major improvements for big apps

Source/Components/Interfaces/DebugService/DebugService.cpp

@@ -324,6 +324,8 @@ ErrorManagement::ErrorType DebugService::Server(ExecutionInfo &info) {
                                 if (out.Size() > 0u) {
                                     const char8 *wPtr = out.Buffer();
                                     uint32 remaining  = (uint32)out.Size();
+                                    lastDataTimeMs = (uint64)((float64)HighResolutionTimer::Counter() *
+                                                              HighResolutionTimer::Period() * 1000.0);
                                     while (remaining > 0u) {
                                         uint32 wrote = remaining;
                                         if (!activeClient->Write(wPtr, wrote) || wrote == 0u) {
@@ -331,6 +333,8 @@ ErrorManagement::ErrorType DebugService::Server(ExecutionInfo &info) {
                                         }
                                         wPtr      += wrote;
                                         remaining -= wrote;
+                                        lastDataTimeMs = (uint64)((float64)HighResolutionTimer::Counter() *
+                                                                  HighResolutionTimer::Period() * 1000.0);
                                     }
                                 }
                             }

Source/Components/Interfaces/DebugService/DebugService.h

@@ -94,7 +94,10 @@ private:
 
     // Rate-limiting and idle-timeout constants / state
     static const uint32 CMD_RATE_LIMIT        = 100u;
-    static const uint32 CLIENT_IDLE_TIMEOUT_MS = 30000u;
+    // Idle timeout: time with no incoming bytes before the connection is closed.
+    // Large applications (1000+ signals) can take >30 s to process a DISCOVER/TREE
+    // response, during which no commands are sent — use a generous default.
+    static const uint32 CLIENT_IDLE_TIMEOUT_MS = 120000u;
     static const uint32 INPUT_BUFFER_MAX       = 8192u;
 
     uint32 cmdCountInWindow;

Source/Components/Interfaces/DebugService/DebugServiceBase.cpp

@@ -180,6 +180,8 @@ DebugServiceBase::DebugServiceBase() : ReferenceContainer() {
   isPaused = false;
   stepRemaining = 0u;
   manualConfigSet = false;
+  discoverCacheValid = false;
+  treeCacheValid = false;
 }
 
 DebugServiceBase::~DebugServiceBase() {
@@ -256,6 +258,9 @@ DebugSignalInfo *DebugServiceBase::RegisterSignal(void *memoryAddress,
     res->breakOp = BREAK_OFF;
     res->breakThreshold = 0.0;
     signals.Append(res);
+    // Invalidate caches — new signal registered after the last build.
+    discoverCacheValid = false;
+    treeCacheValid     = false;
   }
   if (sigIdx != 0xFFFFFFFFu) {
     bool found = false;
@@ -716,54 +721,102 @@ void DebugServiceBase::GetSignalValue(const char8 *name, StreamString &out) {
 }
 
 void DebugServiceBase::Discover(StreamString &out) {
-  out += "{\"Signals\":[\n";
+  if (!discoverCacheValid)
+    BuildDiscoverCache();
+  out += discoverCache;
+}
+
+void DebugServiceBase::BuildDiscoverCache() {
+  discoverCacheValid = false;
+  discoverCache      = "";
+
+  // -----------------------------------------------------------------------
+  // Phase 1 — snapshot signal metadata under the mutex (fast, no allocs on
+  //           the RT path because this runs only during initialisation).
+  // -----------------------------------------------------------------------
+  Vector<StreamString> enames;
+  Vector<uint32>       eids;
+  Vector<const char8*> etypes;
+  Vector<uint8>        edims;
+  Vector<uint32>       eelems;
+
   mutex.FastLock();
-  uint32 total = 0u;
   for (uint32 i = 0u; i < aliases.GetNumberOfElements(); i++) {
-    if (total > 0u)
-      out += ",\n";
     DebugSignalInfo *sig = signals[aliases[i].signalIndex];
-    const char8 *tn = TypeDescriptor::GetTypeNameFromTypeDescriptor(sig->type);
-    out.Printf("  {\"name\":\"%s\",\"id\":%u,\"type\":\"%s\","
-               "\"dimensions\":%u,\"elements\":%u",
-               aliases[i].name.Buffer(), sig->internalID, tn ? tn : "Unknown",
-               sig->numberOfDimensions, sig->numberOfElements);
-    EnrichWithConfig(aliases[i].name.Buffer(), out);
-    out += "}";
-    total++;
+    enames.Append(aliases[i].name);
+    eids.Append(sig->internalID);
+    etypes.Append(TypeDescriptor::GetTypeNameFromTypeDescriptor(sig->type));
+    edims.Append(sig->numberOfDimensions);
+    eelems.Append(sig->numberOfElements);
   }
   for (uint32 i = 0u; i < monitoredSignals.GetNumberOfElements(); i++) {
     bool found = false;
     for (uint32 j = 0u; j < aliases.GetNumberOfElements(); j++) {
-      if (aliases[j].name == monitoredSignals[i].path) {
-        found = true;
-        break;
-      }
+      if (aliases[j].name == monitoredSignals[i].path) { found = true; break; }
     }
     if (!found) {
-      if (total > 0u)
-        out += ",\n";
-      const char8 *tn = TypeDescriptor::GetTypeNameFromTypeDescriptor(
-          monitoredSignals[i].dataSource->GetSignalType(
-              monitoredSignals[i].signalIdx));
-      uint8 dims = 0u;
+      uint8  dims  = 0u;
       uint32 elems = 1u;
       (void)monitoredSignals[i].dataSource->GetSignalNumberOfDimensions(
           monitoredSignals[i].signalIdx, dims);
       (void)monitoredSignals[i].dataSource->GetSignalNumberOfElements(
           monitoredSignals[i].signalIdx, elems);
-      out.Printf("  {\"name\":\"%s\",\"id\":%u,\"type\":\"%s\","
-                 "\"dimensions\":%u,\"elements\":%u",
-                 monitoredSignals[i].path.Buffer(),
-                 monitoredSignals[i].internalID, tn ? tn : "Unknown", dims,
-                 elems);
-      EnrichWithConfig(monitoredSignals[i].path.Buffer(), out);
-      out += "}";
-      total++;
+      enames.Append(monitoredSignals[i].path);
+      eids.Append(monitoredSignals[i].internalID);
+      etypes.Append(TypeDescriptor::GetTypeNameFromTypeDescriptor(
+          monitoredSignals[i].dataSource->GetSignalType(
+              monitoredSignals[i].signalIdx)));
+      edims.Append(dims);
+      eelems.Append(elems);
     }
   }
   mutex.FastUnLock();
-  out += "\n]}\nOK DISCOVER\n";
+
+  // -----------------------------------------------------------------------
+  // Phase 2 — build chunked response (no mutex; fullConfig is single-threaded
+  //           at initialisation time when this is called from SetFullConfig).
+  // -----------------------------------------------------------------------
+  uint32 total = enames.GetNumberOfElements();
+
+  if (total == 0u) {
+    discoverCache = "{\"Signals\":[]}\nOK DISCOVER\n";
+    discoverCacheValid = true;
+    return;
+  }
+
+  for (uint32 start = 0u; start < total; start += DISCOVER_CHUNK_SIGNALS) {
+    uint32 end     = start + DISCOVER_CHUNK_SIGNALS;
+    if (end > total) end = total;
+    bool   isFinal = (end >= total);
+
+    discoverCache += "{\"Signals\":[\n";
+    for (uint32 idx = start; idx < end; idx++) {
+      if (idx > start) discoverCache += ",\n";
+      discoverCache.Printf(
+          "  {\"name\":\"%s\",\"id\":%u,\"type\":\"%s\","
+          "\"dimensions\":%u,\"elements\":%u",
+          enames[idx].Buffer(), eids[idx],
+          etypes[idx] ? etypes[idx] : "Unknown",
+          edims[idx], eelems[idx]);
+      EnrichWithConfig(enames[idx].Buffer(), discoverCache);
+      discoverCache += "}";
+    }
+    discoverCache += "\n]}";
+    discoverCache += isFinal ? "\nOK DISCOVER\n" : "\nOK DISCOVER_PART\n";
+  }
+
+  discoverCacheValid = true;
+}
+
+void DebugServiceBase::BuildTreeCache() {
+  treeCacheValid = false;
+  treeCache      = "";
+  treeCache += "{\"Name\":\"Root\",\"Class\":\"ObjectRegistryDatabase\","
+               "\"Children\":[\n";
+  (void)ExportTree(ObjectRegistryDatabase::Instance(), treeCache,
+                   NULL_PTR(const char8 *));
+  treeCache += "\n]}\nOK TREE\n";
+  treeCacheValid = true;
 }
 
