diff --git a/src/lib/__tests__/testService.test.js b/src/lib/__tests__/testService.test.js
index 51e2447..3cbdd66 100644
--- a/src/lib/__tests__/testService.test.js
+++ b/src/lib/__tests__/testService.test.js
@@ -19,7 +19,10 @@ vi.mock('../db', () => ({
   getCurriculum: vi.fn(),
 }));
 
-vi.mock('../llm', () => ({ callLLM: (...args) => callLLMMock(...args) }));
+vi.mock('../llm', () => ({
+  callLLM: (...args) => callLLMMock(...args),
+  cachedSystem: (text) => [{ type: 'text', text }],
+}));
 vi.mock('../curriculumService', () => ({
   getCurriculumTopic: vi.fn(async () => ({ topic: null })),
   getQuarterForWeek: vi.fn(() => 1),
diff --git a/src/lib/db.js b/src/lib/db.js
index 7e81c05..7c91242 100644
--- a/src/lib/db.js
+++ b/src/lib/db.js
@@ -1,5 +1,15 @@
 import { pb } from './pb';
 
+// Upsert helper: update existing record if found, otherwise create.
+async function pbUpsert(collection, filter, updateData, createData) {
+  try {
+    const r = await pb.collection(collection).getFirstListItem(filter);
+    return pb.collection(collection).update(r.id, updateData);
+  } catch {
+    return pb.collection(collection).create(createData);
+  }
+}
+
 // ── Topics ──────────────────────────────────────────────────────────────────
 
 export async function getTopics() {
@@ -72,13 +82,8 @@ export async function getContent(topicId) {
   } catch { return null; }
 }
 
-export async function setContent(topicId, data) {
-  try {
-    const r = await pb.collection('content').getFirstListItem(`topic_id="${topicId}"`);
-    return pb.collection('content').update(r.id, { data });
-  } catch {
-    return pb.collection('content').create({ topic_id: topicId, data });
-  }
+export function setContent(topicId, data) {
+  return pbUpsert('content', `topic_id="${topicId}"`, { data }, { topic_id: topicId, data });
 }
 
 export async function deleteContent(topicId) {
@@ -102,13 +107,8 @@ export async function getQuizBank(topicId) {
   } catch { return []; }
 }
 
-export async function setQuizBank(topicId, questions) {
-  try {
-    const r = await pb.collection('quiz_banks').getFirstListItem(`topic_id="${topicId}"`);
-    return pb.collection('quiz_banks').update(r.id, { questions });
-  } catch {
-    return pb.collection('quiz_banks').create({ topic_id: topicId, questions });
-  }
+export function setQuizBank(topicId, questions) {
+  return pbUpsert('quiz_banks', `topic_id="${topicId}"`, { questions }, { topic_id: topicId, questions });
 }
 
 export async function deleteQuestionFromBank(topicId, questionId) {
@@ -186,17 +186,10 @@ export async function getCachedQuiz(userId, weekNumber) {
   } catch { return null; }
 }
 
-export async function setCachedQuiz(userId, weekNumber, quiz) {
-  try {
-    const r = await pb.collection('quiz_cache').getFirstListItem(
-      `user_id="${userId}" && week_number=${weekNumber}`
-    );
-    return pb.collection('quiz_cache').update(r.id, { questions: quiz.questions, meta: quiz.meta });
-  } catch {
-    return pb.collection('quiz_cache').create({
-      user_id: userId, week_number: weekNumber, questions: quiz.questions, meta: quiz.meta,
-    });
-  }
+export function setCachedQuiz(userId, weekNumber, quiz) {
+  const data = { questions: quiz.questions, meta: quiz.meta };
+  return pbUpsert('quiz_cache', `user_id="${userId}" && week_number=${weekNumber}`,
+    data, { user_id: userId, week_number: weekNumber, ...data });
 }
 
 // ── Learn Progress ────────────────────────────────────────────────────────────
@@ -210,15 +203,9 @@ export async function getLearnDone(userId, weekNumber) {
   } catch { return false; }
 }
 
-export async function setLearnDone(userId, weekNumber) {
-  try {
-    const r = await pb.collection('learn_progress').getFirstListItem(
-      `user_id="${userId}" && week_number=${weekNumber}`
-    );
-    return pb.collection('learn_progress').update(r.id, { done: true });
-  } catch {
-    return pb.collection('learn_progress').create({ user_id: userId, week_number: weekNumber, done: true });
-  }
+export function setLearnDone(userId, weekNumber) {
+  return pbUpsert('learn_progress', `user_id="${userId}" && week_number=${weekNumber}`,
+    { done: true }, { user_id: userId, week_number: weekNumber, done: true });
 }
 
 // ── Leaderboard ───────────────────────────────────────────────────────────────
@@ -255,13 +242,8 @@ export async function getSetting(key, defaultValue = null) {
   } catch { return defaultValue; }
 }
 
-export async function setSetting(key, value) {
-  try {
-    const r = await pb.collection('settings').getFirstListItem(`key="${key}"`);
-    return pb.collection('settings').update(r.id, { value: String(value) });
-  } catch {
-    return pb.collection('settings').create({ key, value: String(value) });
-  }
+export function setSetting(key, value) {
+  return pbUpsert('settings', `key="${key}"`, { value: String(value) }, { key, value: String(value) });
 }
 
 // ── Curriculum ────────────────────────────────────────────────────────────────
@@ -283,19 +265,9 @@ export async function getCurriculumWeek(year, weekNumber) {
   } catch { return null; }
 }
 
