From e61e09cc1ea017a783b05eebb3239c5cecad314a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Carlos=20Flor=C3=AAncio?= <carlosmflorencio@gmail.com>
Date: Tue, 21 Apr 2026 19:57:22 +0100
Subject: [PATCH] fix(backend): prevent duplicate --allow-indexing in Auggie
 passthrough preview (#675)

---
 .../agent/settings/controller/agent_config.go |  13 ++-
 .../settings/controller/controller_test.go    | 104 ++++++++++++++++++
 2 files changed, 114 insertions(+), 3 deletions(-)

diff --git a/apps/backend/internal/agent/settings/controller/agent_config.go b/apps/backend/internal/agent/settings/controller/agent_config.go
index 5a7e42e0b6..d2aed016d4 100644
--- a/apps/backend/internal/agent/settings/controller/agent_config.go
+++ b/apps/backend/internal/agent/settings/controller/agent_config.go
@@ -183,6 +183,13 @@ func (c *Controller) PreviewAgentCommand(ctx context.Context, agentName string,
 	// Tolerate malformed entries silently — the preview is informational.
 	cliFlagTokens, _ := cliflags.Resolve(cliFlagsFromDTO(req.CLIFlags))
 
+	// Passthrough: BuildPassthroughCommand emits permission flags via Settings();
+	// the launch path (manager_passthrough.go) does not append CLIFlagTokens for
+	// passthrough, so the preview must match — otherwise permission flags that
+	// the legacy allow_indexing backfill also pushes into CLIFlags get rendered
+	// twice (e.g. Auggie's --allow-indexing).
+	// ACP: mirror lifecycle.CommandBuilder.BuildCommand by appending CLIFlagTokens
+	// after the agent's BuildCommand.
 	var cmd agents.Command
 	if ptAgent, ok := agentConfig.(agents.PassthroughAgent); ok && req.CLIPassthrough {
 		cmd = ptAgent.BuildPassthroughCommand(agents.PassthroughOptions{
@@ -195,9 +202,9 @@ func (c *Controller) PreviewAgentCommand(ctx context.Context, agentName string,
 			PermissionValues: req.PermissionSettings,
 			CLIFlagTokens:    cliFlagTokens,
 		})
-	}
-	if len(cliFlagTokens) > 0 {
-		cmd = cmd.With().Flag(cliFlagTokens...).Build()
+		if len(cliFlagTokens) > 0 {
+			cmd = cmd.With().Flag(cliFlagTokens...).Build()
+		}
 	}
 
 	return &dto.CommandPreviewResponse{
diff --git a/apps/backend/internal/agent/settings/controller/controller_test.go b/apps/backend/internal/agent/settings/controller/controller_test.go
index dcf9dd04b3..7223fef169 100644
--- a/apps/backend/internal/agent/settings/controller/controller_test.go
+++ b/apps/backend/internal/agent/settings/controller/controller_test.go
@@ -288,6 +288,110 @@ func TestController_PreviewAgentCommand_PassthroughDisabled(t *testing.T) {
 	}
 }
 
+// TestController_PreviewAgentCommand_PassthroughDoesNotDuplicateCLIFlag regresses
+// the Auggie case where enabling CLI passthrough caused --allow-indexing to be
+// emitted twice: once by BuildPassthroughCommand via Settings() and again by an
+// unconditional CLIFlagTokens append in the preview. The launch path only adds
+// it via Settings(), so the preview must match.
+func TestController_PreviewAgentCommand_PassthroughDoesNotDuplicateCLIFlag(t *testing.T) {
+	permSettings := map[string]agents.PermissionSetting{
+		"allow_indexing": {
+			Supported:   true,
+			ApplyMethod: "cli_flag",
+			CLIFlag:     "--allow-indexing",
+		},
+	}
+	agentList := map[string]agents.Agent{
+		"auggie": &testAgent{
+			id:      "auggie",
+			name:    "auggie",
+			enabled: true,
+			runtime: &agents.RuntimeConfig{
+				Cmd: agents.NewCommand("auggie"),
+			},
+			StandardPassthrough: agents.StandardPassthrough{
+				Cfg: agents.PassthroughConfig{
+					Supported:      true,
+					PassthroughCmd: agents.NewCommand("npx", "-y", "@augmentcode/auggie"),
+				},
+				PermSettings: permSettings,
+			},
+			permissionSettings: permSettings,
+		},
+	}
+
+	controller := newTestController(agentList)
+
+	// Simulate the post-backfill state: allow_indexing toggle ON and the legacy
+	// backfill has seeded --allow-indexing into CLIFlags. Both sources would
+	// previously emit the flag.
+	req := CommandPreviewRequest{
+		PermissionSettings: map[string]bool{"allow_indexing": true},
+		CLIPassthrough:     true,
+		CLIFlags: []dto.CLIFlagDTO{
+			{Flag: "--allow-indexing", Enabled: true},
+		},
+	}
+
+	result, err := controller.PreviewAgentCommand(context.Background(), "auggie", req)
+	if err != nil {
+		t.Fatalf("PreviewAgentCommand() error = %v", err)
+	}
+
+	count := 0
+	for _, part := range result.Command {
+		if part == "--allow-indexing" {
+			count++
+		}
+	}
+	if count != 1 {
+		t.Errorf("PreviewAgentCommand() emitted --allow-indexing %d times, want 1; got %v", count, result.Command)
+	}
+}
+
+// TestController_PreviewAgentCommand_ACPAppendsCLIFlagsOnce locks in that the
+// non-passthrough (ACP) branch still appends user-configured CLI flags exactly
+// once. Auggie's real BuildCommand intentionally does not emit --allow-indexing;
+// the flag must come through CLIFlagTokens.
+func TestController_PreviewAgentCommand_ACPAppendsCLIFlagsOnce(t *testing.T) {
+	agentList := map[string]agents.Agent{
+		"auggie": &testAgent{
+			id:      "auggie",
+			name:    "auggie",
+			enabled: true,
+			runtime: &agents.RuntimeConfig{
+				Cmd: agents.NewCommand("auggie", "--acp"),
+			},
+			// No permissionSettings: mirrors Auggie's real BuildCommand which
+			// does not emit --allow-indexing — it flows through CLIFlags only.
+		},
+	}
+
+	controller := newTestController(agentList)
+
+	req := CommandPreviewRequest{
+		CLIPassthrough: false,
+		CLIFlags: []dto.CLIFlagDTO{
+			{Flag: "--allow-indexing", Enabled: true},
+		},
+	}
+
+	result, err := controller.PreviewAgentCommand(context.Background(), "auggie", req)
+	if err != nil {
+		t.Fatalf("PreviewAgentCommand() error = %v", err)
+	}
+
+	count := 0
+	for _, part := range result.Command {
+		if part == "--allow-indexing" {
+			count++
+		}
+	}
+	if count != 1 {
+		t.Errorf("PreviewAgentCommand() emitted --allow-indexing %d times, want 1; got %v", count, result.Command)
+	}
+}
+
 func TestBuildCommandString(t *testing.T) {
 	tests := []struct {
 		name     string