fix(desktop): invalidate artifact previews after deletion

apps/desktop/src/main/__tests__/main-startup-lifetime.test.ts

@@ -124,6 +124,21 @@ test('does not release renderer IPC before persistent handlers are registered',
   assert.doesNotMatch(readyBody, /runtimeHostManager\?\.start\(\)/u);
 });
 
+test('wires Artifact deletion and purge events to preview invalidation for the active scope', () => {
+  const subscribe = bootSource.indexOf('client.subscribeArtifactChanges(');
+  const unsubscribe = bootSource.indexOf('unsubscribeArtifactChanges();', subscribe);
+  assert.ok(subscribe >= 0 && unsubscribe > subscribe);
+  const handler = bootSource.slice(subscribe, unsubscribe);
+  assert.match(handler, /managedArtifactPreview\.revoke\(scope\.targetEpoch,\s*frame\.sessionId,\s*frame\.artifactId\)/u);
+  assert.match(handler, /managedArtifactPreview\.releaseSession\(scope\.targetEpoch,\s*frame\.sessionId\)/u);
+  assert.match(bootSource, /managedArtifactPreview\.openScope\(scope\.targetEpoch\)/u);
+  assert.match(bootSource, /await managedArtifactPreview\.closeScope\(scope\.targetEpoch\)/u);
+  assert.ok(
+    bootSource.indexOf('await managedArtifactPreview.closeScope(scope.targetEpoch)') <
+      bootSource.indexOf('unsubscribeArtifactChanges();'),
+  );
+});
+
 test('resolves persisted locale before first post-settings recovery prompt', () => {
   const rendererRecoveryStart = earlyWindowSource.indexOf('onRendererProcessGone: async');
   const rendererRecovery = earlyWindowSource.slice(

apps/desktop/src/main/__tests__/managed-artifact-preview.test.ts

@@ -85,6 +85,8 @@ test('isolates leases by origin and rejects credentials for another preview', as
     await assert.rejects(fetch(first.url));
     assert.equal(await (await fetch(second.url)).text(), 'second');
     await assert.rejects(service.prepare('host1', client(), 's1', 'a1'), /closed/);
+    service.openScope('host1');
+    assert.equal(await (await fetch((await service.prepare('host1', client(), 's1', 'a1')).url)).text(), html);
     await service.revoke('host2', 's1', 'a1');
     await assert.rejects(fetch(second.url));
   } finally { await service.close(); }
@@ -136,18 +138,117 @@ test('close and cancellation during a stream cannot publish a live endpoint', as
   }
 });
 
