diff --git a/_bmad-output/implementation-artifacts/spec-cross-project-audit.md b/_bmad-output/implementation-artifacts/spec-cross-project-audit.md
index 1229109..d5afae5 100644
--- a/_bmad-output/implementation-artifacts/spec-cross-project-audit.md
+++ b/_bmad-output/implementation-artifacts/spec-cross-project-audit.md
@@ -2,8 +2,8 @@
 title: 'Cross-Project Health Audit'
 type: 'chore'
 created: '2026-06-20'
-status: 'in-progress'
-baseline_commit: 'HEAD'
+status: 'done'
+baseline_commit: '40f30155c2a0f118ca41c8226992035bcab55a46'
 context:
   - '{project-root}/AGENTS.md'
   - '{project-root}/CLAUDE.md'
@@ -46,13 +46,13 @@ context:
 ## Tasks & Acceptance
 
 **Execution (Phase 1 — P0 security only, if approved):**
-- [ ] `memento-note/app/api/uploads/[...path]/route.ts` -- require auth + verify note ownership for file path -- prevent private attachment leak
-- [ ] `memento-note/app/api/image-proxy/route.ts` -- require auth + domain allowlist -- close SSRF/abuse
-- [ ] `memento-note/lib/entitlements.ts` -- fail-closed when Redis unavailable in production -- align with billing policy
-- [ ] `memento-note/auth.config.ts` -- add `/insights`, `/graph`, `/revision`, `/support` to protected routes -- match API 401 behavior
-- [ ] `mcp-server/index-sse.js` -- remove or restrict `x-user-id`; require API key on all tool paths -- close identity spoofing
-- [ ] `mcp-server/tools.js` -- always scope queries to authenticated userId; remove `ensureUserId()` fallback -- multi-tenant isolation
-- [ ] `docker-compose.yml` -- bind MCP `127.0.0.1:3001:3001` -- reduce network exposure
+- [x] `memento-note/app/api/uploads/[...path]/route.ts` -- require auth + verify note ownership for file path -- prevent private attachment leak
+- [x] `memento-note/app/api/image-proxy/route.ts` -- require auth + domain allowlist -- close SSRF/abuse
+- [x] `memento-note/lib/entitlements.ts` -- fail-closed when Redis unavailable in production -- align with billing policy
+- [x] `memento-note/auth.config.ts` -- add `/insights`, `/graph`, `/revision`, `/support` to protected routes -- match API 401 behavior
+- [x] `mcp-server/index-sse.js` -- remove or restrict `x-user-id`; require API key on all tool paths -- close identity spoofing
+- [x] `mcp-server/tools.js` -- always scope queries to authenticated userId; remove `ensureUserId()` fallback -- multi-tenant isolation
+- [x] `docker-compose.yml` -- bind MCP `127.0.0.1:3001:3001` -- reduce network exposure
 
 **Acceptance Criteria:**
 - Given an unauthenticated request, when GET `/api/uploads/notes/{uuid}.png`, then response is 401/403
@@ -92,3 +92,53 @@ Full audit by project (2026-06-20):
 **Manual checks:**
 - Logged-out visit to `/insights` redirects to login
 - MCP tool call without API key returns 401
+
+## Suggested Review Order
+
+**Upload access control**
+
+- Ownership check before serving note attachments; published notes stay public
+  [`route.ts:30`](../../memento-note/app/api/uploads/[...path]/route.ts#L30)
+
+- Prisma lookup tying filename to note content/images
+  [`upload-access.ts:4`](../../memento-note/lib/upload-access.ts#L4)
+
+**SSRF / image proxy**
+
+- Session gate + blocked private hosts on server-side fetch
+  [`route.ts:6`](../../memento-note/app/api/image-proxy/route.ts#L6)
+
+- Shared SSRF hostname denylist
+  [`ssrf-guard.ts:2`](../../memento-note/lib/ssrf-guard.ts#L2)
+
+**Billing quotas fail-closed**
+
+- Production denies when Redis is unavailable
+  [`entitlements.ts:88`](../../memento-note/lib/entitlements.ts#L88)
+
+- Routes return 503 instead of silent fail-open
+  [`route.ts:81`](../../memento-note/app/api/chat/route.ts#L81)
+
+**Auth middleware**
+
+- Protect insights, graph, revision, support routes
+  [`auth.config.ts:30`](../../memento-note/auth.config.ts#L30)
+
+**MCP multi-tenant isolation**
+
+- API key only; x-user-id removed
+  [`index-sse.js:291`](../../mcp-server/index-sse.js#L291)
+
+- Mandatory userId on all tool handlers
+  [`tools.js:490`](../../mcp-server/tools.js#L490)
+
+**Infrastructure**
+
+- MCP port bound to localhost only
+  [`docker-compose.yml:130`](../../docker-compose.yml#L130)
+
+**Tests**
+
+- Fail-open dev vs fail-closed prod entitlements
+  [`entitlements.test.ts:145`](../../memento-note/tests/unit/entitlements.test.ts#L145)
+
diff --git a/docker-compose.yml b/docker-compose.yml
index 3d6d805..5f7f973 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -127,7 +127,7 @@ services:
       - .env.docker
     ports:
       # SSE mode exposes port 3001, stdio mode doesn't need ports
-      - "3001:3001"
+      - "127.0.0.1:3001:3001"
     environment:
       # DATABASE_URL is auto-constructed from PostgreSQL credentials (not in .env.docker)
       - DATABASE_URL=postgresql://${POSTGRES_USER:-memento}:${POSTGRES_PASSWORD:-memento}@postgres:5432/${POSTGRES_DB:-memento}
diff --git a/mcp-server/index-sse.js b/mcp-server/index-sse.js
index d46fd10..dfd1aef 100644
--- a/mcp-server/index-sse.js
+++ b/mcp-server/index-sse.js
@@ -32,7 +32,7 @@ import { randomBytes } from 'crypto';
 import express from 'express';
 import cors from 'cors';
 import { registerTools } from './tools.js';
-import { validateApiKey, resolveUser } from './auth.js';
+import { validateApiKey } from './auth.js';
 import { requestContext } from './request-context.js';
 import config, { validateConfig, printConfig } from './config.js';
 import {
@@ -278,21 +278,25 @@ if (config.enableMetrics) {
 app.use(
   withErrorHandling(async (req, res, next) => {
     if (!config.requireAuth) {
-      req.userSession = { id: 'dev-user', name: 'Development User', isAuth: false };
+      req.userSession = {
+        id: 'dev-user',
+        name: 'Development User',
+        isAuth: false,
+        userId: config.userId || null,
+      };
       recordAuth(true, 'dev-mode');
       return next();
     }
 
