{session-id {:abort-ids #{abort-id-1 abort-id-2 ...}
             :aborting? false}}

Tracks in-flight abort IDs per statechart session for Fulcro load cancellation.

The `tracker` is an atom whose shape is:

```
{session-id {:abort-ids #{abort-id-1 abort-id-2 ...}
             :aborting? false}}
```

All functions take the tracker atom as the first argument.

A composable statechart-driven UI routing system for Fulcro applications.

Provides statechart-based routing with deep busy-checking, cross-chart routing
via `:route/reachable`, and optional bidirectional URL synchronization.

Uses a well-known `session-id` constant for the routing statechart session,
keeping the public API simple. Parallel regions handle multiple independent
routing areas within a single chart.

Component options for statechart-driven routing.
Follows the RAD pattern: options ns = base API ns + '-options'.

ALPHA. This namespace's API is subject to change.

BrowserURLHistory — a URLHistoryProvider that wraps `js/window.history` with
monotonic index tracking. CLJS-only implementation; the namespace is CLJC so
it can be required unconditionally, but provides no CLJ implementation.

ALPHA. This namespace's API is subject to change.

SimulatedURLHistory — a cross-platform URLHistoryProvider backed by an atom.
Useful for headless testing of statechart-driven routing without a browser.

ALPHA. This namespace's API is subject to change.

URLCodec protocol and codec-agnostic functions that convert statechart
configuration into URLs. The protocol defines encode/decode; implementations
live in separate namespaces (e.g. `url-codec-transit` for the default
transit+base64 codec).

ALPHA. This namespace's API is subject to change.

Default URLCodec implementation using transit+base64 encoding.
URL shape: `/Seg1/Seg2?_p=<base64-encoded-transit>`.

ALPHA. This namespace's API is subject to change.

URLHistoryProvider protocol and shared URL utility functions for
statechart-driven routing. Implementations live in separate namespaces
for CLJS dead-code elimination:

- `browser-history` — BrowserURLHistory (CLJS-only, wraps js/window.history)
- `simulated-history` — SimulatedURLHistory (cross-platform, for testing)