Say an unanswered merge check in its own words, with no action it cannot take (issue 438)

mesh-delivery now says a head whose merge check started and never answered as a
stalled line in state unanswered. Through the generic delivery words it would read
as a delivery and offer a Stop that mesh-delivery refuses, since no delivery of
the head exists; it now names the checks waited on and what the operator can do.

cmd/mesh-controller/plain_words_test.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"encoding/json"
 	"regexp"
 	"strings"
 	"testing"
@@ -347,3 +348,58 @@ func TestAnUnannouncedPullRequestSaysToPushANewCommit(t *testing.T) {
 		t.Fatalf("it reads %q / %q", o.Headline, o.Explanation)
 	}
 }
+
+// **A pull request whose merge check never answered says which check, since when, and what to do** (novox/hq issue
+// 438): mesh-delivery says one as a stalled line in state `unanswered`, the line below exactly as its test makes it.
+// No delivery of the head is held, so there is nothing to stop, release or close: no action is offered, and the
+// operator's acts are a new commit, which asks the check again, or a look at the build seat's queue.
+func TestAnUnansweredMergeCheckSaysWhichCheckAndWhatToDo(t *testing.T) {
+	var l stalledLine
+	if err := json.Unmarshal([]byte(`{"id":"novox/mesh-controller@c11222026a3b","number":212,"state":"unanswered",`+
+		`"waiting":["mesh/merge-gate pending since 2026-10-11T00:11:39Z","mesh/repo-check never set"],"for":"1h1m0s",`+
+		`"bound":"1h0m0s","h2":"none: no delivery of it is held here, so there is none to close — the operator's",`+
+		`"says":"novox/mesh-controller#212 is open on main, which requires the merge check, and its head's check `+
+		`started and never answered: mesh/merge-gate pending since 2026-10-11T00:11:39Z, mesh/repo-check never set. `+
+		`No delivery of it is held here, so nothing asks it again. A new commit on its branch announces it and asks `+
+		`its check"}`), &l); err != nil {
+		t.Fatal(err)
+	}
+	obs := stalledObservations([]stalledLine{l})
+	if len(obs) != 1 || obs[0].Resolver != conditions.ResolverOperator {
+		t.Fatalf("an unanswered merge check is not the operator's: %+v", obs)
+	}
+	o := obs[0]
+	t.Logf("headline: %s\nexplanation: %s\nneeds: %s\nresolved: %s", o.Headline, o.Explanation, o.Needs, o.Resolved)
+	if len(o.Actions) != 0 {
+		t.Fatalf("it offers an action a head with no delivery cannot take: %+v", o.Actions)
+	}
+	if strings.Contains(o.Needs, "stop") || strings.Contains(o.Needs, "release") || !strings.Contains(o.Needs, "commit") ||
+		!strings.Contains(o.Needs, "mesh-controller.queue") {
+		t.Fatalf("it says to %q", o.Needs)
+	}
+	if !strings.Contains(o.Headline, "#212") || !strings.Contains(o.Headline, "merge check") ||
+		strings.Contains(o.Headline, "Delivery of") {
+		t.Fatalf("its headline reads %q", o.Headline)
+	}
+	for _, want := range []string{"mesh/merge-gate pending since 2026-10-11T00:11:39Z", "mesh/repo-check never set",
+		"past its limit of 60 minutes"} {
+		if !strings.Contains(o.Explanation, want) {
+			t.Fatalf("its explanation does not say %q: %q", want, o.Explanation)
+		}
+	}
+	if strings.Contains(o.Explanation, "never asked") || strings.Contains(o.Explanation, "never announced") {
+		t.Fatalf("it says the mesh was never asked, of a head whose check started: %q", o.Explanation)
+	}
+
+	// A line from a mesh-delivery that names no checks still says the check did not answer, and offers nothing.
+	var bare stalledLine
+	if err := json.Unmarshal([]byte(`{"id":"novox/mesh-controller@c11222026a3b","number":212,"state":"unanswered",`+
+		`"for":"1h1m0s","bound":"1h0m0s","h2":"none: no delivery of it is held here, so there is none to close — the operator's"}`),
+		&bare); err != nil {
+		t.Fatal(err)
+	}
+	o = stalledObservations([]stalledLine{bare})[0]
+	if len(o.Actions) != 0 || !strings.Contains(o.Explanation, "has not answered") || strings.Contains(o.Headline, "Delivery of") {
+		t.Fatalf("a line naming no checks reads %q / %q, actions %+v", o.Headline, o.Explanation, o.Actions)
+	}
+}