migrate-spawn-task

Metadata

Description

## Description

Migrate src/commands/spawn_task.rs (the unified entry point) to call workgraph::dispatch::plan_spawn() rather than constructing the executor + model decision ad-hoc.

File scope: src/commands/spawn_task.rs only. Do NOT touch other spawn sites in this subtask.

Implement directly — do not decompose further.

## Validation
- [ ] spawn_task.rs constructs no executor/model decision logic of its own — calls plan_spawn() and consumes plan.executor / plan.model / plan.endpoint
- [ ] Provenance log line emitted on spawn (eprintln! prefixed [spawn_task])
- [ ] cargo build + cargo test pass
- [ ] grep src/commands/spawn_task.rs for direct executor string handling outside plan_spawn → minimal residue (only the plan-consuming wrappers)

Depends on

• done .assign-migrate-spawn-task

Required by

• (none)

Log

• 2026-04-26T20:28:47.313355915+00:00 Lightweight assignment: agent=Careful Programmer (f5143935), exec_mode=full, context_scope=task, reason=Careful Programmer is the only programmer available and Careful tradeoff matches refactoring work requiring correctness and stability; strong prior experience (41 tasks) on similar implementations.
• 2026-04-26T20:44:06.631107841+00:00 Spawned by coordinator --executor claude --model opus
• 2026-04-26T20:44:13.902537622+00:00 Starting: reading spawn_task.rs and dispatch::plan_spawn
• 2026-04-26T20:45:10.271961625+00:00 Reviewing plan_spawn vs spawn_task semantics; key issues: (a) WG_EXECUTOR_TYPE env-var path, (b) endpoint name vs full EndpointConfig, (c) default Native vs Claude. Plan: pass env var as agent_executor; pull endpoint name from plan.endpoint.
• 2026-04-26T20:57:24.058461428+00:00 Build + test pass (1 pre-existing unrelated failure: provenance_full_lifecycle_all_ops_recorded — same as baseline). Spawn_task tests: 11/11 pass.
• 2026-04-26T21:04:00.819666540+00:00 Committed: 798a06625 — pushed to remote
• 2026-04-26T21:04:50.183627610+00:00 Task marked as done