refactor(agent): unify preview and runtime arg builders

internal/agent/codex.go

@@ -105,27 +105,30 @@ func (a *CodexAgent) CommandName() string {
 
 func (a *CodexAgent) CommandLine() string {
 	agenticMode := a.Agentic || AllowUnsafeAgents()
-	// Show representative args (repo path is a runtime value)
-	sessionID := sanitizedResumeSessionID(a.SessionID)
-	args := []string{"exec", "--json"}
-	if sessionID != "" {
-		args = []string{"exec", "resume", "--json", sessionID}
-	}
-	if agenticMode {
-		args = append(args, codexDangerousFlag)
-	} else {
-		args = append(args, "--sandbox", "read-only")
-	}
-	if a.Model != "" {
-		args = append(args, "-m", a.Model)
-	}
-	if effort := a.codexReasoningEffort(); effort != "" {
-		args = append(args, "-c", fmt.Sprintf(`model_reasoning_effort="%s"`, effort))
-	}
+	args := a.commandArgs(codexArgOptions{
+		agenticMode: agenticMode,
+		autoApprove: !agenticMode,
+		preview:     true,
+	})
 	return a.Command + " " + strings.Join(args, " ")
 }
 
 func (a *CodexAgent) buildArgs(repoPath string, agenticMode, autoApprove bool) []string {
+	return a.commandArgs(codexArgOptions{
+		repoPath:    repoPath,
+		agenticMode: agenticMode,
+		autoApprove: autoApprove,
+	})
+}
+
+type codexArgOptions struct {
+	repoPath    string
+	agenticMode bool
+	autoApprove bool
+	preview     bool
+}
+
+func (a *CodexAgent) commandArgs(opts codexArgOptions) []string {
 	sessionID := sanitizedResumeSessionID(a.SessionID)
 	args := []string{
 		"exec",
@@ -134,18 +137,18 @@ func (a *CodexAgent) buildArgs(repoPath string, agenticMode, autoApprove bool) [
 		args = append(args, "resume")
 	}
 	args = append(args, "--json")
-	if agenticMode {
+	if opts.agenticMode {
 		args = append(args, codexDangerousFlag)
 	}
-	if autoApprove {
+	if opts.autoApprove {
 		// Use read-only sandbox for review mode instead of --full-auto
 		// (which implies --sandbox workspace-write). Background review
 		// jobs run in the user's repo and must not take index.lock.
 		args = append(args, "--sandbox", "read-only")
 	}
-	args = append(args,
-		"-C", repoPath,
-	)
+	if !opts.preview {
+		args = append(args, "-C", opts.repoPath)
+	}
 	if a.Model != "" {
 		args = append(args, "-m", a.Model)
 	}
@@ -155,9 +158,11 @@ func (a *CodexAgent) buildArgs(repoPath string, agenticMode, autoApprove bool) [
 	if sessionID != "" {
 		args = append(args, sessionID)
 	}
-	// "-" must come after all flags to read prompt from stdin
-	// This avoids Windows command line length limits (~32KB)
-	args = append(args, "-")
+	if !opts.preview {
+		// "-" must come after all flags to read prompt from stdin
+		// This avoids Windows command line length limits (~32KB)
+		args = append(args, "-")
+	}
 	return args
 }
 

internal/agent/codex_test.go

@@ -89,6 +89,18 @@ func TestCodexBuildArgsRejectsInvalidSessionResume(t *testing.T) {
 	assertNotContainsArg(t, args, "-bad-session")
 }
 
+func TestCodexCommandLineOmitsRuntimeOnlyArgs(t *testing.T) {
+	a := NewCodexAgent("codex").WithSessionID("session-123").WithModel("o4-mini").(*CodexAgent)
+
+	cmdLine := a.CommandLine()
+
+	assert.Contains(t, cmdLine, "exec resume --json")
+	assert.Contains(t, cmdLine, "session-123")
+	assert.Contains(t, cmdLine, "--sandbox read-only")
+	assert.NotContains(t, cmdLine, " -C ")
+	assert.False(t, strings.HasSuffix(cmdLine, " -"), "command line should omit stdin marker: %q", cmdLine)
+}
+
 func TestCodexSupportsDangerousFlagAllowsNonZeroHelp(t *testing.T) {
 	cmdPath := writeTempCommand(t, "#!/bin/sh\necho \"usage "+codexDangerousFlag+"\"; exit 1\n")
 

