diff --git a/src/components/nostr/ExternalIdentifierDisplay.tsx b/src/components/nostr/ExternalIdentifierDisplay.tsx
new file mode 100644
index 0000000..a7e0125
--- /dev/null
+++ b/src/components/nostr/ExternalIdentifierDisplay.tsx
@@ -0,0 +1,114 @@
+/**
+ * Shared UI components for displaying NIP-73 external content identifiers.
+ *
+ * Used by:
+ * - Kind 1111 (NIP-22 Comment) — root scope display
+ * - Kind 30385 (NIP-85 Trusted Assertion) — external subject display
+ */
+
+import {
+  getExternalIdentifierIcon,
+  getExternalIdentifierLabel,
+  getExternalIdentifierHref,
+  inferExternalIdentifierType,
+} from "@/lib/nip73-helpers";
+import { cn } from "@/lib/utils";
+
+/**
+ * Inline external identifier — icon + label, optionally linked.
+ * Compact version for feed renderers.
+ */
+export function ExternalIdentifierInline({
+  value,
+  kType,
+  hint,
+  className,
+}: {
+  value: string;
+  kType?: string;
+  hint?: string;
+  className?: string;
+}) {
+  const type = kType || inferExternalIdentifierType(value);
+  const Icon = getExternalIdentifierIcon(type);
+  const label = getExternalIdentifierLabel(value, type);
+  const href = getExternalIdentifierHref(value, hint);
+
+  const content = (
+    <>
+      <Icon className="size-3 flex-shrink-0" />
+      <span className="truncate">{label}</span>
+    </>
+  );
+
+  const base = cn(
+    "flex items-center gap-1.5 text-xs overflow-hidden min-w-0",
+    className,
+  );
+
+  if (href) {
+    return (
+      <a
+        href={href}
+        target="_blank"
+        rel="noopener noreferrer"
+        className={cn(
+          base,
+          "text-muted-foreground underline decoration-dotted hover:text-foreground transition-colors",
+        )}
+      >
+        {content}
+      </a>
+    );
+  }
+
+  return <span className={cn(base, "text-muted-foreground")}>{content}</span>;
+}
+
+/**
+ * Block-level external identifier display — icon + label in a card-like container.
+ * Used in detail renderers.
+ */
+export function ExternalIdentifierBlock({
+  value,
+  kType,
+  hint,
+  className,
+}: {
+  value: string;
+  kType?: string;
+  hint?: string;
+  className?: string;
+}) {
+  const type = kType || inferExternalIdentifierType(value);
+  const Icon = getExternalIdentifierIcon(type);
+  const label = getExternalIdentifierLabel(value, type);
+  const href = getExternalIdentifierHref(value, hint);
+
+  const inner = (
+    <div
+      className={cn(
+        "flex items-center gap-2 p-3 rounded-md bg-muted/50",
+        className,
+      )}
+    >
+      <Icon className="size-4 text-muted-foreground flex-shrink-0" />
+      <span className="text-sm break-all">{label}</span>
+    </div>
+  );
+
+  if (href) {
+    return (
+      <a
+        href={href}
+        target="_blank"
+        rel="noopener noreferrer"
+        className="hover:opacity-80 transition-opacity"
+      >
+        {inner}
+      </a>
+    );
+  }
+
+  return inner;
+}
diff --git a/src/components/nostr/kinds/Kind1111Renderer.tsx b/src/components/nostr/kinds/Kind1111Renderer.tsx
index 27a2a3e..3fba028 100644
--- a/src/components/nostr/kinds/Kind1111Renderer.tsx
+++ b/src/components/nostr/kinds/Kind1111Renderer.tsx
@@ -9,7 +9,7 @@ import {
 } from "applesauce-common/helpers/comment";
 import { useNostrEvent } from "@/hooks/useNostrEvent";
 import { UserName } from "../UserName";
-import { ExternalLink, Reply } from "lucide-react";
+import { Reply } from "lucide-react";
 import { useGrimoire } from "@/core/state";
 import { InlineReplySkeleton } from "@/components/ui/skeleton";
 import { KindBadge } from "@/components/KindBadge";
@@ -18,10 +18,10 @@ import type { NostrEvent } from "@/types/nostr";
 import {
   getCommentRootScope,
   isTopLevelComment,
-  getExternalIdentifierLabel,
   type CommentRootScope,
   type CommentScope,
 } from "@/lib/nip22-helpers";
+import { ExternalIdentifierInline } from "../ExternalIdentifierDisplay";
 
