refactor(ratelimit): remove in-memory per-window token tracking

Token counts per rate limit window are now derived in Grafana via
increase(counter[5h/168h]) on the existing cumulative OTel counters.
Removes TokensIn/Out from Window, RecordTokens, setResetTime, and
the window_tokens observable gauges.

internal/proxy/handler.go

@@ -149,7 +149,6 @@ func handleNonStream(c *gin.Context, upstream *UpstreamClient, san *Sanitizer, p
 		telemetry.TokensInput.Add(ctx, inputTokens, tokenAttrs)
 		telemetry.TokensOutput.Add(ctx, outputTokens, tokenAttrs)
 		if tracker != nil {
-			tracker.RecordTokens(inputTokens, outputTokens)
 			tracker.UpdateFromHeaders(headers)
 		}
 
@@ -305,7 +304,6 @@ func handleStream(c *gin.Context, upstream *UpstreamClient, san *Sanitizer, pool
 		telemetry.TokensInput.Add(ctx, inputTokens, tokenAttrs)
 		telemetry.TokensOutput.Add(ctx, outputTokens, tokenAttrs)
 		if tracker != nil {
-			tracker.RecordTokens(inputTokens, outputTokens)
 			tracker.UpdateFromHeaders(resp.Header)
 		}
 	}

internal/ratelimit/tracker.go

@@ -5,7 +5,6 @@ import (
 	"net/http"
 	"strconv"
 	"sync"
-	"sync/atomic"
 	"time"
 
 	"github.com/rs/zerolog/log"
@@ -15,16 +14,12 @@ import (
 type Window struct {
 	Utilization float64   // 0-100 from API
 	ResetsAt    time.Time // when window resets
-	TokensIn    atomic.Int64
-	TokensOut   atomic.Int64
 }
 
 // Snapshot is a read-only copy of a Window's state.
 type Snapshot struct {
 	Utilization float64
 	ResetsAt    time.Time
-	TokensIn    int64
-	TokensOut   int64
 }
 
 // Tracker polls /api/oauth/usage and tracks per-window token usage.
@@ -71,7 +66,7 @@ func (t *Tracker) UpdateFromHeaders(h http.Header) {
 	}
 	if v := h.Get("Anthropic-Ratelimit-Unified-5h-Reset"); v != "" {
 		if ts, err := strconv.ParseInt(v, 10, 64); err == nil {
-			t.setResetTime(&t.fiveHour, time.Unix(ts, 0).UTC().Truncate(time.Minute), "5h")
+			t.fiveHour.ResetsAt = time.Unix(ts, 0).UTC().Truncate(time.Minute)
 		}
 	}
 	if v := h.Get("Anthropic-Ratelimit-Unified-7d-Utilization"); v != "" {
@@ -81,19 +76,11 @@ func (t *Tracker) UpdateFromHeaders(h http.Header) {
 	}
 	if v := h.Get("Anthropic-Ratelimit-Unified-7d-Reset"); v != "" {
 		if ts, err := strconv.ParseInt(v, 10, 64); err == nil {
-			t.setResetTime(&t.sevenDay, time.Unix(ts, 0).UTC().Truncate(time.Minute), "7d")
+			t.sevenDay.ResetsAt = time.Unix(ts, 0).UTC().Truncate(time.Minute)
 		}
 	}
 }
 
-// RecordTokens adds tokens to all active windows.
-func (t *Tracker) RecordTokens(inputTokens, outputTokens int64) {
-	t.fiveHour.TokensIn.Add(inputTokens)
-	t.fiveHour.TokensOut.Add(outputTokens)
-	t.sevenDay.TokensIn.Add(inputTokens)
-	t.sevenDay.TokensOut.Add(outputTokens)
-}
-
 // FiveHour returns a snapshot of the 5-hour window.
 func (t *Tracker) FiveHour() Snapshot {
 	t.mu.RLock()
@@ -101,8 +88,6 @@ func (t *Tracker) FiveHour() Snapshot {
 	return Snapshot{
 		Utilization: t.fiveHour.Utilization,
 		ResetsAt:    t.fiveHour.ResetsAt,
-		TokensIn:    t.fiveHour.TokensIn.Load(),
-		TokensOut:   t.fiveHour.TokensOut.Load(),
 	}
 }
 