 void DebugServiceBase::InfoNode(const char8 *path, StreamString &out) {
@@ -868,6 +921,8 @@ void DebugServiceBase::SetFullConfig(ConfigurationDatabase &config) {
   config.MoveToRoot();
   config.Copy(fullConfig);
   manualConfigSet = true;
+  BuildDiscoverCache();
+  BuildTreeCache();
 }
 
 void DebugServiceBase::RebuildConfigFromRegistry() {
@@ -1234,11 +1289,9 @@ void DebugServiceBase::HandleCommand(const StreamString &cmdIn,
   } else if (token == "DISCOVER") {
     Discover(out);
   } else if (token == "TREE") {
-    out += "{\"Name\":\"Root\",\"Class\":\"ObjectRegistryDatabase\","
-           "\"Children\":[\n";
-    (void)ExportTree(ObjectRegistryDatabase::Instance(), out,
-                     NULL_PTR(const char8 *));
-    out += "\n]}\nOK TREE\n";
+    if (!treeCacheValid)
+      BuildTreeCache();
+    out += treeCache;
   } else if (token == "INFO") {
     StreamString path;
     if (cmd.GetToken(path, delims, term))
@@ -1415,5 +1468,6 @@ void DebugServiceBase::HandleCommand(const StreamString &cmdIn,
 // Out-of-class constant definitions (C++98 ODR requirement)
 // ---------------------------------------------------------------------------
 const uint32 DebugServiceBase::GET_VALUE_MAX_ELEMENTS;
+const uint32 DebugServiceBase::DISCOVER_CHUNK_SIGNALS;
 
 } // namespace MARTe

Source/Components/Interfaces/DebugService/DebugServiceBase.h

@@ -125,6 +125,22 @@ public:
 
     static const uint32 GET_VALUE_MAX_ELEMENTS = 256u;
 
+    /**
+     * @brief Pre-build DISCOVER and TREE response caches.
+     *
+     * Called automatically by SetFullConfig() once the application is fully
+     * initialised.  After this point, DISCOVER and TREE are served from the
+     * pre-built string with no mutex contention and no JSON generation cost.
+     * Both caches are invalidated whenever a new signal is registered (which
+     * normally only happens during broker init, before SetFullConfig).
+     */
+    void BuildDiscoverCache();
+    void BuildTreeCache();
+
+    // Number of signals per DISCOVER_PART TCP chunk.  Responses larger than
+    // this are split so the Go client can start parsing immediately.
+    static const uint32 DISCOVER_CHUNK_SIGNALS = 256u;
+
 protected:
     // =========================================================================
     // Virtual hooks for transport subclasses
@@ -183,6 +199,13 @@ protected:
 
     ConfigurationDatabase fullConfig;
     bool manualConfigSet;
+
+    // Pre-built response caches.  Guarded by mutex (brief lock for swap,
+    // none needed for reads once cacheValid is true and construction is done).
+    StreamString  discoverCache;   // full chunked DISCOVER_PART+DISCOVER payload
+    StreamString  treeCache;       // full TREE payload including sentinel
+    volatile bool discoverCacheValid;
+    volatile bool treeCacheValid;
 };
 
