diff --git a/apps/gittensory-miner-extension/README.md b/apps/gittensory-miner-extension/README.md
index 02506e396..f287babd7 100644
--- a/apps/gittensory-miner-extension/README.md
+++ b/apps/gittensory-miner-extension/README.md
@@ -28,6 +28,13 @@ The extension does not request the `unlimitedStorage` permission, so a paste is
 being parsed or saved once it exceeds a conservative size bound well under `chrome.storage.local`'s default 10 MiB
 quota, instead of silently failing to save or leaving storage partially written.
 
+## Icons
+
+`icons/` holds the standard MV3 icon set (16/32/48/128) referenced from `manifest.json`'s top-level
+`icons` and `action.default_icon`. Regenerate with `node icons/generate-icons.mjs` after the underlying
+brand asset changes — it resizes `apps/gittensory-ui/public/favicon-512.png` via `sharp`, so the
+extension's icon is always the same mark as the main site's favicon rather than a separately drawn asset.
+
 ## Host permissions
 
 `manifest.json` grants `https://github.com/*` (for the issue-page content script) plus loopback host permissions —
diff --git a/apps/gittensory-miner-extension/icons/generate-icons.mjs b/apps/gittensory-miner-extension/icons/generate-icons.mjs
new file mode 100644
index 000000000..95b0bef75
--- /dev/null
+++ b/apps/gittensory-miner-extension/icons/generate-icons.mjs
@@ -0,0 +1,23 @@
+#!/usr/bin/env node
+// Regenerates the MV3 icon set (#4862) from the repo's own brand asset -- never hand-drawn/synthesized
+// geometry, so the extension's icon is always the same mark as apps/gittensory-ui's favicon. Standard
+// Chrome/Firefox MV3 sizes: 16 (toolbar/favicon), 32 (Windows/high-DPI toolbar), 48 (extensions page),
+// 128 (Chrome Web Store listing + install dialog).
+import { dirname, resolve } from "node:path";
+import { fileURLToPath } from "node:url";
+import sharp from "sharp";
+
+const here = dirname(fileURLToPath(import.meta.url));
+const sourceIcon = resolve(here, "../../gittensory-ui/public/favicon-512.png");
+const sizes = [16, 32, 48, 128];
+
+await Promise.all(
+  sizes.map((size) =>
+    sharp(sourceIcon)
+      .resize(size, size)
+      .png()
+      .toFile(resolve(here, `icon-${size}.png`)),
+  ),
+);
+
+console.log(`wrote icon-${sizes.join(".png, icon-")}.png from ${sourceIcon}`);
diff --git a/apps/gittensory-miner-extension/icons/icon-128.png b/apps/gittensory-miner-extension/icons/icon-128.png
new file mode 100644
index 000000000..a686f0700
Binary files /dev/null and b/apps/gittensory-miner-extension/icons/icon-128.png differ
diff --git a/apps/gittensory-miner-extension/icons/icon-16.png b/apps/gittensory-miner-extension/icons/icon-16.png
new file mode 100644
index 000000000..9913979ed
Binary files /dev/null and b/apps/gittensory-miner-extension/icons/icon-16.png differ
diff --git a/apps/gittensory-miner-extension/icons/icon-32.png b/apps/gittensory-miner-extension/icons/icon-32.png
new file mode 100644
index 000000000..1f9df7e1c
Binary files /dev/null and b/apps/gittensory-miner-extension/icons/icon-32.png differ
diff --git a/apps/gittensory-miner-extension/icons/icon-48.png b/apps/gittensory-miner-extension/icons/icon-48.png
new file mode 100644
index 000000000..15442aee5
Binary files /dev/null and b/apps/gittensory-miner-extension/icons/icon-48.png differ
diff --git a/apps/gittensory-miner-extension/manifest.json b/apps/gittensory-miner-extension/manifest.json
index f27558bd7..fe6fc4923 100644
--- a/apps/gittensory-miner-extension/manifest.json
+++ b/apps/gittensory-miner-extension/manifest.json
@@ -3,6 +3,12 @@
   "name": "LoopOver Miner Opportunity",
   "description": "Contributor-facing GitHub issue opportunity signals from a locally configured miner plane.",
   "version": "0.1.0",
+  "icons": {
+    "16": "icons/icon-16.png",
+    "32": "icons/icon-32.png",
+    "48": "icons/icon-48.png",
+    "128": "icons/icon-128.png"
+  },
   "permissions": ["storage"],
   "host_permissions": ["https://github.com/*", "http://localhost/*", "http://127.0.0.1/*"],
   "background": {
@@ -19,6 +25,12 @@
   ],
   "options_page": "options.html",
   "action": {
-    "default_title": "LoopOver Miner"
+    "default_title": "LoopOver Miner",
+    "default_icon": {
+      "16": "icons/icon-16.png",
+      "32": "icons/icon-32.png",
+      "48": "icons/icon-48.png",
+      "128": "icons/icon-128.png"
+    }
   }
 }
diff --git a/scripts/build-miner-extension.mjs b/scripts/build-miner-extension.mjs
index 67d4a4fd4..9d0fc7432 100644
--- a/scripts/build-miner-extension.mjs
+++ b/scripts/build-miner-extension.mjs
@@ -22,10 +22,15 @@ const PACKAGE_FILES = [
   "options.js",
   "styles.css",
   "toolbar-badge.js",
+  "icons/icon-16.png",
+  "icons/icon-32.png",
+  "icons/icon-48.png",
+  "icons/icon-128.png",
 ];
 
