diff --git a/services/hackbot-api/app/config.py b/services/hackbot-api/app/config.py
index bd245620a2..013517992a 100644
--- a/services/hackbot-api/app/config.py
+++ b/services/hackbot-api/app/config.py
@@ -104,6 +104,13 @@ class Settings(BaseSettings):
     push_auth_audience: str = ""
     push_auth_service_account: str = ""
 
+    # Run-completion email to the requester (see app/notifications.py). The
+    # override replaces the recipient so a dev deployment never mails real people.
+    hackbot_ui_url: str = "http://localhost:3000"
+    sendgrid_api_key: str = ""
+    notification_sender: str = ""
+    notification_override_email: str = ""
+
     # Server
     port: int = 8080
     environment: str = "development"
diff --git a/services/hackbot-api/app/notifications.py b/services/hackbot-api/app/notifications.py
new file mode 100644
index 0000000000..9d6c43d039
--- /dev/null
+++ b/services/hackbot-api/app/notifications.py
@@ -0,0 +1,86 @@
+"""Email the person who requested a run when it reaches a terminal state.
+
+A run launched from the UI carries its requester's email. Once the run has
+succeeded, failed or timed out, that address gets a short note with the
+outcome and a link to the run page, so nobody has to keep a tab open. Runs
+with no requester (triggered by webhooks) are skipped.
+
+This module only composes and delivers the message. It keeps no state, so
+calling it once per run is the caller's job. Delivery is best-effort: a
+failed send is logged, never raised. Only the requester is addressed; this
+is a personal ping, not a report.
+"""
+
+import asyncio
+import logging
+from pathlib import Path
+from string import Template
+
+import sendgrid
+from sendgrid.helpers.mail import From, HtmlContent, Mail, Subject, To
+
+from app.config import settings
+from app.database.models import Run
+
+log = logging.getLogger(__name__)
+
+# A stalled SendGrid call must not hold finalization open.
+_SEND_TIMEOUT_SECONDS = 10
+
+_TEMPLATES = Path(__file__).parent / "templates"
+_HTML_TEMPLATE = Template((_TEMPLATES / "run_completed.html").read_text())
+
+
+def run_url(run_id: str) -> str:
+    return f"{settings.hackbot_ui_url.rstrip('/')}/runs/{run_id}"
+
+
+def build_message(run: Run) -> tuple[str, str]:
+    """Compose the subject and HTML body of the notice for ``run``."""
+    outcome = run.status.replace("_", " ")
+    label = f"{run.agent} run {str(run.run_id)[:8]}"
+    bug_id = run.inputs.get("bug_id")
+    if bug_id is not None:
+        label += f" for bug {bug_id}"
+    subject = f"[Hackbot] {label} {outcome}"
+
+    values = {"label": label, "outcome": outcome, "url": run_url(str(run.run_id))}
+    html_body = _HTML_TEMPLATE.substitute(values)
+    return subject, html_body
+
+
+def _recipient(run: Run) -> str:
+    return settings.notification_override_email.strip() or run.requested_by
+
+
+def _send_sync(recipient: str, subject: str, html_body: str) -> int:
+    message = Mail(
+        From(settings.notification_sender),
+        To(recipient),
+        Subject(subject),
+        html_content=HtmlContent(html_body),
+    )
+    client = sendgrid.SendGridAPIClient(api_key=settings.sendgrid_api_key)
+    # The SendGrid wrapper has no timeout option; its HTTP client does.
+    client.client.timeout = _SEND_TIMEOUT_SECONDS
+    response = client.send(message=message)
+    return response.status_code
+
+
+async def notify_requester(run: Run) -> bool:
+    """Mail the run's requester about its terminal state. Returns whether it sent."""
+    recipient = _recipient(run)
+    subject, html_body = build_message(run)
+    try:
+        status_code = await asyncio.to_thread(_send_sync, recipient, subject, html_body)
+    except Exception:
+        log.exception("Failed to notify %s about run %s", recipient, run.run_id)
+        return False
+    log.info(
+        "Notified %s about run %s (%s): SendGrid %s",
+        recipient,
+        run.run_id,
+        run.status,
+        status_code,
+    )
+    return True
diff --git a/services/hackbot-api/app/routers/events.py b/services/hackbot-api/app/routers/events.py
index d46da7ab6d..a31935a494 100644
--- a/services/hackbot-api/app/routers/events.py
+++ b/services/hackbot-api/app/routers/events.py
@@ -7,6 +7,7 @@
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
+from app import notifications
 from app.actions_applier import on_run_completed
 from app.auth import require_push_auth
 from app.database.connection import get_db
@@ -24,9 +25,8 @@
 def _decode_pubsub_push_body(body: dict) -> dict:
     """Decode a standard Pub/Sub push envelope's `message.data` as JSON.
 