 } // namespace MARTe

Tools/go_web_client/Makefile

@@ -0,0 +1,16 @@
+BINARY   := marte2-web-client
+GIT_HASH := $(shell git rev-parse --short HEAD 2>/dev/null || echo unknown)
+TIMESTAMP := $(shell date -u +%Y%m%d-%H%M%S)
+VERSION  := $(GIT_HASH)-$(TIMESTAMP)
+
+LDFLAGS  := -X main.buildVersion=$(VERSION)
+
+.PHONY: all build clean
+
+all: build
+
+build:
+	CGO_ENABLED=0 go build -ldflags "$(LDFLAGS)" -o $(BINARY) .
+
+clean:
+	rm -f $(BINARY)

Tools/go_web_client/main.go

@@ -13,6 +13,11 @@ import (
 	"github.com/gorilla/websocket"
 )
 
+// buildVersion is injected at link time:
+//
+//	go build -ldflags "-X main.buildVersion=$(git rev-parse --short HEAD)"
+var buildVersion = "dev"
+
 //go:embed static
 var staticFiles embed.FS
 
@@ -159,9 +164,12 @@ func (c *WSClient) handleIncoming(in InMsg) {
 		if d.LogPort == 0 {
 			d.LogPort = 8082
 		}
+		log.Printf("[WS] connect request host=%s cmd=%d udp=%d log=%d",
+			d.Host, d.Port, d.UDPPort, d.LogPort)
 		m.Connect(d.Host, d.Port, d.UDPPort, d.LogPort)
 
 	case "disconnect":
+		log.Printf("[WS] disconnect request")
 		m.Disconnect()
 
 	case "cmd":
@@ -232,6 +240,6 @@ func main() {
 		fileServer.ServeHTTP(w, r)
 	})
 
-	log.Printf("MARTe2 Web Debug Client listening on %s", *addr)
+	log.Printf("MARTe2 Web Debug Client build=%s listening on %s", buildVersion, *addr)
 	log.Fatal(http.ListenAndServe(*addr, nil))
 }

Tools/go_web_client/marte2.go

@@ -5,6 +5,7 @@ import (
 	"encoding/binary"
 	"encoding/json"
 	"fmt"
+	"log"
 	"math"
 	"net"
 	"strings"
@@ -67,8 +68,13 @@ type MarteClient struct {
 
 	connected int32 // atomic bool
 
+	lastWriteMs int64 // atomic; updated on every TCP write, used by keepalive
+
 	stopCh chan struct{}
 
+	// accumulates signals across DISCOVER_PART chunks; merged on final DISCOVER
+	discoverAcc []discoverSignalJSON
+
 	// cached last-known ports (updated by SERVICE_INFO)
 	host    string
 	cmdPort int
@@ -144,6 +150,7 @@ func (m *MarteClient) Disconnect() {
 	m.basesMu.Lock()
 	m.baseTsSet = false
 	m.basesMu.Unlock()
+	m.discoverAcc = nil
 }
 
 func (m *MarteClient) stopped() bool {
@@ -180,6 +187,8 @@ func (m *MarteClient) runTCP(host string, port int) {
 		// Send SERVICE_INFO to auto-discover ports
 		m.writeCmd("SERVICE_INFO")
 
+		go m.runKeepalive()
+
 		m.readLoop(conn)
 
 		atomic.StoreInt32(&m.connected, 0)
@@ -205,8 +214,35 @@ func (m *MarteClient) writeCmd(cmd string) {
 	if w == nil {
 		return
 	}
+	log.Printf("[→MARTe] %s", cmd)
+	broadcast(m.hub, map[string]any{
+		"type": "log", "time": time.Now().Format("15:04:05.000"),
+		"level": "CMD", "message": fmt.Sprintf("→ %s", cmd),
+	})
 	w.WriteString(cmd + "\n")
 	w.Flush()
+	atomic.StoreInt64(&m.lastWriteMs, time.Now().UnixMilli())
+}
+
+// runKeepalive sends INFO every 20 s when no other command has been written
+// in the last 20 s, keeping the DebugService 30 s idle timer from firing.
+func (m *MarteClient) runKeepalive() {
+	ticker := time.NewTicker(20 * time.Second)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-m.stopCh:
+			return
+		case <-ticker.C:
+			if !m.IsConnected() {
+				continue
+			}
+			idleMs := time.Now().UnixMilli() - atomic.LoadInt64(&m.lastWriteMs)
+			if idleMs >= 20_000 {
+				m.writeCmd("INFO")
+			}
+		}
+	}
 }
 
 func (m *MarteClient) SendCommand(cmd string) {
@@ -215,7 +251,7 @@ func (m *MarteClient) SendCommand(cmd string) {
 
 func (m *MarteClient) readLoop(conn net.Conn) {
 	scanner := bufio.NewScanner(conn)
-	scanner.Buffer(make([]byte, 1*1024*1024), 1*1024*1024)
+	scanner.Buffer(make([]byte, 8*1024*1024), 8*1024*1024)
 
 	var jsonAcc strings.Builder
 	inJSON := false
@@ -256,15 +292,18 @@ func (m *MarteClient) readLoop(conn net.Conn) {
 	}
 }
 
-// detectJSONDone returns (tag, true) when the line contains an "OK <TAG>" sentinel.
+// detectJSONDone returns (tag, true) when the line is exactly "OK <TAG>".
+// DISCOVER_PART must appear before DISCOVER so partial chunks are not mistaken
+// for the final chunk (though with exact matching this is not strictly
+// necessary; kept for clarity).
 func detectJSONDone(line string) (string, bool) {
 	tags := []string{
-		"DISCOVER", "TREE", "INFO", "CONFIG", "STEP_STATUS",
+		"DISCOVER_PART", "DISCOVER", "TREE", "INFO", "CONFIG", "STEP_STATUS",
 		"VALUE", "MSG", "TRACE", "FORCE", "UNFORCE", "BREAK",
 		"PAUSE", "RESUME", "STEP", "MONITOR", "UNMONITOR", "LS",
 	}
 	for _, t := range tags {
-		if strings.Contains(line, "OK "+t) {
+		if line == "OK "+t {
 			return t, true
 		}
 	}
@@ -272,11 +311,47 @@ func detectJSONDone(line string) (string, bool) {
 }
 
