src/mcpd/src/main.ts

@@ -474,16 +474,32 @@ async function main(): Promise<void> {
       },
     },
     secretRefResolver: secretResolverBridge,
+  }, {
+    // Cache-transition events go through pino so BACKEND_UNREACHABLE /
+    // BACKEND_RECOVERED land in ErrorLogBuffer and `mcpctl errors`.
+    log: {
+      warn: (obj: Record<string, unknown>, msg: string): void => { app.log.warn(obj, msg); },
+      info: (obj: Record<string, unknown>, msg: string): void => { app.log.info(obj, msg); },
+    },
   });
   const secretService = new SecretService(secretRepo, secretBackendService);
   const secretMigrateService = new SecretMigrateService(secretRepo, secretBackendService);
   const secretBackendRotator = new SecretBackendRotator({
     backends: secretBackendService,
     secrets: secretService,
+    log: {
+      error: (obj: Record<string, unknown>, msg: string): void => { app.log.error(obj, msg); },
+      warn: (msg: string): void => { app.log.warn(msg); },
+    },
   });
   const secretBackendRotatorLoop = new SecretBackendRotatorLoop({
     backends: secretBackendService,
     rotator: secretBackendRotator,
+    log: {
+      info: (msg: string): void => { app.log.info(`[rotator] ${msg}`); },
+      warn: (msg: string): void => { app.log.warn(`[rotator] ${msg}`); },
+      error: (obj: Record<string, unknown>, msg: string): void => { app.log.error(obj, msg); },
+    },
   });
   const llmAdapters = new LlmAdapterRegistry();
   // LlmService takes the adapter registry so create()/update() can run an

src/mcpd/src/services/secret-backend-rotator-loop.ts

@@ -26,7 +26,11 @@ export interface SecretBackendRotatorLoopDeps {
   /** Override in tests. */
   setTimeout?: (cb: () => void, ms: number) => NodeJS.Timeout;
   clearTimeout?: (t: NodeJS.Timeout) => void;
-  log?: { info: (msg: string) => void; warn: (msg: string) => void };
+  log?: {
+    info: (msg: string) => void;
+    warn: (msg: string) => void;
+    error: (obj: Record<string, unknown>, msg: string) => void;
+  };
 }
 
 const DEFAULT_INTERVAL_MS = 24 * 3600 * 1000;
@@ -36,7 +40,7 @@ export class SecretBackendRotatorLoop {
   private readonly timers = new Map<string, NodeJS.Timeout>();
   private readonly setT: (cb: () => void, ms: number) => NodeJS.Timeout;
   private readonly clearT: (t: NodeJS.Timeout) => void;
-  private readonly log: { info: (msg: string) => void; warn: (msg: string) => void };
+  private readonly log: NonNullable<SecretBackendRotatorLoopDeps['log']>;
   private stopped = false;
 
   constructor(private readonly deps: SecretBackendRotatorLoopDeps) {
@@ -44,9 +48,11 @@ export class SecretBackendRotatorLoop {
     this.clearT = deps.clearTimeout ?? ((t) => global.clearTimeout(t));
     this.log = deps.log ?? {
       // eslint-disable-next-line no-console
-      info: (m) => console.log(`[rotator] ${m}`),
+      info: (m: string): void => { console.log(`[rotator] ${m}`); },
       // eslint-disable-next-line no-console
-      warn: (m) => console.warn(`[rotator] ${m}`),
+      warn: (m: string): void => { console.warn(`[rotator] ${m}`); },
+      // eslint-disable-next-line no-console
+      error: (obj: Record<string, unknown>, m: string): void => { console.error(JSON.stringify({ level: 'fatal', ...obj, message: m })); },
     };
   }
 
@@ -70,13 +76,10 @@ export class SecretBackendRotatorLoop {
       this.deps.rotator.healthCheck(b.id)
         .then((res) => {
           if (!res.ok) {
-            // eslint-disable-next-line no-console
+            this.log.error(
-            console.error(JSON.stringify({
+              { kind: 'BACKEND_TOKEN_DEAD', backend: b.name },
-              level: 'fatal',
+              res.message ?? 'unknown',
-              kind: 'BACKEND_TOKEN_DEAD',
+            );
-              backend: b.name,
-              message: res.message ?? 'unknown',
-            }));
             this.log.warn(`backend '${b.name}' health check failed: ${res.message ?? 'unknown'}`);
           }
         })

src/mcpd/src/services/secret-backend-rotator.service.ts

@@ -53,18 +53,37 @@ export interface TokenMeta {
   rotatable?: boolean;
 }
 
+/**
+ * Structured logger. Must be a real pino-shaped logger in production: the
+ * `BACKEND_TOKEN_DEAD` fatals below used to go out via bare `console.error`,
+ * which bypasses the pino multistream feeding `ErrorLogBuffer` — so the one
+ * failure `mcpctl errors` exists to surface was the one it never saw.
+ */
+export interface RotatorLog {
+  error(obj: Record<string, unknown>, msg: string): void;
+  warn(msg: string): void;
+}
+
 export interface SecretBackendRotatorDeps {
   backends: SecretBackendService;
   secrets: SecretService;
   fetch?: typeof globalThis.fetch;
   now?: () => Date;
+  log?: RotatorLog;
 }
 
 export class SecretBackendRotator {
   private readonly now: () => Date;
+  private readonly log: RotatorLog;
 
   constructor(private readonly deps: SecretBackendRotatorDeps) {
     this.now = deps.now ?? (() => new Date());
+    this.log = deps.log ?? {
+      // eslint-disable-next-line no-console
+      error: (obj: Record<string, unknown>, msg: string): void => { console.error(JSON.stringify({ level: 'fatal', ...obj, message: msg })); },
+      // eslint-disable-next-line no-console
+      warn: (msg: string): void => { console.warn(msg); },
+    };
   }
 
