checker_ask_again: an unread backlog and a recheck ask refuse too (issue 1373, review)

Principle 3: unread is never empty. build_usage's notes refuse; a waiting or held recheck ask refuses like a check ask.

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

modules/mesh-delivery-checker/cmd/mesh-delivery-checker-tools/main.go

@@ -7,6 +7,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"os"
+	"strings"
 	"sync/atomic"
 	"time"
 
@@ -515,10 +516,14 @@ func backlogOf(ask func(string, any) (json.RawMessage, error)) func() ([]check.B
 		}
 		var a struct {
 			Backlog []check.BacklogRow `json:"backlog"`
+			Notes   []string           `json:"notes"`
 		}
 		if err := json.Unmarshal(answer, &a); err != nil {
 			return nil, fmt.Errorf("%s answered what does not decode: %w", buildUsageTool, err)
 		}
+		if len(a.Notes) > 0 { // the backlog was not read: unread is never empty
+			return nil, fmt.Errorf("%s did not read the backlog: %s", buildUsageTool, strings.Join(a.Notes, "; "))
+		}
 		return a.Backlog, nil
 	}
 }

modules/mesh-delivery-checker/cmd/mesh-delivery-checker-tools/main_test.go

@@ -165,6 +165,20 @@ func TestTheToolsServedAreTheFiveReadTools(t *testing.T) {
 			}
 		})
 	}
+	// 1373: the build seats' backlog is read through build_usage; one it says it did not read is never taken for empty.
+	for _, c := range []struct {
+		name, answer string
+		rows         int
+		failed       bool
+	}{
+		{name: "a backlog read", answer: `{"backlog":[{"language":"go","kind":"check","waiting":2}]}`, rows: 1},
+		{name: "a backlog with a note says it was not read", answer: `{"backlog":[],"notes":["the seats' streams cannot be read here"]}`, failed: true},
+	} {
+		rows, err := backlogOf(func(string, any) (json.RawMessage, error) { return json.RawMessage(c.answer), nil })()
+		if (err != nil) != c.failed || len(rows) != c.rows || (c.failed && !strings.Contains(err.Error(), "cannot be read here")) {
+			t.Errorf("1373 backlog, %s: %v, %v", c.name, rows, err)
+		}
+	}
 	// With nothing to read from a tool says so and changes nothing.
 	for _, tl := range Tools(check.Reader{}) {
 		if tl.Name == check.StatusReadTool {

modules/mesh-delivery-checker/internal/check/askagain.go

@@ -255,7 +255,7 @@ type BacklogRow struct {
 	Error    string `json:"error,omitempty"`
 }
 
-// noCheckAskWaits is nil when no check ask waits or is held on any build seat's stream and every row was read; else it
+// noCheckAskWaits is nil when no check or recheck ask waits or is held on any build seat's stream and every row was read; else it
 // names the stream that holds asks. It cannot tell whose ask one is, so any check ask refuses: asking again could run it twice.
 func (r Reader) noCheckAskWaits() error {
 	rows, err := r.Backlog()
@@ -263,7 +263,7 @@ func (r Reader) noCheckAskWaits() error {
 		return fmt.Errorf("the build seats' streams cannot be read (%v), so whether an ask of the check waits in one cannot be told; asking again could run it twice", err)
 	}
 	for _, row := range rows {
-		if row.Kind != "check" {
+		if row.Kind != "check" && row.Kind != "recheck" { // both kinds are the checker's asks (judge.go)
 			continue
 		}
 		if row.Error != "" {

modules/mesh-delivery-checker/internal/check/lostask_test.go

@@ -340,6 +340,8 @@ func TestACheckWhoseAskJudgedNothingIsAskedAgainOrRead(t *testing.T) {
 						bad  string
 					}{{"a check ask waits", []BacklogRow{{Language: "go", Kind: "check", Waiting: 1}}, "holds asks"},
 						{"a check ask is held", []BacklogRow{{Language: "go", Kind: "check", Held: 1}}, "holds asks"},
+						{"a recheck ask waits", []BacklogRow{{Language: "go", Kind: "recheck", Waiting: 1}}, "holds asks"},
+						{"a recheck ask is held", []BacklogRow{{Language: "go", Kind: "recheck", Held: 1}}, "holds asks"},
 						{"a stream cannot be read", []BacklogRow{{Language: "go", Kind: "check", Error: "no worker"}}, "cannot be read"},
 						{"only a delivery ask waits", []BacklogRow{{Language: "go", Kind: "delivery", Waiting: 3}}, ""}} {
 						noAsk.Backlog = func() ([]BacklogRow, error) { return c.rows, nil }