Persistence & Crash Recovery

Append: Runtime saves a checkpoint after every successful step.

Crash: External state remains committed; process state is lost.

Resume: Restarted process loads trace and resumes from the last cursor.

PostgreSQL: ACID compliant, multi-process durable storage.

Redis: High-throughput, sub-millisecond ephemeral checkpoints.

InMemory: No dependencies, ideal for tests and local development.

Compensation: Define rollback hooks for irreversible side effects.

Idempotency: Ensure compensation runs exactly once per trace.

Auto-Trigger: Runtime kicks off hooks automatically on Fault.

Define typed decision flows with Axon/Transition/Outcome contracts, explicit Bus wiring, and `Never` error type for infallible pipelines. 61 maintained examples covering all 10 crates.

Run protocol-agnostic core circuits through HTTP ingress adapters with dynamic routing, request extractors, lifecycle controls, middleware composition, and per-path policy overrides.

Apply HTTP security/policy stacks with `ranvier-std` Guard nodes (CorsGuard, RateLimit, SecurityHeaders, IpFilter) — visible in Schematic and Inspector Timeline.

Generate OpenAPI docs and Swagger UI from request/response contracts via `ranvier-openapi`.

Serve static directories and SPA fallback with cache/compression options for fullstack-style delivery.

Handle WebSocket/SSE real-time flows and inject connection/session context into Bus.

Build LLM-as-Transition pipelines for AI classification, content moderation, and policy enforcement.

Write in-process HTTP integration tests with `TestApp/TestRequest/TestResponse` and runtime path assertions with `AxonTestKit`/`Timeline`.

Store and query traces with `ranvier-inspector` TraceStore, secure endpoints with BearerAuth, and route alerts via AlertHook/AlertDispatcher.

Run session/job/persistence patterns and resume faulted workflows from checkpoints with PersistenceStore and compensation hooks.

Validate API compatibility and detect structural drift with cargo-semver-checks and schematic diff/policy CLI commands.

Monitor per-node metrics (throughput, latency percentiles, error rate), inspect in-transit payloads, manage dead letters, set conditional breakpoints, and detect stalled nodes through the built-in Inspector REST + WebSocket server.

Register JSON Schema on circuit nodes via `.with_input_schema::<T>()` builder API or `#[transition(schema)]` macro attribute. Inspector serves schema-enriched route metadata (`GET /api/v1/routes`), relays HTTP requests into running circuits (`POST /api/v1/relay`), and generates empty templates or random sample payloads from schema (`POST /api/v1/routes/schema`, `POST /api/v1/routes/sample`).

Configure production infrastructure with `RanvierConfig` (`ranvier.toml` + env overrides + profile system), structured logging (`init_logging()` with JSON/pretty/compact), and optional TLS via `rustls`.

Return RFC 7807 Problem Details error responses with `ProblemDetail`/`IntoProblemDetail`, and retry faulted transitions with `RetryPolicy` (fixed/exponential backoff) via `Axon::then_with_retry()`.

Provide quantitative performance baselines with criterion micro-benchmarks (Axon latency, Bus operations, Transition chains) and Axum/Actix-web comparison servers.

Demonstrate real-world patterns through three reference applications: Todo API (CRUD + JWT auth), Chat Server (multi-room WebSocket), and E-commerce Order Pipeline (4-stage Saga compensation + audit trail + multi-tenancy).

Automate version migration with `ranvier migrate --from 0.20 --to 0.25` for import path replacement, crate dependency swaps. TOML-based migration rules (text_replace, rename_import, warn) with --dry-run mode.

Export Prometheus exposition metrics from Inspector `/metrics` endpoint, auto-initialize OTLP TracerProvider via TelemetryConfig, log HTTP requests with AccessLogGuard path redaction, persist audit events to PostgreSQL with PostgresAuditSink hash-chain integrity, and auto-register OpenAPI SecurityScheme (bearerAuth) with ProblemDetail (RFC 7807) error responses.

Understand framework design philosophy through PHILOSOPHY.md ('Opinionated Core, Flexible Edges' principle) and architecture decision rationale via DESIGN_PRINCIPLES.md (ADR format covering Paradigm Test, Tower Separation, and Opinionated Core enforcement).

Implement authentication using two approaches: Transition-based (examples/auth-transition — Bus context propagation, Schematic visualization, easier testing) or Tower integration (examples/auth-tower-integration — AsyncAuthorizeRequest trait for ecosystem compatibility).

Compare authentication strategies with docs/guides/auth-comparison.md: 7-feature comparison table, performance benchmarks (~1-2μs overhead both), when-to-use decision tree, and migration paths between Transition and Tower approaches.

Token/claim-to-role mapping for inspector auth headers is not built into core runtime and depends on deployment gateway policy.