fix(desktop): retain drafts after synchronous mention extraction failure

Replay the approved first slice from 857ed203 and e0cc5522 (aggregate 58db416d). Keep extraction within failure cleanup; use the existing runtime lookup and upload error rendering through size-gate helper extractions. Remove the inherited unused markdown import for strict builds.

Co-authored-by: Larry <627498bd4bd1f281a16431e3c6cce3b5c25b6692798c78672298aefbf2f8f8b5@buzz.block.builderlab.xyz>
Signed-off-by: Logan Johnson <loganj@squareup.com>

desktop/src/features/messages/ui/ComposerUploadError.tsx

@@ -0,0 +1,20 @@
+import type { useMediaUpload } from "@/features/messages/lib/useMediaUpload";
+
+/** Display the upload failure without losing the composer's retry controls. */
+export function ComposerUploadError({
+  uploadState,
+  onDismiss,
+}: {
+  uploadState: ReturnType<typeof useMediaUpload>["uploadState"];
+  onDismiss: () => void;
+}) {
+  if (uploadState.status !== "error") return null;
+  return (
+    <div className="mb-2 rounded-lg bg-destructive/10 px-3 py-2 text-xs text-destructive">
+      Upload failed: {uploadState.message}
+      <button className="ml-2 underline" onClick={onDismiss} type="button">
+        Dismiss
+      </button>
+    </div>
+  );
+}

desktop/src/features/messages/ui/MessageComposer.tsx

@@ -52,6 +52,7 @@ import { ComposerAttachments, DropZoneOverlay } from "./ComposerAttachments";
 import { focusMentionOptionsTrigger } from "./MentionAutocomplete";
 import { MessageComposerAutocompletes } from "./MessageComposerAutocompletes";
 import { ComposerDockToolbar } from "./ComposerDockToolbar";
+import { ComposerUploadError } from "./ComposerUploadError";
 import { ComposerUploadProgressPill } from "./ComposerUploadProgressPill";
 import { NonMemberMentionDialog } from "./NonMemberMentionDialog";
 import { useComposerVoiceNote } from "./useComposerVoiceNote";
@@ -897,18 +898,10 @@ function MessageComposerImpl({
               onOptionsRevealComplete={completeMentionOptionsReveal}
               onToggleAlwaysAddressAgent={toggleAlwaysAddressAgent}
             />
-            {media.uploadState.status === "error" ? (
+            <ComposerUploadError
-              <div className="mb-2 rounded-lg bg-destructive/10 px-3 py-2 text-xs text-destructive">
+              uploadState={media.uploadState}
-                Upload failed: {media.uploadState.message}
+              onDismiss={() => media.setUploadState({ status: "idle" })}
-                <button
+            />
-                  className="ml-2 underline"
-                  onClick={() => media.setUploadState({ status: "idle" })}
-                  type="button"
-                >
-                  Dismiss
-                </button>
-              </div>
-            ) : null}
             {composerLinkPreviews}
             <output
               aria-live="polite"

desktop/src/features/messages/ui/useMentionAvailableRuntimes.ts

@@ -0,0 +1,28 @@
+import * as React from "react";
+import { useAvailableAcpRuntimes } from "@/features/agents/hooks";
+import type { AcpRuntime } from "@/shared/api/types";
+
+/** Resolve available runtimes for persona mentions without refetching warm data. */
+export function useMentionAvailableRuntimes() {
+  const availableRuntimesQuery = useAvailableAcpRuntimes();
+  const getAvailableRuntimes = React.useCallback(async (): Promise<
+    AcpRuntime[]
+  > => {
+    const cached = availableRuntimesQuery.data ?? [];
+    if (cached.length > 0 || !availableRuntimesQuery.isLoading) {
+      return cached;
+    }
+    const refetched = await availableRuntimesQuery.refetch();
+    return (refetched.data ?? []).filter(
+      (runtime): runtime is AcpRuntime =>
+        runtime.availability === "available" &&
+        runtime.command !== null &&
+        runtime.binaryPath !== null,
+    );
+  }, [
+    availableRuntimesQuery.data,
+    availableRuntimesQuery.isLoading,
+    availableRuntimesQuery.refetch,
+  ]);
+  return getAvailableRuntimes;
+}

