Email Settings

1. Architecture chosen
Manager pushes environment variables into every business's .env, rather than businesses fetching config at runtime. Manager has no database of its own today (confirmed via code — no Prisma, no ORM dependency anywhere in manager/); every piece of its state is either an env var or a flat file under STACKS_DIR. A "runtime shared-config source" design would make every single email send (including OTP login) depend on Manager being reachable — a new failure mode this app has never had, for no real benefit. Instead:

Storage: one JSON file, stacks/manager/global-settings.json (gitignored), shaped for future sections (SMS, storage, backups, branding...) to slot in as sibling keys.
Secret at rest: the SMTP password is AES-256-GCM encrypted with a new MANAGER_SETTINGS_ENCRYPTION_KEY, never returned to the browser.
Rollout: saving complete settings automatically pushes the 7 EMAIL_* keys into every business's .env via the exact same surgical upsertEnvValues helper updateBusiness() already uses for name/domain edits, then force-recreates each container (composeUp(dir, {forceRecreate:true})) — the identical mechanism that already applies domain changes today.
New businesses get the current global settings baked into their .env at provisioning time — no manual step, ever.

2. Files changed
New (Manager): global-settings.ts (storage+encryption), email-rollout.ts (push-to-all-businesses), test-email.ts (standalone nodemailer test-send), dashboard/settings/ (page.tsx, actions.ts, email-settings-form.tsx).

Modified (Manager): compose-template.ts (optional email block in generated .env), provisioning.ts (reads global settings at creation), dashboard/layout.tsx (Settings nav link), package.json/package-lock.json (added nodemailer).

Modified (main app): brevo-email-provider.ts (added encryption mode + replyTo, backward-compatible), its test file (8 new tests).

Modified (docs): root .gitignore, .env.example, .env.business.example, manager/.env.example.

3. New volumes/databases/config files
None — no new Docker volume, no database. One new gitignored file, stacks/manager/global-settings.json, living inside the STACKS_DIR bind-mount Manager already has.

4. New environment variables
MANAGER_SETTINGS_ENCRYPTION_KEY (Manager only, required to use Settings) — 32-byte hex, generate with openssl rand -hex 32.
EMAIL_SMTP_ENCRYPTION and EMAIL_REPLY_TO (main app, both optional) — unset EMAIL_SMTP_ENCRYPTION preserves today's exact port-based inference, so existing deployments are unaffected.
Reply-to is now business-specific with global fallback,

5. How settings are persisted
stacks/manager/global-settings.json, written by saveEmailSettings(). The password is encrypted before writing; every other field is plain text (host, port, username, from-address, from-name, reply-to, encryption mode, last-test result) since none of those are secrets.

6. How business containers receive global settings
Via their own .env file (Docker Compose's env_file:, unchanged mechanism) — Manager writes the 7 EMAIL_* keys into it and recreates the container. Nothing in the business app itself needed a new runtime dependency; getEmailProvider() still just reads process.env once at process start, exactly as before.

7. What happens to existing businesses when settings change
Saving complete settings (host+username+password+from-address all present) automatically loops every business, updates its .env, and force-recreates its container in one action — the UI reports "applied to N of M businesses" with per-business failure reasons. A separate "Reapply to all businesses" button retries this without re-entering anything, for recovering from a business that was down during the last save. Saving incomplete settings persists them as a draft and touches no business (verified live — this is what stops a business from being flipped into a broken "brevo with blank credentials" state).

8. Manual deployment/update steps on the VPS
Generate a key: openssl rand -hex 32, add it as MANAGER_SETTINGS_ENCRYPTION_KEY to stacks/manager/.env.
Rebuild/redeploy the Manager image and the main app image (both changed) as usual.
Open Manager → Settings, fill in real SMTP details, send a test email, then Save — this rolls out to every existing business automatically. Nothing else needs to run by hand.

9. Security considerations
Password never logged, never returned to the browser after save (only a hasPassword boolean) — confirmed live: the form re-shows a masked placeholder, not the real value.
Test-email errors are categorized (auth/connection/timeout) before display — the raw SMTP error is never forwarded.
Encrypted at rest with AES-256-GCM; losing/rotating the key makes the stored password undecryptable (documented in manager/.env.example).
Settings routes sit under manager/src/proxy.ts's existing auth gate — no new auth surface.
Validated before rollout: malformed addresses/ports are rejected before Save, and rollout only fires when configuration is actually complete.

