perf(app): reduce startup websocket work

Make provider catalogs compact and content-addressed so repeat launches can reuse the persisted snapshot instead of transferring it again. Remove eager global catalog loading and the stopped-agent defensive tail fetch, while keeping sequence-gap and reconnect recovery as the correctness paths. Add an opt-in production-ID Android profiling build for local startup traces.

packages/app/app.config.js

@@ -1,9 +1,11 @@
 const fs = require("node:fs");
 const path = require("node:path");
 const pkg = require("./package.json");
+const withAndroidProfileable = require("./plugins/with-android-profileable");
 const withFdroidAutolinking = require("./plugins/with-fdroid-autolinking");
 const appVariant = process.env.APP_VARIANT ?? "production";
 const isFdroidBuild = process.env.PASEO_FDROID_BUILD === "1";
+const isProfileBuild = process.env.PASEO_PROFILE_BUILD === "1";
 
 const buildProfile = isFdroidBuild
   ? {
@@ -193,6 +195,7 @@ export default {
         },
       ],
       ...buildProfile.fdroidPlugins,
+      ...(isProfileBuild ? [withAndroidProfileable] : []),
     ],
     experiments: {
       typedRoutes: true,
@@ -201,6 +204,7 @@ export default {
     },
     extra: {
       fdroidBuild: isFdroidBuild,
+      profileBuild: isProfileBuild,
       router: {},
       eas: {
         projectId: "0e7f65ce-0367-46c8-a238-2b65963d235a",

packages/app/e2e/browser/agent-message-submission.spec.ts

@@ -915,39 +915,6 @@ test.describe("Agent message submission", () => {
     }
   });
 
-  test("reconciles an interrupted submission when live acknowledgements are missed", async ({
-    page,
-  }) => {
-    const gate = await installDaemonWebSocketGate(page);
-    const title = "Missed submission acknowledgements";
-    const prompt = "Interrupt without delivering live acknowledgements.";
-    const agent = await seedMockAgentWorkspace({
-      repoPrefix: "submission-missed-acknowledgements-",
-      title,
-      model: "one-minute-stream",
-    });
-    try {
-      await openAgentRoute(page, agent);
-      await expectComposerVisible(page);
-      gate.setAgentStreamItemSuppressed("user_message", true);
-      gate.setAgentStreamEventSuppressed("turn_canceled", true);
-
-      await submitMessage(page, prompt);
-      await gate.waitForAgentStreamItem("user_message");
-      await expectRunningAgentChrome(page, title);
-      await cancelAgent(page);
-      await gate.waitForAgentStreamEvent("turn_canceled");
-      await agent.client.waitForFinish(agent.agentId, 30_000);
-
-      await expect(page.getByTestId("user-message").filter({ hasText: prompt })).toHaveCount(1);
-      await expectAgentSurfacesIdle(page, title);
-    } finally {
-      gate.setAgentStreamItemSuppressed("user_message", false);
-      gate.setAgentStreamEventSuppressed("turn_canceled", false);
-      await agent.cleanup();
-    }
-  });
-
   test("keeps layout stable when submitting to an agent with existing history", async ({
     page,
     submissionScenario,

packages/app/modules/paseo-native-trace/android/build.gradle

@@ -0,0 +1,15 @@
+apply plugin: 'com.android.library'
+
+group = 'sh.paseo.trace'
+version = '0.1.0'
+
+def expoModulesCorePlugin = new File(project(":expo-modules-core").projectDir.absolutePath, "ExpoModulesCorePlugin.gradle")
+apply from: expoModulesCorePlugin
+applyKotlinExpoModulesCorePlugin()
+useCoreDependencies()
+useExpoPublishing()
+useDefaultAndroidSdkVersions()
+
+android {
+  namespace "sh.paseo.trace"
+}

packages/app/modules/paseo-native-trace/android/src/main/AndroidManifest.xml

@@ -0,0 +1 @@
+<manifest xmlns:android="http://schemas.android.com/apk/res/android" />

packages/app/modules/paseo-native-trace/android/src/main/java/sh/paseo/trace/PaseoNativeTraceModule.kt

@@ -0,0 +1,19 @@
+package sh.paseo.trace
+
+import android.os.Trace
+import expo.modules.kotlin.modules.Module
+import expo.modules.kotlin.modules.ModuleDefinition
+
+class PaseoNativeTraceModule : Module() {
+  override fun definition() = ModuleDefinition {
+    Name("PaseoNativeTrace")
+
+    Function("beginSection") { name: String ->
+      Trace.beginSection(name.take(127))
+    }
+
+    Function("endSection") {
+      Trace.endSection()
+    }
+  }
+}

packages/app/modules/paseo-native-trace/expo-module.config.json

@@ -0,0 +1,6 @@
+{
+  "platforms": ["android"],
+  "android": {
+    "modules": ["sh.paseo.trace.PaseoNativeTraceModule"]
+  }
+}

packages/app/modules/paseo-native-trace/package.json

@@ -0,0 +1,5 @@
+{
+  "name": "paseo-native-trace",
+  "version": "0.1.0",
+  "private": true
+}

packages/app/plugins/with-android-profileable.js

@@ -0,0 +1,15 @@
+const { withAndroidManifest } = require("expo/config-plugins");
+
+function withAndroidProfileable(config) {
+  return withAndroidManifest(config, (modConfig) => {
+    const application = modConfig.modResults.manifest.application?.[0];
+    if (!application) {
+      throw new Error("Could not enable Android profiling without an application manifest entry");
+    }
+
+    application.profileable = [{ $: { "android:shell": "true" } }];
+    return modConfig;
+  });
+}
+
+module.exports = withAndroidProfileable;

packages/app/src/constants/build-profile.ts

@@ -2,3 +2,6 @@ import Constants from "expo-constants";
 
 /** F-Droid build without proprietary camera or notification dependencies. */
 export const isFdroidBuild = Constants.expoConfig?.extra?.fdroidBuild === true;
+
+/** Production-like Android build with local profiling enabled. */
+export const isProfileBuild = Constants.expoConfig?.extra?.profileBuild === true;

packages/app/src/contexts/session-context.tsx

@@ -10,7 +10,6 @@ import {
   createSetAgentInitializing,
   refreshAgentInitializationTimeout,
 } from "@/hooks/use-agent-initialization";
-import { prefetchProvidersSnapshot } from "@/hooks/use-providers-snapshot";
 import { generateMessageId, type StreamItem } from "@/types/stream";
 import {
   createSessionAgentStreamReducerQueue,
@@ -494,19 +493,6 @@ function SessionProviderInternal({ children, serverId, client }: SessionProvider
     });
   }, [client, serverId, updateSessionServerInfo]);
 
-  useEffect(() => {
-    if (!isConnected) {
-      return;
-    }
-
-    const serverInfo = client.getLastServerInfoMessage();
-    if (!serverInfo?.features?.providersSnapshot) {
-      return;
-    }
-
-    prefetchProvidersSnapshot(serverId, client);
-  }, [client, isConnected, serverId]);
-
   useEffect(() => {
     const unregister = voiceRuntime?.registerSession({
       serverId,
@@ -739,19 +725,6 @@ function SessionProviderInternal({ children, serverId, client }: SessionProvider
     viewedTimelineSyncRef.current?.setConnected(isConnected);
   }, [isConnected]);
 
-  useEffect(
-    () =>
-      getHostRuntimeStore().subscribeAgentStoppedRunning(serverId, (agentId) => {
-        const session = useSessionStore.getState().sessions[serverId];
-        const timeline = selectAgentTimelineState(session, agentId);
-        if (timeline.status === "synced" && timeline.newer === "available") {
-          return;
-        }
-        viewedTimelineSyncRef.current?.reconcileAgent(agentId);
-      }),
-    [serverId],
-  );
-
   // Daemon message handlers - directly update Zustand store
   useEffect(() => {
     const agentStreamReducerQueue = createSessionAgentStreamReducerQueue({

packages/app/src/data/provider-snapshot-cache.test.ts

@@ -0,0 +1,65 @@
+import { describe, expect, it } from "vitest";
+import type { ProviderSnapshotEntry } from "@getpaseo/protocol/agent-types";
+import { compactProviderSnapshot } from "@getpaseo/protocol/provider-snapshot-codec";
+import { createProviderSnapshotCache } from "./provider-snapshot-cache";
+
+function createStorage() {
+  const values = new Map<string, string>();
+  return {
+    values,
+    async getItem(key: string) {
+      return values.get(key) ?? null;
+    },
+    async setItem(key: string, value: string) {
+      values.set(key, value);
+    },
+    async removeItem(key: string) {
+      values.delete(key);
+    },
+  };
+}
+
+describe("provider snapshot cache", () => {
+  it("round-trips compact snapshots with shared thinking option references", async () => {
+    const thinkingOptions = [{ id: "high", label: "High", isDefault: true }];
+    const entries: ProviderSnapshotEntry[] = [
+      {
+        provider: "pi",
+        status: "ready",
+        enabled: true,
+        models: ["one", "two"].map((id) => ({
+          provider: "pi",
+          id,
+          label: id,
+          thinkingOptions,
+          defaultThinkingOptionId: "high",
+        })),
+      },
+    ];
+    const storage = createStorage();
+    const cache = createProviderSnapshotCache(storage);
+
+    await cache.write({
+      serverId: "server-1",
+      cwd: "/repo",
+      hash: "snapshot-hash",
+      generatedAt: "2026-08-04T00:00:00.000Z",
+      compactSnapshot: compactProviderSnapshot(entries),
+    });
+    const cached = await cache.read("server-1", "/repo");
+
+    expect(cached?.entries).toEqual(entries);
+    expect(cached?.entries[0]?.models?.[0]?.thinkingOptions).toBe(
+      cached?.entries[0]?.models?.[1]?.thinkingOptions,
+    );
+  });
+
+  it("discards an invalid cache record", async () => {
+    const storage = createStorage();
+    const cache = createProviderSnapshotCache(storage);
+    storage.values.set('@paseo/provider-snapshot/v1:["server-1","/repo"]', "not json");
+
+    await expect(cache.read("server-1", "/repo")).resolves.toBeNull();
+    expect(storage.values.size).toBe(0);
+  });
+});

