Remove deprecated task spawn tool

[TheGreatAxios]

Summary

• Removes the deprecated callable task spawn surface so workers dispatch through spawn_agent and wait_agents only.
• Moves local and plugin agent profile dispatch onto spawn_agent(agent=...) so search_agents results remain usable.
• Updates prompts, docs, skills, TUI rendering, telemetry, and capability evals for the split fleet path.

Verification

• \bun test v1.3.14 (0d9b296a) passes

• \ passes

• \ passes

• \Bundled 984 modules in 112ms

  index.js 4.76 MB (entry point)
  highlights-ghv9g403.scm 2.86 KB (asset)
  tree-sitter-javascript-nd0q4pe9.wasm 0.41 MB (asset)
  highlights-eq9cgrbb.scm 9.83 KB (asset)
  tree-sitter-typescript-zxjzwt75.wasm 1.41 MB (asset)
  highlights-r812a2qc.scm 3.44 KB (asset)
  tree-sitter-markdown-411r6y9b.wasm 0.42 MB (asset)
  injections-73j83es3.scm 0.82 KB (asset)
  highlights-x6tmsnaa.scm 2.15 KB (asset)
  tree-sitter-markdown_inline-j5349f42.wasm 0.43 MB (asset)
  highlights-hk7bwhj4.scm 3.48 KB (asset)
  tree-sitter-zig-e78zbjpm.wasm 0.69 MB (asset)
  parser.worker-m4xh6kys.js 172.51 KB (asset)
  tree-sitter-3jzf13jk.wasm 205.49 KB (asset) passes

• \bun test v1.3.14 (0d9b296a)
  rate=15/s [
  [ "we " ], [ "we need" ], [ "we need to chec" ], [ "we need to check wheth" ]
  ]
  rate=20/s [
  [ "we n" ], [ "we need to" ], [ "we need to check whe" ], [ "we need to check whether the c" ]
  ]
  rate=28/s [
  [ "we ne" ], [ "we need to che" ], [ "we need to check whether the" ], [ "we need to check whether the",
  "cache key alr"
  ]
  ]
  rate=40/s [
  [ "we need " ], [ "we need to check whe" ], [ "we need to check whether the", "cache key a" ], [ "we need to check whether the", "cache key already accounts for", "" ]
  ]
  rate=60/s [
  [ "we need to c" ], [ "we need to check whether the c" ], [ "we need to check whether the",
  "cache key already accounts for", ""
  ], [ "we need to check whether the", "cache key already accounts for", "the locale" ]
  ]
  lifecycleStatus: completed retained: false
  resumeOne outcome: {"ok":false,"status":"completed"}
  cancelAll returned: [] | close invoked: true
  sessions retained despite maxRetained=3: 3 passes with 5662 pass / 0 fail

Fixes CL-7081

[linear-code]

CL-7081

[TheGreatAxios]

greybeard · comment
This branch removes the deprecated fused task spawn surface and routes dispatch through spawn_agent plus wait_agents only.

No path:line findings. Approach matches the issue constraints: no compatibility alias, no re-fused wait path, and local/plugin agent profile dispatch remains reachable via spawn_agent(agent=...).

[TheGreatAxios]

critic · comment
This branch removes the deprecated task tool and updates prompts, tests, docs, telemetry, and eval fixtures for the split fleet contract.

No path:line findings. The follow-up prompt fix includes description in the spawn_agent example and removes the nested search_agents recommendation from the orchestrator appendix.

[TheGreatAxios]

primary · would request changes
This branch removes the deprecated task wrapper and makes spawn_agent plus wait_agents the only fleet spawn path.

Findings:

• src/subagent/agent-fleet.ts:926 removes the old long-lived subagent PerfTrace producer. spawn_agent now fires deps.run(params) asynchronously and returns immediately, but nothing opens/closes a subagent span around that promise. The deleted src/perf/permission-subagent-spans.test.ts cases were the only coverage proving completed/failed/worktree-setup-failed workers emitted and closed subagent spans nested under the current turn; meanwhile src/perf/index.ts:89 still advertises subagent as a phase and attribution reports still bucket it. PerfTrace now loses child wall-time attribution for fleet work. Please move equivalent start("subagent")/end(...) coverage to the split spawn_agent path or intentionally remove the phase/reporting contract.