diff --git a/docs/profiles.md b/docs/profiles.md
index 0965bbc3..eb93d43a 100644
--- a/docs/profiles.md
+++ b/docs/profiles.md
@@ -3,7 +3,7 @@
 The bundled `buzz.profiles` plugin supplies a minimal, read-only panel for any
 public identity, human or agent. It uses the current session's shared profile
 directory. Agents retains agent-specific configuration/operations; this slice
-adds no ownership/running badge, editor, agent-library lookup or execution API.
+adds no ownership/running badge, editor, agent-library read or execution API.
 When Agent Activity is enabled and the host supplies conversation context, **View
 activity** opens its raw panel for this exact identity and originating channel.
 This action is offered for any public identity: it does not infer that the identity
@@ -45,11 +45,30 @@ Button use the host-loaded styles directly. The profile content marks its
 owns layout, not component overrides. No new theme owner, second global reset or
 shell migration. Designers own later refinement.
 
+Agent hints change avatar shape, not authority:
+
+- Profiles, mentions, participants and membership avatars use squircles for
+  self-declared `is_agent`/`isAgent` metadata or exact keys in the loaded session
+  library; otherwise they use circles. My Agents cards always use squircles.
+- Message authors also use these hints. An original kind-40002 envelope is enough
+  on its own and keeps that treatment through edits.
+- Library hints are lazy: opening or refreshing Agents loads them; clearing the
+  library removes that fallback. Avatars never fetch the library or scan telemetry.
+
+None of these hints proves ownership or running state. One bundled SVG mask scales
+across sizes and clips only artwork, leaving the profile button's focus ring intact.
+
 Use the normal `bin/just desktop` or `bin/just web` workflow in the feature worktree
 with the existing public live-mode pin; run only one dev target at a time.
 
 ## Evidence and remaining checks
 
+`avatar-shapes.spec.mjs` covers painted pixels and focus across sizes, themes and
+viewports in Chromium/WebKit, including the artwork inside participant/membership
+overlap borders (pictures and initials). Shape attributes alone do not prove that
+inset artwork is clipped. Completion tests cover loaded-library changes without
+another keystroke; profile-directory tests cover marker-only updates.
+
 `tests/browser/profiles.spec.mjs` runs real React/ChannelsPage, thread reading,
 profile directory, panel registry and plugin lifecycle against a synthetic
 transport. It covers avatar/mention keys, keyboard/focus, disable/re-enable,
diff --git a/src/bundled/agents/AgentsPage.tsx b/src/bundled/agents/AgentsPage.tsx
index e3cb0555..9c469499 100644
--- a/src/bundled/agents/AgentsPage.tsx
+++ b/src/bundled/agents/AgentsPage.tsx
@@ -196,7 +196,13 @@ function AgentCard({
   return (
     <article className="flex min-w-0 flex-col rounded-2xl border border-primary p-4">
       <div className="flex min-h-36 flex-1 items-center justify-center py-5">
-        <Avatar alt={name} fallback={name} src={picture ?? null} size="large" />
+        <Avatar
+          alt={name}
+          fallback={name}
+          src={picture ?? null}
+          size="large"
+          shape="squircle"
+        />
       </div>
       <h3 className="m-0 truncate text-label" title={name}>
         {name}
diff --git a/src/bundled/mentions/MentionCompletion.tsx b/src/bundled/mentions/MentionCompletion.tsx
index 9fbf7869..25dfe5bb 100644
--- a/src/bundled/mentions/MentionCompletion.tsx
+++ b/src/bundled/mentions/MentionCompletion.tsx
@@ -2,6 +2,7 @@ import { useEffect, useState, useSyncExternalStore } from "react";
 import type { ComposerCompletionProps } from "../../features/conversation/contracts";
 import type { RelaySession } from "../../features/relay/session";
 import { Avatar } from "../../shared/Avatar";
+import { useKnownAgentPubkeys } from "../../features/agents/use-known";
 import { matchesMentionQuery } from "./mention-query";
 
 // Demand bookkeeping only, not another profile cache. Missing names do not issue
@@ -23,6 +24,7 @@ export function MentionCompletion({
     session.profiles.snapshot,
     session.profiles.snapshot,
   );
+  const agentPubkeys = useKnownAgentPubkeys(session, profiles);
   const channel = list.channels.find((item) => item.id === channelId);
   const members = channel?.members ?? [];
   const memberKey = members.join(":");
@@ -85,6 +87,7 @@ export function MentionCompletion({
               "small",
             )}
             className="size-7 rounded-lg text-caption"
+            shape={agentPubkeys.has(recipient.pubkey) ? "squircle" : "circle"}
           />
         ),
         edit: { mention: recipient },
@@ -140,6 +143,7 @@ export function MentionCompletion({
     channelId,
     memberKey,
     profiles,
+    agentPubkeys,
     query.query,
     publish,
     error,
diff --git a/src/bundled/mentions/MentionPicker.tsx b/src/bundled/mentions/MentionPicker.tsx
index b2f17a79..8e013fc9 100644
--- a/src/bundled/mentions/MentionPicker.tsx
+++ b/src/bundled/mentions/MentionPicker.tsx
@@ -1,4 +1,5 @@
 import { Avatar } from "../../shared/Avatar";
+import { useKnownAgentPubkeys } from "../../features/agents/use-known";
 import { AtSign } from "lucide-react";
 import {
   useEffect,
@@ -39,6 +40,7 @@ export function MentionPicker({
     session.profiles.snapshot,
     session.profiles.snapshot,
   );
+  const agentPubkeys = useKnownAgentPubkeys(session, profiles);
   const channel = list.channels.find((item) => item.id === channelId);
   const memberKey = channel?.members?.join(":") ?? "";
   useEffect(() => {
@@ -141,6 +143,9 @@ export function MentionPicker({
                     "small",
                   )}
                   className="size-8 rounded-lg text-caption"
+                  shape={
+                    agentPubkeys.has(recipient.pubkey) ? "squircle" : "circle"
+                  }
                 />
                 <span className={styles.mentionLabel}>
                   <span>{recipient.name}</span>
diff --git a/src/bundled/profiles/ProfilePanel.tsx b/src/bundled/profiles/ProfilePanel.tsx
index b0e4e260..debfcb0c 100644
--- a/src/bundled/profiles/ProfilePanel.tsx
+++ b/src/bundled/profiles/ProfilePanel.tsx
@@ -7,6 +7,7 @@ import {
 } from "react";
 import { IconCopy } from "@tabler/icons-react";
 import { Avatar } from "../../shared/design-system/ui/Avatar";
+import { useKnownAgentPubkeys } from "../../features/agents/use-known";
 import { Button } from "../../shared/design-system/ui/Button";
 import { activityTarget } from "../../features/agents/activity-target";
 import type { PanelProps } from "../../features/panels/service";
@@ -49,11 +50,12 @@ function ProfileDetails({
     () => selectProfiles(session.profiles, [pubkey]),
     [session.profiles, pubkey],
   );
-  const profile = useSyncExternalStore(
+  const profiles = useSyncExternalStore(
     selection.subscribe,
     selection.snapshot,
     selection.snapshot,
-  ).get(pubkey);
+  );
+  const profile = profiles.get(pubkey);
   const [status, setStatus] = useState<"loading" | "ready" | "error">(
     "loading",
   );
@@ -80,6 +82,7 @@ function ProfileDetails({
       active = false;
     };
   }, [session, pubkey, attempt]);
+  const agentPubkeys = useKnownAgentPubkeys(session, profiles);
   const npub = profileTarget(pubkey)?.slice(6) ?? pubkey;
   const name = profile?.name ?? "Unknown profile";
   const activity = activityTarget(pubkey, context?.channelId);
@@ -103,6 +106,7 @@ function ProfileDetails({
             alt={`${name} avatar`}
             fallback={profile?.name ?? "?"}
             size={picture ? "fill" : "large"}
+            shape={agentPubkeys.has(pubkey) ? "squircle" : "circle"}
           />
         </div>
         <h2 className="text-heading">{name}</h2>
diff --git a/src/features/agents/known.test.ts b/src/features/agents/known.test.ts
new file mode 100644
index 00000000..11a6e636
--- /dev/null
+++ b/src/features/agents/known.test.ts
@@ -0,0 +1,14 @@
+import { expect, it } from "vitest";
+import { knownAgentPubkeys } from "./known";
+
+it("combines exact local-library identities with self-authored agent profiles", () => {
+  const profiles = new Map([
+    ["relay-agent", { name: "Relay", isAgent: true as const }],
+    ["person", { name: "Person" }],
+  ]);
+  const keys = knownAgentPubkeys(profiles, {
+    definitions: [],
+    identities: [{ pubkey: "local-agent", name: "Local" }],
+  });
+  expect([...keys]).toEqual(["relay-agent", "local-agent"]);
+});
diff --git a/src/features/agents/known.ts b/src/features/agents/known.ts
new file mode 100644
index 00000000..68e9664f
--- /dev/null
+++ b/src/features/agents/known.ts
@@ -0,0 +1,16 @@
+import type { AgentLibrary } from "./library";
+import type { Profile } from "../relay/contracts";
+
+/** Exact keys from self-declared profile hints plus the local Buzz library.
