add TUIFastRefreshInterval flag to flags.Config

Add TUIFastRefreshInterval time.Duration to flags.Config struct with a
default of 250ms and register it as the -tui-fast-refresh CLI flag so
callers can tune or disable the high-frequency TUI refresh cadence for
the flamegraph and stream tabs.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

2 files changed, 51 insertions, 9 deletions

diff --git a/internal/flags/flags.go b/internal/flags/flags.go
index a46f6b3..e7171ce 100644
--- a/internal/flags/flags.go
+++ b/internal/flags/flags.go
@@ -54,6 +54,10 @@ type Config struct {
 	// LiveInterval is the refresh interval for the synthetic live flamegraph
 	// used when TestLiveFlames is active.
 	LiveInterval time.Duration
+	// TUIFastRefreshInterval is the high-frequency refresh cadence for the TUI
+	// flamegraph and stream tabs. A value of 0 disables high-frequency refresh,
+	// falling back to the standard Bubble Tea tick rate.
+	TUIFastRefreshInterval time.Duration
 	// TUIExportEnable allows the TUI to write CSV snapshot export files.
 	TUIExportEnable bool
 	// CollapsedFields lists the event fields used as flamegraph collapse keys.
@@ -82,15 +86,16 @@ const DefaultResetTimer = 30 * time.Second
 // NewFlags returns a configuration instance initialized with project defaults.
 func NewFlags() Config {
 	return Config{
-		PidFilter:       -1,
-		TidFilter:       -1,
-		EventMapSize:    appconfig.DefaultEventMapSize,
-		Duration:        900,
-		LiveInterval:    200 * time.Millisecond,
-		TUIExportEnable: true,
-		CollapsedFields: []string{"comm", "tracepoint", "path"},
-		CountField:      "count",
-		ResetTimer:      DefaultResetTimer,
+		PidFilter:              -1,
+		TidFilter:              -1,
+		EventMapSize:           appconfig.DefaultEventMapSize,
+		Duration:               900,
+		LiveInterval:           200 * time.Millisecond,
+		TUIFastRefreshInterval: 250 * time.Millisecond,
+		TUIExportEnable:        true,
+		CollapsedFields:        []string{"comm", "tracepoint", "path"},
+		CountField:             "count",
+		ResetTimer:             DefaultResetTimer,
 	}
 }
 
@@ -170,6 +175,8 @@ func registerFlags(fs *flag.FlagSet, cfg *Config) (tpsAttach, tpsExclude, fields
 	fs.BoolVar(&cfg.TestFlames, "testflames", false, "Run TUI with static synthetic flamegraph data for keyboard-navigation testing")
 	fs.BoolVar(&cfg.TestLiveFlames, "testliveflames", false, "Run TUI with continuously-updating synthetic flamegraph data for live keyboard-navigation testing")
 	fs.DurationVar(&cfg.LiveInterval, "live-interval", cfg.LiveInterval, "Synthetic live flamegraph refresh interval for --testliveflames")
+	fs.DurationVar(&cfg.TUIFastRefreshInterval, "tui-fast-refresh", cfg.TUIFastRefreshInterval,
+		"High-frequency refresh interval for TUI flamegraph and stream tabs (0 = disable high-frequency refresh)")
 	fs.BoolVar(&cfg.TUIExportEnable, "tuiExport", cfg.TUIExportEnable, "Enable TUI CSV snapshot export files (separate from Parquet recording)")
 	fs.DurationVar(&cfg.ResetTimer, "resetTimer", cfg.ResetTimer,
 		"Auto-reset interval for aggregate dashboard state (flamegraph trie + stats engine); set to 0 to disable")
diff --git a/internal/flags/flags_test.go b/internal/flags/flags_test.go
index d4697d6..1feeafd 100644
--- a/internal/flags/flags_test.go
+++ b/internal/flags/flags_test.go
@@ -255,3 +255,38 @@ func TestParsePositiveMapSizeAccepted(t *testing.T) {
 		t.Fatalf("EventMapSize = %d, want 8192", cfg.EventMapSize)
 	}
 }
+
+func TestParseTUIFastRefreshDefault(t *testing.T) {
+	// Default should be 250ms — the high-frequency refresh cadence used by
+	// the flamegraph and stream tabs when no explicit flag is provided.
+	cfg, err := parseForTest(t)
+	if err != nil {
+		t.Fatalf("parse returned error: %v", err)
+	}
+	if cfg.TUIFastRefreshInterval != 250*time.Millisecond {
+		t.Fatalf("default TUIFastRefreshInterval = %v, want 250ms", cfg.TUIFastRefreshInterval)
+	}
+}
+
+func TestParseTUIFastRefreshOverride(t *testing.T) {
+	// An explicit -tui-fast-refresh value must be respected and stored on cfg.
+	cfg, err := parseForTest(t, "-tui-fast-refresh", "100ms")
+	if err != nil {
+		t.Fatalf("parse returned error: %v", err)
+	}
+	if cfg.TUIFastRefreshInterval != 100*time.Millisecond {
+		t.Fatalf("TUIFastRefreshInterval = %v, want 100ms", cfg.TUIFastRefreshInterval)
+	}
+}
+
+func TestParseTUIFastRefreshZeroDisables(t *testing.T) {
+	// A zero value is valid and means "disable high-frequency refresh",
+	// falling back to the default Bubble Tea tick rate.
+	cfg, err := parseForTest(t, "-tui-fast-refresh", "0")
+	if err != nil {
+		t.Fatalf("parse returned error: %v", err)
+	}
+	if cfg.TUIFastRefreshInterval != 0 {
+		t.Fatalf("TUIFastRefreshInterval = %v, want 0 (disabled)", cfg.TUIFastRefreshInterval)
+	}
+}