[glm-grade=A] fix(monitoring): DC-090 outage incidents follow displayed hysteresis status

checkForIncidents compared raw probe transitions while the dashboard badge
(DC-086) follows post-hysteresis displayed status. A single raw down blip
between two ups opened AND resolved a critical outage incident; a suppressed
up blip during a real outage resolved it early. Incidents now open/resolve
on displayed-vs-displayed transitions; previousDisplayed=null keeps legacy
raw semantics for direct callers. 6 new parity tests + legacy checkService
test moved to a 4-probe chain. Suite 2616/2616 (110).

Verdict: urn:ump:yc5rdlnmnmhch5audc5fifgbt6d7moi2stqfs5vidsbh6x6zkvgq

dashcaddy-api/__tests__/admin-invites.test.js

@@ -237,4 +237,49 @@ describe('DC-085: link-first admin invites', () => {
       .send({ email: 'a@x.com', ttlHours: 1 });
     expect(res.body.shareText).toContain('expires in 1h');
   });
-});
+
+  test('DC-089: SMTP-unconfigured warn log masks the invite email (no raw PII)', async () => {
+    mockEmailSender.isConfigured.mockReturnValueOnce(false);
+
+    const res = await request(app)
+      .post('/api/v1/auth/admin/invites')
+      .send({ email: 'friend@example.com', role: 'operator', sendEmail: true });
+
+    expect(res.status).toBe(200);
+    expect(res.body.deliveredVia).toBe('failed');
+    const warn = logCalls.find(c =>
+      c.level === 'warn' && c.topic === 'auth-invite-send'
+    );
+    expect(warn).toBeDefined();
+    // The raw address must not appear; the masked form must.
+    expect(JSON.stringify(warn.meta)).not.toContain('friend@example.com');
+    expect(warn.meta.email).toBe('fr****@example.com');
+  });
+
+  test('DC-089: invite-accepted info log masks the created user email (no raw PII)', async () => {
+    // Pre-authorize the email (POST /admin/users) so userStore.login doesn't
+    // reject with not_authorized — bootstrap already happened in beforeEach.
+    const preauth = await request(app)
+      .post('/api/v1/auth/admin/users')
+      .send({ email: 'newfriend@example.com' });
+    expect(preauth.status).toBe(200);
+
+    const issue = await request(app)
+      .post('/api/v1/auth/admin/invites')
+      .send({ email: 'newfriend@example.com', role: 'viewer' });
+    expect(issue.status).toBe(200);
+    const token = issue.body.acceptUrl.match(/invites\/([^/]+)\/accept/)[1];
+
+    const res = await request(app)
+      .post(`/api/v1/auth/invites/${token}/accept`)
+      .send({});
+
+    expect(res.status).toBe(200);
+    const info = logCalls.find(c =>
+      c.level === 'info' && c.msg === 'invite accepted, user created'
+    );
+    expect(info).toBeDefined();
+    expect(JSON.stringify(info.meta)).not.toContain('newfriend@example.com');
+    expect(info.meta.email).toBe('ne****@example.com');
+  });
+});

