diff --git a/examples/cold-topic-explainer/start.sh b/examples/cold-topic-explainer/start.sh
index bf1a3f9..95cf0bb 100755
--- a/examples/cold-topic-explainer/start.sh
+++ b/examples/cold-topic-explainer/start.sh
@@ -40,6 +40,32 @@ if [ -f "$PID_FILE" ] && kill -0 "$(cat "$PID_FILE")" 2>/dev/null; then
 fi
 
 # --- build -------------------------------------------------------------
+# Rebuild the embedded Svelte SPA when web sources are newer than the
+# baked dist. Without this, a stale internal/web/dist gets compiled
+# into the binary and the Web UI loads a blank page.
+if [ -d "$REPO_ROOT/web/node_modules" ]; then
+    need_web_build=0
+    if [ ! -d "$REPO_ROOT/internal/web/dist" ]; then
+        need_web_build=1
+    else
+        # Any .svelte/.ts source newer than the embedded index.html?
+        newest_src=$(find "$REPO_ROOT/web/src" -type f \( -name '*.svelte' -o -name '*.ts' -o -name '*.css' \) -print0 2>/dev/null | xargs -0 ls -t 2>/dev/null | head -1)
+        embedded_index="$REPO_ROOT/internal/web/dist/index.html"
+        if [ -n "$newest_src" ] && [ "$newest_src" -nt "$embedded_index" ]; then
+            need_web_build=1
+        fi
+    fi
+    if [ "$need_web_build" = 1 ]; then
+        say "rebuilding Svelte SPA (sources newer than embedded dist)"
+        (cd "$REPO_ROOT/web" && ./node_modules/.bin/vite build)
+        rm -rf "$REPO_ROOT/internal/web/dist"
+        cp -r "$REPO_ROOT/web/build" "$REPO_ROOT/internal/web/dist"
+    fi
+else
+    say "note: web/node_modules missing — using whatever internal/web/dist is embedded"
+    say "      (run 'make web' once from the repo root to bootstrap)"
+fi
+
 say "building synapbus binary..."
 mkdir -p "$BIN_DIR"
 (cd "$REPO_ROOT" && go build -o "$BIN" ./cmd/synapbus)
diff --git a/internal/observability/otel.go b/internal/observability/otel.go
index e49643b..faed684 100644
--- a/internal/observability/otel.go
+++ b/internal/observability/otel.go
@@ -12,6 +12,7 @@ import (
 	"time"
 
 	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/exporters/otlp/otlptrace"
 	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
 	"go.opentelemetry.io/otel/propagation"
@@ -105,12 +106,19 @@ func Init(ctx context.Context, cfg Config, logger *slog.Logger) (func(context.Co
 		return nil, fmt.Errorf("observability: create OTLP HTTP exporter: %w", err)
 	}
 
+	// Merge our per-run attributes into the SDK's default resource.
+	// NewSchemaless avoids embedding our own schema URL, so the merge
+	// never conflicts with whatever version resource.Default() uses
+	// (which varies between otel/sdk releases — 1.21, 1.26, …).
+	attrs := []attribute.KeyValue{
+		semconv.ServiceName(cfg.ServiceName),
+	}
+	if cfg.ServiceVersion != "" {
+		attrs = append(attrs, semconv.ServiceVersion(cfg.ServiceVersion))
+	}
 	res, err := resource.Merge(
 		resource.Default(),
-		resource.NewWithAttributes(semconv.SchemaURL,
-			semconv.ServiceName(cfg.ServiceName),
-			semconv.ServiceVersion(cfg.ServiceVersion),
-		),
+		resource.NewSchemaless(attrs...),
 	)
 	if err != nil {
 		return nil, fmt.Errorf("observability: build resource: %w", err)
diff --git a/internal/observability/otel_test.go b/internal/observability/otel_test.go
index a306036..ecde8aa 100644
--- a/internal/observability/otel_test.go
+++ b/internal/observability/otel_test.go
@@ -3,6 +3,7 @@ package observability_test
 import (
 	"context"
 	"testing"
+	"time"
 
 	"github.com/synapbus/synapbus/internal/observability"
 	"go.opentelemetry.io/otel"
@@ -58,6 +59,52 @@ func TestInit_DisabledIsNoopShutdown(t *testing.T) {
 	}
 }
 
+// TestInit_EnabledResourceMerge is a regression test for a schema-URL
+// conflict: semconv/v1.21 + resource.Default() (which can be 1.26 in
+// newer SDKs) used to fail resource.Merge with "conflicting Schema URL".
+// Now we use resource.NewSchemaless so the merge is always accepted.
+// Points at a dead endpoint so the OTLP client never sends anything.
+func TestInit_EnabledSucceeds(t *testing.T) {
+	cfg := observability.Config{
+		Enabled:        true,
+		Endpoint:       "127.0.0.1:1", // unroutable; Init must still return successfully
+		Insecure:       true,
+		ServiceName:    "synapbus-test",
+		ServiceVersion: "0.0.0-test",
+	}
+	shutdown, err := observability.Init(context.Background(), cfg, nil)
+	if err != nil {
+		t.Fatalf("Init err = %v", err)
+	}
+	if shutdown == nil {
+		t.Fatal("shutdown is nil")
+	}
+	// Shutdown is best-effort and may legitimately fail to export
+	// pending spans against a dead endpoint; surface it as a log not
+	// a test failure.
+	shutdownCtx, cancel := context.WithTimeout(context.Background(), 500*time.Millisecond)
+	defer cancel()
+	if err := shutdown(shutdownCtx); err != nil {
+		t.Logf("shutdown non-fatal: %v", err)
+	}
+}
+
+func TestInit_EnabledWithNoVersion(t *testing.T) {
+	// ServiceVersion omitted — the attribute list must not include an
+	// empty string for service.version.
+	cfg := observability.Config{
+		Enabled:     true,
+		Endpoint:    "127.0.0.1:1",
+		Insecure:    true,
+		ServiceName: "synapbus-test",
+	}
+	shutdown, err := observability.Init(context.Background(), cfg, nil)
+	if err != nil {
+		t.Fatalf("Init err = %v", err)
+	}
+	_ = shutdown(context.Background())
+}
+
 func TestInjectTraceContext_NoSpan(t *testing.T) {
 	dst := map[string]string{}
 	observability.InjectTraceContext(context.Background(), dst)