packages/app/src/data/provider-snapshot-cache.ts

@@ -0,0 +1,129 @@
+import AsyncStorage from "@react-native-async-storage/async-storage";
+import type { ProviderSnapshotEntry } from "@getpaseo/protocol/agent-types";
+import {
+  expandProviderSnapshot,
+  type CompactProviderSnapshot,
+} from "@getpaseo/protocol/provider-snapshot-codec";
+import { CompactProviderSnapshotSchema } from "@getpaseo/protocol/messages";
+
+const CACHE_VERSION = 1;
+const CACHE_KEY_PREFIX = "@paseo/provider-snapshot/v1";
+
+interface ProviderSnapshotStorage {
+  getItem(key: string): Promise<string | null>;
+  setItem(key: string, value: string): Promise<void>;
+  removeItem(key: string): Promise<void>;
+}
+
+interface StoredProviderSnapshot {
+  version: typeof CACHE_VERSION;
+  hash: string;
+  generatedAt: string;
+  compactSnapshot: CompactProviderSnapshot;
+}
+
+export interface CachedProviderSnapshot extends StoredProviderSnapshot {
+  entries: ProviderSnapshotEntry[];
+}
+
+export interface ProviderSnapshotCache {
+  read(serverId: string, cwd: string | null): Promise<CachedProviderSnapshot | null>;
+  write(input: {
+    serverId: string;
+    cwd: string | null;
+    hash: string;
+    generatedAt: string;
+    compactSnapshot: CompactProviderSnapshot;
+  }): Promise<void>;
+}
+
+export class ProviderSnapshotCacheMissError extends Error {
+  constructor() {
+    super("Daemon returned not-modified without a cached provider snapshot");
+    this.name = "ProviderSnapshotCacheMissError";
+  }
+}
+
+function cacheKey(serverId: string, cwd: string | null): string {
+  return `${CACHE_KEY_PREFIX}:${JSON.stringify([serverId, cwd])}`;
+}
+
+function parseStoredProviderSnapshot(value: string): StoredProviderSnapshot | null {
+  const parsed: unknown = JSON.parse(value);
+  if (typeof parsed !== "object" || parsed === null) return null;
+  const version = Reflect.get(parsed, "version");
+  const hash = Reflect.get(parsed, "hash");
+  const generatedAt = Reflect.get(parsed, "generatedAt");
+  const compactSnapshot = CompactProviderSnapshotSchema.safeParse(
+    Reflect.get(parsed, "compactSnapshot"),
+  );
+  if (
+    version !== CACHE_VERSION ||
+    typeof hash !== "string" ||
+    typeof generatedAt !== "string" ||
+    !compactSnapshot.success
+  ) {
+    return null;
+  }
+  return {
+    version,
+    hash,
+    generatedAt,
+    compactSnapshot: compactSnapshot.data,
+  };
+}
+
+async function discardCachedSnapshot(storage: ProviderSnapshotStorage, key: string): Promise<void> {
+  try {
+    await storage.removeItem(key);
+  } catch (error) {
+    if (!(error instanceof Error)) throw error;
+  }
+}
+
+export function createProviderSnapshotCache(
+  storage: ProviderSnapshotStorage,
+): ProviderSnapshotCache {
+  return {
+    async read(serverId, cwd) {
+      const key = cacheKey(serverId, cwd);
+      let value: string | null;
+      try {
+        value = await storage.getItem(key);
+      } catch (error) {
+        if (error instanceof Error) return null;
+        throw error;
+      }
+      if (value === null) return null;
+      try {
+        const stored = parseStoredProviderSnapshot(value);
+        if (!stored) {
+          await discardCachedSnapshot(storage, key);
+          return null;
+        }
+        return { ...stored, entries: expandProviderSnapshot(stored.compactSnapshot) };
+      } catch (error) {
+        if (!(error instanceof SyntaxError) && !(error instanceof RangeError)) {
+          throw error;
+        }
+        await discardCachedSnapshot(storage, key);
+        return null;
+      }
+    },
+    async write(input) {
+      const stored: StoredProviderSnapshot = {
+        version: CACHE_VERSION,
+        hash: input.hash,
+        generatedAt: input.generatedAt,
+        compactSnapshot: input.compactSnapshot,
+      };
+      try {
+        await storage.setItem(cacheKey(input.serverId, input.cwd), JSON.stringify(stored));
+      } catch (error) {
+        if (!(error instanceof Error)) throw error;
+      }
+    },
+  };
+}
+
+export const providerSnapshotCache = createProviderSnapshotCache(AsyncStorage);

packages/app/src/data/providers-snapshot.ts

@@ -21,11 +21,13 @@ export function providersSnapshotQueryKey(serverId: string | null, cwd?: string
 export function providersSnapshotRequestOptions(input: {
   cwd?: string | null;
   providers?: AgentProvider[];
+  ifNoneMatch?: string;
 }) {
   const normalizedCwd = normalizeProvidersSnapshotCwd(input.cwd);
   return {
     ...(normalizedCwd ? { cwd: normalizedCwd } : {}),
     ...(input.providers ? { providers: input.providers } : {}),
+    ...(input.ifNoneMatch ? { ifNoneMatch: input.ifNoneMatch } : {}),
   };
 }
 

packages/app/src/data/push-router.ts

@@ -8,7 +8,12 @@ import { agentCommandsQueryRoot } from "@/hooks/agent-commands-query";
 import { orderCheckoutDiffFiles } from "@/git/diff-order";
 import { daemonConfigQueryKey } from "@/data/daemon-config";
 import { daemonPairingOfferQueryKey } from "@/data/daemon-pairing";
-import { providersSnapshotQueryKey, providersSnapshotQueryRoot } from "@/data/providers-snapshot";
+import { providerSnapshotCache, type ProviderSnapshotCache } from "@/data/provider-snapshot-cache";
+import {
+  normalizeProvidersSnapshotCwd,
+  providersSnapshotQueryKey,
+  providersSnapshotQueryRoot,
+} from "@/data/providers-snapshot";
 
 type ProvidersSnapshotUpdateMessage = Extract<
   SessionOutboundMessage,
@@ -184,6 +189,7 @@ export function applyProvidersSnapshotUpdate(input: {
   serverId: string;
   queryClient: QueryClient;
   message: ProvidersSnapshotUpdate;
+  cache?: ProviderSnapshotCache;
 }): void {
   if (input.message.type !== "providers_snapshot_update") {
     return;
@@ -194,6 +200,16 @@ export function applyProvidersSnapshotUpdate(input: {
     generatedAt: input.message.payload.generatedAt,
     requestId: "providers_snapshot_update",
   });
+  const { compactSnapshot, snapshotHash } = input.message.payload;
+  if (compactSnapshot && snapshotHash) {
+    void (input.cache ?? providerSnapshotCache).write({
+      serverId: input.serverId,
+      cwd: normalizeProvidersSnapshotCwd(input.message.payload.cwd),
+      hash: snapshotHash,
+      generatedAt: input.message.payload.generatedAt,
+      compactSnapshot,
+    });
+  }
   void input.queryClient.invalidateQueries({
     queryKey: agentCommandsQueryRoot(input.serverId),
     exact: false,

packages/app/src/hooks/use-providers-snapshot.test.ts

@@ -3,6 +3,8 @@ import { beforeEach, describe, expect, it } from "vitest";
 
 import type { DaemonClient } from "@getpaseo/client/internal/daemon-client";
 import type { ProviderSnapshotEntry } from "@getpaseo/protocol/agent-types";
+import { compactProviderSnapshot } from "@getpaseo/protocol/provider-snapshot-codec";
+import type { CachedProviderSnapshot, ProviderSnapshotCache } from "@/data/provider-snapshot-cache";
 import { draftAgentCommandsQueryKey } from "@/hooks/agent-commands-query";
 import { applyProvidersSnapshotUpdate, type ProvidersSnapshotUpdate } from "@/data/push-router";
 import {
@@ -79,6 +81,21 @@ function codexEntry(
 const readyCodexModel = { provider: "codex", id: "gpt-5.4", label: "GPT-5.4" } as const;
 const serverId = "server-1";
 
+function createCache(initial: CachedProviderSnapshot | null = null): ProviderSnapshotCache & {
+  writes: Parameters<ProviderSnapshotCache["write"]>[0][];
+} {
+  const writes: Parameters<ProviderSnapshotCache["write"]>[0][] = [];
+  return {
+    writes,
+    async read() {
+      return initial;
+    },
+    async write(input) {
+      writes.push(input);
+    },
+  };
+}
+
 describe("providersSnapshotQueryKey", () => {
   it("uses separate keys for home and workspace scopes", () => {
     expect(providersSnapshotQueryKey(serverId)).toEqual(["providersSnapshot", serverId, "home"]);
@@ -95,7 +112,7 @@ describe("fetchProvidersSnapshot", () => {
   it("sends no cwd for the home scope", async () => {
     const client = createClient({ snapshots: [providersSnapshot([])] });
 
-    await fetchProvidersSnapshot({ client, cwd: null });
+    await fetchProvidersSnapshot({ client, serverId, cwd: null, cache: createCache() });
 
     expect(client.getCalls).toEqual([{}]);
   });
@@ -103,10 +120,78 @@ describe("fetchProvidersSnapshot", () => {
   it("sends the workspace cwd for the workspace scope", async () => {
     const client = createClient({ snapshots: [providersSnapshot([])] });
 
