feat(P04): Add IDEATE stage to orchestrator pipeline — IDEATE-16

- Add ideation-agent to STAGE_AGENT_MAP for ideate stage
- Implement ideate case in executeStage() with mechanical ideation,
  config-aware category filtering, idea deduplication, auto-accept,
  and ---ci--- commit with decision block
- Add test verifying ideate position between research and plan in
  STAGE_ORDER
- 542 tests passing

src/agents/orchestrator.ts

@@ -47,6 +47,7 @@ export class OrchestratorAgent extends BaseAgent {
 
   private static readonly STAGE_AGENT_MAP: Partial<Record<PipelineStage, AgentName[]>> = {
     research: ["researcher"],
+    ideate: ["ideation-agent"],
     plan: ["planner"],
     execute: ["executor", "code-reviewer", "security-auditor"],
     test: ["tester"],
@@ -571,6 +572,64 @@ export class OrchestratorAgent extends BaseAgent {
         break;
       }
 
+      case "ideate": {
+        this.log("Running ideation stage...");
+        const { IdeationEngine } = await import("../core/ideation.js");
+        const ideationEngine = new IdeationEngine(context.project_path);
+        const ideas = ideationEngine.runMechanical();
+
+        const ideationConfig = this.config.ideation;
+        if (ideationConfig?.categories && ideationConfig.categories.length > 0) {
+          const categoryIdeas = ideationEngine.runMechanical(ideationConfig.categories);
+          const seenTitles = new Set(ideas.map((i) => i.title));
+          for (const idea of categoryIdeas) {
+            if (!seenTitles.has(idea.title)) {
+              ideas.push(idea);
+              seenTitles.add(idea.title);
+            }
+          }
+        }
+
+        ideas.sort((a, b) => b.confidence - a.confidence);
+
+        const maxIdeas = ideationConfig?.max_ideas || 20;
+        const trimmedIdeas = ideas.slice(0, maxIdeas);
+
+        if (this.config.git.auto_commit && this.gitContext!.isGitRepo()) {
+          const { accepted: savedIdeas, results } = ideationEngine.acceptIdeas(trimmedIdeas);
+          const savedCount = results.filter((r) => r.addedToRequirements || r.addedToRoadmap).length;
+
+          const ideationCommit = CommitBuilder.buildDecisionCommit({
+            phase: this.pipelineState!.current_phase,
+            milestone: this.currentMilestone,
+            subject: `ideation results — ${trimmedIdeas.length} total, ${savedCount} accepted`,
+            decisions: savedIdeas.map((idea) => ({
+              id: idea.id,
+              decision: idea.title,
+              rationale: idea.rationale,
+              confidence: idea.confidence,
+              alternatives: idea.actions,
+            })),
+          });
+
+          try {
+            execSync(`git add -A && git commit -m "${ideationCommit.replace(/"/g, '\\"')}" --allow-empty`, {
+              cwd: context.project_path,
+              stdio: "pipe",
+            });
+          } catch (err) {
+            this.warn(`Ideation commit failed: ${err instanceof Error ? err.message : String(err)}`);
+          }
+
+          artifactsCreated.push(".ciagent/REQUIREMENTS.md", ".ciagent/ROADMAP.md");
+          decisionsMade += savedCount;
+        }
+
+        this.pipelineState!.ideate_completed = true;
+        this.log(`Ideation stage complete: ${trimmedIdeas.length} ideas generated`);
+        break;
+      }
+
       case "plan":
         this.log("Planning phase execution...");
 

src/types/pipeline.test.ts

@@ -62,4 +62,14 @@ describe("createInitialPipelineState", () => {
     expect(state.started_at).toBeTruthy();
     expect(state.last_updated).toBeTruthy();
   });
+});
+
+describe("STAGE_ORDER ideate position", () => {
+  it("places ideate between research and plan", () => {
+    const ideateIdx = STAGE_ORDER.indexOf("ideate");
+    const researchIdx = STAGE_ORDER.indexOf("research");
+    const planIdx = STAGE_ORDER.indexOf("plan");
+    expect(ideateIdx).toBeGreaterThan(researchIdx);
+    expect(ideateIdx).toBeLessThan(planIdx);
+  });
 });