Research efforts can be ideas, and at most three are active (issue 1970, ADR 0629)

The roadmap lives in the knowledge base: an idea is listed, never served as in force; propose refuses a further active effort.

Claude-Session: https://claude.ai/code/session_01JG73KG7AfSdh6FP8VrBqCn

modules/mesh-knowledge/cmd/mesh-knowledge/kb.go

@@ -11,6 +11,7 @@ import (
 	"errors"
 	"fmt"
 	"regexp"
+	"sort"
 	"strconv"
 	"strings"
 	"sync"
@@ -53,8 +54,14 @@ type Settings struct {
 	// ReservedFor is how long a reserved number waits for its proposal before it is withdrawn, as a duration
 	// such as 168h; DefaultReservedFor when empty.
 	ReservedFor string `json:"reserved-for,omitempty"`
+	// ResearchActiveAtMost is the most research efforts that may be active at once (ADR 0629); DefaultResearchActiveAtMost
+	// when absent or 0.
+	ResearchActiveAtMost int `json:"research-active-at-most,omitempty"`
 }
 
+// DefaultResearchActiveAtMost is how many research efforts may be active at once unless the settings say otherwise.
+const DefaultResearchActiveAtMost = 3
+
 // DefaultReservedFor is how long a reservation waits for its proposal unless the settings say otherwise.
 const DefaultReservedFor = 7 * 24 * time.Hour
 
@@ -248,7 +255,7 @@ type ProposeAsk struct {
 	NeedsOperator bool
 	// Brief is what the operator's ask shows (novox/hq issue 639).
 	Brief *Brief
-	// Status is a research effort's: active, graduated or abandoned.
+	// Status is a research effort's: active, graduated, abandoned or idea.
 	Status string
 	// Insight, for an accepted record, is what stood before: the proposal is a progressive insight.
 	Insight string
@@ -348,7 +355,7 @@ func (k *KB) Propose(caller string, a ProposeAsk) (*Proposed, error) {
 			}
 			// An active research effort is still being researched: it takes new versions freely, each reviewed as a
 			// proposal while the served version stays (novox/hq issue 844). Every other accepted record needs an insight.
-			revision := a.Kind == KindResearch && held.Current.Status == StatusActive && strings.TrimSpace(a.Insight) == ""
+			revision := a.Kind == KindResearch && (held.Current.Status == StatusActive || held.Current.Status == StatusIdea) && strings.TrimSpace(a.Insight) == ""
 			if strings.TrimSpace(a.Insight) == "" && !revision {
 				return nil, fmt.Errorf("%s is %s: it changes only by a new record, or by a progressive insight, a correction of fact "+
 					"that leaves the decision standing (give insight: what stood before). Nothing was proposed", key, held.Current.Status)
@@ -390,6 +397,11 @@ func (k *KB) Propose(caller string, a ProposeAsk) (*Proposed, error) {
 	if !current && a.Kind == KindResearch && r.Effort == "" {
 		r.Effort = held.Current.Status
 	}
+	if a.Kind == KindResearch && r.Effort == StatusActive {
+		if why := k.activeLimitRefusal(ctx, key); why != "" {
+			refusals = append(refusals, Refusal{Rule: "research-active-at-most", Says: why})
+		}
+	}
 	// A new version of an active effort is new text: the dated rules hold it from the day it is proposed, while the
 	// record keeps its own date (novox/hq issue 844).
 	day := r.Date
@@ -434,6 +446,36 @@ func (k *KB) Propose(caller string, a ProposeAsk) (*Proposed, error) {
 	return &Proposed{Record: key.String(), Version: n, Status: StatusProposed, Says: says + "."}, nil
 }
 
+// activeLimitRefusal (ADR 0629 §4, a check of the record set beside the one-record rules of ADR 0290 §4) says why a research effort may not be active now: the limit of efforts other than this one
+// already active (accepted at active, or proposed at active and waiting for review) is reached (ADR 0629). Empty
+// when it may.
+func (k *KB) activeLimitRefusal(ctx context.Context, key Key) string {
+	limit := k.settings().ResearchActiveAtMost
+	if limit <= 0 {
+		limit = DefaultResearchActiveAtMost
+	}
+	all, err := k.Store.All(ctx)
+	if err != nil {
+		return fmt.Sprintf("the active efforts cannot be counted (%v)", err)
+	}
+	var names []string
+	for _, e := range all {
+		if e.Current == nil || e.Current.Kind != KindResearch || e.Current.Key() == key {
+			continue
+		}
+		w := e.Working()
+		if e.Current.Status == StatusActive || (w != nil && w.Effort == StatusActive && (w.Status == StatusProposed || e.Pending != nil)) {
+			names = append(names, fmt.Sprintf("%s (%s)", e.Current.Key(), e.Current.Title))
+		}
+	}
+	if len(names) < limit {
+		return ""
+	}
+	sort.Strings(names)
+	return fmt.Sprintf("at most %d research efforts are active and %d already are: %s. Park one as an idea first, or propose this one as an idea",
+		limit, len(names), strings.Join(names, "; "))
+}
+
 // ---- acceptance ------------------------------------------------------------------------------------------
 
 // accept makes a reviewed version the one served: accepted, its clauses in force, every clause and record it