feat(router): surface bandit knobs as [router.bandit] config

Four hardcoded constants in the selector and feedback tracker are now
user-tunable via [router.bandit]:

- quality_alpha    (EMA smoothing, default 0.3)
- min_observations (samples before observed overrides heuristic, default 3)
- observed_weight  (observed/heuristic blend ratio, default 0.7)
- strength_bonus   (quality bonus for Strengths-tagged arms, default 0.15)

Each field treats 0 as 'use default', so an empty TOML block is
byte-identical to pre-config behaviour. BanditParams is plumbed via
router.Config{Bandit: ...} and resolveBanditParams() centralises the
fallback so every call site shares the same defaults.

QualityTracker, scoreArm, bestScored, and selectBest signatures now
take the configured values directly rather than reaching for package-
level constants. Tests updated to pass BanditParams{} (defaults) or
explicit overrides where they validate the new tuning paths.

Tracks item #3 from the 'Bandit selector — design decisions deferred'
TODO entry — ships independently of the EMA vs SLM strategic decision.

cmd/gnoma/main.go

@@ -397,7 +397,17 @@ func main() {
 
 	// Create router and register the provider as a single arm
 	// (M4 foundation: one provider from CLI. Multi-provider routing comes with config.)
-	rtr := router.New(router.Config{Logger: logger})
+	// BanditParams come from [router.bandit] config keys; zero values
+	// resolve to built-in defaults inside the router package.
+	rtr := router.New(router.Config{
+		Logger: logger,
+		Bandit: router.BanditParams{
+			QualityAlpha:    cfg.Router.Bandit.QualityAlpha,
+			MinObservations: cfg.Router.Bandit.MinObservations,
+			ObservedWeight:  cfg.Router.Bandit.ObservedWeight,
+			StrengthBonus:   cfg.Router.Bandit.StrengthBonus,
+		},
+	})
 
 	// Apply the prefer-routing-policy from config (default: auto).
 	// Invalid values are rejected here with an actionable error rather

internal/config/config.go

@@ -157,6 +157,40 @@ type RouterSection struct {
 	// and incognito take priority over this knob. See
 	// docs/superpowers/plans/2026-05-23-prefer-routing-policy.md.
 	Prefer string `toml:"prefer"`
+
+	// Bandit exposes the selector's tuning knobs. Defaults preserve
+	// previous hard-coded behaviour exactly; only set these when you
+	// need to tune the EMA quality tracker for an unusual workload.
+	Bandit BanditSection `toml:"bandit"`
+}
+
+// BanditSection holds the scoring knobs for the EMA quality tracker
+// and the score blend used by the selector. Each field has a sentinel
+// zero value that means "use the built-in default" so an empty TOML
+// block is byte-identical to pre-config behaviour. See
+// internal/router/feedback.go and internal/router/selector.go for the
+// formulas these knobs feed into.
+type BanditSection struct {
+	// QualityAlpha is the EMA smoothing factor for arm-quality
+	// observations. Larger values weight recent observations more.
+	// Default: 0.3 (~3-sample memory). 0.0 here means "use default".
+	QualityAlpha float64 `toml:"quality_alpha"`
+
+	// MinObservations is the minimum number of samples required
+	// before observed EMA overrides the heuristic fallback. Default:
+	// 3. 0 here means "use default".
+	MinObservations int `toml:"min_observations"`
+
+	// ObservedWeight is the weight of the observed EMA in the
+	// observed/heuristic blend inside scoreArm: the final quality is
+	// `observed*W + heuristic*(1-W)`. Default: 0.7. 0.0 here means
+	// "use default".
+	ObservedWeight float64 `toml:"observed_weight"`
+
+	// StrengthBonus is the quality bonus added when an arm declares
+	// the current task type in its Strengths list. Default: 0.15.
+	// 0.0 here means "use default".
+	StrengthBonus float64 `toml:"strength_bonus"`
 }
 
