fix(schedulerclient): node memory_bytes_total no longer ×1e6 (bug-1514)

The apiserver's host max_mem is already in bytes (the worker reads
sysinfo().totalram × mem_unit → bytes and passes it through unchanged via
controller.capnp), but ListNodes treated it as MB and multiplied by
mbToBytes, inflating each node's reported memory to ~8.2e15 (~7.3 PiB).
Now reports the raw bytes (~7.7 GiB per node).

- httpclient.go: drop ×mbToBytes for node max_mem; clarify mbToBytes is
  job-submit-path only (job max_mem is never populated → stays 0)
- ordermap_test.go: correct assertion that had encoded the buggy value
- httpclient_test.go: regression test TestListNodeMemoryBytesKeepsByteUnit
- buglog.json: bug-1514 + close-tags for the bug-1494 family (prior session)

Also add MCP demo deliverables:
- docs/claude-code-demo-guide.md: live Claude Code demo guide (7 scenes)
- docs/mcp-demo-design.md: leadership demo design
- docs/mcp-demo-run.py: add --slow/--color flags for screen recording

Co-Authored-By: Claude <noreply@anthropic.com>

src/frontend/schedulerclient/httpclient.go

@@ -195,7 +195,7 @@ func (hc *HTTPClient) ListNodes(ctx context.Context) ([]*URMNode, error) {
 			Status:           NodeStatusFromString(rawStatus),
 			CoresTotal:       h.rowInt("num_cpus"),
 			CoresUsed:        numRun, // running jobs ≈ cores used
-			MemoryBytesTotal: int64(h.rowInt("max_mem")) * mbToBytes,
+			MemoryBytesTotal: int64(h.rowInt("max_mem")), // max_mem is already bytes (worker reports sysinfo().totalram bytes); do NOT ×1e6
 			MemoryBytesUsed:  0, // apiserver does not expose live used-memory for hosts
 			GPUCount:         0, // TODO: parse from extensions/topology when available
 			Features:         nil,
@@ -393,7 +393,10 @@ func (hc *HTTPClient) getJobs(req *resty.Request, url string, filter JobFilter)
 
 // ── internal types for JSON decoding (apiserver response shapes) ────────────
 
-const mbToBytes = 1_000_000 // MaxMem from apiserver is in MB → stored as bytes in URM
+// mbToBytes scales a value that is genuinely in MB to bytes. It applies ONLY
+// to the job submit path where mem_limit is formatted as "<MB> MB"
+// (write.go). Node host max_mem is already in bytes — do NOT scale it.
+const mbToBytes = 1_000_000
 
 // apiEnvelope is the standard top-level response: {"code":200,"msg":"ok","data":...}
 type apiEnvelope struct {

src/frontend/schedulerclient/httpclient_test.go

@@ -0,0 +1,51 @@
+package schedulerclient
+
+import (
+	"context"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+// TestListNodeMemoryBytesKeepsByteUnit verifies the node total memory is NOT
+// re-scaled by the client: the apiserver's `max_mem` field is already in bytes
+// (the worker reads sysinfo().totalram * mem_unit → bytes and passes it through
+// unchanged), so scheduler_list_nodes must report memory_bytes_total ≈ 8.2e9
+// for a ~7.7 GiB node — not the ×1e6-inflated ~8.2e15 that httpclient.go:198
+// produced when it wrongly treated apiserver bytes as MB.
+func TestListNodeMemoryBytesKeepsByteUnit(t *testing.T) {
+	// 8224825344 bytes = the real MemTotal of the t1 node (7.66 GiB).
+	const realMemBytes = 8224825344
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if got := r.Header.Get("Authorization"); got == "" {
+			t.Errorf("expected Authorization header, got empty")
+		}
+		if got := r.URL.Path; got != "/xce/v1/hosts" {
+			t.Errorf("unexpected path %q", got)
+		}
+		w.Header().Set("Content-Type", "application/json")
+		body := `{"code":200,"msg":"ok","data":{"count":1,"rows":[` +
+			`{"fields":["host_name","host_status","num_cpus","num_run","max_mem"],` +
+			`"data":{"host_name":"t1","host_status":"idle","num_cpus":8,"num_run":0,"max_mem":8224825344}}` +
+			`]}}`
+		_, _ = w.Write([]byte(body))
+	}))
+	defer srv.Close()
+
+	hc := NewClient(srv.URL, "xce_ak_test")
+	nodes, err := hc.ListNodes(context.Background())
+	if err != nil {
+		t.Fatalf("ListNodes: %v", err)
+	}
+	if len(nodes) != 1 {
+		t.Fatalf("expected 1 node, got %d", len(nodes))
+	}
+	n := nodes[0]
+	if n.Name != "t1" || n.CoresTotal != 8 {
+		t.Fatalf("unexpected node: %+v", n)
+	}
+	if n.MemoryBytesTotal != realMemBytes {
+		t.Fatalf("MemoryBytesTotal = %d, want %d (apiserver max_mem is already bytes; must not be ×1e6)", n.MemoryBytesTotal, realMemBytes)
+	}
+}

src/frontend/schedulerclient/ordermap_test.go

@@ -56,8 +56,10 @@ func TestOrderMap_RowsUseColumnarShape(t *testing.T) {
 	if n.CoresTotal != 8 {
 		t.Errorf("node.CoresTotal = %d, want 8", n.CoresTotal)
 	}
-	if n.MemoryBytesTotal != 8224821248*mbToBytes {
-		t.Errorf("node.MemoryBytesTotal = %d, want %d", n.MemoryBytesTotal, 8224821248*mbToBytes)
+	// max_mem from apiserver is already bytes (worker reports sysinfo bytes);
+	// the client must NOT scale it by mbToBytes (see httpclient.go ListNodes).
+	if n.MemoryBytesTotal != 8224821248 {
+		t.Errorf("node.MemoryBytesTotal = %d, want %d", n.MemoryBytesTotal, 8224821248)
 	}
 }