 /**
  * Convert CommentPointer to pointer format for useNostrEvent
@@ -149,21 +149,14 @@ function RootScopeDisplay({
   const pointer = scopeToPointer(root.scope);
   const rootEvent = useNostrEvent(pointer, event);
 
-  // External identifier (I-tag) — render as a link
+  // External identifier (I-tag) — render using shared NIP-73 component
   if (root.scope.type === "external") {
-    const { value, hint } = root.scope;
-    const label = getExternalIdentifierLabel(value, root.kind);
-    // Use hint if available, otherwise use value directly when it's a URL
-    const href =
-      hint ||
-      (value.startsWith("http://") || value.startsWith("https://")
-        ? value
-        : undefined);
     return (
-      <ScopeRow href={href}>
-        <ExternalLink className="size-3 flex-shrink-0" />
-        <span className="truncate">{label}</span>
-      </ScopeRow>
+      <ExternalIdentifierInline
+        value={root.scope.value}
+        kType={root.kind}
+        hint={root.scope.hint}
+      />
     );
   }
 
diff --git a/src/components/nostr/kinds/TrustedAssertionDetailRenderer.tsx b/src/components/nostr/kinds/TrustedAssertionDetailRenderer.tsx
index 490afb1..aa4dc77 100644
--- a/src/components/nostr/kinds/TrustedAssertionDetailRenderer.tsx
+++ b/src/components/nostr/kinds/TrustedAssertionDetailRenderer.tsx
@@ -1,5 +1,6 @@
 import { NostrEvent } from "@/types/nostr";
 import { UserName } from "../UserName";
+import { ExternalIdentifierBlock } from "../ExternalIdentifierDisplay";
 import {
   getAssertionSubject,
   getAssertionTags,
@@ -11,7 +12,7 @@ import {
   ASSERTION_TAG_LABELS,
 } from "@/lib/nip85-helpers";
 import { formatTimestamp } from "@/hooks/useLocale";
-import { BarChart3, User, FileText, Link, Hash } from "lucide-react";
+import { BarChart3, User, FileText, Hash } from "lucide-react";
 
 /**
  * Rank visualization bar
@@ -54,12 +55,22 @@ function MetricRow({
 /**
  * Subject header section based on kind
  */
-function SubjectHeader({ kind, subject }: { kind: number; subject: string }) {
+function SubjectHeader({
+  event,
+  subject,
+}: {
+  event: NostrEvent;
+  subject: string;
+}) {
+  // Kind 30385: NIP-73 external identifier — use shared block component
+  if (event.kind === 30385) {
+    const kTypes = getExternalAssertionTypes(event);
+    return <ExternalIdentifierBlock value={subject} kType={kTypes[0]} />;
+  }
+
   const icon =
-    kind === 30382 ? (
+    event.kind === 30382 ? (
       <User className="size-4" />
-    ) : kind === 30385 ? (
-      <Link className="size-4" />
     ) : (
       <FileText className="size-4" />
     );
@@ -67,7 +78,7 @@ function SubjectHeader({ kind, subject }: { kind: number; subject: string }) {
   return (
     <div className="flex items-center gap-2 p-3 rounded-md bg-muted/50">
       <span className="text-muted-foreground">{icon}</span>
-      {kind === 30382 ? (
+      {event.kind === 30382 ? (
         <UserName pubkey={subject} className="font-medium" />
       ) : (
         <span className="font-mono text-sm break-all">{subject}</span>
@@ -323,7 +334,7 @@ export function TrustedAssertionDetailRenderer({
       </div>
 
