feat(daemon): add BD_SOCKET env var for test isolation (#914)

Add BD_SOCKET environment variable support to override daemon socket path,
enabling parallel test isolation via t.TempDir() + t.Setenv().

Changes:
- getSocketPath() checks BD_SOCKET first, falls back to dbPath-derived path
- getSocketPathForPID() checks BD_SOCKET first (for consistency)
- Add daemon_socket_test.go with isolation pattern examples

This is a minimal tracer bullet to validate the approach before
expanding to full test isolation infrastructure.

Backward compatible: default behavior unchanged without env var set.

cmd/bd/daemon_autostart.go

@@ -455,9 +455,14 @@ func recordDaemonStartFailure() {
 	// No cap needed - backoff is capped at 120s in canRetryDaemonStart
 }
 
-// getSocketPath returns the daemon socket path based on the database location
+// getSocketPath returns the daemon socket path based on the database location.
+// If BD_SOCKET env var is set, uses that value instead (enables test isolation).
 // Returns local socket path (.beads/bd.sock relative to database)
 func getSocketPath() string {
+	// Check environment variable first (enables test isolation)
+	if socketPath := os.Getenv("BD_SOCKET"); socketPath != "" {
+		return socketPath
+	}
 	return filepath.Join(filepath.Dir(dbPath), "bd.sock")
 }
 

cmd/bd/daemon_config.go

@@ -58,8 +58,13 @@ func getEnvBool(key string, defaultValue bool) bool {
 	return defaultValue
 }
 
-// getSocketPathForPID determines the socket path for a given PID file
+// getSocketPathForPID determines the socket path for a given PID file.
+// If BD_SOCKET env var is set, uses that value instead.
 func getSocketPathForPID(pidFile string) string {
+	// Check environment variable first (enables test isolation)
+	if socketPath := os.Getenv("BD_SOCKET"); socketPath != "" {
+		return socketPath
+	}
 	// Socket is in same directory as PID file
 	return filepath.Join(filepath.Dir(pidFile), "bd.sock")
 }

cmd/bd/daemon_socket_test.go

@@ -0,0 +1,75 @@
+package main
+
+import (
+	"path/filepath"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// TestSocketPathEnvOverride verifies that BD_SOCKET env var overrides default socket path.
+func TestSocketPathEnvOverride(t *testing.T) {
+	// Create isolated temp directory
+	tmpDir := t.TempDir()
+	customSocket := filepath.Join(tmpDir, "custom.sock")
+
+	// Set environment for isolation
+	t.Setenv("BD_SOCKET", customSocket)
+
+	// Verify getSocketPath returns custom path
+	got := getSocketPath()
+	assert.Equal(t, customSocket, got)
+}
+
+// TestSocketPathForPIDEnvOverride verifies that BD_SOCKET env var overrides PID-derived path.
+func TestSocketPathForPIDEnvOverride(t *testing.T) {
+	// Create isolated temp directory
+	tmpDir := t.TempDir()
+	customSocket := filepath.Join(tmpDir, "custom.sock")
+
+	// Set environment for isolation
+	t.Setenv("BD_SOCKET", customSocket)
+
+	// Verify getSocketPathForPID returns custom path (ignoring pidFile)
+	pidFile := "/some/other/path/daemon.pid"
+	got := getSocketPathForPID(pidFile)
+	assert.Equal(t, customSocket, got)
+}
+
+// TestSocketPathDefaultBehavior verifies default behavior when BD_SOCKET is not set.
+func TestSocketPathDefaultBehavior(t *testing.T) {
+	// Ensure BD_SOCKET is not set (t.Setenv restores after test)
+	t.Setenv("BD_SOCKET", "")
+
+	// Verify getSocketPathForPID derives from PID file path
+	pidFile := "/path/to/.beads/daemon.pid"
+	got := getSocketPathForPID(pidFile)
+	assert.Equal(t, "/path/to/.beads/bd.sock", got)
+}
+
+// TestDaemonSocketIsolation demonstrates that two test instances can use different sockets.
+// This is the key pattern for parallel test isolation.
+func TestDaemonSocketIsolation(t *testing.T) {
+	// Simulate two parallel tests with different socket paths
+	tests := []struct {
+		name       string
+		sockSuffix string
+	}{
+		{"instance_a", "a.sock"},
+		{"instance_b", "b.sock"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Each sub-test gets isolated socket path in its own temp dir
+			socketPath := filepath.Join(t.TempDir(), tt.sockSuffix)
+			t.Setenv("BD_SOCKET", socketPath)
+
+			got := getSocketPath()
+			assert.Equal(t, socketPath, got)
+
+			// Verify paths are unique per instance
+			assert.Contains(t, got, tt.sockSuffix)
+		})
+	}
+}

go.mod

@@ -10,9 +10,12 @@ require (
 	github.com/charmbracelet/huh v0.8.0
 	github.com/charmbracelet/lipgloss v1.1.0
 	github.com/fsnotify/fsnotify v1.9.0
+	github.com/muesli/termenv v0.16.0
 	github.com/ncruces/go-sqlite3 v0.30.4
+	github.com/olebedev/when v1.1.0
 	github.com/spf13/cobra v1.10.2
 	github.com/spf13/viper v1.21.0
+	github.com/stretchr/testify v1.11.1
 	github.com/tetratelabs/wazero v1.11.0
 	golang.org/x/mod v0.31.0
 	golang.org/x/sys v0.39.0
@@ -34,6 +37,7 @@ require (
 	github.com/charmbracelet/x/cellbuf v0.0.13 // indirect
 	github.com/charmbracelet/x/exp/strings v0.0.0-20240722160745-212f7b056ed0 // indirect
 	github.com/charmbracelet/x/term v0.2.1 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
 	github.com/erikgeiser/coninput v0.0.0-20211004153227-1c3628e74d0f // indirect
 	github.com/go-viper/mapstructure/v2 v2.4.0 // indirect
@@ -46,11 +50,10 @@ require (
 	github.com/mitchellh/hashstructure/v2 v2.0.2 // indirect
 	github.com/muesli/ansi v0.0.0-20230316100256-276c6243b2f6 // indirect
 	github.com/muesli/cancelreader v0.2.2 // indirect
-	github.com/muesli/termenv v0.16.0 // indirect
 	github.com/ncruces/julianday v1.0.0 // indirect
-	github.com/olebedev/when v1.1.0 // indirect
 	github.com/pelletier/go-toml/v2 v2.2.4 // indirect
 	github.com/pkg/errors v0.8.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/rivo/uniseg v0.4.7 // indirect
 	github.com/sagikazarmark/locafero v0.11.0 // indirect
 	github.com/sourcegraph/conc v0.3.1-0.20240121214520-5f936abd7ae8 // indirect