CHANGELOG.md

Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

[Unreleased]

Fixed

• Protocol diagnostics now redact credential-shaped values in request and response bodies as well as headers. Workflow failure and callback logs also redact credential-shaped exception text; registry search no longer logs raw intent.
• Standard A2A HTTP and SSE error envelopes retain their status, reason, retry hint and safe details. An empty response stream fails immediately with a2a.empty_stream instead of returning an unattributed unsuccessful result.
• A malformed subtask input, an activated extension missing from AgentCard, or an unavailable explicitly preferred protocol now fails before dispatch. Explicit TLS/mTLS/CRL options are rejected for unsupported non-HTTP transports instead of being silently ignored.
• Hosts may inject credential_encryption_key into A2ATransport rather than depending on a process-wide A2AT_CRED_KEY; the environment remains the compatibility fallback.
• MessageContent.with_extension(uri) offers an immutable, Java-aligned way to activate one extension for a single request.
• Registry and PSOP HTTP helpers accept separate connect/read timeout settings instead of hard-coding both to 30 seconds.
• A notification stream that died was never released, and a healthy one could be reported as dead. Liveness was judged from decoded business events only, but an SSE comment heartbeat never reaches the protocol layer, so a subscription receiving only heartbeats looked identical to a dead one -- is_healthy() returned false and a caller acting on it tore down a live stream, while a genuinely dead stream leaked its connection and task forever. Transport activity is now observed per body chunk and recorded separately from business events.
• Sensitive header names were only redacted in the exact spelling the pattern happened to list: api_key, x_api_key, access_session, accessSession, pwd and passwd all leaked into the opt-in protocol log, while api-key and ApiKey were caught. Names are now matched after stripping - and _, and a header registered through register_sensitive_header matches in any spelling.
• A merge step could start before its own predecessor had run. Step readiness was judged from direct predecessors, and a predecessor that had not been activated yet was filtered out entirely -- so a merge whose branches became ready in different batches ran early, with only part of its inputs, and still reported success. Readiness is now judged from all active ancestors, matching the Java engine (WorkflowExecutor#getAllPredecessors): an ancestor that is activated but has not produced output is the signal that a branch is still running.
• A Negotiation-T Propose carried on a taskless bare message (A2A-T pre-task negotiation, where the remote proposes before creating any task) was returned to the host as if it were the final business answer: SendMessageResult.is_success reported success and outputs() exposed the negotiation prompt as the result. Such a message now opens a negotiation, correlated by contextId, and the follow-up send carries no taskId. A bare message whose Negotiation-T metadata is malformed now fails loudly instead of silently passing as a result.
• When an intermediary (API gateway, load balancer) closed an idle SSE stream while the remote task was still running, the engine cancelled that task. A transport fault during stream consumption now falls back to polling get_task every task_poll_interval_seconds until the task leaves a non-terminal state or the deadline expires, so a healthy task is awaited instead of destroyed. Cancellation for a genuinely local interaction failure is unchanged.
• A Notification-T subscription whose remote never acknowledged stayed pending forever, pinning the caller's coroutine and the connection. The first acknowledgement is now bounded by notification_ack_timeout_seconds (default 300s); SSE idleness after the acknowledgement is deliberately not bounded.
• sse_normalization patched json_format.Parse with a duplicate keyword argument, so every StreamResponse text parse raised TypeError. The patch now covers only ParseDict, the entry point that actually performs the normalization, which leaves Parse untouched for every other caller.
• A task stream event carries a full task snapshot, yet its artifact text was appended on every update, duplicating the response text. Text is now assembled once from the merged artifact map, which also gives a non-empty result to streams that deliver content only through artifact_update events.
• subscribe_to_task replaced its accumulated message list on every task event, silently dropping standalone messages seen earlier. It now merges, and additionally reports status and artifact updates and terminal failure codes, matching consume_stream.
• create_ssl_context silently discarded the CA, mTLS and CRL arguments when verify_server=False. A client identity is now still presented, while a trust store or CRL without verification is rejected rather than ignored.
• Protocol logging redacted headers by name pattern alone, so a credential in a custom auth_header was logged in clear. Authentication interceptors now register the exact header names they inject.
• failure_mapping looked the A2A error mapping up by exact type, so a raised subclass fell through to the generic failure code. It now walks the MRO.
• env_file_loader wrote any key from a .env file into the process environment; keys must now be valid environment-variable names.

