fix: 7 bugs from discussion #149 smoke walk (envelope, spawn, CDC, observer)

backend/internal/adapters/agent/agy/agy.go

@@ -5,6 +5,7 @@ package agy
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -182,7 +183,7 @@ func ResolveAgyBinary(ctx context.Context) (string, error) {
 			}
 		}
 
-		return "agy", nil
+		return "", fmt.Errorf("agy: %w", ports.ErrAgentBinaryNotFound)
 	}
 
 	if path, err := exec.LookPath("agy"); err == nil && path != "" {
@@ -210,7 +211,7 @@ func ResolveAgyBinary(ctx context.Context) (string, error) {
 		}
 	}
 
-	return "agy", nil
+	return "", fmt.Errorf("agy: %w", ports.ErrAgentBinaryNotFound)
 }
 
 func (p *Plugin) agyBinary(ctx context.Context) (string, error) {

backend/internal/adapters/agent/aider/aider.go

@@ -10,6 +10,7 @@ package aider
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -173,7 +174,7 @@ func ResolveAiderBinary(ctx context.Context) (string, error) {
 				return "", err
 			}
 		}
-		return "aider", nil
+		return "", fmt.Errorf("aider: %w", ports.ErrAgentBinaryNotFound)
 	}
 
 	if path, err := exec.LookPath("aider"); err == nil && path != "" {
@@ -197,7 +198,7 @@ func ResolveAiderBinary(ctx context.Context) (string, error) {
 		}
 	}
 
-	return "aider", nil
+	return "", fmt.Errorf("aider: %w", ports.ErrAgentBinaryNotFound)
 }
 
 func (p *Plugin) aiderBinary(ctx context.Context) (string, error) {

backend/internal/adapters/agent/aider/aider_test.go

@@ -281,11 +281,17 @@ func TestContextCancellation(t *testing.T) {
 }
 
 func TestResolveAiderBinaryFallback(t *testing.T) {
+	// When the binary is not on PATH or any well-known location, the resolver
+	// MUST surface ports.ErrAgentBinaryNotFound rather than a silent string
+	// fallback that lets a missing CLI launch into an empty zellij pane.
 	bin, err := ResolveAiderBinary(context.Background())
 	if err != nil {
-		t.Fatalf("err: %v", err)
+		if !errors.Is(err, ports.ErrAgentBinaryNotFound) {
+			t.Fatalf("err = %v, want ports.ErrAgentBinaryNotFound", err)
+		}
+		return
 	}
 	if bin == "" {
-		t.Fatal("ResolveAiderBinary returned empty string")
+		t.Fatal("ResolveAiderBinary returned empty string with no error")
 	}
 }

backend/internal/adapters/agent/amp/amp.go

@@ -8,6 +8,7 @@ package amp
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -176,7 +177,7 @@ func ResolveAmpBinary(ctx context.Context) (string, error) {
 				return "", err
 			}
 		}
-		return "amp", nil
+		return "", fmt.Errorf("amp: %w", ports.ErrAgentBinaryNotFound)
 	}
 
 	if path, err := exec.LookPath("amp"); err == nil && path != "" {
@@ -203,7 +204,7 @@ func ResolveAmpBinary(ctx context.Context) (string, error) {
 		}
 	}
 
-	return "amp", nil
+	return "", fmt.Errorf("amp: %w", ports.ErrAgentBinaryNotFound)
 }
 
 func (p *Plugin) ampBinary(ctx context.Context) (string, error) {

backend/internal/adapters/agent/auggie/auggie.go

@@ -38,6 +38,7 @@ package auggie
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -201,7 +202,7 @@ func ResolveAuggieBinary(ctx context.Context) (string, error) {
 				return "", err
 			}
 		}
-		return "auggie", nil
+		return "", fmt.Errorf("auggie: %w", ports.ErrAgentBinaryNotFound)
 	}
 
 	if path, err := exec.LookPath("auggie"); err == nil && path != "" {
@@ -229,7 +230,7 @@ func ResolveAuggieBinary(ctx context.Context) (string, error) {
 		}
 	}
 
