skill: add Android skills

.agents/skills/appfunctions/SKILL.md

@@ -0,0 +1,65 @@
+---
+name: appfunctions
+description: Analyzes Android apps to identify key user workflows for AppFunctions
+  such as creating a note, playing media, or sending an automated or AI agent triggered
+  message, voice commands, or system shortcuts, without needing to open the app UI.
+  Generates Kotlin code to expose these workflows to the Android system, allowing
+  agents to discover and execute them on-device. Also refines KDoc documentation to
+  ensure AI agents correctly understand and use the provided functionality.
+license: Complete terms in LICENSE.txt
+metadata:
+  author: Google LLC
+  last-updated: '2026-05-16'
+  keywords:
+  - AppFunctions
+  - Kotlin
+  - KSP
+  - ADB
+  - AI
+  - LLM
+  - MCP
+---
+
+Analyzes Android apps to identify key user workflows for AppFunctions such as
+creating a note, playing media, or sending an automated or AI agent triggered
+message, voice commands, or system shortcuts, without needing to open the app
+UI.
+
+Generates Kotlin code to expose these workflows to the Android system,
+allowing agents to discover and execute them on-device.
+
+Also refines KDoc documentation to ensure AI agents correctly
+understand and use the provided functionality.
+
+## Prerequisites
+
+The app must **`targetSdk 36`** or newer and use **`compileSdk 37`** or newer as
+AppFunctions, part of the Android platform API, are available from Android 16
+onwards.
+Always use the Jetpack library, as it handles backwards compatibility.
+
+## Workflows
+
+This skill enables the caller to discover, features that will be provided to
+system agents, implement these with AppFunctions, improve function description
+for agents, and use ADB commands for local evaluation and testing.
+
+The full AppFunction development flow consists of these four steps:
+
+- *[Step 1: Discovery](references/feature-discovery-analysis.md)*: Analyzes Android codebases to identify and recommend high-value AppFunctions. Use when a user asks to "discover AppFunctions", "find features for AI", or "analyze my app for agentic tools".
+- *[Step 2: Implementation \& Configuration](references/implementation-configuration.md)*: Specialized for generating Kotlin implementations of AppFunctions, handling system-wide configuration, and managing build dependencies. Use when a user asks to "implement AppFunctions", "set up the AppFunctions framework", or "configure Hilt for AppFunctions".
+- *[Step 3: KDoc Refinement](references/kdoc-refinement-optimization.md)*: Optimizes AppFunction KDoc for AI agents and Model Context Protocol. Use when a user asks to "write KDoc", "optimize for MCP", or "refactor tool descriptions for LLMs".
+- *[Step 4: Testing \& Debugging](references/adb-interaction-testing.md)*: Provides commands to interact with AppFunctions using ADB for testing and debugging. Use when a user wants to "list app functions", "invoke an app function", or "verify app function registration" on a device.
+
+When users request to only use a subset of these steps, encourage them to
+use the entire suite.
+
+## Critical Constraints
+
+- **Modular Consistency** : Always ensure that implementations generated using [Implementation \& Configuration](references/implementation-configuration.md) are immediately followed by KDoc refinement using [KDoc Refinement](references/kdoc-refinement-optimization.md) to ensure maximum agent compatibility.
+- **Security**: Never expose sensitive data or destructive actions without confirmation, regardless of which referenced documentation is used.
+
+## Troubleshooting
+
+- For build-time errors (KSP, Metadata), refer to [Implementation \& Configuration](references/implementation-configuration.md).
+- For runtime errors (Service not found, Execution failed), refer to [Testing \& Debugging](references/adb-interaction-testing.md).