diff --git a/packages/plugins/sandbox-providers/daytona/src/manifest.ts b/packages/plugins/sandbox-providers/daytona/src/manifest.ts
index c78ef2c00f..d1ebbc7096 100644
--- a/packages/plugins/sandbox-providers/daytona/src/manifest.ts
+++ b/packages/plugins/sandbox-providers/daytona/src/manifest.ts
@@ -84,16 +84,21 @@ const manifest: PaperclipPluginManifestV1 = {
           },
           autoStopInterval: {
             type: "number",
-            description: "Optional Daytona auto-stop interval in minutes. `0` disables auto-stop.",
+            description:
+              "Daytona auto-stop interval in minutes. `0` disables auto-stop. Defaults to 15 when unset.",
+            default: 15,
           },
           autoArchiveInterval: {
             type: "number",
-            description: "Optional Daytona auto-archive interval in minutes. `0` uses Daytona's max interval.",
+            description:
+              "Daytona auto-archive interval in minutes. Stopped sandboxes still count against the storage quota until archived, so this defaults to 60 when unset. `0` uses Daytona's max interval.",
+            default: 60,
           },
           autoDeleteInterval: {
             type: "number",
             description:
-              "Optional Daytona auto-delete interval in minutes. `-1` disables auto-delete and `0` deletes immediately after stop.",
+              "Daytona auto-delete interval in minutes. Backstop reaper for sandboxes nobody resumes; defaults to 10080 (7 days) when unset. `-1` disables auto-delete and `0` deletes immediately after stop.",
+            default: 10080,
           },
           reuseLease: {
             type: "boolean",
diff --git a/packages/plugins/sandbox-providers/daytona/src/plugin.test.ts b/packages/plugins/sandbox-providers/daytona/src/plugin.test.ts
index f594a07e27..fd8a3d24d9 100644
--- a/packages/plugins/sandbox-providers/daytona/src/plugin.test.ts
+++ b/packages/plugins/sandbox-providers/daytona/src/plugin.test.ts
@@ -115,6 +115,78 @@ describe("Daytona sandbox provider plugin", () => {
     });
   });
 
+  it("applies quota-safety auto-stop/archive/delete defaults when unset", async () => {
+    process.env.DAYTONA_API_KEY = "host-key";
+
+    const result = await plugin.definition.onEnvironmentValidateConfig?.({
+      driverKey: "daytona",
+      config: {
+        snapshot: "base-snapshot",
+        timeoutMs: 300000,
+        reuseLease: true,
+      },
+    });
+
+    expect(result).toMatchObject({
+      ok: true,
+      normalizedConfig: {
+        autoStopInterval: 15,
+        autoArchiveInterval: 60,
+        autoDeleteInterval: 10080,
+      },
+    });
+  });
+
+  it("preserves an explicit 0/-1 to disable auto intervals", async () => {
+    process.env.DAYTONA_API_KEY = "host-key";
+
+    const result = await plugin.definition.onEnvironmentValidateConfig?.({
+      driverKey: "daytona",
+      config: {
+        snapshot: "base-snapshot",
+        timeoutMs: 300000,
+        autoStopInterval: 0,
+        autoArchiveInterval: 0,
+        autoDeleteInterval: -1,
+        reuseLease: true,
+      },
+    });
+
+    expect(result).toMatchObject({
+      ok: true,
+      normalizedConfig: {
+        autoStopInterval: 0,
+        autoArchiveInterval: 0,
+        autoDeleteInterval: -1,
+      },
+    });
+  });
+
+  it("forwards auto-archive/auto-delete defaults to the Daytona create call", async () => {
+    process.env.DAYTONA_API_KEY = "host-key";
+    const sandbox = createMockSandbox();
+    mockCreate.mockResolvedValue(sandbox);
+
+    await plugin.definition.onEnvironmentAcquireLease?.({
+      driverKey: "daytona",
+      companyId: "company-1",
+      environmentId: "env-1",
+      runId: "run-1",
+      config: {
+        image: "node:20",
+        timeoutMs: 300000,
+        reuseLease: false,
+      },
+    });
+
+    const [createParams] = mockCreate.mock.calls[0] as [Record<string, unknown>];
+    expect(createParams).toMatchObject({
+      autoStopInterval: 15,
+      autoArchiveInterval: 60,
+      autoDeleteInterval: 10080,
+    });
+  });
+
   it("rejects ambiguous or invalid config", async () => {
     await expect(plugin.definition.onEnvironmentValidateConfig?.({
       driverKey: "daytona",
diff --git a/packages/plugins/sandbox-providers/daytona/src/plugin.ts b/packages/plugins/sandbox-providers/daytona/src/plugin.ts
index fb367debe2..b004c05195 100644
--- a/packages/plugins/sandbox-providers/daytona/src/plugin.ts
+++ b/packages/plugins/sandbox-providers/daytona/src/plugin.ts
@@ -52,6 +52,21 @@ type WorkspaceSentinelResult = {
 
 const WORKSPACE_SENTINEL_RELATIVE_PATH = ".paperclip-runtime/reusable-sandbox-lease.json";
 
+// Quota-safety defaults (minutes). Daytona counts *stopped* sandboxes against
+// the storage quota; only *archived* sandboxes move to cold object storage and
+// stop counting. Without these, stopped/leaked sandboxes accumulate until the
+// org quota fills. We apply sane defaults so every sandbox eventually leaves the
+// quota on its own even when our own cleanup fails or never runs (crashed runs,
+// failed lease destroys, orphaned probes). All three stay overridable per
+// environment; an explicit 0/-1 in config is preserved.
+//
+// - autoStop: stop idle *running* sandboxes (frees CPU/RAM, starts the archive clock).
+// - autoArchive: archive *stopped* sandboxes so they leave the disk quota.
+// - autoDelete: backstop reaper for sandboxes nobody resumes.
+const DEFAULT_AUTO_STOP_INTERVAL_MINUTES = 15;
+const DEFAULT_AUTO_ARCHIVE_INTERVAL_MINUTES = 60;
+const DEFAULT_AUTO_DELETE_INTERVAL_MINUTES = 7 * 24 * 60; // 7 days
+
 function parseOptionalString(value: unknown): string | null {
   return typeof value === "string" && value.trim().length > 0 ? value.trim() : null;
 }
@@ -82,9 +97,9 @@ function parseDriverConfig(raw: Record<string, unknown>): DaytonaDriverConfig {
     memory: parseOptionalNumber(raw.memory),
     disk: parseOptionalNumber(raw.disk),
     gpu: parseOptionalNumber(raw.gpu),
-    autoStopInterval: parseOptionalInteger(raw.autoStopInterval),
-    autoArchiveInterval: parseOptionalInteger(raw.autoArchiveInterval),
-    autoDeleteInterval: parseOptionalInteger(raw.autoDeleteInterval),
+    autoStopInterval: parseOptionalInteger(raw.autoStopInterval) ?? DEFAULT_AUTO_STOP_INTERVAL_MINUTES,
+    autoArchiveInterval: parseOptionalInteger(raw.autoArchiveInterval) ?? DEFAULT_AUTO_ARCHIVE_INTERVAL_MINUTES,
+    autoDeleteInterval: parseOptionalInteger(raw.autoDeleteInterval) ?? DEFAULT_AUTO_DELETE_INTERVAL_MINUTES,
     reuseLease: raw.reuseLease === true,
   };
 }