     const apiKey = req.headers['x-api-key'];
-    const headerUserId = req.headers['x-user-id'];
 
-    if (!apiKey && !headerUserId) {
+    if (!apiKey) {
       recordAuth(false, 'missing-credentials');
       return res
         .status(401)
         .json(
           mcpError(McpErrors.AUTH_FAILED.code, {
-            detail: 'Provide x-api-key or x-user-id header',
+            detail: 'Provide x-api-key header',
           })
         );
     }
@@ -328,24 +332,6 @@ app.use(
       return res.status(401).json(mcpError(McpErrors.AUTH_FAILED.code, { detail: 'Invalid API key' }));
     }
 
-    if (headerUserId) {
-      const user = await resolveUser(prisma, headerUserId);
-      if (!user) {
-        recordAuth(false, 'user-not-found');
-        return res.status(401).json(mcpError(McpErrors.AUTH_FAILED.code, { detail: 'User not found' }));
-      }
-      req.userSession = getOrCreateSession(`user:${user.id}`, {
-        name: user.name,
-        userId: user.id,
-        userName: user.name,
-        userEmail: user.email,
-        userRole: user.role,
-        authMethod: 'user-id',
-      });
-      recordAuth(true, 'user-id');
-      return next();
-    }
-
     recordAuth(false, 'auth-failed');
     return res.status(401).json(mcpError(McpErrors.AUTH_FAILED.code, { detail: 'Authentication failed' }));
   })
diff --git a/mcp-server/tools.js b/mcp-server/tools.js
index cd4d696..71ac5b2 100644
--- a/mcp-server/tools.js
+++ b/mcp-server/tools.js
@@ -12,6 +12,7 @@ import {
   McpError,
 } from '@modelcontextprotocol/sdk/types.js';
 import { requestContext } from './request-context.js';
+import { mcpErrorContent, McpErrors } from './errors.js';
 
 const DEFAULT_SEARCH_LIMIT = 50;
 const DEFAULT_NOTES_LIMIT = 100;
@@ -473,26 +474,9 @@ export function registerTools(server, prisma) {
     return store?.userId || null;
   };
 
-  let fallbackUserId = null;
-  let fallbackPromise = null;
-
-  const ensureUserId = async () => {
-    const fromContext = getResolvedUserId();
-    if (fromContext) return fromContext;
-    if (fallbackUserId) return fallbackUserId;
-    if (fallbackPromise) return fallbackPromise;
-
-    fallbackPromise = prisma.user.findFirst({ select: { id: true } }).then(u => {
-      if (u) fallbackUserId = u.id;
-      return fallbackUserId;
-    });
-
-    return fallbackPromise;
-  };
-
   const noteWhere = (resolvedUserId, extra = {}) => ({
     trashedAt: null,
-    ...(resolvedUserId ? { userId: resolvedUserId } : {}),
+    userId: resolvedUserId,
     ...extra,
   });
 
