diff --git a/tests/web/pi-runtime.test.ts b/tests/web/pi-runtime.test.ts
index ae6f3f78..92d7bcef 100644
--- a/tests/web/pi-runtime.test.ts
+++ b/tests/web/pi-runtime.test.ts
@@ -352,6 +352,51 @@ test("stale expected Session fails before prompt dispatch", async () => {
   assert.equal(session.calls.length, 0);
 });
 
+test("provider auth projection is bounded and never serializes credentials", () => {
+  const secret = "sk-must-never-reach-web";
+  const providers = Array.from({ length: 252 }, (_, index) => ({
+    id: index === 0 ? "invalid\u0000provider" : `provider-${index}`,
+    name: index === 1 ? "n".repeat(500) : `Provider ${index}`,
+    auth: {
+      apiKey: { secret },
+      ...(index % 2 === 0 ? { oauth: { token: secret } } : {}),
+    },
+  }));
+  const modelRuntime = {
+    getProviders: () => providers,
+    getProviderAuthStatus: () => ({
+      configured: true,
+      source: "stored" as const,
+      label: secret,
+    }),
+    isUsingSubscription: (id: string) => id === "provider-2",
+  };
+  const runtime = Object.create(PiWebRuntime.prototype) as {
+    runtime: { services: { modelRuntime: typeof modelRuntime } };
+    listProviderAuth: PiWebRuntime["listProviderAuth"];
+  };
+  runtime.runtime = { services: { modelRuntime } };
+
+  const projection = runtime.listProviderAuth();
+  assert.equal(projection.providers.length, 250);
+  assert.equal(projection.truncation.providersOmitted, 2);
+  assert.equal(projection.truncation.namesTruncated, 1);
+  assert.equal(projection.truncation.truncated, true);
+  assert.deepEqual(projection.providers[0], {
+    id: "provider-1",
+    name: `${"n".repeat(159)}…`,
+    authMethods: ["api_key"],
+    configured: true,
+    source: "stored",
+    subscription: false,
+    nameTruncated: true,
+  });
+  assert.deepEqual(projection.providers[1]?.authMethods, ["api_key", "oauth"]);
+  assert.equal(projection.providers[1]?.subscription, true);
+  assert.doesNotMatch(JSON.stringify(projection), /sk-must-never-reach-web/u);
+  assert.doesNotMatch(JSON.stringify(projection), /label|token|secret/u);
+});
+
 test("model selection and Session activation are serialized", async () => {
   const applied = deferred();
   const model = { provider: "fixture", id: "model-a", name: "Model A" };
diff --git a/tests/web/web-host.test.ts b/tests/web/web-host.test.ts
index d80df4fa..59924a00 100644
--- a/tests/web/web-host.test.ts
+++ b/tests/web/web-host.test.ts
@@ -65,6 +65,25 @@ test("serves workspaces through a runtime isolated from terminal sessions", asyn
     },
     switchSession: async () => ({ cancelled: false }),
     listModels: () => [],
+    listProviderAuth: () => ({
+      providers: [
+        {
+          id: "fixture",
+          name: "Fixture",
+          authMethods: ["api_key"],
+          configured: true,
+          source: "environment",
+          subscription: false,
+          nameTruncated: false,
+        },
+      ],
+      truncation: {
+        truncated: false,
+        providersOmitted: 0,
+        namesTruncated: 0,
+        maxProviders: 250,
+      },
+    }),
     setModel: async () => {
       throw new WebRuntimeRequestError(
         "Model is not available",
@@ -266,6 +285,30 @@ test("serves workspaces through a runtime isolated from terminal sessions", asyn
     });
     assert.equal(modelsResponse.status, 200);
     assert.deepEqual((await modelsResponse.json()).models, snapshot.models);
+    const providerAuthResponse = await fetch(
+      `${launched.origin}/api/providers/auth-status`,
+      { headers: authorized },
+    );
+    assert.equal(providerAuthResponse.status, 200);
+    assert.deepEqual(await providerAuthResponse.json(), {
+      providers: [
+        {
+          id: "fixture",
+          name: "Fixture",
+          authMethods: ["api_key"],
+          configured: true,
+          source: "environment",
+          subscription: false,
+          nameTruncated: false,
+        },
+      ],
+      truncation: {
+        truncated: false,
+        providersOmitted: 0,
+        namesTruncated: 0,
+        maxProviders: 250,
+      },
+    });
     const unavailableModel = await fetch(`${launched.origin}/api/model`, {
       method: "POST",
       headers: authorized,
diff --git a/web/host/web-host.ts b/web/host/web-host.ts
index 6203e647..8c449a97 100644
--- a/web/host/web-host.ts
+++ b/web/host/web-host.ts
@@ -557,6 +557,15 @@ export class WebHost {
     }
     if (url.pathname === "/api/models")
       return this.json(response, 200, { models: this.runtime.listModels() });
+    if (url.pathname === "/api/providers/auth-status") {
+      if (!this.runtime.listProviderAuth) {
+        return this.json(response, 501, {
+          code: "PROVIDER_AUTH_STATUS_UNAVAILABLE",
+          error: "provider authentication status is unavailable",
+        });
+      }
+      return this.json(response, 200, this.runtime.listProviderAuth());
+    }
     if (url.pathname === "/api/snapshot") {
       const cursor = this.sequence;
       const projection = await this.adapter.getSnapshot(
diff --git a/web/runtime/pi-runtime.ts b/web/runtime/pi-runtime.ts
index cf792d39..7f155dee 100644
--- a/web/runtime/pi-runtime.ts
+++ b/web/runtime/pi-runtime.ts
@@ -17,6 +17,8 @@ import {
 import {
   type WebModelSelectionOptions,
   type WebPromptOptions,
+  type WebProviderAuthProjection,
+  type WebProviderAuthSource,
   type WebRuntimeController,
   type WebRuntimeEvent,
   type WebSessionCreationOptions,
@@ -36,6 +38,18 @@ import {
 