+ * Display-only evidence, not proof of ownership, membership or authority. */
+export function knownAgentPubkeys(
+  profiles: ReadonlyMap<string, Profile>,
+  library?: AgentLibrary,
+): ReadonlySet<string> {
+  const keys = new Set<string>();
+  for (const [pubkey, profile] of profiles) {
+    if (profile.isAgent) keys.add(pubkey);
+  }
+  for (const identity of library?.identities ?? []) keys.add(identity.pubkey);
+  return keys;
+}
diff --git a/src/features/agents/use-known.ts b/src/features/agents/use-known.ts
new file mode 100644
index 00000000..e5ec7bc4
--- /dev/null
+++ b/src/features/agents/use-known.ts
@@ -0,0 +1,21 @@
+import { useMemo, useSyncExternalStore } from "react";
+import type { Profile } from "../relay/contracts";
+import type { RelaySession } from "../relay/session";
+import { knownAgentPubkeys } from "./known";
+
+/** One display-only projection per owning surface; exact keys, never display names.
+ * Subscribes to existing evidence without initiating library reads. */
+export function useKnownAgentPubkeys(
+  session: RelaySession,
+  profiles: ReadonlyMap<string, Profile>,
+): ReadonlySet<string> {
+  const library = useSyncExternalStore(
+    session.agentLibrary.subscribe,
+    session.agentLibrary.snapshot,
+    session.agentLibrary.snapshot,
+  );
+  return useMemo(
+    () => knownAgentPubkeys(profiles, library),
+    [profiles, library],
+  );
+}
diff --git a/src/features/messages/ChannelTimeline.test.tsx b/src/features/messages/ChannelTimeline.test.tsx
index db09202f..8616432c 100644
--- a/src/features/messages/ChannelTimeline.test.tsx
+++ b/src/features/messages/ChannelTimeline.test.tsx
@@ -3,6 +3,7 @@ import { afterEach, expect, it, vi } from "vitest";
 import type { ReactElement } from "react";
 import { Virtualizer } from "virtua";
 import { ChannelTimeline } from "./ChannelTimeline";
+import { createAgentLibrary } from "../agents/library";
 import { createRelaySession } from "../relay/session";
 import {
   bounds,
@@ -91,6 +92,8 @@ vi.mock("react", async (original) => ({
       });
     }
   },
+  useSyncExternalStore: (_subscribe: unknown, snapshot: () => unknown) =>
+    snapshot(),
 }));
 vi.mock("../relay/react", () => ({
   useRowProfiles: () => new Map(),
@@ -230,6 +233,7 @@ function setup({
     ({
       channels: { loadOlder, window: snapshot },
       profiles: {},
+      agentLibrary: createAgentLibrary(undefined).queries,
       // Geometry fixtures are read-only; reading behavior has its own boundary tests.
       unread: { sync: () => ({ capability: "unsupported" }) },
       media: () => undefined,
diff --git a/src/features/messages/ChannelTimeline.tsx b/src/features/messages/ChannelTimeline.tsx
index 464b441b..8a210217 100644
--- a/src/features/messages/ChannelTimeline.tsx
+++ b/src/features/messages/ChannelTimeline.tsx
@@ -15,6 +15,7 @@ import { useReading } from "./use-reading";
 import { useMessageReveal } from "./use-message-reveal";
 import type { PageNavigation } from "../navigation/service";
 import { messageViewKey } from "./view-key";
+import { useKnownAgentPubkeys } from "../agents/use-known";
 
 const EDGE_HEIGHT = 56;
 type ReadingPosition = {
@@ -107,6 +108,7 @@ function Timeline({
   const restoredAnchor = useRef<string | undefined>(undefined);
   const rows = useMemo(() => membershipRows(window.rows), [window.rows]);
   const profiles = useRowProfiles(queries.profiles, window.rows);
+  const agentPubkeys = useKnownAgentPubkeys(queries, profiles);
   const geometry = useMemo(() => geometryFor(queries.channels), [queries]);
   const signature = useMemo(
     () => geometrySignature(window.rows, profiles),
@@ -481,6 +483,7 @@ function Timeline({
                 profiles={profiles}
                 viewer={viewer}
                 media={queries.media}
+                agentPubkeys={agentPubkeys}
                 day={day}
               />
             ) : (
@@ -493,6 +496,7 @@ function Timeline({
                 extensions={extensions}
                 profile={profiles.get(row.authorId)}
                 participantProfiles={profiles}
+                agentPubkeys={agentPubkeys}
                 media={queries.media}
                 onOpenLink={onOpenLink}
                 canOpenLink={canOpenLink}
diff --git a/src/features/messages/MembershipRow.tsx b/src/features/messages/MembershipRow.tsx
index d4b0609d..f378099a 100644
--- a/src/features/messages/MembershipRow.tsx
+++ b/src/features/messages/MembershipRow.tsx
@@ -1,3 +1,4 @@
+import "../../shared/design-system/styles/avatar-shape.css";
 import { memo } from "react";
 import type { Profile } from "../relay/contracts";
 import { membershipDescription, type TimelineRow } from "./membership-rows";
@@ -9,12 +10,14 @@ export const MembershipRow = memo(function MembershipRow({
   profiles,
   viewer,
   media,
+  agentPubkeys,
   day,
 }: {
   row: TimelineRow;
   profiles: ReadonlyMap<string, Profile>;
   viewer?: string | undefined;
   media(url: string, size?: "small"): string | undefined;
+  agentPubkeys?: ReadonlySet<string> | undefined;
   day: boolean;
 }) {
   const { targets, text, title } = membershipDescription(
@@ -44,25 +47,38 @@ export const MembershipRow = memo(function MembershipRow({
               ? media(profile.picture, "small")
               : undefined;
             return (
-              <span className={styles.membershipAvatar} key={id}>
-                {name.slice(0, 2).toUpperCase()}
-                {picture && (
-                  <img
-                    key={picture}
-                    src={picture}
-                    alt=""
-                    loading="lazy"
-                    onError={(event) => {
-                      event.currentTarget.hidden = true;
-                    }}
-                  />
-                )}
+              <span
+                className={styles.membershipAvatar}
+                data-avatar-shape={
+                  agentPubkeys?.has(id) ? "squircle" : "circle"
+                }
+                key={id}
+              >
+                <span className={styles.insetAvatarArtwork}>
+                  {name.slice(0, 2).toUpperCase()}
+                  {picture && (
+                    <img
+                      key={picture}
+                      src={picture}
+                      alt=""
+                      loading="lazy"
+                      onError={(event) => {
+                        event.currentTarget.hidden = true;
+                      }}
+                    />
+                  )}
+                </span>
               </span>
             );
           })}
           {targets.length > 3 && (
-            <span className={styles.membershipAvatar}>
-              +{targets.length - 3}
+            <span
+              className={styles.membershipAvatar}
+              data-avatar-shape="circle"
+            >
+              <span className={styles.insetAvatarArtwork}>
+                +{targets.length - 3}
+              </span>
             </span>
           )}
         </span>
diff --git a/src/features/messages/MessageRow.test.tsx b/src/features/messages/MessageRow.test.tsx
index 224d9ffd..0adf2988 100644
--- a/src/features/messages/MessageRow.test.tsx
+++ b/src/features/messages/MessageRow.test.tsx
@@ -376,6 +376,55 @@ it("does not bypass the session media resolver to paint an inaccessible attachme
   expect(html).not.toContain("<img");
 });
 
+it("uses the reviewed SVG squircle only for identities classified as agents", () => {
+  const agent = "a".repeat(64);
+  const media = vi.fn((url: string) => url);
+  const html = renderToStaticMarkup(
+    <MessageRow
+      row={{ ...row, authorId: agent }}
+      profile={{ name: "Carl", picture: "https://image.test/agent.png" }}
+      agentPubkeys={new Set([agent])}
+      media={media}
+      onOpenLink={() => false}
+      day={false}
+      retry={undefined}
+    />,
+  );
+  expect(html).toContain('data-avatar-shape="squircle"');
+  expect(media).toHaveBeenCalledWith("https://image.test/agent.png", "small");
+  expect(render({}, 0).html).toContain('data-avatar-shape="circle"');
+});
+
+it.each([9, 40002])(
+  "renders kind %s author shape from the existing fold without profile/library evidence",
+  (kind) => {
+    const author = keypair(),
+      relay = keypair();
+    const [folded] = foldMessages("channel", relay.pubkey, [
+      signed(author, {