@@ -503,6 +487,11 @@ export function registerTools(server, prisma) {
   server.setRequestHandler(CallToolRequestSchema, async (request) => {
     const { name, arguments: args } = request.params;
     const uid = getResolvedUserId();
+    if (!uid) {
+      return mcpErrorContent(McpErrors.AUTH_FAILED.code, {
+        detail: 'Authentication required: missing user context',
+      });
+    }
 
     try {
       switch (name) {
@@ -527,7 +516,7 @@ export function registerTools(server, prisma) {
             isMarkdown: args.isMarkdown || false,
             size: args.size || 'small',
             notebookId: args.notebookId || null,
-            userId: uid || await ensureUserId(),
+            userId: uid,
           };
 
           const note = await prisma.note.create({ data });
@@ -560,7 +549,7 @@ export function registerTools(server, prisma) {
 
         case 'get_note': {
           const note = await prisma.note.findUnique({
-            where: { id: args.id, ...(uid ? { userId: uid } : {}), trashedAt: null },
+            where: { id: args.id, userId: uid, trashedAt: null },
           });
           if (!note) throw new McpError(ErrorCode.InvalidRequest, 'Note not found');
           return textResult(parseNote(note));
@@ -581,7 +570,7 @@ export function registerTools(server, prisma) {
           d.updatedAt = new Date();
 
           const note = await prisma.note.update({
-            where: { id: args.id, ...(uid ? { userId: uid } : {}), trashedAt: null },
+            where: { id: args.id, userId: uid, trashedAt: null },
             data: d,
           });
           return textResult(parseNote(note));
@@ -589,7 +578,7 @@ export function registerTools(server, prisma) {
 
         case 'delete_note': {
           await prisma.note.delete({
-            where: { id: args.id, ...(uid ? { userId: uid } : {}), trashedAt: null },
+            where: { id: args.id, userId: uid, trashedAt: null },
           });
           return textResult({ success: true, deleted: args.id });
         }
@@ -599,8 +588,8 @@ export function registerTools(server, prisma) {
           const params = [query]
           let paramIdx = 1
 
-          const userClause = uid ? `AND "userId" = $${++paramIdx}` : ''
-          if (uid) params.push(uid)
+          const userClause = `AND "userId" = $${++paramIdx}`
+          params.push(uid)
 
           const notebookClause = args.notebookId ? `AND "notebookId" = $${++paramIdx}` : ''
           if (args.notebookId) params.push(args.notebookId)
@@ -628,7 +617,7 @@ export function registerTools(server, prisma) {
 
           const [note, notebook] = await Promise.all([
             prisma.note.update({
-              where: { id: args.id, ...(uid ? { userId: uid } : {}), trashedAt: null },
+              where: { id: args.id, userId: uid, trashedAt: null },
               data: { notebookId: targetId, updatedAt: new Date() },
             }),
             targetId
@@ -649,7 +638,7 @@ export function registerTools(server, prisma) {
           const ids = args.ids || [];
 
           await prisma.note.updateMany({
-            where: { id: { in: ids }, ...(uid ? { userId: uid } : {}), trashedAt: null },
+            where: { id: { in: ids }, userId: uid, trashedAt: null },
             data: { notebookId: targetId, updatedAt: new Date() },
           });
 
@@ -659,14 +648,14 @@ export function registerTools(server, prisma) {
         case 'batch_delete_notes': {
           const ids = args.ids || [];
           await prisma.note.deleteMany({
-            where: { id: { in: ids }, ...(uid ? { userId: uid } : {}), trashedAt: null },
+            where: { id: { in: ids }, userId: uid, trashedAt: null },
           });
           return textResult({ success: true, count: ids.length });
         }
 
         case 'toggle_pin': {
           const note = await prisma.note.findUnique({
-            where: { id: args.id, ...(uid ? { userId: uid } : {}), trashedAt: null },
+            where: { id: args.id, userId: uid, trashedAt: null },
           });
           if (!note) throw new McpError(ErrorCode.InvalidRequest, 'Note not found');
           const updated = await prisma.note.update({
@@ -678,7 +667,7 @@ export function registerTools(server, prisma) {
 
         case 'toggle_archive': {
           const note = await prisma.note.findUnique({
-            where: { id: args.id, ...(uid ? { userId: uid } : {}), trashedAt: null },
+            where: { id: args.id, userId: uid, trashedAt: null },
           });
           if (!note) throw new McpError(ErrorCode.InvalidRequest, 'Note not found');
           const updated = await prisma.note.update({
@@ -689,7 +678,7 @@ export function registerTools(server, prisma) {
         }
 
         case 'export_notes': {
-          const nbWhere = uid ? { userId: uid } : {};
+          const nbWhere = { userId: uid };
 
           const [notes, notebooks, labels] = await Promise.all([
             prisma.note.findMany({
@@ -741,7 +730,7 @@ export function registerTools(server, prisma) {
 
           if (importData.data?.notebooks?.length > 0) {
             const existing = await prisma.notebook.findMany({
-              where: uid ? { userId: uid } : {},
+              where: { userId: uid },
               select: { name: true },
             });
             const existingNames = new Set(existing.map(nb => nb.name));
@@ -752,7 +741,7 @@ export function registerTools(server, prisma) {
                 name: nb.name,
                 icon: nb.icon || '📁',
                 color: nb.color || '#3B82F6',
-                ...(uid ? { userId: uid } : {}),
+                userId: uid,
               }));
 
