRow.tsx
@@ -294,7 +294,7 @@ export const MessageRow = React.memo(
       message.body,
       message.tags,
     );
-    const bodyOffsetClass = emojiOnly ? "mt-1" : "-mt-0.5";
+    const bodyOffsetClass = emojiOnly ? "mt-1" : "mt-conversation-body";
 
     const { nonDmChannelNames: channelNames } = useChannelNavigation();
     const openVideoReviewAt = useOpenVideoReviewAt();
@@ -415,7 +415,7 @@ export const MessageRow = React.memo(
             <Markdown
               channelNames={channelNames}
               className={cn(
-                "max-w-full text-sm",
+                "max-w-full text-message",
                 emojiOnly &&
                   "text-4xl leading-tight [&_p]:leading-tight [&_img[data-custom-emoji]]:h-[1.45em] [&_img[data-custom-emoji]]:align-middle [&_button:has(img[data-custom-emoji])]:align-middle",
               )}
@@ -648,7 +648,7 @@ export const MessageRow = React.memo(
             botIdenticonValue={message.author}
           >
             <button
-              className="truncate rounded leading-4 focus-visible:outline-hidden focus-visible:ring-2 focus-visible:ring-ring"
+              className="truncate rounded leading-message-author focus-visible:outline-hidden focus-visible:ring-2 focus-visible:ring-ring"
               type="button"
             >
               {authorNode}
@@ -881,7 +881,7 @@ export const MessageRow = React.memo(
           className={cn(
             "group/message relative z-10 rounded-2xl transition-colors",
             playEntrance && "motion-enter-conversation",
-            "py-1",
+            "py-conversation-row",
             hoverBackground
               ? "mx-1 px-2 hover:bg-muted/50 focus-within:bg-muted/50"
               : isThreadReplyLayout
diff --git a/desktop/src/features/messages/ui/MessageThreadPanel.tsx b/desktop/src/features/messages/ui/MessageThreadPanel.tsx
index 8f88d8b63..664e2ab72 100644
--- a/desktop/src/features/messages/ui/MessageThreadPanel.tsx
+++ b/desktop/src/features/messages/ui/MessageThreadPanel.tsx
@@ -578,7 +578,7 @@ export function MessageThreadPanel({
           </div>
         ) : (
           <div
-            className={cn(THREAD_PANEL_MESSAGE_GUTTER_CLASS, "pb-1 pt-0")}
+            className={cn(THREAD_PANEL_MESSAGE_GUTTER_CLASS, "pb-2 pt-1")}
             data-testid="message-thread-head"
           >
             <div className="rounded-2xl">
@@ -636,7 +636,7 @@ export function MessageThreadPanel({
 
         {showThreadHeadDivider ? (
           <div
-            className={cn(THREAD_PANEL_MESSAGE_GUTTER_CLASS, "pb-3 pt-2")}
+            className={cn(THREAD_PANEL_MESSAGE_GUTTER_CLASS, "pb-4 pt-3")}
             data-testid="message-thread-head-divider"
           >
             <Separator className="bg-border/60" />
@@ -644,7 +644,7 @@ export function MessageThreadPanel({
         ) : null}
 
         <div
-          className={cn(THREAD_PANEL_MESSAGE_GUTTER_CLASS, "pb-3 pt-0")}
+          className={cn(THREAD_PANEL_MESSAGE_GUTTER_CLASS, "pb-4 pt-0")}
           data-testid="message-thread-replies"
         >
           {threadRepliesPending && !isHuddleTranscript ? (
diff --git a/desktop/src/features/messages/ui/MessageThreadPanelSkeleton.tsx b/desktop/src/features/messages/ui/MessageThreadPanelSkeleton.tsx
index 2d2bb9a84..604ee7ee0 100644
--- a/desktop/src/features/messages/ui/MessageThreadPanelSkeleton.tsx
+++ b/desktop/src/features/messages/ui/MessageThreadPanelSkeleton.tsx
@@ -131,14 +131,14 @@ export function MessageThreadPanelSkeleton({
         }
       >
         <div
-          className={cn(THREAD_PANEL_MESSAGE_GUTTER_CLASS, "pb-1 pt-0")}
+          className={cn(THREAD_PANEL_MESSAGE_GUTTER_CLASS, "pb-2 pt-1")}
           data-testid="message-thread-head-loading"
         >
           <ThreadMessageSkeleton isHead />
         </div>
         <div
           className={cn(
-            "space-y-2.5 pb-3 pt-1",
+            "space-y-2.5 pb-4 pt-2",
             THREAD_PANEL_MESSAGE_GUTTER_CLASS,
           )}
         >
diff --git a/desktop/src/features/messages/ui/MessageTimestamp.tsx b/desktop/src/features/messages/ui/MessageTimestamp.tsx
index ff5394b76..9ad418b07 100644
--- a/desktop/src/features/messages/ui/MessageTimestamp.tsx
+++ b/desktop/src/features/messages/ui/MessageTimestamp.tsx
@@ -34,7 +34,7 @@ export function MessageTimestamp({
         <TooltipTrigger asChild>
           <p
             className={cn(
-              "shrink-0 cursor-default whitespace-nowrap text-xs font-normal leading-4 tabular-nums text-muted-foreground/55",
+              "shrink-0 cursor-default whitespace-nowrap text-message-timestamp font-normal tabular-nums text-muted-foreground/55",
               className,
             )}
             data-testid="message-timestamp"
diff --git a/desktop/src/features/settings/ui/AppearanceSettingsControls.tsx b/desktop/src/features/settings/ui/AppearanceSettingsControls.tsx
index cc5cd31f1..c37ba8f25 100644
--- a/desktop/src/features/settings/ui/AppearanceSettingsControls.tsx
+++ b/desktop/src/features/settings/ui/AppearanceSettingsControls.tsx
@@ -1,3 +1,4 @@
+import type { ReactNode } from "react";
 import { AnimatePresence, motion, useReducedMotion } from "motion/react";
 import { ChevronDown } from "lucide-react";
 import {
@@ -13,6 +14,12 @@ import {
   useLinkPreviewStyle,
   type LinkPreviewStyle,
 } from "@/shared/lib/linkPreviewStylePreference";
+import {
+  previewConversationDensity,
+  setConversationDensity,
+  useConversationDensity,
+  type ConversationDensity,
+} from "@/shared/lib/conversationDensityPreference";
 import {
   ACCENT_COLORS,
   DEFAULT_GLASS_OPACITY,
@@ -31,6 +38,7 @@ import {
 } from "@/shared/ui/dropdown-menu";
 import { Switch } from "@/shared/ui/switch";
 import { SettingsOptionRow } from "./SettingsOptionGroup";
+import { SettingsSegmentedControl } from "./SettingsSegmentedControl";
 
 /** Buzz navigation can use either its production tint or a stronger tab. */
 export function ProminentActiveTabSetting() {
@@ -79,6 +87,127 @@ const LINK_PREVIEW_STYLE_OPTIONS: {
   },
 ];
 