-test('bounds concurrent preparations before allocating buffers or ports', async () => {
+test('bounds previews per session instead of starving another session', async () => {
   const service = new ManagedArtifactPreview();
   let resume!: () => void;
   const gate = new Promise<void>((resolve) => { resume = resolve; });
   const source = client();
-  const slow = { ...source, getArtifact: async (s: string, a: string) => { await gate; return source.getArtifact(s, a); } };
+  const slow = { ...source, getArtifact: async () => { await gate; return source.getArtifact('s1', 'a1'); } };
   const pending = Array.from({ length: 16 }, () => service.prepare('h', slow, 's1', 'a1'));
   try {
     await assert.rejects(service.prepare('h', slow, 's1', 'a1'), /Too many/);
+    const other = service.prepare('h', client('other'), 's2', 'a1');
     resume();
-    assert.equal((await Promise.all(pending)).length, 16);
-  } finally { resume(); await Promise.allSettled(pending); await service.close(); }
+    assert.equal((await other).reachable, true);
+    await Promise.all(pending);
+  } finally {
+    resume();
+    await Promise.allSettled(pending);
+    await service.close();
+  }
+});
+
+test('rejects previews above the global limit without invalidating existing sessions', async () => {
+  const service = new ManagedArtifactPreview();
+  try {
+    const endpoints = [];
+    for (let index = 0; index < 64; index += 1) {
+      endpoints.push(await service.prepare('h', client(`preview-${index}`), `s${index}`, 'a1'));
+    }
+    await assert.rejects(service.prepare('h', client('replacement'), 's64', 'a1'), /across the Desktop/);
+    assert.equal(await (await fetch(endpoints[0]!.url)).text(), 'preview-0');
+    assert.equal(await (await fetch(endpoints[63]!.url)).text(), 'preview-63');
+    await service.releaseUrl(endpoints[0]!.url);
+    const replacement = await service.prepare('h', client('replacement'), 's64', 'a1');
+    assert.equal(await (await fetch(replacement.url)).text(), 'replacement');
+  } finally {
+    await service.close();
+  }
+});
+
+test('reserves aggregate preview bytes before streaming and releases reservations on failure', async () => {
+  const service = new ManagedArtifactPreview();
+  let resume!: () => void;
+  const gate = new Promise<void>((resolve) => { resume = resolve; });
+  const large = {
+    getArtifact: async () => ({ id: 'a1', sessionId: 's1', turnId: 't1', createdAt: 0, name: 'large.html', kind: 'html' as const, sizeBytes: PREVIEW_MAX_BYTES, source: 'tool_result' as const }),
+    streamArtifact: async () => { await gate; throw new Error('test stream failure'); },
+  };
+  const successfulLarge = {
+    getArtifact: large.getArtifact,
+    streamArtifact: async (_sessionId: string, _artifactId: string, write: (chunk: Uint8Array) => Promise<void>) => {
+      const bytes = Buffer.alloc(PREVIEW_MAX_BYTES);
+      await write(bytes);
+      return bytes.length;
+    },
+  };
+  const pending = Array.from({ length: 16 }, (_, index) => service.prepare('h', large, `s${index + 1}`, 'a1'));
+  try {
+    // Each in-flight Artifact reserves 8 MiB, reaching the 128 MiB aggregate budget.
+    await new Promise((resolve) => setImmediate(resolve));
+    await assert.rejects(service.prepare('h', large, 's17', 'a1'), /memory limit/);
+    resume();
+    await Promise.all(pending.map((preparation) => assert.rejects(preparation, /test stream failure/)));
+    const recovered = await service.prepare('h', successfulLarge, 's1', 'a1');
+    assert.equal(recovered.reachable, true);
+    await service.releaseUrl(recovered.url);
+  } finally {
+    resume();
+    await Promise.allSettled(pending);
+    await service.close();
+  }
+});
+
+test('releases every preview for a purged session', async () => {
+  const service = new ManagedArtifactPreview();
+  try {
+    const first = await service.prepare('h', client(), 's1', 'a1');
+    const second = await service.prepare('h', client('second'), 's1', 'a2');
+    const otherScope = await service.prepare('other-host', client('other scope'), 's1', 'a1');
+    await service.releaseSession('h', 's1');
+    await assert.rejects(fetch(first.url));
+    await assert.rejects(fetch(second.url));
+    assert.equal(await (await fetch(otherScope.url)).text(), 'other scope');
+    assert.equal((await service.prepare('h', client(), 's1', 'a1')).reachable, true);
+  } finally { await service.close(); }
+});
+
+test('delete and Session purge cancel previews that are still preparing', async () => {
+  for (const release of [
+    (service: ManagedArtifactPreview) => service.revoke('h', 's1', 'a1'),
+    (service: ManagedArtifactPreview) => service.releaseSession('h', 's1'),
+  ]) {
+    const service = new ManagedArtifactPreview();
+    let resume!: () => void;
+    const gate = new Promise<void>((resolve) => { resume = resolve; });
+    const source = client();
+    const preparing = service.prepare('h', {
+      ...source,
+      getArtifact: async (...args) => {
+        await gate;
+        return source.getArtifact(...args);
+      },
+    }, 's1', 'a1');
+    try {
+      await release(service);
+      resume();
+      await assert.rejects(preparing, /closed/);
+    } finally {
+      resume();
+      await Promise.allSettled([preparing]);
+      await service.close();
+    }
+  }
 });
 