   /** True iff this backend is a wizard-provisioned token-auth openbao with rotation enabled. */
@@ -144,15 +163,16 @@ export class SecretBackendRotator {
         : err;
       const wrappedMsg = wrapped instanceof Error ? wrapped.message : String(wrapped);
       await this.recordError(backendId, meta, wrappedMsg);
-      // Loud, structured log so the operator sees it in `kubectl logs deploy/mcpd`.
+      // Loud and structured, through pino so it also lands in ErrorLogBuffer
-      // eslint-disable-next-line no-console
+      // and therefore in `mcpctl errors` — not just in `kubectl logs`.
-      console.error(JSON.stringify({
+      this.log.error(
-        level: 'fatal',
+        {
           kind: tokenDead ? 'BACKEND_TOKEN_DEAD' : 'BACKEND_ROTATION_FAILED',
           backend: backend.name,
           url: cfg.url,
-        message: wrappedMsg,
+        },
-      }));
+        wrappedMsg,
+      );
       throw wrapped;
     }
 
@@ -164,7 +184,7 @@ export class SecretBackendRotator {
         // Log but don't fail the rotation — the new token is already live.
         const msg = err instanceof Error ? err.message : String(err);
         // eslint-disable-next-line no-console
-        console.warn(`rotation: revoke old accessor '${oldAccessor}' on backend '${backend.name}' failed (continuing): ${msg}`);
+        this.log.warn(`rotation: revoke old accessor '${oldAccessor}' on backend '${backend.name}' failed (continuing): ${msg}`);
       }
     }
 
@@ -249,7 +269,7 @@ export class SecretBackendRotator {
     } catch (inner) {
       // Don't mask the original error — just log the DB failure.
       // eslint-disable-next-line no-console
-      console.warn(`rotation: failed to persist lastRotationError (${message}): ${inner instanceof Error ? inner.message : String(inner)}`);
+      this.log.warn(`rotation: failed to persist lastRotationError (${message}): ${inner instanceof Error ? inner.message : String(inner)}`);
     }
   }
 }

src/mcpd/src/services/secret-backend.service.ts

@@ -2,6 +2,7 @@ import type { SecretBackend } from '@prisma/client';
 import type { ISecretBackendRepository } from '../repositories/secret-backend.repository.js';
 import type { SecretBackendDriver } from './secret-backends/types.js';
 import { createDriver, type DriverFactoryDeps } from './secret-backends/factory.js';
+import { CachingSecretBackendDriver, type CachingDriverOptions, type CacheStats } from './secret-backends/caching.js';
 import { NotFoundError, ConflictError } from './mcp-server.service.js';
 
 export class SecretBackendInUseError extends Error {
@@ -17,6 +18,7 @@ export class SecretBackendService {
   constructor(
     private readonly repo: ISecretBackendRepository,
     private readonly driverDeps: DriverFactoryDeps,
+    private readonly cacheOpts: CachingDriverOptions = {},
   ) {}
 
   async list(): Promise<SecretBackend[]> {
@@ -87,12 +89,34 @@ export class SecretBackendService {
     this.driverCache.delete(id);
   }
 
-  /** Get the driver for a given backend id, creating + caching on first call. */
+  /**
+   * Get the driver for a given backend id, creating + caching on first call.
+   *
+   * Remote backends are wrapped in `CachingSecretBackendDriver` so a backend
+   * outage degrades to "serving last known-good" instead of failing every
+   * caller. `plaintext` is deliberately NOT wrapped: its `read()` is an
+   * identity function over the DB row passed in by the caller, so a value cache
+   * there would serve pre-update data with nothing to invalidate it.
+   *
+   * Config changes invalidate for free — `update()` and `delete()` drop this
+   * map, and the value cache lives inside the driver instance, which is right:
+   * if `url`/`mount`/`pathPrefix` change, the cached names now mean something
+   * different.
+   */
   driverFor(backend: SecretBackend): SecretBackendDriver {
     const cached = this.driverCache.get(backend.id);
     if (cached) return cached;
-    const driver = createDriver(backend, this.driverDeps);
+    const base = createDriver(backend, this.driverDeps);
+    const driver = backend.type === 'plaintext'
+      ? base
+      : new CachingSecretBackendDriver(base, { ...this.cacheOpts, backendName: backend.name });
     this.driverCache.set(backend.id, driver);
     return driver;
   }
+
+  /** Cache state for a backend, for the health endpoint. Never exposes values. */
+  cacheStatsFor(backend: SecretBackend): CacheStats | undefined {
+    const driver = this.driverFor(backend);
+    return driver instanceof CachingSecretBackendDriver ? driver.stats() : undefined;
+  }
 }

