Bilyana Gospodinova engineered core backend infrastructure for the hiero-ledger/hiero-mirror-node repository, focusing on modular state management, contract execution, and robust API development. She implemented scalable state-sharing mechanisms and modularized service layers using Java and Kotlin, enabling safer cross-service interactions and efficient contract data handling. Her work included optimizing REST API endpoints, refining database querying, and integrating CI/CD pipelines for automated testing. By addressing concurrency, caching, and error handling, Bilyana improved system reliability and observability. Her technical depth is evident in the seamless upgrades, targeted bug fixes, and thoughtful refactoring that collectively enhanced maintainability and accelerated feature delivery across the project.
Concise monthly summary for 2025-10 focusing on business value and technical achievements for hiero-ledger/hiero-mirror-node.
Concise monthly summary for 2025-10 focusing on business value and technical achievements for hiero-ledger/hiero-mirror-node.
Month: 2025-09 | Repository: hiero-ledger/hiero-mirror-node Key features delivered - Contract Management REST API: endpoints to list contracts, retrieve contract state, and fetch contract results by timestamp; added testing coverage. - Hedera app upgrade and contract processing refactor: Hedera App 0.65.1 upgrade; extends account management with hooks and lambda storage fields; refactored contract processing for efficiency and validation. - Web3 initialization overhaul: removes legacy warmup; asynchronously initializes transaction executors per EVM version to reduce startup errors. Major bugs fixed - Hollow account input handling: ensure hollow sender accounts have a default key; allows transactions to proceed and prevents unhandled input failures for inner child transactions. - Reduce log noise for REVERTED_SUCCESS: omit logging of REVERTED_SUCCESS child errors; added tests to verify contract calls with child errors do not raise unnecessary logs or exceptions. Overall impact and accomplishments - Strengthened reliability and developer productivity through improved API capabilities, faster startup, and clearer observability. Expanded test coverage and validation for contract processing, leading to more robust operations and safer deployments. Technologies/skills demonstrated - REST API design and testing; Hedera App upgrade and hooks; asynchronous startup optimization; precise bug fixing with targeted tests; improvements to logging and observability.
Month: 2025-09 | Repository: hiero-ledger/hiero-mirror-node Key features delivered - Contract Management REST API: endpoints to list contracts, retrieve contract state, and fetch contract results by timestamp; added testing coverage. - Hedera app upgrade and contract processing refactor: Hedera App 0.65.1 upgrade; extends account management with hooks and lambda storage fields; refactored contract processing for efficiency and validation. - Web3 initialization overhaul: removes legacy warmup; asynchronously initializes transaction executors per EVM version to reduce startup errors. Major bugs fixed - Hollow account input handling: ensure hollow sender accounts have a default key; allows transactions to proceed and prevents unhandled input failures for inner child transactions. - Reduce log noise for REVERTED_SUCCESS: omit logging of REVERTED_SUCCESS child errors; added tests to verify contract calls with child errors do not raise unnecessary logs or exceptions. Overall impact and accomplishments - Strengthened reliability and developer productivity through improved API capabilities, faster startup, and clearer observability. Expanded test coverage and validation for contract processing, leading to more robust operations and safer deployments. Technologies/skills demonstrated - REST API design and testing; Hedera App upgrade and hooks; asynchronous startup optimization; precise bug fixing with targeted tests; improvements to logging and observability.
August 2025 focused on stabilizing Ethereum-compatible contract data indexing and improving accuracy of contract transaction details in hiero-ledger/hiero-mirror-node. Delivered two high-impact bug fixes and a migration-enhancement to ensure block-level indexing semantics and data persistence across imports, strengthening data reliability for analytics and user UX.
August 2025 focused on stabilizing Ethereum-compatible contract data indexing and improving accuracy of contract transaction details in hiero-ledger/hiero-mirror-node. Delivered two high-impact bug fixes and a migration-enhancement to ensure block-level indexing semantics and data persistence across imports, strengthening data reliability for analytics and user UX.
June 2025 (2025-06) focused on stabilizing core Web3 state management, ensuring accurate consensus timing, and improving observability for the Mirror Node. Delivered three key bug fixes that restore functionality, correct timing semantics, and streamline logging and payload handling, with tests updated to validate behavior.
June 2025 (2025-06) focused on stabilizing core Web3 state management, ensuring accurate consensus timing, and improving observability for the Mirror Node. Delivered three key bug fixes that restore functionality, correct timing semantics, and streamline logging and payload handling, with tests updated to validate behavior.
