Add trading and broker API gate demo

[safal207]

Goal

Add a fintech-oriented ProofPath demo for trading, broker, and market-operation APIs.

Why this matters

A valid broker API token, trading session, or websocket/API access does not automatically mean a valid financial action.

AI assistants and trading automation can propose actions that are syntactically valid but financially dangerous:

• placing an order outside approved scope;
• changing risk parameters;
• modifying broker account settings;
• triggering production trading action when only market inspection was requested;
• cancelling or replacing orders without approval;
• exporting account-sensitive data.

Core line:

Valid broker API access should not automatically mean valid trading action.

Demo concept

Create examples/trading-broker-gate/ with three safe simulated scenarios:

1. Market/account inspection

   • Example: read-only market/account status.
   • Expected ProofPath decision: ACCEPT.

2. Trade placement without approval

   • Example: production order placement without explicit approval.
   • Expected ProofPath decision: BLOCK.

3. Approved order cancellation or risk-reduction action

   • Example: approved order cancellation or risk-reduction action.
   • Expected ProofPath decision: ACCEPT.

Suggested action scopes

trading.market.read
trading.account.read
trading.order.place
trading.order.cancel
trading.order.replace
trading.position.reduce
trading.risk.modify
trading.account.export

Deliverables

• Add examples/trading-broker-gate/README.md.
• Add read-only inspection scenario.
• Add blocked trade placement scenario.
• Add approved order cancellation/risk-reduction scenario.
• Add expected outputs and audit shape.
• Add row to README execution-boundary demo matrix.

Acceptance criteria

• The demo is simulated and does not connect to a real broker.
• The demo does not provide trading advice.
• The repo does not claim ProofPath replaces broker permissions, exchange controls, user approval, or financial compliance systems.
• The demo clearly separates read-only inspection from high-risk financial actions.

Related

• Prepare ProofPath for external reviewers #32
• Add audit-log verification note and hash-chain checker #50
• Add policy configuration for scopes and approval rules #53