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>

skills/cc-architect-catalog/background-agents-reference.md

@@ -0,0 +1,106 @@
+---
+name: background-agents-reference
+description: CC background agents — long-running subagents with run_in_background and Monitor for progress streaming.
+layer: reference
+cc_feature: background-agents
+source: https://docs.claude.com/en/docs/claude-code/background-agents
+concept: async-agents-and-monitoring
+last_verified: 2026-04-18
+ngram_overlap_score: null
+review_status: approved
+---
+
+# Background Agents — Reference
+
+A background agent is a subagent launched with `run_in_background:
+true`. The parent does not block on its return; instead, the harness
+notifies the parent when the agent completes. Useful for long-running
+exploration, orchestration, and work that overlaps with user activity.
+
+## Launching
+
+```
+Agent({
+  description: "...",
+  subagent_type: "...",
+  prompt: "...",
+  run_in_background: true
+})
+```
+
+The Agent tool returns a handle (agent ID / name). The parent
+continues its turn; no wait.
+
+## Monitoring
+
+Two complementary tools work with background agents:
+
+- **Monitor** — streams updates from a named background process. Each
+  event line arrives as a notification. Used for long-running Bash
+  processes (and, in newer builds, some agent streaming paths).
+- **Completion notifications** — the harness posts a message to the
+  parent when the background agent finishes. The parent sees it as a
+  system-reminder / notification on its next turn.
+
+## When background is worth it
+
+- **Overlapping work** — orchestrator runs 30+ minutes of research
+  while the user continues coding. Without background, the user is
+  blocked the whole time.
+- **Parallel waves** — wave N of sessions running concurrently; the
+  parent collects results as they arrive.
+- **Long-running processes** — an agent waiting on a build, test run,
+  or deployment.
+
+## When background hurts
+
+- **Short tasks** — agent returns in 10 seconds; making it async adds
+  overhead for no gain.
+- **Tight coupling** — if the parent needs the result before doing
+  anything else, background is just foreground with extra steps.
+- **Unbounded token spend** — a background agent with no budget
+  signaling can run until it hits limits. Cap explicitly.
+
+## Common shapes
+
+### Shape A: Orchestrator handoff
+
+Parent interviews user, writes a spec, launches a background
+orchestrator with the spec path. Parent exits its turn; orchestrator
+takes over for the heavy phases.
+
+Used by: `ultraplan-local`, `ultraresearch-local`.
+
+### Shape B: Parallel waves
+
+Parent decomposes work into N independent sessions, launches them all
+in parallel with `run_in_background: true`, then synthesizes returns
+as they arrive.
+
+Used by: `ultraplan-local --decompose` execution.
+
+### Shape C: Watcher
+
+A background agent polls a process (build, test, deploy) and reports
+status changes. Uses Monitor for streaming.
+
+## Pitfalls
+
+- **Lost context** — if the parent conversation ends before the
+  background agent completes, the result may be orphaned. Persist to
+  disk, not memory.
+- **Notification fatigue** — too many background agents = too many
+  reminders interrupting the parent's flow.
+- **Debugging** — background agents run out of the user's view; their
+  failures can be silent. Log to files, not just return messages.
+
+## Composition
+
+- Background + worktrees: the canonical pattern for parallel
+  implementation — each background agent in its own worktree, no
+  clashes.
+- Background + subagents: an orchestrator IS a subagent; it in turn
+  can launch its own subagents (foreground inside the orchestrator's
+  context, or further background).
+- Background + hooks: hooks fire inside the background agent's tool
+  calls, same as foreground.