 const STARTUP_TIMEOUT_MS = 15_000;
 const BOOTSTRAP_WORKSPACE_DIRECTORY = ".bootstrap-workspace";
+const WEB_MAX_PROVIDER_AUTH_ITEMS = 250;
+const WEB_MAX_PROVIDER_AUTH_SCANNED = 1_024;
+const WEB_MAX_PROVIDER_ID_LENGTH = 160;
+const WEB_MAX_PROVIDER_NAME_LENGTH = 160;
+const WEB_PROVIDER_AUTH_SOURCES = new Set<WebProviderAuthSource>([
+  "stored",
+  "runtime",
+  "environment",
+  "fallback",
+  "models_json_key",
+  "models_json_command",
+]);
 
 type PromptTrace = {
   commandId: string;
@@ -49,6 +63,24 @@ function errorText(error: unknown) {
   return error instanceof Error ? error.message : String(error);
 }
 
+function safeProviderId(value: string) {
+  return value.length > 0 &&
+    value.length <= WEB_MAX_PROVIDER_ID_LENGTH &&
+    !/[\u0000-\u001f\u007f]/u.test(value)
+    ? value
+    : undefined;
+}
+
+function boundedProviderName(value: string) {
+  const sanitized = value.replace(/[\u0000-\u001f\u007f]/gu, " ");
+  return sanitized.length <= WEB_MAX_PROVIDER_NAME_LENGTH
+    ? { value: sanitized, truncated: false }
+    : {
+        value: `${sanitized.slice(0, WEB_MAX_PROVIDER_NAME_LENGTH - 1)}…`,
+        truncated: true,
+      };
+}
+
 async function canonicalDirectory(path: string) {
   const canonical = await realpath(resolve(path));
   if (!(await stat(canonical)).isDirectory()) {
@@ -194,6 +226,61 @@ export class PiWebRuntime implements WebRuntimeController {
     }));
   }
 
+  listProviderAuth(): WebProviderAuthProjection {
+    const modelRuntime = this.runtime.services.modelRuntime;
+    const allProviders = modelRuntime.getProviders();
+    const providers = allProviders.slice(0, WEB_MAX_PROVIDER_AUTH_SCANNED);
+    const projection: WebProviderAuthProjection["providers"][number][] = [];
+    let omitted = Math.max(
+      0,
+      allProviders.length - WEB_MAX_PROVIDER_AUTH_SCANNED,
+    );
+    let namesTruncated = 0;
+    for (const provider of providers) {
+      if (projection.length >= WEB_MAX_PROVIDER_AUTH_ITEMS) {
+        omitted++;
+        continue;
+      }
+      try {
+        const id = safeProviderId(provider.id);
+        if (!id) {
+          omitted++;
+          continue;
+        }
+        const name = boundedProviderName(provider.name || id);
+        if (name.truncated) namesTruncated++;
+        const status = modelRuntime.getProviderAuthStatus(id);
+        const source =
+          status.source && WEB_PROVIDER_AUTH_SOURCES.has(status.source)
+            ? status.source
+            : undefined;
+        projection.push({
+          id,
+          name: name.value,
+          authMethods: [
+            ...(provider.auth.apiKey ? (["api_key"] as const) : []),
+            ...(provider.auth.oauth ? (["oauth"] as const) : []),
+          ],
+          configured: status.configured,
+          ...(source ? { source } : {}),
+          subscription: modelRuntime.isUsingSubscription(id),
+          nameTruncated: name.truncated,
+        });
+      } catch {
+        omitted++;
+      }
+    }
+    return {
+      providers: projection,
+      truncation: {
+        truncated: omitted > 0 || namesTruncated > 0,
+        providersOmitted: omitted,
+        namesTruncated,
+        maxProviders: WEB_MAX_PROVIDER_AUTH_ITEMS,
+      },
+    };
+  }
+
   setModel(
     provider: string,
     modelId: string,
diff --git a/web/runtime/types.ts b/web/runtime/types.ts
index 2b66c3f0..eb582987 100644
--- a/web/runtime/types.ts
+++ b/web/runtime/types.ts
@@ -1,6 +1,34 @@
 import type { SessionManager } from "@earendil-works/pi-coding-agent";
 import type { WebModelSummary } from "../protocol/types.ts";
 
+export type WebProviderAuthSource =
+  | "stored"
+  | "runtime"
+  | "environment"
+  | "fallback"
+  | "models_json_key"
+  | "models_json_command";
+
+export interface WebProviderAuthSummary {
+  readonly id: string;
+  readonly name: string;
+  readonly authMethods: readonly ("api_key" | "oauth")[];
+  readonly configured: boolean;
+  readonly source?: WebProviderAuthSource;
+  readonly subscription: boolean;
+  readonly nameTruncated: boolean;
+}
+
+export interface WebProviderAuthProjection {
+  readonly providers: readonly WebProviderAuthSummary[];
+  readonly truncation: {
+    readonly truncated: boolean;
+    readonly providersOmitted: number;
+    readonly namesTruncated: number;
+    readonly maxProviders: number;
+  };
+}
+
 export interface WebRuntimeEvent {
   type: string;
   detail?: Record<string, unknown>;
@@ -61,6 +89,7 @@ export interface WebRuntimeController {
   ): Promise<WebSessionCreationResult>;
   switchSession(sessionPath: string): Promise<{ cancelled: boolean }>;
   listModels(): WebModelSummary[];
+  listProviderAuth?(): WebProviderAuthProjection;
   setModel(
     provider: string,
     modelId: string,