Add evidence-aware retrieval responses

README.md

@@ -2,11 +2,10 @@
 
 BridgeAI helps families turn scattered school announcements into sourced answers, deadlines, and next steps. It indexes announcements locally, retrieves the best supporting passages, extracts action items, and refuses to sound certain when the source coverage is weak.
 
-Current state: ingestion, ranked retrieval, citations, confidence scoring, deadline extraction, English/Spanish query normalization, HTTP API, demo UI, and tests are working. Live district connectors are intentionally not included yet.
+Current state: ingestion, ranked retrieval, sentence-level evidence mapped to citations, conflicting-date detection, confidence scoring, deadline extraction, English/Spanish query normalization, HTTP API, demo UI, and tests are working. Live district connectors are intentionally not included yet.
 
 ```bash
 npm test
 npm start
 # open http://localhost:8080
 ```
-

src/index.js

@@ -1,4 +1,4 @@
-import {extractActions, normalize, sentences} from "./text.js";
+import {extractActions, extractDates, normalize, sentences} from "./text.js";
 
 export class KnowledgeIndex {
   constructor() {
@@ -69,27 +69,58 @@ export function answer(index, question, now = new Date()) {
       overlap: normalize(candidate.sentence).filter(token => queryTokens.has(token)).length
     }))
     .sort((a, b) => b.overlap - a.overlap || b.result.score - a.result.score)
+    .filter(candidate => candidate.overlap > 0)
     .slice(0, 3);
-  const citations = [...new Map(selected.map(({result}) => [result.documentId, {
-    id: result.documentId,
-    title: result.source.title,
-    url: result.source.url,
-    publishedAt: result.source.publishedAt,
-    passage: result.id
-  }])).values()];
+  if (!selected.length) {
+    return {answer: "I could not find a source that answers that yet.", confidence: 0.08, citations: [], evidence: [], actions: [], conflicts: []};
+  }
+  const citationByDocument = new Map();
+  for (const {result} of selected) {
+    if (!citationByDocument.has(result.documentId)) citationByDocument.set(result.documentId, {
+      id: result.documentId,
+      title: result.source.title,
+      url: result.source.url,
+      publishedAt: result.source.publishedAt,
+      passage: result.id
+    });
+  }
+  const citations = [...citationByDocument.values()];
+  const citationNumber = new Map(citations.map((citation, index) => [citation.id, index + 1]));
+  const evidence = selected.map(({sentence, result}) => ({
+    statement: sentence,
+    citation: citationNumber.get(result.documentId),
+    passage: result.id,
+    score: Number(result.score.toFixed(3))
+  }));
   const coverage = Math.min(1, new Set(results.flatMap(result => result.tokens.filter(token => queryTokens.has(token)))).size / queryTokens.size);
   const corroboration = Math.min(1, new Set(results.map(result => result.documentId)).size / 2);
   const topStrength = Math.min(1, results[0].score / 5);
-  const confidence = Number((0.55 * coverage + 0.25 * corroboration + 0.2 * topStrength).toFixed(2));
+  const conflicts = findDateConflicts(evidence);
+  const confidence = Number(Math.max(0.05, 0.55 * coverage + 0.25 * corroboration + 0.2 * topStrength - 0.2 * conflicts.length).toFixed(2));
   const prefix = confidence < 0.45 ? "The available announcement suggests: " : "Based on the school announcements: ";
   return {
-    answer: prefix + selected.map(({sentence}, index) => `${sentence} [${index + 1}]`).join(" "),
+    answer: prefix + evidence.map(item => `${item.statement} [${item.citation}]`).join(" "),
     confidence,
     citations,
+    evidence,
+    conflicts,
     actions: extractActions(selected.map(item => item.sentence).join(" "))
   };
 }
 
+function findDateConflicts(evidence) {
+  const dates = new Map();
+  for (const item of evidence) {
+    for (const value of extractDates(item.statement)) {
+      const key = value.toLowerCase();
+      if (!dates.has(key)) dates.set(key, new Set());
+      dates.get(key).add(item.citation);
+    }
+  }
+  if (dates.size < 2) return [];
+  return [{type: "date", values: [...dates.entries()].map(([value, sources]) => ({value, citations: [...sources]}))}];
+}
+
 function frequency(tokens) {
   const values = new Map();
   for (const token of tokens) values.set(token, (values.get(token) ?? 0) + 1);
@@ -101,4 +132,3 @@ function chunk(values, size) {
   for (let i = 0; i < values.length; i += size) output.push(values.slice(i, i + size));
   return output;
 }
-

test/index.test.js

@@ -39,3 +39,18 @@ test("action extraction keeps associated dates", () => {
   assert.deepEqual(actions[0].dates, ["August 18, 2026"]);
 });
 
+test("each answer marker points to its supporting source and conflicts lower confidence", () => {
+  const index = fixture();
+  index.add({
+    id:"reminder", title:"Registration reminder", url:"https://example.test/reminder",
+    publishedAt:"2026-08-02", authority:.8,
+    body:"Families should register online. Registration closes August 20, 2026."
+  });
+  const result = answer(index, "When does registration close?", new Date("2026-08-04"));
+  assert.equal(result.evidence.length, 2);
+  for (const item of result.evidence) {
+    assert.equal(item.passage.split("#")[0], result.citations[item.citation - 1].id);
+  }
+  assert.equal(result.conflicts[0].type, "date");
+  assert.ok(result.confidence < .8);
+});