@@ -113,8 +98,6 @@ func (t *Tracker) SevenDay() Snapshot {
 	return Snapshot{
 		Utilization: t.sevenDay.Utilization,
 		ResetsAt:    t.sevenDay.ResetsAt,
-		TokensIn:    t.sevenDay.TokensIn.Load(),
-		TokensOut:   t.sevenDay.TokensOut.Load(),
 	}
 }
 
@@ -151,13 +134,13 @@ func (t *Tracker) poll(ctx context.Context) {
 	defer t.mu.Unlock()
 
 	if usage.FiveHour != nil {
-		t.updateWindow(&t.fiveHour, usage.FiveHour, "5h")
+		t.updateWindow(&t.fiveHour, usage.FiveHour)
 	}
 	if usage.SevenDay != nil {
-		t.updateWindow(&t.sevenDay, usage.SevenDay, "7d")
+		t.updateWindow(&t.sevenDay, usage.SevenDay)
 	}
 	if usage.SevenDaySonnet != nil {
-		t.updateWindow(&t.sonnet, usage.SevenDaySonnet, "7d_sonnet")
+		t.updateWindow(&t.sonnet, usage.SevenDaySonnet)
 	}
 	if usage.ExtraUsage != nil {
 		t.extra = *usage.ExtraUsage
@@ -166,12 +149,8 @@ func (t *Tracker) poll(ctx context.Context) {
 	log.Debug().
 		Float64("5h_util", t.fiveHour.Utilization).
 		Time("5h_resets", t.fiveHour.ResetsAt).
-		Int64("5h_tokens_in", t.fiveHour.TokensIn.Load()).
-		Int64("5h_tokens_out", t.fiveHour.TokensOut.Load()).
 		Float64("7d_util", t.sevenDay.Utilization).
 		Time("7d_resets", t.sevenDay.ResetsAt).
-		Int64("7d_tokens_in", t.sevenDay.TokensIn.Load()).
-		Int64("7d_tokens_out", t.sevenDay.TokensOut.Load()).
 		Msg("usage poll")
 
 	// Warn on high utilization
@@ -183,7 +162,7 @@ func (t *Tracker) poll(ctx context.Context) {
 	}
 }
 
-func (t *Tracker) updateWindow(w *Window, rl *RateLimit, name string) {
+func (t *Tracker) updateWindow(w *Window, rl *RateLimit) {
 	if rl.Utilization != nil {
 		w.Utilization = *rl.Utilization
 	}
@@ -193,22 +172,7 @@ func (t *Tracker) updateWindow(w *Window, rl *RateLimit, name string) {
 			parsed, err = time.Parse(time.RFC3339, *rl.ResetsAt)
 		}
 		if err == nil {
-			t.setResetTime(w, parsed.UTC().Truncate(time.Minute), name)
+			w.ResetsAt = parsed.UTC().Truncate(time.Minute)
 		}
 	}
 }
-
-func (t *Tracker) setResetTime(w *Window, newReset time.Time, name string) {
-	if !w.ResetsAt.IsZero() && newReset != w.ResetsAt {
-		log.Info().
-			Str("window", name).
-			Int64("prev_tokens_in", w.TokensIn.Load()).
-			Int64("prev_tokens_out", w.TokensOut.Load()).
-			Time("old_reset", w.ResetsAt).
-			Time("new_reset", newReset).
-			Msg("window reset detected")
-		w.TokensIn.Store(0)
-		w.TokensOut.Store(0)
-	}
-	w.ResetsAt = newReset
-}

internal/telemetry/metrics.go

@@ -82,21 +82,4 @@ func InitMetrics(meter metric.Meter, tracker *ratelimit.Tracker) {
 		}),
 	)
 
-	meter.Int64ObservableGauge("proxy.usage.window_tokens.input",
-		metric.WithDescription("Proxy input tokens in current window"),
-		metric.WithInt64Callback(func(_ context.Context, o metric.Int64Observer) error {
-			o.Observe(tracker.FiveHour().TokensIn, metric.WithAttributes(attr5h))
-			o.Observe(tracker.SevenDay().TokensIn, metric.WithAttributes(attr7d))
-			return nil
-		}),
-	)
-
-	meter.Int64ObservableGauge("proxy.usage.window_tokens.output",
-		metric.WithDescription("Proxy output tokens in current window"),
-		metric.WithInt64Callback(func(_ context.Context, o metric.Int64Observer) error {
-			o.Observe(tracker.FiveHour().TokensOut, metric.WithAttributes(attr5h))
-			o.Observe(tracker.SevenDay().TokensOut, metric.WithAttributes(attr7d))
-			return nil
-		}),
-	)
 }