fix(agents): preserve native child delivery and human answer presentation

[agiontheway]

This checkpoints the fork's 0.0.39 upgrade and cross-provider dispatch fixes. Automatic child completions reach the parent through hidden provider input and remain visible in the native task/Agents interface, without an extra parent user-message bubble. Pending native questions retain their callbacks, and accepted human answers now appear as ordinary chat messages.

Scope and design

• Preserve the existing fork checkpoint at b68655c8 and the prior release upgrade. The ancestry-only reconciliation commit does not change the tree.
• ef18a438: record deterministic internal child-delivery requests and exact input acknowledgements; retain native child task presentation and existing provider continuation.
• 811c58906: record an accepted native human answer through the existing user-message event, on its original turn, without sending the answer twice or creating another provider turn.

The latest corrections change server/internal-contract code and focused tests. They do not change frontend source, provider adapters, the public client command/event interface, mobile applications, dependencies, or historical messages. The full PR includes the older fork upgrade; it is not presented as only the latest small correction.

Validation

• Independent strict reviews passed for the child-delivery and native-answer corrections.
• Focused orchestration, callback-adapter and shared-client tests passed. Server and contracts typechecks passed. Scoped lint retains a verified pre-existing test-only manual-runtime violation and unused-parameter warnings; these are not reported as clean.
• Real packaged-build comparison through Computer Use Chrome covered normal input, automatic child delivery in both provider directions, pending-question survival and answering, Agents cards/navigation, explicit child retrieval and follow-up, stop/recovery, and reload. No regression was observed within that bounded scope; the baseline concurrent-question case was inconclusive because the model declined the fixture.
• The maintainer installed the latest Apple Silicon build, confirmed native and asynchronous answer bubbles, and reported normal use working. This does not claim exhaustive mobile/relay coverage.
• Final DMG from 811c58906a89 passed integrity and arm64 inspection; the bundled server matches the fresh build and retains the previous callback and hidden-delivery fixes. SHA-256: 2bf4e11318da7addd82625c182c835f763cec63db788ea32ba5301eb7be18d2a.

Fork CI status: no required checks or branch-protection rules are configured. The copied Blacksmith jobs are queued without an assigned runner; GitHub CI is not claimed to have passed. The merge gate uses the scoped local validation and independent reviews above.

Evidence and screenshots remain local. No private session transcripts, local test credentials, or screenshots are attached to this public PR. The local build retains ad-hoc signing and is not Developer ID notarized.

Implementation and review: Codex/T3 harness with GPT-6 Astra review; real Claude and Codex providers used for acceptance tests. The maintainer has authorized merging after the privacy sweep, required checks, and blocking-review gates pass.