+const CONVERSATION_DENSITY_OPTIONS: readonly {
+  value: ConversationDensity;
+  label: string;
+}[] = [
+  {
+    value: "compact",
+    label: "Compact",
+  },
+  {
+    value: "comfortable",
+    label: "Comfy",
+  },
+  {
+    value: "spacious",
+    label: "Spacious",
+  },
+];
+
+function ConversationDensityPreviewMessage({
+  avatar,
+  author,
+  children,
+  timestamp,
+}: {
+  avatar: string;
+  author: string;
+  children: ReactNode;
+  timestamp: string;
+}) {
+  return (
+    <article className="flex gap-2.5 py-conversation-row">
+      <div className="flex h-8 w-8 shrink-0 items-center justify-center rounded-full bg-muted text-xs font-semibold text-muted-foreground">
+        {avatar}
+      </div>
+      <div className="min-w-0 flex-1">
+        <div className="flex min-w-0 flex-wrap items-baseline gap-x-1.5 leading-message-author">
+          <span className="text-message font-semibold leading-message-author tracking-normal text-foreground">
+            {author}
+          </span>
+          <span className="text-message-timestamp font-normal text-muted-foreground/65">
+            {timestamp}
+          </span>
+        </div>
+        <div className="mt-conversation-body text-message font-normal tracking-normal text-foreground">
+          {children}
+        </div>
+      </div>
+    </article>
+  );
+}
+
+function ConversationDensityPreview() {
+  return (
+    <div className="px-4 py-3" data-testid="conversation-density-preview">
+      <div
+        aria-hidden="true"
+        className="relative overflow-hidden rounded-xl border border-border/65 bg-muted/45"
+        data-testid="conversation-density-preview-surface"
+      >
+        <span className="absolute right-3 top-3 inline-flex rounded-full border border-border/65 bg-background/70 px-2.5 py-1 text-xs font-medium text-muted-foreground">
+          Preview
+        </span>
+        <div className="p-4" data-testid="conversation-density-preview-content">
+          <ConversationDensityPreviewMessage
+            avatar="M"
+            author="Maya"
+            timestamp="9:41"
+          >
+            The revised conversation layout is ready to review.
+          </ConversationDensityPreviewMessage>
+          <ConversationDensityPreviewMessage
+            avatar="T"
+            author="Theo"
+            timestamp="9:43"
+          >
+            <p>
+              I added a longer message so you can compare line height and text
+              spacing.
+            </p>
+            <p className="mt-conversation-paragraph">
+              The same rhythm carries through channels, threads, DMs, and Inbox.
+            </p>
+          </ConversationDensityPreviewMessage>
+        </div>
+      </div>
+    </div>
+  );
+}
+
+/** Message sizing and spacing shared by every conversation surface. */
+export function ConversationDensitySetting() {
+  const density = useConversationDensity();
+
+  return (
+    <>
+      <SettingsOptionRow data-testid="conversation-density-row">
+        <div className="min-w-0">
+          <p className="text-sm font-medium">Conversation density</p>
+          <p
+            className="text-sm font-normal text-muted-foreground/70"
+            data-settings-subcopy
+          >
+            Adjust message size and spacing.
+          </p>
+        </div>
+        <SettingsSegmentedControl
+          className="w-72"
+          legend="Conversation density"
+          onPreviewChange={previewConversationDensity}
+          onValueChange={setConversationDensity}
+          optionTestIdPrefix="conversation-density"
+          options={CONVERSATION_DENSITY_OPTIONS}
+          testId="conversation-density-control"
+          value={density}
+        />
+      </SettingsOptionRow>
+      <ConversationDensityPreview />
+    </>
+  );
+}
+
 export function LinkPreviewStyleSetting() {
   const style = useLinkPreviewStyle();
   const activeOption =
diff --git a/desktop/src/features/settings/ui/SettingsPanels.tsx b/desktop/src/features/settings/ui/SettingsPanels.tsx
index 1dda5bc1c..4896c207b 100644
--- a/desktop/src/features/settings/ui/SettingsPanels.tsx
+++ b/desktop/src/features/settings/ui/SettingsPanels.tsx
@@ -55,6 +55,7 @@ import {
 import { appearanceCommunityLabel } from "../lib/appearanceScopeCopy";
 import {
   AccentPickerContent,
+  ConversationDensitySetting,
   GlassBackgroundSetting,
   LinkPreviewStyleSetting,
   ProminentActiveTabSetting,
@@ -70,6 +71,7 @@ import { NotificationSettingsCard } from "./NotificationSettingsCard";
 import { AgentsSettingsPanel } from "./AgentsSettingsPanel";
 import { HostedCommunitiesSettingsCard } from "./HostedCommunitiesSettingsCard";
 import { SettingsOptionGroup, SettingsOptionRow } from "./SettingsOptionGroup";
+import { SettingsSegmentedControl } from "./SettingsSegmentedControl";
 import { ProfileSettingsCard } from "./ProfileSettingsCard";
 import { UpdateChecker } from "../UpdateChecker";
 import { SettingsSectionHeader } from "./SettingsSectionHeader";
@@ -395,9 +397,9 @@ function SingleThemeTile({
 type AppearanceMode = "system" | "light" | "dark";
 
 const APPEARANCE_MODE_OPTIONS = [
-  { mode: "system" as const, label: "System", Icon: SunMoon },
-  { mode: "light" as const, label: "Light", Icon: Sun },
-  { mode: "dark" as const, label: "Dark", Icon: Moon },
+  { value: "system" as const, label: "System", Icon: SunMoon },
+  { value: "light" as const, label: "Light", Icon: Sun },
+  { value: "dark" as const, label: "Dark", Icon: Moon },
 ] as const;
 
 // Reveal/hide motion for the accent picker: a small translate + opacity fade.
@@ -670,39 +672,15 @@ function ThemeSettingsCard() {
                 Follow your system or choose a light or dark appearance.
               </p>
             </div>
-            <fieldset
-              className="relative isolate grid h-8 w-[15rem] shrink-0 grid-cols-3 overflow-hidden rounded-md bg-muted/45 p-0.5"
-              data-testid="appearance-color-mode-control"
-            >
-              <legend className="sr-only">Color mode</legend>
-              <div
-                aria-hidden="true"
-                className="absolute bottom-0.5 left-0.5 top-0.5 z-0 rounded-md bg-background shadow-sm transition-transform duration-[250ms] ease-out motion-reduce:transition-none"
-                data-testid="appearance-color-mode-indicator"
-                style={{
-                  transform: `translateX(${APPEARANCE_MODE_OPTIONS.findIndex((option) => option.mode === selectedMode) * 100}%)`,
-                  width: "calc((100% - 4px) / 3)",
-                }}
-              />
-              {APPEARANCE_MODE_OPTIONS.map(({ mode, label, Icon }) => (
-                <button
-                  aria-pressed={selectedMode === mode}
-                  className={cn(
-                    "relative z-10 flex h-full items-center justify-center gap-1.5 rounded-md bg-transparent px-2.5 text-xs font-medium transition-colors duration-[250ms] ease-out focus-visible:outline-hidden focus-visible:ring-2 focus-visible:ring-ring motion-reduce:transition-none",
-                    selectedMode === mode
-                      ? "text-foreground"
-                      : "text-muted-foreground hover:text-foreground",
-                  )}
-                  data-testid={`appearance-mode-${mode}`}
-                  key={mode}
-                  onClick={() => handleModeSelect(mode)}
-                  type="button"
-                >
-                  <Icon className="h-3.5 w-3.5" />
-                  {label}
-                </button>
-              ))}
-            </fieldset>
+            <SettingsSegmentedControl
+              indicatorTestId="appearance-color-mode-indicator"
+              legend="Color mode"
+              onValueChange={handleModeSelect}
+              optionTestIdPrefix="appearance-mode"
+              options={APPEARANCE_MODE_OPTIONS}
+              testId="appearance-color-mode-control"
+              value={selectedMode}
+            />
           </SettingsOptionRow>
 
