refactor: pass flags.Config explicitly, remove flags.Get() from library code (task 429)

flags.Get() (global mutable singleton) was called inside library packages,
coupling them to global state and making tests fragile (DIP violation).

- internal.Run() now takes an explicit flags.Config; main.go calls
  flags.Get() once at the CLI boundary and passes it in.
- tui.Run(), RunWithTraceStarter(), RunTestFlamesWithTraceStarter() removed;
  callers already used the WithConfig variants directly.
- tui.NewModel() preserved for test ergonomics but now uses flags.NewFlags()
  (pure defaults) instead of flags.Get() (global state).
- Tests updated to use NewModelWithConfig() with explicit config structs
  instead of flags.Set*() + NewModel(), eliminating all test-level
  global-state mutation.

flags.Get() is now called only in cmd/ior/main.go, the correct boundary.

Co-Authored-By: Claude Sonnet 4.6 (1M context) <noreply@anthropic.com>

2 files changed, 28 insertions, 106 deletions

diff --git a/internal/tui/tui.go b/internal/tui/tui.go
index ef94748..432fc14 100644
--- a/internal/tui/tui.go
+++ b/internal/tui/tui.go
@@ -5,7 +5,6 @@ import (
 	"errors"
 	"fmt"
 	"log"
-	"os"
 	"strconv"
 	"strings"
 	"sync"
@@ -231,16 +230,6 @@ func TraceFiltersFromContext(ctx context.Context) (globalfilter.Filter, bool) {
 	return filters.filter.Clone(), true
 }
 
-// Run starts the TUI program in alternate screen mode.
-func Run() error {
-	return RunWithTraceStarter(defaultTraceStarter)
-}
-
-// RunWithTraceStarter starts the TUI program with a custom trace starter.
-func RunWithTraceStarter(starter TraceStarter) error {
-	return RunWithTraceStarterConfig(flags.Get(), starter)
-}
-
 // RunWithTraceStarterConfig starts the TUI with explicit runtime flags.
 func RunWithTraceStarterConfig(cfg flags.Config, starter TraceStarter) error {
 	model := newModelWithRuntimeConfig(cfg.PidFilter, filterFromConfig(cfg), cfg.PidFilter, cfg.TidFilter, cfg.TUIExportEnable, starter)
@@ -249,12 +238,6 @@ func RunWithTraceStarterConfig(cfg flags.Config, starter TraceStarter) error {
 	return err
 }
 
-// RunTestFlamesWithTraceStarter starts the TUI directly on dashboard/flame view
-// with a synthetic static flamegraph source.
-func RunTestFlamesWithTraceStarter(starter TraceStarter) error {
-	return RunTestFlamesWithTraceStarterConfig(flags.Get(), starter)
-}
-
 // RunTestFlamesWithTraceStarterConfig starts test-flames mode with explicit runtime flags.
 func RunTestFlamesWithTraceStarterConfig(cfg flags.Config, starter TraceStarter) error {
 	model := newModelWithRuntimeConfig(1, filterFromConfig(cfg), 1, -1, cfg.TUIExportEnable, starter)
@@ -317,9 +300,10 @@ type pickerReturnState struct {
 	tidFilter int
 }
 
-// NewModel creates the top-level TUI model.
+// NewModel creates the top-level TUI model with default runtime flags.
+// Prefer NewModelWithConfig to pass parsed CLI config explicitly.
 func NewModel(initialPID int, startTrace TraceStarter) Model {
-	return NewModelWithConfig(flags.Get(), initialPID, startTrace)
+	return NewModelWithConfig(flags.NewFlags(), initialPID, startTrace)
 }
 
 // NewModelWithConfig creates the top-level TUI model with explicit runtime flags.
@@ -500,17 +484,6 @@ func (m Model) canHandleDashboardShortcut(msg tea.KeyPressMsg) bool {
 		!m.dashboard.BlocksGlobalShortcuts(msg)
 }
 