-    await fetchProvidersSnapshot({ client, cwd: "/repo-a" });
+    await fetchProvidersSnapshot({
+      client,
+      serverId,
+      cwd: "/repo-a",
+      cache: createCache(),
+    });
 
     expect(client.getCalls).toEqual([{ cwd: "/repo-a" }]);
   });
+
+  it("reuses a cached snapshot when the daemon reports its hash unchanged", async () => {
+    const entries = [codexEntry("ready", [readyCodexModel])];
+    const compactSnapshot = compactProviderSnapshot(entries);
+    const cache = createCache({
+      version: 1,
+      hash: "snapshot-hash",
+      generatedAt: "2026-01-01T00:00:00.000Z",
+      compactSnapshot,
+      entries,
+    });
+    const client = createClient({
+      snapshots: [
+        {
+          entries: [],
+          snapshotHash: "snapshot-hash",
+          notModified: true,
+          generatedAt: "2026-01-02T00:00:00.000Z",
+          requestId: "snapshot-2",
+        },
+      ],
+    });
+
+    const snapshot = await fetchProvidersSnapshot({
+      client,
+      serverId,
+      cwd: "/repo-a",
+      cache,
+    });
+
+    expect(client.getCalls).toEqual([{ cwd: "/repo-a", ifNoneMatch: "snapshot-hash" }]);
+    expect(snapshot.entries).toBe(entries);
+    expect(cache.writes).toEqual([]);
+  });
+
+  it("persists a changed compact snapshot for the next launch", async () => {
+    const entries = [codexEntry("ready", [readyCodexModel])];
+    const compactSnapshot = compactProviderSnapshot(entries);
+    const cache = createCache();
+    const client = createClient({
+      snapshots: [
+        {
+          entries,
+          compactSnapshot,
+          snapshotHash: "next-hash",
+          generatedAt: "2026-01-02T00:00:00.000Z",
+          requestId: "snapshot-2",
+        },
+      ],
+    });
+
+    await fetchProvidersSnapshot({ client, serverId, cwd: "/repo-a", cache });
+
+    expect(cache.writes).toEqual([
+      {
+        serverId,
+        cwd: "/repo-a",
+        hash: "next-hash",
+        generatedAt: "2026-01-02T00:00:00.000Z",
+        compactSnapshot,
+      },
+    ]);
+  });
 });
 
 describe("refreshAndApplyProvidersSnapshot", () => {
@@ -127,6 +212,7 @@ describe("refreshAndApplyProvidersSnapshot", () => {
       serverId,
       cwd: null,
       providers: ["codex"],
+      cache: createCache(),
     });
 
     expect(client.refreshCalls).toEqual([{ providers: ["codex"] }]);
@@ -147,6 +233,7 @@ describe("refreshAndApplyProvidersSnapshot", () => {
       serverId,
       cwd: "/repo-a",
       providers: ["codex"],
+      cache: createCache(),
     });
 
     expect(client.refreshCalls).toEqual([{ cwd: "/repo-a", providers: ["codex"] }]);
@@ -166,6 +253,7 @@ describe("refreshAndApplyProvidersSnapshot", () => {
       queryClient,
       serverId,
       cwd: null,
+      cache: createCache(),
     });
 
     expect(
@@ -186,6 +274,7 @@ describe("refreshAndApplyProvidersSnapshot", () => {
       queryClient,
       serverId,
       cwd: "/repo-a",
+      cache: createCache(),
     });
 
     expect(queryClient.getQueryState(providersSnapshotQueryKey(serverId))?.isInvalidated).toBe(
@@ -209,6 +298,7 @@ describe("refreshAndApplyProvidersSnapshot", () => {
       queryClient,
       serverId,
       cwd: "/repo-a",
+      cache: createCache(),
     });
 
     expect(queryClient.getQueryState(commandsKey)?.isInvalidated).toBe(true);
@@ -266,6 +356,27 @@ describe("applyProvidersSnapshotUpdate", () => {
     );
   });
 
+  it("persists compact push updates", () => {
+    const entries = [codexEntry("ready", [readyCodexModel])];
+    const compactSnapshot = compactProviderSnapshot(entries);
+    const cache = createCache();
+    const message = updateMessage(entries, "/repo-a");
+    message.payload.compactSnapshot = compactSnapshot;
+    message.payload.snapshotHash = "push-hash";
+
+    applyProvidersSnapshotUpdate({ serverId, queryClient, message, cache });
+
+    expect(cache.writes).toEqual([
+      {
+        serverId,
+        cwd: "/repo-a",
+        hash: "push-hash",
+        generatedAt: "2026-01-01T00:00:01.000Z",
+        compactSnapshot,
+      },
+    ]);
+  });
+
   it("applies Windows daemon updates to app-normalized workspace paths", () => {
     const workspaceCwd = "C:/Users/Ezekiel Bulver/project";
     const daemonCwd = "C:\\Users\\Ezekiel Bulver\\project";

packages/app/src/hooks/use-providers-snapshot.ts

@@ -8,6 +8,11 @@ import { useHostRuntimeClient, useHostRuntimeIsConnected } from "@/runtime/host-
 import { useSessionStore } from "@/stores/session-store";
 import { useReplicaQuery } from "@/data/query";
 import { queryClient as singletonQueryClient } from "@/data/query-client";
+import {
+  providerSnapshotCache,
+  ProviderSnapshotCacheMissError,
+  type ProviderSnapshotCache,
+} from "@/data/provider-snapshot-cache";
 import { agentCommandsQueryRoot } from "@/hooks/agent-commands-query";
 import {
   isProvidersSnapshotHomeScope,
@@ -29,9 +34,31 @@ export type ProvidersSnapshotClient = Pick<
 
 export async function fetchProvidersSnapshot(input: {
   client: ProvidersSnapshotClient;
+  serverId: string;
   cwd: string | null;
+  cache?: ProviderSnapshotCache;
 }): Promise<GetProvidersSnapshotResult> {
-  return input.client.getProvidersSnapshot(providersSnapshotRequestOptions({ cwd: input.cwd }));
+  const cache = input.cache ?? providerSnapshotCache;
+  const cached = await cache.read(input.serverId, input.cwd);
+  const snapshot = await input.client.getProvidersSnapshot(
+    providersSnapshotRequestOptions({ cwd: input.cwd, ifNoneMatch: cached?.hash }),
+  );
+  if (snapshot.notModified) {
+    if (!cached) {
+      throw new ProviderSnapshotCacheMissError();
+    }
+    return { ...snapshot, entries: cached.entries };
+  }
+  if (snapshot.compactSnapshot && snapshot.snapshotHash) {
+    await cache.write({
+      serverId: input.serverId,
+      cwd: input.cwd,
+      hash: snapshot.snapshotHash,
+      generatedAt: snapshot.generatedAt,
+      compactSnapshot: snapshot.compactSnapshot,
+    });
+  }
+  return snapshot;
 }
 
 export async function refreshAndApplyProvidersSnapshot(input: {
@@ -40,11 +67,17 @@ export async function refreshAndApplyProvidersSnapshot(input: {
   serverId: string;
   cwd: string | null;
   providers?: AgentProvider[];
+  cache?: ProviderSnapshotCache;
 }): Promise<RefreshProvidersSnapshotResult> {
   const refreshResult = await input.client.refreshProvidersSnapshot(
     providersSnapshotRequestOptions({ cwd: input.cwd, providers: input.providers }),
   );
-  const snapshot = await fetchProvidersSnapshot({ client: input.client, cwd: input.cwd });
+  const snapshot = await fetchProvidersSnapshot({
+    client: input.client,
+    serverId: input.serverId,
+    cwd: input.cwd,
+    cache: input.cache,
+  });
   input.queryClient.setQueryData(providersSnapshotQueryKey(input.serverId, input.cwd), snapshot);
   void input.queryClient.invalidateQueries({
     queryKey: agentCommandsQueryRoot(input.serverId),
@@ -113,10 +146,10 @@ export function useProvidersSnapshot(
     enabled: Boolean(enabled && supportsSnapshot && serverId && client && isConnected),
     pushEvent: "providers_snapshot_update",
     queryFn: async () => {
-      if (!client) {
+      if (!client || !serverId) {
         throw new Error(t("workspace.terminal.hostDisconnected"));
       }
-      return fetchProvidersSnapshot({ client, cwd });
+      return fetchProvidersSnapshot({ client, serverId, cwd });
     },
   });
 
@@ -180,6 +213,6 @@ export function prefetchProvidersSnapshot(
   void singletonQueryClient.prefetchQuery({
     queryKey,
     staleTime: Infinity,
-    queryFn: () => fetchProvidersSnapshot({ client, cwd }),
+    queryFn: () => fetchProvidersSnapshot({ client, serverId, cwd }),
   });
 }

packages/app/src/performance/native-trace.ts

@@ -0,0 +1,38 @@
+import type { DaemonClientTrace } from "@getpaseo/client/internal/daemon-client";
+import { requireOptionalNativeModule } from "expo-modules-core";
+import { isProfileBuild } from "@/constants/build-profile";
+
+interface PaseoNativeTraceModule {
+  beginSection(name: string): void;
+  endSection(): void;
+}
+
+const traceModule = requireOptionalNativeModule<PaseoNativeTraceModule>("PaseoNativeTrace");
+
+export const nativePerformanceTrace: DaemonClientTrace = {
+  isEnabled() {
+    return isProfileBuild && traceModule !== null;
+  },
+  beginSection(name, args) {
+    traceModule?.beginSection(formatSectionName(name, args));
+  },
+  endSection() {
+    traceModule?.endSection();
+  },
+};
+
+function formatSectionName(name: string, args?: Record<string, string>): string {
+  if (!args) {
+    return name;
+  }
+  const fields = Object.entries(args).map(([key, value]) => `${key}=${value}`);
+  return `${name}|${fields.join(";")}`;
+}
+
+export function traceInstant(name: string, args?: Record<string, string>): void {
+  if (!nativePerformanceTrace.isEnabled()) {
+    return;
+  }
+  nativePerformanceTrace.beginSection(name, args);
+  nativePerformanceTrace.endSection();
+}

packages/app/src/runtime/host-runtime.ts

@@ -56,6 +56,7 @@ import { resolveComposerAttachmentSubmitFormat } from "@/composer/attachments/su
 import { encodeImages } from "@/utils/encode-images";
 import { DirectorySync, type RefreshAgentDirectoryResult } from "@/runtime/directory-sync";
 import { ReplicaCache } from "@/runtime/replica-cache";
+import { nativePerformanceTrace } from "@/performance/native-trace";
 
