Decompose architecture into 35 atomic tasks across 10 generations for implementation

tasks/transport/iroh-transport.md

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+---
+id: transport/iroh-transport
+name: Implement IrohTransport and IrohAcceptor (feature-gated iroh)
+status: pending
+depends_on:
+  - transport/trait-and-types
+  - transport/tcp-transport
+scope: moderate
+risk: high
+impact: component
+level: implementation
+---
+
+## Description
+
+Implement iroh QUIC P2P transport. Per ADR-003, use `tokio::io::join(recv_stream, send_stream)` to combine iroh's split QUIC streams into a single duplex stream that russh can consume.
+
+Client-side: `IrohTransport` connects to a remote iroh endpoint, opens a bidirectional QUIC stream, and joins the halves.
+Server-side: `IrohAcceptor` creates an iroh endpoint, accepts incoming connections, accepts bidirectional streams.
+
+iroh supports proxy configuration natively via `Endpoint::builder()`, which is how `--proxy` works with iroh transport (ADR-010).
+
+Feature-gated behind `iroh` feature flag.
+
+## Acceptance Criteria
+
+- [ ] `crates/wraith-core/src/transport/iroh.rs` (behind `#[cfg(feature = "iroh")]`)
+- [ ] `IrohTransport` holds: target endpoint ID (base58-decoded to `NodeId`), relay URL, optional proxy URL
+- [ ] `IrohTransport::connect()` calls `endpoint.connect(node_id, alpn)`, then `conn.open_bi()`, then `tokio::io::join(recv, send)`
+- [ ] ALPN value is `b"wraith-ssh"`
+- [ ] `IrohTransport::describe()` returns e.g. `"iroh://<endpoint-id>"`
+- [ ] `IrohAcceptor` holds an `iroh::Endpoint` instance
+- [ ] `IrohAcceptor::bind()` creates endpoint with relay URL and optional proxy config
+- [ ] `IrohAcceptor::accept()` calls `endpoint.accept()`, then `conn.accept_bi()`, then `tokio::io::join(recv, send)`
+- [ ] `IrohAcceptor` exposes `endpoint_id()` returning base58-encoded node ID for CLI display
+- [ ] Default relay is n0's `https://relay.iroh.network/` (ADR-009)
+- [ ] Proxy URL passed to `Endpoint::builder()` for outbound proxy (ADR-010)
+- [ ] `TransportInfo.transport_kind` is `TransportKind::Iroh { endpoint_id }`
+- [ ] Module re-exported from `transport/mod.rs` behind `#[cfg(feature = "iroh")]`
+- [ ] Unit tests: endpoint creation, stream join produces correct type
+- [ ] Integration test: iroh client connects to iroh server, stream is duplex (may need iroh relay, mark `#[ignore]` for CI)
+
+## References
+
+- docs/architecture/transport.md — IrohTransport row, iroh stream join, relay config
+- docs/architecture/decisions/003-iroh-stream-join.md — tokio::io::join rationale
+- docs/architecture/decisions/009-default-iroh-relay.md — default relay
+- docs/architecture/decisions/010-transport-chaining-cli.md — proxy configuration
+
+## Notes
+
+> To be filled by implementation agent
+
+## Summary
+
+> To be filled on completion