feat(ask): honor optional knowledge cutoff on Global Ask

AGENTS.md

@@ -332,6 +332,9 @@ v0.88.0). Do not invent a theta.
 Opening a cutoff-rewritten title shows **Body this run knew** from
 `source_post_revision` beside the live rewrite (ADR 0025 / v2.1.0).
 Do not invent the earlier sentence when no revision covers the cutoff.
+Global Ask uses the same revision cover when `knowledge_cutoff` is set
+(ADR 0216 / #271); omit the field to keep the live-query contract, and
+never substitute a live body for a missing historical cover.
 
 A corporate-entity similarity result has three outcomes: unique, miss,
 or tie (ADR 0026). A tie is not a miss. Keep the organization name

ARCHITECTURE.md

@@ -240,7 +240,9 @@ Each direct edge includes `interval_relation_code` /
 `interval_relation_label` computed from the posts' observed windows.
 Global Ask merges cited threads from one post/edge fetch pair and
 caps the payload at the landing node bound, keeping cited posts first
-(ADR 0169). Open a cited post to read the focused thread.
+(ADR 0169). Optional `knowledge_cutoff` on `POST /api/ask` selects the
+covering `source_post_revision` and never substitutes a live body
+(ADR 0216). Open a cited post to read the focused thread.
 `POST /api/lineage/rebuild` (`post_admin`) re-runs `reconstruct()` over
 every `source_post` and atomically rewrites edges, channel signals, and
 Allen interval relations. Reconstruct grouping is

CHANGELOG.d/2.19.0-global-ask-knowledge-cutoff.md

@@ -0,0 +1,6 @@
+# 2.19.0 Global Ask knowledge cutoff
+
+Ask Agent now accepts an optional UTC knowledge cutoff. Dated questions use
+the retained source-post revision from that clock, never the live rewrite,
+and say when a historical body was not kept. Leaving the cutoff blank keeps
+the live-query contract.

CHANGELOG.md

@@ -8,7 +8,6 @@ All notable changes to this project are documented here. Format follows
 
 ### Added
 
-
 - Expanded Voice-of-X post taxonomy (ADR 0246): the governed `voc_type`
   scheme adds Voice of Supplier, Employee, Business, Regulator, Investor,
   Society, and Process as source-post categories. Ontology SKOS concepts and
@@ -63,6 +62,11 @@ All notable changes to this project are documented here. Format follows
   deterministic application read
   model (`lineageweave.worker_function_taxonomy`) exposes fail-closed
   lookups; ranks are scale positions and are never used as weights.
+=======
+- Global Ask accepts an optional UTC `knowledge_cutoff`. Dated questions
+  retrieve only posts available by that clock, cite the retained
+  `source_post_revision`, and name when a historical body was not kept.
+  Omitting the cutoff keeps the live-query contract (ADR 0216 / #271).
 - Persist explicit paragraph, list, table, MathML formula, and caller-parsed
   conversation-turn semantic-unit kinds without inferring absent boundaries.
 - Event Lineage now persists each reconstructed connection's independent

CLAUDE.md

@@ -42,7 +42,8 @@ Opening a cutoff-rewritten title shows **Body this run knew** from
 `source_post_revision` beside the live rewrite, with both clocks named.
 Compare those two texts before treating the live body as reconstructed
 evidence; do not invent an earlier sentence when no revision covers the
-cutoff.
+cutoff. Global Ask optional `knowledge_cutoff` uses the same cover
+(ADR 0216).
 
 ## Where the rest lives
 

backend/app/main.py

@@ -3161,6 +3161,9 @@ async def ask_agent(
     polls ``GET /api/ask/jobs/{id}`` for the settled answer. Submission
     still fails fast on the states that cannot ever succeed (blank
     question, missing permission, unconfigured orchestrator).
+
+    Optional ``knowledge_cutoff`` selects retained evidence available at
+    that clock. Omitting it keeps the live-query contract (ADR 0216).
     """
     return await submit_global_ask(
         pool=pool,

backend/app/post_chat_ingestion.py

@@ -216,7 +216,6 @@ def _seoul_today() -> date:
 