 export type HostRuntimeConnectionStatus = "idle" | "connecting" | "online" | "offline" | "error";
 export type HostRegistryStatus = "loading" | "ready";
@@ -483,6 +484,7 @@ function createDefaultDeps(): HostRuntimeControllerDeps {
         appVersion: resolveAppVersion() ?? undefined,
         runtimeGeneration,
         capabilities: appCapabilities,
+        trace: nativePerformanceTrace,
       };
       if (connection.type === "directSocket" || connection.type === "directPipe") {
         return new DaemonClient({
@@ -521,6 +523,7 @@ function createDefaultDeps(): HostRuntimeControllerDeps {
         ...(host.serverId ? { serverId: host.serverId } : {}),
         ...(timeoutMs !== undefined ? { timeoutMs } : {}),
         capabilities: appCapabilities,
+        trace: nativePerformanceTrace,
       }),
     getClientId: () => getOrCreateClientId(),
     mountClientHandlers: ({ client, host }) => {
@@ -1341,7 +1344,6 @@ interface AgentDirectoryRefreshInput {
 export class HostRuntimeStore {
   private controllers = new Map<string, HostRuntimeController>();
   private serverListeners = new Map<string, Set<() => void>>();
-  private agentStoppedRunningListeners = new Map<string, Set<(agentId: string) => void>>();
   private globalListeners = new Set<() => void>();
   private hostListListeners = new Set<() => void>();
   private version = 0;
@@ -1589,12 +1591,11 @@ export class HostRuntimeStore {
     rekeyMap(this.controllers, oldServerId, newServerId);
     rekeyMap(this.lastConnectionStatusByServer, oldServerId, newServerId);
     rekeyMap(this.directoryBootstrapInFlight, oldServerId, newServerId);
-    rekeyMap(this.agentStoppedRunningListeners, oldServerId, newServerId);
     this.replicaCache.reconcileServerId(oldServerId, newServerId);
     this.directorySyncByServer.get(oldServerId)?.dispose();
     this.directorySyncByServer.delete(oldServerId);
     const directory = new DirectorySync(newServerId, {
-      onAgentStoppedRunning: (agentId) => this.onAgentStoppedRunning(newServerId, agentId),
+      onAgentStoppedRunning: (agentId) => this.drainQueuedAgentMessage(newServerId, agentId),
       markAgentLoading: () => controller.markAgentDirectorySyncLoading(),
       markAgentReady: () => controller.markAgentDirectorySyncReady(),
       markAgentError: (error) => controller.markAgentDirectorySyncError(error),
@@ -1977,7 +1978,7 @@ export class HostRuntimeStore {
       this.directorySyncByServer.set(
         host.serverId,
         new DirectorySync(host.serverId, {
-          onAgentStoppedRunning: (agentId) => this.onAgentStoppedRunning(host.serverId, agentId),
+          onAgentStoppedRunning: (agentId) => this.drainQueuedAgentMessage(host.serverId, agentId),
           markAgentLoading: () => controller.markAgentDirectorySyncLoading(),
           markAgentReady: () => controller.markAgentDirectorySyncReady(),
           markAgentError: (error) => controller.markAgentDirectorySyncError(error),
@@ -2176,18 +2177,6 @@ export class HostRuntimeStore {
     };
   }
 
-  subscribeAgentStoppedRunning(serverId: string, listener: (agentId: string) => void): () => void {
-    const listeners = this.agentStoppedRunningListeners.get(serverId) ?? new Set();
-    listeners.add(listener);
-    this.agentStoppedRunningListeners.set(serverId, listeners);
-    return () => {
-      const current = this.agentStoppedRunningListeners.get(serverId);
-      if (!current) return;
-      current.delete(listener);
-      if (current.size === 0) this.agentStoppedRunningListeners.delete(serverId);
-    };
-  }
-
   subscribeAll(listener: () => void): () => void {
     this.globalListeners.add(listener);
     return () => {
@@ -2296,13 +2285,6 @@ export class HostRuntimeStore {
       listener();
     }
   }
-
-  private onAgentStoppedRunning(serverId: string, agentId: string): void {
-    this.drainQueuedAgentMessage(serverId, agentId);
-    for (const listener of this.agentStoppedRunningListeners.get(serverId) ?? []) {
-      listener(agentId);
-    }
-  }
 }
 
 let singletonHostRuntimeStore: HostRuntimeStore | null = null;

packages/app/src/screens/workspace/workspace-screen.tsx

@@ -74,6 +74,7 @@ import { ImportSessionSheet } from "@/components/import-session-sheet";
 import { useToast } from "@/contexts/toast-context";
 import { selectIsFileExplorerOpen, usePanelStore } from "@/stores/panel-store";
 import { type ExplorerCheckoutContext } from "@/stores/explorer-checkout-context";
+import { traceInstant } from "@/performance/native-trace";
 import { useSessionStore, type WorkspaceDescriptor } from "@/stores/session-store";
 import {
   collectAllTabs,
@@ -938,6 +939,12 @@ export const WorkspaceScreen = memo(function WorkspaceScreen({
   recoveryAgentId,
 }: WorkspaceScreenProps) {
   const navigationFocused = useIsFocused();
+  useEffect(() => {
+    traceInstant("paseo.workspace.mount", { serverId, workspaceId });
+    return () => {
+      traceInstant("paseo.workspace.unmount", { serverId, workspaceId });
+    };
+  }, [serverId, workspaceId]);
   return (
     <WorkspaceScreenContent
       serverId={serverId}

packages/app/src/timeline/viewed-timeline-sync.test.ts

@@ -190,39 +190,6 @@ test("a gap absorbed by a running tail is recovered after the tail completes", a
   await vi.waitFor(() => expect(world.sync.getAgentTimelineStatus("agent-a")).toBe("ready"));
 });
 
-test("an idle reconciliation waits for an in-flight tail and fetches a fresh snapshot", async () => {
-  const world = new TimelineWorld();
-  world.sync.setConnected(true);
-  world.sync.replaceVisibleAgentIds("workspace", ["agent-a"]);
-  const membership = await world.nextMembership();
-  membership.succeed();
-  const initialTail = await world.nextFetch("agent-a");
-
-  world.sync.reconcileAgent("agent-a");
-
-  world.expectNoPendingFetch();
-  initialTail.respond({ hasNewer: false });
-
-  const reconciliation = await world.nextFetch("agent-a");
-  expect(reconciliation.request).toEqual({
-    direction: "tail",
-    limit: 40,
-    projection: "projected",
-  });
-  reconciliation.respond({ hasNewer: false });
-  await vi.waitFor(() => expect(world.sync.getAgentTimelineStatus("agent-a")).toBe("ready"));
-});
-
-test("does not reconcile an agent outside the viewed membership", () => {
-  const world = new TimelineWorld();
-  world.sync.setConnected(true);
-
-  world.sync.reconcileAgent("agent-a");
-
-  world.expectNoPendingFetch();
-  world.expectNoPendingMembership();
-});
-
 test("unchanged visible-set publication does not cancel paged catch-up", async () => {
   const world = new TimelineWorld();
   world.sync.setConnected(true);

packages/app/src/timeline/viewed-timeline-sync.ts

@@ -33,7 +33,6 @@ export interface ViewedTimelineSync extends ViewedTimelineUiBridge {
   setActive(active: boolean): void;
   setConnected(connected: boolean): void;
   setDeliveryMode(mode: TimelineDeliveryMode): void;
-  reconcileAgent(agentId: string): void;
   recoverGap(agentId: string, cursor: { epoch: string; endSeq: number }): void;
   dispose(): void;
 }
@@ -451,15 +450,6 @@ export function createViewedTimelineSync(ports: ViewedTimelineSyncPorts): Viewed
       if (deliveryMode === "selective" && connected) void reconcileMembership();
       else if (connected) startAcknowledgedCatchUps();
     },
-    reconcileAgent(agentId) {
-      if (!isDesired(agentId)) return;
-      const request = planTimelineTailFetch();
-      if (catchUps.get(agentId)?.status === "running") {
-        pendingCatchUps.set(agentId, request);
-        return;
-      }
-      startCatchUp(agentId, { request, supersede: true });
-    },
     recoverGap(agentId, cursor) {
       if (!isDesired(agentId)) return;
       startCatchUp(agentId, {

packages/app/src/utils/test-daemon-connection.test.ts

@@ -134,6 +134,27 @@ describe("test-daemon-connection connectToDaemon", () => {
     expect(probe.createdConfigs()[0]?.password).toBe("shared-secret");
   });
 
+  it("passes performance tracing into the connected client", async () => {
+    const { connectToDaemon } = await import("./test-daemon-connection");
+    const trace = {
+      isEnabled: () => true,
+      beginSection: vi.fn(),
+      endSection: vi.fn(),
+    };
+    const result = await connectToDaemon(
+      {
+        id: "direct:lan:6767",
+        type: "directTcp",
+        endpoint: "lan:6767",
+      },
+      { trace },
+      probe.deps,
+    );
+    await result.client.close();
+
+    expect(probe.createdConfigs()[0]?.trace).toBe(trace);
+  });
+
   it("uses relay TLS from the stored connection", async () => {
     const { connectToDaemon } = await import("./test-daemon-connection");
     const tlsResult = await connectToDaemon(

packages/app/src/utils/test-daemon-connection.ts

@@ -97,7 +97,10 @@ export class DaemonConnectionTestError extends Error {
 export async function buildClientConfig(
   connection: HostConnection,
   serverId?: string,
-  options?: { capabilities?: DaemonClientConfig["capabilities"] },
+  options?: {
+    capabilities?: DaemonClientConfig["capabilities"];
+    trace?: DaemonClientConfig["trace"];
+  },
   deps: Pick<
     DaemonConnectionDependencies<DaemonProbeClient>,
     "getClientId" | "resolveAppVersion" | "createLocalTransportFactory" | "buildLocalTransportUrl"
@@ -112,6 +115,7 @@ export async function buildClientConfig(
     suppressSendErrors: true,
     reconnect: { enabled: false },
     ...(options?.capabilities ? { capabilities: options.capabilities } : {}),
+    ...(options?.trace ? { trace: options.trace } : {}),
     ...((connection.type === "directSocket" || connection.type === "directPipe") &&
     localTransportFactory
       ? { transportFactory: localTransportFactory }
@@ -224,6 +228,7 @@ interface ProbeOptions {
   serverId?: string;
   timeoutMs?: number;
   capabilities?: DaemonClientConfig["capabilities"];
+  trace?: DaemonClientConfig["trace"];
 }
 
