docs(scope): subagent recursion is the harness's job, not skills'

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.out-of-scope/subagent-recursion.md

@@ -0,0 +1,14 @@
+# Guards against sub-agents recursing into skills
+
+Skills do not add guards against sub-agents recursively invoking skills or spawning nested agents (a `/code-review` sub-agent re-invoking `/code-review`, a `/research` agent spawning another agent). Requests to add leaf-agent instructions, depth limits or "do not invoke this skill" lines are out of scope.
+
+## Why this is out of scope
+
+The harness should be responsible for stopping infinite subagent loops, not skills. The harness decides which tools and skills a sub-agent can reach and how deep nesting can go, so a limit set there holds for every skill at once. A guard written into one skill's prose covers only that skill, costs tokens on every run, and still depends on the model choosing to obey it.
+
+If a sub-agent recurses or fans out without bound, report it to the harness.
+
+## Prior requests
+
+- #530: "research skill: spawned background agent can recursively re-spawn another agent (uncontrolled nesting)"
+- #573: "code-review sub-agents recursively invoke /code-review and fan out" (PR #1186, "code-review: make the Standards and Spec sub-agents leaf reviewers", closed)

SCOPE.md

@@ -28,6 +28,7 @@ Each file in [`.out-of-scope/`](./.out-of-scope/) records one rejected concept a
 - [`new-skills.md`](./.out-of-scope/new-skills.md)
 - [`question-limits.md`](./.out-of-scope/question-limits.md)
 - [`setup-skill-verify-mode.md`](./.out-of-scope/setup-skill-verify-mode.md)
+- [`subagent-recursion.md`](./.out-of-scope/subagent-recursion.md)
 
 ## Unclear issues