diff --git a/src/ui/public/app.js b/src/ui/public/app.js
index 57abb4a..689eefb 100644
--- a/src/ui/public/app.js
+++ b/src/ui/public/app.js
@@ -117,6 +117,9 @@ const MANIFEST_EVENT_TRIGGERS = [
   "branch_merged",
 ];
 
+const RUN_MANIFEST_EDITOR_VALUE = "__editor__";
+const RUN_MANIFEST_EDITOR_LABEL = "[Use Manifest Editor JSON]";
+
 function fmtMoney(value) {
   return `$${Number(value || 0).toFixed(4)}`;
 }
@@ -838,6 +841,26 @@ function parseJsonSafe(text, fallback) {
   }
 }
 
+function dedupeNonEmptyStrings(values) {
+  const output = [];
+  const seen = new Set();
+
+  for (const value of values) {
+    if (typeof value !== "string") {
+      continue;
+    }
+
+    const normalized = value.trim();
+    if (!normalized || seen.has(normalized)) {
+      continue;
+    }
+    seen.add(normalized);
+    output.push(normalized);
+  }
+
+  return output;
+}
+
 function populateSelect(select, values, selectedValue) {
   const previous = selectedValue || select.value;
   select.innerHTML = "";
@@ -857,6 +880,35 @@ function populateSelect(select, values, selectedValue) {
   }
 }
 
+function populateRunManifestSelect(values, selectedValue) {
+  const previous = selectedValue || dom.runManifestSelect.value;
+  dom.runManifestSelect.innerHTML = "";
+
+  const editorOption = document.createElement("option");
+  editorOption.value = RUN_MANIFEST_EDITOR_VALUE;
+  editorOption.textContent = RUN_MANIFEST_EDITOR_LABEL;
+  dom.runManifestSelect.append(editorOption);
+
+  for (const value of values) {
+    const option = document.createElement("option");
+    option.value = value;
+    option.textContent = value;
+    dom.runManifestSelect.append(option);
+  }
+
+  if (previous && [...dom.runManifestSelect.options].some((option) => option.value === previous)) {
+    dom.runManifestSelect.value = previous;
+    return;
+  }
+
+  if (state.selectedManifestPath && values.includes(state.selectedManifestPath)) {
+    dom.runManifestSelect.value = state.selectedManifestPath;
+    return;
+  }
+
+  dom.runManifestSelect.value = RUN_MANIFEST_EDITOR_VALUE;
+}
+
 async function loadConfig() {
   const payload = await apiRequest("/api/config");
   state.config = payload.config;
@@ -888,14 +940,19 @@ async function loadConfig() {
 
 async function loadManifests() {
   const payload = await apiRequest("/api/manifests");
-  state.manifests = payload.manifests;
+  const manifests = dedupeNonEmptyStrings([
+    ...(Array.isArray(payload.manifests) ? payload.manifests : []),
+    state.selectedManifestPath,
+    dom.manifestPath.value,
+  ]);
+  state.manifests = manifests;
 
   if (!state.selectedManifestPath && state.manifests.length > 0) {
     state.selectedManifestPath = state.manifests[0];
   }
 
   populateSelect(dom.graphManifestSelect, state.manifests, state.selectedManifestPath);
-  populateSelect(dom.runManifestSelect, state.manifests, state.selectedManifestPath);
+  populateRunManifestSelect(state.manifests, state.selectedManifestPath);
 
   if (state.selectedManifestPath) {
     dom.manifestPath.value = state.selectedManifestPath;
@@ -1332,9 +1389,10 @@ async function startRun(event) {
     return;
   }
 
+  const manifestSelection = dom.runManifestSelect.value.trim();
+
   const payload = {
     prompt,
-    manifestPath: dom.runManifestSelect.value,
     executionMode: dom.runExecutionMode.value,
     provider: dom.runProvider.value,
     topologyHint: dom.runTopologyHint.value.trim() || undefined,
@@ -1342,6 +1400,20 @@ async function startRun(event) {
     simulateValidationNodeIds: fromCsv(dom.runValidationNodes.value),
   };
 
+  if (manifestSelection === RUN_MANIFEST_EDITOR_VALUE) {
+    const manifestFromEditor = parseJsonSafe(dom.manifestEditor.value, null);
+    if (!manifestFromEditor) {
+      showRunStatus("Manifest editor JSON is invalid. Save or fix it before running.", true);
+      return;
+    }
+    payload.manifest = manifestFromEditor;
+  } else if (manifestSelection) {
+    payload.manifestPath = manifestSelection;
+  } else {
+    showRunStatus("Select a manifest path or choose editor JSON.", true);
+    return;
+  }
+
   try {
     const response = await apiRequest("/api/runs", {
       method: "POST",
@@ -1458,7 +1530,7 @@ async function loadManifestEditor() {
     dom.manifestPath.value = payload.manifest.path;
     state.selectedManifestPath = payload.manifest.path;
     populateSelect(dom.graphManifestSelect, state.manifests, state.selectedManifestPath);
-    populateSelect(dom.runManifestSelect, state.manifests, state.selectedManifestPath);
+    populateRunManifestSelect(state.manifests, state.selectedManifestPath);
     setManifestStatus(`Loaded ${payload.manifest.path}.`);
   } catch (error) {
     setManifestStatus(error instanceof Error ? error.message : String(error), true);
@@ -1511,7 +1583,9 @@ async function saveManifest(event) {
     renderManifestHelper();
     await loadManifests();
     dom.graphManifestSelect.value = state.selectedManifestPath;
-    dom.runManifestSelect.value = state.selectedManifestPath;
+    if ([...dom.runManifestSelect.options].some((option) => option.value === state.selectedManifestPath)) {
+      dom.runManifestSelect.value = state.selectedManifestPath;
+    }
     setManifestStatus(`Saved ${payload.manifest.path}.`);
     await refreshGraph();
   } catch (error) {
@@ -1528,7 +1602,9 @@ function bindUiEvents() {
 
   dom.graphManifestSelect.addEventListener("change", async () => {
     state.selectedManifestPath = dom.graphManifestSelect.value;
-    dom.runManifestSelect.value = state.selectedManifestPath;
+    if ([...dom.runManifestSelect.options].some((option) => option.value === state.selectedManifestPath)) {
+      dom.runManifestSelect.value = state.selectedManifestPath;
+    }
     dom.manifestPath.value = state.selectedManifestPath;
     await refreshGraph();
   });