diff --git a/frontend/src/styles/agent-mark.test.ts b/frontend/src/styles/agent-mark.test.ts
new file mode 100644
index 0000000..c01949e
--- /dev/null
+++ b/frontend/src/styles/agent-mark.test.ts
@@ -0,0 +1,87 @@
+/**
+ * Guards the Agent marks on the environment overview.
+ *
+ * The overview shows the mark on a transparent box, so unlike every other place
+ * a mark appears there is no chip tint and no border separating it from the
+ * card -- the glyph itself is the only thing carrying contrast. That makes two
+ * things load-bearing, neither of which any other gate covers:
+ *
+ *   - the box stays transparent, and
+ *   - --agent-mark-fg is full black on light and full white on dark.
+ *
+ * jsdom does not resolve var(), so getComputedStyle cannot see any of this; the
+ * assertions read the stylesheets as text instead. The CLI and desktop rules are
+ * checked together because they must agree: a row styled one way and its
+ * neighbour the other would read as two different kinds of object.
+ */
+import { readFileSync } from "node:fs";
+import { fileURLToPath } from "node:url";
+
+import { describe, expect, it } from "vitest";
+
+/** Comments carry `--token` names and `:` in prose, so they must go first. */
+function sheet(name: string): string {
+  const css = readFileSync(fileURLToPath(new URL(name, import.meta.url)), "utf8");
+  return css.replace(/\/\*[\s\S]*?\*\//g, " ");
+}
+
+/**
+ * The declarations of the last block whose prelude, with whitespace collapsed,
+ * is exactly `selector`. Last rather than first because a later block at equal
+ * specificity is what actually applies.
+ */
+function declarations(css: string, selector: string): Map<string, string> {
+  const want = selector.replace(/\s+/g, " ").trim();
+  const found = new Map<string, string>();
+  let seen = false;
+  for (const block of css.matchAll(/([^{}]+)\{([^{}]*)\}/g)) {
+    if (block[1].replace(/\s+/g, " ").trim() !== want) continue;
+    seen = true;
+    found.clear();
+    for (const part of block[2].split(";")) {
+      const split = part.indexOf(":");
+      if (split < 0) continue;
+      found.set(part.slice(0, split).trim(), part.slice(split + 1).trim().replace(/\s+/g, " "));
+    }
+  }
+  expect(seen, `${selector} should exist`).toBe(true);
+  return found;
+}
+
+const OVERVIEW_MARK_BOXES = [".agent-manage-identity .agent-icon", ".desktop-app-icon"];
+
+describe("overview Agent marks", () => {
+  it("paints the mark on a transparent box in both card types", () => {
+    const app = sheet("app.css");
+    for (const selector of OVERVIEW_MARK_BOXES) {
+      const rules = declarations(app, selector);
+      expect(rules.get("background"), selector).toBe("transparent");
+      expect(rules.get("color"), selector).toBe("var(--agent-mark-fg)");
+      // Neutralised, not removed: dropping the border would hand its 2px to the
+      // glyph, because .agent-icon sizes the 34px box as border-box.
+      expect(rules.get("border") ?? rules.get("border-color"), selector).toContain("transparent");
+      expect(rules.get("width"), selector).toBe("34px");
+      expect(rules.get("height"), selector).toBe("34px");
+    }
+  });
+
+  it("resolves the mark to black on light and white on dark", () => {
+    // The dark palette is declared twice in tokens.css -- once for the media
+    // query, once for .theme-dark -- and both copies must carry the override or
+    // forcing a theme would fall back to the light value.
+    const tokens = sheet("tokens.css");
+    expect(declarations(tokens, ":root").get("--agent-mark-fg")).toBe("#000000");
+    for (const selector of [":root:not(.theme-light)", ":root.theme-dark"]) {
+      expect(declarations(tokens, selector).get("--agent-mark-fg"), selector).toBe("#ffffff");
+    }
+  });
+
+  it("keeps the tinted chip for marks outside the overview", () => {
+    // .agent-icon is shared with the onboarding Agent list, which does want a
+    // bordered chip. Only the two overview rules opt out, so a change that
+    // flattened the base rule instead would be caught here.
+    const base = declarations(sheet("app.css"), ".agent-icon, .choice-icon, .progress-icon");
+    expect(base.get("background")).toBe("var(--surface-subtle)");
+    expect(base.get("color")).toBe("var(--icon-fg)");
+  });
+});
diff --git a/frontend/src/styles/app.css b/frontend/src/styles/app.css
index 3384dbb..77ab678 100644
--- a/frontend/src/styles/app.css
+++ b/frontend/src/styles/app.css
@@ -1089,13 +1089,19 @@
   gap: 9px;
 }
 