src/mcpd/src/services/secret-backends/caching.ts

@@ -0,0 +1,198 @@
+/**
+ * Caching + stale-while-error decorator for any `SecretBackendDriver`.
+ *
+ * ## Why this exists
+ *
+ * `SecretService.resolveData()` calls `driver.read()` on *every* use, and every
+ * consumer funnels through it: server env resolution, LLM api keys, chat, git
+ * providers, code repos, webhooks. With a remote backend that means one network
+ * round-trip per secret per call, and — worse — any OpenBao blip propagates
+ * straight through. An instance that restarts during a blip fails env
+ * resolution, gets marked ERROR, and enters a 30s×5-then-5min backoff
+ * (`instance.service.ts`), so a few seconds of backend unavailability turns
+ * into minutes of degraded service.
+ *
+ * ## Semantics
+ *
+ * - **Fresh** (age < ttlMs): served from memory, no network.
+ * - **Stale-while-error**: past the TTL we always try the backend first. If it
+ *   answers, we refresh. If it fails *as a transport failure*
+ *   (`SecretBackendUnavailableError`), we serve the last known-good value
+ *   instead of throwing. This is the part that actually stops the ERROR storm.
+ * - **`SecretNotFoundError` evicts and rethrows.** Never served stale — that
+ *   would resurrect a deliberately deleted or revoked credential, which is
+ *   strictly worse than an outage.
+ * - **Any other error rethrows, without stale.** A 403 that survives a token
+ *   refresh means our grants were revoked; papering over it with cached data is
+ *   exactly how an upstream OpenBao re-init once went unnoticed for four days.
+ * - **No negative caching.** A miss must re-check; retry/backoff already lives
+ *   in the driver.
+ *
+ * The stale window is deliberately unbounded. A cap would mean a long outage
+ * eventually takes mcpd down anyway, which defeats the purpose, and the
+ * revoked-credential case is already handled definitively by `SecretNotFound`.
+ *
+ * ## What this does NOT fix
+ *
+ * A cold cache during an outage. If mcpd restarts while the backend is
+ * unreachable, nothing has a last-known-good value and secret-bearing servers
+ * fail to start — honestly, with a loud error. That is the correct behaviour:
+ * booting a server with an empty credential is the failure mode that had
+ * gitea-mcp reporting healthy while every authed call failed. The mitigation is
+ * to warm this cache at boot, not to invent a value.
+ *
+ * Values live in heap in cleartext for the TTL, so the map is bounded (LRU) and
+ * values are never logged.
+ */
+import type { SecretBackendDriver, SecretData, ExternalRef } from './types.js';
+import { SecretNotFoundError, SecretBackendUnavailableError } from './types.js';
+
+export interface CachingDriverLog {
+  warn(obj: Record<string, unknown>, msg: string): void;
+  info(obj: Record<string, unknown>, msg: string): void;
+}
+
+export interface CachingDriverOptions {
+  /** How long a value is served without consulting the backend. */
+  ttlMs?: number;
+  /** LRU bound — these are plaintext credentials held in memory. */
+  maxEntries?: number;
+  /** Backend name, for log context only. */
+  backendName?: string;
+  now?: () => number;
+  log?: CachingDriverLog;
+}
+
+interface CacheEntry {
+  data: SecretData;
+  fetchedAt: number;
+  /** Set when we last served this past its TTL because the backend was down. */
+  staleSince: number | undefined;
+}
+
+export const DEFAULT_CACHE_TTL_MS = 300_000;
+export const DEFAULT_CACHE_MAX_ENTRIES = 500;
+
+const NOOP_LOG: CachingDriverLog = { warn: () => undefined, info: () => undefined };
+
+export interface CacheStats {
+  entries: number;
+  servingStale: number;
+  oldestStaleSince: number | undefined;
+}
+
+export class CachingSecretBackendDriver implements SecretBackendDriver {
+  readonly kind: string;
+
+  private readonly entries = new Map<string, CacheEntry>();
+  private readonly ttlMs: number;
+  private readonly maxEntries: number;
+  private readonly backendName: string;
+  private readonly nowFn: () => number;
+  private readonly log: CachingDriverLog;
+
+  constructor(private readonly inner: SecretBackendDriver, opts: CachingDriverOptions = {}) {
+    this.kind = `cached:${inner.kind}`;
+    this.ttlMs = opts.ttlMs ?? DEFAULT_CACHE_TTL_MS;
+    this.maxEntries = opts.maxEntries ?? DEFAULT_CACHE_MAX_ENTRIES;
+    this.backendName = opts.backendName ?? inner.kind;
+    this.nowFn = opts.now ?? ((): number => Date.now());
+    this.log = opts.log ?? NOOP_LOG;
+  }
+
+  async read(input: { name: string; externalRef: ExternalRef; data: SecretData }): Promise<SecretData> {
+    const now = this.nowFn();
+    const cached = this.entries.get(input.name);
+
+    if (cached !== undefined && now - cached.fetchedAt < this.ttlMs) {
+      this.touch(input.name, cached);
+      return cached.data;
+    }
+
+    try {
+      const data = await this.inner.read(input);
+      if (cached?.staleSince !== undefined) {
+        // Edge-triggered: only on the transition back to healthy.
+        this.log.info(
+          { kind: 'BACKEND_RECOVERED', backend: this.backendName, secret: input.name,
+            staleForMs: now - cached.staleSince },
+          `secret backend '${this.backendName}' recovered; '${input.name}' is live again`,
+        );
+      }
+      this.store(input.name, { data, fetchedAt: now, staleSince: undefined });
+      return data;
+    } catch (err) {
+      if (err instanceof SecretNotFoundError) {
+        // Definitive. Drop the stale copy so we can never hand it out later.
+        this.entries.delete(input.name);
+        throw err;
+      }
+      if (!(err instanceof SecretBackendUnavailableError) || cached === undefined) {
+        throw err;
+      }
+      if (cached.staleSince === undefined) {
+        cached.staleSince = now;
+        this.log.warn(
+          { kind: 'BACKEND_UNREACHABLE', backend: this.backendName, secret: input.name,
+            ageMs: now - cached.fetchedAt, reason: err.message },
+          `secret backend '${this.backendName}' unreachable; serving cached '${input.name}'`,
+        );
+      }
+      this.touch(input.name, cached);
+      return cached.data;
+    }
+  }
+
+  async write(input: { name: string; data: SecretData }): Promise<{ externalRef: ExternalRef; storedData: SecretData }> {
+    const result = await this.inner.write(input);
+    // Cache what a subsequent read() would return — the values just written —
+    // not `storedData`, which remote drivers deliberately leave empty.
+    this.store(input.name, { data: input.data, fetchedAt: this.nowFn(), staleSince: undefined });
+    return result;
+  }
+
+  async delete(input: { name: string; externalRef: ExternalRef }): Promise<void> {
+    await this.inner.delete(input);
+    this.entries.delete(input.name);
+  }
+
+  async list(): Promise<Array<{ name: string; externalRef: ExternalRef }>> {
+    return this.inner.list();
+  }
+
+  async healthCheck(): Promise<{ ok: boolean; detail?: string }> {
+    return this.inner.healthCheck?.() ?? { ok: true, detail: 'no probe' };
+  }
+
+  async authCheck(): Promise<{ ok: boolean; detail?: string }> {
+    return this.inner.authCheck?.() ?? { ok: true, detail: 'no probe' };
+  }
+
+  /** Cache state for the backend health endpoint. Never exposes values. */
+  stats(): CacheStats {
+    let servingStale = 0;
+    let oldestStaleSince: number | undefined;
+    for (const e of this.entries.values()) {
+      if (e.staleSince === undefined) continue;
+      servingStale++;
+      if (oldestStaleSince === undefined || e.staleSince < oldestStaleSince) oldestStaleSince = e.staleSince;
+    }
+    return { entries: this.entries.size, servingStale, oldestStaleSince };
+  }
+
+  /** Move an entry to the MRU end of the insertion-ordered Map. */
+  private touch(name: string, entry: CacheEntry): void {
+    this.entries.delete(name);
+    this.entries.set(name, entry);
+  }
+
+  private store(name: string, entry: CacheEntry): void {
+    this.entries.delete(name);
+    this.entries.set(name, entry);
+    while (this.entries.size > this.maxEntries) {
+      const oldest = this.entries.keys().next();
+      if (oldest.done === true) break;
+      this.entries.delete(oldest.value);
+    }
+  }
+}

