Drift sync with upstream agent-framework through 2026-08-31

[jamiewest]

Weekly /drift sync. Reviews the seven upstream dotnet/src commits since the 92aec78c (2026-08-25) pin and advances upstream-sync to 0822dd74 (2026-08-31).

Upstream commits reviewed

PR#	Date	Change	Classification
#7911	2026-08-27	Add timeout for wait-for-first-completion	port
#7913	2026-08-27	ChatMessage input overload on the shared workflow sample runner	skip (propose) — recorded in PORTING.md
#7935	2026-08-31	Add public API analyzers	out of scope (baseline .txt only, no .cs)
#3932	2026-08-31	Cosmos DB Emulator startup reliability	out of scope (CosmosNoSql not ported)
#6046	2026-08-31	ADR renumbering	out of scope (Hyperlight README)
#7932	2026-08-28	Fix duplicate Foundry AgentHost port binding	out of scope (Foundry.Hosting not ported)
#7864	2026-08-26	Annotate DevUI aggregator analyzer false positives	out of scope (Aspire.* not ported)

Totals: 1 ported, 1 skip recorded, 5 out of scope. Suppressed by the PORTING.md ledger: 0 — nothing in this window re-surfaced an existing divergence.

Ported — #7911

BackgroundAgentsProviderOptions gains waitTimeout (default five minutes) plus the defaultWaitTimeout / maximumWaitTimeout bounds, validated in the BackgroundAgentsProvider constructor. BackgroundAgents_WaitForFirstCompletion now races the first-completion future against that timeout; when it elapses the tool returns a message saying the tasks are still running and the tool may be called again, leaving the background work untouched. The timeout stays provider-controlled — the tool's schema still exposes only taskIds.

Dart's Future.timeout is the exact analogue of upstream's Task.WhenAny(firstCompletion, Task.Delay(...)) + timeoutCts.Cancel(): it never cancels the future it wraps, so the tasks keep running. Abandoning the losing Future.any is safe here because BackgroundAgentRuntimeTask.completion is documented never to complete with an error.

Deviations, recorded in PORTING.md:

• ArgumentOutOfRangeException → ArgumentError.value (Dart has no range-specific subtype).
• maximumWaitTimeout keeps upstream's uint.MaxValue - 1 ms value even though that cap is a .NET Task.Delay constraint, so the validated option range matches upstream (and web Timer delays overflow past 2³¹ ms anyway).
• The timeout message reproduces C# TotalSeconds:g through a small _formatSeconds helper.

Upstream's six new unit tests are mirrored in background_agents_provider_test.dart.

Skipped — #7913

The ChatMessage input overload landed in dotnet/src/Shared/Workflows/Execution/WorkflowRunner.cs: an internal sealed Console/stdin sample harness in namespace Shared.Workflows that targets the out-of-scope Workflows.Declarative project. dotnet/src/Shared/Workflows is not part of any ported namespace — workflows/execution/ maps to Microsoft.Agents.AI.Workflows, not to Shared/. PORTING.md now records that future runs classify dotnet/src/Shared/Workflows/** as out of scope.

Extensions edge (drift.md Step I2.5)

1. Upstream MEAI bump — none. Microsoft.Extensions.AI* is 10.9.0 (10.6.0 for .OpenAI) at both the pin and main, so no coordination with the extensions repo is needed for this window.
2. Published-version lag — cleared. extensions ^0.6.0 → ^0.7.1 in both packages, and extensions_flutter ^0.5.0 → ^0.5.2 in agents_flutter. Both packages analyze and test clean against the new resolution; no call sites needed adaptation.
3. Blocked on extensions — nothing. No port in this window needed an API package:extensions does not expose.

Releases

Since this changes code under packages/agents/lib, and both packages' extensions constraints moved:

• agents 2.0.0 → 2.1.0 (minor: new public API on BackgroundAgentsProviderOptions)
• agents_flutter 0.8.2 → 0.8.3 (patch: dependency constraints only)

Each has a matching CHANGELOG entry. agents_flutter's agents: ^2.0.0 constraint still covers 2.1.0 and was left alone.

Verification

• packages/agents: dart analyze clean (2 pre-existing use_super_parameters infos in summarization_compaction_strategy.dart and chat_protocol_executor.dart, both untouched here), dart test — 1196 passed.
• packages/agents_flutter: flutter analyze — no issues, flutter test — 835 passed.
• Toolchain: Flutter 3.47.2 / Dart 3.13.2 stable.

Ripple not verified here: the sibling agents_llama and agents_app checkouts are not available in this cloud environment. Both pin this repo by commit, so the extensions ^0.7.1 bump and the new BackgroundAgentsProviderOptions surface should be checked on their next ref bump. No base contract changed, so subclass breaks are unlikely.

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