fix: Add missing metadata field to Part message in gRPC specification#1019
fix: Add missing metadata field to Part message in gRPC specification#1019holtskinner merged 2 commits intoa2aproject:mainfrom
Conversation
The Part message in the gRPC proto was missing the metadata field that exists in the TypeScript/JSON specification. This caused data loss when converting between Python and gRPC representations, particularly affecting ADK functionality that embeds part types in metadata. Fixes a2aproject#1005
There was a problem hiding this comment.
Summary of Changes
Hello @ipapapa, I'm Gemini Code Assist1! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!
This pull request addresses a critical issue where important metadata was being lost during data conversions between Python and gRPC due to a missing field in the gRPC specification's Part message. By adding the metadata field, the change ensures data consistency across different language specifications and prevents data integrity problems, particularly for information like ADK function call/response types.
Highlights
- gRPC Specification Update: Adds the previously missing "metadata" field to the "Part" message within the gRPC specification.
- Cross-Language Consistency: Resolves an inconsistency between TypeScript/JSON and gRPC protocol definitions, ensuring uniform data structures.
- Data Integrity: Prevents potential data loss during conversions between Python and gRPC representations by ensuring all relevant metadata is preserved.
Using Gemini Code Assist
The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.
Invoking Gemini
You can request assistance from Gemini at any point in your pull request via creating an issue comment (i.e. comment on the pull request page) using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands.
| Feature | Command | Description |
|---|---|---|
| Code Review | /gemini review |
Performs a code review for the current pull request in its current state. |
| Pull Request Summary | /gemini summary |
Provides a summary of the current pull request in its current state. |
| Comment | @gemini-code-assist | Responds in comments when explicitly tagged, both in issue comments and review comments. |
| Help | /gemini help |
Displays a list of available commands. |
Customization
To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.
Limitations & Feedback
Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.
You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.
Footnotes
-
Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩
There was a problem hiding this comment.
Code Review
This pull request correctly addresses an inconsistency in the gRPC specification by adding the metadata field to the Part message. The change is well-justified, as it prevents data loss during conversions and aligns the gRPC protocol definition with the existing TypeScript, JSON, and documentation specifications. The implementation is clean, uses the correct field type and tag, and follows the conventions of the existing protobuf file. This is a solid fix.
🤖 I have created a release *beep* *boop* --- ## [1.0.0](v0.3.0...v1.0.0) (2026-03-12) ### ⚠ BREAKING CHANGES * **spec:** Combine `TaskPushNotificationConfig` and `PushNotificationConfig` ([#1500](#1500)) * **spec:** remove duplicated ID from the create task push config request ([#1487](#1487)) * **spec:** pluralize configs in `ListTaskPushNotificationConfigs` ([#1486](#1486)) * **spec:** Add LF prefix to the package. ([#1474](#1474)) * **spec:** Switch to non-complex IDs in requests ([#1389](#1389)) * **spec:** Standardize spelling of "canceled" to use American Spelling throughout ([#1283](#1283)) * **spec:** Align enum format with ADR-001 ProtoJSON specification ([#1384](#1384)) * **spec:** Remove redundant `final` field from `TaskStatusUpdateEvent` ([#1308](#1308)) * **spec:** Move `extendedAgentCard` field to `AgentCapabilities` ([#1307](#1307)) * **spec:** Fixes for the last_updated_after field ([#1358](#1358)) * **spec:** modernize oauth 2.0 flows - remove implicit/password, add device code / pkce ([#1303](#1303)) * **spec:** Make "message" field name consistent between protocol bindings ([#1302](#1302)) * **spec:** Remove deprecated fields from a2a.proto for v1.0 release ([#1301](#1301)) * **spec:** Rename `supportsAuthenticatedExtendedCard` to `supportsExtendedAgentCard` ([#1222](#1222)) * **spec:** Remove v1s from a2a url http bindings * **spec:** Large refactor of specification to separate application protocol definition from mapping to transports ### Features * **spec:** Add `tasks/list` method with filtering and pagination to the specification ([0a9f629](0a9f629)) * **spec:** modernize oauth 2.0 flows - remove implicit/password, add device code / pkce ([#1303](#1303)) ([525ff38](525ff38)) * **spec:** Natively Support Multi-tenancy on gRPC through an additional scope field on the request. ([#1195](#1195)) ([cfbce32](cfbce32)), closes [#1148](#1148) * **spec:** Provide ability for SDKs to be backwards compatible. ([#1401](#1401)) ([227e249](227e249)) * **spec:** Remove v1s from a2a url http bindings ([1bd263f](1bd263f)) ### Bug Fixes * Add missing metadata field to Part message in gRPC specification ([#1019](#1019)) ([b3b266d](b3b266d)), closes [#1005](#1005) * Add