[management, proxy] Add prompt-cache token and cost accounting to agent network usage (#6900)

Co-authored-by: braginini <bangvalo@gmail.com>
2026-10-08 22:49:10 +02:00 · 2026-07-26 21:42:41 +02:00
parent 1e5b0a5c89
commit 4f6247b5c3
29 changed files with 1582 additions and 170 deletions
@@ -18,21 +18,26 @@ import (
 // contract between the proxy and management; management flattens them into
 // queryable columns. Keep in sync with the proxy side.
 const (
-	metaKeyProvider           = "llm.provider"
-	metaKeyModel              = "llm.model"
-	metaKeyResolvedProviderID = "llm.resolved_provider_id"
-	metaKeySelectedPolicyID   = "llm.selected_policy_id"
-	metaKeyPolicyDecision     = "llm_policy.decision"
-	metaKeyPolicyReason       = "llm_policy.reason"
-	metaKeyInputTokens        = "llm.input_tokens"  //nolint:gosec // metadata key name, not a credential
-	metaKeyOutputTokens       = "llm.output_tokens" //nolint:gosec // metadata key name, not a credential
-	metaKeyTotalTokens        = "llm.total_tokens"  //nolint:gosec // metadata key name, not a credential
-	metaKeyCostUSDTotal       = "cost.usd_total"
-	metaKeyStream             = "llm.stream"
-	metaKeySessionID          = "llm.session_id"
-	metaKeyAuthorisingGroups  = "llm.authorising_groups"
-	metaKeyRequestPrompt      = "llm.request_prompt"
-	metaKeyResponseCompletion = "llm.response_completion"
+	metaKeyProvider            = "llm.provider"
+	metaKeyModel               = "llm.model"
+	metaKeyResolvedProviderID  = "llm.resolved_provider_id"
+	metaKeySelectedPolicyID    = "llm.selected_policy_id"
+	metaKeyPolicyDecision      = "llm_policy.decision"
+	metaKeyPolicyReason        = "llm_policy.reason"
+	metaKeyInputTokens         = "llm.input_tokens"          //nolint:gosec // metadata key name, not a credential
+	metaKeyOutputTokens        = "llm.output_tokens"         //nolint:gosec // metadata key name, not a credential
+	metaKeyTotalTokens         = "llm.total_tokens"          //nolint:gosec // metadata key name, not a credential
+	metaKeyCachedInputTokens   = "llm.cached_input_tokens"   //nolint:gosec // metadata key name, not a credential
+	metaKeyCacheCreationTokens = "llm.cache_creation_tokens" //nolint:gosec // metadata key name, not a credential
+	metaKeyCostUSDInput        = "cost.usd_input"
+	metaKeyCostUSDCachedInput  = "cost.usd_cached_input"
+	metaKeyCostUSDCacheCreate  = "cost.usd_cache_creation"
+	metaKeyCostUSDOutput       = "cost.usd_output"
+	metaKeyStream              = "llm.stream"
+	metaKeySessionID           = "llm.session_id"
+	metaKeyAuthorisingGroups   = "llm.authorising_groups"
+	metaKeyRequestPrompt       = "llm.request_prompt"
+	metaKeyResponseCompletion  = "llm.response_completion"
 )

 // IngestAccessLog flattens the metadata-bearing reverse-proxy access-log entry
@@ -108,20 +113,25 @@ func flattenAccessLog(e *accesslogs.AccessLogEntry) (*types.AgentNetworkAccessLo
 		BytesUpload:   e.BytesUpload,
 		BytesDownload: e.BytesDownload,

