Merge pull request #696 from tonybaloney/cookbook/ralph-loop-recipe

Add RALPH-loop recipes to Copilot SDK cookbook
2026-02-24 04:15:14 +00:00 · 2026-02-12 10:23:19 +11:00
parent 3efeef350e 717c0121bc
commit ef3c1e5ad6
10 changed files with 1405 additions and 2 deletions
--- a/cookbook/copilot-sdk/go/ralph-loop.md
+++ b/cookbook/copilot-sdk/go/ralph-loop.md
@@ -0,0 +1,296 @@
+# Ralph Loop: Autonomous AI Task Loops
+
+Build autonomous coding loops where an AI agent picks tasks, implements them, validates against backpressure (tests, builds), commits, and repeats — each iteration in a fresh context window.
+
+> **Runnable example:** [recipe/ralph-loop.go](recipe/ralph-loop.go)
+>
+> ```bash
+> cd go
+> go run recipe/ralph-loop.go
+> ```
+
+## What is a Ralph Loop?
+
+A [Ralph loop](https://ghuntley.com/ralph/) is an autonomous development workflow where an AI agent iterates through tasks in isolated context windows. The key insight: **state lives on disk, not in the model's context**. Each iteration starts fresh, reads the current state from files, does one task, writes results back to disk, and exits.
+
+```
+┌─────────────────────────────────────────────────┐
+│                   loop.sh                       │
+│  while true:                                    │
+│    ┌─────────────────────────────────────────┐  │
+│    │  Fresh session (isolated context)       │  │
+│    │                                         │  │
+│    │  1. Read PROMPT.md + AGENTS.md          │  │
+│    │  2. Study specs/* and code              │  │
+│    │  3. Pick next task from plan            │  │
+│    │  4. Implement + run tests               │  │
+│    │  5. Update plan, commit, exit           │  │
+│    └─────────────────────────────────────────┘  │
+│    ↻ next iteration (fresh context)             │
+└─────────────────────────────────────────────────┘
+```
+
+**Core principles:**
+
+- **Fresh context per iteration**: Each loop creates a new session — no context accumulation, always in the "smart zone"
+- **Disk as shared state**: `IMPLEMENTATION_PLAN.md` persists between iterations and acts as the coordination mechanism
+- **Backpressure steers quality**: Tests, builds, and lints reject bad work — the agent must fix issues before committing
+- **Two modes**: PLANNING (gap analysis → generate plan) and BUILDING (implement from plan)
+
+## Simple Version
+
+The minimal Ralph loop — the SDK equivalent of `while :; do cat PROMPT.md | copilot ; done`:
+
+```go
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"os"
+
+	copilot "github.com/github/copilot-sdk/go"
+)
+
+func ralphLoop(ctx context.Context, promptFile string, maxIterations int) error {
+	client := copilot.NewClient(nil)
+	if err := client.Start(ctx); err != nil {
+		return err
+	}
+	defer client.Stop()
+
+	prompt, err := os.ReadFile(promptFile)
+	if err != nil {
+		return err
+	}
+
+	for i := 1; i <= maxIterations; i++ {
+		fmt.Printf("\n=== Iteration %d/%d ===\n", i, maxIterations)
+
+		// Fresh session each iteration — context isolation is the point
+		session, err := client.CreateSession(ctx, &copilot.SessionConfig{
+			Model: "gpt-5.1-codex-mini",
+		})
+		if err != nil {
+			return err
+		}
+
+		_, err = session.SendAndWait(ctx, copilot.MessageOptions{
+			Prompt: string(prompt),
+		})
+		session.Destroy()
+		if err != nil {
+			return err
+		}
+
+		fmt.Printf("Iteration %d complete.\n", i)
+	}
+	return nil
+}
+
+func main() {
+	if err := ralphLoop(context.Background(), "PROMPT.md", 20); err != nil {
+		log.Fatal(err)
+	}
+}
+```
+
+This is all you need to get started. The prompt file tells the agent what to do; the agent reads project files, does work, commits, and exits. The loop restarts with a clean slate.