-func (m Model) canQuitFromMainDashboard(msg tea.KeyPressMsg) bool {
-	return m.screen == ScreenDashboard &&
-		!m.attaching &&
-		m.lastErr == nil &&
-		!m.filterModal.Visible() &&
-		!m.exporter.Visible() &&
-		!m.recordModal.Visible() &&
-		!m.probeModal.Visible() &&
-		!m.dashboard.BlocksGlobalShortcuts(msg)
-}
-
 func (m Model) shouldCancelPickerToDashboard(msg tea.KeyPressMsg) bool {
 	return m.screen == ScreenPIDPicker &&
 		m.pickerReturn != nil &&
@@ -537,7 +510,7 @@ func (m Model) handleGlobalKeyPress(msg tea.KeyPressMsg) (tea.Model, tea.Cmd, bo
 		return next, cmd, true
 	}
 	if key.Matches(msg, m.keys.Quit) {
-		if m.canQuitFromMainDashboard(msg) {
+		if m.canHandleDashboardShortcut(msg) {
 			if err := m.stopRecording(); err != nil {
 				m.lastErr = err
 				return m, nil, true
@@ -848,31 +821,9 @@ func defaultTraceStarter(context.Context) error {
 	return nil
 }
 
+// filterFromConfig delegates to the canonical Config.TraceFilter method.
 func filterFromConfig(cfg flags.Config) globalfilter.Filter {
-	filter := cfg.GlobalFilter.Clone()
-	if filter.IsActive() {
-		return filter
-	}
-	if cfg.CommFilter != "" {
-		filter.Comm = &globalfilter.StringFilter{Pattern: cfg.CommFilter}
-	}
-	if cfg.PathFilter != "" {
-		filter.File = &globalfilter.StringFilter{Pattern: cfg.PathFilter}
-	}
-	if cfg.PidFilter > 0 {
-		filter.PID = eqNumericFilter(cfg.PidFilter)
-	}
-	if cfg.TidFilter > 0 {
-		filter.TID = eqNumericFilter(cfg.TidFilter)
-	}
-	return filter
-}
-
-func eqNumericFilter(value int) *globalfilter.NumericFilter {
-	if value <= 0 {
-		return nil
-	}
-	return &globalfilter.NumericFilter{Op: globalfilter.OpEq, Value: int64(value)}
+	return cfg.TraceFilter()
 }
 
 func (m *Model) setProcessFilters(pid, tid int) {
@@ -887,10 +838,12 @@ func (m *Model) setProcessFilters(pid, tid int) {
 
 func (m *Model) setGlobalFilter(filter globalfilter.Filter) {
 	m.globalFilter = filter.Clone()
-	pid, _ := eqNumericFilterValue(m.globalFilter.PID)
-	tid, _ := eqNumericFilterValue(m.globalFilter.TID)
-	m.pidFilter = pid
-	m.tidFilter = tid
+	// EqValue returns (0, false) when no equality filter is set;
+	// selectedPIDFilter maps non-positive values to -1 ("no filter").
+	pid, _ := m.globalFilter.PID.EqValue()
+	tid, _ := m.globalFilter.TID.EqValue()
+	m.pidFilter = selectedPIDFilter(pid)
+	m.tidFilter = selectedPIDFilter(tid)
 	m.syncDashboardFilterState()
 }
 
@@ -903,8 +856,8 @@ func (m *Model) syncDashboardFilterState() {
 
 func applyProcessFilters(filter globalfilter.Filter, pid, tid int) globalfilter.Filter {
 	out := filter.Clone()
-	out.PID = eqNumericFilter(pid)
-	out.TID = eqNumericFilter(tid)
+	out.PID = globalfilter.NewEqFilter(int64(pid))
+	out.TID = globalfilter.NewEqFilter(int64(tid))
 	return out
 }
 
@@ -950,13 +903,6 @@ func (m Model) undoGlobalFilter() (tea.Model, tea.Cmd) {
 	return m, tea.Batch(m.spin.Tick, m.beginTraceCmd())
 }
 
