diff --git a/README.md b/README.md
index 1d24904..96feb82 100644
--- a/README.md
+++ b/README.md
@@ -27,5 +27,7 @@ complete entry-routing rule (landing / create-storefront / admin), and the INV-1
 whole-flow bootstrap test — all skinned to the Claude Design export
 (`wiggleverse-ecomm-content/ui/designs/ecomm-login-and-create-storefront-designs/`),
 which also re-skinned the SLICE-2 Landing + Sign-in screens. See
-[`docs/BOOTSTRAP.md`](./docs/BOOTSTRAP.md) to run it locally. Deployed environments
-(SLICE-4) are next.
+[`docs/BOOTSTRAP.md`](./docs/BOOTSTRAP.md) to run it locally. SLICE-4's deploy
+contract is in place (versioned `/healthz`, backend-served SPA, `SmtpMailer` with
+honest 502 on delivery failure); PPE provisioning + the bootstrap rehearsal are the
+remaining SLICE-4 steps (BOOTSTRAP.md's PPE section is the runbook).
diff --git a/VERSION b/VERSION
new file mode 100644
index 0000000..1d0ba9e
--- /dev/null
+++ b/VERSION
@@ -0,0 +1 @@
+0.4.0
diff --git a/backend/app/domains/accounts/__init__.py b/backend/app/domains/accounts/__init__.py
index 986d2a4..5987594 100644
--- a/backend/app/domains/accounts/__init__.py
+++ b/backend/app/domains/accounts/__init__.py
@@ -11,6 +11,7 @@ from .errors import (
     CodeExhausted,
     CodeExpired,
     CodeMismatch,
+    DeliveryFailed,
     InvalidEmail,
     ResendCooldown,
 )
@@ -25,6 +26,7 @@ __all__ = [
     "CodeMismatch",
     "CodeExpired",
     "CodeExhausted",
+    "DeliveryFailed",
     "request_code",
     "verify",
     "get_account",
diff --git a/backend/app/domains/accounts/errors.py b/backend/app/domains/accounts/errors.py
index 68ca901..5d68742 100644
--- a/backend/app/domains/accounts/errors.py
+++ b/backend/app/domains/accounts/errors.py
@@ -36,3 +36,7 @@ class CodeExpired(AccountsError):
 
 class CodeExhausted(AccountsError):
     """The code's attempt budget is spent; it is invalidated (INV-3 → §6.4 400 code_exhausted)."""
+
+
+class DeliveryFailed(AccountsError):
+    """The relay refused the code email; nothing was committed (INV-9 → §6.4 502 delivery_failed)."""
diff --git a/backend/app/domains/accounts/service.py b/backend/app/domains/accounts/service.py
index b6e5874..e9bc953 100644
--- a/backend/app/domains/accounts/service.py
+++ b/backend/app/domains/accounts/service.py
@@ -18,9 +18,16 @@ from datetime import datetime, timedelta, timezone
 import psycopg
 
 from app.platform import config
-from app.platform.mailer import Mailer
+from app.platform.mailer import Mailer, MailerError
 
-from .errors import CodeExhausted, CodeExpired, CodeMismatch, InvalidEmail, ResendCooldown
+from .errors import (
+    CodeExhausted,
+    CodeExpired,
+    CodeMismatch,
+    DeliveryFailed,
+    InvalidEmail,
+    ResendCooldown,
+)
 from .models import Account
 
 # INV-3 constants — the one-time-code policy.
@@ -82,17 +89,23 @@ def request_code(conn: psycopg.Connection, mailer: Mailer, email: str) -> None:
         "INSERT INTO auth_code (email, code_hash, expires_at) VALUES (%s, %s, %s)",
         (email, _hash_code(code), now + CODE_TTL),
     )
-    conn.commit()
 
-    mailer.send(
-        to=email,
-        subject=f"Your ecomm code: {code}",
-        body=(
-            f"Your ecomm one-time code is {code}.\n"
-            f"It is valid for {int(CODE_TTL.total_seconds() // 60)} minutes.\n"
-            "If you didn't request this, ignore this message."
-        ),
-    )
+    # Send BEFORE commit (ecomm#7): a refused delivery rolls the row back, so no orphan
+    # code blocks the 60s cooldown and the caller can honestly retry at once (INV-9).
+    try:
+        mailer.send(
+            to=email,
+            subject=f"Your ecomm code: {code}",
+            body=(
+                f"Your ecomm one-time code is {code}.\n"
+                f"It is valid for {int(CODE_TTL.total_seconds() // 60)} minutes.\n"
+                "If you didn't request this, ignore this message."
+            ),
+        )
+    except MailerError as exc:
+        conn.rollback()
+        raise DeliveryFailed(str(exc)) from exc
+    conn.commit()
 
