ghcp-webinar

🏦 Ledgerly Payments — the Agent Squad demo

A deliberately buggy legacy Java 17 payments service. All 4 unit tests pass, yet the nightly batch quietly loses money. A squad of Copilot agents finds the bugs, proves them with failing tests, and fixes them, all inside guardrails.

=== Ledgerly Payments - nightly batch ===
1. Invoice 100.00 USD in 3 installments: [33.33, 33.33, 33.33]
   Total we will collect:                 99.99            ← a penny vanished
2. Interest on 1,000,000 @ 5% for 90 days: 0.0              ← integer division
3. Trade on Thu 2026-10-08 settles on Sun 2026-10-11        ← banks are closed on Sunday
4. Payments received: 3, after de-duplication: 3            ← equals() without hashCode()
[FX] key=DEMO-ONLY-… account=4400-1234-5678-9012 …          ← secret + PII in logs

What’s inside

Path	Copilot feature	What it does
.github/copilot-instructions.md	Always-on instructions	Build commands and team conventions
.github/agents/tech-lead.agent.md	Custom agent (coordinator)	Runs subagents in parallel, then fixes code. Has an agent-scoped Stop hook and two handoffs
.github/agents/bug-hunter.agent.md and the other workers	Subagents	Read-only specialists (user-invocable: false)
.github/agents/code-reviewer.agent.md	Handoff target	Independent review. disable-model-invocation: true, so only a human can start it
.github/skills/money-handling/	Agent skill	Banking money rules, plus a script and a reference file loaded only when needed
.github/skills/junit5-tests/	Agent skill	Red-green testing conventions
.github/hooks/audit.json	Hooks	Logs every prompt, tool call and subagent to .github/hooks/logs/, and injects context
.github/hooks/guardrails.json	Hooks	Blocks rm -rf, git push, deploys, and edits to the hooks themselves
.github/hooks/scripts/quality-gate.*	Agent-scoped hook	The Tech Lead can’t finish while mvn test is red

Run it

mvn -q test                                                   # green (that's the problem)
mvn -q compile && java -cp target/classes com.ledgerly.payments.App

Demo it

scripts/setup-demo.sh        # once: git init + tag the baseline
scripts/watch-timeline.sh    # in a side terminal: live agent timeline from the hooks
scripts/reset-demo.sh        # between runs

Then in VS Code Chat, set Session Target → Local, pick the Tech Lead agent, and send:

Get the nightly batch audit-ready.

Windows users: use the .ps1 versions of the scripts. The hooks pick the right one automatically.