           <SettingsOptionRow data-testid="theme-style-row">
@@ -804,6 +782,7 @@ function ThemeSettingsCard() {
           data-testid="appearance-preferences-card"
           title="Preferences"
         >
+          <ConversationDensitySetting />
           <LinkPreviewStyleSetting />
           <ThreadLayoutSetting />
         </SettingsOptionGroup>
diff --git a/desktop/src/features/settings/ui/SettingsSegmentedControl.tsx b/desktop/src/features/settings/ui/SettingsSegmentedControl.tsx
new file mode 100644
index 000000000..097f3cba3
--- /dev/null
+++ b/desktop/src/features/settings/ui/SettingsSegmentedControl.tsx
@@ -0,0 +1,185 @@
+import * as React from "react";
+
+import { cn } from "@/shared/lib/cn";
+
+type SegmentOption<Value extends string> = {
+  value: Value;
+  label: string;
+  Icon?: React.ComponentType<{ className?: string }>;
+};
+
+export function SettingsSegmentedControl<Value extends string>({
+  className,
+  indicatorTestId,
+  legend,
+  onPreviewChange,
+  onValueChange,
+  optionTestIdPrefix,
+  options,
+  testId,
+  value,
+}: {
+  className?: string;
+  indicatorTestId?: string;
+  legend: string;
+  onPreviewChange?: (value: Value | null) => void;
+  onValueChange: (value: Value) => void;
+  optionTestIdPrefix: string;
+  options: readonly SegmentOption<Value>[];
+  testId: string;
+  value: Value;
+}) {
+  const [previewValue, setPreviewValue] = React.useState<Value | null>(null);
+  const pointerStartXRef = React.useRef<number | null>(null);
+  const pointerStartValueRef = React.useRef<Value | null>(null);
+  const scrubValueRef = React.useRef<Value | null>(null);
+  const skipPointerClickRef = React.useRef(false);
+  const displayedValue = previewValue ?? value;
+  const selectedIndex = Math.max(
+    0,
+    options.findIndex((option) => option.value === displayedValue),
+  );
+
+  const getValueAtPointer = React.useCallback(
+    (element: HTMLFieldSetElement, clientX: number): Value => {
+      const bounds = element.getBoundingClientRect();
+      const position = Math.max(
+        0,
+        Math.min(bounds.width - 1, clientX - bounds.left),
+      );
+      const index = Math.min(
+        options.length - 1,
+        Math.floor((position / bounds.width) * options.length),
+      );
+      return options[index]?.value ?? value;
+    },
+    [options, value],
+  );
+
+  const preview = React.useCallback(
+    (nextValue: Value | null) => {
+      scrubValueRef.current = nextValue;
+      setPreviewValue(nextValue);
+      onPreviewChange?.(nextValue);
+    },
+    [onPreviewChange],
+  );
+
+  React.useEffect(
+    () => () => {
+      onPreviewChange?.(null);
+    },
+    [onPreviewChange],
+  );
+
+  const handlePointerDown = (
+    event: React.PointerEvent<HTMLFieldSetElement>,
+  ) => {
+    if (!onPreviewChange || event.button !== 0) return;
+    event.currentTarget.setPointerCapture(event.pointerId);
+    pointerStartXRef.current = event.clientX;
+    pointerStartValueRef.current = getValueAtPointer(
+      event.currentTarget,
+      event.clientX,
+    );
+    scrubValueRef.current = null;
+    skipPointerClickRef.current = true;
+    event.preventDefault();
+  };
+
+  const handlePointerMove = (
+    event: React.PointerEvent<HTMLFieldSetElement>,
+  ) => {
+    if (!event.currentTarget.hasPointerCapture(event.pointerId)) return;
+    const nextValue = getValueAtPointer(event.currentTarget, event.clientX);
+    const pointerStartX = pointerStartXRef.current;
+    const pointerStartValue = pointerStartValueRef.current;
+    const crossedDragThreshold =
+      pointerStartX != null && Math.abs(event.clientX - pointerStartX) >= 4;
+    if (
+      scrubValueRef.current == null &&
+      !crossedDragThreshold &&
+      nextValue === pointerStartValue
+    ) {
+      return;
+    }
+    if (nextValue !== scrubValueRef.current) preview(nextValue);
+  };
+
+  const handlePointerUp = (event: React.PointerEvent<HTMLFieldSetElement>) => {
+    if (!event.currentTarget.hasPointerCapture(event.pointerId)) return;
+    const nextValue = getValueAtPointer(event.currentTarget, event.clientX);
+    event.currentTarget.releasePointerCapture(event.pointerId);
+    pointerStartXRef.current = null;
+    pointerStartValueRef.current = null;
+    onValueChange(nextValue);
+    preview(null);
+    globalThis.setTimeout(() => {
+      skipPointerClickRef.current = false;
+    }, 0);
+  };
+
+  const handlePointerCancel = (
+    event: React.PointerEvent<HTMLFieldSetElement>,
+  ) => {
+    if (!event.currentTarget.hasPointerCapture(event.pointerId)) return;
+    event.currentTarget.releasePointerCapture(event.pointerId);
+    pointerStartXRef.current = null;
+    pointerStartValueRef.current = null;
+    skipPointerClickRef.current = false;
+    preview(null);
+  };
+
+  return (
+    <fieldset
+      className={cn(
+        "relative isolate grid h-8 w-60 shrink-0 grid-cols-3 overflow-hidden rounded-md bg-muted/45 p-0.5",
+        onPreviewChange && "touch-none select-none cursor-ew-resize",
+        className,
+      )}
+      data-testid={testId}
+      onPointerCancel={handlePointerCancel}
+      onPointerDown={handlePointerDown}
+      onPointerMove={handlePointerMove}
+      onPointerUp={handlePointerUp}
+    >
+      <legend className="sr-only">{legend}</legend>
+      <div
+        aria-hidden="true"
+        className={cn(
+          "absolute bottom-0.5 left-0.5 top-0.5 z-0 rounded-md bg-background shadow-sm transition-transform duration-200 ease-in-out motion-reduce:transition-none",
+          previewValue && "duration-0",
+        )}
+        data-testid={indicatorTestId ?? `${testId}-indicator`}
+        style={{
+          transform: `translateX(${selectedIndex * 100}%)`,
+          width: `calc((100% - 0.25rem) / ${options.length})`,
+        }}
+      />
+      {options.map(({ value: optionValue, label, Icon }) => (
+        <button
+          aria-pressed={value === optionValue}
+          className={cn(
+            "relative z-10 flex h-full items-center justify-center gap-1.5 rounded-md bg-transparent px-2.5 text-xs font-medium transition-colors duration-150 ease-out focus-visible:outline-hidden focus-visible:ring-2 focus-visible:ring-ring motion-reduce:transition-none",
+            displayedValue === optionValue
+              ? "text-foreground"
+              : "text-muted-foreground hover:text-foreground",
+          )}
+          data-testid={`${optionTestIdPrefix}-${optionValue}`}
+          key={optionValue}
+          onClick={(event) => {
+            if (event.detail > 0 && skipPointerClickRef.current) {
+              skipPointerClickRef.current = false;
+              return;
+            }
+            onValueChange(optionValue);
+          }}
+          type="button"
+        >
+          {Icon ? <Icon className="h-3.5 w-3.5" /> : null}
+          {label}
+        </button>
+      ))}
+    </fieldset>
+  );
+}
diff --git a/desktop/src/main.tsx b/desktop/src/main.tsx
index bbb4c5fa4..91b002eef 100644
--- a/desktop/src/main.tsx
+++ b/desktop/src/main.tsx
@@ -3,7 +3,8 @@ import ReactDOM from "react-dom/client";
 import { App } from "@/app/App";
 import { RootErrorBoundary } from "@/app/RootErrorBoundary";
 import { NostrBindConsentDialog } from "@/features/profile/ui/NostrBindConsentDialog";
-import "@fontsource-variable/inter/wght.css";
+import "@fontsource-variable/inter/opsz.css";
+import "@fontsource-variable/inter/opsz-italic.css";
 import "@fontsource/jetbrains-mono/400.css";
 import "@fontsource/jetbrains-mono/700.css";
 import "@/shared/styles/globals.css";
@@ -19,6 +20,7 @@ import { Toaster } from "@/shared/ui/sonner";
 import { TooltipProvider } from "@/shared/ui/tooltip";
 import { recoverLocalStorageQuotaOnStartup } from "@/shared/lib/localStorageQuota";
 import { startLocalStorageSweep } from "@/shared/lib/localStorageSweep";
+import { initializeConversationDensityPreference } from "@/shared/lib/conversationDensityPreference";
 
