fix(desktop): never show a trigger title as the prompt author

The conversation variant's author row resolved its name through
`resolveUserLabel({ fallbackName: item.title })`, whose last fallback is
the prompt item's title. That title describes the *trigger* that started
the turn — "@Mention", "Prompt", "Buzz event", or any title-cased Buzz
event kind — and is never an identity. On `default`/`compactPreview` it
only seeds avatar initials, so it was harmless; the conversation author
row promotes it to displayed text, so an unresolved sender was rendered
as if "@Mention" were their name.

Identity resolution for the displayed author now stops at the profile:
display name, then NIP-05 handle, then the truncated pubkey. A truncated
pubkey is terse but true, and it keeps the utterance attributed in a
full-cover view where an unlabelled bubble would read as orphaned. The
title stays available as trigger chrome in the footer.

The avatar seed keeps the old chain verbatim, so `default` and
`compactPreview` markup is untouched — the byte-for-byte fixture still
passes unchanged.

The existing author-row test was asserting the bug: its expectation came
from `item.title`, with no profile in the lookup. It now supplies a
profile and asserts the resolved display name, and the fixture's prompt
title is the realistic "@Mention" rather than a person's name so no test
can silently depend on a title reading as an identity again. Two new
tests cover the unresolved sender (truncated pubkey, and an explicit
assertion that no trigger word appears) and NIP-05-only resolution.

Non-vacuous: reverting the fix fails the unresolved-sender test — and
only that test — with `actual: '@Mention'`.

Verified at this tree: full desktop suite 5381 passing / 0 failing,
typecheck clean, `pnpm check` findings identical to main's baseline,
file-size ratchet clean. Transcript file also green under UTC/de-DE and
Asia/Tokyo/ja-JP.

Signed-off-by: ss-dev-01 <11939edb7df583f855dbef923f2358f1184538f88ca452e19e7e35e42ad6d796@buzz.block.builderlab.xyz>
Co-authored-by: Bradley Axen <baxen@squareup.com>
Signed-off-by: Bradley Axen <baxen@squareup.com>

desktop/src/features/agents/ui/AgentSessionTranscriptList.conversation.test.mjs

@@ -139,6 +139,23 @@ const AGENT = {
   agentPubkey: "f".repeat(64),
 };
 const AUTHOR = "a".repeat(64);
+const AUTHOR_TRUNCATED = `${AUTHOR.slice(0, 8)}…${AUTHOR.slice(-4)}`;
+/**
+ * What the transcript builder actually puts in a prompt item's `title`: a
+ * description of the trigger that started the turn, not an identity. Real values
+ * are "Prompt", "Buzz event", and title-cased event kinds like "@Mention"
+ * (`agentSessionTranscriptHelpers.ts` `parsePromptText`). The author row must
+ * never display this as a name.
+ */
+const TRIGGER_TITLE = "@Mention";
+const AUTHOR_PROFILES = {
+  [AUTHOR]: {
+    displayName: "Ada Lovelace",
+    avatarUrl: null,
+    nip05Handle: null,
+    ownerPubkey: null,
+  },
+};
 
 function items() {
   const shared = { channelId: "chan-1", sessionId: "sess-1", turnId: "turn-1" };
@@ -149,7 +166,7 @@ function items() {
       type: "message",
       renderClass: "message",
       role: "user",
-      title: "Ada",
+      title: TRIGGER_TITLE,
       text: "please summarize the plan",
       timestamp: "2026-06-14T19:00:00.000Z",
       messageId: "event-1",
@@ -426,12 +443,14 @@ test("conversation marks the transcript container and centers a reading column",
 });
 
 test("conversation renders the prompt as a filled right-aligned bubble with an author label", async () => {
-  const { container } = await renderTranscript("conversation");
+  const { container } = await renderTranscript("conversation", {
+    profiles: AUTHOR_PROFILES,
+  });
   const author = container.querySelector(
     '[data-testid="transcript-user-message-author"]',
   );
   assert.ok(author, "conversation should label the prompt author");
-  assert.equal(author.textContent, "Ada");
+  assert.equal(author.textContent, "Ada Lovelace");
 
   const row = container.querySelector(
     '[data-testid="transcript-user-message"]',
@@ -443,6 +462,48 @@ test("conversation renders the prompt as a filled right-aligned bubble with an a
   assert.doesNotMatch(bubble.className, /max-h-36/);
 });
 