 
 def verify(conn: psycopg.Connection, email: str, code: str) -> tuple[Account, bool]:
diff --git a/backend/app/main.py b/backend/app/main.py
index 84a43aa..c2c0c69 100644
--- a/backend/app/main.py
+++ b/backend/app/main.py
@@ -11,11 +11,13 @@ from __future__ import annotations
 import logging
 import sys
 from contextlib import asynccontextmanager
+from pathlib import Path
 from typing import Any
 
 import psycopg
 from fastapi import Depends, FastAPI, Response
 from fastapi.responses import JSONResponse
+from fastapi.staticfiles import StaticFiles
 from pydantic import BaseModel
 
 from app.domains import accounts, storefronts
@@ -26,6 +28,15 @@ from app.platform.mailer import Mailer
 from app.platform import session as session_mod
 
 
+# The repo-root VERSION file is the single version source: the deploy pin checks out its
+# tag, and /healthz must report it back (flotilla-core's verify gate compares them).
+_REPO_ROOT = Path(__file__).resolve().parents[2]
+try:
+    _APP_VERSION = (_REPO_ROOT / "VERSION").read_text().strip()
+except OSError:
+    _APP_VERSION = "0.0.0"
+
+
 class RequestCodeBody(BaseModel):
     email: str
 
@@ -79,7 +90,7 @@ def _set_session_cookie(response: Response, account: accounts.Account) -> None:
     )
 
 
-def create_app(database_url: str | None = None) -> FastAPI:
+def create_app(database_url: str | None = None, static_dir: str | Path | None = None) -> FastAPI:
     _ensure_app_logging()
     dsn = database_url or config.database_url()
 
@@ -94,7 +105,7 @@ def create_app(database_url: str | None = None) -> FastAPI:
         finally:
             app.state.pool.close()
 
-    app = FastAPI(title="ecomm", version="0.3", lifespan=lifespan)
+    app = FastAPI(title="ecomm", version=_APP_VERSION, lifespan=lifespan)
 
     @app.get("/healthz")
     def healthz(response: Response, conn: psycopg.Connection = Depends(get_conn)):
@@ -108,7 +119,7 @@ def create_app(database_url: str | None = None) -> FastAPI:
         if pending:
             response.status_code = 503
             return {"status": "unavailable", "reason": "migrations_pending"}
-        return {"status": "ok"}
+        return {"status": "ok", "version": _APP_VERSION}
 
     @app.post("/api/auth/request-code")
     def request_code(
@@ -127,6 +138,11 @@ def create_app(database_url: str | None = None) -> FastAPI:
                 f"Please wait {exc.retry_after_s}s before requesting another code.",
                 retry_after_s=exc.retry_after_s,
             )
+        except accounts.DeliveryFailed:
+            return _error(
+                502, "delivery_failed",
+                "We couldn't send the code — try again in a moment.",
+            )
         return Response(status_code=204)
 
     @app.post("/api/auth/verify")
@@ -192,6 +208,13 @@ def create_app(database_url: str | None = None) -> FastAPI:
             )
         return JSONResponse(status_code=201, content={"id": sf.id, "name": sf.name})
 
+    # Deployed topology (launch-app SPEC §2): nginx proxies everything here, so the
+    # backend serves the built SPA. Mounted LAST so /healthz and /api/* win. In dev the
+    # dist dir doesn't exist (Vite serves the frontend) and the mount is skipped.
+    spa_dir = Path(static_dir) if static_dir is not None else _REPO_ROOT / "frontend" / "dist"
+    if (spa_dir / "index.html").is_file():
+        app.mount("/", StaticFiles(directory=spa_dir, html=True), name="spa")
+
     return app
 
 
diff --git a/backend/app/platform/config.py b/backend/app/platform/config.py
index 70eae74..70251e7 100644
--- a/backend/app/platform/config.py
+++ b/backend/app/platform/config.py
@@ -36,5 +36,35 @@ def cookie_secure() -> bool:
 