 rmSync(outDir, { recursive: true, force: true });
 mkdirSync(outDir, { recursive: true });
+mkdirSync(resolve(outDir, "icons"), { recursive: true });
 
 for (const file of PACKAGE_FILES) {
   cpSync(resolve(source, file), resolve(outDir, file));
diff --git a/test/unit/miner-extension-icons.test.ts b/test/unit/miner-extension-icons.test.ts
new file mode 100644
index 000000000..fa280c82b
--- /dev/null
+++ b/test/unit/miner-extension-icons.test.ts
@@ -0,0 +1,40 @@
+import { readFileSync } from "node:fs";
+import sharp from "sharp";
+import { describe, expect, it } from "vitest";
+
+const EXTENSION_DIR = "apps/gittensory-miner-extension";
+const ICON_SIZES = [16, 32, 48, 128];
+
+describe("miner extension icon set (#4862)", () => {
+  const manifest = JSON.parse(readFileSync(`${EXTENSION_DIR}/manifest.json`, "utf8"));
+
+  it("wires every icon size into the manifest's top-level icons and action.default_icon", () => {
+    for (const size of ICON_SIZES) {
+      const path = `icons/icon-${size}.png`;
+      expect(manifest.icons[String(size)]).toBe(path);
+      expect(manifest.action.default_icon[String(size)]).toBe(path);
+    }
+  });
+
+  it("ships a real PNG at the declared size for every icon", async () => {
+    for (const size of ICON_SIZES) {
+      const metadata = await sharp(`${EXTENSION_DIR}/icons/icon-${size}.png`).metadata();
+      expect(metadata.format).toBe("png");
+      expect(metadata.width).toBe(size);
+      expect(metadata.height).toBe(size);
+    }
+  });
+
+  it("packages every icon file into the built zip's PACKAGE_FILES list", () => {
+    const buildScript = readFileSync("scripts/build-miner-extension.mjs", "utf8");
+    for (const size of ICON_SIZES) {
+      expect(buildScript).toContain(`icons/icon-${size}.png`);
+    }
+  });
+
+  it("regenerates the icons from the repo's own brand asset, not a hand-drawn/synthesized source", () => {
+    const generator = readFileSync(`${EXTENSION_DIR}/icons/generate-icons.mjs`, "utf8");
+    expect(generator).toContain("favicon-512.png");
+    expect(generator).toContain("sharp");
+  });
+});