 // MCPServerConfig defines an MCP server to start and connect to.

internal/router/bench_test.go

@@ -57,12 +57,12 @@ func benchTasks() []Task {
 func BenchmarkSelectBest(b *testing.B) {
 	arms := benchArms()
 	tasks := benchTasks()
-	qt := NewQualityTracker()
+	qt := NewQualityTracker(0, 0)
 
 	b.ResetTimer()
 	for b.Loop() {
 		for _, task := range tasks {
-			selectBest(qt, arms, task, PreferAuto)
+			selectBest(qt, BanditParams{}, arms, task, PreferAuto)
 		}
 	}
 }
@@ -99,13 +99,13 @@ func BenchmarkRouterSelect(b *testing.B) {
 
 func BenchmarkScoreArm(b *testing.B) {
 	arms := benchArms()
-	qt := NewQualityTracker()
+	qt := NewQualityTracker(0, 0)
 	task := Task{Type: TaskGeneration, Priority: PriorityNormal, EstimatedTokens: 2000, RequiresTools: true, ComplexityScore: 0.5}
 
 	b.ResetTimer()
 	for b.Loop() {
 		for _, arm := range arms {
-			scoreArm(qt, arm, task)
+			scoreArm(qt, BanditParams{}, arm, task)
 		}
 	}
 }

internal/router/feedback.go

@@ -2,9 +2,15 @@ package router
 
 import "sync"
 
+// Built-in defaults for the bandit knobs. Surfaced via
+// [router.bandit] config keys; see BanditParams in router.go. Kept
+// here so the QualityTracker has a sensible fallback when constructed
+// without explicit parameters (tests, ad-hoc callers).
 const (
-	qualityAlpha    = 0.3 // EMA smoothing factor (~3-sample memory)
-	minObservations = 3   // min samples before observed score overrides heuristic
+	defaultQualityAlpha    = 0.3 // EMA smoothing factor (~3-sample memory)
+	defaultMinObservations = 3   // min samples before observed score overrides heuristic
+	defaultObservedWeight  = 0.7 // weight of observed score in observed/heuristic blend
+	defaultStrengthBonus   = 0.15
 )
 
 // EMAScore tracks an exponential moving average quality score.
@@ -19,13 +25,27 @@ type QualityTracker struct {
 	mu              sync.RWMutex
 	scores          map[ArmID]map[TaskType]*EMAScore
 	classifierCount map[ClassifierSource]int
+
+	// Configurable knobs — set via NewQualityTracker. Pass 0 for any
+	// argument to keep the built-in default.
+	alpha           float64
+	minObservations int
 }
 
-// NewQualityTracker returns an empty QualityTracker.
-func NewQualityTracker() *QualityTracker {
+// NewQualityTracker returns an empty QualityTracker. Pass 0 for any
+// argument to keep the built-in default (alpha=0.3, minObs=3).
+func NewQualityTracker(alpha float64, minObs int) *QualityTracker {
+	if alpha == 0 {
+		alpha = defaultQualityAlpha
+	}
+	if minObs == 0 {
+		minObs = defaultMinObservations
+	}
 	return &QualityTracker{
 		scores:          make(map[ArmID]map[TaskType]*EMAScore),
 		classifierCount: make(map[ClassifierSource]int),
+		alpha:           alpha,
+		minObservations: minObs,
 	}
 }
 