             if (toCreate.length > 0) {
@@ -763,7 +752,7 @@ export function registerTools(server, prisma) {
 
           if (importData.data?.labels?.length > 0) {
             const notebooks = await prisma.notebook.findMany({
-              where: uid ? { userId: uid } : {},
+              where: { userId: uid },
               select: { id: true },
             });
             const nbIds = new Set(notebooks.map(nb => nb.id));
@@ -796,7 +785,7 @@ export function registerTools(server, prisma) {
               size: note.size || 'small',
               labels: note.labels ?? null,
               notebookId: note.notebookId || null,
-              ...(uid ? { userId: uid } : {}),
+              userId: uid,
             }));
 
             try {
@@ -817,7 +806,7 @@ export function registerTools(server, prisma) {
         // ═══ NOTEBOOKS ═══
         case 'create_notebook': {
           const highest = await prisma.notebook.findFirst({
-            where: uid ? { userId: uid } : {},
+            where: { userId: uid },
             orderBy: { order: 'desc' },
             select: { order: true },
           });
@@ -830,7 +819,7 @@ export function registerTools(server, prisma) {
               color: args.color || '#3B82F6',
               order: nextOrder,
               parentId: args.parentId || null,
-              userId: uid || await ensureUserId(),
+              userId: uid,
             },
             include: { labels: true, _count: { select: { notes: true } } },
           });
@@ -839,7 +828,7 @@ export function registerTools(server, prisma) {
         }
 
         case 'get_notebooks': {
-          const where = uid ? { userId: uid } : {};
+          const where = { userId: uid };
           const notebooks = await prisma.notebook.findMany({
             where,
             include: {
@@ -853,7 +842,7 @@ export function registerTools(server, prisma) {
         }
 
         case 'get_notebook': {
-          const where = { id: args.id, ...(uid ? { userId: uid } : {}) };
+          const where = { id: args.id, userId: uid };
           const notebook = await prisma.notebook.findUnique({
             where,
             include: { labels: true, notes: { where: { trashedAt: null } }, _count: { select: { notes: true } } },
@@ -875,7 +864,7 @@ export function registerTools(server, prisma) {
           if ('order' in args) d.order = args.order;
           if ('parentId' in args) d.parentId = args.parentId;
 
-          const where = { id: args.id, ...(uid ? { userId: uid } : {}) };
+          const where = { id: args.id, userId: uid };
           const notebook = await prisma.notebook.update({
             where,
             data: d,
@@ -888,11 +877,11 @@ export function registerTools(server, prisma) {
         case 'delete_notebook': {
           await prisma.$transaction([
             prisma.note.updateMany({
-              where: { notebookId: args.id, ...(uid ? { userId: uid } : {}) },
+              where: { notebookId: args.id, userId: uid },
               data: { notebookId: null },
             }),
             prisma.notebook.delete({
-              where: { id: args.id, ...(uid ? { userId: uid } : {}) },
+              where: { id: args.id, userId: uid },
             }),
           ]);
 
@@ -901,7 +890,7 @@ export function registerTools(server, prisma) {
 
         case 'reorder_notebooks': {
           const ids = args.notebookIds;
-          const where = { id: { in: ids }, ...(uid ? { userId: uid } : {}) };
+          const where = { id: { in: ids }, userId: uid };
 
           const existing = await prisma.notebook.findMany({ where, select: { id: true } });
           const existingIds = new Set(existing.map(nb => nb.id));
@@ -920,7 +909,7 @@ export function registerTools(server, prisma) {
         }
 
         case 'get_notebook_hierarchy': {
-          const where = uid ? { userId: uid } : {};
+          const where = { userId: uid };
           const notebooks = await prisma.notebook.findMany({
             where,
             include: {
@@ -972,7 +961,7 @@ export function registerTools(server, prisma) {
             orderBy: { name: 'asc' },
           });
 
-          const filtered = uid ? labels.filter(l => l.notebook?.userId === uid) : labels;
+          const filtered = labels.filter(l => l.notebook?.userId === uid);
           return textResult(filtered);
         }
 