       {/* Subject */}
-      {subject && <SubjectHeader kind={event.kind} subject={subject} />}
+      {subject && <SubjectHeader event={event} subject={subject} />}
 
       {/* Rank */}
       {rankTag && (
diff --git a/src/components/nostr/kinds/TrustedAssertionRenderer.tsx b/src/components/nostr/kinds/TrustedAssertionRenderer.tsx
index d62aa9e..7e07b94 100644
--- a/src/components/nostr/kinds/TrustedAssertionRenderer.tsx
+++ b/src/components/nostr/kinds/TrustedAssertionRenderer.tsx
@@ -4,12 +4,14 @@ import {
   ClickableEventTitle,
 } from "./BaseEventRenderer";
 import { UserName } from "../UserName";
+import { ExternalIdentifierInline } from "../ExternalIdentifierDisplay";
 import {
   getAssertionSubject,
   getAssertionTags,
   getUserAssertionData,
   getEventAssertionData,
   getExternalAssertionData,
+  getExternalAssertionTypes,
   ASSERTION_KIND_LABELS,
   ASSERTION_TAG_LABELS,
 } from "@/lib/nip85-helpers";
@@ -19,18 +21,30 @@ import { BarChart3 } from "lucide-react";
  * Subject display based on assertion kind
  */
 function AssertionSubject({
-  kind,
+  event,
   subject,
 }: {
-  kind: number;
+  event: BaseEventProps["event"];
   subject: string;
 }) {
-  if (kind === 30382) {
+  if (event.kind === 30382) {
     // User: show as UserName
     return <UserName pubkey={subject} className="text-sm font-medium" />;
   }
 
-  if (kind === 30384) {
+  if (event.kind === 30385) {
+    // NIP-73 external identifier: use shared component with proper icon
+    const kTypes = getExternalAssertionTypes(event);
+    return (
+      <ExternalIdentifierInline
+        value={subject}
+        kType={kTypes[0]}
+        className="text-sm"
+      />
+    );
+  }
+
+  if (event.kind === 30384) {
     // Addressable event: kind:pubkey:d-tag
     const parts = subject.split(":");
     if (parts.length >= 3) {
@@ -42,10 +56,10 @@ function AssertionSubject({
     }
   }
 
-  // Event ID (30383) or NIP-73 identifier (30385)
+  // Event ID (30383) or fallback
   return (
     <span className="text-sm font-mono text-muted-foreground truncate">
-      {kind === 30383 ? `${subject.slice(0, 16)}...` : subject}
+      {subject.slice(0, 16)}...
     </span>
   );
 }
@@ -186,7 +200,7 @@ export function TrustedAssertionRenderer({ event }: BaseEventProps) {
         {subject && (
           <div className="flex items-center gap-1.5 text-sm">
             <span className="text-muted-foreground">Subject:</span>
-            <AssertionSubject kind={event.kind} subject={subject} />
+            <AssertionSubject event={event} subject={subject} />
           </div>
         )}
 
diff --git a/src/lib/nip22-helpers.ts b/src/lib/nip22-helpers.ts
index a1dacbc..7e0ad76 100644
--- a/src/lib/nip22-helpers.ts
+++ b/src/lib/nip22-helpers.ts
@@ -10,19 +10,12 @@ import type {
   AddressPointer,
   ProfilePointer,
 } from "nostr-tools/nip19";
-import type { LucideIcon } from "lucide-react";
-import {
-  Globe,
-  Podcast,
-  BookOpen,
-  FileText,
-  MapPin,
-  Hash,
-  Coins,
-  Film,
-  Flag,
-  ExternalLink,
-} from "lucide-react";
+
+// Re-export NIP-73 helpers for backwards compatibility
+export {
+  getExternalIdentifierIcon,
+  getExternalIdentifierLabel,
+} from "./nip73-helpers";
 