desktop/src/features/messages/ui/useMentionSendFlow.authority.test.mjs

@@ -216,3 +216,35 @@ test("automatic addressed prefix is programmatic optimistic empty, not new autho
   assert.equal(s.store.get("thread:a").content, TEXT);
   assert.deepEqual(s.store.get("thread:a").mentionRefs, s.refs);
 });
+
+for (const extractor of [
+  "getDraftMentionRefs",
+  "extractMentionPubkeys",
+  "extractMentionPersonas",
+]) {
+  test(`synchronous ${extractor} failure is visible and releases the send latch`, async () => {
+    const s = await setup({ lifecycle: true });
+    s.dismiss();
+    s.options.mentions[extractor] = () => {
+      throw new Error("Choose an exact recipient");
+    };
+    s.rerender();
+    const input = {
+      capturedChannelId: "general",
+      pendingImeta: [],
+      trimmed: TEXT,
+      recoveryDraftKey: "thread:a",
+      sentDraftKey: "thread:a",
+    };
+    for (let attempt = 0; attempt < 2; attempt++) {
+      await s.act(async () =>
+        s.result.current.sendMessageWithMentionFlow(input),
+      );
+      assert.equal(s.result.current.isPreparingMentionSend, false);
+      assert.equal(s.options.contentRef.current, TEXT);
+      assert.equal(s.events("error").length, attempt + 1);
+      assert.equal(s.events("error").at(-1)[1], "Choose an exact recipient");
+      assert.equal(s.events("SEND").length, 0);
+    }
+  });
+}

desktop/src/features/messages/ui/useMentionSendFlow.test-support.mjs

@@ -159,6 +159,10 @@ export async function setup({ lifecycle = false } = {}) {
       AgentMentionAuthorizationError: class extends Error {},
     },
   };
+  stubs["./useMentionAvailableRuntimes"] = load(
+    "useMentionAvailableRuntimes",
+    stubs,
+  );
   stubs["./useNonMemberInvite"] = load("useNonMemberInvite", stubs);
   stubs["./useActivePreparedLinkPreviews"] = load(
     "useActivePreparedLinkPreviews",