Changed

• Remote A2A error_details now uses Java-compatible httpStatus, code, status, reason, domain, details and retryAfter fields. Callers using the former http_status or top-level SDK metadata fields must migrate.
• NotificationHeartbeat.last_event_at now reports the last transport activity, including an SSE comment heartbeat, and event_count counts only decoded A2A business events. The last business event is available through the new last_business_event_at. This matches the Java engine's NotificationSubscription.
• NotificationSubscription.is_healthy() judges liveness from transport activity, so a subscription that is only receiving heartbeats is no longer reported as dead. A freshly opened subscription counts as healthy, since opening the stream is activity.
• A notification stream is now released after send_timeout_seconds without any transport activity (configurable through ExtensionSender(notification_idle_timeout_seconds=...)), mirroring the Java engine's idle budget. await subscription.completion raises TimeoutError when that happens. A stream that keeps receiving heartbeats is never released. Hosts that relied on a subscription staying open forever must be updated.
• A2ATransport accepts task_poll_interval_seconds (default 20s, floor 0.1s) and notification_ack_timeout_seconds (default 300s), and execute_psop forwards the former. These mirror the Java engine's taskPollIntervalMillis and notificationAckTimeoutSeconds; the poll interval is used only after a stream interruption, never while the SSE stream is alive.
• consume_stream includes task_id in the AGENT_STATUS_UPDATE intermediate event it forwards, so a caller can learn the remote task identity before a stream ends and recover from a dropped connection.
• A2ATransport caches one A2A client per agent through the new client_for(agent_name) instead of rebuilding it for every send, task poll and cancellation. update_agent_cards drops the cache.
• A2ATransport.get_extension_uris is the public form of the former private _get_extensions, which ExtensionSender reached into across modules.
• WorkflowEngineClient.stream_message accepts timeout_seconds and bounds the whole stream rather than relying on the idle read timeout alone.
• credential_crypto accepts an optional aad that binds a ciphertext to its context. It defaults to None to stay wire-compatible with the Java SDK.
• Registry helpers accept a custom CA, mTLS identity and CRL, and RegistryClient accepts an access token, so the registry path no longer has less TLS capability than the transport path.
• workflow_engine.__version__ is the single source of the distribution version (pyproject.toml reads it through [tool.setuptools.dynamic]), and the a2a-t-sdk lower bound now matches what verify_sdk.py asserts.

Removed

• Dead A2ATransport._text_from_metadata, and a stale extension_handlers.cpython-312.pyc whose source was deleted in 0.0.9.

[0.1.0] - 2026-09-18

Changed

• Publish PyPI releases through the tag-triggered GitHub Actions workflow.
• Upgrade GitHub Actions dependencies for checkout, Python setup, and dependency review.

[0.0.9] - 2026-09-18

Changed

• Align the business callback contract with the Java engine: callbacks prepare final content and never receive the transport client.
• Replace rendered Markdown predecessor context with typed WorkflowInput and ordered task outputs.
• Evaluate every conditional outgoing edge independently; unconditional edges always pass and a node may activate zero through N successors.
• Integrate a2a-t-sdk>=1.0.9,<2 core metadata types while keeping content generation and semantic validation in host code; remove implicit Task-T handlers and legacy negotiation schemas.
• Install development dependencies directly through the editable dev extras and remove the temporary bootstrap file.

Added

• Structured response evidence, protocol-to-business result mapping, safe BusinessFailure, and standard A2A error mapping.
• Remote get_task, list_tasks, cancel_task, and subscribe_to_task operations.
• Explicit NotificationSubscription acknowledgement, completion, close, heartbeat, and health lifecycle.
• mTLS/CRL transport configuration and fail-closed TLS file validation.
• Reusable per-agent credential profiles with nested overrides and fail-fast configuration checks.

Fixed

• Preserve message, task, and artifact metadata at their original levels and process status/artifact stream updates.
• Detect duplicate graph edges, invalid history sources, duplicate AgentCards, and conflicting authentication headers.
• Use the current A2A interceptor contract so activated extension and complete authentication requirement headers reach the wire.
• Close only resources owned by the high-level runner.
• Read canonical negotiationContext metadata and enforce current Propose/Accept/Reject/Abort context and round rules.
• Serialize protobuf message parts as their JSON fields in workflow events instead of leaking descriptor internals.

[0.0.3] - 2026-08-10

Fixed

• NegotiationTHandler metadata overwrite bug: Use local metadata dict to prevent cross-handler contamination
• Negotiation concern extraction: Add fallback in engine_client for concern extraction when metadata is missing
• needResponse=false handling: Fix negotiation flow to properly handle terminal negotiation states

[0.0.2] - 2026-08-06

Fixed

• Task-T prompt caching: TaskTHandler now caches generated prompts by message_text, so identical task descriptions sent to multiple agents only call the LLM once (subsequent agents get cache hit, saving ~20s each)

Added

• Per-handler timing logs: _run_before_send_handlers now logs each handler's execution time individually (e.g. TaskTHandler.before_send for AgentX: 0.01s)

[0.0.1] - 2026-08-06

Initial release of workflow-exec-engine (renamed from internal a2at-engine).

Features

• A2ATransport: shared wire layer with httpx client, auth manager, agent-card map, and SSE stream consumer
• WorkflowEngineClient: workflow send facade with Task-T prompt generation, Negotiation-T auto-loop, event callback
• ExtensionSender: one-shot pre-positioning facade for Authorization-T and Notification-T
• ControlPoint: flow decision interface (on_task / on_self_task / on_route / on_negotiation)
• NegotiationStrategy: pluggable clarification strategy
• SELF_LOOP step type for local task handling without A2A-T message
• ANY_SUCCESS step policy with early cancellation of remaining subtasks
• Parallel DAG step dispatch and context assembly (ContextBuilder)
• Agent authentication from AgentCard securitySchemes (Bearer, custom headers)
• SSE response normalization for non-standard server responses
• RegistryClient for fetching AgentCards and PSOP workflows