diff --git a/Initial Plan.md b/Initial Plan.md
index e59f641..3040e24 100644
--- a/Initial Plan.md	
+++ b/Initial Plan.md	
@@ -436,7 +436,7 @@ Advanced JavaScript or TypeScript adapters should be clearly marked and reviewed
 ### Phase 1 — First useful version
 
 * [x] Clean reading mode
-* [ ] OP highlighting
+* [x] OP highlighting
 * [ ] New posts since last visit
 * [ ] Save comments
 * [ ] Local user notes
diff --git a/ROADMAP.md b/ROADMAP.md
index 9bca008..15094b2 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -8,8 +8,10 @@ features before the adapter ecosystem, AI last and always optional.
 > **Status:** Phase 0 complete; Phase 1 underway. The foundation — core post
 > model, generic extractor, local storage layer — and the `apps/extension` MV3
 > shell (background, on-demand content script, side panel) are built, unit-tested,
-> and bundled via esbuild. Phase 1 has begun with **clean reading mode**: the side
-> panel now renders each post's rich `contentHtml` through an allowlist sanitizer.
+> and bundled via esbuild. Phase 1 has begun with **clean reading mode** (the side
+> panel renders each post's rich `contentHtml` through an allowlist sanitizer) and
+> **OP highlighting** (OP / mod / admin posts get a readable badge and a colored
+> edge so the important voices stand out across the thread).
 
 ## Phase 0 — Foundation
 
@@ -23,7 +25,7 @@ features before the adapter ecosystem, AI last and always optional.
 ## Phase 1 — First useful version
 
 - [x] Clean reading mode — sanitized rich `contentHtml` rendering in the side panel (`apps/extension`)
-- [ ] OP highlighting
+- [x] OP highlighting — OP / mod / admin posts get a readable badge and a colored edge in the side panel (`apps/extension`)
 - [ ] New posts since last visit
 - [ ] Save comments
 - [ ] Local user notes
diff --git a/apps/extension/README.md b/apps/extension/README.md
index f8dd45d..c665fa0 100644
--- a/apps/extension/README.md
+++ b/apps/extension/README.md
@@ -2,8 +2,9 @@
 
 The ForumForge **browser extension** — a Manifest V3 app that turns the thread on
 the current page into a clean, readable list in a side panel. It is the Phase 0
-shell that later features (clean reading mode, OP highlighting, notes, saved
-posts) build on.
+shell that later features (notes, saved posts, new-post tracking) build on, and
+it already ships the first Phase 1 reading features — clean reading mode and OP
+highlighting.
 
 It wires together the foundation packages: the active page's DOM →
 [`@forumforge/parser`](../../packages/parser) → the
@@ -28,6 +29,10 @@ side panel "Read this thread" ─▶ inject content.js (activeTab) ─▶ extrac
 - **`src/render.ts`** — builds the read-only view. Author, role and timestamp are
   written with `textContent`; the body renders the post's rich `contentHtml`
   through the sanitizer (clean reading mode), falling back to plain text.
+  **OP highlighting:** OP / moderator / admin posts get a readable role badge and
+  a colored edge (driven by a `data-role` attribute and styled in
+  `public/sidepanel.html`); the role is set by the parser and follows the OP
+  through the whole thread. The plain "user" role is left unmarked.
 - **`src/sanitize.ts`** — the **clean reading mode** sanitizer. Untrusted post
   HTML is parsed inertly and rebuilt from an allowlist of safe, semantic tags and
   attributes, so no script, inline handler, style, embed or unsafe URL survives
diff --git a/apps/extension/public/sidepanel.html b/apps/extension/public/sidepanel.html
index 0063f1a..5701e1e 100644
--- a/apps/extension/public/sidepanel.html
+++ b/apps/extension/public/sidepanel.html
@@ -46,6 +46,27 @@
         padding: 10px 0;
         border-top: 1px solid #8883;
       }
+      /* OP highlighting: posts by an important voice stand out for the whole
+         thread, with a colored edge and a faint tint (not color alone — the
+         badge text carries the same signal). */
+      .ff-post[data-role="op"],
+      .ff-post[data-role="mod"],
+      .ff-post[data-role="admin"] {
+        border-left: 3px solid #8884;
+        padding-left: 10px;
+      }
+      .ff-post[data-role="op"] {
+        border-left-color: #2563eb;
+        background: #2563eb14;
+      }
+      .ff-post[data-role="mod"] {
+        border-left-color: #16a34a;
+        background: #16a34a14;
+      }
+      .ff-post[data-role="admin"] {
+        border-left-color: #9333ea;
+        background: #9333ea14;
+      }
       .ff-post__meta {
         display: flex;
         gap: 8px;
@@ -57,12 +78,25 @@
       }
       .ff-post__role {
         font-size: 11px;
-        text-transform: uppercase;
         letter-spacing: 0.04em;
         padding: 1px 6px;
         border-radius: 999px;
         background: #8882;
       }
+      .ff-post[data-role="op"] .ff-post__role {
+        background: #2563eb;
+        color: #fff;
+      }
+      .ff-post[data-role="mod"] .ff-post__role {
+        /* Darker green than the edge so white badge text clears WCAG AA
+           contrast (~5:1) — the badge text is the non-color role signal. */
+        background: #15803d;
+        color: #fff;
+      }
+      .ff-post[data-role="admin"] .ff-post__role {
+        background: #9333ea;
+        color: #fff;
+      }
       .ff-post__time {
         color: #888;
         font-size: 12px;
diff --git a/apps/extension/src/render.ts b/apps/extension/src/render.ts
index b1c98c3..2b9fe75 100644
--- a/apps/extension/src/render.ts
+++ b/apps/extension/src/render.ts
@@ -1,7 +1,18 @@
-import type { ForumForgePost } from "@forumforge/core";
+import type { ForumForgePost, ForumRole } from "@forumforge/core";
 import type { ExtractedThread } from "@forumforge/parser";
 import { sanitizeHtml } from "./sanitize";
 