+        kind,
+        content:
+          kind === 40002 ? JSON.stringify({ content: "Reply" }) : "Reply",
+        tags: [["h", "channel"]],
+      }),
+    ]);
+    if (!folded) throw new Error("Missing row");
+    const html = renderToStaticMarkup(
+      <MessageRow
+        row={folded}
+        profile={undefined}
+        media={() => undefined}
+        onOpenLink={() => false}
+        day={false}
+        retry={undefined}
+      />,
+    );
+    expect(html).toContain(
+      `data-avatar-shape="${kind === 40002 ? "squircle" : "circle"}"`,
+    );
+  },
+);
+
 it("requests a small profile image without downsizing message attachments", () => {
   const media = vi.fn((url: string) => url);
   renderToStaticMarkup(
diff --git a/src/features/messages/MessageRow.tsx b/src/features/messages/MessageRow.tsx
index f112d9e0..30c02295 100644
--- a/src/features/messages/MessageRow.tsx
+++ b/src/features/messages/MessageRow.tsx
@@ -29,6 +29,7 @@ export type MessageRowProps = {
   extensions?: ConversationExtensions | undefined;
   profile: Profile | undefined;
   participantProfiles?: ReadonlyMap<string, Profile> | undefined;
+  agentPubkeys?: ReadonlySet<string> | undefined;
   canOpenLink?: ((target: string) => boolean) | undefined;
   media(url: string, size?: "small"): string | undefined;
   onOpenLink(url: string): boolean;
@@ -53,6 +54,7 @@ export const MessageRow = memo(function MessageRow({
   retry,
   onOpenThread,
   participantProfiles,
+  agentPubkeys,
 }: MessageRowProps) {
   const directory = useReferenceDirectory(session, row.mentions.length > 0);
   const threadUnread = useThreadUnread(
@@ -104,7 +106,7 @@ export const MessageRow = memo(function MessageRow({
       )}
       <div className={styles.message}>
         <AvatarTag
-          className={styles.avatar}
+          className={styles.avatarButton}
           {...(clickable
             ? {
                 type: "button" as const,
@@ -116,11 +118,20 @@ export const MessageRow = memo(function MessageRow({
               }
             : {})}
         >
-          {picture ? (
-            <img src={picture} alt="" loading="lazy" />
-          ) : (
-            name.slice(0, 2).toUpperCase()
-          )}
+          <span
+            className={styles.avatar}
+            data-avatar-shape={
+              row.agentEnvelope || agentPubkeys?.has(row.authorId)
+                ? "squircle"
+                : "circle"
+            }
+          >
+            {picture ? (
+              <img src={picture} alt="" loading="lazy" />
+            ) : (
+              name.slice(0, 2).toUpperCase()
+            )}
+          </span>
         </AvatarTag>
         <div className={styles.messageBody}>
           <div className={styles.byline}>
@@ -224,26 +235,36 @@ export const MessageRow = memo(function MessageRow({
                       <span
                         key={id}
                         className={styles.threadAvatar}
+                        data-avatar-shape={
+                          agentPubkeys?.has(id) ? "squircle" : "circle"
+                        }
                         title={name}
                       >
-                        {name.slice(0, 2).toUpperCase()}
-                        {picture && (
-                          <img
-                            key={picture}
-                            src={picture}
-                            alt=""
-                            loading="lazy"
-                            onError={(event) => {
-                              event.currentTarget.hidden = true;
-                            }}
-                          />
-                        )}
+                        <span className={styles.insetAvatarArtwork}>
+                          {name.slice(0, 2).toUpperCase()}
+                          {picture && (
+                            <img
+                              key={picture}
+                              src={picture}
+                              alt=""
+                              loading="lazy"
+                              onError={(event) => {
+                                event.currentTarget.hidden = true;
+                              }}
+                            />
+                          )}
+                        </span>
                       </span>
                     );
                   })}
                   {row.participants.length > 3 && (
-                    <span className={styles.threadAvatar}>
-                      +{row.participants.length - 3}
+                    <span
+                      className={styles.threadAvatar}
+                      data-avatar-shape="circle"
+                    >
+                      <span className={styles.insetAvatarArtwork}>
+                        +{row.participants.length - 3}
+                      </span>
                     </span>
                   )}
                 </span>
diff --git a/src/features/messages/Messages.module.css b/src/features/messages/Messages.module.css
index 373070e2..c52d2033 100644
--- a/src/features/messages/Messages.module.css
+++ b/src/features/messages/Messages.module.css
@@ -1,3 +1,5 @@
+@import "../../shared/design-system/styles/avatar-shape.css";
+
 /* Reusable conversation components; plugins own placement and surrounding layout. */
 .thread {
   min-width: 0;
@@ -66,11 +68,20 @@
   gap: var(--space-4);
   padding: var(--space-2) 0 var(--space-section-gap);
 }
+.avatarButton {
+  flex-shrink: 0;
+  align-self: flex-start;
+  border-radius: var(--radius-sm);
+}
+html[data-keyboard-navigation] button.avatarButton:focus-visible {
+  outline: 2px solid var(--focus);
+  outline-offset: 2px;
+}
+
 .avatar {
   width: 40px;
   height: 40px;
   flex-shrink: 0;
-  border-radius: 50%;
   background: var(--surface-accent);
   color: var(--text-muted);
   display: grid;
@@ -388,8 +399,7 @@
   margin-right: calc(-1 * var(--space-half));
   overflow: hidden;
   border: 2px solid var(--surface);
-  border-radius: 50%;
-  background: var(--surface-accent);
+  background: var(--surface);
   color: var(--text-muted);
   font-size: var(--text-caption);
   line-height: var(--text-caption--line-height);
@@ -585,12 +595,14 @@
   font-style: italic;
 }
 
-button.avatar {
+button.avatarButton {
   padding: 0;
   border: 0;
+  background: transparent;
   cursor: pointer;
 }
-button.avatar:hover {
+button.avatarButton:hover {
+  background: transparent;
   box-shadow: 0 0 0 2px var(--border);
 }
 .mention {
@@ -607,7 +619,6 @@ button.avatar:hover {
 .mention:hover {
   text-decoration: underline;
 }
-button.avatar:focus-visible,
 .mention:focus-visible {
   outline: 2px solid var(--focus);
   outline-offset: 2px;
@@ -642,9 +653,8 @@ button.avatar:focus-visible,
   height: 28px;
   margin-right: calc(-1 * var(--space-1h));
   border: 2px solid var(--surface);
-  border-radius: var(--radius-row);
   overflow: hidden;
-  background: var(--surface-accent);
+  background: var(--surface);
   color: var(--text-muted);
   font-size: var(--text-caption);
   line-height: var(--text-caption--line-height);
@@ -658,6 +668,19 @@ button.avatar:focus-visible,
   object-fit: cover;
 }
 
+/* The overlap border and its inset artwork need independently scaled curves. */
+.insetAvatarArtwork {
+  position: relative;
+  display: grid;
+  place-items: center;
+  width: 100%;
+  height: 100%;
+  overflow: hidden;
+  background: var(--surface-accent);
+  border-radius: inherit;
+  mask: inherit;
+}
+
 .typing {
   color: var(--text-muted);
   font-size: var(--text-caption);
diff --git a/src/features/messages/ThreadPanel.test.tsx b/src/features/messages/ThreadPanel.test.tsx
index 0d44b018..3d5294d7 100644
--- a/src/features/messages/ThreadPanel.test.tsx
+++ b/src/features/messages/ThreadPanel.test.tsx
@@ -10,6 +10,7 @@ import {
   type ReactNode,
 } from "react";
 import { ThreadPanel } from "./ThreadPanel";
+import { createAgentLibrary } from "../agents/library";
 import { MessageRow } from "./MessageRow";
 import { MessageMarkdown } from "./MessageMarkdown";
 import { MessageComposer } from "./MessageComposer";
@@ -148,6 +149,7 @@ function setup() {
   const session = {
     thread,
     profiles: { ensure },
+    agentLibrary: createAgentLibrary(undefined).queries,
     messages: { retry: vi.fn() },
     // Geometry fixtures are read-only; reading behavior has its own boundary tests.