 func (m *MarteClient) handleJSONResponse(tag, data string) {
+	log.Printf("[←MARTe] %s  %d bytes", tag, len(data))
+	broadcast(m.hub, map[string]any{
+		"type": "log", "time": time.Now().Format("15:04:05.000"),
+		"level": "RESP", "message": fmt.Sprintf("← %s (%d B)", tag, len(data)),
+	})
 	switch tag {
+	case "DISCOVER_PART":
+		// Accumulate this chunk; do NOT broadcast — we wait for the final chunk.
+		var resp discoverResp
+		if err := json.Unmarshal([]byte(data), &resp); err != nil {
+			log.Printf("[DISCOVER_PART] parse error: %v", err)
+			return
+		}
+		m.discoverAcc = append(m.discoverAcc, resp.Signals...)
+		log.Printf("[DISCOVER_PART] accumulated %d signals (total so far: %d)",
+			len(resp.Signals), len(m.discoverAcc))
+		return
+
 	case "DISCOVER":
-		m.parseDiscover(data)
+		// Merge any previously accumulated part-chunks with this final chunk.
+		var resp discoverResp
+		if err := json.Unmarshal([]byte(data), &resp); err != nil {
+			log.Printf("[DISCOVER] parse error: %v", err)
+			return
+		}
+		all := append(m.discoverAcc, resp.Signals...)
+		m.discoverAcc = nil
+		m.parseDiscoverSignals(all)
+		// Re-marshal the merged list so the browser gets a single consistent blob.
+		merged, _ := json.Marshal(discoverResp{Signals: all})
+		broadcast(m.hub, map[string]any{
+			"type": "response", "tag": "DISCOVER", "data": string(merged),
+		})
+		return
+
+	case "TREE":
+		// Parse server-side and stream pre-digested flat-node batches to the
+		// browser so it never has to JSON.parse a multi-MB string.
+		go m.sendTreeBatches(data)
+		return
 	}
-	// Forward raw JSON to all browsers.
 	broadcast(m.hub, map[string]any{
 		"type": "response",
 		"tag":  tag,
@@ -284,6 +359,91 @@ func (m *MarteClient) handleJSONResponse(tag, data string) {
 	})
 }
 
+// ---------------------------------------------------------------------------
+// TREE streaming
+// ---------------------------------------------------------------------------
+
+// TreeNode mirrors the DebugService TREE JSON structure.
+type TreeNode struct {
+	Name        string      `json:"Name"`
+	Class       string      `json:"Class"`
+	IsTraceable bool        `json:"IsTraceable"`
+	IsForcable  bool        `json:"IsForcable"`
+	Elements    uint32      `json:"Elements"`
+	Children    []*TreeNode `json:"Children"`
+}
+
+// FlatNode is a pre-digested, compact representation sent to the browser.
+type FlatNode struct {
+	Path   string `json:"p"`
+	Name   string `json:"n"`
+	Class  string `json:"c"`
+	Parent string `json:"par"`
+	Tr     bool   `json:"tr,omitempty"`
+	Fo     bool   `json:"fo,omitempty"`
+	El     uint32 `json:"el,omitempty"`
+	HasCh  bool   `json:"ch,omitempty"`
+}
+
+func flattenTree(node *TreeNode, parentPath string, out *[]FlatNode) {
+	path := node.Name
+	if parentPath != "" {
+		path = parentPath + "." + node.Name
+	}
+	hasCh := len(node.Children) > 0
+	*out = append(*out, FlatNode{
+		Path:  path,
+		Name:  node.Name,
+		Class: node.Class,
+		Parent: parentPath,
+		Tr:    node.IsTraceable,
+		Fo:    node.IsForcable,
+		El:    node.Elements,
+		HasCh: hasCh,
+	})
+	for _, c := range node.Children {
+		flattenTree(c, path, out)
+	}
+}
+
+// sendTreeBatches parses the raw TREE JSON and streams compact FlatNode
+// batches to all browsers. Each browser processes one batch per animation
+// frame, keeping the UI responsive during large tree loads.
+func (m *MarteClient) sendTreeBatches(raw string) {
+	var root TreeNode
+	if err := json.Unmarshal([]byte(raw), &root); err != nil {
+		log.Printf("[TREE] parse error: %v — falling back to raw JSON", err)
+		broadcast(m.hub, map[string]any{"type": "response", "tag": "TREE", "data": raw})
+		return
+	}
+
+	var nodes []FlatNode
+	if root.Name == "Root" && len(root.Children) > 0 {
+		for _, c := range root.Children {
+			flattenTree(c, "", &nodes)
+		}
+	} else {
+		flattenTree(&root, "", &nodes)
+	}
+
+	total := len(nodes)
+	log.Printf("[TREE] streaming %d flat nodes to browser", total)
+	broadcast(m.hub, map[string]any{"type": "tree_clear", "total": total})
+
+	const batchSize = 50
+	for i := 0; i < total; i += batchSize {
+		end := i + batchSize
+		if end > total {
+			end = total
+		}
+		broadcast(m.hub, map[string]any{
+			"type":  "tree_batch",
+			"nodes": nodes[i:end],
+			"done":  end == total,
+		})
+	}
+}
+
 func (m *MarteClient) handleTextLine(line string) {
 	if strings.HasPrefix(line, "OK SERVICE_INFO") {
 		// OK SERVICE_INFO TCP_CTRL:8110 UDP_STREAM:8111 TCP_LOG:8082 STATE:RUNNING
@@ -340,29 +500,35 @@ func (m *MarteClient) handleTextLine(line string) {
 // DISCOVER parsing
 // ---------------------------------------------------------------------------
 
-type discoverResp struct {
-	Signals []struct {
-		Name       string `json:"name"`
-		ID         uint32 `json:"id"`
-		Type       string `json:"type"`
-		Dimensions uint8  `json:"dimensions"`
-		Elements   uint32 `json:"elements"`
-	} `json:"Signals"`
+type discoverSignalJSON struct {
+	Name       string `json:"name"`
+	ID         uint32 `json:"id"`
+	Type       string `json:"type"`
+	Dimensions uint8  `json:"dimensions"`
+	Elements   uint32 `json:"elements"`
 }
 
