diff --git a/internal/gateway/api.go b/internal/gateway/api.go
index 5610666..dfa1f4a 100644
--- a/internal/gateway/api.go
+++ b/internal/gateway/api.go
@@ -32,7 +32,11 @@ func (g *Gateway) handleAdaptersAPI(w http.ResponseWriter, r *http.Request) {
 			writeJSON(w, http.StatusOK, map[string]interface{}{"adapters": g.core.ListAdapters()})
 			return
 		}
-		writeError(w, http.StatusNotFound, "not_found", "adapter code not exposed; edit in UI")
+		// A GET on a specific adapter is almost always a client that meant to
+		// DELETE it but let fetch default to GET; say so instead of only
+		// reporting that the code is not exposed.
+		writeError(w, http.StatusNotFound, "not_found",
+			"adapter code not exposed; edit in UI (to remove it use DELETE /api/adapters/"+path+")")
 	case http.MethodPost:
 		var p adapterPayload
 		if err := json.NewDecoder(r.Body).Decode(&p); err != nil {
diff --git a/internal/gateway/gateway_test.go b/internal/gateway/gateway_test.go
index 847a94a..2e2e636 100644
--- a/internal/gateway/gateway_test.go
+++ b/internal/gateway/gateway_test.go
@@ -914,3 +914,88 @@ func TestStatsRecordsAPIScopedToOwnKey(t *testing.T) {
 		}
 	}
 }
+
+// TestKeyDeleteRoundTrip is the end-to-end version of the bug users hit:
+// deleting a gateway key from the admin UI. It also asserts the GET-on-a-key
+// error names the right verb, since that message is what a mis-methoded client
+// actually sees.
+func TestKeyDeleteRoundTrip(t *testing.T) {
+	g := newTestGateway(t)
+
+	rr := doReq(t, g, http.MethodPost, "/api/keys", `{"name":"doomed","role":"user"}`)
+	if rr.Code != 200 {
+		t.Fatalf("create: %d %s", rr.Code, rr.Body.String())
+	}
+	var created struct {
+		Key struct {
+			Key  string `json:"key"`
+			Name string `json:"name"`
+		} `json:"key"`
+	}
+	if err := json.Unmarshal(rr.Body.Bytes(), &created); err != nil {
+		t.Fatalf("decode create: %v", err)
+	}
+	if created.Key.Key == "" {
+		t.Fatalf("no key returned: %s", rr.Body.String())
+	}
+
+	// DELETE removes it
+	rr = doReq(t, g, http.MethodDelete, "/api/keys/"+url.PathEscape(created.Key.Key), "")
+	if rr.Code != 200 {
+		t.Fatalf("delete: %d %s", rr.Code, rr.Body.String())
+	}
+	for _, k := range g.core.ListKeys() {
+		if k.Key == created.Key.Key {
+			t.Fatal("key still present after DELETE")
+		}
+	}
+
+	// deleting again is a clean 404, not a 500
+	rr = doReq(t, g, http.MethodDelete, "/api/keys/"+url.PathEscape(created.Key.Key), "")
+	if rr.Code != http.StatusNotFound {
+		t.Fatalf("second delete: %d, want 404", rr.Code)
+	}
+}
+
+// TestKeyGetOnSpecificKeyNamesTheVerb: a GET on /api/keys/{key} is what a
+// client that forgot to set method:"DELETE" ends up sending. The error must say
+// which verb to use instead of just "use GET /api/keys", which reads as if the
+// caller did nothing wrong.
+func TestKeyGetOnSpecificKeyNamesTheVerb(t *testing.T) {
+	g := newTestGateway(t)
+	rr := doReq(t, g, http.MethodGet, "/api/keys/sk-whatever", "")
+	if rr.Code != http.StatusNotFound {
+		t.Fatalf("status = %d, want 404", rr.Code)
+	}
+	body := rr.Body.String()
+	for _, want := range []string{"DELETE /api/keys/", "PUT /api/keys/"} {
+		if !strings.Contains(body, want) {
+			t.Errorf("error message should mention %q, got: %s", want, body)
+		}
+	}
+}
+
+// TestAdapterGetOnSpecificAdapterNamesDelete is the same guard for the adapters
+// endpoint, whose delAdapter helper had the identical missing-method bug.
+func TestAdapterGetOnSpecificAdapterNamesDelete(t *testing.T) {
+	g := newTestGateway(t)
+	rr := doReq(t, g, http.MethodGet, "/api/adapters/openai", "")
+	if rr.Code != http.StatusNotFound {
+		t.Fatalf("status = %d, want 404", rr.Code)
+	}
+	if !strings.Contains(rr.Body.String(), "DELETE /api/adapters/openai") {
+		t.Errorf("error should name the DELETE verb, got: %s", rr.Body.String())
+	}
+}
+
+// TestCannotDeleteOwnKey keeps the admin from locking themselves out.