dashcaddy-api/__tests__/health-checker-incident-parity.test.js

@@ -0,0 +1,186 @@
+/**
+ * Tests for DC-090: outage incidents follow the DISPLAYED (post-hysteresis)
+ * status — the same signal that flips the dashboard badge.
+ *
+ *   - A single raw "down" blip that hysteresis suppresses opens NO outage
+ *     incident (the DC-089-noted raw-transition bug).
+ *   - A suppressed blip does not resolve a real open outage (UP_THRESHOLD=2).
+ *   - DOWN_THRESHOLD consecutive downs open exactly ONE outage incident.
+ *   - The incident payload carries the displayed snapshot, not the raw probe.
+ *   - Direct callers without hysteresis state keep legacy raw semantics.
+ *
+ * The probe() helper replicates checkService's exact call order: capture the
+ * pre-probe raw + displayed state, recordStatus (updates both maps), then
+ * checkForIncidents with both previous states.
+ */
+
+'use strict';
+
+const path = require('path');
+const fs = require('fs');
+const os = require('os');
+
+// Use an isolated data dir so test history doesn't pollute the real one.
+const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'dashcaddy-incpar-'));
+process.env.HEALTH_DATA_DIR = tmpDir;
+process.env.HEALTH_CONFIG_FILE = path.join(tmpDir, 'health-config.json');
+process.env.HEALTH_HISTORY_FILE = path.join(tmpDir, 'health-history.json');
+
+// Module exports a singleton instance, not a class. Reset per-test state by
+// replacing the relevant maps on the singleton in beforeEach.
+const healthCheckerSingleton = require('../src/monitoring/health-checker');
+const originalDownThreshold = process.env.HEALTH_DOWN_THRESHOLD;
+const originalUpThreshold = process.env.HEALTH_UP_THRESHOLD;
+
+function restoreEnv(name, value) {
+  if (value === undefined) delete process.env[name];
+  else process.env[name] = value;
+}
+
+function makeUp(serviceId = 'svc1') {
+  return {
+    serviceId,
+    timestamp: new Date().toISOString(),
+    status: 'up',
+    responseTime: 50,
+    statusCode: 200,
+    message: 'Service is healthy',
+    details: { headers: {}, bodyLength: 12 }
+  };
+}
+
+function makeDown(serviceId = 'svc1') {
+  return {
+    serviceId,
+    timestamp: new Date().toISOString(),
+    status: 'down',
+    responseTime: 50,
+    statusCode: 500,
+    message: 'fail',
+    details: { headers: {}, bodyLength: 0 }
+  };
+}
+
+describe('DC-090: outage incidents follow the displayed (hysteresis) status', () => {
+  let hc;
+  let incidentCreatedSpy;
+  let incidentResolvedSpy;
+
+  beforeEach(() => {
+    healthCheckerSingleton.displayedStatus = new Map();
+    healthCheckerSingleton.consecutiveSinceChange = new Map();
+    healthCheckerSingleton.currentStatus = new Map();
+    healthCheckerSingleton.history = {};
+    healthCheckerSingleton.incidents = [];
+    healthCheckerSingleton.removeAllListeners('incident-created');
+    healthCheckerSingleton.removeAllListeners('incident-resolved');
+    incidentCreatedSpy = jest.fn();
+    incidentResolvedSpy = jest.fn();
+    healthCheckerSingleton.on('incident-created', incidentCreatedSpy);
+    healthCheckerSingleton.on('incident-resolved', incidentResolvedSpy);
+    hc = healthCheckerSingleton;
+  });
+
+  afterEach(() => {
+    restoreEnv('HEALTH_DOWN_THRESHOLD', originalDownThreshold);
+    restoreEnv('HEALTH_UP_THRESHOLD', originalUpThreshold);
+  });
+
+  afterAll(() => {
+    fs.rmSync(tmpDir, { recursive: true, force: true });
+  });
+
+  // Replicates checkService's record+incident sequence for one raw probe.
+  function probe(status, config = {}) {
+    const previousStatus = hc.currentStatus.get(status.serviceId);
+    const previousDisplayed = hc.displayedStatus.get(status.serviceId) || null;
+    hc.recordStatus(status.serviceId, status);
+    hc.checkForIncidents(status.serviceId, status, config, previousStatus, previousDisplayed);
+  }
+
