The manual rests on one pinned release, one reference SDK, five more SDKs, one test kit, and one capture kit, and it names every place where those sources disagree.
How to read this manual ranks the sources and describes the kit. This page pins their versions, lists the conflicts between them, and records what the project changed after the tag.
The pin
| Item | Value |
|---|---|
| Release | A2A 1.0.1, tag v1.0.1 of github.com/a2aproject/A2A, commit 3303592588e388e62e0f69f701af531d2f4e3991, tagged 2026-05-28 |
| Protocol version | 1.0 in every request and card. Facts verified 2026-10-06. |
| Main branch | Commit 679ab3a of 2026-10-05, read for changes after the tag, and quoted only for rules the tag lacks |
| Reference SDK | a2a-sdk 1.2.2, tag v1.2.2 of github.com/a2aproject/a2a-python, commit 2f9e44af243df5c7c7a3da361c8d095324bcd5e3, Apache License 2.0 |
| Capture kit | the kit folder, standard library only, described in the kit README |
The changelog dates the release 2026-05-26, and the spec banner still names 1.0.0 as the latest release (conflict D16). The manual cites the reference SDK as sdk and a path under src/a2a/, and never quotes it.
Vendored files
The vendored files are copied from the tag under the Apache License 2.0 in LICENSE. The audit checks that every source marker uses a source key that the manual declares.
| File | Upstream | Source key |
|---|---|---|
| a2a.proto | specification/a2a.proto, 811 lines, normative |
proto and a message or enum name |
| specification.md | docs/specification.md, 3610 lines |
spec and a section number |
| specification-main.md | docs/specification.md on main at 679ab3a, 3618 lines, unreleased |
spec-main and a section number, only for rules added after the tag |
| docs.md | Fourteen project pages in 3019 lines, not normative. This edition adds multi-tenancy, custom-protocol-bindings, and extension-and-binding-governance. |
docs and a page name |
Section 1.4 of the spec gives the proto path as spec/a2a.proto, which is wrong (conflict D15). Two briefs index these files by line: the spec brief, with 40 findings and the register below, and the docs brief, which flags stale pages.
The SDKs and the test kit
Body sections compare six official SDKs and the official test kit, each read at one tag. The manual cites the reference SDK as sdk, and the others as sdk-go, sdk-java, sdk-js, sdk-dotnet, and sdk-rust, with a file path and the tag. It paraphrases them and never quotes them.
| Repository | Source key | Tag | Commit | Date |
|---|---|---|---|---|
| a2a-python | sdk |
v1.2.2 |
2f9e44a |
2026-10-05 |
| a2a-go | sdk-go |
v2.6.0 |
ebf17c5 |
2026-09-25 |
| a2a-java | sdk-java |
v1.4.0.Final |
6408194 |
2026-09-28 |
| a2a-js | sdk-js |
v1.3.0 |
29417a5 |
2026-09-29 |
| a2a-dotnet | sdk-dotnet |
v1.0.0-preview2 |
87fd448 |
2026-04-09 |
| a2a-rs | sdk-rust |
a2a-server-lf-v0.5.1 |
32c31f6 |
2026-09-30 |
| a2a-tck | a2a-tck and a file path |
1.0.0.alpha2 |
29063fe |
2026-05-27 |
The conflict register
This table condenses section 12.2 of the spec brief, and D36 to D40 were found while writing the manual. The last column says what the A2A repository did about each one after the tag, checked on 2026-10-06. Fixed on main means merged and unreleased. Partly fixed means that a residual remains on main.