 
 def mailer_kind() -> str:
-    """Which mailer adapter to build: 'log' (dev/tests) or 'smtp' (deployed; SLICE-4)."""
+    """Which mailer adapter to build: 'log' (dev/tests) or 'smtp' (deployed)."""
     return os.environ.get("ECOMM_MAILER") or "log"
+
+
+# SMTP relay coordinates (deployed envs only; INV-8 — host/port/user/from are non-secret
+# overlay values, the password is a Secret Manager reference resolved by the deploy).
+
+
+def smtp_host() -> str:
+    return os.environ.get("ECOMM_SMTP_HOST", "")
+
+
+def smtp_port() -> int:
+    return int(os.environ.get("ECOMM_SMTP_PORT") or "587")
+
+
+def smtp_user() -> str:
+    return os.environ.get("ECOMM_SMTP_USER", "")
+
+
+def smtp_password() -> str:
+    return os.environ.get("ECOMM_SMTP_PASSWORD", "")
+
+
+def smtp_from() -> str:
+    """The From header; defaults to the relay user."""
+    return os.environ.get("ECOMM_SMTP_FROM") or smtp_user()
+
+
+def smtp_starttls() -> bool:
+    """STARTTLS on the relay connection (default on; disable only for odd relays)."""
+    return os.environ.get("ECOMM_SMTP_STARTTLS", "1").strip().lower() not in {"0", "false", "no", "off"}
diff --git a/backend/app/platform/mailer.py b/backend/app/platform/mailer.py
index f38eb66..92dae36 100644
--- a/backend/app/platform/mailer.py
+++ b/backend/app/platform/mailer.py
@@ -2,20 +2,30 @@
 
 A one-method port `send(to, subject, body)` with two adapters: `LogMailer` (dev/tests —
 the message lands in the app log and an in-memory outbox tests read back, §6.8) and the
-deployed `SmtpMailer` (SLICE-4). The adapter is chosen by configuration at startup
-(INV-8), so no deployment shape lives in the domain. LogMailer logs the full body on
-purpose: that is PUC-10's "local dev channel" — the one-time code reaches the developer in
-the terminal. The deployed mailer (SLICE-4) will NOT log the body (INV-3 / §6.6 log hygiene).
+deployed `SmtpMailer` (relay coordinates from configuration, INV-8). The adapter is chosen
+by configuration at startup, so no deployment shape lives in the domain. LogMailer logs the
+full body on purpose: that is PUC-10's "local dev channel" — the one-time code reaches the
+developer in the terminal. SmtpMailer never logs the body or the recipient (INV-3 / §6.6
+log hygiene) and raises MailerError on delivery failure (INV-9 → the §6.4 502).
 """
 from __future__ import annotations
 
+import hashlib
 import logging
+import smtplib
 from dataclasses import dataclass
+from email.message import EmailMessage
 from typing import Protocol
 
+from app.platform import config
+
 logger = logging.getLogger("ecomm.mailer")
 
 
+class MailerError(Exception):
+    """Delivery failed — the relay refused or was unreachable (INV-9)."""
+
+
 @dataclass(frozen=True)
 class SentMessage:
     to: str
@@ -41,10 +51,48 @@ class LogMailer:
         logger.info("LogMailer -> %s | %s\n%s", to, subject, body)
 