+test("conversation never shows the trigger title as the prompt author when the sender is unresolved", async () => {
+  // Regression guard. The label chain's last fallback used to be the prompt
+  // item's `title`, which is a description of the trigger ("@Mention",
+  // "Prompt", "Buzz event") rather than an identity. On the other variants that
+  // string only seeds avatar initials, so it was harmless; the conversation
+  // author row displays it, so an unresolved sender was rendered as "@Mention"
+  // — a trigger presented as a person's name. With no profile for the author,
+  // the row must fall back to the truncated pubkey instead.
+  const { container } = await renderTranscript("conversation");
+  const author = container.querySelector(
+    '[data-testid="transcript-user-message-author"]',
+  );
+  assert.ok(author, "the author row should still render without a profile");
+  assert.equal(author.textContent, AUTHOR_TRUNCATED);
+  assert.doesNotMatch(
+    author.textContent,
+    /@Mention|Prompt|Buzz event/,
+    "the trigger title must never be displayed as an author name",
+  );
+});
+
+test("conversation prefers the resolved profile over both the trigger title and the pubkey", async () => {
+  // The truncated-pubkey fallback must not shadow a real identity: with a
+  // profile present the row shows the display name, and with only a NIP-05
+  // handle it shows that.
+  const { container } = await renderTranscript("conversation", {
+    profiles: {
+      [AUTHOR]: {
+        displayName: null,
+        avatarUrl: null,
+        nip05Handle: "ada@example.com",
+        ownerPubkey: null,
+      },
+    },
+  });
+  assert.equal(
+    container.querySelector('[data-testid="transcript-user-message-author"]')
+      .textContent,
+    "ada@example.com",
+  );
+});
+
 test("conversation renders agent messages as unboxed prose at full fidelity", async () => {
   const { container } = await renderTranscript("conversation");
   const message = container.querySelector(

desktop/src/features/agents/ui/activityRenderClasses/UserMessageBubble.tsx

@@ -50,13 +50,31 @@ export function UserMessageBubble({
   const authorProfile = item.authorPubkey
     ? profiles?.[item.authorPubkey.toLowerCase()]
     : null;
-  const authorLabel = item.authorPubkey
+  // The other variants seed the avatar from `resolveUserLabel(…, fallbackName:
+  // item.title)`, whose last resort is the prompt item's title. That title
+  // describes the *trigger* that started the turn ("@Mention", "Prompt", "Buzz
+  // event"), never a person — harmless when it only picks avatar initials, so
+  // this chain is left exactly as it was for `default`/`compactPreview`.
+  const triggerSeededLabel = item.authorPubkey
     ? resolveUserLabel({
         pubkey: item.authorPubkey,
         fallbackName: item.title,
         profiles,
       })
     : item.title || "User";
+  // Focus mode promotes the author to displayed text, where a trigger title
+  // would read as a false identity — an unresolved sender showing up as
+  // "@Mention". Identity resolution here therefore stops at the profile
+  // (display name, then NIP-05 handle, then the truncated pubkey): a truncated
+  // pubkey is a real, if terse, identity, and it keeps the utterance attributed
+  // in a full-cover view. `item.title` stays available as trigger chrome in the
+  // footer; it is never a name. Only when the item carries no author at all does
+  // the row fall back to a generic placeholder.
+  const authorLabel = isConversation
+    ? item.authorPubkey
+      ? resolveUserLabel({ pubkey: item.authorPubkey, profiles })
+      : "User"
+    : triggerSeededLabel;
   const handleBubbleClick = React.useCallback(
     (event: React.MouseEvent<HTMLDivElement>) => {
       if (!messageLink || isNestedInteractiveTarget(event)) return;