chore(compat): CC 2.1.176–181 survey + lift held subagent-nesting wording

[tigers1997]

Summary

Follow-up to #81. The v2.7.0 release held the subagent-nesting wording on a CC 2.1.172 CHANGELOG vs. live-docs contradiction (CHANGELOG said subagents can nest ≤5 levels; live docs said they cannot). The contradiction is now reconciled upstream:

• code.claude.com/docs/en/sub-agents line 786 (min-version: 2.1.172): "a subagent can spawn its own subagents."
• Line 792: foreground subagents are self-limiting at any depth.
• Line 793: background subagents capped at depth 5.
• CC 2.1.181 fix bullet: "Fixed foreground subagents spawning unbounded nested chains; they now respect the same 5-level depth limit as background subagents."

Three shipped wording sites updated:

File	Line	Was	Now
docs/04-subagents-mcp-orchestration.md	59	"Subagents cannot spawn other subagents"	"Subagents can spawn other subagents (CC ≥ 2.1.172, capped at 5 nesting levels). Older CC versions can't. Prefer leaf designs anyway..."
docs/04-subagents-mcp-orchestration.md	140	"Subagents can't spawn subagents. If you need 3 levels, you're designing wrong."	"Subagent nesting caps at 5 levels (CC ≥ 2.1.172; earlier versions: 0). If you need 3+ levels, the design is usually still wrong..."
templates/commands/infinite/SKILL.md	65	"They cannot spawn their own subagents and their contexts don't share."	"Their contexts don't share — even with nested-subagent support (CC ≥ 2.1.172, ≤ 5 levels), a child can't reach a sibling's transcript."

Leaf-design guidance preserved. The /infinite no-sibling-coordination invariant stands because subagent contexts still don't share regardless of whether nesting is available.

2.1.176–181 survey

Verbatim-pull (2.1.177 + 2.1.180 NOT PRESENT in CHANGELOG — skipped or internal-only):

• No new in-territory settings.json keys.
• Out-of-territory by precedent: footerLinksRegexes + language (2.1.176, UI-pref tier), sandbox.allowAppleEvents (2.1.181, macOS-only opt-in).
• Future opt-in stub candidate: Tool(param:value) permission-rule syntax with * wildcard (2.1.178, e.g. Agent(model:opus)). No shipped template uses the form yet; SchemaStore acceptance unverified. Parked for the next compat batch.
• Nested .claude/skills collision handling (2.1.178): <dir>:<name> namespacing on name clash. Reinforces the existing plugin-skill carve-out pattern; no shipped-template impact.
• MCP server-level specs in subagent disallowedTools (mcp__server, mcp__server__*, mcp__*) silently-ignored bug fixed in 2.1.178 — no-exposure grep against shipped templates clean.
• Auto-mode classifier (2.1.178) + miscellaneous subagent UX fixes (2.1.179/181): no configurator action.

Sync gate status

SchemaStore sync PR #5723 (→v2.1.150) unchanged — still open/draft, untouched since 2026-05-24 despite its declared blocker #5728 merging 2026-06-01. tested_up_to stays pinned at 2.1.150 per the no-lone-bumps rule. Compat comment refreshed in config_schema.py with the full 2.1.176–181 survey.

Claude Code compat: 2.1.116–2.1.150 (unchanged).

Test plan

• python3 configure.py --check clean (12 modules, 84 files, compat 2.1.116–2.1.150)
• bash test/cc-manifest/test-whats-new.sh PASS (all four cases A–D)
• Stale-wording grep clean across docs/ + templates/ (no remaining "cannot spawn" claims)
• CI check green
• CI verdict-gate green
• CI license/cla green

🤖 Generated with Claude Code

[claude]

VERDICT: PASS

Clean, well-scoped compat survey. The subagent-nesting wording unblock is correctly supported by dual primary-source evidence (live docs min-version: 2.1.172 + CC 2.1.181 explicit depth-cap unification), all three affected wording sites are updated consistently, and the leaf-design guidance and /infinite no-sibling invariant are preserved. No new in-territory settings.json keys shipped (nothing to cross-check against SchemaStore), no third-party code added (no NOTICE entry needed), ## Unreleased entry present, and the four changed files form a single logical unit with no scope creep.