fix(board): forward directory overrides to spawned agents

pkg/board/tmux.go

@@ -9,6 +9,8 @@ import (
 	"strconv"
 	"strings"
 	"sync"
+
+	"github.com/docker/docker-agent/pkg/paths"
 )
 
 // tmuxSessions manages the tmux sessions the board runs its agents in.
@@ -171,6 +173,16 @@ func applyServerDefaults(ctx context.Context) {
 // owns sessionID and passes it via --session: the first run creates that
 // session, later runs resume it.
 //
+// --config-dir, --data-dir, and --cache-dir forward the board's own
+// directories so the agent resolves the same aliases, creates its worktree
+// and session under the data dir the board watches, and shares the board's
+// caches. Directory overrides are process-local flags, not inherited env,
+// so without forwarding an agent spawned in an environment whose $HOME
+// differs from the board's directories (e.g. a docker sandbox with the
+// host dirs bind-mounted) would silently use its own empty config and a
+// data dir the board never looks at. On a host with no overrides this
+// forwards the defaults — a no-op.
+//
 // --listen exposes the run's control plane on listenSocket (a unix socket
 // the board owns), so the board can observe and drive the session over HTTP
 // instead of scraping the terminal.
@@ -188,8 +200,10 @@ func agentCommand(agent, sessionID, listenSocket, worktreeName, worktreeBase, pr
 	if err != nil {
 		bin = "docker-agent"
 	}
-	cmd := fmt.Sprintf("%s run %s --yolo --session %s --listen %s",
-		shQuote(bin), shQuote(agent), shQuote(sessionID), shQuote("unix://"+listenSocket))
+	cmd := fmt.Sprintf("%s run %s --yolo --config-dir %s --data-dir %s --cache-dir %s --session %s --listen %s",
+		shQuote(bin), shQuote(agent),
+		shQuote(paths.GetConfigDir()), shQuote(paths.GetDataDir()), shQuote(paths.GetCacheDir()),
+		shQuote(sessionID), shQuote("unix://"+listenSocket))
 	if worktreeName != "" {
 		cmd += fmt.Sprintf(" --worktree=%s --worktree-base %s", shQuote(worktreeName), shQuote(worktreeBase))
 	}

pkg/board/tmux_test.go

@@ -5,6 +5,8 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+
+	"github.com/docker/docker-agent/pkg/paths"
 )
 
 func TestShQuote(t *testing.T) {
@@ -20,16 +22,46 @@ func TestAgentCommand(t *testing.T) {
 
 	// First run: creates the worktree from the base.
 	cmd := agentCommand("coder", "sess1", "/tmp/a.sock", "board-abc", "origin/main", "do the thing")
-	assert.Contains(t, cmd, " run 'coder' --yolo --session 'sess1' --listen 'unix:///tmp/a.sock'")
+	assert.Contains(t, cmd, " run 'coder' --yolo ")
+	assert.Contains(t, cmd, " --session 'sess1' --listen 'unix:///tmp/a.sock'")
 	assert.Contains(t, cmd, "--worktree='board-abc' --worktree-base 'origin/main'")
 	assert.True(t, strings.HasSuffix(cmd, " 'do the thing'"))
 
+	// The board's config, data, and cache dirs are forwarded so the agent
+	// resolves the same aliases and creates its worktree where the board
+	// watches, even when the board runs with directory overrides (e.g. in a
+	// sandbox whose $HOME differs from the mounted host directories).
+	assert.Contains(t, cmd, " --config-dir "+shQuote(paths.GetConfigDir())+" ")
+	assert.Contains(t, cmd, " --data-dir "+shQuote(paths.GetDataDir())+" ")
+	assert.Contains(t, cmd, " --cache-dir "+shQuote(paths.GetCacheDir())+" ")
+
 	// Resume: no worktree flags, no prompt.
 	cmd = agentCommand("coder", "sess1", "/tmp/a.sock", "", "", "")
 	assert.NotContains(t, cmd, "--worktree")
 	assert.True(t, strings.HasSuffix(cmd, "--listen 'unix:///tmp/a.sock'"))
 }
 
+// TestAgentCommandForwardsDirOverrides covers the scenario the forwarding
+// exists for: the board running with directory overrides. Not parallel: it
+// mutates the process-global overrides, and restores them before returning
+// — during the serial phase, before parallel tests resume.
+func TestAgentCommandForwardsDirOverrides(t *testing.T) {
+	configDir, dataDir, cacheDir := t.TempDir(), t.TempDir(), t.TempDir()
+	paths.SetConfigDir(configDir)
+	paths.SetDataDir(dataDir)
+	paths.SetCacheDir(cacheDir)
+	t.Cleanup(func() {
+		paths.SetConfigDir("")
+		paths.SetDataDir("")
+		paths.SetCacheDir("")
+	})
+
+	cmd := agentCommand("coder", "sess1", "/tmp/a.sock", "", "", "")
+	assert.Contains(t, cmd, " --config-dir "+shQuote(configDir)+" ")
+	assert.Contains(t, cmd, " --data-dir "+shQuote(dataDir)+" ")
+	assert.Contains(t, cmd, " --cache-dir "+shQuote(cacheDir)+" ")
+}
+
 func TestTmuxFormatEscape(t *testing.T) {
 	t.Parallel()