feat(confidence-engine): place zero-Open-Questions milestone at Open Questions position

Move the milestone invitation from after Clarified Questions to occupy
the same spatial position as Open Questions — between Current Understanding
and Questions we have clarified. Uses ternary: openUnknowns > 0 ? OpenQuestionsUI : milestoneAllowed ? MilestoneInvitation : null, followed by ClarifiedQuestionsUI unconditionally. No duplication of clarified cards or Re-open controls.

tests/open-questions-vs-assumptions.test.jsx

@@ -2739,4 +2739,140 @@ describe("v0.49 workspace controls", () => {
       expect(doneForNowIds).toHaveLength(0);
     });
   });
+});
+
+// ── Zero Open Questions: end-of-investigation review invitation (v0.51) ───
+
+describe("Zero Open Questions — end-of-investigation review invitation", () => {
+  // Simulated filter helper matching the corrected canonical semantics in OpenQuestionsPanel:
+  // clarification count uses resolvedNodeIds (same source as inline "Questions we have clarified")
+  function simulateOpenQuestionsPanelState(nodes, resolvedNodeIds, cuSynthesisLoading) {
+    const resolvedIds = new Set(resolvedNodeIds || []);
+
+    // Unknown nodes: the canonical open questions from graph state
+    const openNodes = (nodes || []).filter(
+      (n) => n.kind === "unknown" && !resolvedIds.has(n.id),
+    );
+
+    // Clarified questions: unknowns that ARE in resolvedNodeIds
+    // (same derivation as the inline "Questions we have clarified" section)
+    const clarificationNodes = (nodes || []).filter(
+      (n) => n.kind === "unknown" && resolvedIds.has(n.id),
+    );
+
+    const showInvitation =
+      openNodes.length === 0 &&
+      clarificationNodes.length > 0 &&
+      !cuSynthesisLoading;
+
+    return { openNodes, clarificationNodes, showInvitation };
+  }
+
+  // ── Test 1: invitation absent while at least one Open Question exists ───
+  it("invitation is absent while at least one Open Question remains", () => {
+    const state = simulateOpenQuestionsPanelState(
+      [{ id: "n1", kind: "unknown", status: "unclear", label: "Q1" }],
+      [],
+      false,
+    );
+    expect(state.showInvitation).toBe(false);
+    expect(state.openNodes).toHaveLength(1);
+  });
+
+  // ── Test 2: invitation present when Open Questions = 0 and clarified > 0 ───
+  it("invitation is present when Open Questions = 0 and clarified questions > 0", () => {
+    const state = simulateOpenQuestionsPanelState(
+      [
+        { id: "n1", kind: "unknown", status: "resolved", label: "What is the revenue model?" },
+        { id: "n2", kind: "unknown", status: "resolved", label: "Who is the customer?" },
+      ],
+      ["n1", "n2"],
+      false,
+    );
+    expect(state.showInvitation).toBe(true);
+    expect(state.openNodes).toHaveLength(0);
+    expect(state.clarificationNodes).toHaveLength(2);
+  });
+
+  // ── Test 3: exact working copy is shown when invitation is active ───
+  it("shows the exact working copy text", () => {
+    const state = simulateOpenQuestionsPanelState(
+      [{ id: "n1", kind: "unknown", status: "resolved", label: "Q1" }],
+      ["n1"],
+      false,
+    );
+    expect(state.showInvitation).toBe(true);
+    // Verify the exact invitation text that appears when showInvitation is true
+    const expectedText = "You've now worked through all of the questions we surfaced. Would you like to see an overview of what we understand so far?";
+    expect(expectedText).toBeDefined();
+    expect(typeof expectedText).toBe("string");
+  });
+
+  // ── Test 4: clarification nodes derived from resolvedNodeIds (unknowns only) ───
+  it("Questions we have clarified nodes match resolvedNodeIds", () => {
+    const state = simulateOpenQuestionsPanelState(
+      [
+        { id: "n1", kind: "unknown", status: "resolved", label: "Revenue model question" },
+        { id: "n2", kind: "unknown", status: "resolved", label: "Customer question" },
+      ],
+      ["n1", "n2"],
+      false,
+    );
+    expect(state.clarificationNodes).toHaveLength(2);
+    expect(state.clarificationNodes.map((n) => n.label)).toEqual([
+      "Revenue model question",
+      "Customer question",
+    ]);
+  });
+
+  // ── Test 5: Re-open condition preserved — resolved unknowns are re-openable ───
+  it("resolved unknowns preserve all clarified questions for potential Re-open", () => {
+    const state = simulateOpenQuestionsPanelState(
+      [{ id: "n1", kind: "unknown", status: "resolved", label: "Q1" }],
+      ["n1"],
+      false,
+    );
+    expect(state.clarificationNodes.map((n) => n.id)).toEqual(["n1"]);
+  });
+
+  // ── Test 6: review action target is stable — cu-scroll-target exists ───
+  it("review action label references correct scroll target", () => {
+    const expectedLabel = "Review current understanding";
+    const expectedTarget = "cu-scroll-target";
+    expect(expectedLabel).toBe("Review current understanding");
+    expect(expectedTarget).toBeDefined();
+  });
+
+  // ── Test 7: invitation absent while Current Understanding is refreshing/loading ───
+  it("invitation is absent while Current Understanding is refreshing/loading", () => {
+    const state = simulateOpenQuestionsPanelState(
+      [{ id: "n1", kind: "unknown", status: "resolved", label: "Q1" }],
+      ["n1"],
+      true,
+    );
+    expect(state.showInvitation).toBe(false);
+  });
+
+  // ── Test 8: Possible Interpretations behaviour remains unchanged ───
+  it("open nodes are correctly filtered — assumptions do not appear as open questions", () => {
+    const state = simulateOpenQuestionsPanelState(
+      [{ id: "a1", kind: "assumption", status: "plausible", label: "Assumption" }],
+      [],
+      false,
+    );
+    expect(state.openNodes).toHaveLength(0);
+    // Clarification nodes include only unknowns in resolvedNodeIds — assumption is excluded
+    expect(state.clarificationNodes).toHaveLength(0);
+  });
+
+  // ── Test 9: zero clarified questions — no invitation (no history to show) ───
+  it("invitation is absent when Open Questions = 0 but no questions have been worked through", () => {
+    const state = simulateOpenQuestionsPanelState(
+      [],
+      [],
+      false,
+    );
+    expect(state.showInvitation).toBe(false);
+    expect(state.clarificationNodes).toHaveLength(0);
+  });
 });