+func TestCannotDeleteOwnKey(t *testing.T) {
+	g := newTestGateway(t)
+	rr := doReq(t, g, http.MethodDelete, "/api/keys/sk-test", "")
+	if rr.Code != http.StatusBadRequest {
+		t.Fatalf("status = %d, want 400", rr.Code)
+	}
+	if !strings.Contains(rr.Body.String(), "logged in with") {
+		t.Errorf("unexpected message: %s", rr.Body.String())
+	}
+}
diff --git a/internal/gateway/keys.go b/internal/gateway/keys.go
index 70445c7..d95d58e 100644
--- a/internal/gateway/keys.go
+++ b/internal/gateway/keys.go
@@ -29,7 +29,11 @@ func (g *Gateway) handleKeysAPI(w http.ResponseWriter, r *http.Request) {
 	switch r.Method {
 	case http.MethodGet:
 		if path != "" {
-			writeError(w, http.StatusNotFound, "not_found", "use GET /api/keys")
+			// A GET on a specific key is almost always a client that meant to
+			// DELETE or PUT it but let fetch default to GET. Name the verbs
+			// instead of only pointing back at the collection endpoint.
+			writeError(w, http.StatusNotFound, "not_found",
+				"no such endpoint; use GET /api/keys to list, DELETE /api/keys/{key} to remove, PUT /api/keys/{key} to update")
 			return
 		}
 		writeJSON(w, http.StatusOK, map[string]interface{}{"keys": g.core.ListKeys()})
diff --git a/internal/gateway/ui/index.html b/internal/gateway/ui/index.html
index 970b5e5..344e33d 100644
--- a/internal/gateway/ui/index.html
+++ b/internal/gateway/ui/index.html
@@ -3027,9 +3027,9 @@
       }
       async function delSource(name) {
         if (!confirm(tFmt("confirmDelSrc", name))) return;
-          await api("/api/sources/" + encodeURIComponent(name), {
-            method: "DELETE",
-          });
+        await api("/api/sources/" + encodeURIComponent(name), {
+          method: "DELETE",
+        });
         toast(t("toastDelOk"));
         renderSources();
       }
@@ -3992,6 +3992,7 @@
       async function delAdapter(name) {
         if (!confirm(tFmt("confirmDelAdp", name))) return;
         await api("/api/adapters/" + encodeURIComponent(name), {
+          method: "DELETE",
         });
         toast(t("toastDelOk"));
         renderAdapters();
@@ -4545,6 +4546,7 @@
         if (!confirm(tFmt("kDelConfirm", name || key))) return;
         try {
           await api("/api/keys/" + encodeURIComponent(key), {
+            method: "DELETE",
           });
           toast(t("toastDelOk"));
           loadKeys();
diff --git a/internal/gateway/ui_contract_test.go b/internal/gateway/ui_contract_test.go
new file mode 100644
index 0000000..f3197ca
--- /dev/null
+++ b/internal/gateway/ui_contract_test.go
@@ -0,0 +1,178 @@
+package gateway
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+	"testing"
+)
+
+// The WebUI talks to this package through a tiny `api(path, options)` helper
+// that wraps fetch(). fetch() defaults to GET when no method is given, so an
+// options object without `method` silently turns a DELETE/PUT into a GET —
+// the request hits the wrong branch of the handler and the user sees a
+// confusing error like "use GET /api/keys" while nothing is deleted.
+//
+// This has now bitten twice: ab20f1b fixed delSource/delTemplate, and the very
+// same pattern was still live in delKey (deleting a gateway key was impossible)
+// and delAdapter. Reviewing 4000+ lines of inline JS by eye clearly does not
+// catch it, so it is pinned here instead.
+
+// apiCallRe finds the start of every api(...) call in the UI source.
+var apiCallRe = regexp.MustCompile(`\bapi\(`)
+
+// uiSource returns the embedded WebUI document.
+func uiSource(t *testing.T) string {
+	t.Helper()
+	b, err := uiFS.ReadFile("ui/index.html")
+	if err != nil {
+		t.Fatalf("read embedded ui: %v", err)
+	}
+	return string(b)
+}
+
+// extractCall returns the source of the balanced api(...) call starting at the
+// opening parenthesis index, plus the line number it starts on.
