A module depends on the node seats that apply its resources (hq ADR 0207)

Seed node-package-manager and node-container-runtime. Derive each module's
dependencies from its declared service, package and container resources;
judge them over the node's whole set, exempting the foundation. Refuse at
assign (several modules may go on as one act) and at unassign of the last
holder; report at composition in status, behind one switch.

cmd/mesh-controller/plan.go

@@ -10,6 +10,7 @@ import (
 	"os"
 	"sort"
 	"strings"
+	"sync"
 
 	"github.com/novox/mesh-controller/internal/broker"
 	"github.com/novox/mesh-controller/internal/catalogue"
@@ -127,6 +128,7 @@ func planFor(ctx context.Context, open *stores, nodeName string) (catalogue.Reso
 		// a mesh-wide gatherer may pass over — see notResolvable.
 		return catalogue.Resolution{}, nil, notResolvable{err}
 	}
+	logUnheld(nodeName, resolved.Unheld)
 
 	// The credential for each thing this node takes from elsewhere. Made once and kept, so the
 	// password a provider is told to create is the one its consumer was given — and sealed to
@@ -1325,3 +1327,34 @@ func providerModuleOf(resolved catalogue.Resolution, open *stores, ctx context.C
 	}
 	return ""
 }
+
+// unheldLogged is what was last logged about each node's unmet seat dependencies, so the log says
+// each change once (novox/hq ADR 0207), on stderr so `status --json` stays a document — planFor runs for every status, push and assignment, and a
+// line per call would bury the one that changed.
+var (
+	unheldLogged   = map[string]string{}
+	unheldLoggedMu sync.Mutex
+)
+
+// logUnheld logs a node's unmet seat dependencies when they differ from what was last logged for
+// it, including when they become none.
+func logUnheld(node string, unheld []catalogue.Unheld) {
+	lines := make([]string, 0, len(unheld))
+	for _, u := range unheld {
+		lines = append(lines, u.String())
+	}
+	now := strings.Join(lines, "\n")
+	unheldLoggedMu.Lock()
+	before, seen := unheldLogged[node]
+	unheldLogged[node] = now
+	unheldLoggedMu.Unlock()
+	if (seen && before == now) || (!seen && now == "") {
+		return
+	}
+	if now == "" {
+		fmt.Fprintf(os.Stderr, "%s: every seat its modules depend on is held (novox/hq ADR 0207)\n", node)
+		return
+	}
+	fmt.Fprintf(os.Stderr, "%s: %d unmet seat dependenc(ies), reported and not refused (novox/hq ADR 0207):\n  %s\n",
+		node, len(lines), strings.Join(lines, "\n  "))
+}