 type E2eWindow = Window & {
   __BUZZ_E2E__?: unknown;
@@ -123,6 +125,7 @@ async function bootstrap() {
   resetDevWebviewStateFromUrl();
   configureDevE2eBridgeFromUrl();
   recoverLocalStorageQuotaOnStartup();
+  initializeConversationDensityPreference();
   startLocalStorageSweep();
   await installE2eBridgeIfConfigured();
   await migrateLegacyCommunityStorageBeforeRender();
diff --git a/desktop/src/shared/lib/cn.ts b/desktop/src/shared/lib/cn.ts
index a5ef19350..79fe7d289 100644
--- a/desktop/src/shared/lib/cn.ts
+++ b/desktop/src/shared/lib/cn.ts
@@ -1,6 +1,18 @@
 import { clsx, type ClassValue } from "clsx";
-import { twMerge } from "tailwind-merge";
+import { extendTailwindMerge } from "tailwind-merge";
+
+const mergeClassNames = extendTailwindMerge({
+  extend: {
+    classGroups: {
+      "font-size": [
+        {
+          text: ["message", "message-timestamp"],
+        },
+      ],
+    },
+  },
+});
 
 export function cn(...inputs: ClassValue[]) {
-  return twMerge(clsx(inputs));
+  return mergeClassNames(clsx(inputs));
 }
diff --git a/desktop/src/shared/lib/conversationDensityPreference.test.mjs b/desktop/src/shared/lib/conversationDensityPreference.test.mjs
new file mode 100644
index 000000000..4a51b0f11
--- /dev/null
+++ b/desktop/src/shared/lib/conversationDensityPreference.test.mjs
@@ -0,0 +1,59 @@
+import assert from "node:assert/strict";
+import test from "node:test";
+
+const values = new Map();
+const attributes = new Map();
+
+globalThis.localStorage = {
+  getItem: (key) => values.get(key) ?? null,
+  setItem: (key, value) => values.set(key, String(value)),
+};
+globalThis.document = {
+  documentElement: {
+    setAttribute: (name, value) => attributes.set(name, value),
+  },
+};
+
+const preference = await import("./conversationDensityPreference.ts");
+
+test("defaults invalid and missing conversation densities to comfortable", () => {
+  assert.equal(preference.parseConversationDensity(null), "comfortable");
+  assert.equal(preference.parseConversationDensity("dense"), "comfortable");
+  assert.equal(preference.parseConversationDensity("compact"), "compact");
+  assert.equal(
+    preference.parseConversationDensity("comfortable"),
+    "comfortable",
+  );
+  assert.equal(preference.parseConversationDensity("spacious"), "spacious");
+});
+
+test("persists and applies the selected conversation density", () => {
+  preference.setConversationDensity("compact");
+  assert.equal(preference.getConversationDensity(), "compact");
+  assert.equal(
+    values.get(preference.CONVERSATION_DENSITY_STORAGE_KEY),
+    "compact",
+  );
+  assert.equal(attributes.get("data-conversation-density"), "compact");
+});
+
+test("previews a density without changing the saved preference", () => {
+  preference.setConversationDensity("compact");
+  preference.previewConversationDensity("spacious");
+  assert.equal(preference.getConversationDensity(), "compact");
+  assert.equal(
+    values.get(preference.CONVERSATION_DENSITY_STORAGE_KEY),
+    "compact",
+  );
+  assert.equal(attributes.get("data-conversation-density"), "spacious");
+
+  preference.previewConversationDensity(null);
+  assert.equal(attributes.get("data-conversation-density"), "compact");
+});
+
+test("initializes from the persisted conversation density", () => {
+  values.set(preference.CONVERSATION_DENSITY_STORAGE_KEY, "spacious");
+  preference.initializeConversationDensityPreference();
+  assert.equal(preference.getConversationDensity(), "spacious");
+  assert.equal(attributes.get("data-conversation-density"), "spacious");
+});
diff --git a/desktop/src/shared/lib/conversationDensityPreference.ts b/desktop/src/shared/lib/conversationDensityPreference.ts
new file mode 100644
index 000000000..5477b8062
--- /dev/null
+++ b/desktop/src/shared/lib/conversationDensityPreference.ts
@@ -0,0 +1,84 @@
+import * as React from "react";
+
+/** Device-level message sizing and spacing used across conversation surfaces. */
+export type ConversationDensity = "compact" | "comfortable" | "spacious";
+
+export const CONVERSATION_DENSITY_STORAGE_KEY =
+  "buzz.appearance.conversationDensity";
+export const DEFAULT_CONVERSATION_DENSITY: ConversationDensity = "comfortable";
+
+const listeners = new Set<() => void>();
+let conversationDensity: ConversationDensity = DEFAULT_CONVERSATION_DENSITY;
+
+export function parseConversationDensity(
+  value: string | null | undefined,
+): ConversationDensity {
+  return value === "compact" || value === "comfortable" || value === "spacious"
+    ? value
+    : DEFAULT_CONVERSATION_DENSITY;
+}
+
+function readStoredConversationDensity(): ConversationDensity {
+  try {
+    return parseConversationDensity(
+      globalThis.localStorage?.getItem(CONVERSATION_DENSITY_STORAGE_KEY),
+    );
+  } catch {
+    return DEFAULT_CONVERSATION_DENSITY;
+  }
+}
+
+function applyConversationDensity(density: ConversationDensity): void {
+  globalThis.document?.documentElement?.setAttribute(
+    "data-conversation-density",
+    density,
+  );
+}
+
+function notifyListeners(): void {
+  for (const listener of listeners) listener();
+}
+
+/** Apply the persisted preference before React renders to avoid a layout jump. */
+export function initializeConversationDensityPreference(): void {
+  const nextDensity = readStoredConversationDensity();
+  const changed = nextDensity !== conversationDensity;
+  conversationDensity = nextDensity;
+  applyConversationDensity(nextDensity);
+  if (changed) notifyListeners();
+}
+
+function subscribe(listener: () => void): () => void {
+  listeners.add(listener);
+  return () => listeners.delete(listener);
+}
+
+export function getConversationDensity(): ConversationDensity {
+  return conversationDensity;
+}
+
+export function setConversationDensity(density: ConversationDensity): void {
+  conversationDensity = density;
+  applyConversationDensity(density);
+  try {
+    globalThis.localStorage?.setItem(CONVERSATION_DENSITY_STORAGE_KEY, density);
+  } catch {
+    // Persistence is best-effort; the live preference still applies.
+  }
+  notifyListeners();
+}
+
+/** Temporarily apply a density without changing the saved preference. */
+export function previewConversationDensity(
+  density: ConversationDensity | null,
+): void {
+  applyConversationDensity(density ?? conversationDensity);
+}
+
+export function useConversationDensity(): ConversationDensity {
+  return React.useSyncExternalStore(
+    subscribe,
+    getConversationDensity,
+    () => DEFAULT_CONVERSATION_DENSITY,
+  );
+}
diff --git a/desktop/src/shared/styles/globals/composer.css b/desktop/src/shared/styles/globals/composer.css
index 0af4a59b4..2ee690e41 100644
--- a/desktop/src/shared/styles/globals/composer.css
+++ b/desktop/src/shared/styles/globals/composer.css
@@ -93,10 +93,9 @@
 }
 