     unread: { sync: () => ({ capability: "unsupported" }) },
diff --git a/src/features/messages/ThreadPanel.tsx b/src/features/messages/ThreadPanel.tsx
index df639a23..38ba6c7b 100644
--- a/src/features/messages/ThreadPanel.tsx
+++ b/src/features/messages/ThreadPanel.tsx
@@ -22,6 +22,7 @@ import { useReading } from "./use-reading";
 import { useMessageReveal } from "./use-message-reveal";
 import type { PageNavigation } from "../navigation/service";
 import { messageViewKey } from "./view-key";
+import { useKnownAgentPubkeys } from "../agents/use-known";
 
 export type ThreadPanelProps = {
   extensions?: ConversationExtensions | undefined;
@@ -196,6 +197,7 @@ function ThreadMessages({
         .catch(() => {});
   }, [session.profiles, authors]);
   const profiles = useRowProfiles(session.profiles, rows);
+  const agentPubkeys = useKnownAgentPubkeys(session, profiles);
   const scroller = useRef<HTMLElement>(null);
   const positioned = useRef(false);
   const follow = useRef(true);
@@ -329,6 +331,7 @@ function ThreadMessages({
             row={snapshot.root}
             profile={profiles.get(snapshot.root.authorId)}
             participantProfiles={profiles}
+            agentPubkeys={agentPubkeys}
             media={session.media}
             onOpenLink={onOpenLink}
             canOpenLink={canOpenLink}
@@ -354,6 +357,7 @@ function ThreadMessages({
                 row={row}
                 profile={profiles.get(row.authorId)}
                 participantProfiles={profiles}
+                agentPubkeys={agentPubkeys}
                 media={session.media}
                 onOpenLink={onOpenLink}
                 canOpenLink={canOpenLink}
diff --git a/src/features/messages/membership-rows.test.tsx b/src/features/messages/membership-rows.test.tsx
index e313bb82..a6fd7a8e 100644
--- a/src/features/messages/membership-rows.test.tsx
+++ b/src/features/messages/membership-rows.test.tsx
@@ -1,4 +1,4 @@
-import { assert, expect, it } from "vitest";
+import { assert, expect, it, vi } from "vitest";
 import { renderToStaticMarkup } from "react-dom/server";
 import type { ChannelMessage, MembershipChange } from "../relay/contracts";
 import { membershipRows, membershipDescription } from "./membership-rows";
@@ -181,6 +181,28 @@ it("caps visible names/avatars with an overflow count, retaining all names in th
   expect(html).toContain("data-membership-row");
   expect(html).toContain("dddddddddd");
 });
+it.each([false, true])(
+  "keeps small membership media requests with agent hint %s",
+  (agent) => {
+    const picture = "https://image.test/member.png";
+    const media = vi.fn((url: string) => url);
+    const html = renderToStaticMarkup(
+      <MembershipRow
+        row={row("join", joined(pinky, pinky))}
+        profiles={new Map([[pinky, { name: "Pinky", picture }]])}
+        agentPubkeys={new Set(agent ? [pinky] : [])}
+        media={media}
+        day={false}
+      />,
+    );
+    expect(media).toHaveBeenCalledWith(picture, "small");
+    expect(html).toContain(
+      `data-avatar-shape="${agent ? "squircle" : "circle"}"`,
+    );
+    expect(html).toContain('aria-hidden="true"');
+    expect(html).not.toContain("button");
+  },
+);
 it("actor/subject profile enrichment invalidates cached system-row geometry", () => {
   const rows = [row("a", joined(wes, pinky))];
   const original = geometrySignature(rows, profiles);
diff --git a/src/features/relay/contracts.ts b/src/features/relay/contracts.ts
index 7477f82c..3ab660c6 100644
--- a/src/features/relay/contracts.ts
+++ b/src/features/relay/contracts.ts
@@ -19,6 +19,8 @@ export type Profile = Readonly<{
   name: string;
   picture?: string;
   about?: string;
+  /** Self-declared display hint, not proof of ownership, membership or authority. */
+  isAgent?: true;
 }>;
 export type Attachment = Readonly<{
   url: string;
@@ -42,6 +44,8 @@ export type ChannelMessage = Readonly<{
   /** Unix seconds from the signed event. Ordering is (createdAt asc, id desc); no clock inference. */
   createdAt: number;
   content: string;
+  /** Original kind 40002, regardless of edits; self-declared display evidence, not authority. */
+  agentEnvelope?: true;
   membership?: MembershipChange;
   /** Current body came from a replacement edit; original recipients do not bind its prose. */
   edited?: true;
diff --git a/src/features/relay/fold.test.ts b/src/features/relay/fold.test.ts
index fe77b4bd..480997f8 100644
--- a/src/features/relay/fold.test.ts
+++ b/src/features/relay/fold.test.ts
@@ -194,6 +194,46 @@ describe("message fold", () => {
     },
   );
 
+  it.each([
+    [9, "Plain message"],
+    [9, JSON.stringify({ content: "Envelope-looking prose", is_agent: true })],
+    [40002, JSON.stringify({ content: "Agent message" })],
+    [40002, "Malformed envelope"],
+  ])(
+    "keeps the original kind %s display hint independent of body and edits (%s)",
+    (kind, content) => {
+      const original = signed(alice, {
+        kind,
+        content,
+        created_at: 10,
+        tags: [["h", channel]],
+      });
+      const hint = kind === 40002 ? true : undefined;
+      expect(
+        foldMessages(channel, relay.pubkey, [original])[0]?.agentEnvelope,
+      ).toBe(hint);
+      for (const replacement of [
+        "Plain edit",
+        JSON.stringify({ content: "Envelope edit" }),
+      ]) {
+        const edit = signed(alice, {
+          kind: 40003,
+          content: replacement,
+          created_at: 11,
+          tags: [["e", original.id]],
+        });
+        const [row] = foldMessages(channel, relay.pubkey, [original, edit]);
+        expect(row?.edited).toBe(true);
+        expect(row?.agentEnvelope).toBe(hint);
+        expect(row?.content).toBe(
+          kind === 40002 && replacement.startsWith("{")
+            ? "Envelope edit"
+            : replacement,
+        );
+      }
+    },
+  );
+
   it("unwraps agent envelopes and projects valid CommonMark images through one safe URL policy", () => {
     const agent = signed(bob, {
       kind: 40002,
diff --git a/src/features/relay/fold.ts b/src/features/relay/fold.ts
index b404f69d..abc298ef 100644
--- a/src/features/relay/fold.ts
+++ b/src/features/relay/fold.ts
@@ -165,6 +165,7 @@ export function foldMessages(
         authorId: event.pubkey,
         createdAt: event.created_at,
         content: projected.content,
+        ...(event.kind === 40002 ? { agentEnvelope: true as const } : {}),
         ...(edits.length ? { edited: true as const } : {}),
         ...(projected.content !== content &&
         projected.content !== content.trimEnd()
diff --git a/src/features/relay/profile-details.test.ts b/src/features/relay/profile-details.test.ts
index d1919044..9bc8b1e6 100644
--- a/src/features/relay/profile-details.test.ts
+++ b/src/features/relay/profile-details.test.ts
@@ -1,8 +1,9 @@
-import { expect, it } from "vitest";
+import { expect, it, vi } from "vitest";
+import { selectProfiles } from "./profile-selection";
 import { foldProfiles } from "./profiles";
 import { createProfileDirectory } from "./profile-directory";
 import { createRelayReader } from "./reader";
-import { keypair, profile, scriptedTransport } from "./testing";
+import { keypair, profile, scriptedTransport, signed } from "./testing";
 const user = keypair();
 it("projects about safely and publishes an about-only replacement/removal", () => {
   const wire = scriptedTransport(user.pubkey, keypair().pubkey);
@@ -29,3 +30,69 @@ it("projects about safely and publishes an about-only replacement/removal", () =
     reader.dispose();
   }
 });
+
+it("retains self-authored agent metadata without inferring it from display names", () => {
+  const author = keypair();
+  const profiles = foldProfiles([
+    signed(author, {
+      kind: 0,
+      content: JSON.stringify({ name: "Agent-looking human", is_agent: true }),
+      tags: [],
+    }),
+  ]);
+  expect(profiles.get(author.pubkey)?.isAgent).toBe(true);
+});
+
+it.each([
+  { field: "is_agent", removal: { is_agent: false } },
+  { field: "isAgent", removal: {} },
+])(
+  "notifies the directory and selected profile on $field-only addition/removal",
+  ({ field, removal }) => {
+    const wire = scriptedTransport(user.pubkey, keypair().pubkey);
+    const reader = createRelayReader(wire.transport);
+    const directory = createProfileDirectory(reader.reader);
+    const selection = selectProfiles(directory.queries, [user.pubkey]);
+    const directoryChanged = vi.fn();
+    const selectedChanged = vi.fn();
+    const unsubscribeDirectory = directory.queries.subscribe(directoryChanged);
+    const unsubscribeSelection = selection.subscribe(selectedChanged);
+    try {
+      directory.accept([profile(user, { name: "Mic" }, 1)]);
+      const before = selection.snapshot();
+      directoryChanged.mockClear();
+      selectedChanged.mockClear();
+
+      directory.accept([profile(user, { name: "Mic", [field]: true }, 2)]);
+      const added = selection.snapshot();
+      expect(added).not.toBe(before);
+      expect(added.get(user.pubkey)).toBe(
+        directory.queries.snapshot().get(user.pubkey),
+      );
+      expect(added.get(user.pubkey)).toEqual({ name: "Mic", isAgent: true });
+      expect(directoryChanged).toHaveBeenCalledTimes(1);
+      expect(selectedChanged).toHaveBeenCalledTimes(1);
+
+      // A newer event with identical display values must still preserve identity.
