fix: Simplify Part message structure by flattening FilePart and DataPart by darrelmiller · Pull Request #1411 · a2aproject/A2A

darrelmiller · 2026-01-25T15:20:32Z

This change simplifies the Part message design by:

Renaming oneof 'part' to 'content' for clarity
Flattening FilePart fields (file_with_uri -> url, file_with_bytes -> bytes) directly into Part
Flattening DataPart by using google.protobuf.Value instead of Struct
Moving media_type and filename to Part level (available for all content types)
Removing separate FilePart and DataPart messages

Also updated migration guidance documentation to reference ancillary documents instead of requiring an in-spec appendix.

Related to issue #1255

Replaces PR #1363

This change simplifies the Part message design by: - Renaming oneof 'part' to 'content' for clarity - Flattening FilePart fields (file_with_uri -> url, file_with_bytes -> bytes) directly into Part - Flattening DataPart by using google.protobuf.Value instead of Struct - Moving media_type and filename to Part level (available for all content types) - Removing separate FilePart and DataPart messages Also updated migration guidance documentation to reference ancillary documents instead of requiring an in-spec appendix. Related to issue #1255

gemini-code-assist · 2026-01-25T15:20:48Z

Summary of Changes

Hello @darrelmiller, 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 significantly streamlines the Part message structure within the A2A protocol. It achieves this by directly embedding file and structured data content into the Part message itself, eliminating the need for separate FilePart and DataPart messages. This refactoring enhances the clarity and efficiency of the message design by consolidating related fields. Additionally, the documentation for migration guidance has been updated to reflect new guidelines.

Highlights

Message Structure Simplification: The 'Part' message design has been simplified by renaming its 'oneof' field from 'part' to 'content' for improved clarity.
FilePart Integration: Fields previously part of 'FilePart' (specifically 'file_with_uri' and 'file_with_bytes') have been flattened and integrated directly into the 'Part' message as 'url' and 'bytes' respectively.
DataPart Integration: The 'DataPart' structure has been flattened by directly using 'google.protobuf.Value' within the 'Part' message, replacing the need for a separate 'DataPart' message that used 'Struct'.
Unified Metadata Fields: Common metadata fields like 'media_type' and 'filename' have been moved to the top-level 'Part' message, making them available for all content types rather than being specific to file parts.
Removal of Redundant Messages: The separate 'FilePart' and 'DataPart' messages have been removed, reducing overall message complexity.
Documentation Update: Migration guidance documentation has been updated to refer to ancillary documents for major breaking changes, rather than requiring an in-spec appendix.

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Code Review

This pull request effectively simplifies the Part message structure by flattening FilePart and DataPart, which is a significant improvement for clarity and ease of use. The changes to the protobuf definition and the removal of the corresponding sections from the specification are well-executed.

However, the documentation in docs/specification.md is now inconsistent with the new protocol definition, which could confuse developers. Several examples and the migration guide in Appendix A still refer to the old, nested structure.

Key sections that need updating:

Section 6.7 (File Exchange) and Section 6.8 (Structured Data Exchange) examples are outdated.
Appendix A.2.1 (Breaking Change: Kind Discriminator Removed) is now incorrect as it describes a migration to a structure that this PR supersedes.

I've added one minor suggestion to clarify a comment in the .proto file. However, I strongly recommend updating the documentation as part of this PR to maintain its accuracy and usability.

specification/grpc/a2a.proto

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darrelmiller · 2026-01-25T15:37:04Z

/vote

git-vote · 2026-01-25T15:37:06Z

Vote created

@darrelmiller has called for a vote on fix: Simplify Part message structure by flattening FilePart and DataPart (#1411).

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@a2aproject/a2a-tsc

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The vote will be open for 11months 29days 3h 50m 24s. It will pass if at least 51% of the users with binding votes vote In favor 👍. Once it's closed, results will be published here as a new comment.

muscariello

LGTM

git-vote · 2026-01-26T15:55:41Z

Vote status

So far 25.00% of the users with binding vote are in favor and 0.00% are against (passing threshold: 51%).

Summary

In favor	Against	Abstain	Not voted
2	0	0	6

Binding votes (2)

User	Vote	Timestamp
darrelmiller	In favor	2026-01-25 15:38:10.0 +00:00:00
muscariello	In favor	2026-01-25 22:30:02.0 +00:00:00
@geneknit	Pending
@hughesthe1st	Pending
@ToddSegal	Pending
@000-000-000-000-000	Pending
@SivaNSAP	Pending
@spetschulatSFDC	Pending

git-vote · 2026-01-27T15:56:31Z

Vote status

So far 37.50% of the users with binding vote are in favor and 0.00% are against (passing threshold: 51%).

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In favor	Against	Abstain	Not voted
3	0	0	5

Binding votes (3)

User	Vote	Timestamp
darrelmiller	In favor	2026-01-25 15:38:10.0 +00:00:00
muscariello	In favor	2026-01-25 22:30:02.0 +00:00:00
spetschulatSFDC	In favor	2026-01-26 16:01:16.0 +00:00:00
@geneknit	Pending
@hughesthe1st	Pending
@ToddSegal	Pending
@000-000-000-000-000	Pending
@SivaNSAP	Pending

specification/grpc/a2a.proto

git-vote · 2026-01-28T09:26:02Z

Vote closed

The vote passed! 🎉

62.50% of the users with binding vote were in favor and 0.00% were against (passing threshold: 51%).

Summary

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5	0	0	3

Binding votes (5)

User	Vote	Timestamp
@ToddSegal	In favor	2026-01-27 17:16:11.0 +00:00:00
@darrelmiller	In favor	2026-01-25 15:38:10.0 +00:00:00
@hughesthe1st	In favor	2026-01-27 17:27:15.0 +00:00:00
@muscariello	In favor	2026-01-25 22:30:02.0 +00:00:00
@spetschulatSFDC	In favor	2026-01-26 16:01:16.0 +00:00:00

Non-binding votes (3)

User	Vote	Timestamp
@Tehsmash	In favor	2026-01-27 17:13:19.0 +00:00:00
@vinoo999	In favor	2026-01-27 17:17:13.0 +00:00:00
@EditUndo	In favor	2026-01-27 23:23:55.0 +00:00:00

🤖 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>

darrelmiller requested a review from a team as a code owner January 25, 2026 15:20

darrelmiller mentioned this pull request Jan 25, 2026

fix(spec): Refactor Part object to remove the need for FilePart and DataPart #1363

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Merge branch 'main' into feat/1255-clean

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muscariello linked an issue Jan 26, 2026 that may be closed by this pull request

[Feat]: Move media type from FilePart to base Part to support all part types #1255

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darrelmiller and others added 2 commits January 27, 2026 12:25

Update specification/grpc/a2a.proto

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muscariello merged commit bfae8f7 into main Jan 28, 2026
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muscariello deleted the feat/1255-clean branch January 28, 2026 16:48

a2a-bot mentioned this pull request Jan 27, 2026

chore(main): release 1.0.0 #1221

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ishymko mentioned this pull request Feb 12, 2026

[Bug]: Unexpected Deviation from A2A Specification a2aproject/a2a-js#330

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xui-will mentioned this pull request Mar 27, 2026

[Feat]: Incorporate a field of type Any in the gRPC spec #1300

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fix: Simplify Part message structure by flattening FilePart and DataPart#1411

fix: Simplify Part message structure by flattening FilePart and DataPart#1411
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darrelmiller commented Jan 25, 2026

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