Enable sidebar-visible third-party Worker callbacks and binding readback #156

Priority and external blocker

Priority: P0 — complete the Host/runtime gate before resuming dependent orchestration work.

This is a hard external blocker for NOirBRight/github-work-orchestrator#16. Keep that Issue stopped and unclaimed until the native sidebar-visible Worker acceptance gate below passes.

Sanitized reproduction

Environment: Codex Desktop 26.707.12708.0, Codex CLI 0.144.5, CodexHub route, Ollama Cloud native Responses, requested glm-5.2 / max.

1. A native worktree Worker was created from the parent and appeared as a separate sidebar Task.
2. Parent-to-child continuation worked, and the child had functioning shell/MCP tools.
3. The child could not access a supported parent-result callback or equivalent result-delivery channel. Exact-name searches returned tools=[].
4. The child could not prove the effective agent type, model, and reasoning through supported readback.
5. Without a terminal unsupported result, the failed capability search could repeat. A bounded parent continuation stopped the read-only incident; the child returned BLOCKED and its worktree stayed clean.

Private rollout, Task, callback, local-path, call, and token identifiers remain excluded. Do not edit Codex SQLite or infer evidence from private IDs.

Problem

The Codex Host/runtime does not yet provide a complete supported contract for third-party delegated implementation as a native sidebar-visible Worker Task. The required contract spans Worker materialization, bidirectional parent/Worker communication, result delivery with a confirmable receipt, effective binding readback, explicit unsupported terminalization, and a visible Active → Done lifecycle.

A model-visible callback schema is not sufficient when the child has no registered native handler. Requested settings are not effective binding evidence.

Desired outcome

Native Host/runtime delegation can create a sidebar-visible third-party Worker and prove, before implementation begins, that the supported execution surface and effective binding match the request. The parent and Worker can communicate in both directions, the parent receives a confirmable result receipt, unsupported capabilities stop terminally, and the Worker becomes visibly Active and then Done.

Scope — Host/runtime only

• Materialize delegated implementation as a separate native sidebar-visible Worker Task with supported discovery/readback.
• Register a supported parent-result callback in the Worker context, or provide an equivalent durable result-delivery channel whose receipt the parent can confirm.
• Support parent-to-Worker continuation and Worker-to-parent result return in the same isolated lifecycle.
• Expose supported effective readback for agent type, model, and reasoning effort before edits begin.
• Return an explicit, machine-classifiable terminal unsupported result when the requested Worker surface, callback/result channel, or binding cannot be provided.
• Expose supported lifecycle readback showing the Worker transition from Active to Done.
• Preserve sanitized Host/runtime evidence for a bounded manual replay.

Non-goals

• Do not implement CodexHub's repeated identical empty-tool_search bound; Bound repeated empty tool_search misses for external models #159 owns that work.
• Do not implement CodexHub Worker selector/codec preservation or effective-binding validation; Preserve Worker selector and effective binding validation for external delegation #161 owns that work.
• Do not inject a callback schema without a registered Host/runtime handler.
• Do not substitute GPT, Hidden Subagent, Inline execution, Background process, codex exec, or a shell-launched model for the sidebar-visible Worker.
• Do not edit Codex SQLite, publish private IDs or local paths, synthesize rollout state, or infer binding from requested settings.
• Do not broaden into unrelated transport, routing, retry, apply-patch, or Task-activity rendering work.

Acceptance criteria

• A native delegation materializes one separate sidebar-visible third-party Worker Task.
• Supported readback proves the effective Worker agent type, requested third-party model, and requested reasoning effort before implementation begins.
• Missing, unknown, contradictory, rejected, unsupported, or GPT-substituted binding evidence stops terminally before edits.
• Parent-to-Worker continuation and Worker-to-parent result delivery both succeed in the same isolated Worker lifecycle.
• The parent receives a supported confirmable receipt for the Worker's final result.
• An unavailable Worker surface, callback/result channel, or selector returns an explicit terminal unsupported result rather than continuing or substituting another surface.
• Supported Task APIs show the separate Worker as Active and then Done.
• The real validation performs only a disposable read-only action until surface, binding, and callback/receipt preflight pass.
• No GPT, Hidden Subagent, Inline, Background, codex exec, or shell-launched substitute appears in the evidence.

Host/runtime verification and evidence

This Issue does not authorize or invent CodexHub product-code verification. Its acceptance is manual Host/runtime evidence from one isolated native Codex Desktop replay using a third-party model and requested reasoning:

1. create one native sidebar-visible Worker Task;
2. read back effective Worker agent type, model, and reasoning through supported APIs;
3. send one parent continuation;
4. return one Worker result and confirm the parent receipt;
5. read back Active → Done terminal visibility;
6. capture only sanitized outcome fields and failure classifications.

Relationships

• External hard blocker: NOirBRight/github-work-orchestrator#16
• Broad collaboration verification: 0.1.8 Beta2: Define the Codex CLI 0.146 Collaboration V1/V2 schema boundary #64
• Deferred discovery classification: 0.1.8 Beta3: Complete the generic client tool_search lifecycle #63
• Runtime plan evidence: 0.1.8 Beta2: Inventory Codex CLI 0.146 tool types and representative Responses lifecycles #62
• CodexHub repeated-search child: Bound repeated empty tool_search misses for external models #159
• CodexHub selector/binding child: Preserve Worker selector and effective binding validation for external delegation #161

Expected hotset

Host/runtime-owned, outside this repository:

• native sidebar-visible Worker Task creation/materialization;
• child Host tool registration or equivalent result-delivery channel and receipt;
• supported effective agent/model/reasoning readback;
• supported Worker lifecycle state and explicit unsupported terminalization.

No CodexHub product-code hotset is owned by this Issue.

Execution contract

Execution-Contract: v2
Verification-Class: strict
Verification-Commands: Host/runtime supported-API readback only; no CodexHub product-code command is claimed
Manual-Evidence: one isolated native third-party sidebar-visible Worker replay proving effective binding, bidirectional communication, confirmed parent receipt, explicit unsupported behavior, and Active → Done visibility
Architecture-Decision: resolved
Review-Owner: orchestrator