diff --git a/dashcaddy-api/__tests__/csrf-protection.test.js b/dashcaddy-api/__tests__/csrf-protection.test.js
index b039f57..022e9ad 100644
--- a/dashcaddy-api/__tests__/csrf-protection.test.js
+++ b/dashcaddy-api/__tests__/csrf-protection.test.js
@@ -322,6 +322,89 @@ describe('CSRF Protection', () => {
 
       process.env.NODE_ENV = origEnv;
     });
+
+    // DC-058: differentiate "browser auto-retry" from "real probe" by the
+    // presence of the X-CSRF-Token header. The 403 response is identical in
+    // both branches; only the stderr log tag changes.
+    describe('DC-058: browser-auto-retry vs real-probe log tagging', () => {
+      let stderrSpy;
+      let origEnv;
+
+      beforeEach(() => {
+        origEnv = process.env.NODE_ENV;
+        process.env.NODE_ENV = 'production';
+        stderrSpy = jest.spyOn(process.stderr, 'write').mockImplementation(() => true);
+      });
+
+      afterEach(() => {
+        process.env.NODE_ENV = origEnv;
+        stderrSpy.mockRestore();
+      });
+
+      it('tags missing-cookie with [CSRF-debug] when X-CSRF-Token header also present (browser auto-retry)', () => {
+        const { req, res, next } = createMockReqRes({
+          method: 'POST', path: '/api/v1/backups/schedule',
+          headers: { cookie: '', 'x-csrf-token': 'some-signature-attempt' }
+        });
+        csrfValidationMiddleware(req, res, next);
+
+        // 403 response unchanged
+        expect(res.status).toHaveBeenCalledWith(403);
+        expect(res.json).toHaveBeenCalledWith(
+          expect.objectContaining({ error: expect.stringContaining('DC-100') })
+        );
+        // Log tag is [CSRF-debug]
+        expect(stderrSpy).toHaveBeenCalled();
+        const lastWrite = stderrSpy.mock.calls[stderrSpy.mock.calls.length - 1][0];
+        expect(lastWrite).toContain('[CSRF-debug]');
+        expect(lastWrite).toContain('browser auto-retry');
+        expect(lastWrite).not.toMatch(/^\[CSRF\][^-]/); // not bare [CSRF]
+      });
+
+      it('tags missing-cookie with [CSRF] when no X-CSRF-Token header present (real probe)', () => {
+        const { req, res, next } = createMockReqRes({
+          method: 'POST', path: '/api/v1/backups/schedule',
+          headers: { cookie: '' }
+        });
+        csrfValidationMiddleware(req, res, next);
+
+        expect(res.status).toHaveBeenCalledWith(403);
+        expect(stderrSpy).toHaveBeenCalled();
+        const lastWrite = stderrSpy.mock.calls[stderrSpy.mock.calls.length - 1][0];
+        expect(lastWrite).toContain('[CSRF]');
+        expect(lastWrite).not.toContain('[CSRF-debug]');
+        expect(lastWrite).not.toContain('browser auto-retry');
+      });
+
+      it('keeps [CSRF] tag when cookie present but header missing (curl probe with manual cookie)', () => {
+        const nonce = generateToken();
+        const { req, res, next } = createMockReqRes({
+          method: 'POST', path: '/api/v1/backups/schedule',
+          headers: { cookie: `${CSRF_COOKIE_NAME}=${nonce}` }
+        });
+        csrfValidationMiddleware(req, res, next);
+
+        expect(res.status).toHaveBeenCalledWith(403);
+        expect(stderrSpy).toHaveBeenCalled();
+        const lastWrite = stderrSpy.mock.calls[stderrSpy.mock.calls.length - 1][0];
+        expect(lastWrite).toContain('[CSRF]');
+        expect(lastWrite).not.toContain('[CSRF-debug]');
+      });
+
+      it('headerToken is read from x-csrf-token (lowercased by Express) — lowercase header triggers [CSRF-debug]', () => {
+        // Express/Node lowercases all incoming header keys, so production code
+        // only ever sees lowercase. We test the exact code path here.