 function resolveTimeout(connection: HostConnection, options?: ProbeOptions): number {

packages/client/src/compat/normalize-provider-models.ts

@@ -1,5 +1,6 @@
 import type { AgentModelDefinition, ProviderSnapshotEntry } from "@getpaseo/protocol/agent-types";
 import { normalizeAgentModelDefinition } from "@getpaseo/protocol/agent-types";
+import { expandProviderSnapshot } from "@getpaseo/protocol/provider-snapshot-codec";
 import type {
   GetProvidersSnapshotResponseMessage,
   ListProviderModelsResponseMessage,
@@ -59,7 +60,9 @@ export function normalizeListProviderModelsPayload(
 export function normalizeProvidersSnapshotPayload<
   T extends GetProvidersSnapshotPayload | ProvidersSnapshotUpdatePayload,
 >(payload: T): T {
-  const entries = normalizeProviderSnapshotEntries(payload.entries);
+  const entries = payload.compactSnapshot
+    ? expandProviderSnapshot(payload.compactSnapshot)
+    : normalizeProviderSnapshotEntries(payload.entries);
   return entries === payload.entries ? payload : { ...payload, entries };
 }
 

packages/client/src/daemon-client.test.ts

@@ -1,6 +1,11 @@
 import { afterEach, expect, expectTypeOf, test, vi } from "vitest";
 import { z } from "zod";
-import { DaemonClient, type DaemonTransport, type Logger } from "./daemon-client";
+import {
+  DaemonClient,
+  type DaemonClientTrace,
+  type DaemonTransport,
+  type Logger,
+} from "./daemon-client";
 import { CLIENT_CAPS } from "@getpaseo/protocol/client-capabilities";
 import { BROWSER_AUTOMATION_COMMAND_NAMES } from "@getpaseo/protocol/browser-automation/rpc-schemas";
 import {
@@ -34,6 +39,24 @@ function createMockLogger() {
   };
 }
 
+interface TraceRecord {
+  phase: "begin" | "end";
+  name?: string;
+  args?: Record<string, string>;
+}
+
+function createTraceRecorder(): { trace: DaemonClientTrace; records: TraceRecord[] } {
+  const records: TraceRecord[] = [];
+  return {
+    trace: {
+      isEnabled: () => true,
+      beginSection: (name, args) => records.push({ phase: "begin", name, args }),
+      endSection: () => records.push({ phase: "end" }),
+    },
+    records,
+  };
+}
+
 function createMockTransport() {
   const sent: Array<string | Uint8Array | ArrayBuffer> = [];
 
@@ -161,6 +184,56 @@ afterEach(async () => {
   vi.unstubAllGlobals();
 });
 
+test("traces WebSocket frames, message types, and JSON parse duration", async () => {
+  const mock = createMockTransport();
+  const recorder = createTraceRecorder();
+  const client = new DaemonClient({
+    url: "ws://test",
+    clientId: "trace_unit_test",
+    transportFactory: () => mock.transport,
+    reconnect: { enabled: false },
+    trace: recorder.trace,
+  });
+  clients.push(client);
+
+  const connectPromise = client.connect();
+  mock.triggerOpen({ preserveSent: true });
+  await connectPromise;
+
+  expect(recorder.records).toEqual([
+    {
+      phase: "begin",
+      name: "paseo.ws.message.outbound",
+      args: { envelopeType: "hello", messageType: "hello" },
+    },
+    { phase: "end" },
+    {
+      phase: "begin",
+      name: "paseo.ws.frame.outbound",
+      args: { kind: "text", size: expect.any(String) },
+    },
+    { phase: "end" },
+    {
+      phase: "begin",
+      name: "paseo.ws.frame.inbound",
+      args: { kind: "text", size: expect.any(String) },
+    },
+    {
+      phase: "begin",
+      name: "paseo.ws.json.parse",
+      args: { size: expect.any(String) },
+    },
+    { phase: "end" },
+    {
+      phase: "begin",
+      name: "paseo.ws.message.inbound",
+      args: { envelopeType: "session", messageType: "status" },
+    },
+    { phase: "end" },
+    { phase: "end" },
+  ]);
+});
+
 test("does not infer browser automation capabilities from Electron runtime", async () => {
   vi.stubGlobal("navigator", {
     userAgent:
@@ -664,6 +737,7 @@ test("advertises client capabilities in hello", async () => {
     clientType: "cli",
     protocolVersion: 1,
     capabilities: {
+      compact_provider_snapshots: true,
       custom_mode_icons: true,
       project_updates: true,
       provider_subagents: true,
@@ -4384,6 +4458,81 @@ test("lists available providers via RPC", async () => {
   });
 });
 
+test("requests provider snapshots conditionally and expands the compact response", async () => {
+  const mock = createMockTransport();
+  const client = new DaemonClient({
+    url: "ws://test",
+    clientId: "clsk_provider_snapshot_test",
+    reconnect: { enabled: false },
+    transportFactory: () => mock.transport,
+  });
+  clients.push(client);
+
+  const connectPromise = client.connect();
+  mock.triggerOpen();
+  await connectPromise;
+
+  const promise = client.getProvidersSnapshot({ cwd: "/repo", ifNoneMatch: "previous-hash" });
+  const request = parseSentFrame(mock.sent[0]);
+  expect(request).toMatchObject({
+    type: "get_providers_snapshot_request",
+    cwd: "/repo",
+    ifNoneMatch: "previous-hash",
+  });
+
+  mock.triggerMessage(
+    wrapSessionMessage({
+      type: "get_providers_snapshot_response",
+      payload: {
+        entries: [],
+        compactSnapshot: {
+          entries: [
+            {
+              provider: "pi",
+              status: "ready",
+              enabled: true,
+              models: [
+                { id: "model-a", label: "Model A", thinkingSet: 0 },
+                { id: "model-b", label: "Model B", thinkingSet: 0 },
+              ],
+            },
+          ],
+          thinkingSets: [
+            {
+              options: [{ id: "high", label: "High", isDefault: true }],
+              defaultOptionId: "high",
+            },
+          ],
+        },
+        snapshotHash: "next-hash",
+        generatedAt: "2026-08-04T00:00:00.000Z",
+        requestId: request.requestId,
+      },
+    }),
+  );
+
+  const response = await promise;
+  expect(response.entries[0]?.models).toEqual([
+    {
+      provider: "pi",
+      id: "model-a",
+      label: "Model A",
+      thinkingOptions: [{ id: "high", label: "High", isDefault: true }],
+      defaultThinkingOptionId: "high",
+    },
+    {
+      provider: "pi",
+      id: "model-b",
+      label: "Model B",
+      thinkingOptions: [{ id: "high", label: "High", isDefault: true }],
+      defaultThinkingOptionId: "high",
+    },
+  ]);
+  expect(response.entries[0]?.models?.[0]?.thinkingOptions).toBe(
+    response.entries[0]?.models?.[1]?.thinkingOptions,
+  );
+});
+
 test("lists commands with draft config via RPC", async () => {
   const logger = createMockLogger();
   const mock = createMockTransport();

packages/client/src/daemon-client.ts

@@ -317,9 +317,16 @@ export interface DaemonClientConfig {
   };
   runtimeMetricsIntervalMs?: number;
   runtimeMetricsWindowMs?: number;
+  trace?: DaemonClientTrace;
   capabilities?: Partial<Record<ClientCapability, unknown>>;
 }
 
+export interface DaemonClientTrace {
+  isEnabled(): boolean;
+  beginSection(name: string, args?: Record<string, string>): void;
+  endSection(): void;
+}
+
 export interface SendMessageOptions {
   messageId?: string;
   images?: Array<{ data: string; mimeType: string }>;
@@ -1035,6 +1042,26 @@ function concatByteChunks(chunks: Uint8Array[], size: number): Uint8Array {
   return bytes;
 }
 
+function getTransportFrameSize(frame: string | Uint8Array | ArrayBuffer): number {
+  if (typeof frame === "string") {
+    return frame.length;
+  }
+  return frame.byteLength;
+}
+
+function describeInboundTransportFrame(
+  frame: unknown,
+  rawBytes: Uint8Array | null,
+): Record<string, string> {
+  if (typeof frame === "string") {
+    return { kind: "text", size: String(frame.length) };
+  }
+  if (rawBytes) {
+    return { kind: "binary", size: String(rawBytes.byteLength) };
+  }
+  return { kind: "unknown", size: "0" };
+}
+
 function hashForLog(value: string): string {
   let hash = 0;
   for (let index = 0; index < value.length; index += 1) {
@@ -1535,6 +1562,49 @@ export class DaemonClient {
   // Core Send Helpers
   // ============================================================================
 
+  private beginTraceSection(name: string, args?: Record<string, string>): boolean {
+    const trace = this.config.trace;
+    if (!trace?.isEnabled()) {
+      return false;
+    }
+    trace.beginSection(name, args);
+    return true;
+  }
+
+  private endTraceSection(isOpen: boolean): void {
+    if (isOpen) {
+      this.config.trace?.endSection();
+    }
+  }
+
+  private traceInstant(name: string, args?: Record<string, string>): void {
+    const isOpen = this.beginTraceSection(name, args);
+    this.endTraceSection(isOpen);
+  }
+
+  private sendJsonMessage(envelopeType: string, messageType: string, message: unknown): void {
+    this.traceInstant("paseo.ws.message.outbound", {
+      envelopeType,
+      messageType,
+    });
+    this.sendTransportFrame(JSON.stringify(message));
+  }
+
+  private sendTransportFrame(frame: string | Uint8Array | ArrayBuffer): void {
+    if (!this.transport) {
+      throw new Error("Transport not connected");
+    }
+    const isOpen = this.beginTraceSection("paseo.ws.frame.outbound", {
+      kind: typeof frame === "string" ? "text" : "binary",
+      size: String(getTransportFrameSize(frame)),
+    });
+    try {
+      this.transport.send(frame);
+    } finally {
+      this.endTraceSection(isOpen);
+    }
+  }
+
   /**
    * Send a session message. For fire-and-forget messages (heartbeats, etc.),
    * failures are suppressed if `suppressSendErrors` is configured.
@@ -1549,7 +1619,7 @@ export class DaemonClient {
     }
     const payload = SessionInboundMessageSchema.parse(message);
     try {
-      this.transport.send(JSON.stringify({ type: "session", message: payload }));
+      this.sendJsonMessage("session", payload.type, { type: "session", message: payload });
     } catch (error) {
       if (this.config.suppressSendErrors) {
         return;
@@ -1566,7 +1636,11 @@ export class DaemonClient {
       throw new Error(`Transport not connected (status: ${this.connectionState.status})`);
     }
     try {
-      this.transport.send(frame);
+      this.traceInstant("paseo.ws.message.outbound", {
+        envelopeType: "binary",
+        messageType: "binary",
+      });
+      this.sendTransportFrame(frame);
     } catch (error) {
       if (this.config.suppressSendErrors) {
         return;
@@ -1587,7 +1661,7 @@ export class DaemonClient {
     // If connected, send immediately
     if (this.transport && status === "connected") {
       const payload = SessionInboundMessageSchema.parse(message);
-      this.transport.send(JSON.stringify({ type: "session", message: payload }));
+      this.sendJsonMessage("session", payload.type, { type: "session", message: payload });
       return Promise.resolve();
     }
 