 
+class SmtpMailer:
+    """Deployed adapter: real mail over an SMTP relay (STARTTLS + login by default).
+
+    Logs only a hashed recipient — never the address, subject, or body (§6.6).
+    """
+
+    def __init__(self, host: str, port: int, user: str, password: str, sender: str, starttls: bool) -> None:
+        self._host, self._port = host, port
+        self._user, self._password = user, password
+        self._sender, self._starttls = sender, starttls
+
+    def send(self, to: str, subject: str, body: str) -> None:
+        msg = EmailMessage()
+        msg["To"] = to
+        msg["From"] = self._sender
+        msg["Subject"] = subject
+        msg.set_content(body)
+        to_hash = hashlib.sha256(to.encode("utf-8")).hexdigest()[:8]
+        try:
+            with smtplib.SMTP(self._host, self._port, timeout=10) as smtp:
+                if self._starttls:
+                    smtp.starttls()
+                if self._user:
+                    smtp.login(self._user, self._password)
+                smtp.send_message(msg)
+        except Exception as exc:
+            logger.warning("smtp send FAILED to=%s: %s", to_hash, type(exc).__name__)
+            raise MailerError(str(exc)) from exc
+        logger.info("smtp sent to=%s", to_hash)
+
+
 def build_mailer(kind: str) -> Mailer:
     """Select the mailer adapter by configured kind (config.mailer_kind(), INV-8)."""
     if kind == "log":
         return LogMailer()
     if kind == "smtp":
-        raise NotImplementedError("SmtpMailer arrives in SLICE-4 (deployed environments)")
+        return SmtpMailer(
+            host=config.smtp_host(),
+            port=config.smtp_port(),
+            user=config.smtp_user(),
+            password=config.smtp_password(),
+            sender=config.smtp_from(),
+            starttls=config.smtp_starttls(),
+        )
     raise ValueError(f"unknown mailer kind: {kind!r}")
diff --git a/backend/tests/test_accounts_request_code.py b/backend/tests/test_accounts_request_code.py
index e7ac722..34a1b9d 100644
--- a/backend/tests/test_accounts_request_code.py
+++ b/backend/tests/test_accounts_request_code.py
@@ -64,3 +64,28 @@ def test_request_code_rejects_invalid_email(conn):
     with pytest.raises(accounts.InvalidEmail):
         accounts.request_code(conn, m, "not-an-email")
     assert m.outbox == []
+
+
+class _FailingMailer:
+    """A mailer whose relay always refuses — the INV-9 honest-failure path."""
+
+    def send(self, to: str, subject: str, body: str) -> None:
+        raise mailer.MailerError("relay refused")
+
+
+def test_delivery_failure_leaves_no_orphan_code(conn):
+    # ecomm#7: send happens BEFORE commit — a failed delivery must not strand an
+    # auth_code row (which would also trip the resend cooldown for 60s).
+    with pytest.raises(accounts.DeliveryFailed):
+        accounts.request_code(conn, _FailingMailer(), "merchant@example.com")
+    rows = conn.execute("SELECT count(*) FROM auth_code").fetchone()[0]
+    assert rows == 0
+
+
+def test_delivery_failure_does_not_trip_cooldown(conn):
+    with pytest.raises(accounts.DeliveryFailed):
+        accounts.request_code(conn, _FailingMailer(), "merchant@example.com")
+    # the immediate retry (relay back up) succeeds — no ResendCooldown
+    m = mailer.LogMailer()
+    accounts.request_code(conn, m, "merchant@example.com")
+    assert len(m.outbox) == 1
diff --git a/backend/tests/test_auth_endpoints.py b/backend/tests/test_auth_endpoints.py
index 1766fd5..aaea47c 100644
--- a/backend/tests/test_auth_endpoints.py
+++ b/backend/tests/test_auth_endpoints.py
@@ -128,3 +128,19 @@ def test_puc_09_logout_clears_session(fresh_db_url):
         # after logout the cookie is cleared -> /me is unauthenticated again
         client.cookies.clear()
         assert client.get("/api/auth/me").status_code == 401
+
+
+def test_request_code_delivery_failure_is_502(fresh_db_url, monkeypatch):
+    # INV-9 honest failure over HTTP (§6.4): the relay refused -> 502 delivery_failed,
+    # never a fake 204. Force the app's mailer to fail after startup.
+    from app.platform import mailer as mailer_mod
+
+    class _FailingMailer:
+        def send(self, to, subject, body):
+            raise mailer_mod.MailerError("relay refused")
+
+    with _client(fresh_db_url) as client:
+        client.app.state.mailer = _FailingMailer()
+        resp = client.post("/api/auth/request-code", json={"email": "merchant@example.com"})
+    assert resp.status_code == 502
+    assert resp.json()["error"]["code"] == "delivery_failed"
diff --git a/backend/tests/test_bootstrap.py b/backend/tests/test_bootstrap.py
index 19ffac6..ec1db53 100644
--- a/backend/tests/test_bootstrap.py
+++ b/backend/tests/test_bootstrap.py
@@ -12,7 +12,7 @@ def test_inv_1_bootstrap_whole_flow_from_empty(fresh_db_url):
     # fresh_db_url is a brand-new empty database; create_app() self-migrates (INV-7).
     with TestClient(create_app(database_url=fresh_db_url)) as client:
         # a fresh deployment serves healthz green before any row exists
-        assert client.get("/healthz").json() == {"status": "ok"}
+        assert client.get("/healthz").json()["status"] == "ok"
 
         # PUC-2: first visitor requests a code; it reaches them via the dev channel
         assert client.post(
diff --git a/backend/tests/test_healthz.py b/backend/tests/test_healthz.py
index 0dc58ba..c0a8871 100644
--- a/backend/tests/test_healthz.py
+++ b/backend/tests/test_healthz.py
@@ -1,14 +1,20 @@
+from pathlib import Path
+
 from fastapi.testclient import TestClient
 
 from app.main import create_app
 
+# /healthz reports the VERSION file's value — the flotilla deploy gate compares
+# body.version against the pinned target (flotilla-core SPEC §8.1 phase 8).
+_VERSION = (Path(__file__).resolve().parents[2] / "VERSION").read_text().strip()
+
 
 def test_healthz_ok_on_migrated_empty_db(fresh_db_url):
     app = create_app(database_url=fresh_db_url)
     with TestClient(app) as client:
         resp = client.get("/healthz")
     assert resp.status_code == 200
-    assert resp.json() == {"status": "ok"}
+    assert resp.json() == {"status": "ok", "version": _VERSION}
 
 
 def test_startup_migrates_from_empty(fresh_db_url):
diff --git a/backend/tests/test_mailer.py b/backend/tests/test_mailer.py
index 961bd4e..7eee087 100644
--- a/backend/tests/test_mailer.py
+++ b/backend/tests/test_mailer.py
@@ -17,10 +17,95 @@ def test_build_mailer_log_kind():
     assert isinstance(m, mailer.LogMailer)
 