-	return "auggie", nil
+	return "", fmt.Errorf("auggie: %w", ports.ErrAgentBinaryNotFound)
 }
 
 func (p *Plugin) auggieBinary(ctx context.Context) (string, error) {

backend/internal/adapters/agent/auggie/auggie_test.go

@@ -184,14 +184,18 @@ func TestSessionInfoNoOp(t *testing.T) {
 }
 
 func TestResolveAuggieBinaryFallback(t *testing.T) {
-	// With a cancelled context the resolver returns the context error rather than
-	// a binary path; with a live context it always yields a non-empty path.
+	// When the binary is not on PATH or any well-known location, the resolver
+	// MUST surface ports.ErrAgentBinaryNotFound rather than a silent string
+	// fallback that lets a missing CLI launch into an empty zellij pane.
 	bin, err := ResolveAuggieBinary(context.Background())
 	if err != nil {
-		t.Fatalf("ResolveAuggieBinary err = %v", err)
+		if !errors.Is(err, ports.ErrAgentBinaryNotFound) {
+			t.Fatalf("err = %v, want ports.ErrAgentBinaryNotFound", err)
+		}
+		return
 	}
 	if bin == "" {
-		t.Fatal("ResolveAuggieBinary returned empty path")
+		t.Fatal("ResolveAuggieBinary returned empty path with no error")
 	}
 }
 

backend/internal/adapters/agent/autohand/autohand.go

@@ -12,6 +12,7 @@ package autohand
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -225,7 +226,7 @@ func ResolveAutohandBinary(ctx context.Context) (string, error) {
 			}
 		}
 
-		return "autohand", nil
+		return "", fmt.Errorf("autohand: %w", ports.ErrAgentBinaryNotFound)
 	}
 
 	if path, err := exec.LookPath("autohand"); err == nil && path != "" {
@@ -252,7 +253,7 @@ func ResolveAutohandBinary(ctx context.Context) (string, error) {
 		}
 	}
 
-	return "autohand", nil
+	return "", fmt.Errorf("autohand: %w", ports.ErrAgentBinaryNotFound)
 }
 
 func (p *Plugin) autohandBinary(ctx context.Context) (string, error) {

backend/internal/adapters/agent/claudecode/claudecode.go

@@ -306,7 +306,7 @@ func ResolveClaudeBinary(ctx context.Context) (string, error) {
 				return candidate, nil
 			}
 		}
-		return "claude", nil
+		return "", fmt.Errorf("claude: %w", ports.ErrAgentBinaryNotFound)
 	}
 
 	if path, err := exec.LookPath("claude"); err == nil && path != "" {
@@ -333,7 +333,7 @@ func ResolveClaudeBinary(ctx context.Context) (string, error) {
 		}
 	}
 
-	return "claude", nil
+	return "", fmt.Errorf("claude: %w", ports.ErrAgentBinaryNotFound)
 }
 
 func (p *Plugin) claudeBinary(ctx context.Context) (string, error) {

backend/internal/adapters/agent/cline/cline.go

@@ -14,6 +14,7 @@ package cline
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -178,7 +179,7 @@ func ResolveClineBinary(ctx context.Context) (string, error) {
 			}
 		}
 
-		return "cline", nil
+		return "", fmt.Errorf("cline: %w", ports.ErrAgentBinaryNotFound)
 	}
 
 	if path, err := exec.LookPath("cline"); err == nil && path != "" {
@@ -206,7 +207,7 @@ func ResolveClineBinary(ctx context.Context) (string, error) {
 		}
 	}
 
-	return "cline", nil
+	return "", fmt.Errorf("cline: %w", ports.ErrAgentBinaryNotFound)
 }
 
 func (p *Plugin) clineBinary(ctx context.Context) (string, error) {

backend/internal/adapters/agent/codex/codex.go

@@ -8,6 +8,7 @@ package codex
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -175,7 +176,7 @@ func ResolveCodexBinary(ctx context.Context) (string, error) {
 			}
 		}
 
-		return "codex", nil
+		return "", fmt.Errorf("codex: %w", ports.ErrAgentBinaryNotFound)
 	}
 
 	if path, err := exec.LookPath("codex"); err == nil && path != "" {
@@ -202,7 +203,7 @@ func ResolveCodexBinary(ctx context.Context) (string, error) {
 		}
 	}
 