@@ -1623,7 +1697,7 @@ export class DaemonClient {
       try {
         if (this.transport && this.connectionState.status === "connected") {
           const payload = SessionInboundMessageSchema.parse(pending.message);
-          this.transport.send(JSON.stringify({ type: "session", message: payload }));
+          this.sendJsonMessage("session", payload.type, { type: "session", message: payload });
           pending.resolve();
         } else {
           pending.reject(new Error("Connection lost before message could be sent"));
@@ -1777,7 +1851,7 @@ export class DaemonClient {
     }
     const payload = SessionInboundMessageSchema.parse(message);
     try {
-      this.transport.send(JSON.stringify({ type: "session", message: payload }));
+      this.sendJsonMessage("session", payload.type, { type: "session", message: payload });
     } catch (error) {
       throw error instanceof Error ? error : new Error(String(error));
     }
@@ -1952,7 +2026,7 @@ export class DaemonClient {
     this.pingProbe = probe;
 
     try {
-      this.transport.send(JSON.stringify({ type: "ping" }));
+      this.sendJsonMessage("ping", "ping", { type: "ping" });
     } catch (error) {
       this.clearPingProbe();
       const sendError = error instanceof Error ? error : new Error(String(error));
@@ -4421,6 +4495,7 @@ export class DaemonClient {
 
   async getProvidersSnapshot(options?: {
     cwd?: string;
+    ifNoneMatch?: string;
     requestId?: string;
   }): Promise<GetProvidersSnapshotPayload> {
     const payload = await this.sendCorrelatedSessionRequest({
@@ -4428,6 +4503,7 @@ export class DaemonClient {
       message: {
         type: "get_providers_snapshot_request",
         cwd: options?.cwd,
+        ifNoneMatch: options?.ifNoneMatch,
       },
       responseType: "get_providers_snapshot_response",
     });
@@ -5326,23 +5402,22 @@ export class DaemonClient {
     }
 
     try {
-      this.transport.send(
-        JSON.stringify({
-          type: "hello",
-          clientId: this.config.clientId,
-          clientType: this.config.clientType ?? "cli",
-          protocolVersion: 1,
-          capabilities: {
-            [CLIENT_CAPS.customModeIcons]: true,
-            [CLIENT_CAPS.reasoningMergeEnum]: true,
-            [CLIENT_CAPS.terminalReflowableSnapshot]: true,
-            [CLIENT_CAPS.providerSubagents]: true,
-            [CLIENT_CAPS.projectUpdates]: true,
-            ...this.config.capabilities,
-          },
-          ...(this.config.appVersion ? { appVersion: this.config.appVersion } : {}),
-        }),
-      );
+      this.sendJsonMessage("hello", "hello", {
+        type: "hello",
+        clientId: this.config.clientId,
+        clientType: this.config.clientType ?? "cli",
+        protocolVersion: 1,
+        capabilities: {
+          [CLIENT_CAPS.customModeIcons]: true,
+          [CLIENT_CAPS.reasoningMergeEnum]: true,
+          [CLIENT_CAPS.terminalReflowableSnapshot]: true,
+          [CLIENT_CAPS.providerSubagents]: true,
+          [CLIENT_CAPS.projectUpdates]: true,
+          [CLIENT_CAPS.compactProviderSnapshots]: true,
+          ...this.config.capabilities,
+        },
+        ...(this.config.appVersion ? { appVersion: this.config.appVersion } : {}),
+      });
     } catch (error) {
       const message = error instanceof Error ? error.message : "Failed to send hello message";
       this.lastErrorValue = message;
@@ -5413,24 +5488,37 @@ export class DaemonClient {
     }
 
     const rawBytes = asUint8Array(rawData);
-    if (rawBytes && this.tryHandleBinaryFrame(rawBytes)) {
-      return;
+    const isOpen = this.beginTraceSection(
+      "paseo.ws.frame.inbound",
+      describeInboundTransportFrame(rawData, rawBytes),
+    );
+    try {
+      if (rawBytes && this.tryHandleBinaryFrame(rawBytes)) {
+        return;
+      }
+      const payload = decodeMessageData(rawData);
+      if (!payload) {
+        return;
+      }
+      this.handleJsonPayload(payload, rawBytes?.byteLength);
+    } finally {
+      this.endTraceSection(isOpen);
     }
-    const payload = decodeMessageData(rawData);
-    if (!payload) {
-      return;
-    }
-    this.handleJsonPayload(payload, rawBytes?.byteLength);
   }
 
   private handleJsonPayload(payload: string, rawBytesLength: number | undefined): void {
     const bytes = rawBytesLength ?? payload.length;
     const startMs = perfNow();
     let parsedJson: unknown;
+    const parseTraceOpen = this.beginTraceSection("paseo.ws.json.parse", {
+      size: String(bytes),
+    });
     try {
       parsedJson = JSON.parse(payload);
     } catch {
       return;
+    } finally {
+      this.endTraceSection(parseTraceOpen);
     }
 
     const parsed = validateWSOutboundMessage(parsedJson);
@@ -5457,11 +5545,19 @@ export class DaemonClient {
     this.consecutiveLivenessFailures = 0;
 
     if (parsed.data.type === "pong") {
+      this.traceInstant("paseo.ws.message.inbound", {
+        envelopeType: "pong",
+        messageType: "pong",
+      });
       this.resolvePingProbe();
       this.runtimeMetrics?.recordMessage("pong", bytes, perfNow() - startMs);
       return;
     }
 
+    this.traceInstant("paseo.ws.message.inbound", {
+      envelopeType: "session",
+      messageType: parsed.data.message.type,
+    });
     this.handleSessionMessage(parsed.data.message);
     const msgType = parsed.data.message.type;
     this.runtimeMetrics?.recordMessage(msgType, bytes, perfNow() - startMs);
@@ -5473,6 +5569,11 @@ export class DaemonClient {
   private tryHandleBinaryFrame(rawBytes: Uint8Array): boolean {
     const fileFrame = decodeFileTransferFrame(rawBytes);
     if (fileFrame) {
+      this.traceInstant("paseo.ws.message.inbound", {
+        envelopeType: "binary",
+        messageType: "file",
+        opcode: String(fileFrame.opcode),
+      });
       this.consecutiveLivenessFailures = 0;
       this.handleFileTransferFrame(fileFrame);
       this.runtimeMetrics?.recordBinaryFrame("other", rawBytes.byteLength, 0);
@@ -5483,6 +5584,11 @@ export class DaemonClient {
     if (!frame) {
       return false;
     }
+    this.traceInstant("paseo.ws.message.inbound", {
+      envelopeType: "binary",
+      messageType: "terminal",
+      opcode: String(frame.opcode),
+    });
     this.consecutiveLivenessFailures = 0;
     const binaryStartMs = perfNow();
     this.terminalStreams.handleFrame(frame);

packages/protocol/src/client-capabilities.ts

@@ -20,6 +20,10 @@ export const CLIENT_CAPS = {
   providerSubagents: "provider_subagents",
   // COMPAT(projectUpdates): added in v0.1.109, remove gate after 2027-01-15.
   projectUpdates: "project_updates",
+  // COMPAT(compactProviderSnapshots): added in v0.2.X. Capable clients receive
+  // provider catalogs with shared thinking sets and may revalidate by content hash.
+  // Remove the legacy snapshot encoding after 2027-02-04.
+  compactProviderSnapshots: "compact_provider_snapshots",
   browserHost: "browser_host",
 } as const;
 

packages/protocol/src/messages.ts

@@ -256,7 +256,7 @@ export const AgentFeatureSchema = z.discriminatedUnion("type", [
   AgentFeatureSelectSchema,
 ]);
 
-const AgentModelDefinitionSchema: z.ZodType<AgentModelDefinition> = z.object({
+const AgentModelDefinitionSchema = z.object({
   provider: AgentProviderSchema,
   id: z.string(),
   label: z.string(),
@@ -266,7 +266,7 @@ const AgentModelDefinitionSchema: z.ZodType<AgentModelDefinition> = z.object({
   contextWindowMaxTokens: z.number().optional(),
   thinkingOptions: z.array(AgentSelectOptionSchema).optional(),
   defaultThinkingOptionId: z.string().optional(),
-});
+}) satisfies z.ZodType<AgentModelDefinition>;
 
 export const ProviderSnapshotEntrySchema = z.object({
   provider: AgentProviderSchema,
@@ -282,6 +282,29 @@ export const ProviderSnapshotEntrySchema = z.object({
   defaultModeId: z.string().nullable().optional(),
 });
 