+      directory.accept([profile(user, { name: "Mic", [field]: true }, 3)]);
+      expect(selection.snapshot()).toBe(added);
+      expect(directoryChanged).toHaveBeenCalledTimes(1);
+      expect(selectedChanged).toHaveBeenCalledTimes(1);
+
+      directory.accept([profile(user, { name: "Mic", ...removal }, 4)]);
+      const removed = selection.snapshot();
+      expect(removed).not.toBe(added);
+      expect(removed.get(user.pubkey)).toBe(
+        directory.queries.snapshot().get(user.pubkey),
+      );
+      expect(removed.get(user.pubkey)).toEqual({ name: "Mic" });
+      expect(directoryChanged).toHaveBeenCalledTimes(2);
+      expect(selectedChanged).toHaveBeenCalledTimes(2);
+    } finally {
+      unsubscribeSelection();
+      unsubscribeDirectory();
+      directory.dispose();
+      reader.dispose();
+    }
+  },
+);
diff --git a/src/features/relay/profile-directory.ts b/src/features/relay/profile-directory.ts
index a3c895ee..731de677 100644
--- a/src/features/relay/profile-directory.ts
+++ b/src/features/relay/profile-directory.ts
@@ -54,7 +54,8 @@ export function createProfileDirectory(
       if (
         old?.name === value.name &&
         old?.picture === value.picture &&
-        old?.about === value.about
+        old?.about === value.about &&
+        old?.isAgent === value.isAgent
       )
         next.set(id, old);
     }
diff --git a/src/features/relay/profiles.ts b/src/features/relay/profiles.ts
index 85909795..43cfa589 100644
--- a/src/features/relay/profiles.ts
+++ b/src/features/relay/profiles.ts
@@ -20,6 +20,8 @@ export function foldProfiles(
         name?: unknown;
         picture?: unknown;
         about?: unknown;
+        is_agent?: unknown;
+        isAgent?: unknown;
       };
       const name = [body.display_name, body.name].find(
         (value): value is string =>
@@ -37,6 +39,9 @@ export function foldProfiles(
           ...(typeof body.about === "string" && body.about.trim()
             ? { about: body.about.trim() }
             : {}),
+          ...(body.is_agent === true || body.isAgent === true
+            ? { isAgent: true as const }
+            : {}),
         }),
       );
     } catch {
diff --git a/src/shared/Avatar.tsx b/src/shared/Avatar.tsx
index 291376e7..97d115f4 100644
--- a/src/shared/Avatar.tsx
+++ b/src/shared/Avatar.tsx
@@ -1,3 +1,4 @@
+import "./design-system/styles/avatar-shape.css";
 import { useState } from "react";
 
 /** Caller resolves private relay media through the current session. */
@@ -5,10 +6,12 @@ export function Avatar({
   name,
   src,
   className = "",
+  shape = "circle",
 }: {
   name: string;
   src?: string | undefined;
   className?: string;
+  shape?: "circle" | "squircle";
 }) {
   const [failed, setFailed] = useState<string>();
   const initials =
@@ -21,6 +24,7 @@ export function Avatar({
       .toUpperCase() || "?";
   return (
     <span
+      data-avatar-shape={shape}
       className={`relative inline-grid shrink-0 place-items-center overflow-hidden rounded-2xl bg-neutral-3 font-semibold text-secondary ${className}`}
       aria-hidden="true"
     >
diff --git a/src/shared/design-system/styles/avatar-shape.css b/src/shared/design-system/styles/avatar-shape.css
new file mode 100644
index 00000000..b4caa7e4
--- /dev/null
+++ b/src/shared/design-system/styles/avatar-shape.css
@@ -0,0 +1,12 @@
+/* Shared by system and legacy avatars. The SVG viewBox scales the same curve
+   at every size; CSS path() coordinates would be fixed pixels. Apply only to
+   artwork, never its interactive wrapper, so focus and hover remain unclipped.
+   Unlayered to replace legacy utility/module radii as well as system defaults. */
+[data-avatar-shape="circle"] {
+  border-radius: 50%;
+}
+
+[data-avatar-shape="squircle"] {
+  border-radius: 0;
+  mask: url("./avatar-squircle.svg") center / 100% 100% no-repeat;
+}
diff --git a/src/shared/design-system/styles/avatar-squircle.svg b/src/shared/design-system/styles/avatar-squircle.svg
new file mode 100644
index 00000000..f7806eb4
--- /dev/null
+++ b/src/shared/design-system/styles/avatar-squircle.svg
@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 1 1"><title>Squircle avatar mask</title><path d="M .5 0 C .93 0 1 .07 1 .5 C 1 .93 .93 1 .5 1 C .07 1 0 .93 0 .5 C 0 .07 .07 0 .5 0 Z"/></svg>
diff --git a/src/shared/design-system/ui/Avatar.tsx b/src/shared/design-system/ui/Avatar.tsx
index 8c11c13e..3d567be9 100644
--- a/src/shared/design-system/ui/Avatar.tsx
+++ b/src/shared/design-system/ui/Avatar.tsx
@@ -1,3 +1,4 @@
+import "../styles/avatar-shape.css";
 import { Avatar as BaseAvatar } from "@base-ui/react/avatar";
 import { useEffect, useState } from "react";
 
@@ -36,11 +37,13 @@ export function Avatar({
   alt,
   fallback,
   size = "default",
+  shape = "circle",
 }: {
   src?: string | null;
   alt: string;
   fallback: string;
   size?: AvatarSize;
+  shape?: "circle" | "squircle";
 }) {
   const initial = fallback.slice(0, 1).toUpperCase();
   return (
@@ -48,6 +51,7 @@ export function Avatar({
       data-buzz-ui=""
       className="buzz-avatar"
       data-size={size}
+      data-avatar-shape={shape}
       role="img"
       aria-label={alt}
     >
diff --git a/src/shared/design-system/ui/registry.ts b/src/shared/design-system/ui/registry.ts
index 4cd26ef2..8895c29a 100644
--- a/src/shared/design-system/ui/registry.ts
+++ b/src/shared/design-system/ui/registry.ts
@@ -178,9 +178,10 @@ export const COMPONENTS: readonly ComponentDefinition[] = [
   {
     slug: "avatar",
     name: "Avatar",
-    purpose: "A person or agent identity image with a stable fallback.",
+    purpose:
+      "A person or agent identity image with a stable fallback. Circle by default; callers can select the proposed squircle shape from display-only agent evidence.",
     behavior: "Base UI Avatar",
-    variants: ["small", "default", "large", "fill"],
+    variants: ["small", "default", "large", "fill", "circle", "squircle"],
     status: "proposed",
     collection: "components",
     owner: "desktop-new Messages",
diff --git a/tests/browser/agents.spec.mjs b/tests/browser/agents.spec.mjs
index 7c69a256..b4b91afc 100644
--- a/tests/browser/agents.spec.mjs
+++ b/tests/browser/agents.spec.mjs
@@ -33,6 +33,9 @@ test("My agents reads the existing library with exact linked keys and session-sa
       .poll(() => agents.locator("img").evaluate((image) => image.naturalWidth))
       .toBeGreaterThan(0);
     await expect(agents.locator("img")).toHaveCSS("opacity", "1");
+    await expect(agents.locator("[data-avatar-shape]")).toHaveCount(2);
+    for (const avatar of await agents.locator("[data-avatar-shape]").all())
+      await expect(avatar).toHaveAttribute("data-avatar-shape", "squircle");
     await expect(
       agents.getByRole("img", { name: "A Brain", exact: true }),
     ).toHaveCount(2);
diff --git a/tests/browser/avatar-shapes.spec.mjs b/tests/browser/avatar-shapes.spec.mjs
new file mode 100644
index 00000000..b6e767f8
--- /dev/null
+++ b/tests/browser/avatar-shapes.spec.mjs
@@ -0,0 +1,213 @@
+import { expect, test } from "@playwright/test";
+import { createServer } from "./vite-server.mjs";
+import react from "@vitejs/plugin-react";
+import { fileURLToPath } from "node:url";
+
+// Sample actual browser paint, not just shape attributes or bounding boxes.
+async function pixels(page, locator, inset = 0) {
+  await locator.scrollIntoViewIfNeeded();
+  const bounds = await locator.boundingBox();
+  // Browser crops round outward to device pixels. Keep the fractional artwork
+  // origin rather than treating that rounded image as the avatar's own bounds.
+  const clip = {
+    x: Math.floor(bounds.x),
+    y: Math.floor(bounds.y),
+    width: Math.ceil(bounds.x + bounds.width) - Math.floor(bounds.x),
+    height: Math.ceil(bounds.y + bounds.height) - Math.floor(bounds.y),
+  };
+  const png = await page.screenshot({ clip, scale: "css" });
+  return page.evaluate(
+    async ({ base64, inset, bounds, clip }) => {
+      const image = new Image();
+      image.src = `data:image/png;base64,${base64}`;
+      await image.decode();
+      const canvas = document.createElement("canvas");
+      canvas.width = image.width;
+      canvas.height = image.height;
+      const context = canvas.getContext("2d");
+      context.drawImage(image, 0, 0);
+      const at = (fraction) => [
+        ...context.getImageData(
+          Math.floor(
+            bounds.x - clip.x + inset + (bounds.width - 2 * inset) * fraction,
+          ),
+          Math.floor(
+            bounds.y - clip.y + inset + (bounds.height - 2 * inset) * fraction,
+          ),
+          1,
+          1,
+        ).data,
+      ];
+      // One pixel inside the inset exposes a missing inner clip; its exact
+      // outermost corner can still be clipped by the parent's mask alone.
