Payments Dashboard

AWS SAM application that ingests payment CSVs, syncs check data with Bank of America CashPro APIs, processes Gusto payroll confirmation emails into Slack notifications, surfaces an outstanding-payments dashboard in Slack, and routes expense approvals through a Slack reaction-driven workflow.

Architecture

• ProcessPayrollEmail — Lambda triggered by S3 (inbound email) and SQS (batch timer). SES receives Gusto payroll emails at payroll@int.seahaven.com, stores them to S3, and this Lambda parses the email body, extracts financial data, and posts a combined Slack notification (employee payroll + contractor payments) after a 10-minute batching window. Runs outside VPC.

• ProcessPaymentCsv — Lambda triggered by S3 CSV upload. Parses Stampli payment exports, upserts to DynamoDB, and submits new/cancelled checks to the CashPro Check Management API.

• FetchBoaTransactions — Scheduled Lambda (weekdays 9am ET). Calls the CashPro Previous Day Transaction Inquiry API and matches cleared/returned checks back to DynamoDB records.

• SlackAppHome — Lambda behind API Gateway. Renders the payments dashboard on the Slack App Home tab with outstanding aging buckets and drill-down modals.

• ExpenseReceiver — Lambda behind API Gateway (POST /slack/expense-events). Verifies the Slack signing secret (HMAC-SHA256), handles URL verification challenges, and async-invokes ExpenseProcessor. Runs outside VPC.

• ExpenseProcessor — Async Lambda invoked by ExpenseReceiver. Processes :white_check_mark: reactions to advance expense messages through a four-stage Slack channel pipeline: Submitted → Processed → Authorized → Matched. Runs outside VPC.

ProcessPaymentCsv, FetchBoaTransactions, and SlackAppHome run inside a VPC with a NAT Gateway for a static outbound IP (required by BoA IP whitelisting). ProcessPayrollEmail, ExpenseReceiver, and ExpenseProcessor run outside the VPC.

Expense Approval Bot

Reaction-driven workflow that routes expense submissions through four Slack channels. A separate Slack app ("Expense Approval Bot") posts to a Submitted channel. Users react with ✅ to advance the message to the next stage.

Channel pipeline:

Stage	Channel ID	Action on ✅
Submitted	C0AQ2AWLNEN	Thread reply on original, copy to Processed
Processed	C0APLSGABAB	Delete from Processed, post to Authorized
Authorized	C0AQ09CDJH4	Delete from Authorized, post to Matched
Matched	C0APYUM1JFP	Terminal stage (no further routing)

Architecture: Two Lambdas — ExpenseReceiver (HTTP endpoint, signature verification, async invoke) and ExpenseProcessor (business logic). This is the same receiver/processor pattern used for Slack's 3-second timeout requirement.

Secrets (Secrets Manager):

Secret	Purpose
payments-dashboard/expense-slack-token	Slack Bot token for the Expense Approval Bot app
payments-dashboard/expense-slack-signing-secret	Slack signing secret for request verification

Payroll Email Pipeline

Gusto sends payroll confirmation emails when payroll is run. A Gmail filter on adam@seahavenind.com auto-forwards emails from automated@gusto.com and gustonoreply@gusto.com to payroll@int.seahaven.com.

Flow: Gmail forward → SES receipt rule → S3 bucket → Lambda parses email → DynamoDB (pending) → SQS delay queue (10 min) → Lambda batches all pending items for that date → single Slack message → DynamoDB (notified)

Deduplication: Each email is deduplicated by DynamoDB key (PAYROLL_EMAIL#employee#<date> or PAYROLL_EMAIL#contractor#<date>#<bank-suffix>). The batch post is deduplicated by PAYROLL_BATCH#<date>. All items have a 90-day TTL.

BoA CashPro API Integration

Two separate CashPro APIs are used, each with its own OAuth credentials:

API	Purpose	Endpoint
Check Management	Issue and cancel checks	/cashpro/checkmanagement/v1/check-issues
Reporting (Transaction Inquiry)	Fetch previous-day transactions	/cashpro/reporting/v1/transaction-inquiries/previous-day

Authentication flow:

1. POST to /authn/v1/client-authentication with applicationID, client_id, and client_secret
2. Receive a Bearer access_token (valid 1 hour)
3. Pass the token in the Authorization header for subsequent API calls

Base URLs:

• Production: https://api.bofa.com
• Sandbox: https://api-sb.bofa.com

Secrets

All BoA and Slack credentials are stored in AWS Secrets Manager (per engineering-handbook/secrets-and-config.md). The Slack token is a plaintext secret; the two BoA secrets are JSON grouping each API's credentials:

Secret	Type	Contents
payments-dashboard/slack-bot-token	plaintext	Slack Bot OAuth token (used by processPayrollEmail, slackAppHome)
payments-dashboard/boa-check-mgmt	JSON	appId, clientId, token, accountNumber, companyId — Check Management API (processPaymentCsv)
payments-dashboard/boa-reporting	JSON	appId, clientId, token, accountNumber, bankId — Reporting API (fetchBoaTransactions)

boa-account-number is duplicated into both BoA secrets. Each Lambda is granted secretsmanager:GetSecretValue scoped to only the secret it needs. The Expense Approval Bot uses two additional secrets (payments-dashboard/expense-slack-token, payments-dashboard/expense-slack-signing-secret).

Scripts

Script	Purpose
scripts/test-boa-sandbox.js	One-off sandbox connectivity test for both CashPro APIs
scripts/seed-from-csv.js	Seed DynamoDB from a local CSV file
scripts/seed-bank-status.js	Seed bank clear status data into DynamoDB

Deployment

sam build
sam deploy --guided

The BOA_BASE_URL environment variable in template.yaml controls whether Lambdas hit production (https://api.bofa.com) or sandbox (https://api-sb.bofa.com). All other BoA config is read from Secrets Manager at runtime.