@@ -71,7 +91,7 @@ func (qt *QualityTracker) Record(armID ArmID, taskType TaskType, success bool) {
 	if s.Count == 0 {
 		s.Value = observation
 	} else {
-		s.Value = qualityAlpha*observation + (1-qualityAlpha)*s.Value
+		s.Value = qt.alpha*observation + (1-qt.alpha)*s.Value
 	}
 	s.Count++
 }
@@ -86,7 +106,7 @@ func (qt *QualityTracker) Quality(armID ArmID, taskType TaskType) (score float64
 		return 0, false
 	}
 	s, ok := m[taskType]
-	if !ok || s.Count < minObservations {
+	if !ok || s.Count < qt.minObservations {
 		return 0, false
 	}
 	return s.Value, true

internal/router/feedback_test.go

@@ -8,7 +8,7 @@ import (
 )
 
 func TestQualityTracker_NoDataReturnsHeuristic(t *testing.T) {
-	qt := router.NewQualityTracker()
+	qt := router.NewQualityTracker(0, 0)
 	_, hasData := qt.Quality("arm:model", router.TaskGeneration)
 	if hasData {
 		t.Error("expected no data for unobserved arm")
@@ -16,7 +16,7 @@ func TestQualityTracker_NoDataReturnsHeuristic(t *testing.T) {
 }
 
 func TestQualityTracker_RecordUpdatesEMA(t *testing.T) {
-	qt := router.NewQualityTracker()
+	qt := router.NewQualityTracker(0, 0)
 	for i := 0; i < 3; i++ {
 		qt.Record("arm:model", router.TaskGeneration, true)
 	}
@@ -30,7 +30,7 @@ func TestQualityTracker_RecordUpdatesEMA(t *testing.T) {
 }
 
 func TestQualityTracker_AllFailuresLowScore(t *testing.T) {
-	qt := router.NewQualityTracker()
+	qt := router.NewQualityTracker(0, 0)
 	for i := 0; i < 5; i++ {
 		qt.Record("arm:model", router.TaskDebug, false)
 	}
@@ -41,7 +41,7 @@ func TestQualityTracker_AllFailuresLowScore(t *testing.T) {
 }
 
 func TestQualityTracker_ConcurrentSafe(t *testing.T) {
-	qt := router.NewQualityTracker()
+	qt := router.NewQualityTracker(0, 0)
 	done := make(chan struct{})
 	for i := 0; i < 10; i++ {
 		go func(success bool) {
@@ -113,3 +113,45 @@ func TestQualityTracker_InsufficientDataFallsBackToHeuristic(t *testing.T) {
 	}
 	decision.Rollback()
 }
+
+func TestQualityTracker_CustomAlphaShortensMemory(t *testing.T) {
+	// alpha=0.9 weights the latest sample heavily; after a single
+	// failure the score should drop further than with the default 0.3.
+	fast := router.NewQualityTracker(0.9, 0)
+	slow := router.NewQualityTracker(0.0, 0) // 0 → default 0.3
+
+	for _, qt := range []*router.QualityTracker{fast, slow} {
+		// Build up history at the high end with 5 successes.
+		for i := 0; i < 5; i++ {
+			qt.Record("arm:m", router.TaskGeneration, true)
+		}
+		// One failure.
+		qt.Record("arm:m", router.TaskGeneration, false)
+	}
+
+	fastScore, _ := fast.Quality("arm:m", router.TaskGeneration)
+	slowScore, _ := slow.Quality("arm:m", router.TaskGeneration)
+
+	if !(fastScore < slowScore) {
+		t.Errorf("expected fast alpha (0.9) to drop quality faster than default (0.3): fast=%f slow=%f", fastScore, slowScore)
+	}
+}
+
+func TestQualityTracker_CustomMinObservationsGatesScore(t *testing.T) {
+	// minObs=10 means Quality should return hasData=false until 10
+	// observations are recorded, even though the default would say
+	// "yes" after 3.
+	qt := router.NewQualityTracker(0, 10)
+	for i := 0; i < 5; i++ {
+		qt.Record("arm:m", router.TaskGeneration, true)
+	}
+	if _, hasData := qt.Quality("arm:m", router.TaskGeneration); hasData {
+		t.Error("expected hasData=false at 5 observations with minObs=10")
+	}
+	for i := 0; i < 5; i++ {
+		qt.Record("arm:m", router.TaskGeneration, true)
+	}
+	if _, hasData := qt.Quality("arm:m", router.TaskGeneration); !hasData {
+		t.Error("expected hasData=true after 10 observations with minObs=10")
+	}
+}