 
-def test_build_mailer_smtp_not_yet_available():
-    # SmtpMailer lands in SLICE-4; until then asking for it is an explicit error, not a
-    # silent fallback to LogMailer (which would send no real mail in a deployed env).
+class _FakeSMTP:
+    """Stand-in for smtplib.SMTP capturing the call sequence (no network)."""
+
+    instances: list["_FakeSMTP"] = []
+    fail_on_send = False
+
+    def __init__(self, host, port, timeout=None):
+        self.host, self.port, self.timeout = host, port, timeout
+        self.calls: list[str] = []
+        self.message = None
+        _FakeSMTP.instances.append(self)
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *exc):
+        return False
+
+    def starttls(self):
+        self.calls.append("starttls")
+
+    def login(self, user, password):
+        self.calls.append(f"login:{user}")
+
+    def send_message(self, msg):
+        if _FakeSMTP.fail_on_send:
+            raise RuntimeError("relay refused")
+        self.calls.append("send_message")
+        self.message = msg
+
+
+def _smtp_env(monkeypatch):
+    monkeypatch.setattr(mailer.smtplib, "SMTP", _FakeSMTP)
+    _FakeSMTP.instances.clear()
+    _FakeSMTP.fail_on_send = False
+    monkeypatch.setenv("ECOMM_SMTP_HOST", "smtp.example.com")
+    monkeypatch.setenv("ECOMM_SMTP_PORT", "587")
+    monkeypatch.setenv("ECOMM_SMTP_USER", "sender@example.com")
+    monkeypatch.setenv("ECOMM_SMTP_PASSWORD", "not-a-real-password")
+    monkeypatch.setenv("ECOMM_SMTP_FROM", "ecomm <sender@example.com>")
+
+
+def test_build_mailer_smtp_builds_from_config(monkeypatch):
+    _smtp_env(monkeypatch)
+    m = mailer.build_mailer("smtp")
+    assert isinstance(m, mailer.SmtpMailer)
+
+
+def test_smtpmailer_sends_via_starttls_login(monkeypatch):
+    _smtp_env(monkeypatch)
+    m = mailer.build_mailer("smtp")
+    m.send("merchant@example.com", "Your ecomm code: 123456", "Code: 123456")
+    smtp = _FakeSMTP.instances[-1]
+    assert (smtp.host, smtp.port) == ("smtp.example.com", 587)
+    assert smtp.calls == ["starttls", "login:sender@example.com", "send_message"]
+    assert smtp.message["To"] == "merchant@example.com"
+    assert smtp.message["Subject"] == "Your ecomm code: 123456"
+    assert smtp.message["From"] == "ecomm <sender@example.com>"
+    assert "123456" in smtp.message.get_content()
+
+
+def test_smtpmailer_failure_raises_mailer_error(monkeypatch):
+    _smtp_env(monkeypatch)
+    _FakeSMTP.fail_on_send = True
     import pytest
 
-    with pytest.raises(NotImplementedError):
-        mailer.build_mailer("smtp")
+    m = mailer.build_mailer("smtp")
+    with pytest.raises(mailer.MailerError):
+        m.send("merchant@example.com", "subject", "body")
+
+
+def test_smtpmailer_never_logs_the_body(monkeypatch):
+    # §6.6 log hygiene: codes never appear in deployed logs. LogMailer logging the body
+    # is dev-only by configuration; the deployed adapter must not. The handler attaches
+    # directly to the ecomm.mailer logger (it doesn't propagate to root).
+    import logging
+
+    _smtp_env(monkeypatch)
+    records: list[str] = []
+    handler = logging.Handler()
+    handler.emit = lambda r: records.append(r.getMessage())  # type: ignore[method-assign]
+    lg = logging.getLogger("ecomm.mailer")
+    lg.addHandler(handler)
+    lg.setLevel(logging.DEBUG)
+    try:
+        mailer.build_mailer("smtp").send(
+            "merchant@example.com", "Your ecomm code: 123456", "Code: 123456"
+        )
+    finally:
+        lg.removeHandler(handler)
+    assert records, "the deployed adapter should log the send event (observability §6.6)"
+    assert all("123456" not in r and "merchant@example.com" not in r for r in records)
diff --git a/backend/tests/test_static_spa.py b/backend/tests/test_static_spa.py
new file mode 100644
index 0000000..e07a643
--- /dev/null
+++ b/backend/tests/test_static_spa.py
@@ -0,0 +1,24 @@
+"""Deployed topology (launch-app SPEC §2): nginx proxies EVERYTHING to the backend, so
+the backend must serve the built SPA (frontend/dist) itself. Dev is unaffected — Vite
+serves the frontend and the default dist dir simply doesn't exist."""
+from fastapi.testclient import TestClient
+
+from app.main import create_app
+
+
+def test_spa_served_when_dist_present(fresh_db_url, tmp_path):
+    (tmp_path / "index.html").write_text("<!doctype html><title>ecomm spa</title>")
+    with TestClient(create_app(database_url=fresh_db_url, static_dir=tmp_path)) as client:
+        root = client.get("/")
+        assert root.status_code == 200
+        assert "ecomm spa" in root.text
+        # API + health still win over the mount
+        assert client.get("/healthz").json()["status"] == "ok"
+        assert client.get("/api/auth/me").status_code == 401
+
+
+def test_no_mount_when_dist_absent(fresh_db_url, tmp_path):
+    # An empty/missing dist (the dev case) must not 500 the app — / just 404s.
+    with TestClient(create_app(database_url=fresh_db_url, static_dir=tmp_path / "nope")) as client:
+        assert client.get("/").status_code == 404
+        assert client.get("/healthz").json()["status"] == "ok"
diff --git a/docs/BOOTSTRAP.md b/docs/BOOTSTRAP.md
index 0d0c503..cd0d7c7 100644
--- a/docs/BOOTSTRAP.md
+++ b/docs/BOOTSTRAP.md
@@ -4,8 +4,9 @@ Bringing an environment from **empty persistence** to "first merchant, first
 storefront" through the product flows alone (SD-0001 BUC-5). Empty is a working state
 (INV-1): the app applies its own schema migrations at startup; there is no seed step.
 
