feat: add strategy abstraction with pdca and pipeline strategies

skills/orchestration/SKILL.md

@@ -7,6 +7,58 @@ description: Use when executing a multi-agent orchestration — spawning archety
 
 This skill guides you through running a full ArcheFlow orchestration using Claude Code's native Agent tool and git worktrees.
 
+## Strategy Selection
+
+A **strategy** defines the shape of an orchestration run — which phases execute, in what order, and when to iterate. A **workflow** (fast/standard/thorough) controls the depth within a strategy.
+
+### Available Strategies
+
+| Strategy | Flow | When to Use |
+|----------|------|-------------|
+| `pdca` | Plan -> Do -> Check -> Act (cyclic) | Refactors, thorough reviews, multi-concern tasks |
+| `pipeline` | Plan -> Implement -> Spec-Review -> Quality-Review -> Verify (linear) | Bug fixes, fast patches, single-concern tasks |
+| `auto` | Selected by task analysis | Default — let ArcheFlow decide |
+
+### Strategy Interface
+
+Every strategy defines:
+
+- **Phases** — ordered list of execution stages
+- **Agent mapping** — which archetypes run in each phase
+- **Transition rules** — conditions for moving between phases
+- **Iteration model** — cyclic (PDCA) or linear (pipeline)
+- **Exit conditions** — when the run terminates
+
+### PDCA Strategy
+
+The existing orchestration flow (Steps 0-4 below). Cyclic — the Act phase can feed back to Plan for another iteration. Best for tasks requiring multiple review perspectives and iterative refinement.
+
+### Pipeline Strategy
+
+Linear flow with no cycle-back. Faster for well-understood tasks where one pass is sufficient.
+
+| Phase | Agent | Purpose |
+|-------|-------|---------|
+| Plan | Creator | Design proposal |
+| Implement | Maker | Build in worktree |
+| Spec-Review | Guardian, then Skeptic | Security + assumption check (sequential) |
+| Quality-Review | Sage | Code quality review |
+| Verify | (automated) | Run tests, apply targeted fix if CRITICAL |
+
+No cycle-back — WARNINGs are logged but do not block. CRITICALs in Verify trigger a single targeted fix attempt by the Maker, not a full cycle.
+
+### Auto-Selection Rules
+
+When `strategy: auto` (default):
+
+- Task contains "fix", "bug", "patch", "hotfix" → `pipeline`
+- Task contains "refactor", "redesign", "review" → `pdca`
+- Workflow is `thorough` → `pdca` (always)
+- Workflow is `fast` with single file → `pipeline`
+- Otherwise → `pdca`
+
+---
+
 ## Step 0: Choose a Workflow
 
 If `.archeflow/teams/<name>.yaml` exists, the user can reference a team preset: `"Use the backend team"`. Load the preset's phase config instead of built-in defaults. See `archeflow:custom-archetypes` skill for preset format.