-func eqNumericFilterValue(filter *globalfilter.NumericFilter) (int, bool) {
-	if filter == nil || filter.Op != globalfilter.OpEq || filter.Value <= 0 {
-		return -1, false
-	}
-	return int(filter.Value), true
-}
-
 func globalFilterActionLabel(prev, next globalfilter.Filter, action string) string {
 	if strings.TrimSpace(action) != "" {
 		return action
@@ -1196,16 +1142,9 @@ func defaultParquetRecordingFilename() string {
 	return fmt.Sprintf("ior-recording-%s.parquet", time.Now().Format("20060102-150405"))
 }
 
+// tuiParquetMetadata delegates to the canonical parquet.NewFileMetadata.
 func tuiParquetMetadata() parquet.FileMetadata {
-	meta := parquet.FileMetadata{
-		StartedAtUnixNano: uint64(time.Now().UnixNano()),
-		Mode:              "tui",
-		IORVersion:        flags.Version,
-	}
-	if hostname, err := os.Hostname(); err == nil {
-		meta.Hostname = hostname
-	}
-	return meta
+	return parquet.NewFileMetadata("tui")
 }
 
 func shortenRecordingPath(path string) string {
diff --git a/internal/tui/tui_test.go b/internal/tui/tui_test.go
index 6ce16e6..7f43961 100644
--- a/internal/tui/tui_test.go
+++ b/internal/tui/tui_test.go
@@ -88,8 +88,6 @@ func TestRuntimeBindingsContextRoundTrip(t *testing.T) {
 }
 
 func TestPidSelectedTransitionsToDashboardAndSetsPIDFilter(t *testing.T) {
-	flags.SetPidFilter(-1)
-	flags.SetTidFilter(99)
 	m := NewModel(-1, func(context.Context) error { return nil })
 
 	next, cmd := m.Update(PidSelectedMsg{Pid: 42})
@@ -113,7 +111,6 @@ func TestPidSelectedTransitionsToDashboardAndSetsPIDFilter(t *testing.T) {
 }
 
 func TestInitialPIDSkipsPickerAndStartsTracing(t *testing.T) {
-	flags.SetPidFilter(-1)
 	m := NewModel(7, func(context.Context) error { return nil })
 
 	if m.screen != ScreenDashboard {
@@ -127,7 +124,6 @@ func TestInitialPIDSkipsPickerAndStartsTracing(t *testing.T) {
 }
 
 func TestPidSelectedAllSetsNoFilter(t *testing.T) {
-	flags.SetPidFilter(999)
 	m := NewModel(-1, func(context.Context) error { return nil })
 
 	next, _ := m.Update(PidSelectedMsg{Pid: 0})
@@ -696,9 +692,6 @@ func TestTracingStartedAppliesViewportWhenModelSizeIsUnset(t *testing.T) {
 }
 
 func TestExportKeyOpensModalOnDashboard(t *testing.T) {
-	flags.SetTUIExportEnable(true)
-	t.Cleanup(func() { flags.SetTUIExportEnable(true) })
-
 	m := NewModel(-1, func(context.Context) error { return nil })
 	m.screen = ScreenDashboard
 	m.attaching = false
@@ -1118,8 +1111,6 @@ func TestPidSelectedClearsPersistentStreamBuffer(t *testing.T) {
 }
 
 func TestSelectTIDKeyReturnsToPickerWhenPIDFilterIsAll(t *testing.T) {
-	flags.SetPidFilter(-1)
-	flags.SetTidFilter(-1)
 	m := NewModel(-1, func(context.Context) error { return nil })
 	m.screen = ScreenDashboard
 	m.attaching = false
@@ -1146,9 +1137,9 @@ func TestSelectTIDKeyReturnsToPickerWhenPIDFilterIsAll(t *testing.T) {
 }
 
