confidence-engine/tests/graph/cross-branch-corroboration.test.js

import { describe, expect, it } from "vitest";
import {
  applyValidatedProposal,
  evaluateBranchInteractions,
} from "@/lib/graph/apply-proposal.js";
import { makeEdge, makeGraph, makeNode } from "@/lib/graph/schema.js";

function makeParentWithBranches(children) {
  const parent = makeNode({
    id: "n-parent",
    label: "Explanation for why revenue increased while cash fell",
    description:
      "Need to understand what change or event could explain why these observations differ, because that is needed to investigate their relationship.",
    kind: "unknown",
    status: "unknown",
    confidence: "medium",
  });

  return makeGraph({
    centralStatement: "Revenue increased while cash fell.",
    nodes: [
      parent,
      ...children.map((child) => ({ ...child, parentId: parent.id })),
    ],
    edges: children.map((child, index) =>
      makeEdge({
        id: `e-${index + 1}`,
        fromNodeId: child.id,
        toNodeId: parent.id,
        relationship: "depends_on",
        description: `${child.label} feeds the parent.`,
      }),
    ),
    activeUnknownNodeId: children[0]?.id ?? null,
    resolvedNodeIds: [],
    currentSummary: "cross-branch corroboration fixture",
  });
}

function makeResolvedChild(id, label, value, extra = {}) {
  return makeNode({
    id,
    label,
    description: label,
    kind: "unknown",
    status: "resolved",
    confidence: "medium",
    value,
    evidenceIds: extra.evidenceIds ?? [],
  });
}

function makeUnknownBranch(id, label, description, extra = {}) {
  return makeNode({
    id,
    label,
    description,
    kind: "unknown",
    status: extra.status ?? "unknown",
    confidence: extra.confidence ?? "medium",
    evidenceIds: extra.evidenceIds ?? [],
    value: extra.value ?? null,
  });
}

describe("evaluateBranchInteractions", () => {
  it("detects corroborating independent branches", () => {
    const graph = makeParentWithBranches([
      makeResolvedChild("n-a", "Debtor balance increased", "bank-statement-a", {
        evidenceIds: ["bank-statement-a"],
      }),
      makeResolvedChild(
        "n-b",
        "Cash receipts were delayed",
        "receipts-ledger-b",
        { evidenceIds: ["receipts-ledger-b"] },
      ),
    ]);
    const parentNode = graph.nodes.find((node) => node.id === "n-parent");

    const result = evaluateBranchInteractions({ parentNode, graph });

    expect(result.interactionSummary.corroboratingBranchCount).toBe(1);
    expect(result.interactionSummary.duplicateEvidenceCount).toBe(0);
    expect(result.interactionSummary.conflictingBranchCount).toBe(0);
  });

  it("detects duplicate evidence instead of corroboration", () => {
    const graph = makeParentWithBranches([
      makeResolvedChild(
        "n-a",
        "Bank statement shows increased debtor balance",
        "same-bank",
        {
          evidenceIds: ["same-bank"],
        },
      ),
      makeResolvedChild(
        "n-b",
        "Delayed receipts also cite the bank statement",
        "same-bank",
        {
          evidenceIds: ["same-bank"],
        },
      ),
    ]);
    const parentNode = graph.nodes.find((node) => node.id === "n-parent");

    const result = evaluateBranchInteractions({ parentNode, graph });

    expect(result.interactionSummary.duplicateEvidenceCount).toBe(1);
    expect(result.interactionSummary.corroboratingBranchCount).toBe(0);
  });

  it("detects conflicting branches", () => {
    const graph = makeParentWithBranches([
      makeResolvedChild("n-a", "Revenue recognised correctly", "correctly"),
      makeNode({
        id: "n-b",
        label: "Revenue recognised incorrectly",
        description: "Revenue recognised incorrectly",
        kind: "unknown",
        status: "contradicted",
        confidence: "medium",
        value: "incorrectly",
      }),
    ]);
    const parentNode = graph.nodes.find((node) => node.id === "n-parent");

    const result = evaluateBranchInteractions({ parentNode, graph });

    expect(result.interactionSummary.conflictingBranchCount).toBe(1);
  });
});

