diff --git a/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/main.go b/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/main.go
index b873b4c2..407f642c 100644
--- a/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/main.go
+++ b/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/main.go
@@ -7,8 +7,10 @@ package main
 import (
 	"cmp"
 	"context"
+	"errors"
 	"fmt"
 	"io"
+	"io/fs"
 	"log"
 	"maps"
 	"os"
@@ -200,13 +202,9 @@ func run(ctx context.Context, getenv func(string) string, logOut io.Writer) erro
 	b.Numbers = build.VersionNumbers{N: numberer}
 	// The builder's toolchain waits (design 47 G §672): its state waits, and wait-held and wait-ended on its stream waits; its
 	// bound is its setting toolchain-wait-minutes.
-	waitBound := defaultToolchainWait
-	if v := strings.TrimSpace(getenv("MESH_BUILDER_TOOLCHAIN_WAIT_MINUTES")); v != "" {
-		n, err := strconv.Atoi(v)
-		if err != nil || n < 1 {
-			return fmt.Errorf("MESH_BUILDER_TOOLCHAIN_WAIT_MINUTES %q is not a number of minutes", v)
-		}
-		waitBound = time.Duration(n) * time.Minute
+	waitBound, err := toolchainWaitOf(getenv("MESH_BUILDER_TOOLCHAIN_WAIT_FILE"))
+	if err != nil {
+		return err
 	}
 	waitsBucket := process.AwaitBucket(ctx, js, conn, build.WaitsBucket, "the toolchain waits are kept in memory only, and builder_waits shows none", logger.Printf)
 	b.Waits = newWaitsKept(waitsBucket, func(ctx context.Context, event, id string, body any) error {
@@ -569,3 +567,28 @@ func (s *sourceHeads) head(_ context.Context, rev uint64, repository string) (st
 	}
 	return "", nil
 }
+
+// toolchainWaitOf reads the toolchain wait's setting, toolchain-wait-minutes, from the file the manifest declares with the
+// content ${config:toolchain-wait-minutes} (design 47 G §672, A-71), at the builder's start: no file, or an empty one, is
+// the default; a content that is no number of minutes is an error naming the file.
+func toolchainWaitOf(path string) (time.Duration, error) {
+	if path == "" {
+		return defaultToolchainWait, nil
+	}
+	raw, err := os.ReadFile(path)
+	if errors.Is(err, fs.ErrNotExist) {
+		return defaultToolchainWait, nil
+	}
+	if err != nil {
+		return 0, err
+	}
+	v := strings.TrimSpace(string(raw))
+	if v == "" {
+		return defaultToolchainWait, nil
+	}
+	n, err := strconv.Atoi(v)
+	if err != nil || n < 1 {
+		return 0, fmt.Errorf("%s holds %q, which is not a number of minutes", path, v)
+	}
+	return time.Duration(n) * time.Minute, nil
+}
diff --git a/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/toolchainwait_test.go b/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/toolchainwait_test.go
new file mode 100644
index 00000000..2d63b4ab
--- /dev/null
+++ b/modules/mesh-delivery-builder/cmd/mesh-delivery-builder/toolchainwait_test.go
@@ -0,0 +1,39 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+// A-71: the toolchain wait's setting is read at the start from the file the manifest declares, never from the environment.
+func TestToolchainWaitIsReadFromItsFile(t *testing.T) {
+	dir := t.TempDir()
+	n := 0
+	file := func(content string) string {
+		n++
+		p := filepath.Join(dir, "w"+string(rune('a'+n)))
+		if err := os.WriteFile(p, []byte(content), 0o600); err != nil {
+			t.Fatal(err)
+		}
+		return p
+	}
+	for _, c := range []struct {
+		name, path string
+		want       time.Duration
+		bad        bool
+	}{
+		{"no file named", "", defaultToolchainWait, false},
+		{"file absent", filepath.Join(dir, "absent"), defaultToolchainWait, false},
+		{"empty", file(" \n"), defaultToolchainWait, false},
+		{"minutes", file("15\n"), 15 * time.Minute, false},
+		{"not a number", file("soon"), 0, true},
+		{"zero", file("0"), 0, true},
+	} {
+		got, err := toolchainWaitOf(c.path)
+		if (err != nil) != c.bad || got != c.want {
+			t.Errorf("%s: %v, %v; want %v, error %v", c.name, got, err, c.want, c.bad)
+		}
+	}
+}
diff --git a/modules/mesh-delivery-builder/manifest_test.go b/modules/mesh-delivery-builder/manifest_test.go
index 835fd25d..38debdc3 100644
--- a/modules/mesh-delivery-builder/manifest_test.go
+++ b/modules/mesh-delivery-builder/manifest_test.go
@@ -3,6 +3,7 @@ package manifest
 import (
 	"bytes"
 	"encoding/json"
+	"fmt"
 	"io/fs"
 	"os"
 	"path/filepath"
@@ -221,8 +222,22 @@ func TestManifestProcess(t *testing.T) { // 1607/AC1
 		t.Errorf("process = %v", p)
 	}
 	env, _ := p["env"].(map[string]any)
-	if len(env) != 2 || env["MESH_BROKER_FILE"] != "${dir:state}/broker" || env["MESH_BUILDER_TOOLCHAIN_WAIT_MINUTES"] != "${config:toolchain-wait-minutes}" {
-		t.Errorf("env = %v, want the broker file and the toolchain wait's setting (design 47 G §672)", p["env"])
+	if len(env) != 2 || env["MESH_BROKER_FILE"] != "${dir:state}/broker" || env["MESH_BUILDER_TOOLCHAIN_WAIT_FILE"] != "${dir:state}/toolchain-wait-minutes" {
+		t.Errorf("env = %v, want the broker file and the path of the toolchain wait's file, never the setting itself (design 47 G §672, A-71)", p["env"])
+	}
+	for k, v := range env {
+		if strings.Contains(fmt.Sprint(v), "${config:") {
+			t.Errorf("env %s = %v: a setting reaches the process as a file, never its environment (A-71)", k, v)
+		}
+	}
+	found := false
+	for _, r := range m.Resources {
+		if r["type"] == "file" && r["path"] == "${dir:state}/toolchain-wait-minutes" && r["content"] == "${config:toolchain-wait-minutes}" {
+			found = true
+		}
+	}
+	if !found {
+		t.Errorf("no file resource with the content ${config:toolchain-wait-minutes}: A-71")
 	}
 	for _, r := range m.Resources {
 		if r["id"] == "settings" {
diff --git a/modules/mesh-delivery-builder/module.json b/modules/mesh-delivery-builder/module.json
index e43d5995..8e65cc39 100644
--- a/modules/mesh-delivery-builder/module.json
+++ b/modules/mesh-delivery-builder/module.json
@@ -165,6 +165,14 @@
       "place": ".",
       "unknown": "program"
     },
+    {
+      "id": "toolchain-wait",
+      "type": "file",
+      "path": "${dir:state}/toolchain-wait-minutes",
+      "owner": "mesh-delivery-builder",
+      "mode": "0600",
+      "content": "${config:toolchain-wait-minutes}"
+    },
     {
       "id": "builder",
       "type": "process",
@@ -175,7 +183,7 @@
       ],
       "env": {
         "MESH_BROKER_FILE": "${dir:state}/broker",
-        "MESH_BUILDER_TOOLCHAIN_WAIT_MINUTES": "${config:toolchain-wait-minutes}"
+        "MESH_BUILDER_TOOLCHAIN_WAIT_FILE": "${dir:state}/toolchain-wait-minutes"
       },
       "user": "mesh-delivery-builder",
       "health": {