-func (m *MarteClient) parseDiscover(data string) {
-	var resp discoverResp
-	if err := json.Unmarshal([]byte(data), &resp); err != nil {
-		return
-	}
+type discoverResp struct {
+	Signals []discoverSignalJSON `json:"Signals"`
+}
+
+func (m *MarteClient) parseDiscoverSignals(sigs []discoverSignalJSON) {
 	m.sigMu.Lock()
 	defer m.sigMu.Unlock()
-	m.signals = make(map[uint32]*SignalMeta, len(resp.Signals))
-	for _, s := range resp.Signals {
+	m.signals = make(map[uint32]*SignalMeta, len(sigs))
+	for _, s := range sigs {
 		el := s.Elements
 		if el == 0 {
 			el = 1
 		}
+		// Multiple DISCOVER entries can share the same ID (canonical DataSource
+		// path + one GAM alias per broker).  Merge them into one SignalMeta so
+		// that Names carries every alias.  This is required for the telemetry
+		// receiver to match whichever name the user traced.
+		if existing, ok := m.signals[s.ID]; ok {
+			existing.Names = append(existing.Names, s.Name)
+			continue
+		}
 		meta := &SignalMeta{
 			Name:       s.Name,
 			ID:         s.ID,
@@ -373,6 +539,7 @@ func (m *MarteClient) parseDiscover(data string) {
 		}
 		m.signals[s.ID] = meta
 	}
+	log.Printf("[DISCOVER] registered %d unique signals from %d entries", len(m.signals), len(sigs))
 }
 
 // ---------------------------------------------------------------------------

Tools/go_web_client/static/app.js

@@ -75,32 +75,189 @@ function sendCmd(cmd) { sendWS({type:'cmd', data:{cmd}}); }
 
 function handleMsg(msg) {
   switch (msg.type) {
-    case 'connected':    onMarteConnected(); break;
-    case 'disconnected': onMarteDisconnected(); break;
-    case 'signal_cache': onSignalCache(msg); break;
-    case 'response':     onResponse(msg); break;
-    case 'text_line':    onTextLine(msg.data); break;
-    case 'telemetry':    onTelemetry(msg); break;
-    case 'log':          onLog(msg); break;
+    case 'connected':      onMarteConnected(); break;
+    case 'disconnected':   onMarteDisconnected(); break;
+    case 'signal_cache':   onSignalCache(msg); break;
+    case 'response':       onResponse(msg); break;
+    case 'text_line':      onTextLine(msg.data); break;
+    case 'telemetry':      onTelemetry(msg); break;
+    case 'log':            onLog(msg); break;
     case 'service_config': onServiceConfig(msg); break;
-    case 'udp_stats':    onUdpStats(msg); break;
+    case 'udp_stats':      onUdpStats(msg); break;
+    case 'tree_clear':     onTreeClear(msg.total); break;
+    case 'tree_batch':     onTreeBatch(msg); break;
   }
 }
 
