Add generate_image tool and show Codex images inline

internal/agents/codex.go

@@ -3,6 +3,7 @@ package agents
 import (
 	"context"
 	"encoding/json"
+	"fmt"
 	"log/slog"
 	"os"
 	"strings"
@@ -143,6 +144,16 @@ func (m *Manager) codexItemCompleted(ctx context.Context, l *live, s *codex.Sess
 			return nil
 		}
 		return m.emit(ctx, l, agentActor, "agent.thinking", map[string]any{"text": text})
+
+	case codex.ThreadItemTypeImageGeneration:
+		if item.SavedPath == "" || l.reviewID != "" || l.owner != "" {
+			return nil
+		}
+		path, err := copyToMedia(MediaDir(l.dir), string(item.SavedPath))
+		if err != nil {
+			return err
+		}
+		return m.emit(ctx, l, agentActor, "agent.message", map[string]any{"text": fmt.Sprintf("![%s](<%s>)", imageAlt(item.RevisedPrompt), path)})
 	}
 
 	if !codexToolItems[item.Type] {
@@ -188,6 +199,17 @@ func (m *Manager) codexItemCompleted(ctx context.Context, l *live, s *codex.Sess
 	return nil
 }
 
+func imageAlt(prompt string) string {
+	alt := strings.NewReplacer("[", "", "]", "", "\n", " ").Replace(strings.TrimSpace(prompt))
+	if r := []rune(alt); len(r) > 120 {
+		alt = string(r[:120]) + "…"
+	}
+	if alt == "" {
+		return "generated image"
+	}
+	return alt
+}
+
 func codexToolResult(item codex.ThreadItem) (string, bool) {
 	status := codexStatus(item)
 	switch item.Type {