+  test('a single down blip between two ups opens NO outage incident', () => {
+    probe(makeUp());      // baseline: displayed up
+    probe(makeDown());    // blip — hysteresis keeps displayed up
+    probe(makeUp());      // recovered
+    expect(hc.incidents).toHaveLength(0);
+    expect(incidentCreatedSpy).not.toHaveBeenCalled();
+  });
+
+  test('DOWN_THRESHOLD consecutive downs open exactly one outage incident (critical)', () => {
+    probe(makeUp());
+    probe(makeDown());    // counter=1, displayed still up
+    probe(makeDown());    // counter=2 → displayed flips down → incident
+    expect(hc.incidents).toHaveLength(1);
+    const incident = hc.incidents[0];
+    expect(incident.type).toBe('outage');
+    expect(incident.severity).toBe('critical');
+    expect(incident.status).toBe('open');
+    expect(incidentCreatedSpy).toHaveBeenCalledTimes(1);
+
+    probe(makeDown());    // still down — no new transition, no second incident
+    expect(hc.incidents).toHaveLength(1);
+    expect(incident.occurrences).toBe(1);  // occurrences count displayed flips, not raw probes
+    expect(incidentCreatedSpy).toHaveBeenCalledTimes(1);
+  });
+
+  test('the outage incident payload carries the displayed snapshot, not the raw blip', () => {
+    probe(makeUp());
+    const blip = makeDown();
+    blip.statusCode = 599;
+    probe(blip);          // suppressed blip — must not appear in any incident
+    probe(makeDown());    // flip
+    expect(hc.incidents).toHaveLength(1);
+    // The incident's details snapshot is the probe that FLIPPED the displayed
+    // state (the second down), not the earlier suppressed blip.
+    expect(hc.incidents[0].details.statusCode).not.toBe(599);
+  });
+
+  test('a suppressed up blip does not resolve a real open outage (UP_THRESHOLD=2)', () => {
+    process.env.HEALTH_UP_THRESHOLD = '2';
+    jest.resetModules();
+    const hc2 = require('../src/monitoring/health-checker');
+    hc2.displayedStatus = new Map();
+    hc2.consecutiveSinceChange = new Map();
+    hc2.currentStatus = new Map();
+    hc2.history = {};
+    hc2.incidents = [];
+    hc2.removeAllListeners('incident-created');
+    hc2.removeAllListeners('incident-resolved');
+
+    const p2 = (status) => {
+      const prevRaw = hc2.currentStatus.get(status.serviceId);
+      const prevDisp = hc2.displayedStatus.get(status.serviceId) || null;
+      hc2.recordStatus(status.serviceId, status);
+      hc2.checkForIncidents(status.serviceId, status, {}, prevRaw, prevDisp);
+    };
+
+    p2(makeUp());
+    p2(makeDown());
+    p2(makeDown());       // displayed down → outage opens
+    expect(hc2.incidents).toHaveLength(1);
+    expect(hc2.incidents[0].status).toBe('open');
+
+    p2(makeUp());         // counter=1 < UP_THRESHOLD=2 → displayed still down
+    expect(hc2.displayedStatus.get('svc1').status).toBe('down');
+    expect(hc2.incidents[0].status).toBe('open');   // NOT resolved by the blip
+
+    p2(makeUp());         // counter=2 → displayed up → incident resolves
+    expect(hc2.displayedStatus.get('svc1').status).toBe('up');
+    expect(hc2.incidents[0].status).toBe('resolved');
+  });
+
+  test('legacy direct callers (no displayed state) keep raw transition semantics', () => {
+    hc.currentStatus.set('svc1', { status: 'up' });
+    const status = { status: 'down', timestamp: new Date().toISOString(), responseTime: 100 };
+    hc.checkForIncidents('svc1', status, {});   // 4-arg call, no previousDisplayed
+    expect(hc.incidents).toHaveLength(1);
+    expect(hc.incidents[0].type).toBe('outage');
+  });
+
+  test('slow-response detection still fires per-probe regardless of hysteresis', () => {
+    const slowUp = makeUp();
+    slowUp.responseTime = 6000;
+    probe(slowUp, { slowResponseThreshold: 5000 });
+    expect(hc.incidents.some(i => i.type === 'slow-response')).toBe(true);
+  });
+});