 _POST_CHAT_CANDIDATE_LIMIT = 32
 
-
 def _source_hint_facts(row: Any) -> tuple[str, ...]:
     """Render raw source fields as explicitly weak, column-level evidence."""
     facts: list[str] = []
@@ -834,6 +833,8 @@ async def gather_global_chat_sources(
     # `find_linked_post_ids`'s `.direct` set used by the post-scoped chat
     # flow. Only the top match is expanded so lower-ranked semantic candidates
     # cannot each pull a separate lineage chain into the bounded context.
+    # Cutoff answers skip this expansion: reconstructed edges have no
+    # available-time contract and must not leak later neighbors (ADR 0216).
     lineage_neighbor_ids: list[str] = []
     lineage_anchor_id = candidate_ids[0] if candidate_ids else None
     if lineage_anchor_id and knowledge_cutoff is None:

backend/app/source_post_revision.py

@@ -100,7 +100,7 @@ async def fetch_known_at_revisions(
 ) -> dict[str, dict[str, str]]:
     """Batch-load the retained revision covering ``as_of`` for each post.
 
-    Missing posts stay absent so callers can report an honest historical-body
+    Missing covers are omitted so callers can report an honest historical-body
     limitation without substituting the live title or body.
     """
 

frontend/src/App.test.tsx

@@ -2,6 +2,7 @@ import { fireEvent, render, screen, waitFor, within } from "@testing-library/rea
 import userEvent from "@testing-library/user-event";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import App from "./App";
+import { optionalKnowledgeCutoffIso } from "./api";
 import { setLocale } from "./i18n";
 import { OIDC_RETURN_URL_STORAGE_KEY } from "./oidcReturnUrl";
 
@@ -27,6 +28,16 @@ beforeEach(() => {
   };
 });
 
+it("normalizes valid knowledge cutoffs and rejects invalid input", () => {
+  expect(optionalKnowledgeCutoffIso("")).toBeUndefined();
+  expect(optionalKnowledgeCutoffIso("2026-01-15T12:00")).toBe(
+    new Date("2026-01-15T12:00").toISOString(),
+  );
+  expect(() => optionalKnowledgeCutoffIso("not-a-date")).toThrow(
+    "invalid knowledge cutoff",
+  );
+});
+
 afterEach(() => {
   vi.unstubAllGlobals();
   window.history.replaceState({}, "", "/");
@@ -1971,6 +1982,35 @@ describe("App, authenticated", () => {
     expect(screen.queryByText(/ontology_iri|contextual_orchestrator/i)).not.toBeInTheDocument();
   });
 
+  it("converts the local knowledge cutoff to UTC for Global Ask", async () => {
+    const fetchMock = stubBackend();
+    render(<App />);
+    expect(await screen.findByRole("button", { name: "View post: Public post" })).toBeInTheDocument();
+    await userEvent.click(screen.getByRole("button", { name: "Ask Agent" }));
+    expect(screen.getByLabelText("Use evidence available by (optional)")).toBeInTheDocument();
+    expect(screen.getByText("Choose a time on this device, or leave blank to use the latest evidence.")).toBeInTheDocument();
+    await userEvent.type(screen.getByRole("textbox", { name: "Ask a question" }), "Phoenix?");
+    await userEvent.type(
+      screen.getByLabelText("Use evidence available by (optional)"),
+      "2026-01-15T12:00",
+    );
+    await userEvent.click(screen.getByRole("button", { name: "Ask" }));
+    expect(
+      await screen.findByText("The cited project is supported by the stored semantic evidence."),
+    ).toBeInTheDocument();
+    const askCall = fetchMock.mock.calls.find(
+      ([input, init]) => String(input).endsWith("/api/ask") && (init as RequestInit | undefined)?.method === "POST",
+    );
+    expect(askCall).toBeTruthy();
+    const askInit = askCall?.[1] as RequestInit | undefined;
+    expect(askInit).toBeDefined();
+    expect(JSON.parse(String(askInit?.body))).toEqual({
+      question: "Phoenix?",
+      verify_external: false,
+      knowledge_cutoff: new Date("2026-01-15T12:00").toISOString(),
+    });
+  });
+
   it("localizes Ask delivery copy instead of rendering Korean literals in English", async () => {
     stubBackend({ askDelivery: true });
     render(<App />);