-    Both the completion-log push subscription feeding agent-run-finished and the
-    `agent-run-events` action-applier subscription deliver via this same
-    envelope shape.
+    The completion-log, action-applier and requester-notification subscriptions
+    deliver via this same envelope shape.
     """
     message = body.get("message") or {}
     data = message.get("data")
@@ -135,3 +135,23 @@ async def apply_run_actions(
         return
 
     await on_run_completed(db, run)
+
+
+@router.post("/notify-requester", status_code=204)
+async def notify_requester(
+    request: Request, db: AsyncSession = Depends(get_db)
+) -> None:
+    """Consumer of `run.completed`: email the run's requester.
+
+    Its own subscription includes all terminal outcomes.
+    """
+    event = _decode_pubsub_push_body(await request.json())
+    run_id = event["run_id"]
+
+    run = await db.get(Run, uuid.UUID(run_id))
+    if run is None:
+        log.warning("No run found for run_id %s", run_id)
+        return
+
+    if run.requested_by:
+        await notifications.notify_requester(run)
diff --git a/services/hackbot-api/app/templates/run_completed.html b/services/hackbot-api/app/templates/run_completed.html
new file mode 100644
index 0000000000..a6a765b237
--- /dev/null
+++ b/services/hackbot-api/app/templates/run_completed.html
@@ -0,0 +1,7 @@
+<!doctype html>
+<html>
+  <body>
+    <p>Your <strong>$label</strong> has <strong>$outcome</strong>.</p>
+    <p><a href="$url">Open the run</a></p>
+  </body>
+</html>
diff --git a/services/hackbot-api/tests/test_events.py b/services/hackbot-api/tests/test_events.py
index 214ca8e912..336e01a8a7 100644
--- a/services/hackbot-api/tests/test_events.py
+++ b/services/hackbot-api/tests/test_events.py
@@ -6,7 +6,13 @@
 
 import base64
 import json
+import uuid
+from types import SimpleNamespace
 
+import pytest
+from app import notifications
+from app.auth import require_push_auth
+from app.database.models import Run
 from app.routers.events import (
     _decode_pubsub_push_body,
     _execution_name_from_completion_log,
@@ -73,3 +79,62 @@ def test_execution_name_falls_back_to_labels():
 def test_execution_name_missing():
     assert _execution_name_from_completion_log({"protoPayload": {}}) is None
     assert _execution_name_from_completion_log({}) is None
+
+
+@pytest.mark.parametrize("status", ["succeeded", "failed", "timed_out"])
+def test_notify_requester_consumes_completed_event(client, db, monkeypatch, status):
+    run = SimpleNamespace(
+        run_id=uuid.uuid4(), status=status, requested_by="someone@mozilla.com"
+    )
+    notified = []
+
+    async def get(model, key):
+        assert model is Run
+        assert key == run.run_id
+        return run
+
+    async def notify(value):
+        notified.append(value)
+        return True
+
+    monkeypatch.setattr(db, "get", get)
+    monkeypatch.setattr(notifications, "notify_requester", notify)
+    client.app.dependency_overrides[require_push_auth] = lambda: None
+    response = client.post(
+        "/internal/events/notify-requester",
+        json=_push_envelope({"run_id": str(run.run_id), "status": status}),
+    )
+    assert response.status_code == 204
+    assert notified == [run]
+
+
+def test_notify_requester_skips_missing_run(client, monkeypatch):
+    async def notify(run):
+        pytest.fail("No email should be sent without a run")
+
+    monkeypatch.setattr(notifications, "notify_requester", notify)
+    client.app.dependency_overrides[require_push_auth] = lambda: None
+    response = client.post(
+        "/internal/events/notify-requester",
+        json=_push_envelope({"run_id": str(uuid.uuid4())}),
+    )
+    assert response.status_code == 204
+
+
+def test_notify_requester_skips_run_without_requester(client, db, monkeypatch):
+    run = SimpleNamespace(run_id=uuid.uuid4(), requested_by=None)
+
+    async def get(model, key):
+        return run
+
+    async def notify(value):
+        pytest.fail("No email should be sent without a requester")
+
+    monkeypatch.setattr(db, "get", get)
+    monkeypatch.setattr(notifications, "notify_requester", notify)
+    client.app.dependency_overrides[require_push_auth] = lambda: None
+    response = client.post(
+        "/internal/events/notify-requester",
+        json=_push_envelope({"run_id": str(run.run_id)}),
+    )
+    assert response.status_code == 204
diff --git a/services/hackbot-api/tests/test_finalize_run.py b/services/hackbot-api/tests/test_finalize_run.py
index 0ed627902e..7edfc6b006 100644
--- a/services/hackbot-api/tests/test_finalize_run.py
+++ b/services/hackbot-api/tests/test_finalize_run.py
@@ -10,7 +10,7 @@
 from datetime import datetime, timezone
 
 import pytest
-from app import gcs, jobs, pubsub
+from app import gcs, jobs, notifications, pubsub
 from app.jobs import ExecutionStatus
 from app.routers import runs as runs_module
 from app.routers.runs import finalize_run
@@ -48,6 +48,18 @@ async def fake_publish(run_id, agent, status):
     return published
 
