Emit contract events for create/withdraw/pause/resume/cancel/settle in streampay-stream

[greatest0fallt1me]

Description

Publish structured Soroban events for every lifecycle transition so the backend's events indexer and transactional outbox (app/api/streams/events, Horizon events indexer) can track on-chain state changes. Events are the contract's public, indexable record of money movement.

Requirements and Context

• Use env.events().publish(...) with symbol_short! topics for: created, started, withdrawn, paused, resumed, cancelled, settled.
• Include relevant data per event (stream id, sender/recipient, token, amount, timestamp) in the event payload.
• Keep topic symbols <= 9 chars (symbol_short! constraint) and document the event schema for indexers.
• Emit events only after successful state mutation/transfer.
• Must be secure, tested, and documented.
• Should be efficient and easy to review.

Suggested Execution

1. Fork the repo and create a branch

   git checkout -b feature/contract-events

2. Implement changes
   • contracts/contracts/streampay-stream/src/events.rs (typed publish helpers)
   • contracts/contracts/streampay-stream/src/lib.rs (emit on each transition)
   • contracts/contracts/streampay-stream/src/test.rs (assert events via env.events().all())
3. Test and commit
   • cd contracts && cargo test -p streampay-stream events
   • Cover edge cases (no event emitted on failed/rejected call)
   • Include test output and notes in the PR

Example commit message

feat: emit lifecycle events for streams

Acceptance Criteria

• Each lifecycle transition emits exactly one well-formed event
• Event topics use symbol_short! and payloads carry id/amount/timestamp
• Failed/rejected calls emit no event
• cargo test asserts events with env.events().all()

Guidelines

• .rs files under contracts/contracts/streampay-stream/src/; tests via cargo test; NatSpec-style /// docs; minimum 95% test coverage; document the event schema for indexers
• Clear documentation and inline comments
• Timeframe: 96 hours

[dubemoyibe-star]

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Hey can I work on this issue

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