+      return {
+        corner: at(inset ? 0.05 : 0),
+        shoulder: at(0.1),
+        center: at(0.5),
+      };
+    },
+    { base64: png.toString("base64"), inset, bounds, clip },
+  );
+}
+
+test("avatar shapes paint at every size and preserve pointer/keyboard profile controls", async ({
+  page,
+  browserName,
+}, testInfo) => {
+  const server = await createServer({
+    root: fileURLToPath(new URL("../../", import.meta.url)),
+    configFile: false,
+    envFile: false,
+    plugins: [react()],
+    logLevel: "error",
+    server: { host: "127.0.0.1", port: 0 },
+  });
+  try {
+    await server.listen();
+    await page.goto(
+      `http://127.0.0.1:${server.httpServer.address().port}/tests/fixtures/avatar-shapes.html`,
+    );
+    const avatars = page.locator("[data-avatar-shape]");
+    await expect(avatars).toHaveCount(15);
+    for (const image of await avatars.locator("img").all()) {
+      await expect
+        .poll(() => image.evaluate((el) => el.complete && el.naturalWidth > 0))
+        .toBe(true);
+      await expect(image).toHaveCSS("opacity", "1");
+    }
+    const system = page.getByRole("region", { name: "System avatars" });
+    const insetAvatars = page.locator(
+      "button[aria-label^='View thread:'] [data-avatar-shape], [data-membership-row] [data-avatar-shape]",
+    );
+    await expect(insetAvatars).toHaveCount(4);
+    async function expectInsetArtwork(pictures = true) {
+      for (const avatar of await insetAvatars.all()) {
+        const shape = await avatar.getAttribute("data-avatar-shape");
+        const size = await avatar.evaluate((el) =>
+          el.closest("[data-membership-row]") ? 28 : 24,
+        );
+        await expect(avatar).toHaveCSS("width", `${size}px`);
+        await expect(avatar).toHaveCSS("height", `${size}px`);
+        await expect(avatar).toHaveCSS("border-width", "2px");
+        for (const image of await avatar.locator("img").all()) {
+          await expect(image).toHaveCSS("width", `${size - 4}px`);
+          await expect(image).toHaveCSS("height", `${size - 4}px`);
+        }
+        // Sample inside the overlap border: an outer mask alone leaves the
+        // actual image/fallback corners square even when its CSS says squircle.
+        const paint = await pixels(page, avatar, 2);
+        const surface = await avatar.evaluate((el) => {
+          const rgb = getComputedStyle(el)
+            .borderTopColor.match(/\d+/g)
+            .map(Number);
+          return [...rgb.slice(0, 3), 255];
+        });
+        const artwork = pictures
+          ? [255, 0, 255, 255]
+          : await avatar
+              .locator("span")
+              .first()
+              .evaluate((el) => {
+                const rgb = getComputedStyle(el)
+                  .backgroundColor.match(/\d+/g)
+                  .map(Number);
+                return [...rgb.slice(0, 3), 255];
+              });
+        // Edge pixels are antialiased at these tiny sizes. Compare whether the
+        // pixel is mostly background or artwork, rather than demanding zero
+        // coverage at the boundary (or confusing photo texture with clipping).
+        const distance = (pixel, color) =>
+          pixel.reduce((sum, value, i) => sum + (value - color[i]) ** 2, 0);
+        expect(
+          distance(paint.corner, surface),
+          `${shape}: inset corner is clipped`,
+        ).toBeLessThan(distance(paint.corner, artwork));
+        if (pictures)
+          expect(paint.center, "inset picture is painted").toEqual(artwork);
+        if (shape === "squircle")
+          // At 20px the shoulder itself can be mostly antialiasing. It must
+          // still paint beyond the clipped corner, not promise full coverage.
+          expect(
+            distance(paint.shoulder, artwork),
+            "inset squircle retains its shoulder",
+          ).toBeLessThan(distance(paint.corner, artwork));
+        else
+          expect(
+            distance(paint.shoulder, surface),
+            "inset human avatar stays circular",
+          ).toBeLessThan(distance(paint.shoulder, artwork));
+      }
+    }
+    for (const mode of ["light", "dark"]) {
+      await page.evaluate((mode) => {
+        document.documentElement.dataset.colorMode = mode;
+      }, mode);
+      for (const width of [390, 900, 1280]) {
+        await page.setViewportSize({ width, height: 800 });
+        for (const avatar of await avatars.all()) {
+          const shape = await avatar.getAttribute("data-avatar-shape");
+          await expect(avatar).toHaveCSS("clip-path", "none");
+          await expect(avatar).toHaveCSS(
+            "border-radius",
+            shape === "squircle" ? "0px" : "50%",
+          );
+          await expect(avatar).toHaveCSS(
+            "mask-image",
+            shape === "squircle" ? /^url\(/ : "none",
+          );
+        }
+        await expectInsetArtwork();
+        for (const avatar of await system
+          .locator("[data-avatar-shape]")
+          .all()) {
+          const shape = await avatar.getAttribute("data-avatar-shape");
+          const paint = await pixels(page, avatar);
+          expect(
+            paint.center,
+            `${mode}/${width}/${shape}: artwork is painted`,
+          ).not.toEqual(paint.corner);
+          if (shape === "squircle")
+            expect(
+              paint.shoulder,
+              "squircle extends beyond a circle",
+            ).not.toEqual(paint.corner);
+          else
+            expect(paint.shoulder, "human corner stays circular").toEqual(
+              paint.corner,
+            );
+        }
+      }
+    }
+    await page.getByRole("checkbox", { name: "Show pictures" }).uncheck();
+    await expect(insetAvatars.locator("img")).toHaveCount(0);
+    await expectInsetArtwork(false);
+    await page.getByRole("checkbox", { name: "Show pictures" }).check();
+    const button = page.getByRole("button", { name: "View Agent profile" });
+    await expect(button).toHaveCSS("background-color", "rgba(0, 0, 0, 0)");
+    await button.hover();
+    await expect(button).toHaveCSS("background-color", "rgba(0, 0, 0, 0)");
+    await button.click();
+    await expect(page.getByRole("status")).toHaveText("Profile opened");
+    await expect(button).toHaveCSS("outline-style", "none");
+    await page.getByRole("button", { name: "Before avatars" }).focus();
+    // Safari on macOS uses Option-Tab to include all controls, like the other focus journeys.
+    await page.keyboard.press(
+      browserName === "webkit" && process.platform === "darwin"
+        ? "Alt+Tab"
+        : "Tab",
+    );
+    await expect(button).toBeFocused();
+    await expect(button).toHaveCSS("outline-style", "solid");
+    await expect(button).toHaveCSS("outline-width", "2px");
+    await expect(button).toHaveCSS("mask-image", "none");
+    await expect(button).toHaveCSS("clip-path", "none");
+    await expect(button).toHaveCSS("overflow", "visible");
+    await page.keyboard.press("Enter");
+    await expect(page.getByRole("status")).toHaveText("Profile opened");
+    await page.screenshot({
+      path: testInfo.outputPath("avatar-shapes-dark-keyboard.png"),
+    });
+  } finally {
+    await server.close();
+  }
+});
diff --git a/tests/browser/fixture.mjs b/tests/browser/fixture.mjs
index 3a265bf2..7259ddaf 100644
--- a/tests/browser/fixture.mjs
+++ b/tests/browser/fixture.mjs
@@ -430,6 +430,7 @@ export const test = base.extend({
                 [],
                 JSON.stringify({
                   name: key === membershipKeys[0] ? "Pinky" : "Brain",
+                  ...(key === membershipKeys[1] ? { is_agent: true } : {}),
                 }),
                 key,
               ),
diff --git a/tests/browser/membership.spec.mjs b/tests/browser/membership.spec.mjs
index 01f5b909..d7de5956 100644
--- a/tests/browser/membership.spec.mjs
+++ b/tests/browser/membership.spec.mjs
@@ -26,6 +26,16 @@ test("Channels renders grouped history and live membership without turning activ
     "Pinky added by you, along with Brain",
   );
   await expect(groups.locator("button")).toHaveCount(0);
+  const avatars = groups.first().locator("[data-avatar-shape]");
+  await expect(avatars).toHaveCount(2);
+  await expect(avatars.filter({ hasText: "PI" })).toHaveAttribute(
+    "data-avatar-shape",
+    "circle",
+  );
+  await expect(avatars.filter({ hasText: "BR" })).toHaveAttribute(
+    "data-avatar-shape",
+    "squircle",
+  );
   const centered = await groups.first().evaluate((row) => {
     const content = row.querySelector("p");
     const avatars = row.querySelector('[aria-hidden="true"]');
diff --git a/tests/browser/messages.spec.mjs b/tests/browser/messages.spec.mjs
index ce55d5cd..07f74ca7 100644
--- a/tests/browser/messages.spec.mjs
+++ b/tests/browser/messages.spec.mjs
@@ -7,7 +7,7 @@ import { fileURLToPath } from "node:url";
 // thread reader and durable outbox. No developer env, broker, credentials or relay.