name field to FilePart protobuf message ([#983](#983)) ([2b7cb6f](2b7cb6f)), closes [#984](#984) * Clarify blocking calls return on interrupted states ([#1403](#1403)) ([0655ff3](0655ff3)) * **doc:** Makes JSON-RPC SendMessage response clearer ([#1241](#1241)) ([5792804](5792804)) * **docs:** Clearer wording around context id. ([#1588](#1588)) ([dec790a](dec790a)) * **grpc:** Fix inconsistent property name between gRPC and JSON-RPC in Message object ([#1100](#1100)) ([2a1f819](2a1f819)) * **grpc:** missing field in gRPC spec - state_transition_history ([#1138](#1138)) ([a2de798](a2de798)), closes [#1139](#1139) * **grpc:** Update `CreateTaskPushNotificationConfig` endpoint to `/v1/{parent=tasks/*/pushNotificationConfigs}` ([#979](#979)) ([911f9b0](911f9b0)) * **proto:** Add icon_url to a2a.proto ([#986](#986)) ([17e7f62](17e7f62)) * **proto:** Adds metadata field to A2A DataPart proto ([#1004](#1004)) ([a8b45dc](a8b45dc)) * Remove unimplemented state_transition_history capability field ([#1396](#1396)) ([c768a44](c768a44)), closes [#1228](#1228) * Restore CreateTaskPushNotificationConfig method naming ([#1402](#1402)) ([d14f410](d14f410)) * Revert "chore(gRPC): Update a2a.proto to include metadata on GetTaskRequest" ([#1000](#1000)) ([e6b8c65](e6b8c65)) * Simplify Part message structure by flattening FilePart and DataPart ([#1411](#1411)) ([bfae8f7](bfae8f7)) * **spec:** Add LF prefix to the package. ([#1474](#1474)) ([a54e809](a54e809)) * **spec:** add metadata to `CancelTaskRequest` ([#1485](#1485)) ([c441b91](c441b91)), closes [#1484](#1484) * **spec:** Added clarification on timestamps in HTTP query params ([#1425](#1425)) ([6292104](6292104)) * **spec:** Added clarifying text around messages and artifacts ([#1424](#1424)) ([b03d141](b03d141)) * **spec:** Adjust field number for `ListTasksRequest.tenant` to prevent missing number ([#1470](#1470)) ([cd16c52](cd16c52)) * **spec:** Clarify contextId behavior when message is sent with taskId but without contextId ([#1309](#1309)) ([a336a5a](a336a5a)) * **spec:** Clarify versioning strategy and client responsibilities in protocol specification ([#1259](#1259)) ([a4afeea](a4afeea)) * **spec:** Fix/1251 clarify authentication scheme ([#1256](#1256)) ([3e6c7db](3e6c7db)) * **spec:** Fixes for the last_updated_after field ([#1358](#1358)) ([0e204bf](0e204bf)) * **spec:** Make "message" field name consistent between protocol bindings ([#1302](#1302)) ([1e5f462](1e5f462)), closes [#1230](#1230) * **spec:** make `history_length` optional ([#1071](#1071)) ([0572953](0572953)) * **spec:** pluralize configs in `ListTaskPushNotificationConfigs` ([#1486](#1486)) ([cf735cb](cf735cb)) * **spec:** Remove config from binding. ([#1587](#1587)) ([010b9cc](010b9cc)) * **spec:** Remove deprecated fields from a2a.proto for v1.0 release ([#1301](#1301)) ([60f83c3](60f83c3)), closes [#1227](#1227) * **spec:** remove duplicated ID from the create task push config request ([#1487](#1487)) ([393898d](393898d)) * **spec:** Remove metadata field from ListTasksRequest ([#1235](#1235)) ([b6ef9ee](b6ef9ee)) * **spec:** Remove reserved and fix tags ordering ([#1494](#1494)) ([1997c9d](1997c9d)) * **spec:** Rename `supportsAuthenticatedExtendedCard` to `supportsExtendedAgentCard` ([#1222](#1222)) ([c196824](c196824)), closes [#1215](#1215) * **spec:** Standardize spelling of "canceled" to use American Spelling throughout ([#1283](#1283)) ([4dd980f](4dd980f)) * **spec:** Suggest Unique Identifier fields to be UUID ([#966](#966)) ([00cf76e](00cf76e)) * **spec:** Switch to non-complex IDs in requests ([#1389](#1389)) ([2596c1c](2596c1c)), closes [#1390](#1390) * **spec:** Update security schemes example ([#1364](#1364)) ([f9a8f5b](f9a8f5b)) * Update the Java tutorials and descriptions ([#1181](#1181)) ([202aa06](202aa06)) ### Documentation * **spec:** Align enum format with ADR-001 ProtoJSON specification ([#1384](#1384)) ([810eaa1](810eaa1)), closes [#1344](#1344) ### Code Refactoring * **spec:** Combine `TaskPushNotificationConfig` and `PushNotificationConfig` ([#1500](#1500)) ([d1ed0da](d1ed0da)) * **spec:** Large refactor of specification to separate application protocol definition from mapping to transports ([b078419](b078419)) * **spec:** Move `extendedAgentCard` field to `AgentCapabilities` ([#1307](#1307)) ([40d6286](40d6286)) * **spec:** Remove redundant `final` field from `TaskStatusUpdateEvent` ([#1308](#1308)) ([5b101cc](5b101cc)) --- This PR was generated with [Release Please](https://github.com/googleapis/release-please). See [documentation](https://github.com/googleapis/release-please#release-please). Co-authored-by: Amye Scavarda Perrin <amye@amye.org> Co-authored-by: Holt Skinner <13262395+holtskinner@users.noreply.github.com>
Summary
metadatafield to thePartmessage in the gRPC specificationProblem
The
Partmessage inspecification/grpc/a2a.protowas missing themetadatafield that exists in the TypeScript and Python specifications. This caused important metadata (like ADK function call/response types) to be lost during conversions between Python and gRPC representations.Solution
Added
google.protobuf.Struct metadata = 4;to thePartmessage, following the same pattern used by other proto messages in the specification (Task, Message, Artifact, etc.).Fixes #1005