 .rich-text-composer .tiptap {
+  @apply text-message font-normal tracking-normal;
   outline: none;
   min-height: 1lh;
-  font-size: var(--text-sm);
-  line-height: var(--text-sm--line-height);
 }
 
 .rich-text-composer .tiptap p {
diff --git a/desktop/src/shared/styles/globals/theme.css b/desktop/src/shared/styles/globals/theme.css
index 171f8c0b2..91de1ed1e 100644
--- a/desktop/src/shared/styles/globals/theme.css
+++ b/desktop/src/shared/styles/globals/theme.css
@@ -2,6 +2,20 @@
   :root {
     /* Catppuccin Latte (mauve accent) */
     --radius: 0.625rem;
+    /*
+     * Comfortable conversation rhythm for channels, DMs, threads, Inbox, and
+     * the composer. The Appearance preference overrides this complete scale
+     * below, while rem units keep Cmd +/- text scaling intact.
+     */
+    --conversation-message-font-size: 0.9375rem;
+    --conversation-message-line-height: 1.25rem;
+    --conversation-author-line-height: 1.0625rem;
+    --conversation-body-gap: 0.125rem;
+    --conversation-row-padding-block: 0.375rem;
+    --conversation-paragraph-gap: 0.5rem;
+    --conversation-list-item-gap: 0.375rem;
+    --conversation-timestamp-font-size: 0.6875rem;
+    --conversation-timestamp-line-height: 1rem;
     --background: 220 23.08% 94.9%;
     --foreground: 234 16.02% 35.49%;
     --card: 220 23.08% 94.9%;
@@ -65,6 +79,30 @@
     --buzz-hosted-community-identity-bg: 255 255 255;
   }
 
+  :root[data-conversation-density="compact"] {
+    --conversation-message-font-size: 0.875rem;
+    --conversation-message-line-height: 1.1875rem;
+    --conversation-author-line-height: 1rem;
+    --conversation-body-gap: 0rem;
+    --conversation-row-padding-block: 0.25rem;
+    --conversation-paragraph-gap: 0.375rem;
+    --conversation-list-item-gap: 0.25rem;
+    --conversation-timestamp-font-size: 0.625rem;
+    --conversation-timestamp-line-height: 0.875rem;
+  }
+
+  :root[data-conversation-density="spacious"] {
+    --conversation-message-font-size: 1rem;
+    --conversation-message-line-height: 1.375rem;
+    --conversation-author-line-height: 1.125rem;
+    --conversation-body-gap: 0.25rem;
+    --conversation-row-padding-block: 0.5rem;
+    --conversation-paragraph-gap: 0.625rem;
+    --conversation-list-item-gap: 0.5rem;
+    --conversation-timestamp-font-size: 0.75rem;
+    --conversation-timestamp-line-height: 1.125rem;
+  }
+
   .dark {
     /* Catppuccin Macchiato (mauve accent) */
     --radius: 0.625rem;
@@ -153,6 +191,10 @@
   body {
     @apply bg-background text-foreground antialiased;
     font-family: "Inter Variable", Inter, "Avenir Next", "Segoe UI", sans-serif;
+    font-synthesis-weight: none;
+    font-variant-emoji: unicode;
+    font-variant-ligatures: no-contextual;
+    text-rendering: optimizeLegibility;
   }
 
   /*
diff --git a/desktop/src/shared/ui/markdown.tsx b/desktop/src/shared/ui/markdown.tsx
index 433a8ce6e..742f702ae 100644
--- a/desktop/src/shared/ui/markdown.tsx
+++ b/desktop/src/shared/ui/markdown.tsx
@@ -1893,10 +1893,10 @@ function MarkdownInner({
       className={cn(
         MESSAGE_MARKDOWN_CLASS,
         [
-          "max-w-none wrap-anywhere text-sm leading-5 text-foreground",
+          "max-w-none wrap-anywhere text-message font-normal tracking-normal text-foreground",
           "[&>*:first-child]:mt-0 [&>*:last-child]:mb-0",
           "[&>*+*]:mt-3",
-          "[&>p+p]:mt-1.5",
+          "[&>p+p]:mt-conversation-paragraph [&>ol]:space-y-conversation-list [&>ul]:space-y-conversation-list",
           "[&>*+h1]:mt-3.5 [&>*+h2]:mt-3.5 [&>*+h3]:mt-3.5 [&>*+h4]:mt-3.5 [&>*+h5]:mt-3.5 [&>*+h6]:mt-3.5",
           "[&>h1+*]:mt-0.5 [&>h2+*]:mt-0.5 [&>h3+*]:mt-0.5 [&>h4+*]:mt-0.5 [&>h5+*]:mt-0.5 [&>h6+*]:mt-0.5",
           "[&>h1+h2]:mt-1.5! [&>h2+h3]:mt-1.5! [&>h3+h4]:mt-1.5! [&>h4+h5]:mt-1.5! [&>h5+h6]:mt-1.5!",
diff --git a/desktop/tailwind.config.js b/desktop/tailwind.config.js
index 8905fc16c..c663a2ac3 100644
--- a/desktop/tailwind.config.js
+++ b/desktop/tailwind.config.js
@@ -11,11 +11,25 @@ export default {
         "2xs": "0.6875rem", // 11px — meta-text workhorse (timestamps, badges)
         "3xs": "0.5rem", // 8px — tiny glyphs / micro labels
         badge: "0.625rem", // 10px — compact status badges
+        // Shared channel, DM, thread, and composer type. Backed by CSS
+        // variables so the Appearance preference can change the complete
+        // conversation rhythm without branching individual components.
+        message: [
+          "var(--conversation-message-font-size)",
+          { lineHeight: "var(--conversation-message-line-height)" },
+        ],
+        "message-timestamp": [
+          "var(--conversation-timestamp-font-size)",
+          { lineHeight: "var(--conversation-timestamp-line-height)" },
+        ],
         // 40px — onboarding page titles (tightened tracking for large display type)
         title: ["2.5rem", { lineHeight: "1.15", letterSpacing: "-0.02em" }],
         // 36px — the backup-step private key, shown large in monospace
         "nsec-key": ["2.25rem", { lineHeight: "1.3" }],
       },
+      lineHeight: {
+        "message-author": "var(--conversation-author-line-height)",
+      },
       boxShadow: {
         "content-edge": "-1px -1px 0 0 hsl(var(--sidebar-border) / 0.45)",
         // Edge + elevation for a surface anchored to the right of the content
@@ -36,6 +50,10 @@ export default {
       },
       spacing: {
         4.5: "1.125rem",
+        "conversation-body": "var(--conversation-body-gap)",
+        "conversation-list": "var(--conversation-list-item-gap)",
+        "conversation-paragraph": "var(--conversation-paragraph-gap)",
+        "conversation-row": "var(--conversation-row-padding-block)",
       },
       fontFamily: {
         sans: [
diff --git a/desktop/tests/e2e/buzz-theme-screenshots.spec.ts b/desktop/tests/e2e/buzz-theme-screenshots.spec.ts
index a52181429..cd3a26264 100644
--- a/desktop/tests/e2e/buzz-theme-screenshots.spec.ts
+++ b/desktop/tests/e2e/buzz-theme-screenshots.spec.ts
@@ -8,6 +8,7 @@ const THEME_STORAGE_KEY = "buzz-theme";
 const GLASS_BACKGROUND_STORAGE_KEY = "buzz-glass-background";
 const GLASS_OPACITY_STORAGE_KEY = "buzz-glass-opacity";
 const PROMINENT_ACTIVE_TAB_STORAGE_KEY = "buzz-prominent-active-tab";
+const CONVERSATION_DENSITY_STORAGE_KEY = "buzz.appearance.conversationDensity";
 const MOCK_PUBKEY = "deadbeef".repeat(8);
 const GENERAL_CHANNEL_ID = "9a1657ac-f7aa-5db0-b632-d8bbeb6dfb50";
 