describe("cross-branch corroboration effects", () => {
  function applyToGraph(children, resolvedIds, contradictedIds = []) {
    const graph = makeParentWithBranches(children);
    return applyValidatedProposal({
      situationGraph: graph,
      proposal: {
        addedNodes: [
          makeNode({
            id: "n-anchor",
            label: "Update anchor",
            description:
              "Anchor state introduced by the answer because the update must contain a meaningful change.",
            kind: "state",
            status: "known",
            confidence: "low",
          }),
        ],
        updatedNodes: [
          ...resolvedIds.map((id) => ({
            nodeId: id,
            previousStatus: "unknown",
            newStatus: "resolved",
            previousValue: null,
            newValue: `answer:${id}`,
            reason: "resolved child",
          })),
          ...contradictedIds.map((id) => ({
            nodeId: id,
            previousStatus: "unknown",
            newStatus: "contradicted",
            previousValue: null,
            newValue: `contradiction:${id}`,
            reason: "contradicted child",
          })),
        ],
        addedEdges: [],
        removedEdgeIds: [],
        resolvedUnknownNodeIds: resolvedIds,
        affectedNodeIds: [],
        selectedQuestion: null,
      },
      previousQuestion: "What evidence would clarify this branch?",
      answer: "deterministic branch update",
    });
  }

  it("independent corroboration increases justified confidence without reaching high on incomplete parent", () => {
    const result = applyToGraph(
      [
        makeUnknownBranch(
          "n-a",
          "Debtor balance increased",
          "Debtor balance increased",
        ),
        makeUnknownBranch(
          "n-b",
          "Cash receipts delayed",
          "Cash receipts delayed",
        ),
        makeUnknownBranch(
          "n-c",
          "Possible one-off event during the period",
          "Possible one-off event during the period",
        ),
        makeUnknownBranch(
          "n-d",
          "Whether the two observations reflect different timing",
          "Whether the two observations reflect different timing",
        ),
      ],
      ["n-a", "n-b"],
    );

    expect(result.success).toBe(true);
    expect(result.interactionSummary?.corroboratingBranchCount).toBeGreaterThan(
      0,
    );
    expect(result.interactionSummary?.duplicateEvidenceCount).toBe(0);
    expect(result.parentConfidenceAfter).toBe("medium");
    expect(result.confidenceCapReason).toBe(
      "independent_corroboration_with_incomplete_parent",
    );
  });

  it("duplicate evidence does not increase confidence", () => {
    const result = applyToGraph(
      [
        makeUnknownBranch(
          "n-a",
          "Bank statement shows increased debtor balance",
          "Bank statement shows increased debtor balance",
          { evidenceIds: ["same-bank"] },
        ),
        makeUnknownBranch(
          "n-b",
          "Delayed receipts also cite the bank statement",
          "Delayed receipts also cite the bank statement",
          { evidenceIds: ["same-bank"] },
        ),
        makeUnknownBranch(
          "n-c",
          "Possible one-off event during the period",
          "Possible one-off event during the period",
        ),
      ],
      ["n-a", "n-b"],
    );

    expect(result.success).toBe(true);
    expect(result.interactionSummary?.duplicateEvidenceCount).toBeGreaterThan(
      0,
    );
    expect(result.interactionSummary?.corroboratingBranchCount).toBe(0);
    expect(result.confidenceCapReason).toBe(
      "duplicate_evidence_no_extra_confidence",
    );
  });

  it("conflicting evidence caps confidence", () => {
    const result = applyToGraph(
      [
        makeUnknownBranch(
          "n-a",
          "Revenue recognised correctly",
          "Revenue recognised correctly",
        ),
        makeUnknownBranch(
          "n-b",
          "Revenue recognised incorrectly",
          "Revenue recognised incorrectly",
        ),
        makeUnknownBranch(
          "n-c",
          "Possible one-off event during the period",
          "Possible one-off event during the period",
        ),
      ],
      ["n-a"],
      ["n-b"],
    );

    expect(result.success).toBe(true);
    expect(result.interactionSummary?.conflictingBranchCount).toBeGreaterThan(
      0,
    );
    expect(result.conclusionConfidenceAfter).toBe("low");
  });

  it("independent branches stay interaction-neutral", () => {
    const result = applyToGraph(
      [
        makeUnknownBranch(
          "n-a",
          "Marketing campaign changed traffic",
          "Marketing campaign changed traffic",
        ),
        makeUnknownBranch(
          "n-b",
          "Equipment maintenance occurred",
          "Equipment maintenance occurred",
        ),
      ],
      ["n-a"],
    );

    expect(result.success).toBe(true);
    expect(result.interactionSummary?.independentBranchCount).toBeGreaterThan(
      0,
    );
  });
});