 test('tool binds to the admitted session and returns endpoint evidence only', async () => {

apps/desktop/src/main/__tests__/runtime-host-desktop-candidate.test.ts

@@ -62,6 +62,7 @@ import { RuntimeHostReconnectingIpcMain } from '../runtime-host-reconnecting-ipc
 import { desktopSessionResourceKey } from '../../shared/runtime-host-identity.js';
 import { waitFor as pollFor } from '@maka/core/test-only/async-primitives';
 import { canRepairManagedRuntimeHostStartup } from '../runtime-host-startup-recovery.js';
+import { ManagedArtifactPreview } from '../managed-artifact-preview.js';
 
 const TEST_HOST_ID = 'a'.repeat(64);
 const TEST_TARGET_EPOCH = 'test-target-epoch';
@@ -522,6 +523,67 @@ test('tears down the whole candidate when the Host connection closes', async ()
   assert.equal(host.closeCalls, 1);
 });
 
+test('closes old managed Artifact previews and reopens the scope after reconnect', async () => {
+  const ipc = ipcHarness();
+  const firstHost = connectionHarness('preview-first');
+  const preview = new ManagedArtifactPreview();
+  const bytes = Buffer.from('<!doctype html><title>Preview</title>');
+  const candidateDeps = {
+    ...deps(ipc),
+    registerClientIpc: (_client, _ipc, _controls, _target, scope) => {
+      preview.openScope(scope.targetEpoch);
+      return () => preview.closeScope(scope.targetEpoch);
+    },
+  } satisfies DesktopRuntimeHostCandidateDeps;
+  const firstCandidate = await createDesktopRuntimeHostCandidate(firstHost.connection, candidateDeps);
+  let secondCandidate: Awaited<ReturnType<typeof createDesktopRuntimeHostCandidate>> | undefined;
+  const source = {
+    getArtifact: async () => ({
+      id: 'artifact-1',
+      sessionId: 'session-1',
+      turnId: 'turn-1',
+      createdAt: 0,
+      name: 'preview.html',
+      kind: 'html' as const,
+      sizeBytes: bytes.length,
+      source: 'tool_result' as const,
+    }),
+    streamArtifact: async (_sessionId: string, _artifactId: string, write: (chunk: Uint8Array) => Promise<void>) => {
+      await write(bytes);
+      return bytes.length;
+    },
+  };
+
+  try {
+    const endpoint = await preview.prepare(
+      TEST_TARGET_EPOCH,
+      source,
+      'session-1',
+      'artifact-1',
+    );
+    assert.equal(await (await fetch(endpoint.url)).text(), bytes.toString());
+
+    firstHost.disconnect();
+    await firstCandidate.closed;
+
+    await assert.rejects(fetch(endpoint.url));
+
+    const secondHost = connectionHarness('preview-second');
+    secondCandidate = await createDesktopRuntimeHostCandidate(secondHost.connection, candidateDeps);
+    const replacement = await preview.prepare(
+      TEST_TARGET_EPOCH,
+      source,
+      'session-1',
+      'artifact-1',
+    );
+    assert.equal(await (await fetch(replacement.url)).text(), bytes.toString());
+  } finally {
+    await firstCandidate.close();
+    await secondCandidate?.close();
+    await preview.close();
+  }
+});
+
 test('preserves supported IPC when the connection closes before candidate startup returns', { timeout: 5_000 }, async (t) => {
   const ipc = ipcHarness();
   const router = new RuntimeHostReconnectingIpcMain(ipc);

apps/desktop/src/main/managed-artifact-preview.ts

@@ -24,6 +24,8 @@ import type { DesktopRuntimeHostClient } from './runtime-host-client.js';
 
 export const PREVIEW_MAX_BYTES = 8 * 1024 * 1024;
 const MAX_PREVIEWS = 16;
+const MAX_GLOBAL_PREVIEWS = 64;
+const MAX_GLOBAL_PREVIEW_BYTES = 128 * 1024 * 1024;
 const PREVIEW_TTL_MS = 30 * 60 * 1000;
 const READ_DEADLINE_MS = 30_000;
 
