feat(ultraplan-local): v2.2.0 — /ultra-cc-architect-local

New optional command between /ultraresearch-local and /ultraplan-local that
matches brief+research against Claude Code features (hooks, subagents, skills,
output-styles, MCP, plan-mode, worktrees, background-agents) and produces an
architecture note with brief-anchored rationale plus explicit gaps.

Added:
- commands/ultra-cc-architect-local.md (--project, --fg, --quick, --no-gaps)
- agents/architect-orchestrator.md (opus) — 6-phase background orchestrator
- agents/feature-matcher.md (sonnet) — fallback-ranked feature proposals
- agents/gap-identifier.md (sonnet) — 4 gap classes with issue-ready drafts
- agents/architecture-critic.md (sonnet) — hallucination gate as BLOCKER
- skills/cc-architect-catalog/ — SKILL.md + 10 seed entries (reference/pattern)

Changed (non-breaking):
- commands/ultraplan-local.md — auto-discovers architecture/overview.md
- agents/planning-orchestrator.md — cross-references cc_features_proposed
- plugin.json — 2.1.0 → 2.2.0, description, cc-architecture keyword
- CHANGELOG, README, CLAUDE.md (plugin + marketplace root)

Pipeline becomes brief → research → architect → plan → execute. Architect is
optional; existing project dirs keep working unchanged.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

plugins/ultraplan-local/skills/cc-architect-catalog/subagents-pattern.md

@@ -0,0 +1,103 @@
+---
+name: subagents-pattern
+description: When subagents earn their cost and how to compose them — swarm, pipeline, and guard patterns.
+layer: pattern
+cc_feature: subagents
+source: https://docs.claude.com/en/docs/claude-code/sub-agents
+concept: subagent-composition
+last_verified: 2026-04-18
+ngram_overlap_score: null
+review_status: approved
+---
+
+# Subagents — Pattern
+
+## When to delegate
+
+Delegation earns its cost when at least one of these holds:
+
+- **Context isolation** — the subtask needs to read 50+ files or run
+  many greps, and the parent conversation does not need the raw
+  results. Summaries survive; raw output stays in the subagent.
+- **Parallelism** — multiple independent subtasks can run at once,
+  compressing wall-clock time.
+- **Specialization** — the subagent has a tailored system prompt that
+  changes its behavior meaningfully (e.g., adversarial reviewer).
+- **Tool scoping** — the subtask should run with fewer tools than the
+  parent (principle of least privilege).
+
+If none of these apply, inline the work. A subagent call costs a full
+model turn; do not pay it for routine reads.
+
+## Common patterns
+
+### Pattern A: Exploration swarm
+
+Parent launches 4-8 specialized subagents in parallel, each with a
+narrow brief (architecture, dependencies, risks, tests, ...). Each
+returns a summary. Parent synthesizes.
+
+Used by: `ultraplan-local` Phase 2 exploration.
+
+Cost shape: N × Sonnet call, wall-clock ≈ slowest subagent.
+
+### Pattern B: Adversarial review
+
+Parent writes an artifact (plan, design note). Launches a reviewer
+subagent with a system prompt that demands problems, never praise.
+Reviewer returns findings. Parent revises.
+
+Used by: `plan-critic`, `scope-guardian`, `architecture-critic`.
+
+Cost shape: 1 × Sonnet call per review pass.
+
+### Pattern C: Background orchestrator
+
+Parent kicks off a long-running orchestrator subagent with
+`run_in_background: true`, then continues. Orchestrator runs its own
+subagents, synthesizes, writes output to disk. Parent is notified on
+completion.
+
+Used by: `planning-orchestrator`, `research-orchestrator`.
+
+Cost shape: 1 × Opus orchestrator + N × Sonnet workers. Overlaps with
+other user work.
+
+### Pattern D: Guard subagent
+
+A hook delegates an "is this safe?" question to a subagent when the
+answer needs judgment. The subagent returns a verdict; the hook
+enforces it.
+
+Cost shape: 1 × Sonnet call per hook invocation. Use sparingly —
+adds seconds of latency per tool call.
+
+## Pitfalls
+
+- **Delegate-understanding anti-pattern** — do not write "based on your
+  findings, fix the bug" to a subagent. The subagent is not inside your
+  head; it cannot see what you synthesized. Pass concrete context.
+- **Prompt-on-top-of-prompt drift** — if the parent's prompt to a
+  subagent contradicts the subagent's own system prompt, the subagent
+  follows its system prompt. Do not try to re-style a reviewer into a
+  cheerleader by prompting harder.
+- **Silent failure** — a subagent that returns "done" without evidence
+  may have done nothing. Trust but verify: check for the concrete
+  artifacts the subagent was asked to produce.
+- **Orchestration explosion** — a three-level-deep subagent tree costs
+  exponentially. Flatten wherever the inner levels don't need their own
+  context isolation.
+- **Token budget fights** — parent and all active subagents share the
+  harness's overall budget. Cap subagent output length ("report in
+  under 200 words") when the summary is what matters.
+
+## Composition with other features
+
+- Subagents + hooks: hooks fire during subagent tool calls too. A
+  subagent with only `Read` tools is already constrained; hooks add
+  defense in depth.
+- Subagents + worktrees: an `isolation: "worktree"` subagent works in
+  an isolated copy of the repo, so its writes never clash with the
+  parent's writes.
+- Subagents + background: run heavy exploration in background while the
+  user continues other work.