fix: eliminate all 4xx noise from scene walks

- buildScenarios: drop the /api/runtime/transactions/{id} headline GET
  entirely. Synthesize the RuntimeTransaction shape from the work-item
  data. Backend's per-id endpoint is broken (500 on valid IDs, 404 on
  work-item IDs); we already have all the display fields we need.
- store.ts pollLiveTick: don't refetch headline transaction; reuse
  the existing scenario.raw.headlineRt synthesized at build time.
- useBackendHealth: pass the bearer token if present so the probe
  returns 200 instead of 401 for authenticated users. The probe still
  treats 401 as 'up' for unauthenticated landing page.
- agentMemory.remember: track ensureVault result. Skip the edge attach
  apply-batch entirely if the vault didn't materialize, so we don't
  fire a guaranteed-422 create_edge against a missing from-doc.

src/lib/agentMemory.ts

@@ -66,7 +66,7 @@ export const agentMemory = {
   async remember(email: string, content: string, tags: string[] = [], signal?: AbortSignal): Promise<string | null> {
     if (!content.trim()) return null;
     const vaultKey = vaultKeyFor(email);
-    await ensureVault(vaultKey, email, signal);
+    const vaultReady = await ensureVault(vaultKey, email, signal);
     const doc = await fetch(`${api.config.baseUrl}/api/ea2/flow`, {
       method: "POST",
       headers: authHeaders(),
@@ -83,6 +83,10 @@ export const agentMemory = {
     });
     if (!doc.ok) return null;
     const mem = await doc.json();
+    if (!vaultReady) {
+      console.warn(`[memory] vault not ready for ${email}, skipping edge attach`);
+      return mem._key;
+    }
     try {
       const edgeRes = await fetch(`${api.config.baseUrl}/api/ea2/apply-batch`, {
         method: "POST",

src/lib/buildScenarios.ts

@@ -272,9 +272,7 @@ export async function buildLiveScenariosFromApi(signal?: AbortSignal): Promise<{
       const recentCandidates = c.cases
         .filter((w) => w.transaction_id && w.transaction_id !== headlineCase?.transaction_id)
         .slice(0, 3);
-      const headlineRt = headlineCase?.transaction_id
-        ? (await api.transaction(headlineCase.transaction_id, signal)) ?? workItemToRt(headlineCase)
-        : null;
+      const headlineRt = workItemToRt(headlineCase);
       const recent: RuntimeTransaction[] = recentCandidates
         .map((w) => workItemToRt(w))
         .filter((r): r is RuntimeTransaction => r != null);

src/lib/useBackendHealth.ts

@@ -12,7 +12,10 @@ const POLL_MS = 30_000;
 
 async function probeOnce(signal: AbortSignal): Promise<BackendHealth> {
   try {
-    const r = await fetch("/api/v1/auth/me", { method: "GET", signal });
+    const token = typeof sessionStorage !== "undefined" ? sessionStorage.getItem("fm.mc.token.v1") || "" : "";
+    const headers: Record<string, string> = { "Accept": "application/json" };
+    if (token) headers.Authorization = `Bearer ${token}`;
+    const r = await fetch("/api/v1/auth/me", { method: "GET", headers, signal });
     if (r.status === 200 || r.status === 401 || r.status === 403) return "up";
     if (r.status === 502 || r.status === 504) return "proxy-down";
     if (r.status === 503) return "auth-down";

src/state/store.ts

@@ -311,13 +311,8 @@ export const useApp = create<AppState>((set, get) => {
       try {
         const workItems = await api.workItems();
         const sc = s.scenarios.find((x) => x.id === s.scenarioId);
-        let headlineRt = null;
-        if (sc?.headlineTx) {
-          // Best-effort: the per-transaction endpoint can 500/404 when the
-          // runtime DB is unreachable. Don't surface that as a polling error —
-          // existing headlineRt in scenario.raw is still valid for display.
-          headlineRt = await api.transaction(sc.headlineTx).catch(() => null);
-        }
+        const existingHeadline = (sc?.raw as { headlineRt?: unknown } | undefined)?.headlineRt ?? null;
+        const headlineRt = existingHeadline;
         const updatedScenarios = s.scenarios.map((scen) => {
           if (!scen.live) return scen;
           const myCases = workItems.filter((w) => w.definition_key === scen.defKey);