+/* The mark sits directly on the card: no chip, no tint. The border and
+   background from .agent-icon are neutralised rather than dropped, so the 34px
+   box keeps its geometry (border-box would otherwise hand the extra 2px to the
+   glyph). Colour comes from --agent-mark-fg, which is black or white per theme
+   -- on a transparent box the mark is the only thing carrying contrast, and
+   --icon-fg was mixed for a tinted chip. */
 .agent-manage-identity .agent-icon {
   width: 34px;
   height: 34px;
   border-radius: 8px;
-  border-color: color-mix(in srgb, var(--agent-accent) 24%, var(--border));
-  background: var(--agent-soft);
-  color: var(--agent-accent);
+  border-color: transparent;
+  background: transparent;
+  color: var(--agent-mark-fg);
 }
 
 .agent-manage-identity-copy {
@@ -1336,15 +1342,18 @@
   gap: 3px;
 }
 
+/* Matches .agent-manage-identity .agent-icon above: transparent box, mark in
+   black or white. The two must stay in step or the CLI and desktop Agents in
+   the same overview would read as different kinds of object. */
 .desktop-app-icon {
   width: 34px;
   height: 34px;
   display: grid;
   place-items: center;
-  border: 1px solid color-mix(in srgb, var(--agent-accent) 24%, var(--border));
+  border: 1px solid transparent;
   border-radius: 8px;
-  color: var(--agent-accent);
-  background: var(--agent-soft);
+  color: var(--agent-mark-fg);
+  background: transparent;
 }
 
 .desktop-app-identity strong { font-size: 16px; line-height: 1.3; }
diff --git a/frontend/src/styles/tokens.css b/frontend/src/styles/tokens.css
index 4c035db..49e523a 100644
--- a/frontend/src/styles/tokens.css
+++ b/frontend/src/styles/tokens.css
@@ -16,6 +16,11 @@
   --border-faint: rgba(60, 60, 67, 0.08);
   --icon-border: rgba(60, 60, 67, 0.12);
   --icon-fg: #3a3a3c;
+  /* Full black/white rather than --icon-fg, and only for the Agent marks on the
+     overview. They sit on a transparent box there, so nothing tints them and
+     nothing separates them from the card -- the mark itself has to carry the
+     contrast. Elsewhere the marks stay on --icon-fg inside a bordered chip. */
+  --agent-mark-fg: #000000;
   --footer-bg: rgba(250, 250, 251, 0.96);
   --overlay-panel: rgba(255, 255, 255, 0.7);
   --blue: #007aff;
@@ -64,6 +69,7 @@
     --border-faint: rgba(255, 255, 255, 0.08);
     --icon-border: rgba(255, 255, 255, 0.12);
     --icon-fg: #d1d1d6;
+    --agent-mark-fg: #ffffff;
     --footer-bg: rgba(28, 28, 30, 0.96);
     --overlay-panel: rgba(0, 0, 0, 0.25);
     --blue: #0a84ff;
@@ -96,6 +102,7 @@
     --border-faint: rgba(255, 255, 255, 0.08);
     --icon-border: rgba(255, 255, 255, 0.12);
     --icon-fg: #d1d1d6;
+    --agent-mark-fg: #ffffff;
     --footer-bg: rgba(28, 28, 30, 0.96);
     --overlay-panel: rgba(0, 0, 0, 0.25);
     --blue: #0a84ff;