dashcaddy-api/__tests__/health-checker.test.js

@@ -204,15 +204,22 @@ describe('HealthChecker', () => {
     });
 
     it('opens and resolves an outage incident across real checkService transitions', async () => {
+      // DC-090: incidents follow the DISPLAYED (post-hysteresis) status.
+      // DOWN_THRESHOLD defaults to 2, so it takes two consecutive failed
+      // probes to flip displayed down and open the outage; one up probe
+      // (UP_THRESHOLD=1) resolves it.
       healthChecker._doRequest = jest.fn()
         .mockResolvedValueOnce({ healthy: true, statusCode: 200, message: 'ok', details: {} })
         .mockResolvedValueOnce({ healthy: false, statusCode: 500, message: 'down', details: {} })
+        .mockResolvedValueOnce({ healthy: false, statusCode: 500, message: 'down', details: {} })
         .mockResolvedValueOnce({ healthy: true, statusCode: 200, message: 'ok', details: {} });
 
       const config = { url: 'http://test.local' };
       await healthChecker.checkService('svc1', config);
       await healthChecker.checkService('svc1', config);
+      expect(healthChecker.incidents).toHaveLength(0);   // one down alone: suppressed blip
 
+      await healthChecker.checkService('svc1', config);  // second down flips displayed → open
       expect(healthChecker.incidents).toHaveLength(1);
       expect(healthChecker.incidents[0]).toMatchObject({
         serviceId: 'svc1',
@@ -220,7 +227,7 @@ describe('HealthChecker', () => {
         status: 'open'
       });
 
-      await healthChecker.checkService('svc1', config);
+      await healthChecker.checkService('svc1', config);  // up resolves
       expect(healthChecker.incidents[0].status).toBe('resolved');
       expect(healthChecker.incidents[0].resolvedAt).toBeDefined();
     });
@@ -591,6 +598,113 @@ describe('HealthChecker', () => {
     });
   });
 
+  describe('DC-088: removeService generation tombstones + incident closure', () => {
+    it('does not leak a serviceGenerations entry and records a tombstone', () => {
+      healthChecker.configureService('svc1', { url: 'http://test.local' });
+      expect(healthChecker.serviceGenerations.has('svc1')).toBe(true);
+
+      healthChecker.removeService('svc1');
+
+      expect(healthChecker.serviceGenerations.has('svc1')).toBe(false);
+      const tomb = healthChecker.removedGenerations.get('svc1');
+      expect(tomb).toBeDefined();
+      expect(tomb.generation).toBeGreaterThan(0);
+      expect(tomb.removedAt).toBeGreaterThan(0);
+    });
+
+    it('re-added service gets a strictly higher generation (no ABA)', () => {
+      healthChecker.configureService('svc1', { url: 'http://test.local' });
+      const gen1 = healthChecker.serviceGenerations.get('svc1');
+
+      healthChecker.removeService('svc1');
+      healthChecker.configureService('svc1', { url: 'http://test.local/v2' });
+
+      const gen2 = healthChecker.serviceGenerations.get('svc1');
+      expect(gen2).toBeGreaterThan(gen1);
+      expect(healthChecker.removedGenerations.has('svc1')).toBe(false);
+    });
+
+    it('closes open incidents for the removed service as resolved', () => {
+      healthChecker.saveConfig = jest.fn();
+      healthChecker.incidents.push({
+        id: 'incident-test-1',
+        serviceId: 'svc1',
+        type: 'outage',
+        status: 'open',
+        createdAt: new Date(Date.now() - 60_000).toISOString()
+      });
+      healthChecker.incidents.push({
+        id: 'incident-other',
+        serviceId: 'svc2',
+        type: 'outage',
+        status: 'open',
+        createdAt: new Date(Date.now() - 60_000).toISOString()
+      });
+      const resolvedSpy = jest.fn();
+      healthChecker.on('incident-resolved', resolvedSpy);
+
+      healthChecker.removeService('svc1');
+
+      const closed = healthChecker.incidents.find(i => i.id === 'incident-test-1');
+      expect(closed.status).toBe('resolved');
+      expect(closed.resolvedBy).toBe('service-removed');
+      expect(closed.resolvedAt).toBeDefined();
+      expect(closed.duration).toBeGreaterThan(0);
+      expect(healthChecker.incidents.find(i => i.id === 'incident-other').status).toBe('open');
+      expect(resolvedSpy).toHaveBeenCalledTimes(1);
+    });
+
+    it('in-flight probe captured before removal is discarded via tombstone', async () => {
+      let resolveProbe;
+      healthChecker.config.services.svc1 = { url: 'http://test.local' };
+      healthChecker._doRequest = jest.fn(() => new Promise(resolve => {
+        resolveProbe = resolve;
+      }));
+
+      const pending = healthChecker.checkService('svc1', healthChecker.config.services.svc1);
+      healthChecker.saveConfig = jest.fn();
+      healthChecker.removeService('svc1');
+      resolveProbe({ healthy: true, statusCode: 200, message: 'late', details: {} });
+      await pending;
+
+      expect(healthChecker.currentStatus.has('svc1')).toBe(false);
+      expect(healthChecker.consecutiveFailures.has('svc1')).toBe(false);
+    });
+
+    it('a rejected in-flight probe after removal does not re-create failure state', async () => {
+      let rejectProbe;
+      healthChecker.config.services.svc1 = { url: 'http://test.local' };
+      healthChecker._doRequest = jest.fn(() => new Promise((resolve, reject) => {
+        rejectProbe = reject;
+      }));
+
+      const pending = healthChecker.checkService('svc1', healthChecker.config.services.svc1);
+      healthChecker.saveConfig = jest.fn();
+      healthChecker.removeService('svc1');
+      rejectProbe(new Error('late failure'));
+      await pending;
+
+      expect(healthChecker.consecutiveFailures.has('svc1')).toBe(false);
+      expect(healthChecker.currentStatus.has('svc1')).toBe(false);
+    });
+
+    it('sweeps expired tombstones in cleanupHistory', () => {
+      healthChecker.removedGenerations.set('svc1', {
+        generation: 1,
+        removedAt: Date.now() - 60 * 60 * 1000 // 1h ago, TTL default 10m
+      });
+      healthChecker.removedGenerations.set('svc2', {
+        generation: 2,
+        removedAt: Date.now() // fresh
+      });
+
+      healthChecker.cleanupHistory();
+
+      expect(healthChecker.removedGenerations.has('svc1')).toBe(false);
+      expect(healthChecker.removedGenerations.has('svc2')).toBe(true);
+    });
+  });
+
   describe('cleanupHistory', () => {
     it('removes entries older than retention period', () => {
       const old = new Date(Date.now() - 35 * 24 * 60 * 60 * 1000).toISOString(); // 35 days ago