+export const CompactProviderSnapshotModelSchema = AgentModelDefinitionSchema.omit({
+  provider: true,
+  thinkingOptions: true,
+}).extend({
+  thinkingSet: z.number().int().nonnegative().optional(),
+});
+
+export const ProviderSnapshotThinkingSetSchema = z.object({
+  options: z.array(AgentSelectOptionSchema),
+  defaultOptionId: z.string().optional(),
+});
+
+export const CompactProviderSnapshotEntrySchema = ProviderSnapshotEntrySchema.omit({
+  models: true,
+}).extend({
+  models: z.array(CompactProviderSnapshotModelSchema).optional(),
+});
+
+export const CompactProviderSnapshotSchema = z.object({
+  entries: z.array(CompactProviderSnapshotEntrySchema),
+  thinkingSets: z.array(ProviderSnapshotThinkingSetSchema),
+});
+
 const AgentCapabilityFlagsSchema: z.ZodType<AgentCapabilityFlags> = z
   .object({
     supportsStreaming: z.boolean(),
@@ -1326,6 +1349,8 @@ export const ListAvailableProvidersRequestMessageSchema = z.object({
 export const GetProvidersSnapshotRequestMessageSchema = z.object({
   type: z.literal("get_providers_snapshot_request"),
   cwd: z.string().optional(),
+  // COMPAT(compactProviderSnapshots): old daemons ignore this field and return a full snapshot.
+  ifNoneMatch: z.string().optional(),
   requestId: z.string(),
 });
 
@@ -4956,6 +4981,9 @@ export const GetProvidersSnapshotResponseMessageSchema = z.object({
   type: z.literal("get_providers_snapshot_response"),
   payload: z.object({
     entries: z.array(ProviderSnapshotEntrySchema),
+    compactSnapshot: CompactProviderSnapshotSchema.optional(),
+    snapshotHash: z.string().optional(),
+    notModified: z.boolean().optional(),
     generatedAt: z.string(),
     requestId: z.string(),
   }),
@@ -4967,6 +4995,8 @@ export const ProvidersSnapshotUpdateMessageSchema = z.object({
   payload: z.object({
     cwd: z.string().optional(),
     entries: z.array(ProviderSnapshotEntrySchema),
+    compactSnapshot: CompactProviderSnapshotSchema.optional(),
+    snapshotHash: z.string().optional(),
     generatedAt: z.string(),
   }),
 });
@@ -5938,6 +5968,7 @@ export const WSHelloMessageSchema = z.object({
       [CLIENT_CAPS.terminalReflowableSnapshot]: z.boolean().optional(),
       [CLIENT_CAPS.providerSubagents]: z.boolean().optional(),
       [CLIENT_CAPS.projectUpdates]: z.boolean().optional(),
+      [CLIENT_CAPS.compactProviderSnapshots]: z.boolean().optional(),
       [CLIENT_CAPS.browserHost]: BrowserAutomationHostCapabilitySchema.optional(),
     })
     .passthrough()

packages/protocol/src/provider-snapshot-codec.test.ts

@@ -0,0 +1,79 @@
+import { describe, expect, it } from "vitest";
+import type { ProviderSnapshotEntry } from "./agent-types.js";
+import { compactProviderSnapshot, expandProviderSnapshot } from "./provider-snapshot-codec.js";
+
+const sharedThinking = [
+  { id: "off", label: "Off", description: "No extra reasoning" },
+  { id: "minimal", label: "Minimal", description: "Light reasoning" },
+  { id: "low", label: "Low" },
+  { id: "medium", label: "Medium", description: "Balanced reasoning" },
+  { id: "high", label: "High", isDefault: true },
+  { id: "xhigh", label: "XHigh", description: "Very deep reasoning" },
+  { id: "max", label: "Max", description: "Extreme reasoning" },
+];
+
+function providerEntry(): ProviderSnapshotEntry {
+  return {
+    provider: "pi",
+    status: "ready",
+    enabled: true,
+    models: [
+      {
+        provider: "pi",
+        id: "openai/gpt-a",
+        label: "GPT A",
+        description: "openai/gpt-a",
+        metadata: { provider: "openai", modelId: "gpt-a" },
+        thinkingOptions: sharedThinking,
+        defaultThinkingOptionId: "high",
+      },
+      {
+        provider: "pi",
+        id: "openai/gpt-b",
+        label: "GPT B",
+        metadata: { provider: "openai", modelId: "gpt-b" },
+        thinkingOptions: structuredClone(sharedThinking),
+        defaultThinkingOptionId: "high",
+      },
+    ],
+    modes: [{ id: "build", label: "Build" }],
+  };
+}
+
+describe("provider snapshot codec", () => {
+  it("shares repeated thinking options while preserving the public snapshot shape", () => {
+    const original = [providerEntry()];
+    const compact = compactProviderSnapshot(original);
+    const expanded = expandProviderSnapshot(compact);
+
+    expect(compact.thinkingSets).toHaveLength(1);
+    expect(compact.entries[0]?.models?.map((model) => model.thinkingSet)).toEqual([0, 0]);
+    expect(expanded).toEqual(original);
+    expect(expanded[0]?.models?.[0]?.thinkingOptions).toBe(
+      expanded[0]?.models?.[1]?.thinkingOptions,
+    );
+  });
+
+  it("shrinks catalogs dominated by one repeated thinking set", () => {
+    const model = providerEntry().models?.[0];
+    if (!model) throw new Error("fixture model missing");
+    const entries: ProviderSnapshotEntry[] = [
+      {
+        provider: "pi",
+        status: "ready",
+        enabled: true,
+        models: Array.from({ length: 200 }, (_, index) => ({
+          ...model,
+          id: `openai/model-${index}`,
+          label: `Model ${index}`,
+          metadata: { provider: "openai", modelId: `model-${index}` },
+        })),
+      },
+    ];
+
+    const legacyBytes = JSON.stringify(entries).length;
+    const compactBytes = JSON.stringify(compactProviderSnapshot(entries)).length;
+
+    expect(compactBytes).toBeLessThan(legacyBytes * 0.5);
+  });
+});

packages/protocol/src/provider-snapshot-codec.ts

@@ -0,0 +1,119 @@
+import type {
+  AgentModelDefinition,
+  AgentSelectOption,
+  ProviderSnapshotEntry,
+} from "./agent-types.js";
+
+export interface CompactProviderSnapshotModel extends Omit<
+  AgentModelDefinition,
+  "provider" | "thinkingOptions"
+> {
+  thinkingSet?: number;
+}
+
+export interface CompactProviderSnapshotEntry extends Omit<ProviderSnapshotEntry, "models"> {
+  models?: CompactProviderSnapshotModel[];
+}
+
+export interface ProviderSnapshotThinkingSet {
+  options: AgentSelectOption[];
+  defaultOptionId?: string;
+}
+
+export interface CompactProviderSnapshot {
+  entries: CompactProviderSnapshotEntry[];
+  thinkingSets: ProviderSnapshotThinkingSet[];
+}
+
+function thinkingSetKey(set: ProviderSnapshotThinkingSet): string {
+  return JSON.stringify(set);
+}
+
+function compactModel(
+  {
+    provider: _provider,
+    thinkingOptions,
+    defaultThinkingOptionId,
+    ...modelFields
+  }: AgentModelDefinition,
+  thinkingSets: ProviderSnapshotThinkingSet[],
+  thinkingSetIndexes: Map<string, number>,
+): CompactProviderSnapshotModel {
+  const compact: CompactProviderSnapshotModel = modelFields;
+
+  if (thinkingOptions === undefined) {
+    if (defaultThinkingOptionId !== undefined) {
+      compact.defaultThinkingOptionId = defaultThinkingOptionId;
+    }
+    return compact;
+  }
+
+  const thinkingSet: ProviderSnapshotThinkingSet = {
+    options: thinkingOptions,
+    ...(defaultThinkingOptionId !== undefined ? { defaultOptionId: defaultThinkingOptionId } : {}),
+  };
+  const key = thinkingSetKey(thinkingSet);
+  const existingIndex = thinkingSetIndexes.get(key);
+  if (existingIndex !== undefined) {
+    compact.thinkingSet = existingIndex;
+    return compact;
+  }
+
+  const index = thinkingSets.length;
+  thinkingSets.push(thinkingSet);
+  thinkingSetIndexes.set(key, index);
+  compact.thinkingSet = index;
+  return compact;
+}
+
+export function compactProviderSnapshot(entries: ProviderSnapshotEntry[]): CompactProviderSnapshot {
+  const thinkingSets: ProviderSnapshotThinkingSet[] = [];
+  const thinkingSetIndexes = new Map<string, number>();
+  const compactEntries = entries.map((entry): CompactProviderSnapshotEntry => {
+    if (entry.models === undefined) {
+      return entry;
+    }
+    return {
+      ...entry,
+      models: entry.models.map((model) => compactModel(model, thinkingSets, thinkingSetIndexes)),
+    };
+  });
+  return { entries: compactEntries, thinkingSets };
+}
+
+function expandModel(
+  provider: string,
+  model: CompactProviderSnapshotModel,
+  thinkingSets: ProviderSnapshotThinkingSet[],
+): AgentModelDefinition {
+  const { thinkingSet: thinkingSetIndex, ...modelFields } = model;
+  if (thinkingSetIndex === undefined) {
+    return { provider, ...modelFields };
+  }
+
+  const thinkingSet = thinkingSets[thinkingSetIndex];
+  if (!thinkingSet) {
+    throw new RangeError(`Provider snapshot references missing thinking set ${thinkingSetIndex}`);
+  }
+  return {
+    provider,
+    ...modelFields,
+    thinkingOptions: thinkingSet.options,
+    ...(thinkingSet.defaultOptionId !== undefined
+      ? { defaultThinkingOptionId: thinkingSet.defaultOptionId }
+      : {}),
+  };
+}
+
+export function expandProviderSnapshot(snapshot: CompactProviderSnapshot): ProviderSnapshotEntry[] {
+  return snapshot.entries.map((entry): ProviderSnapshotEntry => {
+    const { models, ...entryFields } = entry;
+    if (models === undefined) return entryFields;
+    return {
+      ...entryFields,
+      models: models.map((model) =>
+        expandModel(entryFields.provider, model, snapshot.thinkingSets),
+      ),
+    };
+  });
+}

packages/protocol/tests/validation/ws-outbound.test.ts

@@ -138,6 +138,42 @@ const SourceSchema = z.object({
     );
   });
 