internal/router/quality_json_test.go

@@ -8,7 +8,7 @@ import (
 )
 
 func TestQualityTracker_SnapshotRestore_RoundTrip(t *testing.T) {
-	qt := router.NewQualityTracker()
+	qt := router.NewQualityTracker(0, 0)
 	// Record some outcomes
 	qt.Record("anthropic/claude-3-5-sonnet", router.TaskGeneration, true)
 	qt.Record("anthropic/claude-3-5-sonnet", router.TaskGeneration, true)
@@ -33,7 +33,7 @@ func TestQualityTracker_SnapshotRestore_RoundTrip(t *testing.T) {
 	}
 
 	// Restore into a fresh tracker
-	qt2 := router.NewQualityTracker()
+	qt2 := router.NewQualityTracker(0, 0)
 	qt2.Restore(restored)
 
 	// After restore, Quality() should return data (Count >= minObservations=3)
@@ -47,7 +47,7 @@ func TestQualityTracker_SnapshotRestore_RoundTrip(t *testing.T) {
 }
 
 func TestQualityTracker_Snapshot_Empty(t *testing.T) {
-	qt := router.NewQualityTracker()
+	qt := router.NewQualityTracker(0, 0)
 	snap := qt.Snapshot()
 	if snap.Scores == nil {
 		t.Error("scores map should be initialized (not nil)")
@@ -58,7 +58,7 @@ func TestQualityTracker_Snapshot_Empty(t *testing.T) {
 }
 
 func TestQualityTracker_ClassifierCounts_RecordAndSnapshot(t *testing.T) {
-	qt := router.NewQualityTracker()
+	qt := router.NewQualityTracker(0, 0)
 	qt.RecordClassifier(router.ClassifierHeuristic)
 	qt.RecordClassifier(router.ClassifierSLM)
 	qt.RecordClassifier(router.ClassifierSLM)
@@ -92,7 +92,7 @@ func TestQualityTracker_ClassifierCounts_RecordAndSnapshot(t *testing.T) {
 	if err := json.Unmarshal(data, &restored); err != nil {
 		t.Fatal(err)
 	}
-	qt2 := router.NewQualityTracker()
+	qt2 := router.NewQualityTracker(0, 0)
 	qt2.Restore(restored)
 	if qt2.ClassifierCounts()[router.ClassifierSLM] != 2 {
 		t.Errorf("restored slm count = %d, want 2", qt2.ClassifierCounts()[router.ClassifierSLM])
@@ -107,7 +107,7 @@ func TestQualityTracker_Restore_BackCompat_NoClassifierCounts(t *testing.T) {
 	if err := json.Unmarshal(legacy, &snap); err != nil {
 		t.Fatal(err)
 	}
-	qt := router.NewQualityTracker()
+	qt := router.NewQualityTracker(0, 0)
 	qt.Restore(snap)
 	if qt.ClassifierCounts() == nil {
 		t.Error("ClassifierCounts() must return a non-nil map after restoring old snapshot")
@@ -122,7 +122,7 @@ func TestQualityTracker_Restore_BackCompat_NoClassifierCounts(t *testing.T) {
 }
 
 func TestQualityTracker_Restore_Replaces(t *testing.T) {
-	qt := router.NewQualityTracker()
+	qt := router.NewQualityTracker(0, 0)
 	qt.Record("arm-a", router.TaskDebug, true)
 	qt.Record("arm-a", router.TaskDebug, true)
 	qt.Record("arm-a", router.TaskDebug, true)

internal/router/router.go

@@ -27,6 +27,7 @@ type Router struct {
 	preferPolicy PreferPolicy
 
 	quality *QualityTracker
+	bandit  BanditParams
 }
 
 // PreferPolicy biases the scoring step toward local or cloud arms.
@@ -77,6 +78,41 @@ func (p PreferPolicy) String() string {
 