 
+@pytest.fixture(autouse=True)
+def _no_notify(monkeypatch):
+    notified = []
+
+    async def fake_notify(run):
+        notified.append(run)
+        return True
+
+    monkeypatch.setattr(notifications, "notify_requester", fake_notify)
+    return notified
+
+
 async def test_noop_when_already_finalized(monkeypatch):
     run = _FakeRun(finalized_at=datetime.now(timezone.utc))
     db = _FakeDB()
diff --git a/services/hackbot-api/tests/test_notifications.py b/services/hackbot-api/tests/test_notifications.py
new file mode 100644
index 0000000000..935828829a
--- /dev/null
+++ b/services/hackbot-api/tests/test_notifications.py
@@ -0,0 +1,83 @@
+"""Tests for the run-completion email to the requester (app/notifications.py)."""
+
+import uuid
+from dataclasses import dataclass, field
+
+import pytest
+from app import notifications
+from app.config import settings
+from app.notifications import build_message, notify_requester
+from app.schemas import RunStatus
+
+
+@dataclass
+class _FakeRun:
+    run_id: uuid.UUID = field(default_factory=uuid.uuid4)
+    agent: str = "bug-fix"
+    status: str = RunStatus.succeeded.value
+    requested_by: str | None = "someone@mozilla.com"
+    inputs: dict = field(default_factory=dict)
+
+
+@pytest.fixture
+def sent(monkeypatch):
+    """Capture outgoing mail instead of hitting SendGrid."""
+    calls = []
+
+    def fake_send(recipient, subject, html_body):
+        calls.append((recipient, subject, html_body))
+        return 202
+
+    monkeypatch.setattr(notifications, "_send_sync", fake_send)
+    monkeypatch.setattr(settings, "sendgrid_api_key", "sg-test")
+    monkeypatch.setattr(settings, "notification_sender", "hackbot@mozilla.com")
+    monkeypatch.setattr(settings, "notification_override_email", "")
+    return calls
+
+
+def test_build_message_links_to_run_page(monkeypatch):
+    monkeypatch.setattr(settings, "hackbot_ui_url", "https://ui.example/")
+    run = _FakeRun(status=RunStatus.timed_out.value)
+    subject, html_body = build_message(run)
+    url = f"https://ui.example/runs/{run.run_id}"
+    assert subject == f"[Hackbot] bug-fix run {str(run.run_id)[:8]} timed out"
+    assert f"bug-fix run {str(run.run_id)[:8]}" in html_body
+    assert f'<a href="{url}">' in html_body
+    assert "<strong>timed out</strong>" in html_body
+
+
+async def test_sends_to_requester(sent):
+    run = _FakeRun()
+    assert await notify_requester(run) is True
+    assert len(sent) == 1
+    recipient, subject, _ = sent[0]
+    assert recipient == "someone@mozilla.com"
+    assert subject == f"[Hackbot] bug-fix run {str(run.run_id)[:8]} succeeded"
+
+
+def test_build_message_includes_bug_id():
+    run = _FakeRun(
+        run_id=uuid.UUID("ab603010-c278-4d55-bc29-f89463f78906"),
+        inputs={"bug_id": 123456},
+    )
+    subject, html_body = build_message(run)
+    assert subject == "[Hackbot] bug-fix run ab603010 for bug 123456 succeeded"
+    assert "bug-fix run ab603010 for bug 123456" in html_body
+
+
+async def test_override_email_replaces_recipient(sent, monkeypatch):
+    monkeypatch.setattr(settings, "notification_override_email", "dev@example.com")
+    assert await notify_requester(_FakeRun()) is True
+    assert sent[0][0] == "dev@example.com"
+
+
+async def test_send_failure_is_logged_not_raised(monkeypatch, caplog):
+    monkeypatch.setattr(settings, "sendgrid_api_key", "sg-test")
+    monkeypatch.setattr(settings, "notification_sender", "hackbot@mozilla.com")
+
+    def boom(*_a):
+        raise RuntimeError("sendgrid down")
+
+    monkeypatch.setattr(notifications, "_send_sync", boom)
+    assert await notify_requester(_FakeRun()) is False
+    assert "Failed to notify" in caplog.text