dashcaddy-api/routes/auth/admin.js

@@ -29,6 +29,7 @@ const platformPaths = require('../../platform-paths');
 const { createUserStore } = require('../../src/security/user-store');
 const { createInviteStore } = require('../../src/security/invite-store');
 const emailSender = require('../../src/auth/providers/email-sender');
+const AuthProvider = require('../../src/auth/providers/base');
 const { ValidationError, NotFoundError, ForbiddenError, PaymentRequiredError } = require('../../src/utilities/errors');
 const { ok, successMessage } = require('../../src/utils/responses');
 
@@ -254,7 +255,7 @@ module.exports = function({ asyncHandler, errorResponse, log, session, dataDir }
           // server log on every unconfigured-install invite.
           log.warn && log.warn('auth-invite-send',
             'invite send skipped: SMTP not configured (operator opted in)',
-            { inviteId: issued.id, email: issued.email });
+            { inviteId: issued.id, email: AuthProvider.maskEmail(issued.email) || '[unmaskable-email]' });
           deliveredVia = 'failed';
         }
       } catch (sendErr) {
@@ -369,7 +370,7 @@ module.exports = function({ asyncHandler, errorResponse, log, session, dataDir }
 
     log.info && log.info('auth', 'invite accepted, user created', {
       userId: userResult.user.id,
-      email: userResult.user.email,
+      email: AuthProvider.maskEmail(userResult.user.email) || '[unmaskable-email]',
       role: userResult.user.role,
       inviteId: invite.id,
     });

dashcaddy-api/src/monitoring/health-checker.js

@@ -32,6 +32,10 @@ const CHECK_INTERVAL = parseInt(process.env.HEALTH_CHECK_INTERVAL || '30000', 10
 const MAX_CHECK_INTERVAL = parseInt(process.env.HEALTH_CHECK_MAX_INTERVAL || '300000', 10); // 5 minutes max backoff
 const MAX_ENTRIES_PER_SERVICE = parseInt(process.env.HEALTH_MAX_ENTRIES || '500', 10); // Cap to prevent disk explosion
 const HISTORY_RETENTION_DAYS = parseInt(process.env.HEALTH_HISTORY_RETENTION || '30', 10);
+// DC-088: how long a removal tombstone outlives the removal itself. Only needs
+// to cover the max in-flight probe lifetime (timeout + scheduling headroom);
+// swept by cleanupHistory so removed services cannot accumulate map entries.
+const REMOVED_GENERATION_TTL_MS = parseInt(process.env.HEALTH_REMOVED_GEN_TTL || '600000', 10);
 
