diff --git a/internal/api/handlers.go b/internal/api/handlers.go
index e9af556..420ff35 100644
--- a/internal/api/handlers.go
+++ b/internal/api/handlers.go
@@ -56,7 +56,12 @@ func (h *Handlers) Update(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	jobs, err := h.finder.FindJobs(r.Context(), req.Image)
+	requestedImage := req.Image
+	if req.Tag != "" {
+		requestedImage = req.Image + ":" + req.Tag
+	}
+
+	jobs, err := h.finder.FindJobs(r.Context(), requestedImage)
 	if err != nil {
 		writeJSONError(w, http.StatusInternalServerError, "discovery failed: "+err.Error())
 		return
diff --git a/internal/api/handlers_test.go b/internal/api/handlers_test.go
index b62f830..462540a 100644
--- a/internal/api/handlers_test.go
+++ b/internal/api/handlers_test.go
@@ -21,9 +21,21 @@ import (
 type fakeFinder struct {
 	jobs []discovery.Job
 	err  error
+
+	// gotImage records the image argument passed to FindJobs, for
+	// assertions on the exact reference the handler built.
+	gotImage string
+	// swarmShaped, when true, makes FindJobs return a Job whose Image
+	// field carries the received image argument, simulating
+	// discovery.SwarmDiscovery.FindJobs.
+	swarmShaped bool
 }
 
-func (f *fakeFinder) FindJobs(_ context.Context, _ string) ([]discovery.Job, error) {
+func (f *fakeFinder) FindJobs(_ context.Context, image string) ([]discovery.Job, error) {
+	f.gotImage = image
+	if f.swarmShaped {
+		return []discovery.Job{{Service: "myapp_web", ServiceID: "svc1", Image: image}}, f.err
+	}
 	return f.jobs, f.err
 }
 
@@ -157,6 +169,42 @@ func TestHealthz_503WhenDockerDown(t *testing.T) {
 	require.Equal(t, http.StatusServiceUnavailable, w.Code)
 }
 
+func TestUpdate_FindJobsCalledWithTaggedImage(t *testing.T) {
+	finder := &fakeFinder{}
+	h := api.NewHandlers(finder, &fakeSubmitter{}, &fakePinger{}, "v0.0.0", "abc", "now", nil)
+	body, _ := json.Marshal(api.UpdateRequest{Image: "registry.example.com/myapp", Tag: "v2"})
+	req := httptest.NewRequest(http.MethodPost, "/update", bytes.NewReader(body))
+	w := httptest.NewRecorder()
+	h.Update(w, req)
+	require.Equal(t, "registry.example.com/myapp:v2", finder.gotImage)
+}
+
+func TestUpdate_FindJobsCalledWithBareImageWhenNoTag(t *testing.T) {
+	finder := &fakeFinder{}
+	h := api.NewHandlers(finder, &fakeSubmitter{}, &fakePinger{}, "v0.0.0", "abc", "now", nil)
+	body, _ := json.Marshal(api.UpdateRequest{Image: "registry.example.com/myapp"})
+	req := httptest.NewRequest(http.MethodPost, "/update", bytes.NewReader(body))
+	w := httptest.NewRecorder()
+	h.Update(w, req)
+	require.Equal(t, "registry.example.com/myapp", finder.gotImage)
+}
+
+func TestUpdate_SwarmModeThreadsTagThroughDiscovery(t *testing.T) {
+	finder := &fakeFinder{swarmShaped: true}
+	h := api.NewHandlers(finder, &fakeSubmitter{}, &fakePinger{}, "v0.0.0", "abc", "now", nil)
+	body, _ := json.Marshal(api.UpdateRequest{Image: "registry.example.com/myapp", Tag: "v2"})
+	req := httptest.NewRequest(http.MethodPost, "/update", bytes.NewReader(body))
+	w := httptest.NewRecorder()
+	h.Update(w, req)
+	require.Equal(t, http.StatusOK, w.Code)
+	// The fake Finder's returned Job.Image (as SwarmDiscovery would build
+	// it) reflects the image argument it received from the handler.
+	// Asserting on the captured argument proves the full request ->
+	// discovery flow carries the tag through to what would reach the
+	// SwarmExecutor.
+	require.Equal(t, "registry.example.com/myapp:v2", finder.gotImage)
+}
+
 func TestVersion(t *testing.T) {
 	h := api.NewHandlers(&fakeFinder{}, &fakeSubmitter{}, &fakePinger{}, "v1.2.3", "abcdef", "2026-05-22T00:00:00Z", nil)
 	req := httptest.NewRequest(http.MethodGet, "/version", nil)