diff --git a/main.go b/main.go
index 57447d1..37ef7da 100644
--- a/main.go
+++ b/main.go
@@ -6,9 +6,12 @@ import (
 	"encoding/json"
 	"flag"
 	"fmt"
+	"io"
 	"io/fs"
 	"io/ioutil"
 	"log"
+	"net/http"
+	"net/url"
 	"os"
 	"os/signal"
 	"path"
@@ -21,13 +24,15 @@ import (
 )
 
 var (
-	Debug         = os.Getenv("DEBUG") == "true"
-	ConstTitle    = os.Getenv("YAML_C_TITLE")
-	ConstSeason   = os.Getenv("YAML_C_SEASON")
-	ConstEpisode  = os.Getenv("YAML_C_EPISODE")
-	ConstOutd     = os.Getenv("YAML_O")
-	Dry           = os.Getenv("YAML_D") == "true" || os.Getenv("DRY") == "true"
-	ConstPatterns = os.Getenv("YAML_P")
+	Debug                        = os.Getenv("DEBUG") == "true"
+	ConstTitle                   = os.Getenv("YAML_C_TITLE")
+	ConstSeason                  = os.Getenv("YAML_C_SEASON")
+	ConstEpisode                 = os.Getenv("YAML_C_EPISODE")
+	ConstOutd                    = os.Getenv("YAML_O")
+	Dry                          = os.Getenv("YAML_D") == "true" || os.Getenv("DRY") == "true"
+	ConstPatterns                = os.Getenv("YAML_P")
+	WebhookOnRecursiveMiss       = os.Getenv("RECURSIVE_MISSING_WEBHOOK")
+	WebhookOnRecursiveMissCacheD = os.Getenv("RECURSIVE_MISSING_WEBHOOK_CACHE_D")
 )
 
 type Yaml struct {
@@ -81,6 +86,32 @@ func Recursive(ctx context.Context) error {
 
 		p := path.Join(d, YamlFile)
 		if _, err := os.Stat(p); err != nil {
+			log.Printf("%s has no %s", d, YamlFile)
+			if WebhookOnRecursiveMiss != "" && WebhookOnRecursiveMissCacheD != "" {
+				cacheP := regexp.MustCompile(`[^a-zA-Z0-9]`).ReplaceAllString(p, `_`)
+				cacheP = path.Join(WebhookOnRecursiveMissCacheD, cacheP)
+				if _, err := os.Stat(cacheP); err != nil {
+					u, err := url.Parse(WebhookOnRecursiveMiss)
+					if err != nil {
+						return fmt.Errorf("WebhookOnRecursiveMiss (%s) invalid: %w", WebhookOnRecursiveMiss, err)
+					}
+					q := u.Query()
+					q.Set("p", p)
+					u.RawQuery = q.Encode()
+					resp, err := http.Post(u.String(), "text/plain", strings.NewReader(p))
+					if err != nil {
+						return fmt.Errorf("failed to call %s for missing %s: %w", WebhookOnRecursiveMiss, p, err)
+					}
+					defer resp.Body.Close()
+					defer io.Copy(io.Discard, resp.Body)
+					if resp.StatusCode > 250 {
+						return fmt.Errorf("unexpected status code from %s for %s: %w", WebhookOnRecursiveMiss, p, err)
+					}
+
+					os.MkdirAll(path.Dir(cacheP), os.ModePerm)
+					ioutil.WriteFile(cacheP, []byte{}, os.ModePerm)
+				}
+			}
 		} else if err := func() error {
 			y, err := NewYaml(path.Join(d, YamlFile))
 			if err != nil {
diff --git a/main_test.go b/main_test.go
index d3d94cc..5322abe 100644
--- a/main_test.go
+++ b/main_test.go
@@ -3,6 +3,8 @@ package main_test
 import (
 	"context"
 	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
 	"os"
 	"path"
 	"slices"
@@ -149,6 +151,38 @@ func TestRunWith(t *testing.T) {
 }
 
 func TestRecursive(t *testing.T) {
+	webhooks := []string{}
+	s := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Query().Get("p") == "" {
+			t.Errorf("webhook wasn't called with ?p: %s", r.URL.String())
+		}
+		b, _ := ioutil.ReadAll(r.Body)
+		if string(b) != r.URL.Query().Get("p") {
+			t.Errorf("webhook wasn't called with ?p == {body}: %q vs %q", r.URL.Query().Get("p"), b)
+		}
+		webhooks = append(webhooks, string(b))
+	}))
+	t.Cleanup(s.Close)
+	t.Cleanup(func() {
+		t.Logf("webhooks: %+v", webhooks)
+		if len(webhooks) == 0 {
+			t.Errorf("expected webhook calls but got none")
+		}
+		deduped := slices.Clone(webhooks)
+		slices.Sort(deduped)
+		slices.Compact(deduped)
+		if len(deduped) != len(webhooks) {
+			t.Errorf("expected no duplicate webhooks but got %+v", webhooks)
+		}
+	})
+
+	main.WebhookOnRecursiveMiss = s.URL
+	main.WebhookOnRecursiveMissCacheD = t.TempDir()
+	t.Cleanup(func() {
+		main.WebhookOnRecursiveMiss = ""
+		main.WebhookOnRecursiveMissCacheD = ""
+	})
+
 	was, _ := os.Getwd()
 	t.Cleanup(func() { os.Chdir(was) })
 	os.Chdir(t.TempDir())
@@ -196,6 +230,8 @@ func TestRecursive(t *testing.T) {
 
 	if err := main.Recursive(context.Background()); err != nil {
 		t.Fatal(err)
+	} else if err := main.Recursive(context.Background()); err != nil {
+		t.Fatalf("failed second run: %v", err)
 	}
 
 	exists(t, path.Join(outd, "A", "A_SAEA.a"))