+func extractCall(src string, openIdx int) (string, bool) {
+	depth := 0
+	for i := openIdx; i < len(src); i++ {
+		switch src[i] {
+		case '(':
+			depth++
+		case ')':
+			depth--
+			if depth == 0 {
+				return src[openIdx : i+1], true
+			}
+		case '\n':
+			// A call spanning more than ~25 lines is not one of ours; bail out
+			// rather than scanning the rest of the document.
+			if i-openIdx > 4000 {
+				return "", false
+			}
+		}
+	}
+	return "", false
+}
+
+func lineOf(src string, idx int) int {
+	return strings.Count(src[:idx], "\n") + 1
+}
+
+// TestUIAPICallsDeclareMethod asserts that every api() call passing an options
+// object also declares an HTTP method (or is a GET that only passes an
+// AbortSignal). Without this, fetch defaults to GET and mutating endpoints are
+// never reached.
+func TestUIAPICallsDeclareMethod(t *testing.T) {
+	src := uiSource(t)
+	var offenders []string
+	for _, m := range apiCallRe.FindAllStringIndex(src, -1) {
+		open := m[1] - 1 // index of '('
+		call, ok := extractCall(src, open)
+		if !ok {
+			continue
+		}
+		// No options object at all => a plain GET, which is fine.
+		if !strings.Contains(call, "{") {
+			continue
+		}
+		if strings.Contains(call, "method:") {
+			continue
+		}
+		// A read that only carries an AbortSignal is a deliberate GET.
+		if strings.Contains(call, "signal:") && !strings.Contains(call, "body:") {
+			continue
+		}
+		offenders = append(offenders, fmt.Sprintf("line %d: %s", lineOf(src, open), oneLine(call)))
+	}
+	if len(offenders) > 0 {
+		t.Fatalf("api() called with an options object but no method (fetch will send GET):\n  %s",
+			strings.Join(offenders, "\n  "))
+	}
+}
+
+// TestUIDeleteHelpersUseDelete pins the specific helpers that remove things.
+// Each must issue a DELETE; a GET here is the exact bug users reported as
+// "cannot delete key: use GET /api/keys".
+func TestUIDeleteHelpersUseDelete(t *testing.T) {
+	src := uiSource(t)
+	for _, fn := range []string{"delKey", "delAdapter", "delSource", "delTemplate"} {
+		body, ok := jsFunctionBody(src, fn)
+		if !ok {
+			t.Errorf("helper %s() not found in the WebUI", fn)
+			continue
+		}
+		if !strings.Contains(body, "api(") {
+			t.Errorf("%s() does not call api()", fn)
+			continue
+		}
+		if !strings.Contains(body, `method: "DELETE"`) {
+			t.Errorf("%s() must issue a DELETE, got:\n%s", fn, body)
+		}
+	}
+}
+
+// TestUIMutatingHelpersUseWriteMethods covers the write (non-delete) helpers:
+// each must declare an explicit POST/PUT/PATCH.
+func TestUIMutatingHelpersUseWriteMethods(t *testing.T) {
+	src := uiSource(t)
+	want := map[string][]string{
+		"createKey":     {`method: "POST"`},
+		"putScope":      {`method: "PUT"`},
+		"uploadAdapter": {`method: "POST"`},
+		"saveAuto":      {`method: "PUT"`, `method: "POST"`},
+	}
+	for fn, methods := range want {
+		body, ok := jsFunctionBody(src, fn)
+		if !ok {
+			continue // helper renamed or absent: the method test above still guards it
+		}
+		found := false
+		for _, m := range methods {
+			if strings.Contains(body, m) {
+				found = true
+				break
+			}
+		}
+		if !found {
+			t.Errorf("%s() must declare one of %v", fn, methods)
+		}
+	}
+}
+
+// jsFunctionBody returns the source of `function name(` / `async function name(`
+// up to its closing brace, using brace balancing.
+func jsFunctionBody(src, name string) (string, bool) {
+	for _, prefix := range []string{"async function " + name + "(", "function " + name + "("} {
+		idx := strings.Index(src, prefix)
+		if idx < 0 {
+			continue
+		}
+		open := strings.Index(src[idx:], "{")
+		if open < 0 {
+			continue
+		}
+		open += idx
+		depth := 0
+		for i := open; i < len(src); i++ {
+			switch src[i] {
+			case '{':
+				depth++
+			case '}':
+				depth--
+				if depth == 0 {
+					return src[idx : i+1], true
+				}
+			}
+		}
+	}
+	return "", false
+}
+
+func oneLine(s string) string {
+	s = strings.Join(strings.Fields(s), " ")
+	if len(s) > 140 {
+		return s[:140] + "…"
+	}
+	return s
+}