-This document grows per environment. SLICE-1 ships the **localhost** section; the
-pre-production and production sections land with SLICE-4.
+This document grows per environment. SLICE-1 shipped the **localhost** section;
+SLICE-4 adds **pre-production (PPE)**. The production section lands with the prod
+stand-up.
 
 ## Localhost
 
@@ -61,4 +62,67 @@ environment starts from (BUC-5a).
 `scripts/dev.sh` sets `ECOMM_DATABASE_URL` to the local compose DSN
 (`postgresql://ecomm:ecomm@localhost:5432/ecomm`). No deployment shape is baked into
 the app (INV-8); deployed environments supply this and other config from Secret
-Manager (SLICE-4).
+Manager (see PPE below).
+
+## Pre-production (PPE)
+
+PPE is stood up and deployed through the **launch-app / flotilla-core** suite only
+(handbook §8.5 — provisioning is an operator-run gesture). The app's deployment
+record is `deployment.toml` at this repo's root; flotilla-core consumes it.
+
+### One-time provisioning (operator-run, in order)
+
+1. **Cloud foundation** — `scaffold-gcp-project`: the GCP project, its dedicated
+   `--no-activate` gcloud config, billing, core APIs, ADC quota pin.
+2. **Managed database** — `provision-datastore` (launch-app §6.6a, built for ecomm's
+   D-7/D-8): Cloud SQL for PostgreSQL 16, private-IP-only, automated backups +
+   point-in-time recovery; writes the full DSN to Secret Manager as
+   `<project>/ecomm-ppe-database-url`. Bound on the deployment record as
+   `ECOMM_DATABASE_URL`.
+3. **Secrets** (references only — bytes go in via stdin, never through a session):
+   `ECOMM_SESSION_SECRET` (fresh random), `ECOMM_SMTP_PASSWORD` (the shared
+   Wiggleverse relay credential), and flotilla's own Gitea read token for this
+   private repo.
+4. **VM + edge** — `provision-vm`: the e2-micro, IAP-only SSH, nginx + Cloudflare
+   origin TLS, the systemd unit, DNS for `ecomm-ppe.wiggleverse.org`.
+5. **Deployment record** — `flotilla-core deployment scaffold ecomm … -o
+   deployment.toml`, validate, commit it here, `deployment import --reconcile`.
+
+### Deploy
+
+Each release is a git tag `v<VERSION>` matching the repo-root `VERSION` file (the
+pin). The one gesture, from the flotilla-core repo's venv:
+
+```bash
+CLOUDSDK_ACTIVE_CONFIG_NAME=ecomm .venv/bin/flotilla-core deploy ecomm
+```
+
+Nine phases, fail-stop; it ends by polling `https://ecomm-ppe.wiggleverse.org/healthz`
+and requiring `status == "ok"` and `version == <target>`. Watch it yourself the same
+way:
+
+```bash
+curl https://ecomm-ppe.wiggleverse.org/healthz
+```
+
+### Configuration surface (PPE values)
+
+| Env var | Kind | Value |
+| --- | --- | --- |
+| `ECOMM_DATABASE_URL` | secret ref | `<project>/ecomm-ppe-database-url` (from provision-datastore) |
+| `ECOMM_SESSION_SECRET` | secret ref | `<project>/ecomm-ppe-session-secret` |
+| `ECOMM_SMTP_PASSWORD` | secret ref | the shared Wiggleverse relay credential |
+| `ECOMM_MAILER` | overlay | `smtp` |
+| `ECOMM_COOKIE_SECURE` | overlay | `1` |
+| `ECOMM_SMTP_HOST` / `_PORT` / `_USER` / `_FROM` | overlay | the relay coordinates (non-secret) |
+
+### The rehearsal (PUC-11)
+
+From empty persistence: the deploy migrates the schema at startup (INV-7); then a
+real sign-up → one-time code arriving by **real email** → create storefront → admin,
+through the public flows alone. Record each rehearsal here when it happens.
+
+## Production
+
+Lands with the prod stand-up — the **identical gesture** on a prod deployment record
+(BUC-5a): same provisioning skills, same deploy, same rehearsal.