+// ════════════════════════════════════════════════════════════════════
+// Incremental tree rendering (server-side pre-processed batches)
+//
+// Batches are stored purely in memory — no DOM work during receipt.
+// DOM nodes are created lazily: only the top-level containers are
+// built immediately; everything inside a closed <details> is deferred
+// until the user opens it.  This keeps the initial render O(1) in the
+// number of signals regardless of tree size.
+// ════════════════════════════════════════════════════════════════════
+
+let _treeBuild  = null;  // { threads:[], objects:[] } — null when idle
+let _flatNodes  = null;  // Map<path, FlatNode>
+let _childrenOf = null;  // Map<parentPath|'', FlatNode[]>
+
+function onTreeClear(total) {
+  _treeBuild  = { threads: [], objects: [] };
+  _flatNodes  = new Map();
+  _childrenOf = new Map();
+  document.getElementById('tree-body').innerHTML = '';
+  appendLog('sys', 'INFO', `Receiving tree (${total} nodes)…`);
+}
+
+function onTreeBatch(msg) {
+  if (!_treeBuild) return;
+  // Pure memory work — no DOM touched here.
+  for (const node of (msg.nodes || [])) {
+    _flatNodes.set(node.p, node);
+    const pk = node.par || '';
+    let ch = _childrenOf.get(pk);
+    if (!ch) { ch = []; _childrenOf.set(pk, ch); }
+    ch.push(node);
+    if (node.c === 'RealTimeThread' && node.n) _treeBuild.threads.push(node.n);
+    if (node.c && node.c !== 'Signal' && node.n) _treeBuild.objects.push(node.p);
+  }
+
+  if (!msg.done) return;
+
+  // All batches received — build only top-level nodes now.
+  const body = document.getElementById('tree-body');
+  const frag = document.createDocumentFragment();
+  for (const node of (_childrenOf.get('') || [])) {
+    frag.appendChild(_buildFlatNode(node));
+  }
+  body.appendChild(frag);
+
+  // Finalise autocompletes.
+  threads    = _treeBuild.threads;
+  allObjects = _treeBuild.objects;
+  ['step-thread','step-thread-list','step-thread-inp'].forEach(id => {
+    const el = document.getElementById(id);
+    if (!el) return;
+    if (el.tagName === 'SELECT') {
+      el.innerHTML = '<option value="">— all threads —</option>' +
+        threads.map(t => `<option value="${esc(t)}">${esc(t)}</option>`).join('');
+    } else if (el.tagName === 'DATALIST') {
+      el.innerHTML = threads.map(t => `<option value="${esc(t)}">`).join('');
+    }
+  });
+  document.getElementById('msg-dest-list').innerHTML =
+    allObjects.map(n => `<option value="${esc(n)}">`).join('');
+
+  _treeBuild = null;
+  _treeReady = true;
+  appendLog('sys', 'INFO', `Tree ready — ${allObjects.length} objects, ${threads.length} threads`);
+  startStepPoll();
+}
+
+// Build one flat node into a DOM element.  Containers install a toggle
+// listener that builds their children on first open (lazy load).
+function _buildFlatNode(node) {
+  if (node.ch) {
+    const details = document.createElement('details');
+    const summary = document.createElement('summary');
+    summary.innerHTML =
+      `<span class="tree-name">${esc(node.n)}</span>` +
+      `<span class="tree-class">[${esc(node.c)}]</span>`;
+    details.appendChild(summary);
+    details.addEventListener('toggle', function() {
+      if (!details.open || details._childrenBuilt) return;
+      details._childrenBuilt = true;
+      const childDiv = document.createElement('div');
+      childDiv.className = 'children';
+      const infoBtn = makeLeafButtons(node.p);
+      if (infoBtn) childDiv.appendChild(infoBtn);
+      const f = document.createDocumentFragment();
+      for (const child of (_childrenOf.get(node.p) || [])) {
+        f.appendChild(_buildFlatNode(child));
+      }
+      childDiv.appendChild(f);
+      details.appendChild(childDiv);
+    });
+    return details;
+  }
+
+  // Leaf node.
+  const isSig = node.c === 'Signal' || node.tr;
+  const item  = { Name: node.n, Class: node.c, IsTraceable: node.tr, IsForcable: node.fo };
+  const row   = document.createElement('div');
+  row.className = 'tree-node';
+  row.appendChild(makeLeafRow(node.p, item, isSig));
+  if (isSig && node.el > 1) {
+    const sub = document.createElement('div');
+    sub.style.paddingLeft = '14px';
+    for (let i = 0; i < node.el; i++) {
+      const en = `${node.p}[${i}]`;
+      sub.appendChild(makeLeafRow(en,
+        { Name:`[${i}]`, Class:'Signal', IsTraceable:true, IsForcable:node.fo }, true));
+    }
+    row.appendChild(sub);
+  }
+  return row;
+}
+
+// Force-build all lazy containers (used before a DOM-wide filter search).
+function _buildAllTreeNodes(root) {
+  let dirty = true;
+  while (dirty) {
+    dirty = false;
+    root.querySelectorAll('details').forEach(d => {
+      if (!d._childrenBuilt) { d.open = true; dirty = true; }
+    });
+  }
+}
+
+// ════════════════════════════════════════════════════════════════════
+// Startup sequencing
+//
+// The server (DebugService) can be very busy during application init
+// (1000+ signals, registry patching, broker setup). Sending DISCOVER
+// or STEP_STATUS before it is ready just fills its receive buffer,
+// delaying every subsequent response and triggering idle timeouts.
+//
+// Correct sequence:
+//   connect → SERVICE_INFO → DISCOVER → TREE → STEP_STATUS poll
+//
+// Each step is gated on the previous one completing.  sendOnce()
+// prevents the same command from being queued twice across reconnects.
+// ════════════════════════════════════════════════════════════════════
+
+const _cmdSent = new Set();
+let _treeReady = false; // hard gate: STEP_STATUS never starts before tree is built
+
+function sendOnce(cmd) {
+  if (_cmdSent.has(cmd)) return;
+  _cmdSent.add(cmd);
+  sendCmd(cmd);
+}
+
+function _clearStartupState() {
+  _cmdSent.clear();
+  _treeReady = false;
+  stopStepPoll(); // always kill any running poll when state is reset
+}
+
 function onMarteConnected() {
   marteConnected = true;
+  _clearStartupState();
   document.getElementById('conn-status').classList.add('ok');
   document.getElementById('btn-connect').textContent = 'Disconnect';
   appendLog('sys','INFO','Connected to MARTe2');
-  // Auto-discover
-  sendCmd('DISCOVER');
-  sendCmd('TREE');
-  // Start polling step status
-  startStepPoll();
+  // Send DISCOVER immediately so the user gets feedback without waiting for
+  // SERVICE_INFO.  STEP_STATUS is gated by _treeReady so the server is not
+  // flooded with status polls during the (potentially long) init phase.
+  sendOnce('DISCOVER');
 }
 
 function onMarteDisconnected() {
   marteConnected = false;
+  _clearStartupState();
   document.getElementById('conn-status').classList.remove('ok');
   document.getElementById('btn-connect').textContent = 'Connect';
   appendLog('sys','WARNING','Disconnected from MARTe2');
@@ -108,16 +265,26 @@ function onMarteDisconnected() {
 }
 
 function onSignalCache(msg) {
-  // Server sends cached signal list when a new browser connects mid-session
-  if (msg.signals) processDiscovery(msg.signals);
+  // Go server has cached signals from a previous DISCOVER — skip DISCOVER,
+  // go straight to TREE (still need the object hierarchy).
+  if (msg.signals) {
+    processDiscovery(msg.signals);
+    _cmdSent.add('DISCOVER'); // mark as done so fallback timer doesn't re-send
+    sendOnce('TREE');
+  }
 }
 
 function onResponse(msg) {
   try {
     const data = msg.data ? JSON.parse(msg.data) : null;
     switch (msg.tag) {
-      case 'DISCOVER':     if (data) processDiscovery(data.Signals || []); break;
-      case 'TREE':         if (data) processTree(data); break;
+      case 'DISCOVER':
+        if (data) {
+          processDiscovery(data.Signals || []);
+          sendOnce('TREE');
+        }
+        break;
+      case 'TREE':         if (data) processTree(data); break; // fallback if Go parse fails
       case 'INFO':         showInfo(msg.tag, msg.data); break;
       case 'CONFIG':       showInfo('CONFIG', msg.data); break;
       case 'SERVICE_INFO': showInfo('Service Info', msg.data); break;
@@ -165,9 +332,16 @@ function onTelemetry(msg) {
   for (const s of msg.signals) {
     const names = s.names || [];
     const vals = s.values || [];
+    let plotDirty = false;
     for (let e = 0; e < vals.length; e++) {
-      const n = vals.length > 1 ? `${names[0]}[${e}]` : (names[0] || '');
-      if (!n || !tracedSet.has(n)) continue;
+      // A signal can have multiple names (canonical DataSource path + GAM
+      // aliases).  Find whichever name the user actually traced.
+      let n = '';
+      for (const nm of names) {
+        const candidate = vals.length > 1 ? `${nm}[${e}]` : nm;
+        if (tracedSet.has(candidate)) { n = candidate; break; }
+      }
+      if (!n) continue;
       let td = traceData[n];
       if (!td) {
         td = {ts:[], vals:[], lastVal:0, color: nextColor()};
@@ -176,25 +350,26 @@ function onTelemetry(msg) {
       td.ts.push(s.ts);
       td.vals.push(vals[e]);
       td.lastVal = vals[e];
-      // Trim to max points
       if (td.ts.length > MAX_TRACE_PTS) {
         const trim = td.ts.length - MAX_TRACE_PTS;
         td.ts.splice(0, trim);
         td.vals.splice(0, trim);
       }
+      plotDirty = true;
     }
-    // Mark plots dirty
-    for (const p of plots) {
-      for (const sr of p.series) {
-        if (names.includes(sr.name) || (vals.length>1 && names.length>0 &&
-            p.series.some(x => x.name.startsWith(names[0])))) {
-          p.dirty = true;
-          break;
+    // Mark plots dirty if any of this signal's names appear in a series.
+    if (plotDirty) {
+      for (const p of plots) {
+        for (const sr of p.series) {
+          if (names.some(nm => sr.name === nm ||
+              (vals.length > 1 && sr.name.startsWith(nm + '[')))) {
+            p.dirty = true;
+            break;
+          }
         }
       }
     }
   }
-  // Update only the value spans — never rebuild the DOM here
   updateTracedValues();
 }
 
