# Router Request Cancellation Propagation

## Module
Router

## Status
IMPLEMENTED

## Description
CANCEL frame type for explicit request cancellation, inflight request tracking, client disconnect detection with automatic cancellation propagation to microservices, and CancellationToken integration in endpoint handlers.

## Implementation Details
- **Modules**: `src/Router/__Libraries/StellaOps.Router.Common/`, `src/Router/__Libraries/StellaOps.Microservice/`
- **Key Classes**:
  - `RequestDispatcher` (`src/Router/__Libraries/StellaOps.Microservice/RequestDispatcher.cs`) - tracks inflight requests and propagates cancellation tokens
  - `PathMatcher` (`src/Router/__Libraries/StellaOps.Router.Common/PathMatcher.cs`) - used in dispatch pipeline with cancellation support
- **Frame Types**: CANCEL frame for explicit request cancellation
- **Source**: batch_52/file_00.md

## E2E Test Plan
- [ ] Send a CANCEL frame for an inflight request and verify the endpoint handler's CancellationToken is triggered
- [ ] Disconnect a client during a long-running request and verify automatic cancellation propagation
- [ ] Verify inflight request tracking: confirm the dispatcher tracks active requests and cleans up after cancellation
- [ ] Verify endpoint handlers receive CancellationToken and can respond to cancellation gracefully
- [ ] Verify cancellation of a non-existent request ID is handled without errors