diff --git a/main.html b/main.html
index d5d572b..cf9febb 100644
--- a/main.html
+++ b/main.html
@@ -12,6 +12,7 @@
     <script defer src="src/ai.js"></script>
     <script defer src="src/save-utils.js"></script>
     <script defer src="src/app.js"></script>
+    <script defer src="src/compendium.js"></script>
     <!-- Local vendor Alpine (use a real alpine.min.js here for offline runs) -->
     <script defer src="src/vendor/alpine.min.js"></script>
 
diff --git a/src/app.js b/src/app.js
index c79c4c9..29fd6c6 100644
--- a/src/app.js
+++ b/src/app.js
@@ -133,6 +133,13 @@ db.version(3).stores({
     // noop migration for now; existing installs will get empty prompts/codex
 });
 
+// Add compendium table (v4)
+db.version(4).stores({
+    compendium: 'id, projectId, category, title, modified, tags'
+}).upgrade(async tx => {
+    // noop migration; new installs will get empty compendium
+});
+
 // Alpine.js App
 document.addEventListener('alpine:init', () => {
     Alpine.data('app', () => ({
diff --git a/src/compendium.js b/src/compendium.js
new file mode 100644
index 0000000..bece283
--- /dev/null
+++ b/src/compendium.js
@@ -0,0 +1,90 @@
+// Simple Compendium module backed by Dexie `db` defined in app.js
+(function () {
+    try {
+        const Compendium = {
+            async createEntry(projectId, { category = 'lore', title = '', body = '', tags = [] } = {}) {
+                const id = Date.now().toString() + '-' + Math.random().toString(36).slice(2, 8);
+                const now = new Date();
+                const entry = { id, projectId, category, title, body, summary: '', tags: (tags || []).slice(0, 10), created: now, modified: now, order: 0 };
+                await db.compendium.add(entry);
+                return entry;
+            },
+
+            async updateEntry(id, updates) {
+                updates.modified = new Date();
+                await db.compendium.update(id, updates);
+                return db.compendium.get(id);
+            },
+
+            async deleteEntry(id) {
+                await db.compendium.delete(id);
+            },
+
+            async getEntry(id) {
+                return db.compendium.get(id);
+            },
+
+            async listByCategory(projectId, category) {
+                return db.compendium.where({ projectId, category }).sortBy('order');
+            },
+
+            async search(projectId, q, options = {}) {
+                q = (q || '').trim().toLowerCase();
+                const limit = options.limit || 20;
+                if (!q) {
+                    return (await db.compendium.where('projectId').equals(projectId).limit(limit).toArray()) || [];
+                }
+                const all = await db.compendium.where('projectId').equals(projectId).toArray();
+                const results = all.filter(e => {
+                    const hay = ((e.title || '') + '\n' + (e.tags || []).join(' ') + '\n' + (e.body || '')).toLowerCase();
+                    return hay.indexOf(q) !== -1;
+                }).slice(0, limit);
+                return results;
+            },
+
+            async summaries(projectId, ids = []) {
+                const out = {};
+                for (const id of ids) {
+                    const e = await db.compendium.get(id);
+                    if (!e) continue;
+                    if (e.summary && e.summary.length > 10) out[id] = e.summary;
+                    else out[id] = (e.body || '').slice(0, 300) + ((e.body || '').length > 300 ? '…' : '');
+                }
+                return out;
+            },
+
+            async export(projectId) {
+                return db.compendium.where('projectId').equals(projectId).toArray();
+            },
+
+            async import(projectId, items = [], opts = { merge: true }) {
+                const added = [];
+                for (const it of items) {
+                    const entry = Object.assign({}, it);
+                    entry.projectId = projectId;
+                    entry.id = entry.id || (Date.now().toString() + '-' + Math.random().toString(36).slice(2, 6));
+                    entry.created = entry.created ? new Date(entry.created) : new Date();
+                    entry.modified = new Date();
+                    await db.compendium.put(entry);
+                    added.push(entry);
+                }
+                return added;
+            }
+        };
+
+        window.Compendium = Compendium;
+
+        // Test helper
+        window.__test = window.__test || {};
+        window.__test.seedCompendium = async function (projectId, entries) {
+            const created = [];
+            for (const e of (entries || [])) {
+                const en = await Compendium.createEntry(projectId, e);
+                created.push(en);
+            }
+            return created;
+        };
+    } catch (e) {
+        console.warn('Failed to attach Compendium module:', e && e.message ? e.message : e);
+    }
+})();
diff --git a/tests/unit-compendium.js b/tests/unit-compendium.js
new file mode 100644
index 0000000..d87cf11
--- /dev/null
+++ b/tests/unit-compendium.js
@@ -0,0 +1,64 @@
+const { chromium } = require('playwright');
+const path = require('path');
+
+(async () => {
+    const projectRoot = path.resolve(__dirname, '..');
+    const fileUrl = process.env.APP_URL || ('file:///' + path.join(projectRoot, 'main.html').replace(/\\/g, '/'));
+
+    console.log('Opening:', fileUrl);
+    const browser = await chromium.launch({ headless: true });
+    const context = await browser.newContext();
+    const page = await context.newPage();
+
+    page.on('console', msg => { try { console.log(`PAGE LOG [${msg.type()}] ${msg.text()}`); } catch (e) { } });
+    page.on('pageerror', err => { console.error('PAGE ERROR', err && err.message ? err.message : err); });
+
+    try {
+        await page.goto(fileUrl, { waitUntil: 'load', timeout: 15000 });
+        await page.waitForSelector('.app-container, .welcome-screen', { timeout: 10000 });
+
+        // Seed project
+        const proj = await page.evaluate(async () => await window.__test.seedProject('CompTest'));
+
+        // Seed compendium entries via API
+        const entries = await page.evaluate(async (pid) => {
+            return await window.__test.seedCompendium(pid, [
+                { category: 'character', title: 'Alice', body: 'Alice is a cautious detective.' },
+                { category: 'location', title: 'Old Harbor', body: 'The Old Harbor smells of salt and diesel.' }
+            ]);
+        }, proj.id);
+
+        if (!Array.isArray(entries) || entries.length < 2) {
+            console.error('Compendium seed failed:', entries);
+            await browser.close();
+            process.exit(2);
+        }
+
+        // Test search
+        const search = await page.evaluate(async (pid) => {
+            return await window.Compendium.search(pid, 'Alice');
+        }, proj.id);
+
+        if (!(Array.isArray(search) && search.length >= 1 && search[0].title === 'Alice')) {
+            console.error('Compendium search failed:', search);
+            await browser.close();
+            process.exit(3);
+        }
+
+        // Test getEntry
+        const fetched = await page.evaluate(async (id) => await window.Compendium.getEntry(id), entries[0].id);
+        if (!fetched || fetched.title !== 'Alice') {
+            console.error('Compendium getEntry failed:', fetched);
+            await browser.close();
+            process.exit(4);
+        }
+
+        console.log('unit-compendium test passed.');
+        await browser.close();
+        process.exit(0);
+    } catch (err) {
+        console.error('unit-compendium test failed:', err && err.message ? err.message : err);
+        await browser.close();
+        process.exit(1);
+    }
+})();