desktop/src/features/messages/ui/useMentionSendFlow.ts

@@ -4,7 +4,6 @@ import { toast } from "sonner";
 import {
   type CreateChannelManagedAgentInput,
   useAttachManagedAgentToChannelMutation,
-  useAvailableAcpRuntimes,
   useCreateChannelManagedAgentMutation,
   useManagedAgentsQuery,
   usePersonasQuery,
@@ -15,6 +14,7 @@ import { applyReusableAgentAccessPolicy } from "@/features/agents/channelAgents"
 import { resolvePersonaRuntime } from "@/features/agents/lib/resolvePersonaRuntime";
 import { useAddChannelMembersMutation } from "@/features/channels/hooks";
 import { useCanAddChannelMembers } from "@/features/channels/useCanAddChannelMembers";
+import { useMentionAvailableRuntimes } from "./useMentionAvailableRuntimes";
 import { useNonMemberInvite } from "./useNonMemberInvite";
 import { dmThreadAgentMentionError } from "@/features/messages/lib/dmThreadAgentMentionError";
 import {
@@ -27,7 +27,7 @@ import {
 } from "@/features/messages/lib/imetaMediaMarkdown";
 import { useActivePreparedLinkPreviews } from "./useActivePreparedLinkPreviews";
 import { invokeTauri } from "@/shared/api/tauri";
-import type { AcpRuntime, ManagedAgent } from "@/shared/api/types";
+import type { ManagedAgent } from "@/shared/api/types";
 import { normalizePubkey, truncatePubkey } from "@/shared/lib/pubkey";
 import { buildCustomEmojiTags } from "@/shared/lib/customEmojiTags";
 import {
@@ -111,7 +111,6 @@ export function useMentionSendFlow({
     useCreateChannelManagedAgentMutation(channelId);
   const provisionPersonaAgentMutation =
     useProvisionChannelManagedAgentMutation(channelId);
-  const availableRuntimesQuery = useAvailableAcpRuntimes();
   const managedAgentsQuery = useManagedAgentsQuery();
   const personasQuery = usePersonasQuery();
   const startAgentMutation = useStartManagedAgentMutation();
@@ -127,25 +126,7 @@ export function useMentionSendFlow({
   const getPersonas = React.useCallback(async () => {
     return personasQuery.data ?? (await personasQuery.refetch()).data ?? [];
   }, [personasQuery.data, personasQuery.refetch]);
-  const getAvailableRuntimes = React.useCallback(async (): Promise<
+  const getAvailableRuntimes = useMentionAvailableRuntimes();
-    AcpRuntime[]
-  > => {
-    const cached = availableRuntimesQuery.data ?? [];
-    if (cached.length > 0 || !availableRuntimesQuery.isLoading) {
-      return cached;
-    }
-    const refetched = await availableRuntimesQuery.refetch();
-    return (refetched.data ?? []).filter(
-      (runtime): runtime is AcpRuntime =>
-        runtime.availability === "available" &&
-        runtime.command !== null &&
-        runtime.binaryPath !== null,
-    );
-  }, [
-    availableRuntimesQuery.data,
-    availableRuntimesQuery.isLoading,
-    availableRuntimesQuery.refetch,
-  ]);
   const ensureManagedAgentMentionsReady = React.useCallback(
     async (
       mentionPubkeys: string[],
@@ -669,7 +650,11 @@ export function useMentionSendFlow({
                 await finishSend(uploaded, signal);
               } catch (error) {
                 restoreComposerAfterFailure();
-                toast.error(error instanceof AgentMentionAuthorizationError ? error.message : formatMessageSendError(error));
+                toast.error(
+                  error instanceof AgentMentionAuthorizationError
+                    ? error.message
+                    : formatMessageSendError(error),
+                );
               } finally {
                 settleUpload();
               }
@@ -697,7 +682,11 @@ export function useMentionSendFlow({
             await finishSend([]);
           } catch (error) {
             restoreComposerAfterFailure();
-            toast.error(error instanceof AgentMentionAuthorizationError ? error.message : formatMessageSendError(error));
+            toast.error(
+              error instanceof AgentMentionAuthorizationError
+                ? error.message
+                : formatMessageSendError(error),
+            );
           }
         }
       } catch (error) {
@@ -762,20 +751,22 @@ export function useMentionSendFlow({
       }
       isMentionSendPendingRef.current = true;
       setIsMentionSendPending(true);
-      // Capture exact selections before any async preparation can navigate the
-      // reused editor to another draft (possibly with identical display text).
-      claimDraftSend(effectiveDraftKey);
-      const composerRevision = getComposerRevision();
-      const savedMentionRefs = mentions.getDraftMentionRefs(trimmed).slice();
-      const selectedMentionPubkeys = mentions.extractMentionPubkeys(trimmed);
-      const selectedPersonas = mentions.extractMentionPersonas(trimmed);
-      const isSendCancelled = () =>
-        preparedLinkPreviews?.signal.aborted === true;
       let sendPromoted = false;
-      if (preparedLinkPreviews) {
-        activePreparedLinkPreviews.add(preparedLinkPreviews);
-      }
       try {
+        // Capture exact selections before any async preparation can navigate the
+        // reused editor to another draft (possibly with identical display text).
+        // Ambiguous-name extraction can throw; it owns the same visible failure
+        // and pending-state cleanup as the asynchronous preparation below.
+        claimDraftSend(effectiveDraftKey);
+        const composerRevision = getComposerRevision();
+        const savedMentionRefs = mentions.getDraftMentionRefs(trimmed).slice();
+        const selectedMentionPubkeys = mentions.extractMentionPubkeys(trimmed);
+        const selectedPersonas = mentions.extractMentionPersonas(trimmed);
+        const isSendCancelled = () =>
+          preparedLinkPreviews?.signal.aborted === true;
+        if (preparedLinkPreviews) {
+          activePreparedLinkPreviews.add(preparedLinkPreviews);
+        }
         if (isSendCancelled()) return;
         const dmThreadAgentMentionErrorMessage = dmThreadAgentMentionError({
           trimmed,

desktop/src/shared/ui/markdown.tsx

@@ -14,7 +14,6 @@ import {
   type ParsedMessageLink,
 } from "@/features/messages/lib/messageLink";
 import { renderAudioMessageAttachment } from "@/features/messages/ui/AudioMessageAttachment";
-import { invokeTauri } from "@/shared/api/tauri";
 import { useChannelNavigation } from "@/shared/context/ChannelNavigationContext";
 import { cn } from "@/shared/lib/cn";
 import { parseEntityLink } from "@/shared/lib/entityLink";