 test("shared thread UI auto-loads, follows live replies, retries and isolates retargeted drafts", async ({
   page,
-}) => {
+}, testInfo) => {
   const server = await createServer({
     root: fileURLToPath(new URL("../../", import.meta.url)),
     configFile: false,
@@ -55,6 +55,13 @@ test("shared thread UI auto-loads, follows live replies, retries and isolates re
       exact: true,
     });
     const history = panel.getByRole("region", { name: "Thread messages" });
+    const feedAuthorAvatar = feed.locator(
+      '[data-message-id="ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff"] [data-avatar-shape]',
+    );
+    await expect(feedAuthorAvatar).toHaveAttribute(
+      "data-avatar-shape",
+      "circle",
+    );
     const draft = panel.getByRole("textbox", {
       name: "Reply to thread",
       exact: true,
@@ -110,6 +117,46 @@ test("shared thread UI auto-loads, follows live replies, retries and isolates re
     await expect(
       history.getByRole("heading", { name: "Agent Markdown", level: 3 }),
     ).toBeVisible();
+    const threadAgentAvatar = history
+      .getByRole("heading", { name: "Agent Markdown" })
+      .locator("xpath=ancestor::*[@data-message-id][1]")
+      .locator("[data-avatar-shape]")
+      .first();
+    await expect(threadAgentAvatar).toHaveAttribute(
+      "data-avatar-shape",
+      "squircle",
+    );
+    const threadHumanAvatar = history
+      .getByText("First root", { exact: true })
+      .locator("xpath=ancestor::*[@data-message-id][1]")
+      .locator("[data-avatar-shape]")
+      .first();
+    await expect(threadHumanAvatar).toHaveAttribute(
+      "data-avatar-shape",
+      "circle",
+    );
+    await page.evaluate(() => {
+      document.documentElement.dataset.colorMode = "dark";
+    });
+    const evidence = testInfo.outputPath("human-agent-thread-avatars.png");
+    const humanBox = await threadHumanAvatar.boundingBox();
+    const agentBox = await threadAgentAvatar.boundingBox();
+    const panelBox = await panel.boundingBox();
+    if (!humanBox || !agentBox || !panelBox)
+      throw new Error("Missing avatar evidence bounds");
+    const top = Math.max(0, Math.min(humanBox.y, agentBox.y) - panelBox.y - 36);
+    const bottom =
+      Math.max(humanBox.y + humanBox.height, agentBox.y + agentBox.height) -
+      panelBox.y +
+      72;
+    await panel.screenshot({
+      path: evidence,
+      clip: { x: 0, y: top, width: 440, height: bottom - top },
+    });
+    await testInfo.attach("human-agent-thread-avatars", {
+      path: evidence,
+      contentType: "image/png",
+    });
     await expect(
       history.getByText("Rendered from an agent envelope", { exact: true }),
     ).toHaveCSS("font-weight", /^(650|700)$/);
diff --git a/tests/browser/profiles.spec.mjs b/tests/browser/profiles.spec.mjs
index 35df65c2..d3ac0883 100644
--- a/tests/browser/profiles.spec.mjs
+++ b/tests/browser/profiles.spec.mjs
@@ -20,6 +20,10 @@ test("profile plumbing: exact avatar/mention targets, thread enrichment, lifecyc
     exact: true,
   });
   await expect(avatar).toHaveCount(1);
+  await expect(avatar.locator("[data-avatar-shape]")).toHaveAttribute(
+    "data-avatar-shape",
+    "circle",
+  );
   await avatar.focus();
   await avatar.press("Enter");
   await expect(key).toHaveText(npubs.viewer);
@@ -94,6 +98,10 @@ test("profile plumbing: exact avatar/mention targets, thread enrichment, lifecyc
   });
   await mention.click();
   await expect(key).toHaveText(npubs.mic);
+  await expect(panel.locator("[data-avatar-shape]")).toHaveAttribute(
+    "data-avatar-shape",
+    "circle",
+  );
   await panel.getByRole("button", { name: "Close channel panel" }).click();
   await expect(mention).toBeFocused();
   await mention.press("Space");
@@ -123,6 +131,13 @@ test("profile plumbing: exact avatar/mention targets, thread enrichment, lifecyc
   await expect(threadMention).toBeVisible();
   await threadMention.click();
   await expect(key).toHaveText(npubs.pinky);
+  await expect(panel.locator("[data-avatar-shape]")).toHaveAttribute(
+    "data-avatar-shape",
+    "squircle",
+  );
+  await expect(
+    panel.getByRole("img", { name: "Pinky avatar" }),
+  ).toHaveAttribute("data-size", "fill");
   await expect(panel.getByText("Agent profile", { exact: true })).toBeVisible();
   await panel.getByRole("button", { name: "Close channel panel" }).click();
   await expect(
diff --git a/tests/browser/typeahead.spec.mjs b/tests/browser/typeahead.spec.mjs
index 69ac6f4a..b831e8c8 100644
--- a/tests/browser/typeahead.spec.mjs
+++ b/tests/browser/typeahead.spec.mjs
@@ -4,6 +4,85 @@ const open = async (page) => {
   await page.goto("/tests/fixtures/mentions.html");
   return page.getByRole("textbox", { name: "Message #General" });
 };
+const expectAvatarShape = async (target, shape) => {
+  await expect(target.locator("[data-avatar-shape]")).toHaveAttribute(
+    "data-avatar-shape",
+    shape,
+  );
+};
+test("mention completion distinguishes exact agent identity without reshaping a namesake human", async ({
+  page,
+}) => {
+  const input = await open(page);
+  const keys = await page.evaluate(() => ({
+    human: window.mentionFixture.first,
+    agent: window.mentionFixture.second,
+  }));
+  await input.fill("@Ho");
+  await expectAvatarShape(
+    page.getByRole("option", { name: `Honey ${keys.human}`, exact: true }),
+    "circle",
+  );
+  await expectAvatarShape(
+    page.getByRole("option", { name: `Honey ${keys.agent}`, exact: true }),
+    "squircle",
+  );
+  await input.fill("");
+  await page
+    .getByRole("button", { name: "Mention a member", exact: true })
+    .click();
+  const picker = page.getByRole("region", { name: "Mention a channel member" });
+  await expectAvatarShape(
+    picker.getByRole("button", { name: `Honey ${keys.human}`, exact: true }),
+    "circle",
+  );
+  await expectAvatarShape(
+    picker.getByRole("button", { name: `Honey ${keys.agent}`, exact: true }),
+    "squircle",
+  );
+});
+test("open completion republishes library-only display hints without changing the query", async ({
+  page,
+}) => {
+  const input = await open(page);
+  const keys = await page.evaluate(() => ({
+    first: window.mentionFixture.first,
+    second: window.mentionFixture.second,
+  }));
+  await input.fill("@Ho");
+  const first = page.getByRole("option", {
+    name: `Honey ${keys.first}`,
+    exact: true,
+  });
+  const second = page.getByRole("option", {
+    name: `Honey ${keys.second}`,
+    exact: true,
+  });
+  await expectAvatarShape(first, "circle");
+  await expectAvatarShape(second, "squircle");
+  // Opening completion subscribes to the library; it must not load it.
+  expect(await page.evaluate(() => window.mentionFixture.libraryReads())).toBe(
+    0,
+  );
+
+  for (const [included, reads] of [
+    [true, 1],
+    [false, 2],
+  ]) {
+    await page.evaluate(
+      (included) => window.mentionFixture.setLibraryAgent(included),
+      included,
+    );
+    await expectAvatarShape(first, included ? "squircle" : "circle");
+    await expectAvatarShape(second, "squircle");
+    await expect(input).toHaveText("@Ho");
+    await expect(input).toBeFocused();
+    await expect(page.getByRole("listbox")).toBeVisible();
+    expect(
+      await page.evaluate(() => window.mentionFixture.libraryReads()),
+    ).toBe(reads);
+  }
+});
 
 for (const mode of ["light", "dark"]) {
   for (const kind of ["mention", "emoji"]) {
diff --git a/tests/fixtures/avatar-shapes.html b/tests/fixtures/avatar-shapes.html
new file mode 100644
index 00000000..cd834f87
--- /dev/null
+++ b/tests/fixtures/avatar-shapes.html
@@ -0,0 +1 @@
+<!doctype html><html lang="en"><head><meta charset="UTF-8"><title>Avatar shapes</title></head><body><div id="root"></div><script type="module" src="./avatar-shapes.tsx"></script></body></html>
diff --git a/tests/fixtures/avatar-shapes.tsx b/tests/fixtures/avatar-shapes.tsx
new file mode 100644
index 00000000..9e68ec49
--- /dev/null
+++ b/tests/fixtures/avatar-shapes.tsx
@@ -0,0 +1,126 @@
+// Real avatar consumers with local display-only data, no session/broker/network reads.