diff --git a/docs/superpowers/plans/2026-06-10-slice-4-deploy-contract.md b/docs/superpowers/plans/2026-06-10-slice-4-deploy-contract.md
new file mode 100644
index 0000000..1f376ec
--- /dev/null
+++ b/docs/superpowers/plans/2026-06-10-slice-4-deploy-contract.md
@@ -0,0 +1,55 @@
+# SLICE-4 (part 1) — Deploy-Contract Code Implementation Plan
+
+> **For agentic workers:** REQUIRED SUB-SKILL: Use superpowers:subagent-driven-development (recommended) or superpowers:executing-plans to implement this plan task-by-task. Steps use checkbox (`- [ ]`) syntax for tracking.
+
+**Goal:** Make ecomm deployable by flotilla-core's 9-phase gesture and rehearsable on PPE: versioned health, SPA served by the backend, real `SmtpMailer` with honest delivery failure (closes ecomm#7), per SD-0001 §7.2 (SLICE-4) — the code half. Provisioning (Cloud SQL via the new launch-app `provision-datastore`, VM, deployment.toml) and the PPE rehearsal follow as operator gestures in the same session.
+
+**Anchor:** SD-0001 §7.2 SLICE-4 (R2a, checked this session). flotilla contract: flotilla-core SPEC §8.1 (checkout `v<VERSION>` tag → pip → `npm ci && npm run build` → write `backend/.env` → restart → verify `body.version == target && body.status == "ok"`); provision-vm: nginx proxies ALL routes to uvicorn `app.main:app` (WorkingDirectory `backend/`), so the backend must serve `frontend/dist`.
+
+**Architecture:** `VERSION` at repo root is the single version source (healthz body + FastAPI version + the deploy pin). `create_app()` mounts `frontend/dist` (when present) after all API routes — SPA fallback via `StaticFiles(html=True)`. `SmtpMailer` is the second adapter of the existing mailer port (STARTTLS smtplib, config from `ECOMM_SMTP_*`, INV-8); delivery failure raises `MailerError` → `accounts.request_code` sends **before** commit (rollback on failure — no orphan code, no tripped cooldown; ecomm#7) → BFF surfaces `502 delivery_failed` (INV-9).
+
+**Tech Stack:** stdlib `smtplib`/`email.message`; FastAPI `StaticFiles`; no new dependencies.
+
+---
+
+### Task 1: VERSION + versioned /healthz
+
+**Files:** Create `VERSION` (root). Modify `backend/app/main.py`, `backend/tests/test_healthz.py`.
+
+- [ ] Write `VERSION` containing `0.4.0`.
+- [ ] Test first: `test_healthz_ok_on_migrated_empty_db` asserts `{"status": "ok", "version": "0.4.0"}` read from the VERSION file (compare against `(repo_root/"VERSION").read_text().strip()`, not a literal). Run → FAIL.
+- [ ] `main.py`: add `_APP_VERSION = (Path(__file__).resolve().parents[2] / "VERSION").read_text().strip()` (fallback `"0.0.0"` when missing); healthz returns `{"status": "ok", "version": _APP_VERSION}`; `FastAPI(version=_APP_VERSION)`. Run → PASS. Commit.
+
+### Task 2: backend serves the SPA (deploy phase-8 contract)
+
+**Files:** Modify `backend/app/main.py`. Test `backend/tests/test_static_spa.py`.
+
+- [ ] Test first: `create_app(database_url=..., static_dir=tmp_path)` with a `tmp_path/index.html`; GET `/` → 200 + the html; GET `/healthz` and `/api/auth/me` still answer JSON (API wins over the mount). Default `static_dir=None` → resolves `repo_root/frontend/dist`, skipped silently when absent (dev: Vite serves). Run → FAIL.
+- [ ] `create_app(database_url=None, static_dir: str | Path | None = None)`; after the last route: resolve dir, `if dir/index.html exists: app.mount("/", StaticFiles(directory=dir, html=True), name="spa")`. Run → PASS (whole suite). Commit.
+
+### Task 3: SmtpMailer + config surface (INV-8)
+
+**Files:** Modify `backend/app/platform/{mailer,config}.py`. Test `backend/tests/test_mailer.py` (extend).
+
