diff --git a/libs/api/tracker/application/src/index.ts b/libs/api/tracker/application/src/index.ts
index 85cfcfb..c598e51 100644
--- a/libs/api/tracker/application/src/index.ts
+++ b/libs/api/tracker/application/src/index.ts
@@ -8,6 +8,7 @@ export * from './lib/releases.service';
 export * from './lib/changes.service';
 export * from './lib/workflows.service';
 export * from './lib/blockers.service';
+export * from './lib/proposal-quota.service';
 export * from './lib/notifications.service';
 export * from './lib/notifications';
 export * from './lib/saved-filters.service';
diff --git a/libs/api/tracker/application/src/lib/proposal-quota.service.spec.ts b/libs/api/tracker/application/src/lib/proposal-quota.service.spec.ts
new file mode 100644
index 0000000..7600cb9
--- /dev/null
+++ b/libs/api/tracker/application/src/lib/proposal-quota.service.spec.ts
@@ -0,0 +1,22 @@
+import { ProposalQuota } from './proposal-quota.service';
+import { RateLimitStore } from './ports/rate-limit.store';
+
+class MemoryStore extends RateLimitStore {
+  readonly counts = new Map<string, number>();
+  async hit(key: string): Promise<number> {
+    const count = (this.counts.get(key) ?? 0) + 1;
+    this.counts.set(key, count);
+    return count;
+  }
+}
+
+describe('ProposalQuota', () => {
+  it('lets five proposals through per address, then says no', async () => {
+    const quota = new ProposalQuota(new MemoryStore());
+    const answers = [];
+    for (let i = 0; i < 6; i++) answers.push(await quota.take('1.2.3.4'));
+
+    expect(answers).toEqual([true, true, true, true, true, false]);
+    expect(await quota.take('5.6.7.8')).toBe(true);
+  });
+});
diff --git a/libs/api/tracker/application/src/lib/proposal-quota.service.ts b/libs/api/tracker/application/src/lib/proposal-quota.service.ts
new file mode 100644
index 0000000..fc2b7a9
--- /dev/null
+++ b/libs/api/tracker/application/src/lib/proposal-quota.service.ts
@@ -0,0 +1,21 @@
+import { Injectable } from '@nestjs/common';
+import { RateLimitStore } from './ports/rate-limit.store';
+
+/** Proposals from one address within the window. */
+const LIMIT = 5;
+const WINDOW_MS = 15 * 60_000;
+
+/**
+ * Keeps one address from flooding a project with proposals. Counted in
+ * Redis, so the limit holds across every instance of the API.
+ */
+@Injectable()
+export class ProposalQuota {
+  constructor(private readonly store: RateLimitStore) {}
+
+  /** Counts one more proposal from `address`; false once it is over. */
+  async take(address: string): Promise<boolean> {
+    const count = await this.store.hit(`proposals:${address}`, WINDOW_MS);
+    return count <= LIMIT;
+  }
+}
diff --git a/libs/api/tracker/application/src/lib/tracker-application.module.ts b/libs/api/tracker/application/src/lib/tracker-application.module.ts
index 2df214e..364cf3d 100644
--- a/libs/api/tracker/application/src/lib/tracker-application.module.ts
+++ b/libs/api/tracker/application/src/lib/tracker-application.module.ts
@@ -18,6 +18,7 @@ import { ReleasesService } from './releases.service';
 import { SAGAS } from './sagas/sagas';
 import { WorkflowsService } from './workflows.service';
 import { BlockersService } from './blockers.service';
+import { ProposalQuota } from './proposal-quota.service';
 import { NotificationsService } from './notifications.service';
 import { Notifier } from './notifications/notifier';
 import { NotificationsEventHandler } from './notifications/notifications.event-handler';
@@ -69,6 +70,7 @@ const SERVICES = [
   WebhooksService,
   TransferService,
   AutomationsService,
+  ProposalQuota,
 ];
 
 /**
diff --git a/libs/api/tracker/presenters/src/lib/http/proposal-limiter.ts b/libs/api/tracker/presenters/src/lib/http/proposal-limiter.ts
index 300e16b..0c07c6e 100644
--- a/libs/api/tracker/presenters/src/lib/http/proposal-limiter.ts
+++ b/libs/api/tracker/presenters/src/lib/http/proposal-limiter.ts
@@ -1,21 +1,13 @@
 import { HttpException, HttpStatus, Injectable } from '@nestjs/common';
-import { RateLimitStore } from '@task-stream/api/tracker/application';
+import { ProposalQuota } from '@task-stream/api/tracker/application';
 
-/** Proposals from one address within the window. */
-const LIMIT = 5;
-const WINDOW_MS = 15 * 60_000;
-
-/**
- * Keeps one address from flooding a project with proposals. Counted in
- * Redis, so the limit holds across every instance of the API.
- */
+/** The proposal quota, as the HTTP answer: 429 once it is used up. */
 @Injectable()
 export class ProposalLimiter {
-  constructor(private readonly store: RateLimitStore) {}
+  constructor(private readonly quota: ProposalQuota) {}
 
   async take(address: string): Promise<void> {
-    const count = await this.store.hit(`proposals:${address}`, WINDOW_MS);
-    if (count > LIMIT)
+    if (!(await this.quota.take(address)))
       throw new HttpException(
         'Too many proposals from here; try again in a few minutes',
         HttpStatus.TOO_MANY_REQUESTS,