+import "../../src/shared/styles/globals.css";
+import { useState } from "react";
+import { createRoot } from "react-dom/client";
+import { Avatar } from "../../src/shared/design-system/ui/Avatar";
+import { Avatar as LegacyAvatar } from "../../src/shared/Avatar";
+import { useKeyboardFocusVisibility } from "../../src/shared/design-system/useKeyboardFocusVisibility";
+import { MessageRow } from "../../src/features/messages/MessageRow";
+import { MembershipRow } from "../../src/features/messages/MembershipRow";
+import type { ChannelMessage } from "../../src/features/relay/contracts";
+import artwork from "./design-system/assets/avatar.png";
+
+const agent = "a".repeat(64),
+  human = "b".repeat(64);
+// Flat color lets the paint test distinguish clipping from photo texture.
+const insetArtwork = `data:image/svg+xml,${encodeURIComponent(
+  '<svg xmlns="http://www.w3.org/2000/svg" width="32" height="32"><path fill="#ff00ff" d="M0 0h32v32H0z"/></svg>',
+)}`;
+const profiles = new Map([
+  [agent, { name: "Agent", picture: insetArtwork }],
+  [human, { name: "Human", picture: insetArtwork }],
+]);
+const agentPubkeys = new Set([agent]);
+const row: ChannelMessage = {
+  id: "message",
+  authorId: agent,
+  channelId: "fixture",
+  createdAt: 1,
+  content: "A message",
+  mentions: [],
+  attachments: [],
+  reactions: [],
+  participants: [agent, human],
+  replyCount: 2,
+};
+function Fixture() {
+  useKeyboardFocusVisibility();
+  const [opened, setOpened] = useState(false);
+  const [pictures, setPictures] = useState(true);
+  return (
+    // Match the message panel's opaque surface so clipped pixels have the same
+    // backdrop as the overlap border in either theme, not the document canvas.
+    <main style={{ padding: 24, background: "var(--surface)" }}>
+      <button type="button">Before avatars</button>
+      <section
+        aria-label="System avatars"
+        style={{ display: "flex", flexWrap: "wrap", gap: 16, marginBlock: 24 }}
+      >
+        {(["small", "default", "large", "fill"] as const).flatMap((size) =>
+          (["circle", "squircle"] as const).map((shape) => (
+            <div
+              key={`${size}-${shape}`}
+              style={size === "fill" ? { width: 128, height: 128 } : undefined}
+            >
+              <Avatar
+                size={size}
+                shape={shape}
+                src={size === "small" ? undefined : artwork}
+                alt={`${size} ${shape}`}
+                fallback="Avatar"
+              />
+            </div>
+          )),
+        )}
+      </section>
+      <section
+        aria-label="Legacy avatars"
+        style={{ display: "flex", flexWrap: "wrap", gap: 16, marginBlock: 24 }}
+      >
+        <LegacyAvatar
+          name="Human"
+          src={artwork}
+          shape="circle"
+          className="size-7 rounded-lg"
+        />
+        <LegacyAvatar
+          name="Agent"
+          src={artwork}
+          shape="squircle"
+          className="size-7 rounded-lg"
+        />
+      </section>
+      <MessageRow
+        row={{ ...row, agentEnvelope: true }}
+        profile={profiles.get(agent)}
+        participantProfiles={profiles}
+        agentPubkeys={agentPubkeys}
+        media={(url) => (pictures ? url : undefined)}
+        canOpenLink={() => true}
+        onOpenLink={() => {
+          setOpened(true);
+          return true;
+        }}
+        day={false}
+        retry={undefined}
+        onOpenThread={() => {}}
+      />
+      {[agent, human].map((target) => (
+        <MembershipRow
+          key={target}
+          row={{
+            ...row,
+            id: `membership-${target}`,
+            membership: { type: "member_joined", actor: agent, target },
+          }}
+          profiles={profiles}
+          agentPubkeys={agentPubkeys}
+          media={(url) => (pictures ? url : undefined)}
+          day={false}
+        />
+      ))}
+      <label>
+        <input
+          type="checkbox"
+          checked={pictures}
+          onChange={(event) => setPictures(event.currentTarget.checked)}
+        />
+        Show pictures
+      </label>
+      {opened && <p role="status">Profile opened</p>}
+    </main>
+  );
+}
+const root = document.getElementById("root");
+if (!root) throw new Error("Missing fixture root");
+createRoot(root).render(<Fixture />);
diff --git a/tests/fixtures/design-system/ui/componentSpecimens.tsx b/tests/fixtures/design-system/ui/componentSpecimens.tsx
index a3a1731c..ab7e4bf6 100644
--- a/tests/fixtures/design-system/ui/componentSpecimens.tsx
+++ b/tests/fixtures/design-system/ui/componentSpecimens.tsx
@@ -302,6 +302,21 @@ function AvatarSpecimen() {
           </Specimen>
         </div>
       </SpecimenGroup>
+      <SpecimenGroup label="Agent shape (proposed)">
+        <div className="component-specimen-row">
+          <Specimen prop='shape="squircle"'>
+            <Avatar
+              src={avatarUrl}
+              alt="Agent artwork"
+              fallback="Agent"
+              shape="squircle"
+            />
+          </Specimen>
+          <Specimen prop='shape="squircle", no src'>
+            <Avatar alt="Agent fallback" fallback="Agent" shape="squircle" />
+          </Specimen>
+        </div>
+      </SpecimenGroup>
       {/* No `src`, so the fallback initial shows. Same three sizes, because a
           fallback has to hold the ramp as well as an image does. */}
       <SpecimenGroup label="Fallback, with no src">
diff --git a/tests/fixtures/mentions.tsx b/tests/fixtures/mentions.tsx
index 2b0f6ca5..b700acca 100644
--- a/tests/fixtures/mentions.tsx
+++ b/tests/fixtures/mentions.tsx
@@ -26,6 +26,8 @@ let time = 1700000000;
 const publications: RelayEvent[] = [];
 let incoming = (_events: readonly RelayEvent[]) => {};
 let releaseProfiles = () => {};
+let libraryReads = 0;
+let libraryIncludesFirst = false;
 const delayed = new URLSearchParams(location.search).has("delayed-profiles");
 const profileGate = delayed
   ? new Promise<void>((resolve) => {
@@ -37,6 +39,16 @@ const owner = createRelaySession(
     viewer: viewer.pubkey,
     relayAuthor: relay.pubkey,
     media: (url) => url,
+    // Synthetic, lazy capability: only the explicit fixture action loads it.
+    async readAgentLibrary() {
+      libraryReads++;
+      return {
+        definitions: [],
+        identities: libraryIncludesFirst
+          ? [{ pubkey: first.pubkey, name: "Honey" }]
+          : [],
+      };
+    },
     subscribe(callbacks) {
       incoming = callbacks.receive;
       callbacks.state({ status: "connected", routes: [] });
@@ -52,7 +64,7 @@ const owner = createRelaySession(
         metadata(relay, "other", "Other"),
         profile(viewer, { name: "Viewer" }),
         profile(first, { name: delayed ? "Mary Jane" : "Honey" }),
-        profile(second, { name: "Honey" }),
+        profile(second, { name: "Honey", is_agent: true }),
         ...publications,
       ];
       return events.filter((event) =>
@@ -138,6 +150,11 @@ Object.assign(window, {
       owner.session.channels.refreshList?.();
     },
     releaseProfiles: () => releaseProfiles(),
+    libraryReads: () => libraryReads,
+    setLibraryAgent(included: boolean) {
+      libraryIncludesFirst = included;
+      return owner.session.agentLibrary.refresh();
+    },
     list: () => owner.session.channels.list(),
     otherMessage() {
       incoming([message(viewer, "other", "Unrelated preview", ++time)]);
diff --git a/tests/fixtures/messages.tsx b/tests/fixtures/messages.tsx
index a102fe2e..2d339ba8 100644
--- a/tests/fixtures/messages.tsx
+++ b/tests/fixtures/messages.tsx
@@ -132,7 +132,10 @@ const owner = createRelaySession({
           metadata(relay, "two", "Two"),
         ];
       if (filter.kinds?.includes(0))
-        return [profile(viewer, { name: "Fixture Reader" })];
+        return [
+          profile(viewer, { name: "Fixture Reader" }),
+          profile(agent, { name: "Agent Fixture" }),
+        ].filter((event) => filter.authors?.includes(event.pubkey));
       if (filter.ids)
         return events.filter((event) => filter.ids?.includes(event.id));
       if (filter.depth_limit) {
diff --git a/tests/fixtures/profiles.tsx b/tests/fixtures/profiles.tsx
index 3b4cf469..747a21ce 100644
--- a/tests/fixtures/profiles.tsx
+++ b/tests/fixtures/profiles.tsx
@@ -50,7 +50,12 @@ let failMissing = true;
 const data = [
   profile(viewer, { name: "Viewer", about: "Human profile", picture }),
   profile(mic, { name: "Mic", about: "Mic biography" }),
-  profile(pinky, { name: "Pinky", about: "Agent profile" }),
+  profile(pinky, {
+    name: "Pinky",
+    about: "Agent profile",
+    is_agent: true,
+    picture,
+  }),
 ];
 function session() {
   return createRelaySession({