src/mcpd/src/services/secret-backends/openbao.ts

@@ -28,6 +28,7 @@
  */
 import { readFile } from 'node:fs/promises';
 import type { SecretBackendDriver, SecretData, ExternalRef, SecretRefResolver } from './types.js';
+import { SecretNotFoundError, SecretBackendUnavailableError } from './types.js';
 
 /** Best-effort read of a response body for error messages. Empty on parse failure. */
 async function bodyText(res: Response): Promise<string> {
@@ -77,10 +78,23 @@ export interface OpenBaoDriverDeps {
   readServiceAccountToken?: (path: string) => Promise<string>;
   /** Clock for cache TTL — overridable in tests. */
   now?: () => number;
+  /** Per-request timeout. Without one, an unreachable OpenBao hangs every caller. */
+  timeoutMs?: number;
+  /** Total attempts for retryable failures (network / 5xx / 429). 1 disables retry. */
+  maxAttempts?: number;
+  /** Base for exponential backoff between retries; full jitter is applied. */
+  backoffBaseMs?: number;
+  /** Test seam — real sleeps would make the retry tests take seconds. */
+  sleep?: (ms: number) => Promise<void>;
 }
 
 const SA_TOKEN_DEFAULT_PATH = '/var/run/secrets/kubernetes.io/serviceaccount/token';
 const TOKEN_RENEW_GRACE_MS = 60_000;
+const DEFAULT_TIMEOUT_MS = 5_000;
+const DEFAULT_MAX_ATTEMPTS = 3;
+const DEFAULT_BACKOFF_BASE_MS = 200;
+/** Statuses worth retrying: the backend is up but cannot answer right now. */
+const RETRYABLE_STATUS = new Set([429, 500, 502, 503, 504]);
 
 export class OpenBaoDriver implements SecretBackendDriver {
   readonly kind = 'openbao';
@@ -98,6 +112,10 @@ export class OpenBaoDriver implements SecretBackendDriver {
   private readonly resolver: SecretRefResolver | undefined;
   private readonly readSaToken: (path: string) => Promise<string>;
   private readonly nowFn: () => number;
+  private readonly timeoutMs: number;
+  private readonly maxAttempts: number;
+  private readonly backoffBaseMs: number;
+  private readonly sleep: (ms: number) => Promise<void>;
 
   // Cached vault token + when (epoch ms) it should be considered expired and refetched.
   private cachedToken: string | undefined;
@@ -131,13 +149,19 @@ export class OpenBaoDriver implements SecretBackendDriver {
     if (deps.secretRefResolver !== undefined) this.resolver = deps.secretRefResolver;
     this.readSaToken = deps.readServiceAccountToken ?? ((path) => readFile(path, 'utf-8').then((s) => s.trim()));
     this.nowFn = deps.now ?? (() => Date.now());
+    this.timeoutMs = deps.timeoutMs ?? DEFAULT_TIMEOUT_MS;
+    this.maxAttempts = deps.maxAttempts ?? DEFAULT_MAX_ATTEMPTS;
+    this.backoffBaseMs = deps.backoffBaseMs ?? DEFAULT_BACKOFF_BASE_MS;
+    this.sleep = deps.sleep ?? ((ms: number): Promise<void> => new Promise((r) => { setTimeout(r, ms); }));
   }
 
   async read(input: { name: string; externalRef: ExternalRef; data: SecretData }): Promise<SecretData> {
     const path = this.pathFor(input.name);
     const res = await this.request('GET', `/v1/${this.mount}/data/${path}`);
     if (res.status === 404) {
-      throw new Error(`OpenBao: secret '${input.name}' not found at ${path}`);
+      // Definitive answer, not a transport failure — the caching decorator
+      // must evict rather than serve a stale value here.
+      throw new SecretNotFoundError(`OpenBao: secret '${input.name}' not found at ${path}`);
     }
     if (!res.ok) throw new Error(`OpenBao read ${path}: HTTP ${res.status} ${await bodyText(res)}`);
     const body = await res.json() as { data?: { data?: SecretData } };
@@ -174,10 +198,50 @@ export class OpenBaoDriver implements SecretBackendDriver {
       }));
   }
 