-		Provider:           meta[metaKeyProvider],
-		Model:              meta[metaKeyModel],
-		SessionID:          meta[metaKeySessionID],
-		ResolvedProviderID: meta[metaKeyResolvedProviderID],
-		SelectedPolicyID:   meta[metaKeySelectedPolicyID],
-		Decision:           meta[metaKeyPolicyDecision],
-		DenyReason:         meta[metaKeyPolicyReason],
-		InputTokens:        parseMetaInt(meta, metaKeyInputTokens),
-		OutputTokens:       parseMetaInt(meta, metaKeyOutputTokens),
-		TotalTokens:        parseMetaInt(meta, metaKeyTotalTokens),
-		CostUSD:            parseMetaFloat(meta, metaKeyCostUSDTotal),
-		Stream:             parseMetaBool(meta, metaKeyStream),
-		RequestPrompt:      meta[metaKeyRequestPrompt],
-		ResponseCompletion: meta[metaKeyResponseCompletion],
+		Provider:             meta[metaKeyProvider],
+		Model:                meta[metaKeyModel],
+		SessionID:            meta[metaKeySessionID],
+		ResolvedProviderID:   meta[metaKeyResolvedProviderID],
+		SelectedPolicyID:     meta[metaKeySelectedPolicyID],
+		Decision:             meta[metaKeyPolicyDecision],
+		DenyReason:           meta[metaKeyPolicyReason],
+		InputTokens:          parseMetaInt(meta, metaKeyInputTokens),
+		OutputTokens:         parseMetaInt(meta, metaKeyOutputTokens),
+		TotalTokens:          parseMetaInt(meta, metaKeyTotalTokens),
+		CachedInputTokens:    parseMetaInt(meta, metaKeyCachedInputTokens),
+		CacheCreationTokens:  parseMetaInt(meta, metaKeyCacheCreationTokens),
+		InputCostUSD:         parseMetaFloat(meta, metaKeyCostUSDInput),
+		CachedInputCostUSD:   parseMetaFloat(meta, metaKeyCostUSDCachedInput),
+		CacheCreationCostUSD: parseMetaFloat(meta, metaKeyCostUSDCacheCreate),
+		OutputCostUSD:        parseMetaFloat(meta, metaKeyCostUSDOutput),
+		Stream:               parseMetaBool(meta, metaKeyStream),
+		RequestPrompt:        meta[metaKeyRequestPrompt],
+		ResponseCompletion:   meta[metaKeyResponseCompletion],
 	}

 	var groups []types.AgentNetworkAccessLogGroup
@@ -140,18 +150,23 @@ func flattenAccessLog(e *accesslogs.AccessLogEntry) (*types.AgentNetworkAccessLo
 // log's ID so the two correlate.
 func usageFromFlattenedLog(e *types.AgentNetworkAccessLog, groups []types.AgentNetworkAccessLogGroup) (*types.AgentNetworkUsage, []types.AgentNetworkUsageGroup) {
 	usage := &types.AgentNetworkUsage{
-		ID:                 e.ID,
-		AccountID:          e.AccountID,
-		Timestamp:          e.Timestamp,
-		UserID:             e.UserID,
-		ResolvedProviderID: e.ResolvedProviderID,
-		Provider:           e.Provider,
-		Model:              e.Model,
-		SessionID:          e.SessionID,
-		InputTokens:        e.InputTokens,
-		OutputTokens:       e.OutputTokens,
-		TotalTokens:        e.TotalTokens,
-		CostUSD:            e.CostUSD,
+		ID:                   e.ID,
+		AccountID:            e.AccountID,
+		Timestamp:            e.Timestamp,
+		UserID:               e.UserID,
+		ResolvedProviderID:   e.ResolvedProviderID,
+		Provider:             e.Provider,
+		Model:                e.Model,
+		SessionID:            e.SessionID,
+		InputTokens:          e.InputTokens,
+		OutputTokens:         e.OutputTokens,
+		TotalTokens:          e.TotalTokens,
+		CachedInputTokens:    e.CachedInputTokens,
+		CacheCreationTokens:  e.CacheCreationTokens,
+		InputCostUSD:         e.InputCostUSD,
+		CachedInputCostUSD:   e.CachedInputCostUSD,
+		CacheCreationCostUSD: e.CacheCreationCostUSD,
+		OutputCostUSD:        e.OutputCostUSD,
 	}