+        const { req, res, next } = createMockReqRes({
+          method: 'POST', path: '/api/v1/backups/schedule',
+          headers: { cookie: '', 'x-csrf-token': 'some-signature-attempt' }
+        });
+        csrfValidationMiddleware(req, res, next);
+
+        expect(res.status).toHaveBeenCalledWith(403);
+        const lastWrite = stderrSpy.mock.calls[stderrSpy.mock.calls.length - 1][0];
+        expect(lastWrite).toContain('[CSRF-debug]');
+      });
+    });
   });
 
   describe('renewCSRFToken', () => {
diff --git a/dashcaddy-api/__tests__/routes/disk-space.routes.test.js b/dashcaddy-api/__tests__/routes/disk-space.routes.test.js
new file mode 100644
index 0000000..15ad430
--- /dev/null
+++ b/dashcaddy-api/__tests__/routes/disk-space.routes.test.js
@@ -0,0 +1,277 @@
+/**
+ * DC-059: disk-space POST /config threshold-ordering invariant.
+ *
+ * DiskSpaceMonitor._getBudgetStatus() returns the FIRST threshold the
+ * budget usage crosses, in the order
+ *   cleanupAggressivePct → criticalThresholdPct → warningThresholdPct.
+ * If a caller writes the three thresholds out of order
+ * (e.g. warningThresholdPct=95, criticalThresholdPct=60), the higher-
+ * priority branches become unreachable and the monitor silently
+ * misclassifies budget state — 'warning' would never fire even though the
+ * user set it as a threshold they care about.
+ *
+ * The fix lives in `routes/disk-space.js`: a `mergeAndCheckOrdering()`
+ * helper validates the *effective* (merged with live baseline) config
+ * against the invariant `warningThresholdPct < criticalThresholdPct <
+ * cleanupAggressivePct` BEFORE the route mutates diskSpaceMonitor.diskConfig.
+ *
+ * Tests cover:
+ *   1. Monotonic ascending order is accepted (happy path).
+ *   2. warningThresholdPct >= criticalThresholdPct is rejected with 400.
+ *   3. criticalThresholdPct >= cleanupAggressivePct is rejected with 400.
+ *   4. Partial updates work one field at a time without violating the
+ *      invariant against the current baseline.
+ *   5. Out-of-bounds numeric values are clamped to the same bounds the
+ *      original inline Math.min/Math.max chains enforced (50/60/70 → 99).
+ *   6. DiskSpaceMonitor.configure is NEVER called when the request is
+ *      rejected (no partial mutation).
+ *   7. The merged config returned to the client is the post-clamp value,
+ *      not the raw request body.
+ */
+
+const express = require('express');
+const http = require('http');
+
+const DEFAULT_CONFIG = {
+  enabled: true,
+  diskBudgetGB: 10,
+  warningThresholdPct: 80,
+  criticalThresholdPct: 90,
+  autoCleanup: true,
+  cleanupAggressivePct: 95,
+};
+
+function buildFakeDiskSpaceMonitor(initial = { ...DEFAULT_CONFIG }) {
+  const state = { ...initial };
+  return {
+    configure: jest.fn((updates) => {
+      Object.assign(state, updates);
+      return { ...state };
+    }),
+    getConfig: jest.fn(() => ({ ...state })),
+    getSnapshot: jest.fn(async () => ({})),
+    getDetailedBreakdown: jest.fn(async () => ({})),
+    performCleanup: jest.fn(async () => ({})),
+    // Test-only: peek at the internal state to confirm no mutation on rejection
+    _state: state,
+  };
+}
+
+function buildRouter(monitor) {
+  // Reset module cache so each test starts fresh
+  jest.resetModules();
+  const mod = require('../../routes/disk-space');
+  return mod({
+    diskSpaceMonitor: monitor,
+    asyncHandler: (fn) => async (req, res, next) => { // eslint-disable-line require-await
+      try { await fn(req, res, next); } catch (e) { next(e); }
+    },
+    log: { info: jest.fn(), warn: jest.fn(), error: jest.fn() },
+  });
+}
+
+function buildApp(router) {
+  const app = express();
+  app.use(express.json());
+  app.use((req, _res, next) => { next(); }); // strip auth
+  app.use('/', router);
+  // eslint-disable-next-line no-unused-vars
+  app.use((err, req, res, next) => {
+    const status = err.statusCode || err.status || 500;
+    res.status(status).json({
+      error: err.message,
+      code: err.code || 'ERR',