+/**
+ * Human-readable badge text per role. The OP highlighting feature surfaces who
+ * is who in a thread; "user" is the unmarked default, so it gets no badge.
+ */
+const ROLE_LABELS: Record<ForumRole, string> = {
+  op: "OP",
+  mod: "Mod",
+  admin: "Admin",
+  user: "",
+};
+
 /**
  * Build a clean, read-only view of an extracted thread.
  *
@@ -53,10 +64,11 @@ function renderPost(doc: Document, post: ForumForgePost, baseUrl?: string): HTML
   author.textContent = post.author;
   meta.append(author);
 
-  if (post.role) {
+  const roleLabel = post.role ? ROLE_LABELS[post.role] : "";
+  if (roleLabel) {
     const role = doc.createElement("span");
     role.className = "ff-post__role";
-    role.textContent = post.role;
+    role.textContent = roleLabel;
     meta.append(role);
   }
 
diff --git a/apps/extension/test/render.test.ts b/apps/extension/test/render.test.ts
index 024817b..fdf33a5 100644
--- a/apps/extension/test/render.test.ts
+++ b/apps/extension/test/render.test.ts
@@ -22,10 +22,25 @@ describe("renderThread", () => {
     expect(view.querySelector(".ff-thread__title")?.textContent).toBe("Monitor no signal");
     expect(view.querySelectorAll(".ff-post")).toHaveLength(2);
     expect(view.querySelector(".ff-post__author")?.textContent).toBe("ada");
-    expect(view.querySelector(".ff-post__role")?.textContent).toBe("op");
+    expect(view.querySelector(".ff-post__role")?.textContent).toBe("OP");
     expect(view.querySelector(".ff-post[data-role='op']")).not.toBeNull();
   });
 
+  it("shows a readable badge for highlighted roles but none for plain users", () => {
+    const thread: ExtractedThread = {
+      posts: [
+        { id: "1", author: "ada", role: "mod", contentText: "Moved to the right forum." },
+        { id: "2", author: "grace", role: "user", contentText: "Thanks." },
+      ],
+    };
+    const view = renderThread(freshDocument(), thread);
+    const badges = view.querySelectorAll(".ff-post__role");
+
+    // The moderator post is the only one with a badge; "user" is the unmarked default.
+    expect(Array.from(badges).map((b) => b.textContent)).toEqual(["Mod"]);
+    expect(view.querySelector(".ff-post[data-role='mod']")).not.toBeNull();
+  });
+
   it("shows an empty state when there are no posts", () => {
     const view = renderThread(freshDocument(), { posts: [] });
     expect(view.querySelector(".ff-empty")?.textContent).toBe("No posts found on this page.");