| ID | The sources say | The manual follows | Discussed in | Upstream |
|---|---|---|---|---|
| D1 | Subscribe verb. Proto GET. §5.3 and §11.3.2 POST. |
The proto. Accept both. | front, 4.5, 5.2, R.1 | open PR #2068 |
| D2 | Blocking. §3.1.1 returns at once. §3.2.2 and the proto wait. | §3.2.2 and the proto | front, 4.1, 7.1 | open issue #2135 |
| D3 | Streams at interrupted states. §3.1.2 and §3.1.6 close at terminal states. §11.7 and the streaming guide also close at interrupted ones. §7.6.1 keeps auth streams open. | Close at terminal states, and expect either at interrupted ones | front, 1.2, 4.2, 4.5, R.3 | open PR #2270 |
| D4 | Push configuration name. Prose PushNotificationConfig. Proto TaskPushNotificationConfig. |
The proto name | 4.6, R.2 | partly fixed on main (PR #1981) |
| D5 | Create request. Prose and Appendix A CreateTaskPushNotificationConfigRequest. Proto TaskPushNotificationConfig. |
The proto | 4.6, R.1 | partly fixed on main (PR #1981) |
| D6 | Card security field. §3.1.11, §13.3, and the §8.5 sample security. Proto securityRequirements. |
The proto | front, 2.1, 2.3, 6.1, R.2 | partly fixed on main (PR #2046) |
| D7 | Extended card flag number. Appendix A.2.2 field 5. Proto field 4. | The proto | 2.3 | no activity |
| D8 | Protocol version. Appendix A.2.1 protocolVersions on the card. Proto protocolVersion per interface. |
One per interface | 2.1 | fixed on main, unreleased (PR #2165) |
| D9 | Stream event names. Migration guide taskStatusUpdate, taskArtifactUpdate. Proto statusUpdate, artifactUpdate. |
The proto | 4.5, 7.4 | fixed on main, unreleased (PR #2056) |
| D10 | Fields the proto lacks. Migration guide Task.createdAt, Task.lastModified, configId, TaskArtifactUpdateEvent.index. |
Do not send them | R.2, 7.4 | partly fixed on main (PR #2056) |
| D11 | Deprecated OAuth flows. Migration guide: implicit and password removed. Proto: kept, deprecated. | Present, never used | 6.1 | no activity |
| D12 | Pagination names. Migration guide cursor, limit, nextCursor. Proto pageToken, pageSize, nextPageToken. |
The proto | 4.3 | fixed on main, unreleased (PR #2165) |
| D13 | Error body. §6.4 and §6.5 samples application/problem+json. Migration guide application/json. §11.6 google.rpc.Status. |
§11.6 | 5.5 | open PR #1641 and PR #1689 |
| D14 | JSON-RPC method template. §9.3 category/action. §9.1 and §9.4 PascalCase. |
PascalCase | 5.1 | no activity |
| D15 | Proto path. §1.4 spec/a2a.proto. §5.7, §10.1, and the repository specification/a2a.proto. |
The repository | 1.1, Vendored files | no activity |
| D16 | Release and date. Banner: 1.0.0 is latest. Changelog 2026-05-26. Tag message 2026-04-23. Tag commit 2026-05-28. | 1.0.1, tagged 2026-05-28 | The pin | open PR #2072 |
| D17 | Header registrations. §14.2.1 and §14.2.2 cite Section 3.2.5. Service parameters are §3.2.6. | §3.2.6 | 5.4 | open issue #2305 |
| D18 | TLS version. Spec 1.3 or later. Enterprise guide 1.2 or later. | The spec | 6.1 | no activity |
| D19 | Empty required arrays. §5.7 wants one element at least. The §8.4.1 example has empty skills, and empty tasks is legitimate. |
Empty tasks for no results, a skill on every real card |
2.1, R.2 | open issue #2122 |
| D20 | The typ header. §8.4.2 lists typ among the MUST fields and words it as SHOULD. |