+      field: err.field || null,
+    });
+  });
+  return app;
+}
+
+function supertestFetch(app) {
+  return function (method, path, body) {
+    return new Promise((resolve, reject) => {
+      const server = app.listen(0, () => {
+        const { port } = server.address();
+        const data = body ? JSON.stringify(body) : null;
+        const req = http.request({
+          method,
+          hostname: '127.0.0.1',
+          port,
+          path,
+          headers: data ? { 'Content-Type': 'application/json', 'Content-Length': Buffer.byteLength(data) } : {},
+        }, (res) => {
+          let chunks = '';
+          res.on('data', (c) => { chunks += c; });
+          res.on('end', () => {
+            server.close();
+            let parsed;
+            try { parsed = JSON.parse(chunks); } catch { parsed = chunks; }
+            resolve({ status: res.statusCode, body: parsed });
+          });
+        });
+        req.on('error', (e) => { server.close(); reject(e); });
+        if (data) req.write(data);
+        req.end();
+      });
+    });
+  };
+}
+
+describe('routes/disk-space POST /config (DC-059 threshold ordering)', () => {
+  let monitor, app, fetch;
+
+  beforeEach(() => {
+    monitor = buildFakeDiskSpaceMonitor();
+    const router = buildRouter(monitor);
+    app = buildApp(router);
+    fetch = supertestFetch(app);
+  });
+
+  test('happy path — strict monotonic ascending order is accepted', async () => {
+    const res = await fetch('POST', '/config', {
+      warningThresholdPct: 75,
+      criticalThresholdPct: 88,
+      cleanupAggressivePct: 95,
+    });
+    expect(res.status).toBe(200);
+    expect(res.body.config).toEqual(expect.objectContaining({
+      warningThresholdPct: 75,
+      criticalThresholdPct: 88,
+      cleanupAggressivePct: 95,
+    }));
+    expect(monitor.configure).toHaveBeenCalledTimes(1);
+  });
+
+  test('warningThresholdPct >= criticalThresholdPct is rejected with 400', async () => {
+    const res = await fetch('POST', '/config', {
+      warningThresholdPct: 95,
+      criticalThresholdPct: 80,
+      cleanupAggressivePct: 99,
+    });
+    expect(res.status).toBe(400);
+    expect(res.body.error).toMatch(/warningThresholdPct.*strictly less than.*criticalThresholdPct/);
+    expect(res.body.field).toBe('warningThresholdPct');
+    // Critical invariant: monitor.configure was NEVER called.
+    expect(monitor.configure).not.toHaveBeenCalled();
+  });
+
+  test('criticalThresholdPct >= cleanupAggressivePct is rejected with 400', async () => {
+    const res = await fetch('POST', '/config', {
+      warningThresholdPct: 60,
+      criticalThresholdPct: 95,
+      cleanupAggressivePct: 80,
+    });
+    expect(res.status).toBe(400);
+    expect(res.body.error).toMatch(/criticalThresholdPct.*strictly less than.*cleanupAggressivePct/);
+    expect(res.body.field).toBe('criticalThresholdPct');
+    expect(monitor.configure).not.toHaveBeenCalled();
+  });
+
+  test('equal thresholds are rejected (strict <, not <=)', async () => {
+    const res = await fetch('POST', '/config', {
+      warningThresholdPct: 80,
+      criticalThresholdPct: 80,
+      cleanupAggressivePct: 90,
+    });
+    expect(res.status).toBe(400);
+    expect(monitor.configure).not.toHaveBeenCalled();
+  });
+
+  test('partial update — single field accepted against existing baseline', async () => {
+    // Defaults: warning=80, critical=90, aggressive=95. Raise warning to 85.
+    const res = await fetch('POST', '/config', { warningThresholdPct: 85 });
+    expect(res.status).toBe(200);
+    expect(res.body.config.warningThresholdPct).toBe(85);
+    expect(res.body.config.criticalThresholdPct).toBe(90);
+    expect(res.body.config.cleanupAggressivePct).toBe(95);
+  });
+
+  test('partial update — would violate invariant against baseline, rejected', async () => {
+    // Defaults: warning=80, critical=90, aggressive=95. Setting warning=95
+    // would collide with the existing critical=90 (warning >= critical).