+  /**
+   * LIVENESS. Deliberately unauthenticated: `sys/health` needs no token, and
+   * routing it through `request()` (as this used to) took a login first — so an
+   * expired role reported as "OpenBao is down", and every probe cost a login.
+   *
+   * OpenBao encodes its state in the status code, so map it rather than
+   * collapsing everything to ok/not-ok.
+   */
   async healthCheck(): Promise<{ ok: boolean; detail?: string }> {
     try {
-      const res = await this.request('GET', '/v1/sys/health');
+      const headers: Record<string, string> = {};
-      return { ok: res.ok, detail: `HTTP ${res.status}` };
+      if (this.namespace !== undefined) headers['X-Vault-Namespace'] = this.namespace;
+      const res = await this.fetchImpl(`${this.url}/v1/sys/health`, {
+        method: 'GET',
+        headers,
+        signal: AbortSignal.timeout(this.timeoutMs),
+      });
+      switch (res.status) {
+        case 200: return { ok: true, detail: 'active' };
+        case 429: return { ok: true, detail: 'standby' };
+        case 472: case 473: return { ok: true, detail: 'replication secondary' };
+        case 501: return { ok: false, detail: 'not initialized' };
+        case 503: return { ok: false, detail: 'sealed' };
+        default: return { ok: res.ok, detail: `HTTP ${String(res.status)}` };
+      }
+    } catch (err) {
+      return { ok: false, detail: err instanceof Error ? err.message : String(err) };
+    }
+  }
+
+  /**
+   * READINESS. Exercises the capability we actually depend on — read/list under
+   * `<mount>/<pathPrefix>/` — using the credentials we hold.
+   *
+   * `list()` rather than `auth/token/lookup-self` on purpose: lookup-self only
+   * proves the token exists, not that its policy still grants anything. The
+   * four-day outage in e51b924 was exactly a live token whose grants had been
+   * dropped by an upstream re-init. The existing read policy already permits
+   * this call, so it needs no bao-side change.
+   */
+  async authCheck(): Promise<{ ok: boolean; detail?: string }> {
+    try {
+      await this.list();
+      return { ok: true, detail: `readable at ${this.mount}/${this.pathPrefix}` };
     } catch (err) {
       return { ok: false, detail: err instanceof Error ? err.message : String(err) };
     }
@@ -206,11 +270,28 @@ export class OpenBaoDriver implements SecretBackendDriver {
     const loginUrl = `${this.url}/v1/auth/${this.k8sAuthMount}/login`;
     const headers: Record<string, string> = { 'Content-Type': 'application/json' };
     if (this.namespace !== undefined) headers['X-Vault-Namespace'] = this.namespace;
-    const res = await this.fetchImpl(loginUrl, {
+    // Bounded like every other call: a hung login is indistinguishable from a
+    // hung read to the caller, and this one used to have no timeout at all.
+    let res: Response;
+    try {
+      res = await this.fetchImpl(loginUrl, {
         method: 'POST',
         headers,
         body: JSON.stringify({ role: this.k8sRole, jwt }),
+        signal: AbortSignal.timeout(this.timeoutMs),
       });
+    } catch (err) {
+      throw new SecretBackendUnavailableError(
+        `OpenBao kubernetes login (role=${this.k8sRole!}): ${err instanceof Error ? err.message : String(err)}`,
+        { cause: err },
+      );
+    }
+    if (RETRYABLE_STATUS.has(res.status)) {
+      throw new SecretBackendUnavailableError(
+        `OpenBao kubernetes login (role=${this.k8sRole!}): HTTP ${String(res.status)}`,
+        { lastStatus: res.status },
+      );
+    }
     if (!res.ok) {
       const text = await res.text().catch(() => '');
       throw new Error(`OpenBao kubernetes login (role=${this.k8sRole!}): HTTP ${String(res.status)} ${text}`);
@@ -229,30 +310,77 @@ export class OpenBaoDriver implements SecretBackendDriver {
     return clientToken;
   }
 
-  private async request(method: string, path: string, body?: unknown): Promise<Response> {
+  /** Build a fresh RequestInit — headers must not be shared across attempts. */
-    const token = await this.getToken();
+  private buildInit(method: string, token: string, body?: unknown): RequestInit {
     const headers: Record<string, string> = { 'X-Vault-Token': token };
     if (this.namespace !== undefined) headers['X-Vault-Namespace'] = this.namespace;
     if (body !== undefined) headers['Content-Type'] = 'application/json';
-
+    const init: RequestInit = { method, headers, signal: AbortSignal.timeout(this.timeoutMs) };
-    const init: RequestInit = { method, headers };
     if (body !== undefined) init.body = JSON.stringify(body);
+    return init;
+  }
 
-    const res = await this.fetchImpl(`${this.url}${path}`, init);
+  /** Full-jitter exponential backoff, so concurrent callers don't resonate. */
+  private backoffFor(attempt: number): number {
+    return Math.random() * this.backoffBaseMs * Math.pow(2, attempt - 1);
+  }
+
+  private async request(method: string, path: string, body?: unknown): Promise<Response> {
+    const url = `${this.url}${path}`;
+    let lastStatus: number | undefined;
+    let lastErr: unknown;
+
+    for (let attempt = 1; attempt <= this.maxAttempts; attempt++) {
+      let res: Response;
+      try {
+        const token = await this.getToken();
+        res = await this.fetchImpl(url, this.buildInit(method, token, body));
+      } catch (err) {
+        // Network failure, DNS failure, or our own AbortSignal firing.
+        lastErr = err;
+        if (attempt < this.maxAttempts) {
+          await this.sleep(this.backoffFor(attempt));
+          continue;
+        }
+        throw new SecretBackendUnavailableError(
+          `OpenBao ${method} ${path}: ${err instanceof Error ? err.message : String(err)} (after ${String(attempt)} attempt(s))`,
+          { cause: err },
+        );
+      }
 
       // If the cached token expired between cache-check and request (k8s clock
-    // skew, server-side revocation, etc.), purge cache and retry once.
+      // skew, server-side revocation, etc.), purge cache and retry once. This
+      // is deliberately OUTSIDE the retry budget: it is a credential refresh,
+      // not a backend-unavailable condition, and it must stay single-shot so a
+      // genuinely revoked grant fails loudly instead of looping.
       if (res.status === 403 && this.cachedToken !== undefined) {
         this.cachedToken = undefined;
         this.cachedTokenExpiresAt = 0;
         const fresh = await this.getToken();
-      const retryHeaders: Record<string, string> = { 'X-Vault-Token': fresh };
+        return this.fetchImpl(url, this.buildInit(method, fresh, body));
-      if (this.namespace !== undefined) retryHeaders['X-Vault-Namespace'] = this.namespace;
-      if (body !== undefined) retryHeaders['Content-Type'] = 'application/json';
-      const retryInit: RequestInit = { method, headers: retryHeaders };
-      if (body !== undefined) retryInit.body = JSON.stringify(body);
-      return this.fetchImpl(`${this.url}${path}`, retryInit);
       }
+
+      // The backend is up but cannot answer right now — 503 is also what a
+      // sealed OpenBao returns, which used to be an immediate hard failure.
+      if (RETRYABLE_STATUS.has(res.status) && attempt < this.maxAttempts) {
+        lastStatus = res.status;
+        await this.sleep(this.backoffFor(attempt));
+        continue;
+      }
+      if (RETRYABLE_STATUS.has(res.status)) {
+        throw new SecretBackendUnavailableError(
+          `OpenBao ${method} ${path}: HTTP ${String(res.status)} after ${String(attempt)} attempt(s)`,
+          { lastStatus: res.status },
+        );
+      }
+
       return res;
     }
+
+    /* c8 ignore next 5 -- unreachable: every loop exit above returns or throws */
+    throw new SecretBackendUnavailableError(
+      `OpenBao ${method} ${path}: exhausted ${String(this.maxAttempts)} attempt(s)`,
+      lastErr !== undefined ? { cause: lastErr, ...(lastStatus !== undefined ? { lastStatus } : {}) } : (lastStatus !== undefined ? { lastStatus } : {}),
+    );
+  }
 }