internal/agents/imagegen.go

@@ -0,0 +1,125 @@
+package agents
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"g.fc.run/ai/byre/internal/codex"
+	"g.fc.run/ai/byre/internal/mcp"
+)
+
+const imageGenGuidance = "You make images for another agent. Call your image_gen tool exactly once with the prompt you are given, unchanged, then reply with only the word done."
+
+func (m *Manager) generateImageTool(l *live) mcp.Tool {
+	return mcp.Tool{
+		Name: "generate_image",
+		Description: "Generate an image (a photo, illustration, texture, sprite, mockup) with OpenAI's image model through byre's Codex sign-in, saved as a PNG in the task's media folder. " +
+			"The reply gives its path: show it inline by embedding it in your final message as a Markdown image, ![what it shows](<path>), or copy it into the worktree when the project uses it. " +
+			"Use it whenever the human asks for a picture, rather than drawing one in SVG or HTML. It takes a minute or two.",
+		InputSchema: json.RawMessage(`{
+			"type": "object",
+			"properties": {
+				"prompt": {"type": "string", "description": "What to draw: subject, style, composition, lighting, and any exact text."}
+			},
+			"required": ["prompt"]
+		}`),
+		Handler: func(ctx context.Context, raw json.RawMessage) (string, error) {
+			return m.generateImage(ctx, l, raw)
+		},
+	}
+}
+
+func (m *Manager) generateImage(ctx context.Context, l *live, raw json.RawMessage) (string, error) {
+	args := struct {
+		Prompt string `json:"prompt"`
+	}{}
+	err := json.Unmarshal(raw, &args)
+	if err != nil {
+		return "", fmt.Errorf("malformed generate_image call: %w", err)
+	}
+	if strings.TrimSpace(args.Prompt) == "" {
+		return "", fmt.Errorf("generate_image needs a prompt")
+	}
+
+	media := MediaDir(l.dir)
+	err = os.MkdirAll(m.codexHome, 0o700)
+	if err != nil {
+		return "", err
+	}
+	s, err := codex.Start(ctx, codex.Options{
+		Cwd:      media,
+		Env:      []string{"CODEX_HOME=" + m.codexHome},
+		Guidance: imageGenGuidance,
+	})
+	if err != nil {
+		return "", fmt.Errorf("start codex: %w", err)
+	}
+	defer s.Close()
+
+	_, err = s.Send(ctx, args.Prompt)
+	if err != nil {
+		return "", fmt.Errorf("start codex turn: %w", err)
+	}
+
+	saved := ""
+	for {
+		select {
+		case <-ctx.Done():
+			s.Kill()
+			return "", fmt.Errorf("no image after %s", mcp.Timeout(ctx))
+		case ev, ok := <-s.Events():
+			if !ok {
+				return "", fmt.Errorf("codex exited before the image was made")
+			}
+			switch ev.Method {
+			case codex.MethodItemCompleted:
+				n := codex.ItemCompletedNotification{}
+				err := json.Unmarshal(ev.Params, &n)
+				if err != nil {
+					return "", err
+				}
+				if n.Item.Type != codex.ThreadItemTypeImageGeneration {
+					continue
+				}
+				if n.Item.Failure != nil {
+					return "", fmt.Errorf("image generation failed: %s (limit %s)", n.Item.Failure.Type, n.Item.Failure.LimitID)
+				}
+				saved = string(n.Item.SavedPath)
+			case codex.MethodTurnCompleted:
+				n := codex.TurnCompletedNotification{}
+				err := json.Unmarshal(ev.Params, &n)
+				if err != nil {
+					return "", err
+				}
+				if n.Turn.Error != nil {
+					return "", fmt.Errorf("codex: %s", n.Turn.Error.Message)
+				}
+				if saved == "" {
+					return "", fmt.Errorf("codex finished without making an image")
+				}
+				path, err := copyToMedia(media, saved)
+				if err != nil {
+					return "", err
+				}
+				return fmt.Sprintf("Saved %s", path), nil
+			}
+		}
+	}
+}
+
+func copyToMedia(media, src string) (string, error) {
+	data, err := os.ReadFile(src)
+	if err != nil {
+		return "", err
+	}
+	err = os.MkdirAll(media, 0o755)
+	if err != nil {
+		return "", err
+	}
+	dest := filepath.Join(media, filepath.Base(src))
+	return dest, os.WriteFile(dest, data, 0o644)
+}

internal/agents/kb/images.md

@@ -0,0 +1,15 @@
+How agents make real images (photos, illustrations) with generate_image, and how they show inline in the transcript.
+
+# Generating images
+
+`generate_image` makes a raster image from a prompt and saves it as a PNG in the task's media folder (`<worktree>-media/`, outside the worktree, deleted when the task closes). Embed the path it returns in your final message as `![what it shows](<path>)` and the human sees it inline in the transcript; copy it into the worktree when the project itself uses it.
+
+It runs one Codex turn on the Mac byre runs on, under byre's Codex home, and calls Codex's built-in image tool (OpenAI's image model), so:
+
+- It needs Codex signed in there (the `setup` article covers it); until then it fails with `401 Unauthorized`.
+- Each image counts against the ChatGPT plan's Codex usage, whichever vendor the calling agent runs on.
+- One call takes a minute or two; give it a timeout of at least 3 minutes.
+
+Codex agents (gpt-* models) also have the image tool built in. An image one makes is copied into the media folder and shown inline in the transcript by byre, with no Markdown needed.
+
+Write the prompt as a short spec: subject, style or medium, composition, lighting, and any exact text in quotes. For a change, generate again with the one change stated; it can't edit an earlier image in place.

internal/agents/manager.go

@@ -885,6 +885,7 @@ func (m *Manager) startLive(ctx context.Context, sess api.AgentSession, task api
 			return nil, err
 		}
 		g += screenshotGuidance
+		tools = append(tools, m.generateImageTool(l))
 		hands, err := m.handsMCP(sess.Id, media)
 		if err != nil {
 			return nil, err