 type Config struct {
 	Logger *slog.Logger
+	// Bandit tunes the selector's scoring knobs. Pass a zero value to
+	// keep all pre-config behaviour byte-identical; set individual
+	// fields to override the corresponding default.
+	Bandit BanditParams
+}
+
+// BanditParams controls the EMA quality tracker and score blend used
+// by the selector. Each field has a "use default" sentinel (0 for
+// floats and ints) so a zero-valued BanditParams is byte-identical to
+// the pre-config hardcoded constants. Defaults are defined in
+// resolveBanditParams below.
+type BanditParams struct {
+	QualityAlpha    float64
+	MinObservations int
+	ObservedWeight  float64
+	StrengthBonus   float64
+}
+
+// resolveBanditParams fills in the built-in defaults for any field
+// left at its zero value. Centralised so the same defaults apply
+// across NewQualityTracker, scoreArm, and any future caller.
+func resolveBanditParams(p BanditParams) BanditParams {
+	if p.QualityAlpha == 0 {
+		p.QualityAlpha = defaultQualityAlpha
+	}
+	if p.MinObservations == 0 {
+		p.MinObservations = defaultMinObservations
+	}
+	if p.ObservedWeight == 0 {
+		p.ObservedWeight = defaultObservedWeight
+	}
+	if p.StrengthBonus == 0 {
+		p.StrengthBonus = defaultStrengthBonus
+	}
+	return p
 }
 
 func New(cfg Config) *Router {
@@ -84,10 +120,12 @@ func New(cfg Config) *Router {
 	if logger == nil {
 		logger = slog.Default()
 	}
+	params := resolveBanditParams(cfg.Bandit)
 	return &Router{
 		arms:    make(map[ArmID]*Arm),
 		logger:  logger,
-		quality: NewQualityTracker(),
+		quality: NewQualityTracker(params.QualityAlpha, params.MinObservations),
+		bandit:  params,
 	}
 }
 
@@ -172,7 +210,7 @@ func (r *Router) Select(task Task) RoutingDecision {
 	}
 
 	// Select best
-	best := selectBest(r.quality, feasible, task, r.preferPolicy)
+	best := selectBest(r.quality, r.bandit, feasible, task, r.preferPolicy)
 	if best == nil {
 		return RoutingDecision{Error: fmt.Errorf("selection failed")}
 	}

internal/router/router_test.go

@@ -262,7 +262,7 @@ func TestSelectBest_PrefersToolSupport(t *testing.T) {
 	}
 
 	task := Task{Type: TaskGeneration, RequiresTools: true, Priority: PriorityNormal}
-	best := selectBest(nil, []*Arm{withoutTools, withTools}, task, PreferAuto)
+	best := selectBest(nil, BanditParams{}, []*Arm{withoutTools, withTools}, task, PreferAuto)
 
 	if best.ID != "a/with-tools" {
 		t.Errorf("should prefer arm with tool support, got %s", best.ID)
@@ -282,7 +282,7 @@ func TestSelectBest_PrefersThinkingForPlanning(t *testing.T) {
 	}
 
 	task := Task{Type: TaskPlanning, RequiresTools: true, Priority: PriorityNormal, EstimatedTokens: 5000}
-	best := selectBest(nil, []*Arm{noThinking, thinking}, task, PreferAuto)
+	best := selectBest(nil, BanditParams{}, []*Arm{noThinking, thinking}, task, PreferAuto)
 