src/mcpd/src/services/secret-backends/types.ts

@@ -46,8 +46,24 @@ export interface SecretBackendDriver {
   /** List everything the backend knows about. Used for migration + drift detection. */
   list(): Promise<Array<{ name: string; externalRef: ExternalRef }>>;
 
-  /** Optional: health probe. Used by `mcpctl describe secretbackend`. */
+  /**
+   * Optional LIVENESS probe: is the backend reachable at all?
+   *
+   * Must NOT require authentication — the whole point is to separate "the
+   * backend is down/sealed" from "our credentials stopped working". Compare
+   * `authCheck()`, which is the readiness half.
+   */
   healthCheck?(): Promise<{ ok: boolean; detail?: string }>;
+
+  /**
+   * Optional READINESS probe: can we actually read through this backend with
+   * the credentials we hold?
+   *
+   * A backend that answers `healthCheck()` but fails here is the exact shape of
+   * the incident where a re-initialised OpenBao left mcpd holding valid-looking
+   * tokens that granted nothing. Reporting one signal for both hides it.
+   */
+  authCheck?(): Promise<{ ok: boolean; detail?: string }>;
 }
 
 /** Stored config for a SecretBackend row; dispatched on `type`. */
@@ -66,3 +82,40 @@ export interface BackendRow {
 export interface SecretRefResolver {
   resolve(secretName: string, key: string): Promise<string>;
 }
+
+/**
+ * The backend gave a definitive answer: this secret (or key) does not exist.
+ *
+ * Callers may treat this as final. The caching decorator EVICTS on this and
+ * never serves a stale value for it — serving stale here would resurrect a
+ * deliberately deleted or revoked credential, which is strictly worse than an
+ * outage.
+ */
+export class SecretNotFoundError extends Error {
+  constructor(message: string, options?: { cause?: unknown }) {
+    super(message, options);
+    this.name = 'SecretNotFoundError';
+  }
+}
+
+/**
+ * The backend could not be reached or did not answer: DNS/TCP failure, request
+ * timeout, or an exhausted retry budget against 5xx/429.
+ *
+ * This is the ONLY error the caching decorator will serve a stale value for.
+ * The distinction has to be typed rather than string-matched: a mis-classified
+ * "not found" would resurrect deleted secrets, and a mis-classified auth
+ * failure would silently paper over a backend whose grants were revoked — the
+ * failure mode that let an OpenBao re-init break every secret write for four
+ * days (commit e51b924).
+ */
+export class SecretBackendUnavailableError extends Error {
+  /** HTTP status of the last attempt, when the failure was an HTTP response. */
+  readonly lastStatus: number | undefined;
+
+  constructor(message: string, options?: { cause?: unknown; lastStatus?: number }) {
+    super(message, options?.cause !== undefined ? { cause: options.cause } : undefined);
+    this.name = 'SecretBackendUnavailableError';
+    this.lastStatus = options?.lastStatus;
+  }
+}

src/mcpd/tests/secret-backends.test.ts

@@ -1,6 +1,7 @@
 import { describe, it, expect, vi } from 'vitest';
 import { PlaintextDriver } from '../src/services/secret-backends/plaintext.js';
 import { OpenBaoDriver } from '../src/services/secret-backends/openbao.js';
+import { SecretNotFoundError, SecretBackendUnavailableError } from '../src/services/secret-backends/types.js';
 