+
+## Ideal Version
+
+The full Ralph pattern with planning and building modes, matching the [Ralph Playbook](https://github.com/ClaytonFarr/ralph-playbook) architecture:
+
+```go
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+
+	copilot "github.com/github/copilot-sdk/go"
+)
+
+func ralphLoop(ctx context.Context, mode string, maxIterations int) error {
+	promptFile := "PROMPT_build.md"
+	if mode == "plan" {
+		promptFile = "PROMPT_plan.md"
+	}
+
+	client := copilot.NewClient(nil)
+	if err := client.Start(ctx); err != nil {
+		return err
+	}
+	defer client.Stop()
+
+	cwd, _ := os.Getwd()
+
+	fmt.Println(strings.Repeat("━", 40))
+	fmt.Printf("Mode:   %s\n", mode)
+	fmt.Printf("Prompt: %s\n", promptFile)
+	fmt.Printf("Max:    %d iterations\n", maxIterations)
+	fmt.Println(strings.Repeat("━", 40))
+
+	prompt, err := os.ReadFile(promptFile)
+	if err != nil {
+		return err
+	}
+
+	for i := 1; i <= maxIterations; i++ {
+		fmt.Printf("\n=== Iteration %d/%d ===\n", i, maxIterations)
+
+		session, err := client.CreateSession(ctx, &copilot.SessionConfig{
+			Model:            "gpt-5.1-codex-mini",
+			WorkingDirectory: cwd,
+			OnPermissionRequest: func(_ copilot.PermissionRequest, _ map[string]string) copilot.PermissionRequestResult {
+				return copilot.PermissionRequestResult{Kind: "approved"}
+			},
+		})
+		if err != nil {
+			return err
+		}
+
+		// Log tool usage for visibility
+		session.On(func(event copilot.Event) {
+			if toolExecution, ok := event.(copilot.ToolExecutionStartEvent); ok {
+				fmt.Printf("  ⚙ %s\n", toolExecution.Data.ToolName)
+			}
+		})
+
+		_, err = session.SendAndWait(ctx, copilot.MessageOptions{
+			Prompt: string(prompt),
+		})
+		session.Destroy()
+		if err != nil {
+			return err
+		}
+
+		fmt.Printf("\nIteration %d complete.\n", i)
+	}
+
+	fmt.Printf("\nReached max iterations: %d\n", maxIterations)
+	return nil
+}
+
+func main() {
+	mode := "build"
+	maxIterations := 50
+
+	for _, arg := range os.Args[1:] {
+		if arg == "plan" {
+			mode = "plan"
+		} else if n, err := strconv.Atoi(arg); err == nil {
+			maxIterations = n
+		}
+	}
+
+	if err := ralphLoop(context.Background(), mode, maxIterations); err != nil {
+		log.Fatal(err)
+	}
+}
+```
+
+### Required Project Files
+
+The ideal version expects this file structure in your project:
+
+```
+project-root/
+├── PROMPT_plan.md              # Planning mode instructions
+├── PROMPT_build.md             # Building mode instructions
+├── AGENTS.md                   # Operational guide (build/test commands)
+├── IMPLEMENTATION_PLAN.md      # Task list (generated by planning mode)
+├── specs/                      # Requirement specs (one per topic)
+│   ├── auth.md
+│   └── data-pipeline.md
+└── src/                        # Your source code
+```
+
+### Example `PROMPT_plan.md`
+
+```markdown
+0a. Study `specs/*` to learn the application specifications.
+0b. Study IMPLEMENTATION_PLAN.md (if present) to understand the plan so far.
+0c. Study `src/` to understand existing code and shared utilities.
+
+1. Compare specs against code (gap analysis). Create or update
+   IMPLEMENTATION_PLAN.md as a prioritized bullet-point list of tasks
+   yet to be implemented. Do NOT implement anything.
+
+IMPORTANT: Do NOT assume functionality is missing — search the
+codebase first to confirm. Prefer updating existing utilities over
+creating ad-hoc copies.
+```
+
+### Example `PROMPT_build.md`
+
+```markdown
+0a. Study `specs/*` to learn the application specifications.
+0b. Study IMPLEMENTATION_PLAN.md.
+0c. Study `src/` for reference.
+
+1. Choose the most important item from IMPLEMENTATION_PLAN.md. Before
+   making changes, search the codebase (don't assume not implemented).
+2. After implementing, run the tests. If functionality is missing, add it.
+3. When you discover issues, update IMPLEMENTATION_PLAN.md immediately.
+4. When tests pass, update IMPLEMENTATION_PLAN.md, then `git add -A`
+   then `git commit` with a descriptive message.
+
+5. When authoring documentation, capture the why.
+6. Implement completely. No placeholders or stubs.
+7. Keep IMPLEMENTATION_PLAN.md current — future iterations depend on it.
+```
+
+### Example `AGENTS.md`
+
+Keep this brief (~60 lines). It's loaded every iteration, so bloat wastes context.
+
+```markdown
+## Build & Run
+
+go build ./...
