diff --git a/packages/cli/src/commands/mail-watch.ts b/packages/cli/src/commands/mail-watch.ts
index 3e10ae0..ca6e621 100644
--- a/packages/cli/src/commands/mail-watch.ts
+++ b/packages/cli/src/commands/mail-watch.ts
@@ -269,7 +269,11 @@ export function xmlEscape(s: string): string {
     .replace(/'/g, "'");
 }
 
-function buildPlist(agent: string, tpsBin: string, extraHookArgs: string[]): string {
+/**
+ * Build the launchd plist for an agent's mail-watch daemon.
+ * Exported for unit testing (asserts ProcessType=Background + valid XML).
+ */
+export function buildPlist(agent: string, tpsBin: string, extraHookArgs: string[]): string {
   const label = plistLabel(agent);
   const stdout = join(logDir(), `mail-watch-${agent}.log`);
   const stderr = join(logDir(), `mail-watch-${agent}.error.log`);
@@ -309,8 +313,18 @@ ${progArgs}
     <true/>
   </dict>
 
+  <!--
+    ProcessType=Background tells launchd this is a long-lived background daemon.
+    Without it, the watcher's idle poll timer (waking every ~15s) gets the job
+    power-classified as "inefficient" and macOS reaps it with a clean exit 0 —
+    which KeepAlive(Crashed:true) does NOT restart, so the agent goes silently
+    deaf. Background processing type opts the job out of that idle-reap. (ops-bayh)
+  -->
+  <key>ProcessType</key>
+  <string>Background</string>
+
   <key>ThrottleInterval</key>
-  <integer>5</integer>
+  <integer>10</integer>
 
   <key>StandardOutPath</key>
   <string>${xmlEscape(stdout)}</string>
diff --git a/packages/cli/test/mail-watch.test.ts b/packages/cli/test/mail-watch.test.ts
index ffd7038..8bbdaa5 100644
--- a/packages/cli/test/mail-watch.test.ts
+++ b/packages/cli/test/mail-watch.test.ts
@@ -13,7 +13,9 @@ import { describe, it, expect, beforeEach, afterEach } from "bun:test";
 import { mkdirSync, rmSync, writeFileSync, renameSync } from "node:fs";
 import { join } from "node:path";
 import { tmpdir } from "node:os";
-import { validateAgentId, watchMail, xmlEscape } from "../src/commands/mail-watch.js";
+import { buildPlist, validateAgentId, watchMail, xmlEscape } from "../src/commands/mail-watch.js";
+import { execFileSync } from "node:child_process";
+import { platform } from "node:os";
 
 // ---------------------------------------------------------------------------
 // Helpers
@@ -288,6 +290,43 @@ describe("xmlEscape", () => {
   });
 });
 
+// ---------------------------------------------------------------------------
+// buildPlist — generated launchd plist shape (ops-bayh: idle-reap immunity)
+// ---------------------------------------------------------------------------
+
+describe("buildPlist", () => {
+  it("sets ProcessType=Background so macOS does not idle-reap the watcher", () => {
+    const xml = buildPlist("test-agent", "/usr/local/bin/tps.js", []);
+    expect(xml).toContain("<key>ProcessType</key>");
+    // The <string> follows the <key> on the next line — assert the pairing.
+    expect(xml).toMatch(/<key>ProcessType<\/key>\s*<string>Background<\/string>/);
+  });
+
+  it("sets a non-zero ThrottleInterval", () => {
+    const xml = buildPlist("test-agent", "/usr/local/bin/tps.js", []);
+    expect(xml).toMatch(/<key>ThrottleInterval<\/key>\s*<integer>10<\/integer>/);
+  });
+
+  it("keeps KeepAlive(Crashed:true) so a real crash still restarts", () => {
+    const xml = buildPlist("test-agent", "/usr/local/bin/tps.js", []);
+    expect(xml).toMatch(/<key>KeepAlive<\/key>\s*<dict>\s*<key>Crashed<\/key>\s*<true\/>/);
+  });
+
+  it("generates plist that passes plutil -lint (valid XML, macOS only)", () => {
+    if (platform() !== "darwin") return; // plutil is macOS-only
+    const xml = buildPlist("test-agent", "/usr/local/bin/tps.js", ["arg with spaces & <special>"]);
+    const tmpFile = join(tmpdir(), `buildplist-lint-${Date.now()}.plist`);
+    writeFileSync(tmpFile, xml);
+    try {
+      // Throws (non-zero exit) if the plist is malformed.
+      const out = execFileSync("plutil", ["-lint", tmpFile], { encoding: "utf-8" });
+      expect(out).toContain("OK");
+    } finally {
+      rmSync(tmpFile, { force: true });
+    }
+  });
+});
+
 // ---------------------------------------------------------------------------
 // Daemon install (macOS only — validates args without actually calling launchctl)
 // ---------------------------------------------------------------------------