frontend/src/App.tsx

@@ -8,6 +8,7 @@ import { useAuth } from "react-oidc-context";
 import {
   askPostChat,
   askAgent,
+  optionalKnowledgeCutoffIso,
   BackendError,
   createAnalysisRun,
   startAnalysisRun,
@@ -4830,11 +4831,11 @@ export function AskAgentPanel({
   onOpenPost: (postId: string) => void;
 }) {
   const [question, setQuestion] = useState("");
+  const [knowledgeCutoff, setKnowledgeCutoff] = useState("");
   const [answer, setAnswer] = useState<AskAgentResponse | null>(null);
   const [error, setError] = useState<string | null>(null);
   const [asking, setAsking] = useState(false);
   const [verifyExternal, setVerifyExternal] = useState(false);
-  const [knowledgeCutoff, setKnowledgeCutoff] = useState("");
   const [evidenceLayerPostId, setEvidenceLayerPostId] = useState<string | null>(null);
   const now = new Date();
   const localKnowledgeCutoffMax = new Date(
@@ -4844,6 +4845,14 @@ export function AskAgentPanel({
   async function handleAsk() {
     const normalized = question.trim();
     if (!normalized) return;
+    let cutoff: string | undefined;
+    try {
+      cutoff = optionalKnowledgeCutoffIso(knowledgeCutoff);
+    } catch {
+      setAnswer(null);
+      setError(t("Enter a valid knowledge cutoff, then ask again."));
+      return;
+    }
     setAsking(true);
     setError(null);
     try {
@@ -4852,7 +4861,7 @@ export function AskAgentPanel({
           accessToken,
           normalized,
           verifyExternal,
-          knowledgeCutoff ? new Date(knowledgeCutoff).toISOString() : undefined,
+          cutoff,
         ),
       );
     } catch (err) {
@@ -4888,13 +4897,15 @@ export function AskAgentPanel({
           <span>{t("Check eligible public claims")}</span>
         </label>
         <label className="ask-agent-field">
-          <span>{t("Knowledge cutoff (optional)")}</span>
+          <span>{t("Use evidence available by (optional)")}</span>
           <input
             type="datetime-local"
+            aria-label={t("Use evidence available by (optional)")}
             value={knowledgeCutoff}
             max={localKnowledgeCutoffMax}
             onChange={(event) => setKnowledgeCutoff(event.target.value)}
           />
+          <small>{t("Choose a time on this device, or leave blank to use the latest evidence.")}</small>
         </label>
         <button className="btn-primary" onClick={() => void handleAsk()} disabled={asking || !question.trim()}>
           {asking ? t("Asking...") : t("Ask")}
@@ -4911,7 +4922,7 @@ export function AskAgentPanel({
                 {answer.grounding_status === "fully_cutoff_grounded"
                   ? t("Fully cutoff-grounded")
                   : t("Partially cutoff-grounded")}
-                {` · ${answer.knowledge_cutoff}`}
+                {` · ${new Date(answer.knowledge_cutoff).toLocaleString()}`}
               </p>
               {answer.limitations?.length ? (
                 <p role="alert">
@@ -4952,6 +4963,9 @@ export function AskAgentPanel({
                         </span>
                       ) : null}
                     </button>
+                    {post.historical_body_unavailable ? (
+                      <p className="post-meta">{t("Historical body unavailable")}</p>
+                    ) : null}
                     <button
                       type="button"
                       className="citation-chip"

frontend/src/AskAgentCutoff.stories.tsx

@@ -48,7 +48,10 @@ export const PartialHistoricalEvidence: Story = {
   play: async ({ canvasElement }) => {
     const canvas = within(canvasElement);
     await userEvent.type(canvas.getByLabelText("Ask a question"), "What was known about Apollo?");
-    await userEvent.type(canvas.getByLabelText("Knowledge cutoff (optional)"), "2026-01-15T12:00");
+    await userEvent.type(
+      canvas.getByLabelText("Use evidence available by (optional)"),
+      "2026-01-15T12:00",
+    );
     await userEvent.click(canvas.getByRole("button", { name: "Ask" }));
     await expect(canvas.findByText(/Partially cutoff-grounded/)).resolves.toBeVisible();
     await expect(canvas.getByRole("alert")).toHaveTextContent("Current-only semantic channels were excluded");

