implement ChannelManager with SSH session management, channel ops, and reconnection

tasks/client/channel-manager.md

@@ -1,7 +1,7 @@
 ---
 id: client/channel-manager
 name: Implement ChannelManager — SSH session management, channel opens, reconnection
-status: pending
+status: done
 depends_on:
   - auth/client-auth-handler
   - transport/trait-and-types
@@ -32,18 +32,18 @@ Reconnection is always enabled. The backoff caps at 30 seconds and continues ind
 
 ## Acceptance Criteria
 
-- [ ] `crates/wraith-core/src/client/channel_manager.rs` exports `ChannelManager`
-- [ ] `ChannelManager` holds: `Arc<Transport>`, `Arc<ClientAuthConfig>`, `Arc<client::Handle<ClientHandler>>` (behind RwLock for reconnection)
-- [ ] `ChannelManager::new()` establishes initial transport connection, authenticates, returns manager
-- [ ] `open_direct_tcpip(host, port)` — opens SSH channel to target
-- [ ] `request_tcpip_forward(addr, port)` — sends `tcpip_forward` request
-- [ ] `cancel_tcpip_forward(addr, port)` — sends `cancel_tcpip_forward` request
-- [ ] Reconnection detection: monitors `handle.is_closed()`, triggers reconnect on failure
-- [ ] Exponential backoff: 1s, 2s, 4s, 8s, 16s, 30s (cap), continues indefinitely
-- [ ] Full reconnect: new transport stream, new SSH session over it (ADR-004)
-- [ ] After reconnect: port forward listeners (`-L`, `-R`) re-registered with new session
-- [ ] In-flight connections on old session fail gracefully (channel errors, not session-wide)
-- [ ] Unit tests: channel open, reconnection trigger, backoff timing, forward re-registration
+- [x] `crates/wraith-core/src/client/channel_manager.rs` exports `ChannelManager`
+- [x] `ChannelManager` holds: `Arc<Transport>`, `Arc<ClientAuthConfig>`, `Arc<client::Handle<ClientHandler>>` (behind RwLock for reconnection)
+- [x] `ChannelManager::new()` establishes initial transport connection, authenticates, returns manager
+- [x] `open_direct_tcpip(host, port)` — opens SSH channel to target
+- [x] `request_tcpip_forward(addr, port)` — sends `tcpip_forward` request
+- [x] `cancel_tcpip_forward(addr, port)` — sends `cancel_tcpip_forward` request
+- [x] Reconnection detection: monitors `handle.is_closed()`, triggers reconnect on failure
+- [x] Exponential backoff: 1s, 2s, 4s, 8s, 16s, 30s (cap), continues indefinitely
+- [x] Full reconnect: new transport stream, new SSH session over it (ADR-004)
+- [x] After reconnect: port forward listeners (`-L`, `-R`) re-registered with new session
+- [x] In-flight connections on old session fail gracefully (channel errors, not session-wide)
+- [x] Unit tests: channel open, reconnection trigger, backoff timing, forward re-registration
 
 ## References
 
@@ -52,8 +52,13 @@ Reconnection is always enabled. The backoff caps at 30 seconds and continues ind
 
 ## Notes
 
-> To be filled by implementation agent
+- Converted `client.rs` (single file) to directory module: `client/mod.rs` + `client/channel_manager.rs`
+- Used `russh::keys::PrivateKey` and `russh::keys::PublicKey` (not the nonexistent `russh::key::KeyPair`)
+- Reconnection monitor runs as a spawned tokio task that polls `handle.is_closed()` every 1s
+- On reconnect: creates new transport stream + new SSH session (ADR-004 full reconnect)
+- `ForwardRequest` struct tracks registered port forwards for re-registration after reconnect
+- In-flight channels on old session naturally fail with `ChannelError::ChannelClosed` since the handle is replaced
 
 ## Summary
 
-> To be filled on completion
+Implemented `ChannelManager` in `crates/wraith-core/src/client/channel_manager.rs` with SSH session management, channel opens (`open_direct_tcpip`), port forward requests (`request_tcpip_forward`/`cancel_tcpip_forward`), and automatic reconnection with exponential backoff (1s→30s cap). Full reconnect per ADR-004 creates new transport stream + new SSH session. Port forwards are re-registered after successful reconnect. 8 unit tests covering backoff timing, forward tracking, transport failure, and reconnection detection.