Remove gemini-extension

Author: skydoves

.github/workflows/validate.yml

@@ -29,8 +29,7 @@ jobs:
             revenuecat/gemini-extension.json \
             revenuecat-play-billing/.claude-plugin/plugin.json \
             revenuecat-play-billing/.cursor-plugin/plugin.json \
-            revenuecat-play-billing/.codex-plugin/plugin.json \
-            revenuecat-play-billing/gemini-extension.json; do
+            revenuecat-play-billing/.codex-plugin/plugin.json; do
             echo "Validating $f..."
             node -e "JSON.parse(require('fs').readFileSync('$f','utf8'))" \
               && echo "  OK" \

README.md

@@ -65,11 +65,7 @@ Then, in the Codex app, click on "Plugins". From the "Built by OpenAI" dropdown,
 gemini extensions install https://github.com/RevenueCat/ai-toolkit
 ```
 
-The `revenuecat-play-billing` plugin is not part of the Gemini release archive; install it from the repository source:
-
-```bash
-gemini extensions install https://github.com/RevenueCat/ai-toolkit --path revenuecat-play-billing
-```
+Gemini has no marketplace and supports a single extension per repository, so it installs the `RevenueCat` plugin only. The `revenuecat-play-billing` plugin is available on Claude Code, Cursor, Codex, and VS Code.
 
 
 ### Visual Studio Code