frontend/src/AskAgentPanel.test.tsx

@@ -79,7 +79,7 @@ describe("AskAgentPanel public verification", () => {
       screen.getByRole("checkbox", { name: "Check eligible public claims" }),
     );
     await userEvent.type(
-      screen.getByLabelText("Knowledge cutoff (optional)"),
+      screen.getByLabelText("Use evidence available by (optional)"),
       "2026-01-15T12:00",
     );
     await userEvent.click(screen.getByRole("button", { name: "Ask" }));

frontend/src/api.ts

@@ -1200,6 +1200,16 @@ interface AskJobStatus {
   failure_detail?: string | null;
 }
 
+export function optionalKnowledgeCutoffIso(value: string): string | undefined {
+  const input = value.trim();
+  if (!input) return undefined;
+  const parsed = new Date(input);
+  if (Number.isNaN(parsed.getTime())) {
+    throw new RangeError("invalid knowledge cutoff");
+  }
+  return parsed.toISOString();
+}
+
 /** Submit the question as an asynchronous job and poll it to completion.
  * The signature and resolved value are unchanged from the old synchronous
  * call, so callers (AskAgentPanel) keep their existing pending/complete

frontend/src/i18n.ts

@@ -187,6 +187,10 @@ const TRANSLATIONS: Partial<Record<Locale, Record<string, string>>> = {
     "Ask a question": "질문 입력",
     "Check eligible public claims": "검증 가능한 공개 주장을 확인",
     "Knowledge cutoff (optional)": "지식 컷오프(선택)",
+    "Use evidence available by (optional)": "이 시점까지 사용 가능한 근거 사용(선택)",
+    "Choose a time on this device, or leave blank to use the latest evidence.": "이 기기의 시간을 선택하거나, 최신 근거를 사용하려면 비워 두세요.",
+    "Historical body unavailable": "해당 시점의 본문을 사용할 수 없습니다",
+    "Enter a valid knowledge cutoff, then ask again.": "올바른 지식 컷오프를 입력한 뒤 다시 질문하세요.",
     "Knowledge-cutoff grounding": "지식 컷오프 근거 상태",
     "Fully cutoff-grounded": "컷오프 시점 근거로 완전히 구성됨",
     "Partially cutoff-grounded": "컷오프 시점 근거로 일부만 구성됨",
@@ -724,6 +728,10 @@ const TRANSLATIONS: Partial<Record<Locale, Record<string, string>>> = {
     "Ask a question": "输入问题",
     "Check eligible public claims": "核验符合条件的公开声明",
     "Knowledge cutoff (optional)": "知识截止时间（可选）",
+    "Use evidence available by (optional)": "使用截至此时间可用的证据（可选）",
+    "Choose a time on this device, or leave blank to use the latest evidence.": "选择此设备上的时间，或留空以使用最新证据。",
+    "Historical body unavailable": "该时间点的正文不可用",
+    "Enter a valid knowledge cutoff, then ask again.": "请输入有效的知识截止时间，然后重新提问。",
     "Knowledge-cutoff grounding": "知识截止依据状态",
     "Fully cutoff-grounded": "完全基于截止时间证据",
     "Partially cutoff-grounded": "部分基于截止时间证据",
@@ -1277,6 +1285,10 @@ const TRANSLATIONS: Partial<Record<Locale, Record<string, string>>> = {
     "Ask a question": "質問を入力",
     "Check eligible public claims": "対象となる公開主張を検証",
     "Knowledge cutoff (optional)": "知識カットオフ（任意）",
+    "Use evidence available by (optional)": "この時点までに利用可能な証拠を使用（任意）",
+    "Choose a time on this device, or leave blank to use the latest evidence.": "この端末の時刻を選択するか、最新の証拠を使用する場合は空欄にしてください。",
+    "Historical body unavailable": "指定時点の本文は利用できません",
+    "Enter a valid knowledge cutoff, then ask again.": "有効な知識カットオフを入力して、もう一度質問してください。",
     "Knowledge-cutoff grounding": "知識カットオフ根拠状態",
     "Fully cutoff-grounded": "カットオフ時点の根拠で完全に構成",
     "Partially cutoff-grounded": "カットオフ時点の根拠で部分的に構成",
@@ -1809,6 +1821,10 @@ const TRANSLATIONS: Partial<Record<Locale, Record<string, string>>> = {
     "Ask a question": "Nhập câu hỏi",
     "Check eligible public claims": "Kiểm tra các tuyên bố công khai đủ điều kiện",
     "Knowledge cutoff (optional)": "Mốc cắt tri thức (tùy chọn)",
+    "Use evidence available by (optional)": "Dùng bằng chứng có sẵn đến thời điểm này (tùy chọn)",
+    "Choose a time on this device, or leave blank to use the latest evidence.": "Chọn thời gian trên thiết bị này, hoặc để trống để dùng bằng chứng mới nhất.",
+    "Historical body unavailable": "Nội dung tại thời điểm đó không khả dụng",
+    "Enter a valid knowledge cutoff, then ask again.": "Nhập mốc cắt tri thức hợp lệ rồi đặt câu hỏi lại.",
     "Knowledge-cutoff grounding": "Trạng thái căn cứ theo mốc cắt tri thức",
     "Fully cutoff-grounded": "Được căn cứ đầy đủ tại mốc cắt",
     "Partially cutoff-grounded": "Được căn cứ một phần tại mốc cắt",