@@ -616,6 +617,329 @@ test("appearance groups theme and preferences into labeled rows", async ({
   ).toBeLessThanOrEqual(0.5);
 });
 
+test("conversation density applies and persists all three scales", async ({
+  page,
+}) => {
+  await seedTheme(page, "buzz");
+  await installMockBridge(page);
+  await openAppearance(page, "light");
+
+  const root = page.locator("html");
+  const control = page.getByTestId("conversation-density-control");
+  const compact = page.getByTestId("conversation-density-compact");
+  const comfortable = page.getByTestId("conversation-density-comfortable");
+  const spacious = page.getByTestId("conversation-density-spacious");
+  const indicator = page.getByTestId("conversation-density-control-indicator");
+  const preview = page.getByTestId("conversation-density-preview");
+  const previewSurface = page.getByTestId(
+    "conversation-density-preview-surface",
+  );
+  const previewContent = page.getByTestId(
+    "conversation-density-preview-content",
+  );
+  const previewChip = preview.getByText("Preview");
+  const firstPreviewMessage = previewSurface.locator("article").first();
+  const previewMessage = preview.getByText(
+    "The revised conversation layout is ready to review.",
+  );
+  const previewTimestamp = preview.getByText("9:41");
+  const description = page
+    .getByTestId("conversation-density-row")
+    .locator("[data-settings-subcopy]");
+  const readScale = () =>
+    root.evaluate((element) => {
+      const style = window.getComputedStyle(element);
+      return {
+        authorLineHeight: Number.parseFloat(
+          style.getPropertyValue("--conversation-author-line-height"),
+        ),
+        bodyGap: Number.parseFloat(
+          style.getPropertyValue("--conversation-body-gap"),
+        ),
+        fontSize: Number.parseFloat(
+          style.getPropertyValue("--conversation-message-font-size"),
+        ),
+        lineHeight: Number.parseFloat(
+          style.getPropertyValue("--conversation-message-line-height"),
+        ),
+        paragraphGap: Number.parseFloat(
+          style.getPropertyValue("--conversation-paragraph-gap"),
+        ),
+        rowPadding: Number.parseFloat(
+          style.getPropertyValue("--conversation-row-padding-block"),
+        ),
+        timestampFontSize: Number.parseFloat(
+          style.getPropertyValue("--conversation-timestamp-font-size"),
+        ),
+        timestampLineHeight: Number.parseFloat(
+          style.getPropertyValue("--conversation-timestamp-line-height"),
+        ),
+      };
+    });
+  const readSettingsScale = () =>
+    page.getByTestId("conversation-density-row").evaluate((element) => {
+      const rowStyle = window.getComputedStyle(element);
+      const label = element.querySelector("p");
+      if (!label) throw new Error("Conversation density label is missing");
+      const labelStyle = window.getComputedStyle(label);
+      return {
+        fontSize: labelStyle.fontSize,
+        lineHeight: labelStyle.lineHeight,
+        minHeight: rowStyle.minHeight,
+        paddingBlock: rowStyle.paddingTop,
+      };
+    });
+  const readPreviewTimestampScale = () =>
+    previewTimestamp.evaluate((element) => {
+      const style = window.getComputedStyle(element);
+      return [style.fontSize, style.lineHeight];
+    });
+  const readSettingsChromeScale = () =>
+    Promise.all([
+      page
+        .getByRole("heading", { name: "Appearance" })
+        .evaluate((element) => window.getComputedStyle(element).fontSize),
+      page
+        .getByTestId("settings-nav-appearance")
+        .evaluate((element) => window.getComputedStyle(element).fontSize),
+      page
+        .getByRole("heading", { name: "Preferences" })
+        .evaluate((element) => window.getComputedStyle(element).fontSize),
+    ]);
+
+  await expect(
+    page.getByRole("group", { name: "Conversation density" }),
+  ).toBeVisible();
+  await expect(control).toHaveAccessibleName("Conversation density");
+  await expect(comfortable).toHaveText("Comfy");
+  await expect(preview).toContainText("Preview");
+  await expect(preview).not.toContainText("Message #design");
+  await expect(comfortable).toHaveAttribute("aria-pressed", "true");
+  await expect(description).toHaveText("Adjust message size and spacing.");
+  await expect.poll(readScale).toEqual({
+    authorLineHeight: 1.0625,
+    bodyGap: 0.125,
+    fontSize: 0.9375,
+    lineHeight: 1.25,
+    paragraphGap: 0.5,
+    rowPadding: 0.375,
+    timestampFontSize: 0.6875,
+    timestampLineHeight: 1,
+  });
+  await expect
+    .poll(() =>
+      Promise.all([
+        control.evaluate((element) => element.getBoundingClientRect().width),
+        page
+          .getByTestId("appearance-color-mode-control")
+          .evaluate((element) => element.getBoundingClientRect().width),
+      ]),
+    )
+    .toEqual([288, 240]);
+  await expect
+    .poll(() =>
+      previewMessage.evaluate((element) => {
+        const style = window.getComputedStyle(element);
+        return [style.fontSize, style.lineHeight];
+      }),
+    )
+    .toEqual(["15px", "20px"]);
+  await expect.poll(readSettingsScale).toEqual({
+    fontSize: "14px",
+    lineHeight: "20px",
+    minHeight: "64px",
+    paddingBlock: "12px",
+  });
+  await expect.poll(readPreviewTimestampScale).toEqual(["11px", "16px"]);
+  await expect.poll(readSettingsChromeScale).toEqual(["24px", "14px", "18px"]);
+  await expect(indicator).toHaveCSS("transition-duration", "0.2s");
+  await expect(indicator).toHaveCSS("transition-property", /transform/);
+  await expect
+    .poll(async () => {
+      const [previewBackground, controlBackground] = await Promise.all([
+        previewSurface.evaluate(
+          (element) => window.getComputedStyle(element).backgroundColor,
+        ),
+        control.evaluate(
+          (element) => window.getComputedStyle(element).backgroundColor,
+        ),
+      ]);
+      return previewBackground === controlBackground;
+    })
+    .toBe(true);
+  const previewSurfaceBox = await previewSurface.boundingBox();
+  const previewChipBox = await previewChip.boundingBox();
+  const firstPreviewMessageBox = await firstPreviewMessage.boundingBox();
+  expect(previewSurfaceBox).not.toBeNull();
+  expect(previewChipBox).not.toBeNull();
+  expect(firstPreviewMessageBox).not.toBeNull();
+  if (!previewSurfaceBox || !previewChipBox || !firstPreviewMessageBox) {
+    throw new Error("Conversation density preview geometry is missing");
+  }
+  const previewChipRightInset =
+    previewSurfaceBox.x +
+    previewSurfaceBox.width -