-	return "codex", nil
+	return "", fmt.Errorf("codex: %w", ports.ErrAgentBinaryNotFound)
 }
 
 func (p *Plugin) codexBinary(ctx context.Context) (string, error) {

backend/internal/adapters/agent/continueagent/continueagent.go

@@ -22,6 +22,7 @@ package continueagent
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -197,7 +198,7 @@ func ResolveContinueBinary(ctx context.Context) (string, error) {
 				return "", err
 			}
 		}
-		return "cn", nil
+		return "", fmt.Errorf("cn: %w", ports.ErrAgentBinaryNotFound)
 	}
 
 	if path, err := exec.LookPath("cn"); err == nil && path != "" {
@@ -225,7 +226,7 @@ func ResolveContinueBinary(ctx context.Context) (string, error) {
 		}
 	}
 
-	return "cn", nil
+	return "", fmt.Errorf("cn: %w", ports.ErrAgentBinaryNotFound)
 }
 
 func (p *Plugin) continueBinary(ctx context.Context) (string, error) {

backend/internal/adapters/agent/copilot/copilot.go

@@ -19,6 +19,7 @@ package copilot
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -189,7 +190,7 @@ func ResolveCopilotBinary(ctx context.Context) (string, error) {
 			}
 		}
 
-		return "copilot", nil
+		return "", fmt.Errorf("copilot: %w", ports.ErrAgentBinaryNotFound)
 	}
 
 	if path, err := exec.LookPath("copilot"); err == nil && path != "" {
@@ -217,7 +218,7 @@ func ResolveCopilotBinary(ctx context.Context) (string, error) {
 		}
 	}
 
-	return "copilot", nil
+	return "", fmt.Errorf("copilot: %w", ports.ErrAgentBinaryNotFound)
 }
 
 func (p *Plugin) copilotBinary(ctx context.Context) (string, error) {

backend/internal/adapters/agent/crush/crush.go

@@ -8,6 +8,7 @@ package crush
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -191,7 +192,7 @@ func ResolveCrushBinary(ctx context.Context) (string, error) {
 			}
 		}
 
-		return "crush", nil
+		return "", fmt.Errorf("crush: %w", ports.ErrAgentBinaryNotFound)
 	}
 
 	if path, err := exec.LookPath("crush"); err == nil && path != "" {
@@ -218,7 +219,7 @@ func ResolveCrushBinary(ctx context.Context) (string, error) {
 		}
 	}
 
-	return "crush", nil
+	return "", fmt.Errorf("crush: %w", ports.ErrAgentBinaryNotFound)
 }
 
 func (p *Plugin) crushBinary(ctx context.Context) (string, error) {

backend/internal/adapters/agent/cursor/cursor.go

@@ -9,6 +9,7 @@ package cursor
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -165,7 +166,7 @@ func ResolveCursorBinary(ctx context.Context) (string, error) {
 				return "", err
 			}
 		}
-		return "cursor-agent", nil
+		return "", fmt.Errorf("cursor: %w", ports.ErrAgentBinaryNotFound)
 	}
 
 	if path, err := exec.LookPath("cursor-agent"); err == nil && path != "" {
@@ -190,7 +191,7 @@ func ResolveCursorBinary(ctx context.Context) (string, error) {
 		}
 	}
 
-	return "cursor-agent", nil
+	return "", fmt.Errorf("cursor: %w", ports.ErrAgentBinaryNotFound)
 }
 
 func (p *Plugin) cursorBinary(ctx context.Context) (string, error) {

backend/internal/adapters/agent/devin/devin.go

@@ -24,6 +24,7 @@ package devin
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"os/exec"
 	"path/filepath"
@@ -200,7 +201,7 @@ func ResolveDevinBinary(ctx context.Context) (string, error) {
 				return "", err
 			}
 		}
-		return "devin", nil
+		return "", fmt.Errorf("devin: %w", ports.ErrAgentBinaryNotFound)
 	}
 
 	if path, err := exec.LookPath("devin"); err == nil && path != "" {
@@ -227,7 +228,7 @@ func ResolveDevinBinary(ctx context.Context) (string, error) {
 		}
 	}
 
-	return "devin", nil
+	return "", fmt.Errorf("devin: %w", ports.ErrAgentBinaryNotFound)
 }
 
 func (p *Plugin) devinBinary(ctx context.Context) (string, error) {