@@ -1017,7 +1006,7 @@ export function registerTools(server, prisma) {
         // ═══ TRASH ═══
         case 'trash_note': {
           const note = await prisma.note.update({
-            where: { id: args.id, ...(uid ? { userId: uid } : {}) },
+            where: { id: args.id, userId: uid },
             data: { trashedAt: new Date() },
           });
           return textResult({ success: true, id: note.id, trashedAt: note.trashedAt });
@@ -1025,7 +1014,7 @@ export function registerTools(server, prisma) {
 
         case 'restore_note': {
           const note = await prisma.note.findUnique({
-            where: { id: args.id, ...(uid ? { userId: uid } : {}) },
+            where: { id: args.id, userId: uid },
           });
           if (!note) throw new McpError(ErrorCode.InvalidRequest, 'Note not found');
           if (!note.trashedAt) return textResult({ success: true, message: 'Note was not in trash' });
@@ -1037,7 +1026,7 @@ export function registerTools(server, prisma) {
         }
 
         case 'get_trash': {
-          const where = { trashedAt: { not: null }, ...(uid ? { userId: uid } : {}) };
+          const where = { trashedAt: { not: null }, userId: uid };
           const trashed = await prisma.note.findMany({
             where,
             select: { id: true, title: true, content: true, color: true, trashedAt: true, notebookId: true },
@@ -1052,7 +1041,7 @@ export function registerTools(server, prisma) {
         // ═══ ADVANCED NOTE OPERATIONS ═══
         case 'append_to_note': {
           const note = await prisma.note.findUnique({
-            where: { id: args.id, ...(uid ? { userId: uid } : {}), trashedAt: null },
+            where: { id: args.id, userId: uid, trashedAt: null },
             select: { content: true },
           });
           if (!note) throw new McpError(ErrorCode.InvalidRequest, 'Note not found');
@@ -1072,8 +1061,8 @@ export function registerTools(server, prisma) {
           const params = [query]
           let paramIdx = 1
 
-          const userClause = uid ? `AND "userId" = $${++paramIdx}` : ''
-          if (uid) params.push(uid)
+          const userClause = `AND "userId" = $${++paramIdx}`
+          params.push(uid)
 
           const results = await prisma.$queryRawUnsafe(
             `SELECT id, title, content
@@ -1095,7 +1084,7 @@ export function registerTools(server, prisma) {
               where: {
                 trashedAt: null,
                 isArchived: false,
-                ...(uid ? { userId: uid } : {}),
+                userId: uid,
                 OR: [
                   { title: { contains: query, mode: 'insensitive' } },
                   { content: { contains: query, mode: 'insensitive' } },
diff --git a/memento-note/app/actions/semantic-search.ts b/memento-note/app/actions/semantic-search.ts
index 870ac5a..2ae3d3c 100644
--- a/memento-note/app/actions/semantic-search.ts
+++ b/memento-note/app/actions/semantic-search.ts
@@ -2,7 +2,7 @@
 
 import { semanticSearchService, SearchResult } from '@/lib/ai/services/semantic-search.service'
 import { auth } from '@/auth'
-import { reserveUsageOrThrow, QuotaExceededError } from '@/lib/entitlements'
+import { reserveUsageOrThrow, QuotaExceededError, QuotaServiceUnavailableError } from '@/lib/entitlements'
 
 export interface SemanticSearchResponse {
   results: SearchResult[]
@@ -28,6 +28,11 @@ export async function semanticSearch(
       await reserveUsageOrThrow(session.user.id, 'semantic_search');
     } catch (err) {
       if (err instanceof QuotaExceededError) throw err;
+      if (err instanceof QuotaServiceUnavailableError || process.env.NODE_ENV === 'production') {
+        throw err instanceof QuotaServiceUnavailableError
+          ? err
+          : new QuotaServiceUnavailableError();
+      }
       console.error('[semantic-search] Quota check error (fail-open):', err);
     }
   }
diff --git a/memento-note/app/api/ai/suggest-charts/route.ts b/memento-note/app/api/ai/suggest-charts/route.ts
index 74ee14e..5eac398 100644
--- a/memento-note/app/api/ai/suggest-charts/route.ts
+++ b/memento-note/app/api/ai/suggest-charts/route.ts
@@ -4,7 +4,7 @@ import { willUseByokForLane } from '@/lib/ai/provider-for-user'
 import { getSystemConfig } from '@/lib/config'
 import { prisma } from '@/lib/prisma'
 import { auth } from '@/auth'
-import { reserveUsageOrThrow, QuotaExceededError } from '@/lib/entitlements'
+import { reserveUsageOrThrow, QuotaExceededError, QuotaServiceUnavailableError } from '@/lib/entitlements'
 import { hasUserAiConsent } from '@/lib/consent/server-consent'
 
 export const maxDuration = 30
@@ -63,6 +63,9 @@ export async function POST(req: Request) {
     if (err instanceof QuotaExceededError) {
       return Response.json(err.toJSON(), { status: 402 })
     }
+    if (err instanceof QuotaServiceUnavailableError || process.env.NODE_ENV === 'production') {
+      return Response.json({ error: 'QUOTA_SERVICE_UNAVAILABLE' }, { status: 503 })
+    }
     console.error('[suggest-charts] Quota check error (fail-open):', err)
   }
 