 // DC-086: hysteresis thresholds for badge display.
 // The raw probe result can flap on a single transient blip (Caddy reload,
@@ -72,6 +76,14 @@ class HealthChecker extends EventEmitter {
     this.serviceTimers = new Map(); // serviceId -> timer for per-service backoff
     // Invalidate probe completions that race with removal/reconfiguration.
     this.serviceGenerations = new Map(); // serviceId -> configuration generation
+    // DC-088: monotonically increasing sequence so generation numbers can never
+    // repeat across remove -> re-add cycles (prevents ABA on the stale check).
+    this.generationSeq = 0;
+    // DC-088: serviceId -> { generation, removedAt } tombstones. A live entry in
+    // serviceGenerations means the service is (re)configured; a tombstone with a
+    // HIGHER generation than the captured one marks the capture as stale. Entry
+    // is deleted when the service is removed, so the live map cannot leak.
+    this.removedGenerations = new Map();
   }
 
   /**
@@ -139,6 +151,21 @@ class HealthChecker extends EventEmitter {
     this.cleanupHistory();
   }
 
+  /**
+   * DC-088: true when a probe's captured generation no longer matches the
+   * service's current configuration state. A live serviceGenerations entry
+   * must match exactly. With no live entry the service was never configured
+   * in this process (disk-loaded / direct callers) — stale only if a removal
+   * tombstone with a HIGHER generation exists.
+   */
+  _isStaleCapture(serviceId, generation) {
+    if (this.serviceGenerations.has(serviceId)) {
+      return this.serviceGenerations.get(serviceId) !== generation;
+    }
+    const tomb = this.removedGenerations.get(serviceId);
+    return Boolean(tomb && tomb.generation > generation);
+  }
+
   /**
    * Check a single service
    */
@@ -160,7 +187,7 @@ class HealthChecker extends EventEmitter {
         details: result.details
       };
 
-      if ((this.serviceGenerations.get(serviceId) || 0) !== generation) {
+      if (this._isStaleCapture(serviceId, generation)) {
         return status;
       }
 
@@ -172,16 +199,14 @@ class HealthChecker extends EventEmitter {
       }
 
       const previousStatus = this.currentStatus.get(serviceId);
+      const previousDisplayed = this.displayedStatus.get(serviceId);
       this.recordStatus(serviceId, status);
-      this.checkForIncidents(serviceId, status, config, previousStatus);
+      this.checkForIncidents(serviceId, status, config, previousStatus, previousDisplayed);
 
       return status;
     } catch (error) {
       const responseTime = Date.now() - startTime;
 
-      // Increment failure count for backoff
-      this.consecutiveFailures.set(serviceId, (this.consecutiveFailures.get(serviceId) || 0) + 1);
-
       const status = {
         serviceId,
         timestamp: new Date().toISOString(),
@@ -190,13 +215,18 @@ class HealthChecker extends EventEmitter {
         error: error.message
       };
 
-      if ((this.serviceGenerations.get(serviceId) || 0) !== generation) {
+      if (this._isStaleCapture(serviceId, generation)) {
         return status;
       }
 
+      // Increment failure count for backoff — only after the result is known
+      // to be non-stale, so a removed service cannot re-create map entries.
+      this.consecutiveFailures.set(serviceId, (this.consecutiveFailures.get(serviceId) || 0) + 1);
+
       const previousStatus = this.currentStatus.get(serviceId);
+      const previousDisplayed = this.displayedStatus.get(serviceId);
       this.recordStatus(serviceId, status);
-      this.checkForIncidents(serviceId, status, config, previousStatus);
+      this.checkForIncidents(serviceId, status, config, previousStatus, previousDisplayed);
 
       return status;
     }
@@ -425,10 +455,27 @@ class HealthChecker extends EventEmitter {
   /**
    * Check for incidents (downtime, slow response, etc.)
    */
-  checkForIncidents(serviceId, status, config, previous = this.currentStatus.get(serviceId)) {
+  checkForIncidents(serviceId, status, config, previous = this.currentStatus.get(serviceId), previousDisplayed = null) {
     