@@ -42,16 +44,22 @@ interface Lease {
   server: Server;
   timer?: ReturnType<typeof setTimeout>;
   url?: string;
+  reservedBytes: number;
 }
 
 /** Desktop-owned, bounded, ephemeral HTML snapshots. No workspace directory is served. */
 export class ManagedArtifactPreview {
   private readonly leases = new Set<Lease>();
   private readonly retiredScopes = new Set<string>();
+  private reservedBytes = 0;
   private closed = false;
 
   constructor(private readonly ttlMs = PREVIEW_TTL_MS) {}
 
+  openScope(scope: string): void {
+    this.retiredScopes.delete(scope);
+  }
+
   async releaseUrl(url: string): Promise<void> {
     const lease = [...this.leases].find((entry) => entry.url === url);
     if (lease) await this.release(lease);
@@ -68,10 +76,18 @@ export class ManagedArtifactPreview {
       throw new Error('Invalid Artifact identity');
     }
     if (this.closed || this.retiredScopes.has(scope)) throw new Error('Preview owner is closed');
-    if (this.leases.size >= MAX_PREVIEWS) throw new Error('Too many active previews; wait for expiry');
+    const sessionLeases = [...this.leases].filter(
+      (lease) => lease.scope === scope && lease.sessionId === sessionId,
+    );
+    if (sessionLeases.length >= MAX_PREVIEWS) {
+      throw new Error('Too many active previews; wait for expiry');
+    }
+    if (this.leases.size >= MAX_GLOBAL_PREVIEWS) {
+      throw new Error('Too many active previews across the Desktop; wait for expiry');
+    }
     signal?.throwIfAborted();
     // Reserve before asynchronous reads, so concurrent preparations cannot exceed the bound.
-    const lease: Lease = { scope, sessionId, artifactId, server: createServer() };
+    const lease: Lease = { scope, sessionId, artifactId, server: createServer(), reservedBytes: 0 };
     this.leases.add(lease);
     const assertActive = () => {
       signal?.throwIfAborted();
@@ -84,6 +100,11 @@ export class ManagedArtifactPreview {
       if (!Number.isSafeInteger(artifact.sizeBytes) || artifact.sizeBytes < 0 || artifact.sizeBytes > PREVIEW_MAX_BYTES) {
         throw new Error('HTML preview exceeds the 8 MiB limit; use Save As instead');
       }
+      if (this.reservedBytes + artifact.sizeBytes > MAX_GLOBAL_PREVIEW_BYTES) {
+        throw new Error('The Desktop preview memory limit has been reached; wait for previews to expire');
+      }
+      lease.reservedBytes = artifact.sizeBytes;
+      this.reservedBytes += lease.reservedBytes;
       const chunks: Buffer[] = [];
       let size = 0;
       const total = await withDeadline(client.streamArtifact(sessionId, artifactId, async (chunk) => {
@@ -156,6 +177,14 @@ export class ManagedArtifactPreview {
     await Promise.all([...this.leases].filter((lease) => lease.scope === scope && lease.sessionId === sessionId && lease.artifactId === artifactId).map((lease) => this.release(lease)));
   }
 
+  async releaseSession(scope: string, sessionId: string): Promise<void> {
+    await Promise.all(
+      [...this.leases]
+        .filter((lease) => lease.scope === scope && lease.sessionId === sessionId)
+        .map((lease) => this.release(lease)),
+    );
+  }
+
   async closeScope(scope: string): Promise<void> {
     this.retiredScopes.add(scope);
     await Promise.all([...this.leases].filter((lease) => lease.scope === scope).map((lease) => this.release(lease)));
@@ -167,7 +196,10 @@ export class ManagedArtifactPreview {
   }
 