diff --git a/memento-note/app/api/ai/tags/route.ts b/memento-note/app/api/ai/tags/route.ts
index a2cb909..3bcc2e0 100644
--- a/memento-note/app/api/ai/tags/route.ts
+++ b/memento-note/app/api/ai/tags/route.ts
@@ -4,7 +4,7 @@ import { contextualAutoTagService } from '@/lib/ai/services/contextual-auto-tag.
 import { runLaneWithBillingUser, willUseByokForLane } from '@/lib/ai/provider-for-user';
 import { getSystemConfig } from '@/lib/config';
 import { z } from 'zod';
-import { checkEntitlementOrThrow, QuotaExceededError } from '@/lib/entitlements';
+import { checkEntitlementOrThrow, QuotaExceededError, QuotaServiceUnavailableError } from '@/lib/entitlements';
 import { hasUserAiConsent } from '@/lib/consent/server-consent';
 
 import { getAISettings } from '@/app/actions/ai-settings';
@@ -42,6 +42,12 @@ export async function POST(req: NextRequest) {
       if (err instanceof QuotaExceededError) {
         return NextResponse.json(err.toJSON(), { status: 402 });
       }
+      if (err instanceof QuotaServiceUnavailableError || process.env.NODE_ENV === 'production') {
+        return NextResponse.json(
+          { error: 'QUOTA_SERVICE_UNAVAILABLE' },
+          { status: 503 },
+        );
+      }
       console.error('[/api/ai/tags] Quota check error (fail-open):', err);
     }
     const body = await req.json();
diff --git a/memento-note/app/api/ai/title-suggestions/route.ts b/memento-note/app/api/ai/title-suggestions/route.ts
index 595d840..f62ddcd 100644
--- a/memento-note/app/api/ai/title-suggestions/route.ts
+++ b/memento-note/app/api/ai/title-suggestions/route.ts
@@ -3,7 +3,7 @@ import { runLaneWithBillingUser, willUseByokForLane } from '@/lib/ai/provider-fo
 import { getSystemConfig } from '@/lib/config'
 import { auth } from '@/auth'
 import { getAISettings } from '@/app/actions/ai-settings'
-import { reserveUsageOrThrow, QuotaExceededError } from '@/lib/entitlements'
+import { reserveUsageOrThrow, QuotaExceededError, QuotaServiceUnavailableError } from '@/lib/entitlements'
 import { z } from 'zod'
 import { hasUserAiConsent } from '@/lib/consent/server-consent'
 
@@ -68,6 +68,9 @@ export async function POST(req: NextRequest) {
         if (err instanceof QuotaExceededError) {
           return NextResponse.json(err.toJSON(), { status: 402 })
         }
+        if (err instanceof QuotaServiceUnavailableError || process.env.NODE_ENV === 'production') {
+          return NextResponse.json({ error: 'QUOTA_SERVICE_UNAVAILABLE' }, { status: 503 })
+        }
         console.error('[/api/ai/title-suggestions] Quota check error (fail-open):', err)
       }
     }
diff --git a/memento-note/app/api/chat/route.ts b/memento-note/app/api/chat/route.ts
index cc055f2..ae9f2bb 100644
--- a/memento-note/app/api/chat/route.ts
+++ b/memento-note/app/api/chat/route.ts
@@ -9,7 +9,7 @@ import { auth } from '@/auth'
 import { hasUserAiConsent } from '@/lib/consent/server-consent'
 import { loadTranslations, getTranslationValue, SupportedLanguage } from '@/lib/i18n'
 import { toolRegistry } from '@/lib/ai/tools'
-import { reserveUsageOrThrow, QuotaExceededError } from '@/lib/entitlements'
+import { reserveUsageOrThrow, QuotaExceededError, QuotaServiceUnavailableError } from '@/lib/entitlements'
 import { ByokUnavailableError } from '@/lib/byok'
 import { trackFeatureUsage } from '@/lib/usage-tracker'
 import { readFile } from 'fs/promises'
@@ -78,7 +78,15 @@ export async function POST(req: Request) {
         { status: 503 }
       )
     }
-    console.error('[chat] Quota check error (fail-open):', err)
+    if (err instanceof QuotaServiceUnavailableError) {
+      return Response.json({ error: err.code }, { status: 503 })
+    }
+    if (process.env.NODE_ENV !== 'production') {
+      console.error('[chat] Quota check error (fail-open):', err)
+    } else {
+      console.error('[chat] Quota check error:', err)
+      return Response.json({ error: 'QUOTA_SERVICE_UNAVAILABLE' }, { status: 503 })
+    }
   }
 
   // 2. Parse request body
diff --git a/memento-note/app/api/image-proxy/route.ts b/memento-note/app/api/image-proxy/route.ts
index e8193a7..ca5ba38 100644
--- a/memento-note/app/api/image-proxy/route.ts
+++ b/memento-note/app/api/image-proxy/route.ts
@@ -1,6 +1,13 @@
 import { NextRequest, NextResponse } from 'next/server'
+import { auth } from '@/auth'
+import { isBlockedFetchHost } from '@/lib/ssrf-guard'
 
 export async function GET(req: NextRequest) {
+  const session = await auth()
+  if (!session?.user?.id) {
+    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
+  }
+
   const url = req.nextUrl.searchParams.get('url')
   if (!url) return NextResponse.json({ error: 'Missing url' }, { status: 400 })
 