 	if best.ID != "a/thinking" {
 		t.Errorf("should prefer thinking model for planning, got %s", best.ID)
@@ -625,7 +625,7 @@ func TestSelectBest_SmallArmWinsTrivialTask(t *testing.T) {
 		Capabilities:  provider.Capabilities{ToolUse: false},
 	}
 	task := Task{Type: TaskExplain, ComplexityScore: 0.05, RequiresTools: false}
-	got := selectBest(nil, []*Arm{cliArm, smallArm}, task, PreferAuto)
+	got := selectBest(nil, BanditParams{}, []*Arm{cliArm, smallArm}, task, PreferAuto)
 	if got != smallArm {
 		t.Errorf("selectBest = %v, want smallArm", got)
 	}
@@ -647,7 +647,7 @@ func TestSelectBest_CLIAgentWinsComplexTask(t *testing.T) {
 		Capabilities:  provider.Capabilities{ToolUse: false},
 	}
 	task := Task{Type: TaskRefactor, ComplexityScore: 0.7, RequiresTools: true}
-	got := selectBest(nil, []*Arm{cliArm, smallArm}, task, PreferAuto)
+	got := selectBest(nil, BanditParams{}, []*Arm{cliArm, smallArm}, task, PreferAuto)
 	if got != cliArm {
 		t.Errorf("selectBest = %v, want cliArm", got)
 	}
@@ -672,21 +672,21 @@ func TestSelectBest_TierPreference(t *testing.T) {
 	task := Task{Type: TaskGeneration, Priority: PriorityNormal, EstimatedTokens: 1000}
 
 	t.Run("CLI beats local and API", func(t *testing.T) {
-		best := selectBest(nil, []*Arm{apiArm, localArm, cliArm}, task, PreferAuto)
+		best := selectBest(nil, BanditParams{}, []*Arm{apiArm, localArm, cliArm}, task, PreferAuto)
 		if best.ID != "subprocess/claude" {
 			t.Errorf("want subprocess/claude (tier 0), got %s", best.ID)
 		}
 	})
 
 	t.Run("local beats API when no CLI", func(t *testing.T) {
-		best := selectBest(nil, []*Arm{apiArm, localArm}, task, PreferAuto)
+		best := selectBest(nil, BanditParams{}, []*Arm{apiArm, localArm}, task, PreferAuto)
 		if best.ID != "ollama/llama3" {
 			t.Errorf("want ollama/llama3 (tier 1), got %s", best.ID)
 		}
 	})
 
 	t.Run("API selected when only option", func(t *testing.T) {
-		best := selectBest(nil, []*Arm{apiArm}, task, PreferAuto)
+		best := selectBest(nil, BanditParams{}, []*Arm{apiArm}, task, PreferAuto)
 		if best == nil || best.ID != "mistral/mistral-large" {
 			t.Errorf("want mistral/mistral-large (tier 2), got %v", best)
 		}

internal/router/selector.go

@@ -98,7 +98,7 @@ func armBaseTier(arm *Arm, task Task) int {
 //
 // Step 2 (fallback): walk tiers low→high. Within a tier, highest-scoring
 // arm wins.
-func selectBest(qt *QualityTracker, arms []*Arm, task Task, prefer PreferPolicy) *Arm {
+func selectBest(qt *QualityTracker, params BanditParams, arms []*Arm, task Task, prefer PreferPolicy) *Arm {
 	if len(arms) == 0 {
 		return nil
 	}
@@ -110,7 +110,7 @@ func selectBest(qt *QualityTracker, arms []*Arm, task Task, prefer PreferPolicy)
 		}
 	}
 	if len(promoted) > 0 {
-		return bestScored(qt, promoted, task, prefer)
+		return bestScored(qt, params, promoted, task, prefer)
 	}
 
 	// Walk tiers low→high. armTier returns up to 5 when prefer is set
@@ -124,18 +124,18 @@ func selectBest(qt *QualityTracker, arms []*Arm, task Task, prefer PreferPolicy)
 			}
 		}
 		if len(inTier) > 0 {
-			return bestScored(qt, inTier, task, prefer)
+			return bestScored(qt, params, inTier, task, prefer)
 		}
 	}
 	return nil
 }
 
