| name | asupersync-mega-skill |
| description | Replace Tokio Rust stacks with Asupersync. Use when migrating tokio/axum/hyper/tonic apps, designing native Cx/region-based services, or debugging Asupersync internals. |
Asupersync Mega Skill
Asupersync is a spec-first, cancel-correct, capability-secure async runtime for Rust. Not a Tokio wrapper -- a complete replacement with stronger guarantees around structured concurrency, obligation tracking, deterministic testing, and capability security.
This skill is primarily for agents integrating Asupersync into other projects or extracting maximum architectural leverage from it in greenfield systems. It also covers repo-internal work when that is the actual task.
For codebase orientation, types, module map, and workspace layout see SOURCE-MAP.md.
Quick Orient
Minimal bootstrap:
use asupersync::runtime::RuntimeBuilder;
fn main() -> Result<(), asupersync::Error> {
let rt = RuntimeBuilder::current_thread().build()?;
rt.block_on(async {
let cx = asupersync::Cx::for_request();
asupersync::proc_macros::scope!(cx, {
cx.trace("running");
asupersync::Outcome::ok(())
});
});
Ok(())
}
This is the smallest runnable seam, not the recommended production architecture. Do not build serious services around Cx::for_request() plus block_on(...) alone; prefer runtime-managed contexts, request/call regions at service boundaries, and graduate to AppSpec + supervision when the topology becomes long-lived.
Where to focus first:
- Lead with core runtime,
Cx/Scope, cancellation, obligations, channels, sync, time, lab/DPOR, and observability
- For ordinary services, build next on native
service, web, grpc, database, and supervision surfaces
- Treat Browser Edition, QUIC/H3, messaging, remote/distributed, and RaptorQ as requirement-driven lanes, not default starting points
Default recommendation order for most real projects:
- core runtime +
Cx + Scope
- native
service / web / grpc boundaries
- native database and actor/supervision surfaces as needed
- deterministic tests and diagnostics from the start
Do not lead with Browser Edition, QUIC/H3, messaging, remote/distributed, or RaptorQ unless the target project explicitly needs those capabilities.
Full surface guidance: STACK-SURFACES.md.
Start Here
Choose one lane before touching code:
- Native greenfield
Build directly on
RuntimeBuilder, Cx, Scope, LabRuntime, and optional AppSpec.
- Brownfield native migration
Rewrite your app's async seams around
&Cx, region-owned tasks, cancel-aware primitives, and deterministic tests.
- Boundary interop
Use
asupersync-tokio-compat only for crates you cannot remove yet. Keep Tokio out of core business logic.
Default rule:
- prefer native Asupersync surfaces,
- use compat only as a quarantine boundary,
- plan to remove compat once the stubborn dependency is gone.
Non-Negotiables
- Do not treat Asupersync as an executor swap.
- Put
&Cx first in async APIs you control.
- Use
Scope and child regions for owned work. Avoid detached background tasks.
- Add
cx.checkpoint() in loops, retry bodies, long handlers, and shutdown-sensitive code.
- Prefer cancel-aware primitives and two-phase effects.
- Use deterministic tests as part of normal development, not as optional polish.
- Treat
Cx::for_testing() as test-only. Cx::for_request() is a convenience seam, not your whole architecture.
- Keep Tokio and Tokio-only crates behind explicit adapter modules if you must keep them at all.
Leverage, Not Just Migration
If the target system is doing real work, do not stop after "the code compiles on Asupersync."
Canonical Spine
- Bootstrap:
runtime::RuntimeBuilder, Runtime, RuntimeHandle
- App code:
Cx, Scope
- Tests:
test_utils::{run_test, run_test_with_cx}, LabRuntime, LabConfig
- Service boundaries:
web::request_region::{RequestRegion, RequestContext}, grpc::CallContext::with_cx(...)
- Higher-level apps:
app::AppSpec, actor, gen_server, supervision, spork
Start with RuntimeBuilder + Cx + Scope. Graduate to AppSpec + supervision when you need restart policy, named workers, or explicit application topology.
Macro guidance: scope! is useful. Manual APIs are still the safest authoritative path. Do not assume proc-macro surfaces are automatically the best default path for every task.
Standard Workflow
- Inventory all
tokio::*, tokio-util, hyper, axum, tonic, reqwest, sqlx, quinn, h3, rdkafka, and related dependencies.
- Classify each dependency as: native replacement, compat holdout, or deliberate workaround.
- Replace runtime bootstrap first.
- Thread
&Cx through your own async APIs.
- Replace detached spawning with region-owned work.
- Replace sync/time/net/io/channel/web/db/messaging surfaces domain by domain.
- Add deterministic tests while migrating, not after.
- Remove compat boundaries as soon as the underlying dependency no longer needs them.
Reference Index
Quick Router: Start Here For Your Task
All References
Integration and Migration
Architecture and Primitives
Networking and Services
Testing and Diagnostics
Codebase Navigation
Validation
When changing code:
- run the host project's normal formatter, compiler, lint, and test suite,
- add deterministic integration tests for the migrated path,
- verify cancellation, shutdown, and resource-release behavior,
- verify that no core domain code still depends on Tokio if the goal is full native adoption.
If working inside the Asupersync repo itself, see REPO-CONTRIBUTOR-GUIDE.md for mandatory compiler checks and testing discipline.
Operating Rules
- When forced to choose between "minimal code churn" and "native Asupersync semantics", choose the latter unless the task explicitly calls for a temporary boundary bridge.
- Forbidden crates in core:
tokio, hyper, reqwest, axum, async-std, smol.
- Inside the Asupersync repo: follow AGENTS.md. Never delete files without permission. Branch is
main, never master.