+- [ ] Config additions: `smtp_host()` (`ECOMM_SMTP_HOST`), `smtp_port()` (`ECOMM_SMTP_PORT`, 587), `smtp_user()`, `smtp_password()`, `smtp_from()` (default = user), `smtp_starttls()` (default on).
+- [ ] Tests first: `MailerError` exists; `build_mailer("smtp")` returns `SmtpMailer` wired from env (monkeypatched); `SmtpMailer.send` drives a monkeypatched `smtplib.SMTP` (starttls → login → send_message with To/Subject/From + body) and never logs the body; SMTP exception → `MailerError`. Run → FAIL.
+- [ ] Implement: `MailerError(Exception)`; `SmtpMailer` (EmailMessage; `smtplib.SMTP(host, port, timeout=10)`, STARTTLS per config, login when user set, `send_message`; `except Exception → raise MailerError`; logs only `smtp sent to=<sha256[:8] of recipient>` — §6.6 log hygiene); `build_mailer("smtp")` builds it from config. Run → PASS. Commit.
+
+### Task 4: honest delivery failure — send-before-commit + 502 (closes ecomm#7)
+
+**Files:** Modify `backend/app/domains/accounts/{errors,service,__init__}.py`, `backend/app/main.py`. Test `backend/tests/test_accounts_request_code.py` + `test_auth_endpoints.py` (extend).
+
+- [ ] Tests first: a mailer whose `send` raises `MailerError` → service raises `accounts.DeliveryFailed`, **no `auth_code` row remains**, and an immediate retry is **not** cooldown-blocked; endpoint test: 502 `{"error": {"code": "delivery_failed"}}`. Run → FAIL.
+- [ ] Implement: `DeliveryFailed(AccountsError)`; `request_code` moves `conn.commit()` **after** `mailer.send(...)`, wrapping send in `try/except MailerError → conn.rollback(); raise DeliveryFailed`; BFF maps it to `_error(502, "delivery_failed", "We couldn't send the code — try again.")`. Run → PASS (whole backend suite). Commit.
+
+### Task 5: BOOTSTRAP.md PPE section + housekeeping + gate
+
+**Files:** Modify `docs/BOOTSTRAP.md`, `README.md`, `frontend/package.json` (0.4.0).
+
+- [ ] BOOTSTRAP.md: replace the "land with SLICE-4" sentence; add **Pre-production (PPE)** section — prerequisites (suite-run provisioning: scaffold-gcp-project → provision-datastore (Cloud SQL, engineering#46) → provision-vm → define-deployment/import; secrets as references), the one deploy gesture (`CLOUDSDK_ACTIVE_CONFIG_NAME=<config> flotilla-core deploy <name>`), how to watch `/healthz`, the rehearsal walk (PUC-11), reset-to-empty note; Prod section: placeholder "lands with the prod stand-up" honestly.
+- [ ] README status: deploy contract in place; frontend package 0.4.0.
+- [ ] `./scripts/check.sh` → all green. Commit. Push, PR citing SD-0001 §7.2 SLICE-4 + ecomm#7, merge, **tag `v0.4.0` on the merge commit and push the tag** (the deploy pin).
+
+## Self-review
+
+Spec coverage: SmtpMailer + config wiring INV-8 ✓ (T3), §6.6 hardening — Secure cookies already config-driven, log hygiene ✓ (T3 no-body logging; LogMailer is dev-only by config), `deployment.toml` + provisioning deliberately deferred to the Phase-C suite gestures (needs the GCP project id that scaffold-gcp-project mints), BOOTSTRAP.md PPE ✓ (T5), versioned health for the §8.1 verify ✓ (T1), SPA serving for the §2 topology ✓ (T2), ecomm#7 ✓ (T4). E2E browser tests still deferred per §6.8. Type consistency: `MailerError` lives in platform/mailer; `DeliveryFailed` in accounts errors; both exported via package surfaces.
diff --git a/frontend/package.json b/frontend/package.json
index 11eda0d..4103db0 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -1,7 +1,7 @@
 {
   "name": "wiggleverse-ecomm-frontend",
   "private": true,
-  "version": "0.3.0",
+  "version": "0.4.0",
   "type": "module",
   "scripts": {
     "dev": "vite",