May 2025: Delivered a critical security/validation enhancement in hiero-mirror-node by prohibiting smart contract accounts from sending transactions. The change introduces a dedicated read state AbstractAliasedAccountReadableKVState to map entities to accounts efficiently, and standardizes error handling by returning PAYER_ACCOUNT_NOT_FOUND when a contract account is detected as a sender. The update aligns with existing error semantics across the system, improving transaction validity checks, security posture, and overall reliability of the payer resolution path.
May 2025: Delivered a critical security/validation enhancement in hiero-mirror-node by prohibiting smart contract accounts from sending transactions. The change introduces a dedicated read state AbstractAliasedAccountReadableKVState to map entities to accounts efficiently, and standardizes error handling by returning PAYER_ACCOUNT_NOT_FOUND when a contract account is detected as a sender. The update aligns with existing error semantics across the system, improving transaction validity checks, security posture, and overall reliability of the payer resolution path.
April 2025 (2025-04) monthly summary for the hiero-mirror-node project. Focused on delivering upgrade-driven features, hardening key pathways, and aligning with Hedera release changes to reduce runtime risk and improve maintainability. The work enhances stability, reproducibility, and readiness for future Hedera app migrations.
April 2025 (2025-04) monthly summary for the hiero-mirror-node project. Focused on delivering upgrade-driven features, hardening key pathways, and aligning with Hedera release changes to reduce runtime risk and improve maintainability. The work enhances stability, reproducibility, and readiness for future Hedera app migrations.
March 2025 monthly summary for hiero-mirror-node. Focused on stabilizing throttle behavior under concurrency, expanding test coverage for NFT minting flows, and enabling environment-driven Web3 testing. Key outcomes include remediation of race conditions by temporarily disabling deterministic throttle and introducing a custom rate-limiting throttle; development/testing tooling to bypass throttling for QA; expanded integration tests for modularizedServices NFT minting and related scenarios; new EntityCountsSingleton to satisfy Web3 dependencies; and a refactor of k6 Web3 tests to support environment variables with updated documentation.
March 2025 monthly summary for hiero-mirror-node. Focused on stabilizing throttle behavior under concurrency, expanding test coverage for NFT minting flows, and enabling environment-driven Web3 testing. Key outcomes include remediation of race conditions by temporarily disabling deterministic throttle and introducing a custom rate-limiting throttle; development/testing tooling to bypass throttling for QA; expanded integration tests for modularizedServices NFT minting and related scenarios; new EntityCountsSingleton to satisfy Web3 dependencies; and a refactor of k6 Web3 tests to support environment variables with updated documentation.
February 2025 monthly summary for hiero-ledger/hiero-mirror-node: Focused on stabilizing modularized services and improving test reliability, while introducing transaction-scoped caching to improve correctness in contract call paths. Delivered key features with aligned test suites across historical, EVM, dynamic calls, and acceptance tests, and eliminated cross-transaction data leakage by replacing shared caches with per-transaction caches.
February 2025 monthly summary for hiero-ledger/hiero-mirror-node: Focused on stabilizing modularized services and improving test reliability, while introducing transaction-scoped caching to improve correctness in contract call paths. Delivered key features with aligned test suites across historical, EVM, dynamic calls, and acceptance tests, and eliminated cross-transaction data leakage by replacing shared caches with per-transaction caches.
January 2025: Key deployment and test improvements for hiero-mirror-node. Consolidated test reliability across mono and modular configurations, and enhanced contract deployment efficiency by removing file upload and using maxSignedTxnSize to support larger bytecode in a single transaction.
January 2025: Key deployment and test improvements for hiero-mirror-node. Consolidated test reliability across mono and modular configurations, and enhanced contract deployment efficiency by removing file upload and using maxSignedTxnSize to support larger bytecode in a single transaction.
Month: 2024-12 — Focused on strengthening modular architecture and reliability for hiero-mirror-node. Delivered targeted improvements: a modularized services infrastructure enabling phased integration of reusable services; resolution of read-only mode issues for contract bytecode population; and an enhanced gas throttling mechanism to support higher throughput. These changes improve modularity, state initialization, and contract data handling, accelerating future service delivery while improving performance and reliability.
Month: 2024-12 — Focused on strengthening modular architecture and reliability for hiero-mirror-node. Delivered targeted improvements: a modularized services infrastructure enabling phased integration of reusable services; resolution of read-only mode issues for contract bytecode population; and an enhanced gas throttling mechanism to support higher throughput. These changes improve modularity, state initialization, and contract data handling, accelerating future service delivery while improving performance and reliability.
November 2024: Delivered foundational state management infrastructure for the mirror node, enabling safer cross-service state sharing and laying a scalable basis for future improvements to token, contract, and file operations.
November 2024: Delivered foundational state management infrastructure for the mirror node, enabling safer cross-service state sharing and laying a scalable basis for future improvements to token, contract, and file operations.
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