The way back: a node whose placement key is deleted returns to the controller's compositions without a restart, says so in its journal and its have, and answers such a candidate as returning; pin mesh-sdk 472d5f3 (issue 1126, the seed's revert)

The seed's revert (mesh-catalog #526) was refused on 'would stop running node',
while a self-composing node would have refused its placement's absence, kept
what runs and marked every have failed until a restart. endWhenUnplaced ends the
agent's run when the key goes, so it begins again on the controller's
compositions, as at a start without a key; the composer refuses nothing while
unplaced; the node's have says whose compositions it applies (Composes); the
shadow answers a deleted placement Returns, verdict same.

internal/selfcompose/selfcompose.go

@@ -429,9 +429,16 @@ func (c *Composer) compose(ctx context.Context) []agent.Update {
 	_, nodeWanted := c.wants[agent.NodeModule]
 	// What it runs inside its own composition and no want names at a build of the new form stays there, as the
 	// controller's composed writer folds it (issue 1126); compose folds none a want names.
-	inOwn := c.inOwnOf(c.placements[c.env.Node])
+	own, placed := c.placements[c.env.Node]
+	inOwn := c.inOwnOf(own)
 	r := reader{c: c}
 	c.mu.Unlock()
+	if !placed {
+		// The catalogue no longer places it: the agent returns to the controller's compositions (endWhenUnplaced), and
+		// this is no refusal of what it runs (issue 1126, the seed's revert).
+		c.sayOnce("the catalogue no longer places this node: it composes nothing of its own, and keeps running what it runs")
+		return nil
+	}
 	// Composed from the build its want names (frombus.Scope.KeptAt, issue 1126).
 	for _, module := range behind {
 		kept[module] = fps[module]