v0.9.4

What's New in v0.9.4

Uniform Declarative Schema System

• DeclarativeMetaclass — shared metaclass for all schema types with Annotated type hint introspection
• 6 schema types: StateSchema, ToolSchema, CallbackSchema, PredicateSchema, PromptSchema, MiddlewareSchema
• 5 annotation types: Reads, Writes, Param, Confirms, Timeout
• PredicateSchema is callable — works directly with Route.when() and S.guard()
• Contract checker Pass 13 validates schema reads_keys against upstream availability
• Contract checker Pass 14 validates scoped middleware schemas at target agent position

Middleware v2: Mechanism-Level Redesign

• TraceContext — per-invocation state bag flowing through all middleware hooks
• Per-agent scoping — agents class attribute with string, tuple, regex, or callable matching
• Topology hooks — on_loop_iteration, on_fanout_start/complete, on_route_selected, on_fallback_attempt, on_timeout
• Controllable dispatch — DispatchDirective(cancel=True) to skip dispatch tasks
• Error boundary — middleware exceptions caught, logged, and reported via on_middleware_error
• Stream lifecycle — on_stream_start, on_stream_end, on_backpressure
• Built-in middleware — TopologyLogMiddleware, LatencyMiddleware, CostTracker

M Module — Fluent Middleware Composition

• M class — consistent with P, C, S composition surfaces
• | operator — M.retry(3) | M.log() | M.topology_log()
• M.scope() — restrict middleware to specific agents
• M.when() — conditional middleware with string shortcuts, callables, or PredicateSchema
• Single-hook shortcuts — M.before_agent(), M.on_loop(), M.on_route(), etc.

MiddlewareSchema — Typed State Declarations for Middleware

• MiddlewareSchema class with Reads/Writes annotations
• schema class attribute on middleware (parallel to agents)
• Deferred evaluation in _ConditionalMiddleware — guarded async wrappers instead of early None
• M.when(PredicateSchema) — state-aware conditional middleware

Dispatch/Join/Stream Primitives

• dispatch() and join() extracted as standalone primitive builders
• StreamRunner for callback-driven execution with configurable concurrency
• Source and Inbox for stream input management
• Execution mode tracking via get_execution_mode()

P Namespace — Composable Prompt System

• P.system(), P.template(), P.conditional() — frozen, composable prompt transforms
• .when() conditionality unified across P, C, S modules

Engineering

• Composable S transforms — S.rename(), S.pick(), S.merge(), S.compute(), S.guard()
• Copy-on-write frozen builders — thread-safe builder reuse
• Rich .explain() output with data flow visualization
• 85 commits since v0.9.3, 2062 tests passing