diff --git a/.changeset/fix-cli-weak-span-dark-terminal.md b/.changeset/fix-cli-weak-span-dark-terminal.md
new file mode 100644
index 00000000000..d3cbe86d02a
--- /dev/null
+++ b/.changeset/fix-cli-weak-span-dark-terminal.md
@@ -0,0 +1,5 @@
+---
+"@effect/cli": patch
+---
+
+Fix `@effect/cli` help output to use `Ansi.blackBright` instead of `Ansi.black` for `Weak` spans. The previous black foreground was invisible on dark terminal backgrounds.
diff --git a/packages/cli/src/internal/helpDoc/span.ts b/packages/cli/src/internal/helpDoc/span.ts
index 249ea311654..c41251c9fd1 100644
--- a/packages/cli/src/internal/helpDoc/span.ts
+++ b/packages/cli/src/internal/helpDoc/span.ts
@@ -139,7 +139,7 @@ export const toAnsiDoc = (self: Span.Span): Doc.AnsiDoc => {
       return Doc.annotate(Doc.text(self.value), Ansi.underlined)
     }
     case "Weak": {
-      return Doc.annotate(toAnsiDoc(self.value), Ansi.black)
+      return Doc.annotate(toAnsiDoc(self.value), Ansi.blackBright)
     }
   }
 }
diff --git a/packages/cli/test/HelpDoc.test.ts b/packages/cli/test/HelpDoc.test.ts
new file mode 100644
index 00000000000..34c6ad44222
--- /dev/null
+++ b/packages/cli/test/HelpDoc.test.ts
@@ -0,0 +1,17 @@
+import * as HelpDoc from "@effect/cli/HelpDoc"
+import * as Span from "@effect/cli/HelpDoc/Span"
+import * as AnsiDoc from "@effect/printer-ansi/AnsiDoc"
+import { describe, expect, it } from "@effect/vitest"
+
+describe("HelpDoc", () => {
+  describe("toAnsiDoc", () => {
+    it("Weak spans use bright black (dark gray), not black, so they are readable on dark terminals", () => {
+      const span = Span.weak("name")
+      const ansiDoc = HelpDoc.toAnsiDoc(HelpDoc.p(span))
+      const rendered = AnsiDoc.render(ansiDoc, { style: "pretty" })
+      // ANSI foreground code 30 = black — invisible on dark/black terminal backgrounds.
+      // Weak spans must not produce this code.
+      expect(rendered).not.toMatch(/\x1b\[[0-9;]*30[;m]/)
+    })
+  })
+})