 // bestScored returns the highest-scoring arm within a set.
-func bestScored(qt *QualityTracker, arms []*Arm, task Task, prefer PreferPolicy) *Arm {
+func bestScored(qt *QualityTracker, params BanditParams, arms []*Arm, task Task, prefer PreferPolicy) *Arm {
 	var best *Arm
 	bestScore := math.Inf(-1)
 	for _, arm := range arms {
-		score := scoreArm(qt, arm, task) * policyMultiplier(arm, prefer)
+		score := scoreArm(qt, params, arm, task) * policyMultiplier(arm, prefer)
 		if score > bestScore {
 			bestScore = score
 			best = arm
@@ -172,13 +172,12 @@ func policyMultiplier(arm *Arm, p PreferPolicy) float64 {
 	}
 }
 
-// strengthScoreBonus is added to quality when an arm's Strengths list
-// matches the incoming task type. Tunable in one place.
-const strengthScoreBonus = 0.15
-
 // scoreArm computes a quality/cost score for an arm.
 // When the quality tracker has sufficient observations, blends observed EMA
-// (70%) with heuristic (30%). Falls back to pure heuristic otherwise.
+// (default 70%) with heuristic (default 30%). Falls back to pure heuristic
+// otherwise. The blend ratio and strength bonus are tunable via
+// BanditParams (config: [router.bandit]); a zero-valued params falls back
+// to the built-in defaults.
 //
 // Strengths add a fixed bonus to quality when matching task.Type. CostWeight
 // dampens the cost penalty linearly:
@@ -189,16 +188,17 @@ const strengthScoreBonus = 0.15
 // the original effectiveCost == cost. With CostWeight=0 cost is fully
 // ignored (effectiveCost = 1.0). Local arms with sub-1 raw costs are not
 // amplified by fractional weights (the linear formula stays monotone).
-func scoreArm(qt *QualityTracker, arm *Arm, task Task) float64 {
+func scoreArm(qt *QualityTracker, params BanditParams, arm *Arm, task Task) float64 {
+	params = resolveBanditParams(params)
 	hq := heuristicQuality(arm, task)
 	quality := hq
 	if qt != nil {
 		if observed, hasData := qt.Quality(arm.ID, task.Type); hasData {
-			quality = 0.7*observed + 0.3*hq
+			quality = params.ObservedWeight*observed + (1-params.ObservedWeight)*hq
 		}
 	}
 	if arm.HasStrength(task.Type) {
-		quality += strengthScoreBonus
+		quality += params.StrengthBonus
 	}
 	value := task.ValueScore()
 	rawCost := effectiveCost(arm, task)

internal/router/strengths_test.go

@@ -65,17 +65,17 @@ func TestScoreArm_CostWeightAffectsArmComparison(t *testing.T) {
 
 	// CostWeight=1.0: cost dominates, cheap arm wins.
 	cheap.CostWeight, expensive.CostWeight = 1.0, 1.0
-	if scoreArm(nil, cheap, task) <= scoreArm(nil, expensive, task) {
+	if scoreArm(nil, BanditParams{}, cheap, task) <= scoreArm(nil, BanditParams{}, expensive, task) {
 		t.Errorf("CostWeight=1.0: cheap arm should beat expensive arm; cheap=%v expensive=%v",
-			scoreArm(nil, cheap, task), scoreArm(nil, expensive, task))
+			scoreArm(nil, BanditParams{}, cheap, task), scoreArm(nil, BanditParams{}, expensive, task))
 	}
 
 	// CostWeight=0.0: cost ignored, quality alone decides → expensive (better
 	// context window) wins.
 	cheap.CostWeight, expensive.CostWeight = 0.001, 0.001
-	if scoreArm(nil, expensive, task) <= scoreArm(nil, cheap, task) {
+	if scoreArm(nil, BanditParams{}, expensive, task) <= scoreArm(nil, BanditParams{}, cheap, task) {
 		t.Errorf("CostWeight~0: higher-quality expensive arm should beat cheap arm; expensive=%v cheap=%v",
-			scoreArm(nil, expensive, task), scoreArm(nil, cheap, task))
+			scoreArm(nil, BanditParams{}, expensive, task), scoreArm(nil, BanditParams{}, cheap, task))
 	}
 }
 
