fix(codex): correct multi-agent guidance against Codex source

Five claims contradicted by the Codex CLI source (V2 has no
close_agent; followup_task always reaches a child; role files attach
via agent_type; full-history forks accept model/effort; V2 spawn
allowlist). Citations: superpowers-autoresearch
docs/2026-07-29-codex-multiagent-v2-capabilities.md.

skills/using-superpowers/references/codex-tools.md

@@ -7,7 +7,34 @@ Add to your Codex config (`~/.codex/config.toml`):
 multi_agent = true
 ```
 
-This enables `spawn_agent`, `wait_agent`, and `close_agent` for skills like `dispatching-parallel-agents` and `subagent-driven-development`. When using subagent-driven-development, close reviewer subagents when their review returns. Keep each implementer subagent open until its task's review passes — the fix loop resumes the implementer — then close it. If your harness cannot send another message to a spawned agent, dispatch each fix round as a fresh implementer carrying the brief, the report file, and the findings.
+This enables the multi-agent tools that skills like
+`dispatching-parallel-agents` and `subagent-driven-development` use.
+Which tools you get depends on the multi-agent version your model
+preset selects (current presets run V2; older ones run V1). Trust your
+actual tool list over any table — including this one — when they
+disagree.
+
+- **Spawning:** give children a clean context with
+  `spawn_agent {fork_turns: "none"}`; the default `"all"` copies your
+  entire transcript into the child. On Codex 0.145+, role files under
+  `~/.codex/agents/` attach to isolated forks via `agent_type`.
+  Full-history forks accept `model` and `reasoning_effort` overrides
+  (only `agent_type` is refused there) — isolated forks are the SDD
+  default for context hygiene, not because overrides require them.
+- **Fix rounds:** resume the implementer with `followup_task` — it
+  delivers your message, triggers a turn, and transparently reloads a
+  child the harness evicted. Never dispatch a fresh implementer on the
+  theory that a spawned agent cannot be messaged again; on V2 it
+  always can.
+- **Lifecycle:** V2 has no `close_agent`. Finished children are
+  evicted automatically when slots are needed; leaving them unclosed
+  costs nothing. Only V1 sessions have `close_agent` — there, close
+  reviewers when their review returns, and close each implementer
+  after its task's review passes.
+- **Model names:** never copy a model name from a skill, table, or old
+  session into `spawn_agent` without checking it against your current
+  spawn allowlist — V2 accepts only V2-capable presets and hard-errors
+  on the rest.
 
 ## Environment Detection