diff --git a/cmd/mesh-builder/tried_test.go b/cmd/mesh-builder/tried_test.go
new file mode 100644
index 00000000..06aaf706
--- /dev/null
+++ b/cmd/mesh-builder/tried_test.go
@@ -0,0 +1,31 @@
+package main
+
+import (
+	"testing"
+	"time"
+
+	"github.com/novox/mesh-controller/internal/builder"
+)
+
+// A try's outcome, as the build seat says it in the build's log (novox/hq issue 686): the repository's own
+// check's verdict, how long it took, and each line naming what failed.
+func TestATrysOutcomeNamesWhatFailed(t *testing.T) {
+	tried := triedOf(builder.CheckVerdict{Verdict: "pass", Summary: "the change touches no module", Took: 303 * time.Second,
+		Head: "c0ffee", Trunk: "ca3f43c", Gate: &builder.Layer{Verdict: "pass"},
+		Repo: &builder.Layer{Verdict: "fail", Summary: "its merge-check.sh failed: TestX",
+			Failed: "--- FAIL: TestX (0.01s)\n    x_test.go:12: got 1, want 2"}})
+	if tried.Verdict != "fail" || tried.Took != "5m3s" || len(tried.Failed) != 2 || tried.Trunk != "ca3f43c" ||
+		tried.Summary != "its merge-check.sh failed: TestX" {
+		t.Fatalf("a failed try: %+v", tried)
+	}
+	// A head that does not merge fails both layers: the check's own word.
+	conflict := triedOf(builder.CheckVerdict{Verdict: "fail", Summary: "does not merge", Gate: &builder.Layer{Verdict: "fail"},
+		Repo: &builder.Layer{Verdict: "fail", Summary: "does not merge"}})
+	if conflict.Verdict != "fail" || conflict.Summary != "does not merge" {
+		t.Fatalf("a try that does not merge: %+v", conflict)
+	}
+	// No verdict is an error, never a pass.
+	if none := triedOf(builder.CheckVerdict{}); none.Verdict != "error" {
+		t.Fatalf("a try with no verdict: %+v", none)
+	}
+}
diff --git a/cmd/mesh-controller/try_test.go b/cmd/mesh-controller/try_test.go
new file mode 100644
index 00000000..01bc05c9
--- /dev/null
+++ b/cmd/mesh-controller/try_test.go
@@ -0,0 +1,162 @@
+package main
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"reflect"
+	"strings"
+	"testing"
+
+	"github.com/novox/mesh-controller/internal/catalogue"
+	"github.com/novox/mesh-controller/internal/link"
+)
+
+// A branch is tried before its pull request (novox/hq issue 686): the repository's own check asked for a pushed
+// branch or commit, with no pull request.
+
+// What a try asks is a check — after deliveries in the build queue, bounded as one — of the repository's own
+// script alone: no module of the graph, so no gate; nothing built for a merge, so no reusable image.
+func TestATryAsksACheckOfTheRepositorysOwnScriptAlone(t *testing.T) {
+	request := link.BuildRequest{ID: "build-1", Ref: "c0ffee", Check: &link.CheckRequest{Owner: "novox", Repo: "a",
+		Number: 7, Base: "main", Modules: []string{"a"}, New: []string{"b"}, Manifests: []string{"module.json"},
+		Dependents: []string{"c"}, Builds: []link.CheckBuild{{Module: "a"}}, Judge: link.JudgeSelf,
+		Plan: &link.ChangePlan{}}}
+	tried := asATry(request, "^TestStore", true)
+	c := tried.Check
+	if !c.Try || c.Number != 0 || c.Tests != "^TestStore" || !c.StoreOnly {
+		t.Fatalf("not marked a try, or it kept a pull request's number: %+v", c)
+	}
+	if len(c.Modules)+len(c.New)+len(c.Manifests)+len(c.Dependents)+len(c.Builds) != 0 || c.Judge != "" || c.Plan != nil {
+		t.Fatalf("a try runs the gate or builds for a merge: %+v", c)
+	}
+	if c.Base != "main" || c.Owner != "novox" || tried.Ref != "c0ffee" {
+		t.Fatalf("a try lost what it merges into what: %+v", tried)
+	}
+	if link.KindOf(tried) != link.KindCheck {
+		t.Fatal("a try does not count as a check in the build queue")
+	}
+}
+
+// A try's outcome is heard and left there: no `checked` is said, so the forge's holder sets no status, and
+// nothing is recorded or registered (the handler holds no store here, and would fail reaching for one).