+  it("accepts a compact provider snapshot envelope", () => {
+    const envelope = {
+      type: "session",
+      message: {
+        type: "get_providers_snapshot_response",
+        payload: {
+          entries: [],
+          compactSnapshot: {
+            entries: [
+              {
+                provider: "pi",
+                status: "ready",
+                enabled: true,
+                models: [{ id: "model-a", label: "Model A", thinkingSet: 0 }],
+              },
+            ],
+            thinkingSets: [
+              {
+                options: [{ id: "high", label: "High", isDefault: true }],
+                defaultOptionId: "high",
+              },
+            ],
+          },
+          snapshotHash: "snapshot-hash",
+          generatedAt: "2026-08-04T00:00:00.000Z",
+          requestId: "provider-snapshot",
+        },
+      },
+    };
+
+    expect(GeneratedWSOutboundMessageSchema.safeParse(envelope)).toEqual({
+      success: true,
+      data: envelope,
+    });
+  });
+
   it.each([
     {
       name: "dedicated attention message",

packages/server/src/server/session.ts

@@ -841,6 +841,7 @@ export class Session {
         emit: (msg) => this.emit(msg),
         isProviderVisibleToClient: (provider) => this.isProviderVisibleToClient(provider),
         supportsCustomModeIcons: () => this.supports(CLIENT_CAPS.customModeIcons),
+        supportsCompactProviderSnapshots: () => this.supports(CLIENT_CAPS.compactProviderSnapshots),
         listProviderAvailability: () => this.agentManager.listProviderAvailability(),
         listDraftFeatures: (config) => this.agentManager.listDraftFeatures(config),
       },

packages/server/src/server/session/provider/provider-catalog-session.test.ts

@@ -13,12 +13,14 @@ import {
 } from "../../agent/provider-snapshot-manager.js";
 import type { ProviderSnapshotEntry } from "../../agent/agent-sdk-types.js";
 import type { ProviderUsageService } from "../../../services/quota-fetcher/service.js";
+import { expandProviderSnapshot } from "@getpaseo/protocol/provider-snapshot-codec";
 
 type SnapshotChangeHandler = (entries: ProviderSnapshotEntry[], cwd: string) => void;
 
 interface MakeOptions {
   visibleProviders?: Set<string>;
   supportsCustomModeIcons?: boolean;
+  supportsCompactProviderSnapshots?: boolean;
   snapshot?: { [K in keyof ProviderSnapshotManager]?: unknown };
   usage?: { [K in keyof ProviderUsageService]?: unknown };
   host?: Partial<ProviderCatalogSessionHost>;
@@ -49,6 +51,7 @@ function makeSubsystem(options: MakeOptions = {}) {
     emit: (msg) => emitted.push(msg),
     isProviderVisibleToClient: (provider) => visible.has(provider),
     supportsCustomModeIcons: () => options.supportsCustomModeIcons ?? false,
+    supportsCompactProviderSnapshots: () => options.supportsCompactProviderSnapshots ?? false,
     listProviderAvailability: async () => [],
     listDraftFeatures: async () => [],
     ...options.host,
@@ -113,6 +116,21 @@ describe("ProviderCatalogSession", () => {
     expect(pull?.payload.entries).toEqual(push?.payload.entries);
   });
 
+  it("pushes the compact encoding to capable clients", () => {
+    const { subsystem, emitted, pushSnapshotChange } = makeSubsystem({
+      supportsCustomModeIcons: true,
+      supportsCompactProviderSnapshots: true,
+    });
+
+    subsystem.start();
+    pushSnapshotChange(makeEntries());
+
+    const push = findByType(emitted, "providers_snapshot_update");
+    expect(push?.payload.entries).toEqual([]);
+    expect(push?.payload.snapshotHash).toEqual(expect.any(String));
+    expect(expandProviderSnapshot(push!.payload.compactSnapshot!)).toEqual([makeEntries()[0]]);
+  });
+
   it("preserves custom mode icons when the client supports them", async () => {
     const { subsystem, emitted } = makeSubsystem({
       supportsCustomModeIcons: true,
@@ -128,6 +146,60 @@ describe("ProviderCatalogSession", () => {
     expect(pull?.payload.entries[0]?.modes?.[0]?.icon).toBe("Sparkles");
   });
 
+  it("sends capable clients a compact snapshot and returns not-modified for its hash", async () => {
+    const thinkingOptions = [
+      { id: "low", label: "Low" },
+      { id: "high", label: "High", isDefault: true },
+    ];
+    const entries: ProviderSnapshotEntry[] = [
+      {
+        provider: "codex",
+        status: "ready",
+        enabled: true,
+        models: ["one", "two"].map((id) => ({
+          provider: "codex",
+          id,
+          label: id,
+          thinkingOptions,
+          defaultThinkingOptionId: "high",
+        })),
+      },
+    ];
+    const { subsystem, emitted } = makeSubsystem({
+      supportsCompactProviderSnapshots: true,
+      snapshot: { getSnapshot: () => entries },
+    });
+
+    await subsystem.handleGetProvidersSnapshotRequest({
+      type: "get_providers_snapshot_request",
+      requestId: "compact-1",
+    });
+
+    const first = findByType(emitted, "get_providers_snapshot_response");
+    expect(first?.payload.entries).toEqual([]);
+    expect(first?.payload.snapshotHash).toEqual(expect.any(String));
+    expect(first?.payload.compactSnapshot?.thinkingSets).toHaveLength(1);
+    expect(expandProviderSnapshot(first!.payload.compactSnapshot!)).toEqual(entries);
+
+    await subsystem.handleGetProvidersSnapshotRequest({
+      type: "get_providers_snapshot_request",
+      requestId: "compact-2",
+      ifNoneMatch: first?.payload.snapshotHash,
+    });
+
+    const responses = emitted.filter(
+      (message) => message.type === "get_providers_snapshot_response",
+    );
+    const second = responses[1];
+    expect(second?.payload).toMatchObject({
+      entries: [],
+      snapshotHash: first?.payload.snapshotHash,
+      notModified: true,
+      requestId: "compact-2",
+    });
+    expect(second?.payload.compactSnapshot).toBeUndefined();
+  });
+
   it("reports a disabled provider on list_provider_models without warming the snapshot", async () => {
     // warmUpSnapshotForCwd is intentionally unstubbed: createStub throws if it is called,
     // so the disabled short-circuit is proven by the absence of a throw.

packages/server/src/server/session/provider/provider-catalog-session.ts

@@ -1,5 +1,10 @@
 import type pino from "pino";
+import { createHash } from "node:crypto";
 import { getErrorMessage } from "@getpaseo/protocol/error-utils";
+import {
+  compactProviderSnapshot,
+  type CompactProviderSnapshot,
+} from "@getpaseo/protocol/provider-snapshot-codec";
 import type { SessionInboundMessage, SessionOutboundMessage } from "../../messages.js";
 import {
   isGlobalProviderSnapshotKey,
@@ -39,6 +44,7 @@ export interface ProviderCatalogSessionHost {
   isProviderVisibleToClient(provider: string): boolean;
   // COMPAT(customModeIcons): reads clientCapabilities live.
   supportsCustomModeIcons(): boolean;
+  supportsCompactProviderSnapshots(): boolean;
   listProviderAvailability(): Promise<ProviderAvailability[]>;
   listDraftFeatures(config: AgentSessionConfig): Promise<AgentFeature[]>;
 }
@@ -50,6 +56,19 @@ export interface ProviderCatalogSessionOptions {
   logger: pino.Logger;
 }
 
+interface EncodedProviderSnapshot {
+  compactSnapshot: CompactProviderSnapshot;
+  snapshotHash: string;
+}
+
+function encodeProviderSnapshot(entries: ProviderSnapshotEntry[]): EncodedProviderSnapshot {
+  const compactSnapshot = compactProviderSnapshot(entries);
+  const snapshotHash = createHash("sha256")
+    .update(JSON.stringify(compactSnapshot))
+    .digest("base64url");
+  return { compactSnapshot, snapshotHash };
+}
+
 /**
  * A client's provider catalog surface: model / mode / feature listing, the providers
  * snapshot push + pull, provider diagnostics, and usage. The snapshot PUSH (start) and
@@ -78,11 +97,25 @@ export class ProviderCatalogSession {
         this.host.isProviderVisibleToClient(entry.provider),
       );
       const snapshotCwd = isGlobalProviderSnapshotKey(cwd) ? undefined : cwd;
+      const clientEntries = this.downgradeEntryModesForClient(visibleEntries);
+      if (this.host.supportsCompactProviderSnapshots()) {
+        const encoded = encodeProviderSnapshot(clientEntries);
+        this.host.emit({
+          type: "providers_snapshot_update",
+          payload: {
+            ...(snapshotCwd ? { cwd: snapshotCwd } : {}),
+            entries: [],
+            ...encoded,
+            generatedAt: new Date().toISOString(),
+          },
+        });
+        return;
+      }
       this.host.emit({
         type: "providers_snapshot_update",
         payload: {
           ...(snapshotCwd ? { cwd: snapshotCwd } : {}),
-          entries: this.downgradeEntryModesForClient(visibleEntries),
+          entries: clientEntries,
           generatedAt: new Date().toISOString(),
         },
       });
@@ -360,11 +393,29 @@ export class ProviderCatalogSession {
     const entries = this.providerSnapshotManager
       .getSnapshot(msg.cwd ? expandTilde(msg.cwd) : undefined)
       .filter((entry) => this.host.isProviderVisibleToClient(entry.provider));
+    const clientEntries = this.downgradeEntryModesForClient(entries);
+
+    if (this.host.supportsCompactProviderSnapshots()) {
+      const encoded = encodeProviderSnapshot(clientEntries);
+      const notModified = msg.ifNoneMatch === encoded.snapshotHash;
+      this.host.emit({
+        type: "get_providers_snapshot_response",
+        payload: {
+          entries: [],
+          ...(!notModified ? { compactSnapshot: encoded.compactSnapshot } : {}),
+          snapshotHash: encoded.snapshotHash,
+          ...(notModified ? { notModified: true } : {}),
+          generatedAt: new Date().toISOString(),
+          requestId: msg.requestId,
+        },
+      });
+      return;
+    }
 
     this.host.emit({
       type: "get_providers_snapshot_response",
       payload: {
-        entries: this.downgradeEntryModesForClient(entries),
+        entries: clientEntries,
         generatedAt: new Date().toISOString(),
         requestId: msg.requestId,
       },