+    (previewChipBox.x + previewChipBox.width);
+  expect(previewChipRightInset).toBeGreaterThanOrEqual(12);
+  expect(previewChipRightInset).toBeLessThanOrEqual(13);
+  const previewChipTopInset = previewChipBox.y - previewSurfaceBox.y;
+  expect(previewChipTopInset).toBeGreaterThanOrEqual(12);
+  expect(previewChipTopInset).toBeLessThanOrEqual(13);
+  await expect(previewContent).toHaveCSS("padding-top", "16px");
+  await expect(previewContent).toHaveCSS("padding-right", "16px");
+  await expect(previewContent).toHaveCSS("padding-bottom", "16px");
+  await expect(previewContent).toHaveCSS("padding-left", "16px");
+  expect(firstPreviewMessageBox.x - previewSurfaceBox.x).toBeGreaterThanOrEqual(
+    16,
+  );
+  expect(firstPreviewMessageBox.x - previewSurfaceBox.x).toBeLessThanOrEqual(
+    18,
+  );
+  expect(firstPreviewMessageBox.y - previewSurfaceBox.y).toBeGreaterThanOrEqual(
+    16,
+  );
+  expect(firstPreviewMessageBox.y - previewSurfaceBox.y).toBeLessThanOrEqual(
+    18,
+  );
+  await expect(previewChip).toHaveCSS("padding-top", "4px");
+  await expect(previewChip).toHaveCSS("padding-bottom", "4px");
+
+  await indicator.evaluate((element) => {
+    element.addEventListener(
+      "transitionrun",
+      () => element.setAttribute("data-transition-ran", "true"),
+      { once: true },
+    );
+  });
+
+  await compact.click();
+  await expect(indicator).toHaveAttribute("data-transition-ran", "true");
+  await expect(root).toHaveAttribute("data-conversation-density", "compact");
+  await expect(compact).toHaveAttribute("aria-pressed", "true");
+  await expect(description).toHaveText("Adjust message size and spacing.");
+  await expect
+    .poll(() =>
+      page.evaluate(
+        (key) => window.localStorage.getItem(key),
+        CONVERSATION_DENSITY_STORAGE_KEY,
+      ),
+    )
+    .toBe("compact");
+  await expect.poll(readScale).toEqual({
+    authorLineHeight: 1,
+    bodyGap: 0,
+    fontSize: 0.875,
+    lineHeight: 1.1875,
+    paragraphGap: 0.375,
+    rowPadding: 0.25,
+    timestampFontSize: 0.625,
+    timestampLineHeight: 0.875,
+  });
+  await expect.poll(readSettingsScale).toEqual({
+    fontSize: "14px",
+    lineHeight: "20px",
+    minHeight: "64px",
+    paddingBlock: "12px",
+  });
+  await expect.poll(readPreviewTimestampScale).toEqual(["10px", "14px"]);
+  await expect.poll(readSettingsChromeScale).toEqual(["24px", "14px", "18px"]);
+  await waitForAnimations(page);
+  await page.getByTestId("appearance-preferences-card").screenshot({
+    path: `${SHOTS}/15-conversation-density-compact.png`,
+  });
+
+  await spacious.click();
+  await expect(root).toHaveAttribute("data-conversation-density", "spacious");
+  await expect(spacious).toHaveAttribute("aria-pressed", "true");
+  await expect(description).toHaveText("Adjust message size and spacing.");
+  await expect.poll(readScale).toEqual({
+    authorLineHeight: 1.125,
+    bodyGap: 0.25,
+    fontSize: 1,
+    lineHeight: 1.375,
+    paragraphGap: 0.625,
+    rowPadding: 0.5,
+    timestampFontSize: 0.75,
+    timestampLineHeight: 1.125,
+  });
+  await expect.poll(readSettingsScale).toEqual({
+    fontSize: "14px",
+    lineHeight: "20px",
+    minHeight: "64px",
+    paddingBlock: "12px",
+  });
+  await expect.poll(readPreviewTimestampScale).toEqual(["12px", "18px"]);
+  await expect.poll(readSettingsChromeScale).toEqual(["24px", "14px", "18px"]);
+  await waitForAnimations(page);
+  await page.getByTestId("appearance-preferences-card").screenshot({
+    path: `${SHOTS}/16-conversation-density-spacious.png`,
+  });
+
+  await comfortable.click();
+  await expect(root).toHaveAttribute(
+    "data-conversation-density",
+    "comfortable",
+  );
+  await expect(comfortable).toHaveAttribute("aria-pressed", "true");
+
+  const controlBox = await control.boundingBox();
+  const compactBox = await compact.boundingBox();
+  const spaciousBox = await spacious.boundingBox();
+  expect(controlBox).not.toBeNull();
+  expect(compactBox).not.toBeNull();
+  expect(spaciousBox).not.toBeNull();
+  if (!controlBox || !compactBox || !spaciousBox) {
+    throw new Error("Conversation density control geometry is missing");
+  }
+  await page.mouse.move(
+    compactBox.x + compactBox.width / 2,
+    controlBox.y + controlBox.height / 2,
+  );
+  await page.mouse.down();
+  await page.mouse.move(
+    spaciousBox.x + spaciousBox.width / 2,
+    controlBox.y + controlBox.height / 2,
+  );
+  await expect(root).toHaveAttribute("data-conversation-density", "spacious");
+  await expect
+    .poll(() =>
+      page.evaluate(
+        (key) => window.localStorage.getItem(key),
+        CONVERSATION_DENSITY_STORAGE_KEY,
+      ),
+    )
+    .toBe("comfortable");
+  await expect
+    .poll(() =>
+      previewMessage.evaluate((element) => {
+        const style = window.getComputedStyle(element);
+        return [style.fontSize, style.lineHeight];
+      }),
+    )
+    .toEqual(["16px", "22px"]);
+  await expect.poll(readSettingsScale).toEqual({
+    fontSize: "14px",
+    lineHeight: "20px",
+    minHeight: "64px",
+    paddingBlock: "12px",
+  });
+  await page.mouse.up();
+  await expect(spacious).toHaveAttribute("aria-pressed", "true");
+  await expect
+    .poll(() =>
+      page.evaluate(
+        (key) => window.localStorage.getItem(key),
+        CONVERSATION_DENSITY_STORAGE_KEY,
+      ),
+    )
+    .toBe("spacious");
+  await comfortable.click();
+  await waitForAnimations(page);
+  await page.getByTestId("appearance-preferences-card").screenshot({
+    path: `${SHOTS}/14-conversation-density.png`,
+  });
+});
+
 test("appearance picker — system tab (Buzz follows OS)", async ({ page }) => {
   await seedTheme(page, "buzz");
   await installMockBridge(page);
@@ -1028,6 +1352,8 @@ test("glass background keeps the content panel solid", async ({ page }) => {
   const matchingRadiusControls = [
     page.getByTestId("appearance-color-mode-control"),
     page.getByTestId("appearance-color-mode-indicator"),
+    page.getByTestId("conversation-density-control"),
+    page.getByTestId("conversation-density-control-indicator"),
     page.getByTestId("theme-style-trigger"),
     page.getByTestId("link-preview-style-trigger"),
     page.getByTestId("thread-layout-trigger"),
diff --git a/desktop/tests/e2e/inbox-refactor-screenshots.spec.ts b/desktop/tests/e2e/inbox-refactor-screenshots.spec.ts
index 15a804d71..9a73d34e9 100644
--- a/desktop/tests/e2e/inbox-refactor-screenshots.spec.ts
+++ b/desktop/tests/e2e/inbox-refactor-screenshots.spec.ts
@@ -341,6 +341,9 @@ test.describe("inbox refactor screenshots", () => {
 
