Understanding Hot Reload Limits: stay inside the fast path

Android Runtime (ART) enforces strict rules for class redefinition: a redefined class must have an identical schema (fields, method signatures, interfaces) as the previous version. Only method bodies are mutable at runtime. HotSwan automatically detects schema changes and falls back to a full incremental build, so failures are not silent. Knowing the boundary in advance is what keeps an iteration loop sub-second instead of multi-second.

When to use this skill

• The developer asks "why did this trigger a full rebuild?", "why isn't this hot reloading?", or " what does HotSwan support?".
• A PR review surfaces a refactor (parameter change, constructor change, interface extraction, new resource id) that would push a hot-reload session into a rebuild.
• The developer is planning a session and wants to order edits so the slow ones happen at the end.
• The developer reports an inline fun change that "didn't reload" and is debugging.

When NOT to use this skill