+    const res = await fetch('POST', '/config', { warningThresholdPct: 95 });
+    expect(res.status).toBe(400);
+    expect(res.body.error).toMatch(/warningThresholdPct.*strictly less than.*criticalThresholdPct/);
+    expect(monitor.configure).not.toHaveBeenCalled();
+  });
+
+  test('partial update — succeeds after baseline was updated in a prior request', async () => {
+    // First request: bump warning from 80 → 85 (within current critical=90).
+    let res = await fetch('POST', '/config', { warningThresholdPct: 85 });
+    expect(res.status).toBe(200);
+    // Second request: now bump warning from 85 → 89. Still under critical=90.
+    res = await fetch('POST', '/config', { warningThresholdPct: 89 });
+    expect(res.status).toBe(200);
+    expect(monitor.configure).toHaveBeenCalledTimes(2);
+  });
+
+  test('partial update — would violate against the NEW baseline, rejected', async () => {
+    // Step 1: raise warning to 85.
+    let res = await fetch('POST', '/config', { warningThresholdPct: 85 });
+    expect(res.status).toBe(200);
+    // Step 2: try to raise warning to 95 — would collide with critical=90.
+    res = await fetch('POST', '/config', { warningThresholdPct: 95 });
+    expect(res.status).toBe(400);
+    // monitor.configure should have run exactly once (the accepted request).
+    expect(monitor.configure).toHaveBeenCalledTimes(1);
+  });
+
+  test('out-of-bounds values are clamped to documented ranges', async () => {
+    // Note: the three values must produce a valid monotonic ordering AFTER
+    // clamping. Setting warning=20 (→ 50), critical=200 (→ 99), aggressive=70
+    // would produce critical=99 > aggressive=70 which is rejected by the
+    // ordering check. Use values that clamp into a valid range.
+    const res = await fetch('POST', '/config', {
+      warningThresholdPct: 20,    // below warning min 50 → clamped to 50
+      criticalThresholdPct: 85,   // valid
+      cleanupAggressivePct: 200,  // above aggressive max 99 → clamped to 99
+    });
+    expect(res.status).toBe(200);
+    expect(res.body.config).toEqual(expect.objectContaining({
+      warningThresholdPct: 50,
+      criticalThresholdPct: 85,
+      cleanupAggressivePct: 99,
+    }));
+  });
+
+  test('non-numeric threshold values are silently dropped (legacy behaviour preserved)', async () => {
+    // Strings are not numbers → unchanged from baseline. Confirms the
+    // ordering check doesn\'t reject legitimate "I didn\'t change this" requests.
+    const res = await fetch('POST', '/config', {
+      warningThresholdPct: '80',
+    });
+    expect(res.status).toBe(200);
+    expect(res.body.config.warningThresholdPct).toBe(80); // baseline unchanged
+    expect(monitor.configure).toHaveBeenCalledWith({}); // empty updates
+  });
+
+  test('diskBudgetGB and autoCleanup updates still work alongside threshold validation', async () => {
+    const res = await fetch('POST', '/config', {
+      diskBudgetGB: 50,
+      autoCleanup: false,
+      warningThresholdPct: 81,
+    });
+    expect(res.status).toBe(200);
+    expect(res.body.config.diskBudgetGB).toBe(50);
+    expect(res.body.config.autoCleanup).toBe(false);
+    expect(res.body.config.warningThresholdPct).toBe(81);
+  });
+
+  test('rejected request does NOT mutate the live diskConfig', async () => {
+    const before = { ...monitor._state };
+    const res = await fetch('POST', '/config', {
+      warningThresholdPct: 95, // collides with critical=90
+    });
+    expect(res.status).toBe(400);
+    expect(monitor._state).toEqual(before);
+  });
+
+  test('POST /config with no thresholds in body is a no-op against baseline', async () => {
+    const res = await fetch('POST', '/config', { diskBudgetGB: 25 });
+    expect(res.status).toBe(200);
+    expect(res.body.config.diskBudgetGB).toBe(25);
+    expect(res.body.config.warningThresholdPct).toBe(80); // unchanged
+    expect(res.body.config.criticalThresholdPct).toBe(90); // unchanged
+    expect(res.body.config.cleanupAggressivePct).toBe(95); // unchanged
+  });
+});
\ No newline at end of file
diff --git a/dashcaddy-api/routes/disk-space.js b/dashcaddy-api/routes/disk-space.js
index 345733e..5bf208f 100644
--- a/dashcaddy-api/routes/disk-space.js
+++ b/dashcaddy-api/routes/disk-space.js
@@ -1,5 +1,6 @@
 const express = require('express');
 const { success, error: errorResponse } = require('../src/utils/responses');
+const { ValidationError } = require('../src/utilities/errors');
 
 /**
  * Disk space management routes
@@ -10,6 +11,76 @@ const { success, error: errorResponse } = require('../src/utils/responses');
  * POST /disk/config          — update disk budget settings
  * POST /disk/cleanup         — trigger manual cleanup (standard|aggressive|logs-only)
  */
+
+// DC-059: monotonic-ordering invariant for the three threshold percentages.