On JSON vs. database for Manager: JSON is the right call here. Reasoning:

Manager has zero DB dependencies today, deliberately — its own package.json description says an earlier attempt at giving it business-data access "repeatedly broke." Introducing SQLite/Prisma just for one settings blob breaks that design principle for not much gain.

The access pattern is a poor fit for a DB anyway: read on page-load/provisioning/rollout, written by a human clicking Save occasionally. No queries, no joins, no need for transactions beyond "read-modify-write one small file."

Reconsider if: multiple admins need to edit concurrently with conflict detection, you want an audit history of who-changed-what-when beyond "last test result," or the settings graph grows relational (e.g., per-business overrides tied by foreign key to businesses) rather than a flat global blob. None of that applies yet.

manager/src/lib/email-rollout.ts

@@ -0,0 +1,74 @@
+import path from "node:path";
+import { composeUp } from "./docker";
+import { readEnvFile, readEnvValue, upsertEnvValues } from "./env-file";
+import type { ResolvedEmailSettings } from "./global-settings";
+import { listBusinessStacks, stackDir } from "./stacks";
+
+export interface EmailRolloutResult {
+  slug: string;
+  ok: boolean;
+  error?: string;
+}
+
+/**
+ * Pushes global email settings into every business's own `.env` (the
+ * same surgical, non-destructive `upsertEnvValues` helper
+ * provisioning.ts's own updateBusiness already uses for name/domain
+ * edits — never a full-file regenerate, so nothing else hand-edited into
+ * a business's .env is touched), then force-recreates its container so
+ * the change actually takes effect — a container only reads its `.env`
+ * at creation (see docker.ts's composeUp), the same reason
+ * updateBusiness recreates on a domain change.
+ *
+ * EMAIL_REPLY_TO is deliberately excluded from the "always overwrite"
+ * set: unlike the SMTP transport itself (host/credentials/from-address),
+ * a reply-to address is something a business plausibly wants to be its
+ * own (e.g. its own support inbox) rather than a platform-wide value.
+ * The global setting is only ever applied as a *fallback* — written the
+ * first time (a fresh business's .env has it blank), left untouched
+ * forever after a business (or a human editing its .env by hand) sets
+ * its own. This mirrors updateBusiness()'s own "never clobber anything
+ * hand-edited since provisioning" rule.
+ *
+ * Runs sequentially, not in parallel: this is an infrequent admin action
+ * on a single-VPS, modest-business-count deployment, and sequential
+ * keeps one slow/failing business from making the Docker daemon/MySQL
+ * connection pool contend with N simultaneous `docker compose up`s. A
+ * per-business result is returned so a partial failure (one business's
+ * container already down, a stack in a broken state, etc.) is visible
+ * rather than silently swallowed — the caller can offer a "Reapply"
+ * action that just calls this again.
+ */
+export async function applyEmailSettingsToAllBusinesses(settings: ResolvedEmailSettings): Promise<EmailRolloutResult[]> {
+  const businesses = await listBusinessStacks();
+  const results: EmailRolloutResult[] = [];
+
+  for (const business of businesses) {
+    try {
+      const dir = stackDir(business.slug);
+      const envPath = path.join(dir, ".env");
+
+      const currentEnv = await readEnvFile(envPath);
+      const currentReplyTo = currentEnv ? readEnvValue(currentEnv, "EMAIL_REPLY_TO") : null;
+      const businessHasOwnReplyTo = Boolean(currentReplyTo && currentReplyTo.trim());
+
+      await upsertEnvValues(envPath, {
+        EMAIL_PROVIDER: "brevo",
+        EMAIL_SMTP_HOST: settings.host,
+        EMAIL_SMTP_PORT: String(settings.port),
+        EMAIL_SMTP_USERNAME: settings.username,
+        EMAIL_SMTP_PASSWORD: settings.password,
+        EMAIL_SMTP_ENCRYPTION: settings.encryption,
+        EMAIL_FROM_ADDRESS: settings.fromAddress,
+        EMAIL_FROM_NAME: settings.fromName,
+        ...(businessHasOwnReplyTo ? {} : { EMAIL_REPLY_TO: settings.replyTo }),
+      });
+      await composeUp(dir, { forceRecreate: true });
+      results.push({ slug: business.slug, ok: true });
+    } catch (error) {
+      results.push({ slug: business.slug, ok: false, error: error instanceof Error ? error.message : String(error) });
+    }
+  }
+
+  return results;
+}