Pipeline Restructuring Plan

Goal

Split agent/pipeline.go (~1400 lines) into multiple logical files, organizing code by responsibility.

Final File Structure

pkg/agent/
├── pipeline.go           # Pipeline struct + NewPipeline (~39 lines)
├── pipeline_setup.go   # SetupTurn method (~115 lines)
├── pipeline_llm.go     # CallLLM method (~519 lines)
├── pipeline_execute.go  # ExecuteTools method (~693 lines)
└── pipeline_finalize.go # Finalize method (~78 lines)

Actual Line Counts

File	Lines
`pipeline.go`	39
`pipeline_setup.go`	115
`pipeline_llm.go`	519
`pipeline_execute.go`	693
`pipeline_finalize.go`	78
Total	1444

Responsibility Matrix

File	Method	Responsibility
`pipeline.go`	`Pipeline` struct, `NewPipeline()`	Pipeline dependency container
`pipeline_setup.go`	`SetupTurn()`	Turn initialization: history assembly, message building, candidate selection
`pipeline_llm.go`	`CallLLM()`	LLM call: PreLLM hooks, fallback, retry, AfterLLM hooks
`pipeline_execute.go`	`ExecuteTools()`	Tool execution: BeforeTool/ApproveTool/AfterTool hooks, media sending, steering handling
`pipeline_finalize.go`	`Finalize()`	Turn finalization: session save, compression, status setting

Relationship Between Pipeline and Turn Coordinator

AgentLoop (agent.go)
    │
    ├── runAgentLoop() ──────────────────┐
    │                                    │
    │    ┌───────────────────────────────▼───────────────────────────────┐
    │    │                    Turn Coordinator (turn_coord.go)           │
    │    │                                                           │
    │    │   runTurn() {                                             │
    │    │       exec = pipeline.SetupTurn()                          │
    │    │       loop {                                              │
    │    │           ctrl = pipeline.CallLLM()  ──► Pipeline (pipeline_*.go) │
    │    │           if ctrl == ToolLoop {                            │
    │    │               toolCtrl = pipeline.ExecuteTools()             │
    │    │           }                                                │
    │    │       }                                                    │
    │    │       return pipeline.Finalize()                            │
    │    │   }                                                         │
    │    └─────────────────────────────────────────────────────────────┘
    │
    └── Publish response (agent_outbound.go)

Verification Results

✅ go build ./pkg/agent/... - Pass
✅ go vet ./pkg/agent/... - No warnings
✅ go test ./pkg/agent/... -skip "TestSeahorse|TestGlobalSkillFileContentChange" - Pass