+// DiskSpaceMonitor._getBudgetStatus() walks them in order
+// (cleanupAggressivePct → criticalThresholdPct → warningThresholdPct) and
+// returns at the FIRST threshold the usage crosses. If a caller writes
+// them out of order (e.g. warningThresholdPct=95, criticalThresholdPct=60),
+// the higher-priority branches become unreachable and the monitor silently
+// misclassifies budget state. Validate against the *effective* config
+// (current value + incoming update for each field) so partial updates can
+// be applied one field at a time without violating the invariant.
+//
+// Clamp values to the same ranges the previous inline Math.min/Math.max
+// chains enforced (warning 50..99, critical 60..99, aggressive 70..99)
+// so we don't loosen the original bounds while adding the new check.
+const THRESHOLD_BOUNDS = Object.freeze({
+  warning:    { min: 50, max: 99 },
+  critical:   { min: 60, max: 99 },
+  aggressive: { min: 70, max: 99 },
+});
+
+function clampThreshold(name, value) {
+  const { min, max } = THRESHOLD_BOUNDS[name];
+  return Math.min(Math.max(value, min), max);
+}
+
+/**
+ * Apply a candidate update to a baseline config, then verify the three
+ * threshold percentages still satisfy
+ *   warningThresholdPct < criticalThresholdPct < cleanupAggressivePct.
+ * The POST /config endpoint accepts partial updates (single field at a
+ * time), so we merge into the live diskSpaceMonitor config first, then test
+ * the merged value. Returns the merged candidate on success; throws
+ * ValidationError if the ordering invariant would be violated.
+ *
+ * @param {Object} baseline - current effective config from diskSpaceMonitor
+ * @param {Object} candidate - the partial update being applied this request
+ * @returns {Object} merged candidate with thresholds clamped to bounds
+ */
+function mergeAndCheckOrdering(baseline, candidate) {
+  const next = { ...baseline };
+  if (typeof candidate.warningThresholdPct === 'number') {
+    next.warningThresholdPct = clampThreshold('warning', candidate.warningThresholdPct);
+  }
+  if (typeof candidate.criticalThresholdPct === 'number') {
+    next.criticalThresholdPct = clampThreshold('critical', candidate.criticalThresholdPct);
+  }
+  if (typeof candidate.cleanupAggressivePct === 'number') {
+    next.cleanupAggressivePct = clampThreshold('aggressive', candidate.cleanupAggressivePct);
+  }
+  if (!(next.warningThresholdPct < next.criticalThresholdPct)) {
+    throw new ValidationError(
+      `warningThresholdPct (${next.warningThresholdPct}) must be strictly less than criticalThresholdPct (${next.criticalThresholdPct})`,
+      'warningThresholdPct'
+    );
+  }
+  if (!(next.criticalThresholdPct < next.cleanupAggressivePct)) {
+    throw new ValidationError(
+      `criticalThresholdPct (${next.criticalThresholdPct}) must be strictly less than cleanupAggressivePct (${next.cleanupAggressivePct})`,
+      'criticalThresholdPct'
+    );
+  }
+  // Return only the fields the caller asked to change (preserves partial-
+  // update semantics; diskSpaceMonitor.configure does its own merge).