internal/agent/copilot.go

@@ -50,16 +50,7 @@ var copilotReviewDenyTools = []string{
 // In review mode, destructive tools are denied. In agentic mode, all tools
 // are allowed without restriction.
 func (a *CopilotAgent) buildArgs(agenticMode bool) []string {
-	args := []string{"-s", "--allow-all-tools"}
-	if a.Model != "" {
-		args = append(args, "--model", a.Model)
-	}
-	if !agenticMode {
-		for _, tool := range copilotReviewDenyTools {
-			args = append(args, "--deny-tool", tool)
-		}
-	}
-	return args
+	return a.commandArgs(agenticMode, true)
 }
 
 // CopilotAgent runs code reviews using the GitHub Copilot CLI
@@ -122,10 +113,8 @@ func (a *CopilotAgent) CommandName() string {
 }
 
 func (a *CopilotAgent) CommandLine() string {
-	var args []string
-	if a.Model != "" {
-		args = append(args, "--model", a.Model)
-	}
+	agenticMode := a.Agentic || AllowUnsafeAgents()
+	args := a.commandArgs(agenticMode, false)
 	return a.Command + " " + strings.Join(args, " ")
 }
 
@@ -139,11 +128,9 @@ func (a *CopilotAgent) Review(ctx context.Context, repoPath, commitSHA, prompt s
 
 	var args []string
 	if supported {
-		args = a.buildArgs(agenticMode)
+		args = a.commandArgs(agenticMode, true)
 	} else {
-		if a.Model != "" {
-			args = append(args, "--model", a.Model)
-		}
+		args = a.commandArgs(agenticMode, false)
 	}
 
 	cmd := exec.CommandContext(ctx, a.Command, args...)
@@ -175,6 +162,22 @@ func (a *CopilotAgent) Review(ctx context.Context, repoPath, commitSHA, prompt s
 	return result, nil
 }
 
+func (a *CopilotAgent) commandArgs(agenticMode, includePermissions bool) []string {
+	args := []string{}
+	if includePermissions {
+		args = append(args, "-s", "--allow-all-tools")
+	}
+	if a.Model != "" {
+		args = append(args, "--model", a.Model)
+	}
+	if includePermissions && !agenticMode {
+		for _, tool := range copilotReviewDenyTools {
+			args = append(args, "--deny-tool", tool)
+		}
+	}
+	return args
+}
+
 func init() {
 	Register(NewCopilotAgent(""))
 }

internal/agent/copilot_test.go

@@ -75,6 +75,16 @@ func TestCopilotBuildArgs(t *testing.T) {
 	})
 }
 
+func TestCopilotCommandLineUsesPreviewArgs(t *testing.T) {
+	a := NewCopilotAgent("copilot").WithModel("gpt-4o").(*CopilotAgent)
+
+	cmdLine := a.CommandLine()
+
+	assert.Contains(t, cmdLine, "--model gpt-4o")
+	assert.NotContains(t, cmdLine, "--allow-all-tools")
+	assert.NotContains(t, cmdLine, "--deny-tool")
+}
+
 func TestCopilotReview(t *testing.T) {
 	skipIfWindows(t)
 

internal/agent/cursor.go

@@ -65,18 +65,7 @@ func (a *CursorAgent) CommandName() string {
 
 func (a *CursorAgent) CommandLine() string {
 	agenticMode := a.Agentic || AllowUnsafeAgents()
-	// Show flags without the prompt (piped via stdin)
-	args := []string{"-p", "--output-format", "stream-json"}
-	model := a.Model
-	if model == "" {
-		model = "auto"
-	}
-	args = append(args, "--model", model)
-	if agenticMode {
-		args = append(args, "--force")
-	} else {
-		args = append(args, "--mode", "plan")
-	}
+	args := a.buildArgs(agenticMode)
 	return a.Command + " " + strings.Join(args, " ")
 }
 

internal/agent/cursor_test.go

@@ -65,6 +65,13 @@ func TestCursorBuildArgs_Table(t *testing.T) {
 	}
 }
 
+func TestCursorCommandLineUsesBuildArgs(t *testing.T) {
+	a := NewCursorAgent("agent").WithModel("gpt-5.2-codex-high").WithAgentic(true).(*CursorAgent)
+
+	want := strings.Join(a.buildArgs(true), " ")
+	assert.Equal(t, "agent "+want, a.CommandLine())
+}
+
 func setupMockCursorAgent(t *testing.T, opts MockCLIOpts) (*CursorAgent, *MockCLIResult) {
 	t.Helper()
 	skipIfWindows(t)