+
+## Validation
+
+- Tests: `go test ./...`
+- Vet: `go vet ./...`
+```
+
+## Best Practices
+
+1. **Fresh context per iteration**: Never accumulate context across iterations — that's the whole point
+2. **Disk is your database**: `IMPLEMENTATION_PLAN.md` is shared state between isolated sessions
+3. **Backpressure is essential**: Tests, builds, lints in `AGENTS.md` — the agent must pass them before committing
+4. **Start with PLANNING mode**: Generate the plan first, then switch to BUILDING
+5. **Observe and tune**: Watch early iterations, add guardrails to prompts when the agent fails in specific ways
+6. **The plan is disposable**: If the agent goes off track, delete `IMPLEMENTATION_PLAN.md` and re-plan
+7. **Keep `AGENTS.md` brief**: It's loaded every iteration — operational info only, no progress notes
+8. **Use a sandbox**: The agent runs autonomously with full tool access — isolate it
+9. **Set `WorkingDirectory`**: Pin the session to your project root so tool operations resolve paths correctly
+10. **Auto-approve permissions**: Use `OnPermissionRequest` to allow tool calls without interrupting the loop
+
+## When to Use a Ralph Loop
+
+**Good for:**
+
+- Implementing features from specs with test-driven validation
+- Large refactors broken into many small tasks
+- Unattended, long-running development with clear requirements
+- Any work where backpressure (tests/builds) can verify correctness
+
+**Not good for:**
+
+- Tasks requiring human judgment mid-loop
+- One-shot operations that don't benefit from iteration
+- Vague requirements without testable acceptance criteria
+- Exploratory prototyping where direction isn't clear
+
+## See Also
+
+- [Error Handling](error-handling.md) — timeout patterns and graceful shutdown for long-running sessions
+- [Persisting Sessions](persisting-sessions.md) — save and resume sessions across restarts
--- a/cookbook/copilot-sdk/go/recipe/ralph-loop.go
+++ b/cookbook/copilot-sdk/go/recipe/ralph-loop.go
@@ -0,0 +1,111 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"os"
+	"strconv"
+	"strings"
+
+	copilot "github.com/github/copilot-sdk/go"
+)
+
+// Ralph loop: autonomous AI task loop with fresh context per iteration.
+//
+// Two modes:
+//   - "plan": reads PROMPT_plan.md, generates/updates IMPLEMENTATION_PLAN.md
+//   - "build": reads PROMPT_build.md, implements tasks, runs tests, commits
+//
+// Each iteration creates a fresh session so the agent always operates in
+// the "smart zone" of its context window. State is shared between
+// iterations via files on disk (IMPLEMENTATION_PLAN.md, AGENTS.md, specs/*).
+//
+// Usage:
+//   go run ralph-loop.go              # build mode, 50 iterations
+//   go run ralph-loop.go plan         # planning mode
+//   go run ralph-loop.go 20           # build mode, 20 iterations
+//   go run ralph-loop.go plan 5       # planning mode, 5 iterations
+
+func ralphLoop(ctx context.Context, mode string, maxIterations int) error {
+	promptFile := "PROMPT_build.md"
+	if mode == "plan" {
+		promptFile = "PROMPT_plan.md"
+	}
+
+	client := copilot.NewClient(nil)
+	if err := client.Start(ctx); err != nil {
+		return fmt.Errorf("failed to start client: %w", err)
+	}
+	defer client.Stop()
+
+	cwd, err := os.Getwd()
+	if err != nil {
+		return fmt.Errorf("failed to get working directory: %w", err)
+	}
+
+	fmt.Println(strings.Repeat("━", 40))
+	fmt.Printf("Mode:   %s\n", mode)
+	fmt.Printf("Prompt: %s\n", promptFile)
+	fmt.Printf("Max:    %d iterations\n", maxIterations)
+	fmt.Println(strings.Repeat("━", 40))
+
+	prompt, err := os.ReadFile(promptFile)
+	if err != nil {
+		return fmt.Errorf("failed to read %s: %w", promptFile, err)
+	}
+
+	for i := 1; i <= maxIterations; i++ {
+		fmt.Printf("\n=== Iteration %d/%d ===\n", i, maxIterations)
+
+		session, err := client.CreateSession(ctx, &copilot.SessionConfig{
+			Model:            "gpt-5.1-codex-mini",
+			WorkingDirectory: cwd,
+			OnPermissionRequest: func(_ copilot.PermissionRequest, _ map[string]string) copilot.PermissionRequestResult {
+				return copilot.PermissionRequestResult{Kind: "approved"}
+			},
+		})
+		if err != nil {
+			return fmt.Errorf("failed to create session: %w", err)
+		}
+
+		// Log tool usage for visibility
+		session.On(func(event copilot.Event) {
+			if toolExecution, ok := event.(copilot.ToolExecutionStartEvent); ok {
+				fmt.Printf("  ⚙ %s\n", toolExecution.Data.ToolName)
+			}
+		})
+
+		_, err = session.SendAndWait(ctx, copilot.MessageOptions{
+			Prompt: string(prompt),
+		})
+		if destroyErr := session.Destroy(); destroyErr != nil {
+			log.Printf("failed to destroy session on iteration %d: %v", i, destroyErr)
+		}
+		if err != nil {
+			return fmt.Errorf("send failed on iteration %d: %w", i, err)
+		}
+
+		fmt.Printf("\nIteration %d complete.\n", i)
+	}
+
+	fmt.Printf("\nReached max iterations: %d\n", maxIterations)
+	return nil
+}
+
+func main() {
+	mode := "build"
+	maxIterations := 50
+
+	for _, arg := range os.Args[1:] {
+		if arg == "plan" {
+			mode = "plan"
+		} else if n, err := strconv.Atoi(arg); err == nil {
+			maxIterations = n
+		}
+	}
+
+	if err := ralphLoop(context.Background(), mode, maxIterations); err != nil {
+		log.Fatal(err)
+	}
+}