+  const out = {};
+  if (typeof candidate.warningThresholdPct === 'number') out.warningThresholdPct = next.warningThresholdPct;
+  if (typeof candidate.criticalThresholdPct === 'number') out.criticalThresholdPct = next.criticalThresholdPct;
+  if (typeof candidate.cleanupAggressivePct === 'number') out.cleanupAggressivePct = next.cleanupAggressivePct;
+  return out;
+}
+
 module.exports = function({ diskSpaceMonitor, asyncHandler, log }) {
   const router = express.Router();
 
@@ -36,9 +107,16 @@ module.exports = function({ diskSpaceMonitor, asyncHandler, log }) {
 
     const updates = {};
     if (typeof diskBudgetGB === 'number' && diskBudgetGB > 0) updates.diskBudgetGB = Math.min(diskBudgetGB, 1000);
-    if (typeof warningThresholdPct === 'number') updates.warningThresholdPct = Math.min(Math.max(warningThresholdPct, 50), 99);
-    if (typeof criticalThresholdPct === 'number') updates.criticalThresholdPct = Math.min(Math.max(criticalThresholdPct, 60), 99);
-    if (typeof cleanupAggressivePct === 'number') updates.cleanupAggressivePct = Math.min(Math.max(cleanupAggressivePct, 70), 99);
+    // DC-059: threshold percentages must satisfy a strict monotonic order
+    // (warning < critical < aggressive) so _getBudgetStatus() reaches the
+    // correct branch. mergeAndCheckOrdering() validates against the live
+    // baseline, so partial updates that violate the invariant are rejected
+    // BEFORE we mutate diskSpaceMonitor.diskConfig.
+    const thresholdUpdates = mergeAndCheckOrdering(
+      diskSpaceMonitor.getConfig(),
+      { warningThresholdPct, criticalThresholdPct, cleanupAggressivePct }
+    );
+    Object.assign(updates, thresholdUpdates);
     if (typeof autoCleanup === 'boolean') updates.autoCleanup = autoCleanup;
     if (typeof enabled === 'boolean') updates.enabled = enabled;
 
diff --git a/dashcaddy-api/src/security/csrf-protection.js b/dashcaddy-api/src/security/csrf-protection.js
index 97cc7f4..ad7581f 100644
--- a/dashcaddy-api/src/security/csrf-protection.js
+++ b/dashcaddy-api/src/security/csrf-protection.js
@@ -214,14 +214,30 @@ function csrfValidationMiddleware(req, res, next) {
     return next();
   }
 
-  // Validate both values exist
+  // DC-058: differentiate "browser auto-retry" from "real probe" using the
+  // X-CSRF-Token header as a signal. The dashboard JS in status/js/globals.js
+  // secureFetch() pre-fetches /api/v1/csrf-token (which sets the CSRF cookie
+  // via csrfCookieMiddleware) before posting; if the GET raced with container
+  // restart OR the user cleared cookies mid-session, the POST can arrive with
+  // a header but no cookie. secureFetch catches the 403 and auto-retries
+  // with a fresh token (lines 225-238 of globals.js). For these "has header
+  // but no cookie" misses, tag the log line [CSRF-debug] — operators can
+  // grep them out as expected noise. A request with NEITHER cookie NOR
+  // header (curl probe, exploit scanner, broken client) keeps the louder
+  // [CSRF] tag.
   if (!cookieNonce) {
-    process.stderr.write(`[CSRF] Missing CSRF cookie: ${method} ${req.path} from ${req.ip}\n`);
+    const isLikelyBrowserAutoRetry = !!headerToken;
+    const tag = isLikelyBrowserAutoRetry ? '[CSRF-debug]' : '[CSRF]';
+    process.stderr.write(`${tag} Missing CSRF cookie: ${method} ${req.path} from ${req.ip}` +
+      (isLikelyBrowserAutoRetry ? ' (browser auto-retry — header present, expect self-heal)' : '') + '\n');
     return errorResponse(res, 403, '[DC-100] CSRF token missing', {
       message: 'CSRF cookie not found. Please refresh the page (Ctrl+Shift+R) and try again.'
     });
   }
 
+  // Cookie present but no header — a real browser POST always sends both, so
+  // header-less is suspicious (curl probe with manual cookie, misconfigured
+  // client). Keep WARN level.
   if (!headerToken) {
     process.stderr.write(`[CSRF] Missing CSRF header: ${method} ${req.path} from ${req.ip}\n`);
     return errorResponse(res, 403, '[DC-100] CSRF token missing', {