internal/agent/droid.go

@@ -65,15 +65,7 @@ func (a *DroidAgent) CommandName() string {
 
 func (a *DroidAgent) CommandLine() string {
 	agenticMode := a.Agentic || AllowUnsafeAgents()
-	args := []string{"exec"}
-	if agenticMode {
-		args = append(args, "--auto", "medium")
-	} else {
-		args = append(args, "--auto", "low")
-	}
-	if effort := a.droidReasoningEffort(); effort != "" {
-		args = append(args, "--reasoning-effort", effort)
-	}
+	args := a.buildArgs(agenticMode)
 	return a.Command + " " + strings.Join(args, " ")
 }
 

internal/agent/droid_test.go

@@ -2,6 +2,7 @@ package agent
 
 import (
 	"context"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 	"os"
 	"path/filepath"
@@ -64,6 +65,13 @@ func TestDroidBuildArgs(t *testing.T) {
 	}
 }
 
+func TestDroidCommandLineUsesBuildArgs(t *testing.T) {
+	a := NewDroidAgent("droid").WithReasoning(ReasoningThorough).WithAgentic(true).(*DroidAgent)
+
+	want := strings.Join(a.buildArgs(true), " ")
+	assert.Equal(t, "droid "+want, a.CommandLine())
+}
+
 func TestDroidName(t *testing.T) {
 	a := NewDroidAgent("")
 	require.Equal(t, "droid", a.Name(), "expected name 'droid', got %s", a.Name())

internal/agent/pi.go

@@ -107,18 +107,13 @@ func (a *PiAgent) CommandName() string {
 
 func (a *PiAgent) CommandLine() string {
 	args := a.buildArgs("")
-	if len(args) == 0 {
-		args = []string{"-p", "--mode", "json"}
-	}
 	return a.Command + " " + strings.Join(args, " ")
 }
 
-func (a *PiAgent) buildArgs(repoPath string) []string {
+func (a *PiAgent) buildArgs(sessionPath string) []string {
 	args := []string{"-p", "--mode", "json"}
-	if repoPath != "" {
-		if sessionPath := resolvePiSessionPath(sanitizedResumeSessionID(a.SessionID)); sessionPath != "" {
-			args = append(args, "--session", sessionPath)
-		}
+	if sessionPath != "" {
+		args = append(args, "--session", sessionPath)
 	}
 	if a.Provider != "" {
 		args = append(args, "--provider", a.Provider)
@@ -165,7 +160,8 @@ func (a *PiAgent) Review(
 		return "", fmt.Errorf("close temp prompt file: %w", err)
 	}
 
-	args := a.buildArgs(repoPath)
+	sessionPath := resolvePiSessionPath(sanitizedResumeSessionID(a.SessionID))
+	args := a.buildArgs(sessionPath)
 
 	// Add the prompt file as an input argument (prefixed with @)
 	// Pi treats @files as context/input.

internal/agent/pi_test.go

@@ -73,3 +73,20 @@ func TestPiReviewSessionFlag(t *testing.T) {
 	assertContainsArg(t, args, "--mode")
 	assertContainsArg(t, args, "json")
 }
+
+func TestPiCommandLineOmitsResolvedSessionPath(t *testing.T) {
+	dataDir := t.TempDir()
+	t.Setenv("PI_CODING_AGENT_DIR", dataDir)
+
+	sessionID := "46109439-3160-40f0-81e7-7dfa4f3647b3"
+	sessionPath := filepath.Join(dataDir, "sessions", "--repo--", "2026-03-08T18-44-39-718Z_"+sessionID+".jsonl")
+	require.NoError(t, os.MkdirAll(filepath.Dir(sessionPath), 0o755))
+	require.NoError(t, os.WriteFile(sessionPath, []byte("{}\n"), 0o644))
+
+	a := NewPiAgent("pi").WithSessionID(sessionID).(*PiAgent)
+	cmdLine := a.CommandLine()
+
+	assert.NotContains(t, cmdLine, "--session")
+	assert.NotContains(t, cmdLine, sessionPath)
+	assert.Contains(t, cmdLine, "-p --mode json")
+}