 // --- Types ---
 
@@ -174,71 +167,3 @@ export function isTopLevelComment(event: NostrEvent): boolean {
     return parent.kind !== "1111";
   });
 }
-
-/**
- * Map a NIP-73 external identifier type (K/k value) to an appropriate icon.
- */
-export function getExternalIdentifierIcon(kValue: string): LucideIcon {
-  if (kValue === "web") return Globe;
-  if (kValue.startsWith("podcast")) return Podcast;
-  if (kValue === "isbn") return BookOpen;
-  if (kValue === "doi") return FileText;
-  if (kValue === "geo") return MapPin;
-  if (kValue === "iso3166") return Flag;
-  if (kValue === "#") return Hash;
-  if (kValue === "isan") return Film;
-  // Blockchain types: "bitcoin:tx", "ethereum:1:address", etc.
-  if (kValue.includes(":tx") || kValue.includes(":address")) return Coins;
-  return ExternalLink;
-}
-
-/**
- * Get a human-friendly label for an external identifier value.
- */
-export function getExternalIdentifierLabel(
-  iValue: string,
-  kValue?: string,
-): string {
-  // URLs - show truncated
-  if (
-    kValue === "web" ||
-    iValue.startsWith("http://") ||
-    iValue.startsWith("https://")
-  ) {
-    try {
-      const url = new URL(iValue);
-      const path = url.pathname === "/" ? "" : url.pathname;
-      return `${url.hostname}${path}`;
-    } catch {
-      return iValue;
-    }
-  }
-
-  // Podcast types
-  if (iValue.startsWith("podcast:item:guid:")) return "Podcast Episode";
-  if (iValue.startsWith("podcast:publisher:guid:")) return "Podcast Publisher";
-  if (iValue.startsWith("podcast:guid:")) return "Podcast Feed";
-
-  // ISBN
-  if (iValue.startsWith("isbn:")) return `ISBN ${iValue.slice(5)}`;
-
-  // DOI
-  if (iValue.startsWith("doi:")) return `DOI ${iValue.slice(4)}`;
-
-  // Geohash
-  if (kValue === "geo") return `Location ${iValue}`;
-
-  // Country codes
-  if (kValue === "iso3166") return iValue.toUpperCase();
-
-  // Hashtag
-  if (iValue.startsWith("#")) return iValue;
-
-  // Blockchain
-  if (iValue.includes(":tx:"))
-    return `Transaction ${iValue.split(":tx:")[1]?.slice(0, 12)}...`;
-  if (iValue.includes(":address:"))
-    return `Address ${iValue.split(":address:")[1]?.slice(0, 12)}...`;
-
-  return iValue;
-}
diff --git a/src/lib/nip73-helpers.ts b/src/lib/nip73-helpers.ts
new file mode 100644
index 0000000..90ded41
--- /dev/null
+++ b/src/lib/nip73-helpers.ts
@@ -0,0 +1,138 @@
+/**
+ * NIP-73 External Content IDs
+ * Utility functions for parsing and displaying NIP-73 external identifiers
+ *
+ * External identifiers (i-tags) reference content outside Nostr:
+ * URLs, books (ISBN), podcasts, movies (ISAN), papers (DOI), geohashes,
+ * countries (ISO-3166), hashtags, and blockchain transactions/addresses.
+ *
+ * Used by:
+ * - NIP-22 comments (kind 1111) referencing external content
+ * - NIP-85 trusted assertions (kind 30385) rating external content
+ */
+
+import type { LucideIcon } from "lucide-react";
+import {
+  Globe,
+  Podcast,
+  BookOpen,
+  FileText,
+  MapPin,
+  Hash,
+  Coins,
+  Film,
+  Flag,
+  ExternalLink,
+} from "lucide-react";
+
+/**
+ * Map a NIP-73 external identifier type (K/k value) to an appropriate icon.
+ */
+export function getExternalIdentifierIcon(kValue: string): LucideIcon {
+  if (kValue === "web") return Globe;
+  if (kValue.startsWith("podcast")) return Podcast;