@@ -234,13 +409,25 @@ function updateSignalAutocomplete() {
 function processTree(root) {
   threads = [];
   allObjects = [];
+
+  // Fast metadata pass: traverse the raw JSON tree to collect threads and
+  // object names without touching the DOM at all.
+  function collectMeta(item, parentPath) {
+    const path = parentPath ? parentPath + '.' + item.Name : item.Name;
+    if (item.Class === 'RealTimeThread' && item.Name) threads.push(item.Name);
+    if (item.Class && item.Class !== 'Signal' && item.Name) allObjects.push(path);
+    if (item.Children) for (const c of item.Children) collectMeta(c, path);
+  }
+  collectMeta(root, '');
+
+  // Build only the top-level nodes now; everything deeper is lazy.
   const body = document.getElementById('tree-body');
   body.innerHTML = '';
-  if (root.Name === 'Root' && root.Children) {
-    for (const child of root.Children) body.appendChild(buildTreeNode(child, ''));
-  } else {
-    body.appendChild(buildTreeNode(root, ''));
-  }
+  const frag = document.createDocumentFragment();
+  const topNodes = (root.Name === 'Root' && root.Children) ? root.Children : [root];
+  for (const child of topNodes) frag.appendChild(buildTreeNode(child, ''));
+  body.appendChild(frag);
+
   // Populate thread selects
   ['step-thread','step-thread-list','step-thread-inp'].forEach(id=>{
     const el = document.getElementById(id);
@@ -255,28 +442,33 @@ function processTree(root) {
   // Populate msg dest autocomplete
   const dl = document.getElementById('msg-dest-list');
   dl.innerHTML = allObjects.map(n=>`<option value="${esc(n)}">`).join('');
+  _treeReady = true;
+  startStepPoll(); // fallback path: Go couldn't parse TREE, tree_batch never fires
 }
 
 function buildTreeNode(item, parentPath) {
   const path = parentPath ? parentPath + '.' + item.Name : item.Name;
   const isSig = item.Class === 'Signal' || item.IsTraceable;
-  const isThread = item.Class === 'RealTimeThread';
-
-  if (isThread && item.Name) threads.push(item.Name);
-  if (item.Class && item.Class !== 'Signal' && item.Name) allObjects.push(path);
 
   if (item.Children && item.Children.length > 0) {
     const details = document.createElement('details');
     const summary = document.createElement('summary');
     summary.innerHTML = `<span class="tree-name">${esc(item.Name)}</span><span class="tree-class">[${esc(item.Class)}]</span>`;
     details.appendChild(summary);
-    const children = document.createElement('div');
-    children.className = 'children';
-    // Info button for container nodes
-    const leaf = makeLeafButtons(path);
-    if (leaf) children.appendChild(leaf);
-    for (const c of item.Children) children.appendChild(buildTreeNode(c, path));
-    details.appendChild(children);
+
+    // Children are built lazily on first open — avoids creating thousands of
+    // DOM nodes for a large app when the user may never open most branches.
+    details.addEventListener('toggle', function() {
+      if (!details.open || details._childrenBuilt) return;
+      details._childrenBuilt = true;
+      const children = document.createElement('div');
+      children.className = 'children';
+      const leaf = makeLeafButtons(path);
+      if (leaf) children.appendChild(leaf);
+      for (const c of item.Children) children.appendChild(buildTreeNode(c, path));
+      details.appendChild(children);
+    });
+
     return details;
   }
 
@@ -363,14 +555,16 @@ function mkBtn(label, cls, fn) {
 function filterTree(q) {
   const body = document.getElementById('tree-body');
   q = q.toLowerCase();
+  if (q) {
+    // Build all lazy nodes so the querySelectorAll below sees everything.
+    _buildAllTreeNodes(body);
+    body.querySelectorAll('details').forEach(d => d.open = true);
+  }
   body.querySelectorAll('.tree-leaf').forEach(el => {
     if (!q) { el.style.display = ''; return; }
     const t = (el.querySelector('.tree-name')?.title || '').toLowerCase();
     el.style.display = t.includes(q) ? '' : 'none';
   });
-  if (q) {
-    body.querySelectorAll('details').forEach(d => d.open = true);
-  }
 }
 
 // ════════════════════════════════════════════════════════════════════
@@ -628,6 +822,7 @@ function step(n) {
 }
 
 function startStepPoll() {
+  if (!_treeReady) return; // hard gate: never poll before tree is fully built
   stopStepPoll();
   stepPollTimer = setInterval(() => sendCmd('STEP_STATUS'), 2000);
 }
@@ -647,8 +842,10 @@ function processStepStatus(data) {
       data.StepRemaining > 0 ? `(${data.StepRemaining} remaining)` : '';
     document.getElementById('btn-pause').textContent = '▶ Resume';
     // Faster polling while paused
-    stopStepPoll();
-    stepPollTimer = setInterval(() => sendCmd('STEP_STATUS'), 500);
+    if (_treeReady) {
+      stopStepPoll();
+      stepPollTimer = setInterval(() => sendCmd('STEP_STATUS'), 500);
+    }
   } else {
     if (isPaused) {
       isPaused = false;
@@ -1130,12 +1327,15 @@ document.addEventListener('click', e => {
 // Panel collapse
 // ════════════════════════════════════════════════════════════════════
 
