ranger, learning-opportunities, and playground are declared as pi
packages and also present in the Claude plugin cache, so the bridge
injected each twice. Filtering against the skills pi already loaded,
exposed on before_agent_start, removes the duplicates.

Assisted-by: GLM-5.2 via pi

diff --git a/ai/pi/extensions/claude-plugins.ts b/ai/pi/extensions/claude-plugins.ts
index 11d475ba..67d44784 100644
--- a/ai/pi/extensions/claude-plugins.ts
+++ b/ai/pi/extensions/claude-plugins.ts
@@ -2,8 +2,9 @@
  * Claude Plugins Bridge
  *
  * Loads skills from Claude Code's plugin cache (~/.claude/plugins/cache)
- * and makes them available in pi. Claude's installed plugins become the
- * source of truth — no duplicate configuration needed.
+ * and makes them available in pi. When a skill is also provided by pi itself
+ * (skills/ directories or packages), the pi version wins and the Claude
+ * plugin copy is skipped so the prompt never carries duplicates.
  *
  * Structure expected:
  *   ~/.claude/plugins/cache/<marketplace>/<plugin>/<version>/
@@ -17,7 +18,7 @@
 import * as fs from "node:fs";
 import * as path from "node:path";
 import * as os from "node:os";
-import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";
+import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
 
 const CACHE_DIR = path.join(os.homedir(), ".claude", "plugins", "cache");
 
@@ -186,19 +187,38 @@ function safeReaddirEntries(dir: string): fs.Dirent[] {
 }
 
 export default function claudePlugins(pi: ExtensionAPI) {
-  let skills: PluginSkill[] = [];
+  // Raw skills discovered from the plugin cache this session.
+  let discovered: PluginSkill[] = [];
+  // Skills actually injected into the prompt, after deferring to pi's own.
+  // Null until computed on the first before_agent_start of the session.
+  let injected: PluginSkill[] | null = null;
+
+  pi.on("session_start", async () => {
+    discovered = discoverSkills();
+    injected = null;
+  });
+
+  pi.on("before_agent_start", async (event, ctx) => {
+    if (discovered.length === 0) return;
 
-  pi.on("session_start", async (_event, ctx) => {
-    skills = discoverSkills();
-    if (skills.length > 0) {
-      ctx.ui.notify(`Claude plugins: ${skills.length} skill(s) loaded`, "info");
+    // systemPromptOptions.skills is what pi already loaded from its own
+    // skills/ directories and packages. Those win over plugin-cache copies.
+    if (injected === null) {
+      const piNames = new Set(
+        (event.systemPromptOptions.skills ?? []).map((s) => s.name)
+      );
+      injected = discovered.filter((s) => !piNames.has(s.name));
+      const skipped = discovered.length - injected.length;
+      const msg =
+        skipped > 0
+          ? `Claude plugins: ${injected.length} skill(s) loaded, ${skipped} deferred to pi`
+          : `Claude plugins: ${injected.length} skill(s) loaded`;
+      ctx.ui.notify(msg, "info");
     }
-  });
 
-  pi.on("before_agent_start", async (event) => {
-    if (skills.length === 0) return;
+    if (injected.length === 0) return;
 
-    const xml = skills
+    const xml = injected
       .map(
         (s) =>
           `  <skill>\n    <name>${s.name}</name>\n    <description>${escapeXml(s.description)}</description>\n    <location>${s.path}</location>\n  </skill>`