feat(sdk-compatibility): Add SDK Compatibility SKILL. (#33)

Author: pedropobla

revenuecat/skills/revenuecat-sdk-compatibility/SKILL.md

@@ -0,0 +1,51 @@
+---
+name: revenuecat-sdk-compatibility
+description: Check whether an SDK version supports a RevenueCat feature, whether an SDK upgrade is required, why an SDK-gated feature is not working, or how much of a project's recent subscriber base is on incompatible SDK versions. Use for questions about RevenueCat SDK compatibility, feature gates, minimum SDK versions, SDK adoption, upgrade impact, and rollout risk.
+---
+
+# RevenueCat SDK compatibility
+
+Use the RevenueCat MCP server for all tool calls here.
+
+## Check feature compatibility
+
+Call `list-sdk-feature-gates` before making any SDK compatibility claim. Find the gate that matches
+the user's feature and use its minimum version for each relevant RevenueCat SDK.
+
+- If the relevant feature gate cannot be identified, say so and explain which gates looked close
+  instead of guessing. Consult the docs linked in the tool output to disambiguate.
+- When more than one gate could apply, prefer the most specific gate. For example:
+  - Existing-customer experiment enrollment: `experiment-existing-customer-enrollment`
+  - Experiment exposure status or reporting: `experiment-exposure-tracking`
+  - New-customer experiment enrollment: `experiment-new-customer-enrollment`
+- If multiple gates jointly matter, evaluate and name each one.
+
+## Analyze SDK adoption
+
+Call `list-sdk-versions` to assess upgrade impact or rollout risk from SDK versions observed in the
+project. Each row describes subscribers seen in the last 30 days and includes:
+
+- `sdk_type`: RevenueCat SDK family.
+- `sdk_version`: underlying native SDK version for native rows, or the native SDK bundled under a
+  wrapper in `platform_flavor` rows.
+- `sortable_sdk_version`: normalized value for ordering `sdk_version`.
+- `platform`: native platform, such as `ios` or `android`, when grouped by platform or platform
+  flavor.
+- `platform_flavor` and `platform_flavor_version`: wrapper SDK family and version, such as
+  `react-native` `10.0.1`, when grouped by platform flavor.
+- `subscribers_last_30days` and `pct_of_subscribers`: recent project usage counts and shares.
+
+Choose the grouping that matches the question:
+
+- Use `sdk_type` for a high-level inventory by RevenueCat SDK family.
+- Use `platform` to compare native iOS and Android adoption.
+- Use `platform_flavor` for React Native, Flutter, Capacitor, Unity, Kotlin Multiplatform, and other
+  wrappers where both the wrapper version and bundled native SDK versions matter.
+
+To compute upgrade impact, filter to the relevant SDK family, compare observed versions with the
+feature gate's `min_version`, and sum `subscribers_last_30days` and `pct_of_subscribers` for rows
+below the requirement. State that these figures represent subscribers observed in the last 30 days,
+not the all-time install base.
+
+Use `jq` for quick filtering or a code execution tool for version comparisons, grouping, and
+subscriber-share calculations when the output is too large to analyze reliably by inspection.