lineageweave/post_chat.py

@@ -90,6 +90,7 @@ def cited_post_summaries(
 
     The sliding evidence chip must show the source post's title, not a
     truncated UUID -- a missing title is omitted, never invented.
+    Cutoff citations also name the retained revision and limitation flags.
     """
     by_id = {source.post_id: source for source in sources}
     citations: list[dict[str, str | bool | list[str] | None]] = []
@@ -157,6 +158,7 @@ def _buyer_evidence_kind(fact: str) -> str:
     return "source_field"
 
 
+
 def _buyer_evidence_text(fact: str) -> str:
     cleaned = re.sub(r"\s*\|\s*(?:ontology_iri|extraction_method|confidence):\s*[^|\[]+", "", fact)
     cleaned = re.sub(r"\s*\[provenance=[^]]+\]", "", cleaned)

tests/test_global_ask_sources.py

@@ -117,6 +117,7 @@ class FakeConnection:
         async def fetch(self, query: str, *args):
             if "unit_similarity" in query:
                 assert "authorized_evidence_candidates" in query
+                assert "$9::timestamptz" not in query
                 assert query.index("authorized_evidence_candidates") < query.rindex("limit $8")
                 assert args[8] == ["exclusive responsibility"]
                 return [
@@ -209,6 +210,7 @@ async def fetch(self, query: str, *args):
 
     source_query, source_args = calls[-1]
     assert "process_unit_id::text = any($2::text[])" in source_query
+    assert source_query.count("created_at <= $7") == 1
     assert source_args[:2] == (["corp-demo"], ["process-demo"])
 
 

tests/test_source_post_revision.py

@@ -3,7 +3,11 @@
 from datetime import datetime, timezone
 from pathlib import Path
 
-from backend.app.source_post_revision import parse_as_of_clock, revision_covers_clock
+from backend.app.source_post_revision import (
+    fetch_known_at_revisions,
+    parse_as_of_clock,
+    revision_covers_clock,
+)
 
 _ROOT = Path(__file__).resolve().parents[1]
 _MIGRATION = _ROOT / "migrations" / "0024_source_post_revision.sql"
@@ -59,3 +63,13 @@ def test_revision_migration_records_title_or_body_rewrites_only() -> None:
     assert seed.index("0024_source_post_revision.sql") < seed.index(
         "0025_role_person_catalog_identity.sql"
     )
+
+
+def test_batch_revision_lookup_omits_missing_covers() -> None:
+    import inspect
+
+    source = inspect.getsource(fetch_known_at_revisions)
+    assert "source_post_revision" in source
+    assert "written_at <= $2" in source
+    assert "superseded_at is null or superseded_at > $2" in source
+    assert "never a live body" in source.lower() or "Missing covers are omitted" in source