The composition verb says what holds each held module and the build it would be composed at (issue 1921, milestone 47/G H4)

The node's own composition named a held module's why only; it now also says whether its manifest's verdict or this
node-engine's decoder holds it, and at which build, as the input a check's composer reads says it. Said in the held
words, so the node-engine seat's answer keeps its shape.

Claude-Session: https://claude.ai/code/session_01NcbgfFSnn24M3GcqttoU7i

internal/selfcompose/selfcompose.go

@@ -235,6 +235,9 @@ type Pass struct {
 	Refused string `json:"refused,omitempty"`
 	// Held is each module refused alone, with why.
 	Held map[string]string `json:"held,omitempty"`
+	// holds is what holds each module Held names by its manifest's verdict or its decoder, with the build it would be
+	// composed at (frombus.Scope.Holds), for LastHeld's words.
+	holds map[string]compose.Hold
 	// Handed is how many compositions the pass handed the agent that differ from what it handed before.
 	Handed int `json:"handed"`
 	// Again is when the node composes again on its own, after a seat or a read that did not answer; zero when it does
@@ -247,11 +250,34 @@ type Pass struct {
 	Queued string `json:"queued,omitempty"`
 }
 
-// LastHeld is what the last pass held, each module with why; nil before a pass or when it held none.
+// LastHeld is what the last pass held, each module with why: for one its manifest's verdict or its decoder holds, also
+// that and the build it would be composed at, as the input a check's composer reads says it (compose.Input.Holds,
+// issue 1921); nil before a pass or when it held none.
 func (c *Composer) LastHeld() map[string]string {
 	c.mu.Lock()
 	defer c.mu.Unlock()
-	return maps.Clone(c.last.Held)
+	out := maps.Clone(c.last.Held)
+	for name, h := range c.last.holds {
+		if why, held := out[name]; held {
+			out[name] = why + " (" + holdWords(h) + ")"
+		}
+	}
+	return out
+}
+
+// holdWords is what holds a module and the build it would be composed at, in words.
+func holdWords(h compose.Hold) string {
+	by := "held by " + h.By
+	switch h.By {
+	case compose.HeldByVerdict:
+		by = "held by its manifest's verdict"
+	case compose.HeldByDecoder:
+		by = "held by this node-engine's decoder"
+	}
+	if h.Build == "" {
+		return by + ", at no build"
+	}
+	return by + ", at the build " + h.Build
 }
 
 // askedWithin is how recent a pass answers an ask of the verb compose without a new one: the first wait after a seat
@@ -919,6 +945,7 @@ func (c *Composer) compose(ctx context.Context) []agent.Update {
 	// module's have, from which the watchman raises its condition.
 	keptRuns := map[string][]string{}
 	var keptMu sync.Mutex
+	var holds map[string]compose.Hold
 	scope := frombus.Scope{Node: c.env.Node, KeptAt: kept, InOwn: inOwn, Running: running, Kept: func(module, words string) {
 		keptMu.Lock()
 		defer keptMu.Unlock()
@@ -926,7 +953,7 @@ func (c *Composer) compose(ctx context.Context) []agent.Update {
 			keptRuns[module] = append(keptRuns[module], words)
 		}
 		c.sayOnceEach(words)
-	}}
+	}, Holds: func(h map[string]compose.Hold) { holds = h }}
 	c.mu.Lock()
 	c.dataScope = frombus.Scope{Node: c.env.Node, KeptAt: kept, InOwn: inOwn} // the data items are worked out as composed
 	c.mu.Unlock()
@@ -985,7 +1012,7 @@ func (c *Composer) compose(ctx context.Context) []agent.Update {
 		return nil
 	}
 	c.paid()
-	pass.Held = held
+	pass.Held, pass.holds = held, holds
 	// The provisioner client's account the node runs with, dropped by this pass, is said: every filled write is refused
 	// under a declaration that names none (filling.JudgeAccount), and no module is handed to it (issue 774, ace,
 	// 2026-11-04 01:29). A placed client keeps its account while it is held (compose.Node.RunningProvisioner).