mesh-issues: carry each value the issues bucket kept, read through the runtime's history, so the log begins with all the bucket still knew (hq ADR 0300 §6, ADR 0307)

modules/mesh-issues/cmd/mesh-issues/changes.go

@@ -464,11 +464,11 @@ func clone(is *Issue) (*Issue, error) {
 	return &c, json.Unmarshal(raw, &c)
 }
 
-// History is a Store that reads every value a key still keeps, oldest first. The carry reads it where the
-// store offers it; the runtime offers no such read today (novox/hq ADR 0300 §6), and then the carry takes
-// each issue's current value, and says so.
+// History is a Store that reads every value a key still keeps, oldest first, as the runtime serves it
+// (novox/hq ADR 0307, mesh-sdk State(...).History): each a put or a delete. The carry reads it where the store
+// offers it, and takes each issue's current value alone where it does not, and says so.
 type History interface {
-	History(state, key string) ([]Entry, error)
+	History(state, key string) ([]stdio.StateRevision, error)
 }
 
 // Carried is what the carry did (ADR 0300 §6).
@@ -479,7 +479,10 @@ type Carried struct {
 	Values  int `json:"values"`
 	Already int `json:"already"`
 	// History says whether each value the bucket kept was carried, or the current value alone.
-	History bool   `json:"history"`
+	History bool `json:"history"`
+	// Deletes is how many deletions among the kept values were passed over: an issue is never deleted by the
+	// tracker, and each value after one holds the issue whole, so the fold needs none.
+	Deletes int    `json:"deletes,omitempty"`
 	Said    string `json:"said"`
 }
 
@@ -560,7 +563,8 @@ func (t *Tracker) carryOne(n uint64) (int, error) {
 }
 
 // kept is every value the bucket keeps of an issue, oldest first, ending with the one read; the current one
-// alone where the store reads no history.
+// alone where the store reads no history. A deletion among them is passed over and counted: the tracker never
+// deletes an issue, the fold has no deletion, and the next value holds the issue whole again.
 func (t *Tracker) kept(n uint64, current *Issue) ([]*Issue, error) {
 	h, ok := t.Store.(History)
 	if !ok {
@@ -572,9 +576,13 @@ func (t *Tracker) kept(n uint64, current *Issue) ([]*Issue, error) {
 	}
 	var out []*Issue
 	for _, e := range old {
+		if e.Op == "delete" {
+			t.carryDeletes.Add(1)
+			continue
+		}
 		var v Issue
 		if json.Unmarshal(e.Value, &v) != nil {
-			t.Logf("[mesh-issues] an older value of issue %d is in a form this module cannot read: not carried", n)
+			t.Logf("[mesh-issues] the value of issue %d at revision %d is in a form this module cannot read: not carried", n, e.Revision)
 			continue
 		}
 		out = append(out, &v)
@@ -609,6 +617,7 @@ func (t *Tracker) Carry() (*Carried, error) {
 	}
 	_, history := t.Store.(History)
 	out := &Carried{History: history}
+	deletes := t.carryDeletes.Load()
 	for _, k := range keys {
 		n, ok := numberOfKey(k)
 		if !ok {
@@ -636,12 +645,17 @@ func (t *Tracker) Carry() (*Carried, error) {
 			out.Already++
 		}
 	}
+	out.Deletes = int(t.carryDeletes.Load() - deletes)
 	switch {
 	case out.Issues == 0:
 		out.Said = fmt.Sprintf("Nothing to carry: the log begins every issue of the bucket (%d).", out.Already)
 	case history:
 		out.Said = fmt.Sprintf("Carried %d values of %d issues into the log, each value the bucket kept, oldest first; "+
 			"%d issues were there already.", out.Values, out.Issues, out.Already)
+		if out.Deletes > 0 {
+			out.Said += fmt.Sprintf(" %d deletions among the kept values were passed over: each value after one holds "+
+				"the issue whole.", out.Deletes)
+		}
 	default:
 		out.Said = fmt.Sprintf("Carried %d issues into the log, %d values: the current value of each, as the runtime "+
 			"reads no older value of a key; %d issues were there already.", out.Issues, out.Values, out.Already)