feat(FN-2999): harden research lifecycle with idempotent cancel/retry, SSE

Merges FN-2999 research hardening (idempotent cancel/retry routes, aligned SSE event wiring, and cleaned status handling in the core research store and orchestrator) plus UI improvements to AgentDetailView header actions and planning disclosure UX in the modal, with a CSS token fallback fix in Scrip

Fusion-Task-Id: FN-2999

packages/core/src/__tests__/research-store.test.ts

@@ -24,7 +24,7 @@ describe("ResearchStore", () => {
     const updated = store.updateRun(run.id, { topic: "new topic", error: "oops" });
     expect(updated?.topic).toBe("new topic");
 
-    const listed = store.listRuns({ status: "pending" });
+    const listed = store.listRuns({ status: "queued" });
     expect(listed.map((r) => r.id)).toContain(run.id);
 
     expect(store.deleteRun(run.id)).toBe(true);
@@ -58,8 +58,8 @@ describe("ResearchStore", () => {
 
     expect(() => store.updateRun(run.id, { topic: "changed" })).toThrow(ResearchLifecycleError);
 
-    const pending = store.createRun({ query: "pending" });
-    expect(() => store.updateStatus(pending.id, "completed")).toThrow(/Invalid run status transition/i);
+    const queued = store.createRun({ query: "queued" });
+    expect(() => store.updateStatus(queued.id, "completed")).toThrow(/Invalid run status transition/i);
   });
 
   it("persists lifecycle events to research_run_events", () => {
@@ -131,6 +131,32 @@ describe("ResearchStore", () => {
     expect(store.getExports(r1.id)).toHaveLength(0);
   });
 
+  it("supports idempotent cancellation request transition", () => {
+    const run = store.createRun({ query: "cancel me" });
+    const first = store.requestCancellation(run.id);
+    expect(first.status).toBe("cancelling");
+    const second = store.requestCancellation(run.id);
+    expect(second.status).toBe("cancelling");
+
+    store.updateStatus(run.id, "cancelled");
+    const terminal = store.requestCancellation(run.id);
+    expect(terminal.status).toBe("cancelled");
+  });
+
+  it("marks retry exhaustion when max attempts reached", () => {
+    const run = store.createRun({ query: "retry", lifecycle: { attempt: 3, maxAttempts: 3 } });
+    store.updateStatus(run.id, "failed", {
+      lifecycle: {
+        ...(run.lifecycle ?? {}),
+        retryable: true,
+        failureClass: "retryable_transient",
+      },
+    });
+
+    expect(() => store.createRetryRun(run.id)).toThrow(/non-retryable|exhausted retries/i);
+    expect(store.getRun(run.id)?.status).toBe("retry_exhausted");
+  });
+
   it("emits status events and throws for missing run mutations", () => {
     const onStatus = vi.fn();
     const onCompleted = vi.fn();