docs: Added adr template and protojson adr

[darrelmiller]

Added ADR that captures decision to use ProtoJSON as the normative reference for JSON serialization

[gemini-code-assist]

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 introduces an ADR template and a specific ADR (ADR-001) that documents the decision to use ProtoJSON for JSON serialization in the A2A specification. This aims to standardize JSON serialization and improve interoperability, but it also acknowledges potential breaking changes and migration efforts for existing implementations.

Highlights

• ADR Template: Adds a template for Architecture Decision Records (ADRs) to standardize the decision-making process.
• ProtoJSON ADR: Introduces ADR-001, which captures the decision to use ProtoJSON as the normative reference for JSON serialization within the A2A specification.
• Breaking Changes: Highlights potential breaking changes due to the adoption of ProtoJSON, specifically regarding enum casing (SCREAMING_SNAKE_CASE) and the loss of roundtrip capability for unknown values.

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[gemini-code-assist]

Code Review

This pull request introduces an Architecture Decision Record (ADR) for using ProtoJSON as the standard for JSON serialization, along with a template for future ADRs. The changes are well-structured and clearly articulate the decision-making process. My feedback includes a few minor corrections for typos and grammar in the ADR, and a suggestion to improve consistency between the new ADR and the template.

[darrelmiller]

/vote

[git-vote]

Vote created

@darrelmiller has called for a vote on Added adr template and protojson adr (#1214).

The members of the following teams have binding votes:

Team
@a2aproject/a2a-tsc

Non-binding votes are also appreciated as a sign of support!

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[git-vote]

Vote status

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

Summary

In favor	Against	Abstain	Not voted
3	0	0	5

Binding votes (3)

User	Vote	Timestamp
ToddSegal	In favor	2025-11-25 17:57:04.0 +00:00:00
darrelmiller	In favor	2025-11-26 12:27:04.0 +00:00:00
muscariello	In favor	2025-11-26 16:56:57.0 +00:00:00
@lerhaupt	Pending
@geneknit	Pending
@hughesthe1st	Pending
@000-000-000-000-000	Pending
@SivaNSAP	Pending

[git-vote]

Vote status

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

Summary

In favor	Against	Abstain	Not voted
3	0	0	5

Binding votes (3)

User	Vote	Timestamp
ToddSegal	In favor	2025-11-25 17:57:04.0 +00:00:00
darrelmiller	In favor	2025-11-26 12:27:04.0 +00:00:00
muscariello	In favor	2025-11-26 16:56:57.0 +00:00:00
@lerhaupt	Pending
@geneknit	Pending
@hughesthe1st	Pending
@000-000-000-000-000	Pending
@SivaNSAP	Pending

[git-vote]

Vote status

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

Summary

In favor	Against	Abstain	Not voted
3	0	0	5

Binding votes (3)

User	Vote	Timestamp
ToddSegal	In favor	2025-11-25 17:57:04.0 +00:00:00
darrelmiller	In favor	2025-11-26 12:27:04.0 +00:00:00
muscariello	In favor	2025-11-26 16:56:57.0 +00:00:00
@lerhaupt	Pending
@geneknit	Pending
@hughesthe1st	Pending
@000-000-000-000-000	Pending
@SivaNSAP	Pending

[git-vote]

Vote status

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

Summary

In favor	Against	Abstain	Not voted
3	0	0	5

Binding votes (3)

User	Vote	Timestamp
ToddSegal	In favor	2025-11-25 17:57:04.0 +00:00:00
darrelmiller	In favor	2025-11-26 12:27:04.0 +00:00:00
muscariello	In favor	2025-11-26 16:56:57.0 +00:00:00
@lerhaupt	Pending
@geneknit	Pending
@hughesthe1st	Pending
@000-000-000-000-000	Pending
@SivaNSAP	Pending

[git-vote]

Vote status

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

Summary

In favor	Against	Abstain	Not voted
3	0	0	5

Binding votes (3)

User	Vote	Timestamp
ToddSegal	In favor	2025-11-25 17:57:04.0 +00:00:00
darrelmiller	In favor	2025-11-26 12:27:04.0 +00:00:00
muscariello	In favor	2025-11-26 16:56:57.0 +00:00:00
@lerhaupt	Pending
@geneknit	Pending
@hughesthe1st	Pending
@000-000-000-000-000	Pending
@SivaNSAP	Pending

[git-vote]

Vote status

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

Summary

In favor	Against	Abstain	Not voted
3	0	0	5

Binding votes (3)

User	Vote	Timestamp
ToddSegal	In favor	2025-11-25 17:57:04.0 +00:00:00
darrelmiller	In favor	2025-11-26 12:27:04.0 +00:00:00
muscariello	In favor	2025-11-26 16:56:57.0 +00:00:00
@lerhaupt	Pending
@geneknit	Pending
@hughesthe1st	Pending
@000-000-000-000-000	Pending
@SivaNSAP	Pending

[git-vote]

Vote closed

The vote did not pass.

50.00% of the users with binding vote were in favor and 0.00% were against (passing threshold: 51%).

Summary

In favor	Against	Abstain	Not voted
4	0	0	4

Binding votes (4)

User	Vote	Timestamp
@000-000-000-000-000	In favor	2025-12-02 0:36:28.0 +00:00:00
@ToddSegal	In favor	2025-11-25 17:57:04.0 +00:00:00
@darrelmiller	In favor	2025-11-26 12:27:04.0 +00:00:00
@muscariello	In favor	2025-11-26 16:56:57.0 +00:00:00

[amye]

This vote actually passed, editing labels to be clear.