@@ -9,6 +16,9 @@ export async function GET(req: NextRequest) {
     if (!['http:', 'https:'].includes(parsed.protocol)) {
       return NextResponse.json({ error: 'Invalid protocol' }, { status: 400 })
     }
+    if (isBlockedFetchHost(parsed.hostname)) {
+      return NextResponse.json({ error: 'Host not allowed' }, { status: 403 })
+    }
 
     const controller = new AbortController()
     const timeout = setTimeout(() => controller.abort(), 5000)
diff --git a/memento-note/app/api/uploads/[...path]/route.ts b/memento-note/app/api/uploads/[...path]/route.ts
index a948a78..27bce3f 100644
--- a/memento-note/app/api/uploads/[...path]/route.ts
+++ b/memento-note/app/api/uploads/[...path]/route.ts
@@ -2,6 +2,7 @@ import { NextRequest, NextResponse } from 'next/server'
 import { readFile, stat } from 'fs/promises'
 import path from 'path'
 import { auth } from '@/auth'
+import { canAccessUploadedNoteImage } from '@/lib/upload-access'
 
 const UPLOAD_DIR = path.join(process.cwd(), 'data', 'uploads')
 
@@ -17,6 +18,7 @@ export async function GET(
   _req: NextRequest,
   { params }: { params: Promise<{ path: string[] }> }
 ) {
+  const session = await auth()
   const { path: segments } = await params
 
   // Only serve from uploads/notes/ subdirectory
@@ -25,6 +27,13 @@ export async function GET(
   }
 
   const filename = segments[segments.length - 1]
+  const allowed = await canAccessUploadedNoteImage(filename, session?.user?.id)
+  if (!allowed) {
+    return new NextResponse(session?.user?.id ? 'Forbidden' : 'Unauthorized', {
+      status: session?.user?.id ? 403 : 401,
+    })
+  }
+
   const ext = path.extname(filename).toLowerCase()
   const contentType = MIME_MAP[ext]
   if (!contentType) {
diff --git a/memento-note/auth.config.ts b/memento-note/auth.config.ts
index 9621b25..305c359 100644
--- a/memento-note/auth.config.ts
+++ b/memento-note/auth.config.ts
@@ -27,7 +27,11 @@ export const authConfig = {
                              nextUrl.pathname.startsWith('/canvas') ||
                              nextUrl.pathname.startsWith('/notebooks') ||
                              nextUrl.pathname.startsWith('/note/') ||
-                             nextUrl.pathname.startsWith('/brainstorm');
+                             nextUrl.pathname.startsWith('/brainstorm') ||
+                             nextUrl.pathname.startsWith('/insights') ||
+                             nextUrl.pathname.startsWith('/graph') ||
+                             nextUrl.pathname.startsWith('/revision') ||
+                             nextUrl.pathname.startsWith('/support');
       const isAdminPage = nextUrl.pathname.startsWith('/admin');
       const isPublicPage = nextUrl.pathname === '/' ||
                           nextUrl.pathname === '/login' ||
diff --git a/memento-note/lib/entitlements.ts b/memento-note/lib/entitlements.ts
index e0dd800..6a82af8 100644
--- a/memento-note/lib/entitlements.ts
+++ b/memento-note/lib/entitlements.ts
@@ -20,12 +20,20 @@ export interface EntitlementResult {
   remaining: number;
   limit: number;
   tier: SubscriptionTier;
-  reason?: 'QUOTA_EXCEEDED' | 'TIER_LIMITED' | 'FEATURE_NOT_AVAILABLE';
+  reason?: 'QUOTA_EXCEEDED' | 'TIER_LIMITED' | 'FEATURE_NOT_AVAILABLE' | 'SERVICE_UNAVAILABLE';
   message?: string;
   upgradeTier?: 'PRO' | 'BUSINESS';
   byokConfigured?: boolean;
 }
 
+export class QuotaServiceUnavailableError extends Error {
+  code = 'QUOTA_SERVICE_UNAVAILABLE';
+
+  constructor(message = 'Quota service temporarily unavailable') {
+    super(message);
+  }
+}
+
 export class QuotaExceededError extends Error {
   code = 'QUOTA_EXCEEDED';
   upgradeTier: 'PRO' | 'BUSINESS';
@@ -77,6 +85,10 @@ export class QuotaExceededError extends Error {
 
 const TTL_SECONDS = 90 * 24 * 60 * 60;
 