Send alg, kid, and typ set to JOSE |
2.3 | no activity |
| D21 | Signing steps. §8.4.2 and §8.4.3 remove default values. §8.4.1 keeps REQUIRED and set optional fields. | §8.4.1 | 2.3 | open issue #2249 |
| D22 | JSON naming example. §5.5 push_notification_config. Proto task_push_notification_config. |
The proto | R.2 | no activity |
| D23 | Samples that break REQUIRED. Some omit messageId, artifactId, or an event's contextId. |
Never copy a sample as it is | 3.1, 6.2 | partly fixed on main (PR #2083) |
| D24 | Invalid JSON. The samples in §4.6.1, §6.7, and §9.4.1. | Never copy a sample as it is | 3.2, 6.2 | open PR #1657 |
| D25 | Layer 2 diagram. §1.3 shows Get Agent Card. §3.1 defines only Get Extended Agent Card. | The diagram is informal | 1.1 | no activity |
| D26 | Mandatory operations. §3.1 requires them all. §3.3.4 lets flags decline streaming, push, and the extended card. | The capability flags | 2.2 | no activity |
| D27 | Transport in a guide. Core Concepts: JSON-RPC 2.0 for everything. Spec: three bindings. | The spec | 5.1 | no activity |
| D28 | Who creates the context id. Core Concepts: the server. Spec: a client can propose one. | The spec | 3.5 | open issue #1317 |
| D29 | States from extensions. The extensions guide lists extensions that add states, and forbids new enum values. | Neither is normative. Add no states. | 3.4, 6.2 | no activity |
| D30 | Extension activation. §4.6.1 JSON-RPC parameters. §9.2 HTTP headers. | The header | 5.4 | no activity |
| D31 | Version as a parameter. §3.6.1 allows a request parameter. §9.2 and §11.2 require headers. | The header | 5.4 | open issue #2184 |
| D32 | Old endpoint names. The what-is-a2a diagram: POST /sendMessage, /.well-known/agent-card. |
message:send, agent-card.json |
2.2 | fixed on main, unreleased (PR #2261) |
| D33 | Stream type in a guide. Streaming guide SendStreamingMessageResponse. Spec StreamResponse. |
The spec | 4.5 | no activity |
| D34 | gRPC interface URL. Proto: an absolute HTTPS URL. gRPC dials a host and a port. | No rule at the tag | 2.1, 5.3 | fixed on main, unreleased (PR #1997) |
| D35 | Role spelling. §2.2 user and agent. Proto and §5.5 ROLE_USER, ROLE_AGENT. |
The enum names | 3.1 | no activity |
| D36 | Another client's task. §3.3.2 calls it an authorization error and forbids revealing that it exists. | TaskNotFoundError |
6.1 | no activity |
| D37 | A 0.3 state name. §3.4.3 input-required. Proto TASK_STATE_INPUT_REQUIRED. |
The proto name | 3.4 | open PR #2155 |
| D38 | Cancel transitions. Migration guide: clarified in 1.0. Spec: no transition table. | Transitions are implementation behavior | 3.4 | open issue #1992 |
| D39 | Version in samples. §9.2, §11.2, and §14.2.1 send A2A-Version: 0.3. |
Send 1.0 |
5.4 | no activity |
| D40 | Old extended card flag. Appendix A.2.2 supportsExtendedAgentCard. Migration guide and SDK supportsAuthenticatedExtendedCard. |
extendedAgentCard in capabilities |
2.3, 7.4 | no activity |
Discrepancies found after the register
Research for this edition found twenty more places where a docs page, an appendix, or a sample disagrees with the proto or the spec. None changes what the manual follows. The last column says whether main still has the text, as checked on 2026-10-06.
