R-1 rest, R-12, R-13: the capability words are mesh-sdk's, the ledger's fill and removal are answered, the artifact states the words

sent-get is under sent-objects-calls; mesh/ledger.fill answers the history's fill against its cap and mesh/ledger.remove
removes an instance's operations, snapshot, state and index entries, both under ledger-upkeep-calls; the runtime artifact's
`states` is exactly the words the runner states.

Builds: design 47 G §462, §488, §545, §587, §622, §155

Claude-Session: https://claude.ai/code/session_01NcbgfGKaxw984XyAPfLm4h

node-tools/internal/ledger/memory.go

@@ -1,9 +1,12 @@
 package ledger
 
 import (
+	"errors"
 	"sort"
 	"strings"
 	"sync"
+
+	"git.novox.be/novox/mesh-sdk/go/buscalls"
 )
 
 // The memory stores keep what the bus keeps, as the bus answers it, for a test of a ledger without a bus: a stream whose
@@ -12,9 +15,13 @@ import (
 
 // MemoryHistory is a history in memory.
 type MemoryHistory struct {
-	mu   sync.Mutex
-	seq  uint64
-	kept []struct {
+	// MaxBytes is the cap its fill is said against.
+	MaxBytes uint64
+	// FillFails makes Fill an error, as a store that cannot say its fill.
+	FillFails bool
+	mu        sync.Mutex
+	seq       uint64
+	kept      []struct {
 		key string
 		Kept
 	}
@@ -73,6 +80,32 @@ func (h *MemoryHistory) Read(keys string, from uint64, limit int) ([]Kept, error
 	return out, nil
 }
 
+func (h *MemoryHistory) Purge(key string) error {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	kept := h.kept[:0]
+	for _, k := range h.kept {
+		if k.key != key {
+			kept = append(kept, k)
+		}
+	}
+	h.kept = kept
+	return nil
+}
+
+func (h *MemoryHistory) Fill() (buscalls.Fill, error) {
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	if h.FillFails {
+		return buscalls.Fill{}, errors.New("the history does not say its fill")
+	}
+	f := buscalls.Fill{Count: uint64(len(h.kept)), MaxBytes: h.MaxBytes}
+	for _, k := range h.kept {
+		f.Bytes += uint64(len(k.Data))
+	}
+	return f, nil
+}
+
 // Expire drops every operation of the history, as a ledger's keeping days end them.
 func (h *MemoryHistory) Expire() {
 	h.mu.Lock()
@@ -129,6 +162,13 @@ func (s *MemoryState) Keys() ([]string, error) {
 	return out, nil
 }
 
+func (s *MemoryState) Delete(key string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	delete(s.kv, key)
+	return nil
+}
+
 // MemorySnapshots are snapshots in memory.
 type MemorySnapshots struct {
 	mu sync.Mutex
@@ -157,6 +197,13 @@ func (s *MemorySnapshots) Put(key string, value []byte, expect uint64) error {
 	return nil
 }
 
+func (s *MemorySnapshots) Purge(key string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	delete(s.kv, key)
+	return nil
+}
+
 // MemoryIndex is an index's bucket in memory.
 type MemoryIndex struct {
 	mu sync.Mutex