+  if (kValue === "isbn") return BookOpen;
+  if (kValue === "doi") return FileText;
+  if (kValue === "geo") return MapPin;
+  if (kValue === "iso3166") return Flag;
+  if (kValue === "#") return Hash;
+  if (kValue === "isan") return Film;
+  // Blockchain types: "bitcoin:tx", "ethereum:1:address", etc.
+  if (kValue.includes(":tx") || kValue.includes(":address")) return Coins;
+  return ExternalLink;
+}
+
+/**
+ * Get a human-friendly label for an external identifier value.
+ */
+export function getExternalIdentifierLabel(
+  iValue: string,
+  kValue?: string,
+): string {
+  // URLs - show truncated
+  if (
+    kValue === "web" ||
+    iValue.startsWith("http://") ||
+    iValue.startsWith("https://")
+  ) {
+    try {
+      const url = new URL(iValue);
+      const path = url.pathname === "/" ? "" : url.pathname;
+      return `${url.hostname}${path}`;
+    } catch {
+      return iValue;
+    }
+  }
+
+  // Podcast types
+  if (iValue.startsWith("podcast:item:guid:")) return "Podcast Episode";
+  if (iValue.startsWith("podcast:publisher:guid:")) return "Podcast Publisher";
+  if (iValue.startsWith("podcast:guid:")) return "Podcast Feed";
+
+  // ISBN
+  if (iValue.startsWith("isbn:")) return `ISBN ${iValue.slice(5)}`;
+
+  // DOI
+  if (iValue.startsWith("doi:")) return `DOI ${iValue.slice(4)}`;
+
+  // Geohash
+  if (kValue === "geo") return `Location ${iValue}`;
+
+  // Country codes
+  if (kValue === "iso3166") return iValue.toUpperCase();
+
+  // Hashtag
+  if (iValue.startsWith("#")) return iValue;
+
+  // Blockchain
+  if (iValue.includes(":tx:"))
+    return `Transaction ${iValue.split(":tx:")[1]?.slice(0, 12)}...`;
+  if (iValue.includes(":address:"))
+    return `Address ${iValue.split(":address:")[1]?.slice(0, 12)}...`;
+
+  return iValue;
+}
+
+/**
+ * Infer a NIP-73 k-tag value from an i-tag value when no k-tag is present.
+ * Useful for contexts where only the identifier is available.
+ */
+export function inferExternalIdentifierType(iValue: string): string {
+  if (iValue.startsWith("http://") || iValue.startsWith("https://"))
+    return "web";
+  if (iValue.startsWith("podcast:")) {
+    if (iValue.startsWith("podcast:item:guid:")) return "podcast:item:guid";
+    if (iValue.startsWith("podcast:publisher:guid:"))
+      return "podcast:publisher:guid";
+    return "podcast:guid";
+  }
+  if (iValue.startsWith("isbn:")) return "isbn";
+  if (iValue.startsWith("doi:")) return "doi";
+  if (iValue.startsWith("geo:")) return "geo";
+  if (iValue.startsWith("iso3166:")) return "iso3166";
+  if (iValue.startsWith("#")) return "#";
+  if (iValue.startsWith("isan:")) return "isan";
+  if (iValue.includes(":tx:")) {
+    const chain = iValue.split(":")[0];
+    return `${chain}:tx`;
+  }
+  if (iValue.includes(":address:")) {
+    const chain = iValue.split(":")[0];
+    return `${chain}:address`;
+  }
+  return "web";
+}
+
+/**
+ * Resolve the best href for an external identifier.
+ * Uses the hint if available, otherwise the raw value if it's a URL.
+ */
+export function getExternalIdentifierHref(
+  iValue: string,
+  hint?: string,
+): string | undefined {
+  if (hint) return hint;
+  if (iValue.startsWith("http://") || iValue.startsWith("https://"))
+    return iValue;
+  return undefined;
+}