| ID | The sources say | The manual follows | Discussed in | On main |
|---|---|---|---|---|
| N1 | Stream event kind in the guide. Migration guide, for 0.3: kind values taskStatusUpdate and taskArtifactUpdate. Appendix A.2.1 and the 0.3 schema: status-update and artifact-update. |
Appendix A.2.1 | R.6 only | fixed |
| N2 | Extensions path. Migration guide agentCard.extensions. Proto capabilities.extensions. |
The proto | 6.2, R.2 | unchanged |
| N3 | Tenant scope. Migration guide: tenant scoping in gRPC requests. Proto: tenant on every request message, and a /{tenant} route for every rpc. |
The proto | 5.2 | unchanged |
| N4 | ListTasks in 0.3. Migration guide: not available in 0.3. The 0.3 prose lists tasks/list, and the 0.3 proto and schema do not. |
The guide, read as not in the 0.3 schema | R.6 only | no change needed |
| N5 | Upgrade headings. Appendix A.2.1 says pre-0.3.x under the heading about the 1.0 change. |
Read as pre-1.0 | R.6 only | unchanged |
| N6 | Removal timeline. Appendix A sets removal at 0.5.0 or later for names that 1.0 renamed, and calls the timeline an example. | §1.4: the next major release | R.6 only | unchanged |
| N7 | Removed card field name. Appendix A.2.2 supports_extended_agent_card, field 13. The 0.3 proto supports_authenticated_extended_card, field 13. |
The 0.3 proto | R.6 only | unchanged |
| N8 | Version in the §10.2 sample. The gRPC sample sends a2a-version 0.3, which D39 does not list. |
Send 1.0 |
5.3 | unchanged |
| N9 | Config id name. Migration guide config_id. Proto id. |
The proto | R.2 | fixed |
| N10 | Extension lists as new fields. Migration guide adds Message.extensions and Artifact.extensions in 1.0. Both exist in the 0.3 proto. |
Not new | R.6 only | unchanged |
| N11 | Mutual TLS as new. Migration guide adds mutual TLS in 1.0. The 0.3 proto has mtls_security_scheme. |
Not new | R.6 only | unchanged |
| N12 | Tenant routes. §5.3, §11.3, and §11.5 list no /{tenant} route. The proto adds one to every rpc. |
The proto | 5.2, R.1 | unchanged |
| N13 | Tenant field number. ListTaskPushNotificationConfigsRequest.tenant is field 4. Every other request has field 1. |
No conflict. Visible in gRPC only. | R.6 only | unchanged |
| N14 | filename on any part. Migration guide: filename on every part. Proto comment: for the file. |
The proto allows it on any part. Use it for files. | 3.2 | unchanged |
| N15 | Create request in Appendix A. The table names CreateTaskPushNotificationConfigRequest as current. It is the 0.3 type. |
The proto, as D5 | 4.6 | unchanged |
| N16 | Operation aliases. Migration guide: aliases during the transition. The proto and the method set define none. SDK compatibility layers do. | The spec. Name the SDK layer. | R.6 only | unchanged |
| N17 | The flipped default. Migration guide shows returnImmediately as new. 0.3 blocking defaulted to false, no wait. 1.0 returnImmediately defaults to false, a wait. |
§3.2.2 and the proto | 4.1 | unchanged |
| N18 | Card sample in the extensions guide. A top-level url, the 0.3 shape. |
supportedInterfaces |
R.6 only | fixed |
| N19 | A gRPC-specific wrapper. §10.5.1 calls TaskPushNotificationConfig a gRPC resource type. The proto uses it in every binding. |
The proto | R.6 only | unchanged |
| N20 | Security in the tenancy guide. The multi-tenancy page securitySchemes and security. Proto securityRequirements. |
The proto, as D6 | R.6 only | unchanged |
After v1.0.1
The manual checked main of the A2A repository at commit 679ab3a, dated 2026-10-05, and found 73 commits after the tag. One changes the proto: PR #1997 lets a gRPC interface url be a hostname:port address, which settles D34. It is the only entry in the pending 1.0.2 release, PR #2072, still open.
PR #2081 added §7.6.4, In-Task Authorization Scope, which the manual quotes with the key spec-main. Branch dev-1.1, at commit db39eb5 of 2026-09-22, holds the 1.1 work: a generation field and a task timeline. The approved fixes for D1 and D3 target that branch and are still open. No tag newer than v1.0.1 existed on 2026-10-06.
Sources: manual.json pin, sources and quoteSources; research/sources/README.md and LICENSE; spec §1.4, §3.6, §5.7, §10.1 (research/sources/specification.md); research/sources/specification-main.md §7.6.4 (main at 679ab3a); research/brief-spec.md sections 1.1, 12.2 and 14; research/brief-docs.md; research/conflicts-upstream.md, research/migration.md section D.6, research/sdk-splits.md section 1, research/conformance-tools.md (research of 2026-10-06); a2aproject/A2A main at 679ab3a, branch dev-1.1 at db39eb5, and the PRs and issues in the Upstream column, checked 2026-10-06; the a2a-python checkout at tag v1.2.2 (pyproject.toml, LICENSE); the SDK and a2a-tck repositories at the tags in the SDK table; manuals/a2a-101/capture/README.md, capture/run.py