-export async function setCurriculumWeek(year, weekNumber, data) {
-  try {
-    const r = await pb.collection('curriculum').getFirstListItem(
-      `year=${year} && week_number=${weekNumber}`
-    );
-    return pb.collection('curriculum').update(r.id, data);
-  } catch {
-    return pb.collection('curriculum').create({
-      year,
-      week_number: weekNumber,
-      ...data,
-    });
-  }
+export function setCurriculumWeek(year, weekNumber, data) {
+  return pbUpsert('curriculum', `year=${year} && week_number=${weekNumber}`,
+    data, { year, week_number: weekNumber, ...data });
 }
 
 export async function deleteCurriculumWeek(year, weekNumber) {
diff --git a/src/lib/extractionPipeline.js b/src/lib/extractionPipeline.js
index 38afae1..499f65e 100644
--- a/src/lib/extractionPipeline.js
+++ b/src/lib/extractionPipeline.js
@@ -1,5 +1,5 @@
 import * as db from './db';
-import { callLLM } from './llm';
+import { callLLM, cachedSystem } from './llm';
 import { extractionLimiter } from './llmRetry';
 import { EMIT_KNOWLEDGE_GRAPH_TOOL } from './llmTools';
 
@@ -42,8 +42,6 @@ Assign a learning_relevance to every topic:
 Relation types: related_to | depends_on | part_of | executed_by.
 `;
 
-const cachedSystem = (text) => [{ type: 'text', text, cache_control: { type: 'ephemeral' } }];
-
 /**
  * Sentence-aware chunker with overlap.
  *
@@ -171,7 +169,7 @@ export async function processSourceText(textContent, sourceName, { signal } = {}
       }
     }
 
-    await mergeKnowledgeGraph({ topics: allExtractedTopics, relations: allExtractedRelations });
+    await mergeKnowledgeGraph(existingTopics, { topics: allExtractedTopics, relations: allExtractedRelations });
     await db.updateSourceStatus(sourceId, 'completed');
 
     return { success: true, data: { topics: allExtractedTopics, relations: allExtractedRelations } };
@@ -183,8 +181,7 @@ export async function processSourceText(textContent, sourceName, { signal } = {}
   }
 }
 
-async function mergeKnowledgeGraph(newData) {
-  const existingTopics = await db.getTopics();
+async function mergeKnowledgeGraph(existingTopics, newData) {
   const existingRelations = await db.getRelations();
 
   const topicsMap = new Map(existingTopics.map(t => [t.id, t]));
diff --git a/src/lib/learningService.js b/src/lib/learningService.js
index f47ac1c..7415b9a 100644
--- a/src/lib/learningService.js
+++ b/src/lib/learningService.js
@@ -1,5 +1,5 @@
 import * as db from './db';
-import { callLLM } from './llm';
+import { callLLM, cachedSystem } from './llm';
 import {
   EMIT_LEARNING_ARTICLE_TOOL,
   EMIT_LEARNING_SLIDES_TOOL,
@@ -17,8 +17,6 @@ Always write in clear, professional English.
 
 Emit the requested content through the matching tool — do not return prose JSON.`;
 
-const cachedSystem = (text) => [{ type: 'text', text, cache_control: { type: 'ephemeral' } }];
-
 const TOOL_BY_TYPE = {
   article: EMIT_LEARNING_ARTICLE_TOOL,
   slides: EMIT_LEARNING_SLIDES_TOOL,
diff --git a/src/lib/llm.js b/src/lib/llm.js
index 5ae41a0..b230e09 100644
--- a/src/lib/llm.js
+++ b/src/lib/llm.js
@@ -106,6 +106,8 @@ export function parseStructuredText(raw) {
   throw new LLMOutputError('No balanced JSON value found in LLM output.');
 }
 
+export const cachedSystem = (text) => [{ type: 'text', text, cache_control: { type: 'ephemeral' } }];
+
 function buildMessages({ messages, user }) {
   if (Array.isArray(messages) && messages.length) return messages;
   if (typeof user === 'string' && user.length) return [{ role: 'user', content: user }];
@@ -175,7 +177,7 @@ const SIMULATION_INFOGRAPHIC = {
 
 const SIMULATION_TOOL_STUBS = {
   emit_knowledge_graph: SIMULATION_EXTRACTION_GRAPH,
-  emit_handbook_delta: SIMULATION_EXTRACTION_GRAPH,
+
   emit_learning_article: { article: SIMULATION_ARTICLE },
   emit_learning_slides: { slides: [SIMULATION_SLIDE] },
   emit_learning_infographic: { infographic: SIMULATION_INFOGRAPHIC },
diff --git a/src/lib/storage.js b/src/lib/storage.js
index 066ba95..d3671d0 100644
--- a/src/lib/storage.js
+++ b/src/lib/storage.js
@@ -33,7 +33,6 @@ export const storage = {
     } catch (e) {
       if (e.name === 'QuotaExceededError' || e.code === 22) {
         console.error(`Storage quota exceeded when setting ${key}.`);
-        // We could implement a strategy here to clear old cached kb:tests
       } else {
         console.error(`Error saving ${key} to storage:`, e);
       }
diff --git a/src/lib/testService.js b/src/lib/testService.js
index 6391af3..7d3e4b2 100644
--- a/src/lib/testService.js
+++ b/src/lib/testService.js
@@ -1,5 +1,5 @@
 import * as db from './db';
-import { callLLM } from './llm';
+import { callLLM, cachedSystem } from './llm';
 import { EMIT_QUIZ_QUESTIONS_TOOL } from './llmTools';
 import { getCurriculumTopic, getQuarterForWeek } from './curriculumService';
 import { shuffle, sample } from './random';
@@ -25,8 +25,6 @@ const BANNED_OPTION_PATTERNS = [
   /both a and d/i,
 ];
 
-const cachedSystem = (text) => [{ type: 'text', text, cache_control: { type: 'ephemeral' } }];
-
 function normalizeQuestionText(text) {
   return String(text || '')
     .toLowerCase()