Release 0.8.0

Added

Executor Enhancements

• Dual-timeout model — Global deadline enforcement (executor.global_timeout) alongside per-module timeout. The shorter of the two is applied, preventing nested call chains from exceeding the global budget.
• Cooperative cancellation — On module timeout, the executor sends CancelToken.cancel() and waits a 5-second grace period before raising ModuleTimeoutError. Modules that check cancel_token can clean up gracefully.
• Error propagation (Algorithm A11) — All execution paths (sync, async, stream) now wrap exceptions via propagate_error(), ensuring middleware always receives ModuleError instances with trace context.
• Deep merge for streaming — Streaming chunk accumulation uses recursive deep merge (depth-capped at 32) instead of shallow merge, correctly handling nested response structures.

Error System

• ErrorCodeRegistry — Custom module error codes are validated against framework prefixes and other modules to prevent collisions. Raises ErrorCodeCollisionError on conflict.
• VersionIncompatibleError — New error class for SDK/config version mismatches with negotiate_version() utility.
• MiddlewareChainError — Now explicitly _default_retryable = False per PROTOCOL_SPEC §8.6.

Utilities

• guard_call_chain() — Standalone Algorithm A20 implementation for call chain safety checks (depth, circular, frequency). Executor delegates to this utility.
• propagate_error() — Standalone Algorithm A11 implementation for error wrapping and trace context attachment.
• normalize_to_canonical_id() — Cross-language module ID normalization (Python snake_case, Go PascalCase, etc.).
• calculate_specificity() — ACL pattern specificity scoring for deterministic rule ordering.
• parse_docstring() — Docstring parser for extracting parameter descriptions from function docstrings.

ACL Enhancements

• Audit logging — ACL constructor accepts optional audit_logger callback. All access decisions emit AuditEntry with timestamp, caller/target IDs, matched rule, identity, and trace context.
• Condition-based rules — ACL rules support conditions for identity type, role, and call depth filtering.

Config System

• Full validation — Config.validate() checks schema structure, value types, and range constraints.
• Hot reload — Config.reload() re-reads the YAML source and re-validates.
• Environment overrides — APCORE_* environment variables override config values (e.g., APCORE_EXECUTOR_DEFAULT_TIMEOUT=5000).
• Config.from_defaults() — Factory method for default configuration.

Middleware

• RetryMiddleware — Configurable retry with exponential/fixed backoff, jitter, and max delay. Only retries errors marked retryable=True.

Registry Enhancements

• ID conflict detection — Registry detects and prevents registration of conflicting module IDs.
• Safe unregister — safe_unregister() with drain timeout for graceful module removal.

Context

• Generic services typing — Context[T] supports typed dependency injection via the services field.

Testing

• Conformance test suite — JSON fixture-driven tests for error codes, call chain safety, ACL evaluation, pattern matching, specificity, ID normalization, and version negotiation.
• New unit tests — 17 new test files covering all added features.

Changed

Executor Internals

• _check_safety() now delegates to standalone guard_call_chain() instead of inline logic.
• Error handling wraps exceptions with propagate_error() and re-raises with raise wrapped from exc.
• Global deadline set on root call only, propagated to child contexts via Context._global_deadline.

Public API

• Expanded __all__ in apcore.__init__ with new exports: RetryMiddleware, RetryConfig, ErrorCodeRegistry, ErrorCodeCollisionError, VersionIncompatibleError, negotiate_version, guard_call_chain, propagate_error, normalize_to_canonical_id, calculate_specificity, AuditEntry, parse_docstring.