 describe('PlaintextDriver', () => {
   const driver = new PlaintextDriver({ listAllPlaintext: async () => [{ name: 'a', data: { k: 'v' } }] });
@@ -242,3 +243,91 @@ describe('OpenBaoDriver', () => {
     });
   });
 });
+
+describe('OpenBaoDriver: resilience', () => {
+  const resolver = { resolve: vi.fn(async () => 'test-vault-token') };
+  /** No real sleeping — otherwise the backoff tests take seconds. */
+  const noSleep = async (): Promise<void> => undefined;
+
+  function driverWith(fetchFn: ReturnType<typeof vi.fn>, opts: Record<string, unknown> = {}): OpenBaoDriver {
+    return new OpenBaoDriver(
+      { url: 'http://bao.example:8200', tokenSecretRef: { name: 'bao', key: 'token' } },
+      { fetch: fetchFn as unknown as typeof fetch, secretRefResolver: resolver, sleep: noSleep, ...opts },
+    );
+  }
+
+  it('maps a 404 read to SecretNotFoundError', async () => {
+    const fetchFn = vi.fn(async () => new Response('', { status: 404 }));
+    await expect(driverWith(fetchFn).read({ name: 'gone', externalRef: '', data: {} }))
+      .rejects.toThrow(SecretNotFoundError);
+  });
+
+  it('purges the token cache and retries once on 403 — outside the retry budget', async () => {
+    // This path existed but was never covered; it is the revocation/re-init case.
+    let n = 0;
+    const fetchFn = vi.fn(async () => {
+      n++;
+      if (n === 1) return new Response('', { status: 403 });
+      return new Response(JSON.stringify({ data: { data: { token: 'ok' } } }), { status: 200 });
+    });
+    const d = driverWith(fetchFn);
+    await expect(d.read({ name: 's', externalRef: '', data: {} })).resolves.toEqual({ token: 'ok' });
+    expect(fetchFn).toHaveBeenCalledTimes(2);
+  });
+
+  it('retries a 503 (sealed) and succeeds', async () => {
+    let n = 0;
+    const fetchFn = vi.fn(async () => {
+      n++;
+      if (n < 3) return new Response('', { status: 503 });
+      return new Response(JSON.stringify({ data: { data: { token: 'ok' } } }), { status: 200 });
+    });
+    await expect(driverWith(fetchFn).read({ name: 's', externalRef: '', data: {} }))
+      .resolves.toEqual({ token: 'ok' });
+    expect(fetchFn).toHaveBeenCalledTimes(3);
+  });
+
+  it('throws SecretBackendUnavailableError once the retry budget is exhausted', async () => {
+    const fetchFn = vi.fn(async () => new Response('', { status: 503 }));
+    await expect(driverWith(fetchFn, { maxAttempts: 3 }).read({ name: 's', externalRef: '', data: {} }))
+      .rejects.toThrow(SecretBackendUnavailableError);
+    expect(fetchFn).toHaveBeenCalledTimes(3);
+  });
+
+  it('classifies a network/abort failure as SecretBackendUnavailableError', async () => {
+    const fetchFn = vi.fn(async () => { throw new DOMException('timed out', 'TimeoutError'); });
+    await expect(driverWith(fetchFn, { maxAttempts: 2 }).read({ name: 's', externalRef: '', data: {} }))
+      .rejects.toThrow(SecretBackendUnavailableError);
+    expect(fetchFn).toHaveBeenCalledTimes(2);
+  });
+
+  it('passes an AbortSignal on every request', async () => {
+    const fetchFn = vi.fn(async () => new Response(JSON.stringify({ data: { data: {} } }), { status: 200 }));
+    await driverWith(fetchFn, { timeoutMs: 1234 }).read({ name: 's', externalRef: '', data: {} });
+    const [, init] = fetchFn.mock.calls[0] as [unknown, RequestInit];
+    expect(init.signal).toBeInstanceOf(AbortSignal);
+  });
+
+  it('healthCheck is unauthenticated and maps OpenBao status codes', async () => {
+    const cases: Array<[number, boolean, string]> = [
+      [200, true, 'active'],
+      [429, true, 'standby'],
+      [501, false, 'not initialized'],
+      [503, false, 'sealed'],
+    ];
+    for (const [status, ok, detail] of cases) {
+      const fetchFn = vi.fn(async () => new Response('', { status }));
+      const result = await driverWith(fetchFn).healthCheck();
+      expect(result).toEqual({ ok, detail });
+      // The whole point of the split: no token is minted for a liveness probe.
+      const [, init] = fetchFn.mock.calls[0] as [unknown, RequestInit];
+      expect((init.headers as Record<string, string>)['X-Vault-Token']).toBeUndefined();
+    }
+  });
+
+  it('authCheck reports false when the token can no longer list', async () => {
+    const fetchFn = vi.fn(async () => new Response('', { status: 403 }));
+    const result = await driverWith(fetchFn).authCheck();
+    expect(result.ok).toBe(false);
+  });
+});

