feat(contracts): emit dedicated ProtocolPaused events on pause toggle…

[timiturn3r]

Description

This pull request introduces dedicated Soroban contract events when toggling emergency protocol pause state in stream_contract. Previously, setting or clearing the protocol pause state updated storage without emitting a dedicated standard event subscribed to by external indexers and monitoring agents.

With this change:

• A new event struct ProtocolPausedEvent and helper function emit_protocol_paused have been introduced in events.rs.
• Events are emitted with topics ["FlowFi", "ProtocolPaused"] and contain the caller/admin address and boolean pause state (is_paused).
• set_protocol_pause invokes emit_protocol_paused, and an alias entrypoint set_emergency_pause has been exposed in lib.rs.
• Comprehensive unit tests have been added to verify that pausing and unpausing emit the expected topics and payloads.

Type of Change

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📚 Documentation update
• 🔧 Refactoring (no functional changes)
• ⚡ Performance improvement
• 🧪 Test addition or update

Related Issues

Closes #1517

Changes Made

• Defined Event Payload and Helper Function (contracts/stream_contract/src/events.rs):
  • Added ProtocolPausedEvent contract type with admin: Address and is_paused: bool.
  • Implemented emit_protocol_paused(env: &Env, admin: &Address, is_paused: bool) publishing under topics (Symbol::new(env, "FlowFi"), Symbol::new(env, "ProtocolPaused")).
• Integrated Emission in Contract Entrypoints (contracts/stream_contract/src/lib.rs):
  • Invoked emit_protocol_paused(&env, &caller, paused) inside set_protocol_pause.
  • Added public set_emergency_pause(env: Env, admin: Address, paused: bool) -> Result<(), StreamError> entrypoint delegating to set_protocol_pause.
  • Preserved existing protocol_pause_status event for backward compatibility.
• Added Unit Test Assertions (contracts/stream_contract/src/test.rs):
  • Added test_protocol_pause_and_unpause_emit_dedicated_event testing both pause (is_paused: true) and unpause (is_paused: false) via set_protocol_pause.
  • Added test_set_emergency_pause_emits_dedicated_event validating event emission via set_emergency_pause.
• Aligned Storage and Error Surface:
  • Synchronized STREAM_FIELD_COUNT = 17 in storage.rs matching current Stream fields.
  • Added missing variants (StreamStillActive, StreamNotActive, ArithmeticOverflow) to StreamError.

Testing

Test Coverage

• Unit tests added/updated
• Integration tests added/updated
• Manual testing performed

Test Steps

1. Navigate to contracts/:

   cd contracts

2. Run the newly added pause event test suite:

   cargo test test_protocol_pause_and_unpause_emit_dedicated_event
   cargo test test_set_emergency_pause_emits_dedicated_event

3. Run the complete test suite, formatting, and linting checks:

   cargo test
   cargo fmt --all -- --check
   cargo clippy --all-targets -- -D warnings

Breaking Changes

None. Existing storage layouts and entrypoints are preserved, and the existing protocol_pause_status event remains published alongside the new dedicated event.

Screenshots/Demo

N/A (Smart Contract backend changes)

Checklist

• My code follows the project's style guidelines
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• Updated Postman/Hoppscotch API collections if routes changed
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published
• I have checked for breaking changes and documented them if applicable
• If this change adds or modifies a metric, I have updated the Grafana dashboard and the alert rules in backend/docs/observability/

Additional Notes

All 224 unit and property tests in stream_contract pass with 0 warnings on cargo clippy --all-targets -- -D warnings and clean cargo fmt.