-function togglePanelStrip(panelId, stripId, collapseIcon, expandIcon) {
+function togglePanelStrip(panelId) {
   const panel = document.getElementById(panelId);
-  const strip = document.getElementById(stripId);
   if (!panel) return;
-  const collapsed = panel.classList.toggle('collapsed');
-  if (strip) strip.textContent = collapsed ? expandIcon : collapseIcon;
+  const wasCollapsed = panel.classList.toggle('collapsed');
+  if (!wasCollapsed) {
+    // Expanding: restore the last manual width if one was saved
+    const saved = panel.dataset.savedWidth;
+    if (saved) panel.style.width = saved;
+  }
 }
 
 function togglePanel(panelId, collapseIcon, expandIcon, btn) {
@@ -1145,9 +1345,62 @@ function togglePanel(panelId, collapseIcon, expandIcon, btn) {
   if (btn) btn.textContent = collapsed ? expandIcon : collapseIcon;
 }
 
+function setupPanelResize(stripId, panelId, growDir) {
+  // growDir: 'right' means dragging right widens the panel (left panel),
+  //          'left'  means dragging left  widens the panel (right panel).
+  const strip = document.getElementById(stripId);
+  const panel = document.getElementById(panelId);
+  if (!strip || !panel) return;
+
+  strip.addEventListener('mousedown', e => {
+    if (e.button !== 0) return;
+    e.preventDefault();
+
+    const startX    = e.clientX;
+    const startW    = panel.offsetWidth;
+    let   moved     = false;
+
+    const onMove = ev => {
+      const dx = ev.clientX - startX;
+      if (!moved && Math.abs(dx) < 4) return;
+      moved = true;
+
+      // Expand collapsed panel as soon as drag begins
+      if (panel.classList.contains('collapsed')) {
+        panel.classList.remove('collapsed');
+      }
+      panel.style.transition = 'none';
+      document.body.style.cursor = 'col-resize';
+
+      const newW = Math.max(120, Math.min(700,
+        growDir === 'right' ? startW + dx : startW - dx));
+      panel.style.width = newW + 'px';
+      panel.dataset.savedWidth = panel.style.width;
+    };
+
+    const onUp = () => {
+      document.removeEventListener('mousemove', onMove);
+      document.removeEventListener('mouseup', onUp);
+      panel.style.transition = '';
+      document.body.style.cursor = '';
+
+      if (!moved) {
+        // Plain click — toggle collapse
+        togglePanelStrip(panelId);
+      }
+    };
+
+    document.addEventListener('mousemove', onMove);
+    document.addEventListener('mouseup', onUp);
+  });
+}
+
 // ════════════════════════════════════════════════════════════════════
 // Boot
 // ════════════════════════════════════════════════════════════════════
 
 connectWS();
 requestAnimationFrame(renderLoop);
+setupPanelResize('left-strip',  'left-panel',  'right');
+setupPanelResize('right-strip', 'right-panel', 'left');
+addPlot();

Tools/go_web_client/static/index.html

@@ -61,11 +61,13 @@ label{color:#a6adc8;user-select:none}
 #right-panel.collapsed{width:0!important;border:none;overflow:hidden}
 #log-panel{transition:height .15s}
 #log-panel.collapsed{height:28px;overflow:hidden}
-/* collapse toggle strips */
-.panel-strip{width:14px;flex-shrink:0;display:flex;align-items:center;justify-content:center;cursor:pointer;background:#181825;border:1px solid #313244;color:#585b70;font-size:10px;writing-mode:horizontal-tb;user-select:none}
-.panel-strip:hover{background:#313244;color:#cdd6f4}
-#left-strip{border-left:none;border-top:none;border-bottom:none}
-#right-strip{border-right:none;border-top:none;border-bottom:none}
+/* collapse/resize strips */
+.panel-strip{width:6px;flex-shrink:0;display:flex;align-items:center;justify-content:center;cursor:col-resize;background:#181825;border:none;color:#585b70;font-size:9px;user-select:none;position:relative}
+.panel-strip::after{content:'';position:absolute;top:50%;left:50%;transform:translate(-50%,-50%);width:2px;height:32px;background:#45475a;border-radius:1px;pointer-events:none}
+.panel-strip:hover{background:#313244}
+.panel-strip:hover::after{background:#89b4fa}
+#left-strip{border-right:1px solid #313244}
+#right-strip{border-left:1px solid #313244}
 
 /* ── tree ── */
 .tree-node{padding:1px 0}
@@ -244,16 +246,16 @@ select{background:#313244;border:1px solid #45475a;color:#cdd6f4;padding:2px 4px
     </div>
   </div>
 
-  <!-- Left collapse strip -->
-  <div id="left-strip" class="panel-strip" title="Toggle left panel" onclick="togglePanelStrip('left-panel','left-strip','◀','▶')">◀</div>
+  <!-- Left resize/collapse strip -->
+  <div id="left-strip" class="panel-strip" title="Drag to resize · Click to collapse"></div>
 
   <!-- CENTER: plots -->
   <div id="center-panel">
     <div class="empty-hint" id="no-plots-hint">Add a plot panel to begin — drag signals from the tree or traced list</div>
   </div>
 
-  <!-- Right collapse strip -->
-  <div id="right-strip" class="panel-strip" title="Toggle right panel" onclick="togglePanelStrip('right-panel','right-strip','▶','◀')">▶</div>
+  <!-- Right resize/collapse strip -->
+  <div id="right-strip" class="panel-strip" title="Drag to resize · Click to collapse"></div>
 
   <!-- RIGHT: tabs -->
   <div id="right-panel">