feat(tcp-connector): add Embassy TCP listener pool (#171)

Implement the Embassy TCP server as an explicit N-socket pool backed by
caller-owned RX/TX buffers and make the Embassy TCP dialer reusable across
disconnects/redials.

Also tighten `tcp://` endpoint validation for IPv6 targets, clean up TCP connector
feature dependencies and include the tokio KNX demo in fmt-check coverage.

Author: thaodt

Cargo.lock

@@ -187,7 +187,7 @@ fmt:
 fmt-check:
 	@printf "$(GREEN)Checking code formatting (workspace members only)...$(NC)\n"
 	@FAILED=0; \
-	for pkg in aimdb-derive aimdb-data-contracts aimdb-core aimdb-client aimdb-embassy-adapter aimdb-tokio-adapter aimdb-wasm-adapter aimdb-sync aimdb-persistence aimdb-persistence-sqlite aimdb-mqtt-connector aimdb-knx-connector aimdb-ws-protocol aimdb-websocket-connector aimdb-uds-connector aimdb-serial-connector aimdb-tcp-connector aimdb-codegen aimdb-cli aimdb-mcp sync-api-demo tokio-mqtt-connector-demo embassy-mqtt-connector-demo embassy-knx-connector-demo embassy-serial-connector-demo embassy-bench-stm32h5 weather-mesh-common weather-hub weather-station-alpha weather-station-beta hello-mailbox hello-mailbox-async hello-single-latest-async aimdb-bench; do \
+	for pkg in aimdb-derive aimdb-data-contracts aimdb-core aimdb-client aimdb-embassy-adapter aimdb-tokio-adapter aimdb-wasm-adapter aimdb-sync aimdb-persistence aimdb-persistence-sqlite aimdb-mqtt-connector aimdb-knx-connector aimdb-ws-protocol aimdb-websocket-connector aimdb-uds-connector aimdb-serial-connector aimdb-tcp-connector aimdb-codegen aimdb-cli aimdb-mcp sync-api-demo tokio-mqtt-connector-demo embassy-mqtt-connector-demo tokio-knx-connector-demo embassy-knx-connector-demo embassy-serial-connector-demo embassy-bench-stm32h5 weather-mesh-common weather-hub weather-station-alpha weather-station-beta hello-mailbox hello-mailbox-async hello-single-latest-async aimdb-bench; do \
 		printf "$(YELLOW)  → Checking $$pkg$(NC)\n"; \
 		if ! cargo fmt -p $$pkg -- --check 2>&1; then \
 			printf "$(RED)❌ Formatting check failed for $$pkg$(NC)\n"; \

Makefile

@@ -207,7 +207,7 @@ See the [MCP server docs](tools/aimdb-mcp/) for Claude Desktop and other editors
 | **MQTT** — `aimdb-mqtt-connector` | ✅ Ready | std, no_std |
 | **KNX** — `aimdb-knx-connector` | ✅ Ready | std, no_std |
 | **WebSocket** — `aimdb-websocket-connector` | ✅ Ready | std, wasm |
-| **TCP** — `aimdb-tcp-connector` | ✅ Ready | std, no_std client |
+| **TCP** — `aimdb-tcp-connector` | ✅ Ready | std, no_std |
 | **Kafka** | 📋 Planned | std |
 | **Modbus** | 📋 Planned | std, no_std |
 

README.md

@@ -170,12 +170,42 @@ fn require_nonempty(endpoint: &str, target: &str) -> ClientResult<()> {
 fn require_tcp_target(endpoint: &str, target: &str) -> ClientResult<()> {
     require_nonempty(endpoint, target)?;
 
