A page's time budget is sent to the runtime, and a verb the runtime lacks is told by its code (issue 1966)

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

go/state.go

@@ -4,7 +4,6 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"strings"
 	"time"
 
 	"git.novox.be/novox/mesh-sdk/go/busretry"
@@ -115,15 +114,12 @@ type StatePage struct {
 	Next string `json:"next,omitempty"`
 }
 
-// Page is the current values in key order after the key `after`, as many as fit maxBytes (keys and values), at least
+// Page is the current values in key order after the key `after`, as many as fit maxBytes (keys and values) or the time budget allows, at least
 // one: one request for many values, where Get is one request each. A runtime that does not answer it gives an error
 // satisfying errors.Is(err, errors.ErrUnsupported), and the reader asks Get per key instead.
-func (s KeptState) Page(after string, maxBytes int) (StatePage, error) {
-	raw, err := s.ask("page", map[string]any{"after": after, "max_bytes": maxBytes})
+func (s KeptState) Page(after string, maxBytes int, budget time.Duration) (StatePage, error) {
+	raw, err := s.ask("page", map[string]any{"after": after, "max_bytes": maxBytes, "budget_ms": budget.Milliseconds()})
 	if err != nil {
-		if strings.Contains(err.Error(), "answers no mesh/state.page") {
-			return StatePage{}, fmt.Errorf("%w: %v", errors.ErrUnsupported, err)
-		}
 		return StatePage{}, err
 	}
 	var p StatePage

go/stdio.go

@@ -150,7 +150,12 @@ type refused struct {
 func (r *refused) Error() string { return r.message }
 
 // Is makes a compare-and-set the runtime refused because another writer was first ErrChanged.
-func (r *refused) Is(target error) bool { return target == ErrChanged && r.code == CodeChanged }
+func (r *refused) Is(target error) bool {
+	return target == ErrChanged && r.code == CodeChanged || target == errors.ErrUnsupported && r.code == CodeNoMethod
+}
+
+// CodeNoMethod is the error code the runtime answers a verb it does not have with (JSON-RPC's method not found).
+const CodeNoMethod = -32601
 
 // ErrChanged is a compare-and-set that lost: the key was made or changed by another writer first (novox/hq
 // ADR 0259). Told apart by the runtime's error code, never by its words.

go/views/tools.go

@@ -26,8 +26,8 @@ func (k KeptSource) Get(key string) (*Entry, bool, error) {
 }
 
 // Page is the values after a key in one request (stdio.KeptState.Page), as FirstView prefers them to Get per key.
-func (k KeptSource) Page(after string, maxBytes int) ([]KeyedEntry, string, error) {
-	p, err := k.State.Page(after, maxBytes)
+func (k KeptSource) Page(after string, maxBytes int, budget time.Duration) ([]KeyedEntry, string, error) {
+	p, err := k.State.Page(after, maxBytes, budget)
 	if err != nil {
 		return nil, "", err
 	}

go/views/views.go

@@ -201,10 +201,10 @@ type KeyedEntry struct {
 }
 
 // Pager is a Source that answers many values in one request: the values in key order after a key, as many as fit
-// maxBytes and at least one, and the key to ask after for the rest. FirstView uses it when its source has it, unless
+// maxBytes or the time budget and at least one, and the key to ask after for the rest. FirstView uses it when its source has it, unless
 // it answers errors.Is(err, errors.ErrUnsupported), when it reads per key.
 type Pager interface {
-	Page(after string, maxBytes int) ([]KeyedEntry, string, error)
+	Page(after string, maxBytes int, budget time.Duration) ([]KeyedEntry, string, error)
 }
 
 // FirstView answers one page of state from its owner's source: the mark first, so no change after the revision it
@@ -226,7 +226,7 @@ func FirstView(owner, state string, values, marks Source, after string, now time
 		}
 	}
 	if p, ok := values.(Pager); ok {
-		got, next, err := p.Page(after, PageBytes)
+		got, next, err := p.Page(after, PageBytes, PageBudget)
 		if err == nil {
 			for _, e := range got {
 				a.put(e.Key, e.Entry)

go/views/views_test.go

@@ -676,7 +676,7 @@ func (s *pagedSource) Get(k string) (*Entry, bool, error) {
 	return s.mapSource.Get(k)
 }
 
-func (s *pagedSource) Page(after string, _ int) ([]KeyedEntry, string, error) {
+func (s *pagedSource) Page(after string, _ int, _ time.Duration) ([]KeyedEntry, string, error) {
 	if s.unsupported {
 		return nil, "", errors.ErrUnsupported
 	}