     const firstUnreadRow = page.getByTestId(`home-inbox-item-${replyIds[0]}`);
     await expect(firstUnreadRow).toBeVisible();
+    const listPreview = firstUnreadRow.locator(".inbox-preview-markdown");
+    await expect(listPreview).toHaveCSS("font-size", "15px");
+    await expect(listPreview).toHaveCSS("line-height", "20px");
     await firstUnreadRow.click();
 
     const detail = page.getByTestId("home-inbox-detail");
@@ -352,8 +355,137 @@ test.describe("inbox refactor screenshots", () => {
     await expect(page.getByTestId("home-inbox-selected-message")).toContainText(
       "Started on the changelog — first pass is up.",
     );
+
+    const selectedMessage = page.getByTestId("home-inbox-selected-message");
+    const selectedAuthor = selectedMessage.getByTestId("message-author");
+    const selectedBody = selectedMessage.locator(".message-markdown").first();
+    const selectedTimestamp = selectedMessage.getByTestId(
+      "inbox-message-timestamp",
+    );
+    const remainingListPreview = page
+      .locator("[data-testid^='home-inbox-item-']")
+      .locator(".inbox-preview-markdown")
+      .first();
+    const composerInput = page.getByTestId("message-input");
+    const readConversationMetrics = () =>
+      Promise.all([
+        remainingListPreview.evaluate((element) => {
+          const style = window.getComputedStyle(element);
+          return {
+            fontSize: style.fontSize,
+            lineHeight: style.lineHeight,
+          };
+        }),
+        selectedMessage.evaluate((element) => {
+          const style = window.getComputedStyle(element);
+          return {
+            paddingBottom: style.paddingBottom,
+            paddingTop: style.paddingTop,
+          };
+        }),
+        selectedAuthor.evaluate((element) => {
+          const style = window.getComputedStyle(element);
+          return {
+            fontSize: style.fontSize,
+            lineHeight: style.lineHeight,
+          };
+        }),
+        selectedBody.evaluate((element) => {
+          const style = window.getComputedStyle(element);
+          return {
+            fontSize: style.fontSize,
+            lineHeight: style.lineHeight,
+          };
+        }),
+        selectedTimestamp.evaluate((element) => {
+          const style = window.getComputedStyle(element);
+          return {
+            fontSize: style.fontSize,
+            lineHeight: style.lineHeight,
+          };
+        }),
+        composerInput.evaluate((element) => {
+          const style = window.getComputedStyle(element);
+          return {
+            fontSize: style.fontSize,
+            lineHeight: style.lineHeight,
+          };
+        }),
+      ]);
+    await expect.poll(readConversationMetrics).toEqual([
+      { fontSize: "15px", lineHeight: "20px" },
+      { paddingBottom: "6px", paddingTop: "6px" },
+      { fontSize: "15px", lineHeight: "17px" },
+      { fontSize: "15px", lineHeight: "20px" },
+      { fontSize: "11px", lineHeight: "16px" },
+      { fontSize: "15px", lineHeight: "20px" },
+    ]);
     await waitForAnimations(page);
 
     await page.screenshot({ path: `${SHOTS}/04-thread-context.png` });
+
+    await page.locator("html").evaluate((root) => {
+      root.setAttribute("data-conversation-density", "compact");
+    });
+    await expect.poll(readConversationMetrics).toEqual([
+      { fontSize: "14px", lineHeight: "19px" },
+      { paddingBottom: "4px", paddingTop: "4px" },
+      { fontSize: "14px", lineHeight: "16px" },
+      { fontSize: "14px", lineHeight: "19px" },
+      { fontSize: "10px", lineHeight: "14px" },
+      { fontSize: "14px", lineHeight: "19px" },
+    ]);
+    await waitForAnimations(page);
+    await page.screenshot({ path: `${SHOTS}/05-thread-context-compact.png` });
+
+    await page.locator("html").evaluate((root) => {
+      root.setAttribute("data-conversation-density", "spacious");
+    });
+    await expect.poll(readConversationMetrics).toEqual([
+      { fontSize: "16px", lineHeight: "22px" },
+      { paddingBottom: "8px", paddingTop: "8px" },
+      { fontSize: "16px", lineHeight: "18px" },
+      { fontSize: "16px", lineHeight: "22px" },
+      { fontSize: "12px", lineHeight: "18px" },
+      { fontSize: "16px", lineHeight: "22px" },
+    ]);
+    await waitForAnimations(page);
+    await page.screenshot({ path: `${SHOTS}/06-thread-context-spacious.png` });
+
+    await page.locator("html").evaluate((root) => {
+      root.setAttribute("data-conversation-density", "comfortable");
+    });
+
+    await page.evaluate(() => {
+      const isMac = /mac|iphone|ipad|ipod/i.test(navigator.platform);
+      window.dispatchEvent(
+        new KeyboardEvent("keydown", {
+          bubbles: true,
+          cancelable: true,
+          code: "Equal",
+          ctrlKey: !isMac,
+          key: "+",
+          metaKey: isMac,
+          shiftKey: true,
+        }),
+      );
+    });
+
+    await expect
+      .poll(async () => [
+        await page.evaluate(
+          () => window.getComputedStyle(document.documentElement).fontSize,
+        ),
+        ...(await readConversationMetrics()),
+      ])
+      .toEqual([
+        "17.6px",
+        { fontSize: "16.5px", lineHeight: "22px" },
+        { paddingBottom: "6.6px", paddingTop: "6.6px" },
+        { fontSize: "16.5px", lineHeight: "18.7px" },
+        { fontSize: "16.5px", lineHeight: "22px" },
+        { fontSize: "12.1px", lineHeight: "17.6px" },
+        { fontSize: "16.5px", lineHeight: "22px" },
+      ]);
   });
 });
diff --git a/desktop/tests/e2e/messaging.spec.ts b/desktop/tests/e2e/messaging.spec.ts
index adacdb629..4254b47c9 100644
--- a/desktop/tests/e2e/messaging.spec.ts
+++ b/desktop/tests/e2e/messaging.spec.ts
@@ -333,11 +333,11 @@ test("agent owner label identifies the agent and owner", async ({ page }) => {
     .filter({ hasText: "Hey team — checking in." });
   const ownerTreatment = aliceMessage.getByTestId("message-agent-owner");
 
-  await expect(ownerTreatment.locator("svg")).toBeVisible();
+  await expect(ownerTreatment.locator("svg")).toHaveCount(0);
   await expect(
     ownerTreatment.getByText("managed by", { exact: true }),
   ).toBeVisible();
-  await expect(ownerTreatment.locator(".font-semibold")).toHaveText("bob");
+  await expect(ownerTreatment.locator(".font-medium")).toHaveText("bob");
   await expect(ownerTreatment.getByRole("button")).toHaveAccessibleName("bob");
   await expect(ownerTreatment.locator(".sr-only")).toHaveText(
     "Agent managed by",