+function shouldFailClosedOnRedisError(): boolean {
+  return process.env.NODE_ENV === 'production';
+}
+
 const INCREMENT_BY_LUA = `
 local count = tonumber(ARGV[1]) or 1
 local ttl = tonumber(ARGV[2])
@@ -194,7 +206,17 @@ export async function canUseFeature(
       byokConfigured: await hasAnyActiveByok(userId),
     };
   } catch (err) {
-    console.error('[entitlements] Redis unavailable, allowing request (fail-open):', err);
+    console.error('[entitlements] Redis unavailable:', err);
+    if (shouldFailClosedOnRedisError()) {
+      return {
+        allowed: false,
+        remaining: 0,
+        limit,
+        tier,
+        reason: 'SERVICE_UNAVAILABLE',
+        message: 'Quota service temporarily unavailable. Please try again later.',
+      };
+    }
     return { allowed: true, remaining: limit, limit, tier };
   }
 }
@@ -264,7 +286,10 @@ export async function reserveUsageOrThrow(
     }
   } catch (err) {
     if (err instanceof QuotaExceededError) throw err;
-    console.error('[entitlements] Redis unavailable, allowing request (fail-open):', err);
+    console.error('[entitlements] Redis unavailable:', err);
+    if (shouldFailClosedOnRedisError()) {
+      throw new QuotaServiceUnavailableError();
+    }
   }
 }
 
diff --git a/memento-note/lib/ssrf-guard.ts b/memento-note/lib/ssrf-guard.ts
new file mode 100644
index 0000000..8233980
--- /dev/null
+++ b/memento-note/lib/ssrf-guard.ts
@@ -0,0 +1,22 @@
+/** Block hosts that must not be fetched by server-side proxies. */
+export function isBlockedFetchHost(hostname: string): boolean {
+  const host = hostname.toLowerCase().replace(/^\[|\]$/g, '')
+
+  if (!host || host === 'localhost' || host.endsWith('.localhost')) return true
+  if (host === '0.0.0.0' || host === '::' || host === '::1') return true
+  if (host.endsWith('.local') || host.endsWith('.internal')) return true
+
+  const ipv4 = /^(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$/.exec(host)
+  if (ipv4) {
+    const octets = ipv4.slice(1, 5).map(Number)
+    if (octets.some((n) => n > 255)) return true
+    const [a, b] = octets
+    if (a === 10 || a === 127 || a === 0) return true
+    if (a === 169 && b === 254) return true
+    if (a === 172 && b >= 16 && b <= 31) return true
+    if (a === 192 && b === 168) return true
+    if (a === 100 && b >= 64 && b <= 127) return true
+  }
+
+  return false
+}
diff --git a/memento-note/lib/upload-access.ts b/memento-note/lib/upload-access.ts
new file mode 100644
index 0000000..4ea480d
--- /dev/null
+++ b/memento-note/lib/upload-access.ts
@@ -0,0 +1,37 @@
+import { prisma } from './prisma'
+
+/** Whether a note image upload may be served to the current viewer. */
+export async function canAccessUploadedNoteImage(
+  filename: string,
+  userId: string | null | undefined,
+): Promise<boolean> {
+  const imagePath = `/uploads/notes/${filename}`
+
+  const published = await prisma.note.findFirst({
+    where: {
+      isPublic: true,
+      trashedAt: null,
+      OR: [
+        { content: { contains: imagePath } },
+        { images: { contains: filename } },
+      ],
+    },
+    select: { id: true },
+  })
+  if (published) return true
+
+  if (!userId) return false
+
+  const owned = await prisma.note.findFirst({
+    where: {
+      userId,
+      trashedAt: null,
+      OR: [
+        { content: { contains: imagePath } },
+        { images: { contains: filename } },
+      ],
+    },
+    select: { id: true },
+  })
+  return !!owned
+}
diff --git a/memento-note/tests/unit/entitlements.test.ts b/memento-note/tests/unit/entitlements.test.ts
index 5dea940..cc982d2 100644
--- a/memento-note/tests/unit/entitlements.test.ts
+++ b/memento-note/tests/unit/entitlements.test.ts
@@ -142,7 +142,8 @@ describe('entitlements', () => {
       expect(result.reason).toBe('FEATURE_NOT_AVAILABLE');
     });
 
-    it('should fail-open when Redis is down', async () => {
+    it('should fail-open when Redis is down in non-production', async () => {
+      vi.stubEnv('NODE_ENV', 'development');
       mockActiveSubscription('BASIC');
       vi.mocked(redis.get).mockRejectedValue(new Error('Connection refused'));
 
@@ -150,6 +151,17 @@ describe('entitlements', () => {
 
       expect(result.allowed).toBe(true);
     });
+
+    it('should fail-closed when Redis is down in production', async () => {
+      vi.stubEnv('NODE_ENV', 'production');
+      mockActiveSubscription('BASIC');
+      vi.mocked(redis.get).mockRejectedValue(new Error('Connection refused'));
+
+      const result = await canUseFeature('user1', 'semantic_search');
+
+      expect(result.allowed).toBe(false);
+      expect(result.reason).toBe('SERVICE_UNAVAILABLE');
+    });
   });
 
   describe('checkEntitlementOrThrow', () => {