+func TestATrysOutcomeSetsNoStatusAndRegistersNothing(t *testing.T) {
+	said := &saidOnTheBus{}
+	checkEvents = said
+	defer func() { checkEvents = nil }()
+	for name, result := range map[string]link.BuildResult{
+		"a try": {ID: "build-1", Ref: "c0ffee", Checked: &link.CheckRequest{Owner: "novox", Repo: "a", Try: true},
+			Check: &link.CheckOutcome{Verdict: "pass", RepoCheck: &link.CheckLayer{Verdict: "fail", Summary: "failed"}}},
+		"a try that could not run": {ID: "build-2", Checked: &link.CheckRequest{Owner: "novox", Repo: "a", Try: true},
+			Failed: "cannot clone"},
+		// A build seat from before the mark echoes the ask without it: a check of no pull request and no
+		// group is still nobody's status.
+		"a try echoed by an older build seat": {ID: "build-3", Checked: &link.CheckRequest{Owner: "novox", Repo: "a"},
+			Check: &link.CheckOutcome{Verdict: "pass"}},
+	} {
+		if err := (builds{}).Built(context.Background(), result); err != nil {
+			t.Fatalf("%s: %v", name, err)
+		}
+	}
+	if len(said.events) != 0 {
+		t.Fatalf("a try's outcome was said for the forge: %v", said.events)
+	}
+	// A pull request's check is still said.
+	_ = (builds{}).Built(context.Background(), link.BuildResult{ID: "build-4", Checked: &link.CheckRequest{
+		Owner: "novox", Repo: "a", Number: 7}, Check: &link.CheckOutcome{Verdict: "pass"}})
+	if len(said.events) != 1 {
+		t.Fatalf("a pull request's check was said %d time(s)", len(said.events))
+	}
+}
+
+// saidOnTheBus keeps the seat events said, and nothing else.
+type saidOnTheBus struct {
+	link.Bus
+	events []string
+}
+
+func (s *saidOnTheBus) PublishSeatEvent(_ context.Context, seat, event string, _ []byte) error {
+	s.events = append(s.events, seat+" "+event)
+	return nil
+}
+
+// A ref the forge does not hold is refused before anything is asked, naming it.
+func TestATryOfAnUnknownRefIsRefusedLoudly(t *testing.T) {
+	was := forgeCommit
+	defer func() { forgeCommit = was }()
+	forgeCommit = func(_ context.Context, owner, repo, ref string) (string, string, error) {
+		return "", "", errors.New("404 object does not exist [id: " + ref + "]")
+	}
+	err := tryCommand(context.Background(), []string{"novox/mesh-controller", "fix/no-such-branch"})
+	if err == nil {
+		t.Fatal("a try of a ref the forge does not hold was asked")
+	}
+	for _, want := range []string{"fix/no-such-branch", "novox/mesh-controller", "nothing was asked", "404"} {
+		if !strings.Contains(err.Error(), want) {
+			t.Errorf("the refusal does not say %q: %v", want, err)
+		}
+	}
+	for _, args := range [][]string{{"mesh-controller", "main"}, {"novox/mesh-controller"}, {"novox/a", "--upload-pack=x"},
+		{"novox/a", "main", "--tests", "x; rm -rf /"}, {"novox/a", "main", "--id", "build-1"}} {
+		if err := tryCommand(context.Background(), args); err == nil {
+			t.Errorf("try %v was taken", args)
+		}
+	}
+}
+
+// The answer of a try carries the lines that name what failed (novox/hq issue 460's shape) and how long it took.