-    // Check for status change (up -> down or down -> up)
+    // DC-090: outage incidents follow the DISPLAYED (post-hysteresis) status —
-    if (previous && previous.status !== status.status) {
+    // the same signal that flips the dashboard badge. A single raw "down"
+    // blip that hysteresis suppresses must not open a critical outage
+    // incident (and a suppressed blip must not resolve a real one). When the
+    // caller supplies the pre-probe displayed state (checkService always
+    // does), transitions are evaluated displayed-vs-displayed using the
+    // post-recordStatus state in this.displayedStatus. Direct callers with
+    // no hysteresis state (previousDisplayed === null) keep the legacy
+    // raw-probe transition semantics.
+    if (previousDisplayed) {
+      const displayed = this.displayedStatus.get(serviceId);
+      if (displayed && displayed.status !== previousDisplayed.status) {
+        if (displayed.status === 'down') {
+          this.createIncident(serviceId, 'outage', 'Service is down', displayed);
+        } else if (displayed.status === 'up') {
+          this.resolveIncident(serviceId, 'outage', displayed);
+        }
+      }
+    } else if (previous && previous.status !== status.status) {
       if (status.status === 'down') {
         this.createIncident(serviceId, 'outage', 'Service is down', status);
       } else if (status.status === 'up') {
@@ -660,7 +707,13 @@ class HealthChecker extends EventEmitter {
       this.config.services = {};
     }
 
-    this.serviceGenerations.set(serviceId, (this.serviceGenerations.get(serviceId) || 0) + 1);
+    // DC-088: monotonic instance-wide sequence — a re-added service can never
+    // recycle a previous generation number, and any older in-flight capture is
+    // invalidated by definition.
+    this.generationSeq += 1;
+    this.serviceGenerations.set(serviceId, this.generationSeq);
+    // Re-configuration supersedes any prior removal tombstone.
+    this.removedGenerations.delete(serviceId);
     this.config.services[serviceId] = {
       enabled: config.enabled !== false,
       name: config.name || serviceId,
@@ -683,12 +736,35 @@ class HealthChecker extends EventEmitter {
    * Remove service configuration
    */
   removeService(serviceId) {
-    this.serviceGenerations.set(serviceId, (this.serviceGenerations.get(serviceId) || 0) + 1);
+    // DC-088: tombstone the captured generation instead of leaking an entry.
+    // The live map entry is deleted; an in-flight probe captured BEFORE this
+    // point sees no live entry but a higher tombstone generation, so it is
+    // discarded. configureService clears the tombstone on re-add.
+    this.generationSeq += 1;
+    this.serviceGenerations.delete(serviceId);
+    this.removedGenerations.set(serviceId, {
+      generation: this.generationSeq,
+      removedAt: Date.now()
+    });
     if (this.config.services) {
       delete this.config.services[serviceId];
       this.saveConfig();
     }
 
+    // DC-088: open incidents for a removed service must not linger forever.
+    // Close them through the same resolve path a recovery would, annotated so
+    // history shows why (dashboard renders resolved incidents green + duration).
+    for (const incident of this.incidents) {
+      if (incident.serviceId === serviceId && incident.status === 'open') {
+        incident.status = 'resolved';
+        incident.resolvedAt = new Date().toISOString();
+        incident.duration = new Date(incident.resolvedAt) - new Date(incident.createdAt);
+        incident.resolvedBy = 'service-removed';
+        this.emit('incident-resolved', incident);
+        this.emit('log', 'info', `Incident closed by service removal: ${incident.id}`);
+      }
+    }
+
     this.currentStatus.delete(serviceId);
     this.displayedStatus.delete(serviceId);
     this.consecutiveSinceChange.delete(serviceId);
@@ -714,6 +790,18 @@ class HealthChecker extends EventEmitter {
         this.history[serviceId] = this.history[serviceId].slice(-MAX_ENTRIES_PER_SERVICE);
       }
     }
+
+    // DC-088: sweep expired removal tombstones. After the TTL no probe that
+    // captured a pre-removal generation can still be in flight (timeout is
+    // bounded by performHealthCheck), so the tombstone has done its job.
+    if (this.removedGenerations.size > 0) {
+      const now = Date.now();
+      for (const [serviceId, tomb] of this.removedGenerations) {
+        if (now - tomb.removedAt > REMOVED_GENERATION_TTL_MS) {
+          this.removedGenerations.delete(serviceId);
+        }
+      }
+    }
   }
 
   /**