@@ -140,8 +140,8 @@ func TestScoreArm_StrengthBonus(t *testing.T) {
 	}
 	task := Task{Type: TaskSecurityReview, EstimatedTokens: 5000, RequiresTools: true, Priority: PriorityNormal}
 
-	a := scoreArm(nil, withoutStrength, task)
-	b := scoreArm(nil, withStrength, task)
+	a := scoreArm(nil, BanditParams{}, withoutStrength, task)
+	b := scoreArm(nil, BanditParams{}, withStrength, task)
 	if !(b > a) {
 		t.Errorf("strength-tagged arm score (%v) should exceed plain arm score (%v)", b, a)
 	}
@@ -160,8 +160,8 @@ func TestScoreArm_StrengthBonusDoesNotApplyToOtherTasks(t *testing.T) {
 	}
 	task := Task{Type: TaskDebug, EstimatedTokens: 5000, RequiresTools: true, Priority: PriorityNormal}
 
-	a := scoreArm(nil, plain, task)
-	b := scoreArm(nil, tagged, task)
+	a := scoreArm(nil, BanditParams{}, plain, task)
+	b := scoreArm(nil, BanditParams{}, tagged, task)
 	if math.Abs(a-b) > 1e-9 {
 		t.Errorf("non-matching task should ignore Strengths: plain=%v tagged=%v", a, b)
 	}
@@ -184,7 +184,7 @@ func TestSelectBest_StrengthPromotedArmBeatsCLIAgent(t *testing.T) {
 	}
 
 	task := Task{Type: TaskSecurityReview, EstimatedTokens: 5000, RequiresTools: true, Priority: PriorityNormal}
-	got := selectBest(nil, []*Arm{cliAgent, opus}, task, PreferAuto)
+	got := selectBest(nil, BanditParams{}, []*Arm{cliAgent, opus}, task, PreferAuto)
 	if got == nil {
 		t.Fatal("selectBest returned nil")
 	}
@@ -208,7 +208,7 @@ func TestSelectBest_EmptyStrengthsPreservesTierOrder(t *testing.T) {
 	}
 
 	task := Task{Type: TaskSecurityReview, EstimatedTokens: 5000, RequiresTools: true, Priority: PriorityNormal}
-	got := selectBest(nil, []*Arm{cliAgent, opus}, task, PreferAuto)
+	got := selectBest(nil, BanditParams{}, []*Arm{cliAgent, opus}, task, PreferAuto)
 	if got.ID != cliAgent.ID {
 		t.Errorf("without Strengths, CLI-agent tier-1 should win; got %s", got.ID)
 	}
@@ -327,7 +327,7 @@ func TestSelectBest_MultiplePromotedArmsBestQualityWins(t *testing.T) {
 		Strengths:    []TaskType{TaskSecurityReview},
 	}
 
-	qt := NewQualityTracker()
+	qt := NewQualityTracker(0, 0)
 	// armB has consistently succeeded — minObservations=3 is enough to flip
 	// the score blend.
 	for i := 0; i < 5; i++ {
@@ -339,7 +339,7 @@ func TestSelectBest_MultiplePromotedArmsBestQualityWins(t *testing.T) {
 	}
 
 	task := Task{Type: TaskSecurityReview, EstimatedTokens: 5000, RequiresTools: true, Priority: PriorityNormal}
-	got := selectBest(qt, []*Arm{armA, armB}, task, PreferAuto)
+	got := selectBest(qt, BanditParams{}, []*Arm{armA, armB}, task, PreferAuto)
 	if got == nil {
 		t.Fatal("selectBest returned nil")
 	}