src/mcpd/tests/secret-cache.test.ts

@@ -0,0 +1,198 @@
+import { describe, it, expect, vi } from 'vitest';
+import {
+  CachingSecretBackendDriver,
+  type CachingDriverLog,
+} from '../src/services/secret-backends/caching.js';
+import {
+  SecretNotFoundError,
+  SecretBackendUnavailableError,
+  type SecretBackendDriver,
+  type SecretData,
+} from '../src/services/secret-backends/types.js';
+
+/** Minimal fake backing driver whose read() behaviour the tests drive. */
+function makeInner(overrides: Partial<SecretBackendDriver> = {}): SecretBackendDriver & {
+  read: ReturnType<typeof vi.fn>;
+  write: ReturnType<typeof vi.fn>;
+  delete: ReturnType<typeof vi.fn>;
+} {
+  return {
+    kind: 'fake',
+    read: vi.fn(async () => ({ token: 'live' } as SecretData)),
+    write: vi.fn(async () => ({ externalRef: 'ref', storedData: {} as SecretData })),
+    delete: vi.fn(async () => undefined),
+    list: vi.fn(async () => []),
+    ...overrides,
+  } as never;
+}
+
+function makeLog(): CachingDriverLog & { warns: Array<Record<string, unknown>>; infos: Array<Record<string, unknown>> } {
+  const warns: Array<Record<string, unknown>> = [];
+  const infos: Array<Record<string, unknown>> = [];
+  return { warns, infos, warn: (o) => { warns.push(o); }, info: (o) => { infos.push(o); } };
+}
+
+const REQ = { name: 'gitea-creds', externalRef: 'secret/mcpctl/gitea-creds', data: {} };
+
+describe('CachingSecretBackendDriver', () => {
+  it('serves from cache within the TTL without touching the backend', async () => {
+    const inner = makeInner();
+    let now = 1_000;
+    const d = new CachingSecretBackendDriver(inner, { ttlMs: 5_000, now: () => now });
+
+    expect(await d.read(REQ)).toEqual({ token: 'live' });
+    now += 4_999;
+    expect(await d.read(REQ)).toEqual({ token: 'live' });
+
+    expect(inner.read).toHaveBeenCalledTimes(1);
+  });
+
+  it('refetches once the TTL has elapsed', async () => {
+    const inner = makeInner();
+    let now = 1_000;
+    const d = new CachingSecretBackendDriver(inner, { ttlMs: 5_000, now: () => now });
+
+    await d.read(REQ);
+    now += 5_001;
+    await d.read(REQ);
+
+    expect(inner.read).toHaveBeenCalledTimes(2);
+  });
+
+  it('serves the stale value when the backend is unavailable', async () => {
+    const inner = makeInner();
+    let now = 1_000;
+    const log = makeLog();
+    const d = new CachingSecretBackendDriver(inner, { ttlMs: 1_000, now: () => now, log, backendName: 'bao' });
+
+    await d.read(REQ);
+    inner.read.mockRejectedValue(new SecretBackendUnavailableError('bao down'));
+    now += 10_000;
+
+    // This is the whole point: no throw, so instance.service never marks ERROR.
+    expect(await d.read(REQ)).toEqual({ token: 'live' });
+    expect(log.warns[0]?.kind).toBe('BACKEND_UNREACHABLE');
+  });
+
+  it('logs BACKEND_UNREACHABLE only on the transition, not on every stale read', async () => {
+    const inner = makeInner();
+    let now = 1_000;
+    const log = makeLog();
+    const d = new CachingSecretBackendDriver(inner, { ttlMs: 1_000, now: () => now, log });
+
+    await d.read(REQ);
+    inner.read.mockRejectedValue(new SecretBackendUnavailableError('bao down'));
+    for (let i = 0; i < 5; i++) { now += 2_000; await d.read(REQ); }
+
+    expect(log.warns.filter((w) => w.kind === 'BACKEND_UNREACHABLE')).toHaveLength(1);
+  });
+
+  it('logs BACKEND_RECOVERED once the backend answers again', async () => {
+    const inner = makeInner();
+    let now = 1_000;
+    const log = makeLog();
+    const d = new CachingSecretBackendDriver(inner, { ttlMs: 1_000, now: () => now, log });
+
+    await d.read(REQ);
+    inner.read.mockRejectedValue(new SecretBackendUnavailableError('bao down'));
+    now += 2_000;
+    await d.read(REQ);
+
+    inner.read.mockResolvedValue({ token: 'rotated' });
+    now += 2_000;
+    expect(await d.read(REQ)).toEqual({ token: 'rotated' });
+    expect(log.infos.filter((i) => i.kind === 'BACKEND_RECOVERED')).toHaveLength(1);
+  });
+
+  it('NEVER serves stale for a deleted secret — evicts and rethrows', async () => {
+    // Regression guard. Serving stale here would resurrect a revoked
+    // credential, which is strictly worse than an outage.
+    const inner = makeInner();
+    let now = 1_000;
+    const d = new CachingSecretBackendDriver(inner, { ttlMs: 1_000, now: () => now });
+
+    await d.read(REQ);
+    inner.read.mockRejectedValue(new SecretNotFoundError('gone'));
+    now += 2_000;
+
+    await expect(d.read(REQ)).rejects.toThrow(SecretNotFoundError);
+    expect(d.stats().entries).toBe(0);
+
+    // And the entry really is gone — a later unavailable error has nothing to serve.
+    inner.read.mockRejectedValue(new SecretBackendUnavailableError('bao down'));
+    await expect(d.read(REQ)).rejects.toThrow(SecretBackendUnavailableError);
+  });
+
+  it('does not serve stale for a non-transport error (e.g. revoked grants)', async () => {
+    const inner = makeInner();
+    let now = 1_000;
+    const d = new CachingSecretBackendDriver(inner, { ttlMs: 1_000, now: () => now });
+
+    await d.read(REQ);
+    inner.read.mockRejectedValue(new Error('OpenBao read: HTTP 403 permission denied'));
+    now += 2_000;
+
+    await expect(d.read(REQ)).rejects.toThrow(/403/);
+  });
+
+  it('rethrows on a cold cache even when the backend is unavailable', async () => {
+    const inner = makeInner({ read: vi.fn(async () => { throw new SecretBackendUnavailableError('bao down'); }) as never });
+    const d = new CachingSecretBackendDriver(inner);
+
+    await expect(d.read(REQ)).rejects.toThrow(SecretBackendUnavailableError);
+  });
+
+  it('write() refreshes the cache so a read-after-write does not lag', async () => {
+    const inner = makeInner();
+    const d = new CachingSecretBackendDriver(inner, { ttlMs: 60_000 });
+
+    await d.read(REQ);
+    await d.write({ name: REQ.name, data: { token: 'brand-new' } });
+
+    expect(await d.read(REQ)).toEqual({ token: 'brand-new' });
+    expect(inner.read).toHaveBeenCalledTimes(1);
+  });
+
+  it('delete() evicts', async () => {
+    const inner = makeInner();
+    const d = new CachingSecretBackendDriver(inner, { ttlMs: 60_000 });
+
+    await d.read(REQ);
+    await d.delete({ name: REQ.name, externalRef: REQ.externalRef });
+
+    expect(d.stats().entries).toBe(0);
+  });
+
+  it('bounds the map with an LRU eviction', async () => {
+    const inner = makeInner();
+    const d = new CachingSecretBackendDriver(inner, { ttlMs: 60_000, maxEntries: 2 });
+
+    await d.read({ ...REQ, name: 'a' });
+    await d.read({ ...REQ, name: 'b' });
+    await d.read({ ...REQ, name: 'a' });   // 'a' becomes most-recently-used
+    await d.read({ ...REQ, name: 'c' });   // evicts 'b'
+
+    expect(d.stats().entries).toBe(2);
+    inner.read.mockClear();
+    await d.read({ ...REQ, name: 'a' });
+    expect(inner.read).not.toHaveBeenCalled();   // 'a' survived
+    await d.read({ ...REQ, name: 'b' });
+    expect(inner.read).toHaveBeenCalledTimes(1); // 'b' was evicted
+  });
+
+  it('reports stale count and age via stats()', async () => {
+    const inner = makeInner();
+    let now = 1_000;
+    const d = new CachingSecretBackendDriver(inner, { ttlMs: 1_000, now: () => now });
+
+    await d.read({ ...REQ, name: 'a' });
+    await d.read({ ...REQ, name: 'b' });
+    expect(d.stats()).toMatchObject({ entries: 2, servingStale: 0 });
+
+    inner.read.mockRejectedValue(new SecretBackendUnavailableError('down'));
+    now += 2_000;
+    await d.read({ ...REQ, name: 'a' });
+
+    expect(d.stats()).toMatchObject({ entries: 2, servingStale: 1, oldestStaleSince: 3_000 });
+  });
+});