-    let Some((host, port)) = target.rsplit_once(':') else {
-        return Err(ClientError::unsupported_endpoint(
-            endpoint,
-            "missing TCP port",
-        ));
+    let (host, port) = if let Some(rest) = target.strip_prefix('[') {
+        let Some((host, after_host)) = rest.split_once(']') else {
+            return Err(ClientError::unsupported_endpoint(
+                endpoint,
+                "missing closing bracket for IPv6 TCP host",
+            ));
+        };
+        let Some(port) = after_host.strip_prefix(':') else {
+            return Err(ClientError::unsupported_endpoint(
+                endpoint,
+                "missing TCP port",
+            ));
+        };
+        (host, port)
+    } else {
+        if target.matches(':').count() > 1 {
+            return Err(ClientError::unsupported_endpoint(
+                endpoint,
+                "IPv6 TCP hosts must be bracketed, e.g. tcp://[::1]:7001",
+            ));
+        }
+        let Some((host, port)) = target.split_once(':') else {
+            return Err(ClientError::unsupported_endpoint(
+                endpoint,
+                "missing TCP port",
+            ));
+        };
+        if host.contains(['[', ']']) {
+            return Err(ClientError::unsupported_endpoint(
+                endpoint,
+                "malformed TCP host",
+            ));
+        }
+        (host, port)
     };
+
     if host.is_empty() {
         return Err(ClientError::unsupported_endpoint(
             endpoint,
@@ -268,6 +298,14 @@ mod tests {
         let p = parse_endpoint("tcp://localhost:7001").expect("parse");
         assert_eq!(p.scheme, Scheme::Tcp);
         assert_eq!(p.target, "localhost:7001");
+
+        let p = parse_endpoint("tcp://[::1]:7001").expect("parse");
+        assert_eq!(p.scheme, Scheme::Tcp);
+        assert_eq!(p.target, "[::1]:7001");
+
+        let p = parse_endpoint("tcp://[fe80::1]:7001").expect("parse");
+        assert_eq!(p.scheme, Scheme::Tcp);
+        assert_eq!(p.target, "[fe80::1]:7001");
     }
 
     #[test]
@@ -277,6 +315,10 @@ mod tests {
         assert!(parse_endpoint("tcp://host").is_err());
         assert!(parse_endpoint("tcp://:1234").is_err());
         assert!(parse_endpoint("tcp://host:fast").is_err());
+        assert!(parse_endpoint("tcp://fe80::1").is_err());
+        assert!(parse_endpoint("tcp://[fe80::1]").is_err());
+        assert!(parse_endpoint("tcp://[]:7001").is_err());
+        assert!(parse_endpoint("tcp://[fe80::1:7001").is_err());
         // Empty + empty target.
         assert!(parse_endpoint("").is_err());
         assert!(parse_endpoint("unix://").is_err());

aimdb-client/src/endpoint.rs

@@ -17,7 +17,6 @@ std = [
     "aimdb-core/alloc",
     "aimdb-core/connector-session",
     "aimdb-core/remote",
-    "thiserror",
 ]
 
 tokio-runtime = [
@@ -38,26 +37,22 @@ embassy-runtime = [
     "dep:embedded-io-async",
 ]
 
-tracing = ["dep:tracing", "aimdb-core/tracing"]
-defmt = ["dep:defmt", "aimdb-core/defmt"]
+tracing = ["aimdb-core/tracing"]
+defmt = ["aimdb-core/defmt"]
 
 _test-tokio = ["tokio-runtime", "dep:aimdb-tokio-adapter"]
 
 [dependencies]
 aimdb-core = { version = "1.1.0", path = "../aimdb-core", default-features = false }
 
 tokio = { workspace = true, optional = true, features = ["net", "io-util"] }
-thiserror = { workspace = true, optional = true }
 
 aimdb-embassy-adapter = { version = "0.6.0", path = "../aimdb-embassy-adapter", default-features = false, optional = true }
 embassy-net = { workspace = true, optional = true }
 embedded-io-async = { workspace = true, optional = true }
 
 aimdb-tokio-adapter = { version = "0.6.0", path = "../aimdb-tokio-adapter", optional = true }
 
-tracing = { workspace = true, optional = true }
-defmt = { workspace = true, optional = true }
-
 [dev-dependencies]
 tokio = { version = "1", features = ["rt-multi-thread", "macros", "time", "io-util", "net"] }
 serde = { workspace = true }