feat: Implement Architect role & design_task tool (#189)

Adds the Architect role for design/architecture investigations with
persistent sessions and structured design proposals.

## New Features

- **Architect role** with opus (complex) and sonnet (standard) levels
- **design_task tool** — Creates To Design issues and dispatches architect
- **Workflow states:** To Design → Designing → Planning
- **Completion rules:** architect:done → Planning, architect:blocked → Refining
- **Auto-level selection** based on complexity keywords

## Files Changed (22 files, 546 additions)

### New Files
- lib/tools/design-task.ts — design_task tool implementation
- lib/tools/design-task.test.ts — 16 tests for architect functionality

### Core Changes
- lib/tiers.ts — ARCHITECT_LEVELS, WorkerRole type, models, emoji
- lib/workflow.ts — toDesign/designing states, completion rules
- lib/projects.ts — architect WorkerState on Project type
- lib/dispatch.ts — architect role support in dispatch pipeline
- lib/services/pipeline.ts — architect completion rules
- lib/model-selector.ts — architect level selection heuristic

### Integration
- index.ts — Register design_task tool, architect config schema
- lib/notify.ts — architect role in notifications
- lib/bootstrap-hook.ts — architect session key parsing
- lib/services/tick.ts — architect in queue processing
- lib/services/heartbeat.ts — architect in health checks
- lib/tools/health.ts — architect in health scans
- lib/tools/status.ts — architect in status dashboard
- lib/tools/work-start.ts — architect role option
- lib/tools/work-finish.ts — architect validation
- lib/tools/project-register.ts — architect labels + role scaffolding
- lib/templates.ts — architect instructions + AGENTS.md updates
- lib/setup/workspace.ts — architect role file scaffolding
- lib/setup/smart-model-selector.ts — architect in model assignment
- lib/setup/llm-model-selector.ts — architect in LLM prompt

lib/tools/design-task.test.ts

@@ -0,0 +1,105 @@
+/**
+ * Tests for architect role, design_task tool, and workflow integration.
+ * Run with: npx tsx --test lib/tools/design-task.test.ts
+ */
+import { describe, it } from "node:test";
+import assert from "node:assert";
+import { parseDevClawSessionKey } from "../bootstrap-hook.js";
+import { isArchitectLevel, levelRole, resolveModel, defaultModel, levelEmoji } from "../tiers.js";
+import { selectLevel } from "../model-selector.js";
+import {
+  DEFAULT_WORKFLOW, getQueueLabels, getActiveLabel, getCompletionRule,
+  getCompletionEmoji, detectRoleFromLabel, getStateLabels,
+} from "../workflow.js";
+
+describe("architect tiers", () => {
+  it("should recognize architect levels", () => {
+    assert.strictEqual(isArchitectLevel("opus"), true);
+    assert.strictEqual(isArchitectLevel("sonnet"), true);
+    assert.strictEqual(isArchitectLevel("medior"), false);
+  });
+
+  it("should map architect levels to role", () => {
+    assert.strictEqual(levelRole("opus"), "architect");
+    assert.strictEqual(levelRole("sonnet"), "architect");
+  });
+
+  it("should resolve default architect models", () => {
+    assert.strictEqual(defaultModel("architect", "opus"), "anthropic/claude-opus-4-5");
+    assert.strictEqual(defaultModel("architect", "sonnet"), "anthropic/claude-sonnet-4-5");
+  });
+
+  it("should resolve architect model from config", () => {
+    const config = { models: { architect: { opus: "custom/model" } } };
+    assert.strictEqual(resolveModel("architect", "opus", config), "custom/model");
+  });
+
+  it("should have architect emoji", () => {
+    assert.strictEqual(levelEmoji("architect", "opus"), "🏗️");
+    assert.strictEqual(levelEmoji("architect", "sonnet"), "📐");
+  });
+});
+
+describe("architect workflow states", () => {
+  it("should include To Design and Designing in state labels", () => {
+    const labels = getStateLabels(DEFAULT_WORKFLOW);
+    assert.ok(labels.includes("To Design"));
+    assert.ok(labels.includes("Designing"));
+  });
+
+  it("should have To Design as architect queue label", () => {
+    const queues = getQueueLabels(DEFAULT_WORKFLOW, "architect");
+    assert.deepStrictEqual(queues, ["To Design"]);
+  });
+
+  it("should have Designing as architect active label", () => {
+    assert.strictEqual(getActiveLabel(DEFAULT_WORKFLOW, "architect"), "Designing");
+  });
+
+  it("should detect architect role from To Design label", () => {
+    assert.strictEqual(detectRoleFromLabel(DEFAULT_WORKFLOW, "To Design"), "architect");
+  });
+
+  it("should have architect:done completion rule", () => {
+    const rule = getCompletionRule(DEFAULT_WORKFLOW, "architect", "done");
+    assert.ok(rule);
+    assert.strictEqual(rule!.from, "Designing");
+    assert.strictEqual(rule!.to, "Planning");
+  });
+
+  it("should have architect:blocked completion rule", () => {
+    const rule = getCompletionRule(DEFAULT_WORKFLOW, "architect", "blocked");
+    assert.ok(rule);
+    assert.strictEqual(rule!.from, "Designing");
+    assert.strictEqual(rule!.to, "Refining");
+  });
+
+  it("should have architect completion emoji", () => {
+    assert.strictEqual(getCompletionEmoji("architect", "done"), "🏗️");
+    assert.strictEqual(getCompletionEmoji("architect", "blocked"), "🚫");
+  });
+});
+
+describe("architect model selection", () => {
+  it("should select sonnet for standard design tasks", () => {
+    const result = selectLevel("Design: Add caching layer", "Simple caching strategy", "architect");
+    assert.strictEqual(result.level, "sonnet");
+  });
+
+  it("should select opus for complex design tasks", () => {
+    const result = selectLevel("Design: System-wide refactor", "Major migration and redesign of the architecture", "architect");
+    assert.strictEqual(result.level, "opus");
+  });
+});
+
+describe("architect session key parsing", () => {
+  it("should parse architect session key", () => {
+    const result = parseDevClawSessionKey("agent:devclaw:subagent:my-project-architect-opus");
+    assert.deepStrictEqual(result, { projectName: "my-project", role: "architect" });
+  });
+
+  it("should parse architect sonnet session key", () => {
+    const result = parseDevClawSessionKey("agent:devclaw:subagent:webapp-architect-sonnet");
+    assert.deepStrictEqual(result, { projectName: "webapp", role: "architect" });
+  });
+});