feat: add configurable context visibility

src/security/context-visibility.test.ts

@@ -0,0 +1,95 @@
+import { describe, expect, it } from "vitest";
+import {
+  evaluateSupplementalContextVisibility,
+  filterSupplementalContextItems,
+  shouldIncludeSupplementalContext,
+} from "./context-visibility.js";
+
+describe("evaluateSupplementalContextVisibility", () => {
+  it("reports why all mode keeps context", () => {
+    expect(
+      evaluateSupplementalContextVisibility({
+        mode: "all",
+        kind: "history",
+        senderAllowed: false,
+      }),
+    ).toEqual({
+      include: true,
+      reason: "mode_all",
+    });
+  });
+
+  it("reports quote override decisions", () => {
+    expect(
+      evaluateSupplementalContextVisibility({
+        mode: "allowlist_quote",
+        kind: "quote",
+        senderAllowed: false,
+      }),
+    ).toEqual({
+      include: true,
+      reason: "quote_override",
+    });
+  });
+});
+
+describe("shouldIncludeSupplementalContext", () => {
+  it("keeps all context in all mode", () => {
+    expect(
+      shouldIncludeSupplementalContext({
+        mode: "all",
+        kind: "history",
+        senderAllowed: false,
+      }),
+    ).toBe(true);
+  });
+
+  it("enforces allowlist mode for non-allowlisted senders", () => {
+    expect(
+      shouldIncludeSupplementalContext({
+        mode: "allowlist",
+        kind: "thread",
+        senderAllowed: false,
+      }),
+    ).toBe(false);
+  });
+
+  it("keeps explicit quotes in allowlist_quote mode", () => {
+    expect(
+      shouldIncludeSupplementalContext({
+        mode: "allowlist_quote",
+        kind: "quote",
+        senderAllowed: false,
+      }),
+    ).toBe(true);
+  });
+
+  it("still drops non-quote context in allowlist_quote mode", () => {
+    expect(
+      shouldIncludeSupplementalContext({
+        mode: "allowlist_quote",
+        kind: "history",
+        senderAllowed: false,
+      }),
+    ).toBe(false);
+  });
+});
+
+describe("filterSupplementalContextItems", () => {
+  it("filters blocked items and reports omission count", () => {
+    const result = filterSupplementalContextItems({
+      items: [
+        { id: "allowed", senderAllowed: true },
+        { id: "blocked", senderAllowed: false },
+      ],
+      mode: "allowlist",
+      kind: "thread",
+      isSenderAllowed: (item) => item.senderAllowed,
+    });
+
+    expect(result).toEqual({
+      items: [{ id: "allowed", senderAllowed: true }],
+      omitted: 1,
+    });
+  });
+});

src/security/context-visibility.ts

@@ -0,0 +1,58 @@
+import type { ContextVisibilityMode } from "../config/types.base.js";
+
+export type ContextVisibilityKind = "history" | "thread" | "quote" | "forwarded";
+
+export type ContextVisibilityDecisionReason =
+  | "mode_all"
+  | "sender_allowed"
+  | "quote_override"
+  | "blocked";
+
+export type ContextVisibilityDecision = {
+  include: boolean;
+  reason: ContextVisibilityDecisionReason;
+};
+
+export function evaluateSupplementalContextVisibility(params: {
+  mode: ContextVisibilityMode;
+  kind: ContextVisibilityKind;
+  senderAllowed: boolean;
+}): ContextVisibilityDecision {
+  if (params.mode === "all") {
+    return { include: true, reason: "mode_all" };
+  }
+  if (params.senderAllowed) {
+    return { include: true, reason: "sender_allowed" };
+  }
+  if (params.mode === "allowlist_quote" && params.kind === "quote") {
+    return { include: true, reason: "quote_override" };
+  }
+  return { include: false, reason: "blocked" };
+}
+
+export function shouldIncludeSupplementalContext(params: {
+  mode: ContextVisibilityMode;
+  kind: ContextVisibilityKind;
+  senderAllowed: boolean;
+}): boolean {
+  return evaluateSupplementalContextVisibility(params).include;
+}
+
+export function filterSupplementalContextItems<T>(params: {
+  items: readonly T[];
+  mode: ContextVisibilityMode;
+  kind: ContextVisibilityKind;
+  isSenderAllowed: (item: T) => boolean;
+}): { items: T[]; omitted: number } {
+  const items = params.items.filter((item) =>
+    shouldIncludeSupplementalContext({
+      mode: params.mode,
+      kind: params.kind,
+      senderAllowed: params.isSenderAllowed(item),
+    }),
+  );
+  return {
+    items,
+    omitted: params.items.length - items.length,
+  };
+}