+func TestATrysAnswerCarriesTheFailingLines(t *testing.T) {
+	tried, _ := json.Marshal(link.Tried{Verdict: "fail", Summary: "its merge-check.sh failed: TestX", Took: "5m3s",
+		Head: "c0ffee", Trunk: "ca3f43c", Failed: []string{"--- FAIL: TestX (0.01s)", "    x_test.go:12: got 1, want 2",
+			"FAIL\tgithub.com/novox/a/cmd\t3.1s"}})
+	lines := []link.BuildLine{{Seq: 1, Step: "check", Message: "novox/a#0 at c0ffee"},
+		{Seq: 2, Step: "output", Message: "ok  	github.com/novox/a/internal	1.2s"},
+		{Seq: 3, Step: link.StepTried, Message: string(tried)}, {Seq: 4, Step: "checked", Message: "pass: x"}}
+	a := tryAnswerOf("build-1", lines)
+	if a.State != "fail" || a.Took != "5m3s" || len(a.Failed) != 3 || a.Failed[0] != "--- FAIL: TestX (0.01s)" ||
+		a.Trunk != "ca3f43c" || a.ID != "build-1" {
+		t.Fatalf("the answer lost the verdict, the time or the failing lines: %+v", a)
+	}
+	// Not answered yet: said as running, with how far it is — never as a pass.
+	if a := tryAnswerOf("build-1", lines[:2]); a.State != "running" || a.Last == "" {
+		t.Fatalf("a try still running: %+v", a)
+	}
+	if a := tryAnswerOf("build-1", nil); a.State != "waiting" {
+		t.Fatalf("a try nothing was said of: %+v", a)
+	}
+	// One that could not run is an error with the build seat's word, never a pass.
+	if a := tryAnswerOf("build-1", append(lines[:1:1], link.BuildLine{Seq: 2, Step: "failed",
+		Message: "cannot clone"})); a.State != "error" || !strings.Contains(a.Said, "cannot clone") {
+		t.Fatalf("a try that could not run: %+v", a)
+	}
+}
+
+// The verb runs its command, and is declared with the shell habit it replaces (novox/hq ADR 0245).
+func TestTheTryVerbRunsItsCommand(t *testing.T) {
+	for _, c := range []struct {
+		args map[string]any
+		want []string
+	}{
+		{map[string]any{"repository": "novox/a", "ref": "fix/x"}, []string{"try", "novox/a", "fix/x"}},
+		{map[string]any{"repository": "novox/a", "ref": "fix/x", "base": "main", "tests": "^TestX$", "store-only": "true"},
+			[]string{"try", "novox/a", "fix/x", "--base", "main", "--tests", "^TestX$", "--store-only"}},
+		{map[string]any{"id": "build-1"}, []string{"try", "--id", "build-1"}},
+	} {
+		got, err := argvFor("try", c.args)
+		if err != nil || !reflect.DeepEqual(got, c.want) {
+			t.Errorf("try %v: %v %v, want %v", c.args, got, err, c.want)
+		}
+	}
+	if _, err := argvFor("try", map[string]any{"repository": "novox/a"}); err == nil {
+		t.Error("a try of no ref was taken")
+	}
+	for _, v := range catalogue.ControllerVerbs {
+		if v.Name == "try" {
+			if len(v.Replaces) == 0 {
+				t.Error("try names no shell habit it replaces")
+			}
+			return
+		}
+	}
+	t.Error("try is not a verb of the controller seat")
+}
diff --git a/internal/builder/check_test.go b/internal/builder/check_test.go
index 92583f5a..1eb5890a 100644
--- a/internal/builder/check_test.go
+++ b/internal/builder/check_test.go
@@ -590,3 +590,15 @@ func TestARepositoryInTwoLanguagesIsCheckedInBoth(t *testing.T) {
 		t.Errorf("a part in a toolchain the mesh does not hold answered %+v — never a pass", layer)
 	}
 }
+
+// A branch tried before its pull request may narrow what the repository's script runs (novox/hq issue 686); a
+// pull request's check is handed nothing, and runs whole.
+func TestOnlyATrysSelectionReachesTheScript(t *testing.T) {
+	if env := selection(CheckSpec{Number: 7}); len(env) != 0 {
+		t.Fatalf("a pull request's check was handed a selection: %v", env)
+	}
+	env := selection(CheckSpec{Tests: "^TestX$", StoreOnly: true})
+	if len(env) != 2 || env[0] != "MESH_CHECK_TESTS=^TestX$" || env[1] != "MESH_CHECK_STORE_ONLY=1" {
+		t.Fatalf("a try's selection: %v", env)
+	}
+}