   private async release(lease: Lease): Promise<void> {
-    this.leases.delete(lease);
+    if (this.leases.delete(lease)) {
+      this.reservedBytes -= lease.reservedBytes;
+      lease.reservedBytes = 0;
+    }
     clearTimeout(lease.timer);
     await new Promise<void>((resolve) => {
       lease.server.close(() => resolve());

apps/desktop/src/main/runtime-host-artifacts-ipc-main.ts

@@ -83,6 +83,8 @@ export function registerRuntimeHostArtifactsIpc(
     "artifacts:delete",
     async (_event, sessionId: string, artifactId: string) => {
       const result = await deps.client.deleteArtifact(sessionId, artifactId);
+      // Keep the direct revoke: the Host also publishes artifact.changed, but
+      // stopping the bytes here must not depend on feed delivery to this Client.
       await deps.preview?.service.revoke(deps.preview.scope, sessionId, artifactId);
       return result;
     },

apps/desktop/src/main/runtime-host-boot.ts

@@ -1562,6 +1562,13 @@ function registerHostClientIpc(
   const unsubscribeSessionCatalogChanges = client.subscribeSessionCatalogChanges(
     ({ sessionId }) => emitTargetSessionsChanged("updated", sessionId),
   );
+  const unsubscribeArtifactChanges = client.subscribeArtifactChanges((frame) => {
+    if (frame.reason === 'deleted') {
+      void managedArtifactPreview.revoke(scope.targetEpoch, frame.sessionId, frame.artifactId);
+    } else {
+      void managedArtifactPreview.releaseSession(scope.targetEpoch, frame.sessionId);
+    }
+  });
   const unsubscribeProjectCatalogChanges = client.subscribeProjectCatalogChanges(() => {
     sendToRenderer("projects:changed");
   });
@@ -1835,12 +1842,14 @@ function registerHostClientIpc(
   });
   registerOnboardingIpc({ onboardingService, ipcMain: scopedIpc });
   registerTaskSubmissionReadinessIpc(taskSubmissionReadinessService, scopedIpc);
+  managedArtifactPreview.openScope(scope.targetEpoch);
   return async () => {
     clientPluginTransport.release(client);
     unsubscribeConfigurationChanges();
     await managedArtifactPreview.closeScope(scope.targetEpoch);
     unsubscribeConnectionCatalogChanges();
     unsubscribeSessionCatalogChanges();
+    unsubscribeArtifactChanges();
     unsubscribeProjectCatalogChanges();
     unsubscribeScheduledTaskChanges();
     runtimePolicyTargets.delete(target);

apps/desktop/src/main/runtime-host-client.ts

@@ -102,6 +102,7 @@ import {
   type ProjectDirectoryEntry,
   type ProjectDirectoryRoot,
   SESSION_TRANSCRIPT_BOOTSTRAP_MAX_BYTES,
+  type ArtifactChangedFrame,
   type SessionCatalogChangedFrame,
   type ScheduledTaskChangedFrame,
   type SessionCatalogItem,
@@ -393,6 +394,11 @@ export class DesktopRuntimeHostClient {
     return this.connection.subscribeConfigurationChanges(listener);
   }
 
+  subscribeArtifactChanges(listener: (frame: ArtifactChangedFrame) => void): () => void {
+    this.#assertOpen();
+    return this.connection.subscribeArtifactChanges(listener);
+  }
+
   subscribeConnectionCatalogChanges(listener: (revision: number) => void): () => void {
     this.#assertOpen();
     return this.connection.subscribeConnectionCatalogChanges(listener);

packages/cli/src/__tests__/acp-stdio-server.test.ts

@@ -708,6 +708,7 @@ describe('Maka ACP stdio server', () => {
         return subscription;
       },
       subscribeConfigurationChanges: () => () => undefined,
+      subscribeArtifactChanges: () => () => undefined,
       subscribeConnectionCatalogChanges: () => () => undefined,
       subscribeProjectCatalogChanges: () => () => undefined,
       subscribeSessionCatalogChanges: () => () => undefined,