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fix: Clarify blocking calls return on interrupted states#1403

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muscariello merged 4 commits intoa2aproject:mainfrom
madankumarpichamuthu:fix/1264-blocking-calls-interrupted-states
Jan 29, 2026
Merged

fix: Clarify blocking calls return on interrupted states#1403
muscariello merged 4 commits intoa2aproject:mainfrom
madankumarpichamuthu:fix/1264-blocking-calls-interrupted-states

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Updates the specification to clarify that blocking SendMessage calls must return when tasks reach interrupted states (input_required, auth_required) in addition to terminal states. This prevents deadlock scenarios where tasks waiting for user input would cause blocking calls to hang indefinitely.

Changes:

  • specification/grpc/a2a.proto: Updated blocking field comment to include "terminal or interrupted state"
  • specification/grpc/a2a.proto: Fixed AUTH_REQUIRED classification to be an "interrupted state" (consistent with INPUT_REQUIRED)
  • docs/specification.md: Updated blocking behavior description to include interrupted states and changed "final task state" to "current task state"

This enables proper client workflows where blocking calls can return on INPUT_REQUIRED or AUTH_REQUIRED, allowing clients to provide the needed information and resume with subsequent SendMessage calls.

Fixes #1264

Updates the specification to clarify that blocking SendMessage calls must return when tasks reach interrupted states (input_required, auth_required) in addition to terminal states. This prevents deadlock scenarios where tasks waiting for user input would cause blocking calls to hang indefinitely.

Changes:
- specification/grpc/a2a.proto: Updated blocking field comment to include "terminal or interrupted state"
- specification/grpc/a2a.proto: Fixed AUTH_REQUIRED classification to be an "interrupted state" (consistent with INPUT_REQUIRED)
- docs/specification.md: Updated blocking behavior description to include interrupted states and changed "final task state" to "current task state"

This enables proper client workflows where blocking calls can return on INPUT_REQUIRED or AUTH_REQUIRED, allowing clients to provide the needed information and resume with subsequent SendMessage calls.

Fixes a2aproject#1264

Co-Authored-By: madankumarpichamuthu <madankumarpichamuthu@users.noreply.github.com>
@madankumarpichamuthu madankumarpichamuthu requested a review from a team as a code owner January 22, 2026 21:05
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Summary of Changes

Hello @madankumarpichamuthu, 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 clarifies the specification for blocking SendMessage calls to ensure they return when a task enters an input_required or auth_required state. This change is crucial for preventing deadlocks in client workflows where tasks require external input or authentication, allowing clients to respond and continue processing without indefinite waits. The updates ensure that the system's behavior aligns with proper client interaction patterns for interrupted tasks.

Highlights

  • Blocking Call Behavior: Blocking SendMessage calls are now specified to return when a task reaches an input_required or auth_required (interrupted) state, in addition to terminal states. This prevents deadlocks where tasks awaiting user input would cause calls to hang indefinitely.
  • Task State Classification: The AUTH_REQUIRED task state has been explicitly reclassified as an 'interrupted state' for consistency with INPUT_REQUIRED.
  • Documentation Updates: The documentation has been updated to reflect the clarified blocking behavior, including the new interrupted states and changing 'final task state' to 'current task state'.
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Code Review

This pull request provides an important clarification to the specification regarding blocking calls. By specifying that blocking calls must return on interrupted states (input_required, auth_required) in addition to terminal states, you've addressed a potential source of deadlocks for client implementations. The changes in the specification document and the gRPC proto file are consistent and effectively communicate this updated behavior. I have one minor suggestion to further improve the clarity of a comment.

madankumarpichamuthu and others added 2 commits January 22, 2026 14:09
Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>
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@madankumarpichamuthu this is already covered by #1398

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LGTM

@muscariello muscariello merged commit 0655ff3 into a2aproject:main Jan 29, 2026
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darrelmiller pushed a commit that referenced this pull request Mar 12, 2026
🤖 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>
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[Bug]: Handle blocking SendMessage calls needing user interactions

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