 func TestSelectTIDKeyReturnsToPickerWhenSinglePIDSelected(t *testing.T) {
-	flags.SetPidFilter(1234)
-	flags.SetTidFilter(-1)
-	m := NewModel(-1, func(context.Context) error { return nil })
+	cfg := flags.NewFlags()
+	cfg.PidFilter = 1234
+	m := NewModelWithConfig(cfg, -1, func(context.Context) error { return nil })
 	m.screen = ScreenDashboard
 	m.attaching = false
 	m.width = 120
@@ -1174,9 +1165,9 @@ func TestSelectTIDKeyReturnsToPickerWhenSinglePIDSelected(t *testing.T) {
 }
 
 func TestTidSelectedTransitionsToDashboardAndSetsTIDFilter(t *testing.T) {
-	flags.SetPidFilter(2222)
-	flags.SetTidFilter(-1)
-	m := NewModel(-1, func(context.Context) error { return nil })
+	cfg := flags.NewFlags()
+	cfg.PidFilter = 2222
+	m := NewModelWithConfig(cfg, -1, func(context.Context) error { return nil })
 
 	next, cmd := m.Update(TidSelectedMsg{Pid: 0, Tid: 3333})
 	if cmd == nil {
@@ -1198,8 +1189,6 @@ func TestTidSelectedTransitionsToDashboardAndSetsTIDFilter(t *testing.T) {
 }
 
 func TestTidSelectedFromAllPIDModeSetsOwningPID(t *testing.T) {
-	flags.SetPidFilter(-1)
-	flags.SetTidFilter(-1)
 	m := NewModel(-1, func(context.Context) error { return nil })
 
 	next, cmd := m.Update(TidSelectedMsg{Pid: 4444, Tid: 5555})
@@ -1219,10 +1208,9 @@ func TestTidSelectedFromAllPIDModeSetsOwningPID(t *testing.T) {
 }
 
 func TestExportKeyIgnoredWhenExportDisabled(t *testing.T) {
-	flags.SetTUIExportEnable(false)
-	t.Cleanup(func() { flags.SetTUIExportEnable(true) })
-
-	m := NewModel(-1, func(context.Context) error { return nil })
+	cfg := flags.NewFlags()
+	cfg.TUIExportEnable = false
+	m := NewModelWithConfig(cfg, -1, func(context.Context) error { return nil })
 	m.screen = ScreenDashboard
 	m.attaching = false
 
@@ -1234,8 +1222,6 @@ func TestExportKeyIgnoredWhenExportDisabled(t *testing.T) {
 }
 
 func TestStreamFilterModalConsumesEKeyInsteadOfOpeningExport(t *testing.T) {
-	flags.SetTUIExportEnable(true)
-	t.Cleanup(func() { flags.SetTUIExportEnable(true) })
 
 	m := NewModel(-1, func(context.Context) error { return nil })
 	m.screen = ScreenDashboard
@@ -1925,8 +1911,6 @@ func advanceFlameSelection(t *testing.T, m *Model) string {
 }
 
 func TestQuestionMarkDoesNotBreakExportModalInput(t *testing.T) {
-	flags.SetTUIExportEnable(true)
-	t.Cleanup(func() { flags.SetTUIExportEnable(true) })
 
 	m := NewModel(-1, func(context.Context) error { return nil })
 	m.screen = ScreenDashboard
@@ -1951,10 +1935,9 @@ func TestQuestionMarkDoesNotBreakExportModalInput(t *testing.T) {
 }
 
 func TestStatusBarHidesExportBindingWhenExportDisabled(t *testing.T) {
-	flags.SetTUIExportEnable(false)
-	t.Cleanup(func() { flags.SetTUIExportEnable(true) })
-
-	m := NewModel(-1, func(context.Context) error { return nil })
+	cfg := flags.NewFlags()
+	cfg.TUIExportEnable = false
+	m := NewModelWithConfig(cfg, -1, func(context.Context) error { return nil })
 	m.screen = ScreenDashboard
 	m.width = 100
 	m.height = 30