Aventa Extension Development Specification

# Package identity

Package id and semantic version form the package identity. Identity is immutable for one admitted candidate; upgrades publish a complete new candidate.

# Manifest rules

Manifests are closed declarations. Unknown, duplicate or invalid fields fail validation. Declared resources must exist and undeclared runtime edges are not allowed.

# Lifecycle, capability and dependency rules

Only legal lifecycle transitions publish. Capabilities are type-bounded and rechecked. Dependency ordering is deterministic; cycles fail closed.

# Data and migration rules

Every mutable namespace has one owner. Migration history is immutable and journaled. Cross-package private storage is forbidden.

# Typed event rules

Events are versioned and host-owned. Payloads and contributions are validated. Failure policy and ordering are explicit.

# Determinism and fail-closed behavior

Equivalent inputs must produce equivalent declarations, plans and product effects. Missing authority, ambiguity or invalid state stops the operation.

# Theme and presentation rules

Themes use typed presentation data and named composition. Enabled and effective are separate. Themes do not receive general business-storage authority.

# Public Kernel SDK boundary

Use documented public classes and scoped runtime services. Do not import Kernel internals, mutate registries directly or construct a second control plane.

# Package Status

DEVELOPMENT_PACKAGE is the normal starting state. A host may assign ENGINEERING_VALIDATED after its selected engineering suite passes. Higher reserved states are not part of normal development.

# Naming

Use stable lowercase package ids, semantic versions, versioned event names and package-owned namespace prefixes. Prefer explicit domain names over framework abbreviations.

# Forbidden Practices

• Kernel internal imports
• legacy Xiuno runtime calls
• cross-package private storage
• arbitrary filesystem overwrite
• self-promotion of assurance status
• silent dependency or capability fallback

# Compatibility Policy

Legacy Xiuno plugins are not directly supported. Migration into Aventa packages is required. Preserve business behavior, not unsafe integration edges.