 	usageGroups := make([]types.AgentNetworkUsageGroup, 0, len(groups))
@@ -28,17 +28,22 @@ func newIngestTestEntry() *accesslogs.AccessLogEntry {
 		UserId:       "user-1",
 		AgentNetwork: true,
 		Metadata: map[string]string{
-			metaKeyProvider:           "openai",
-			metaKeyModel:              "gpt-5.4",
-			metaKeyResolvedProviderID: "prov-1",
-			metaKeySessionID:          "sess-1",
-			metaKeyInputTokens:        "100",
-			metaKeyOutputTokens:       "50",
-			metaKeyTotalTokens:        "150",
-			metaKeyCostUSDTotal:       "0.0123",
-			metaKeyStream:             "true",
-			metaKeyRequestPrompt:      "hello",
-			metaKeyResponseCompletion: "world",
+			metaKeyProvider:            "openai",
+			metaKeyModel:               "gpt-5.4",
+			metaKeyResolvedProviderID:  "prov-1",
+			metaKeySessionID:           "sess-1",
+			metaKeyInputTokens:         "100",
+			metaKeyOutputTokens:        "50",
+			metaKeyTotalTokens:         "1174",
+			metaKeyCachedInputTokens:   "256",
+			metaKeyCacheCreationTokens: "768",
+			metaKeyCostUSDInput:        "0.0071",
+			metaKeyCostUSDCachedInput:  "0.0009",
+			metaKeyCostUSDCacheCreate:  "0.0020",
+			metaKeyCostUSDOutput:       "0.0023",
+			metaKeyStream:              "true",
+			metaKeyRequestPrompt:       "hello",
+			metaKeyResponseCompletion:  "world",
 			// repeated id must be de-duplicated before the group rows insert.
 			metaKeyAuthorisingGroups: "grp-eng,grp-eng,grp-ops",
 		},
@@ -65,7 +70,19 @@ func TestIngestAccessLog_RealStore_LogCollectionOff(t *testing.T) {
 	require.Len(t, usage, 1, "usage row must be written even with log collection off")
 	assert.Equal(t, int64(100), usage[0].InputTokens, "input tokens must round-trip from metadata")
 	assert.Equal(t, int64(50), usage[0].OutputTokens, "output tokens must round-trip from metadata")
-	assert.InDelta(t, 0.0123, usage[0].CostUSD, 1e-9, "cost must round-trip from metadata")
+	assert.Equal(t, int64(256), usage[0].CachedInputTokens, "cache-read tokens must round-trip from metadata")
+	assert.Equal(t, int64(768), usage[0].CacheCreationTokens, "cache-write tokens must round-trip from metadata")
+	// The per-bucket breakdown is the only cost state stored, and must survive
+	// the write/read cycle as real columns — usage rows are the only cost
+	// record for accounts with log collection off, so a dropped column here
+	// loses the split permanently.
+	assert.InDelta(t, 0.0071, usage[0].InputCostUSD, 1e-9, "input cost must round-trip from metadata")
+	assert.InDelta(t, 0.0009, usage[0].CachedInputCostUSD, 1e-9, "cache-read cost must round-trip from metadata")
+	assert.InDelta(t, 0.0020, usage[0].CacheCreationCostUSD, 1e-9, "cache-write cost must round-trip from metadata")
+	assert.InDelta(t, 0.0023, usage[0].OutputCostUSD, 1e-9, "output cost must round-trip from metadata")
+	// Aggregates are derived from the stored columns, never stored themselves.
+	assert.InDelta(t, 0.0123, usage[0].TotalCostUSD(), 1e-9, "total is derived from the stored buckets")
+	assert.InDelta(t, 0.0029, usage[0].CacheCostUSD(), 1e-9, "cache cost is derived from the two cache buckets")

 	logs, _, err := s.GetAgentNetworkAccessLogs(ctx, store.LockingStrengthNone, testAccountID, types.AgentNetworkAccessLogFilter{})
 	require.NoError(t, err)
@@ -96,6 +113,14 @@ func TestIngestAccessLog_RealStore_LogCollectionOn(t *testing.T) {
 	require.Equal(t, int64(1), total, "exactly one access-log row expected")
 	require.Len(t, logs, 1, "full access-log row must be written when log collection is on")
 	assert.Equal(t, "gpt-5.4", logs[0].Model, "model must flatten from metadata")
+	assert.Equal(t, int64(256), logs[0].CachedInputTokens, "cache-read tokens must flatten from metadata")
+	assert.Equal(t, int64(768), logs[0].CacheCreationTokens, "cache-write tokens must flatten from metadata")
+	assert.InDelta(t, 0.0029, logs[0].CacheCostUSD(), 1e-9, "cache cost is derived from the two cache buckets")
+	assert.InDelta(t, 0.0123, logs[0].TotalCostUSD(), 1e-9, "total is derived from the stored buckets")
+	assert.InDelta(t, 0.0071, logs[0].InputCostUSD, 1e-9, "input cost must flatten from metadata")
+	assert.InDelta(t, 0.0009, logs[0].CachedInputCostUSD, 1e-9, "cache-read cost must flatten from metadata")
+	assert.InDelta(t, 0.0020, logs[0].CacheCreationCostUSD, 1e-9, "cache-write cost must flatten from metadata")
+	assert.InDelta(t, 0.0023, logs[0].OutputCostUSD, 1e-9, "output cost must flatten from metadata")
 	assert.Equal(t, "hello", logs[0].RequestPrompt, "prompt must be retained when log collection is on")
 	assert.Equal(t, "world", logs[0].ResponseCompletion, "completion must be retained when log collection is on")
 	assert.True(t, logs[0].Stream, "stream flag must flatten from metadata")
@@ -38,7 +38,7 @@ func accessLogRow(id, sessionID string, ts time.Time, opts ...func(*types.AgentN
 		InputTokens:        100,
 		OutputTokens:       50,
 		TotalTokens:        150,
-		CostUSD:            0.01,
+		InputCostUSD:       0.01,
 	}
 	for _, o := range opts {
 		o(e)
@@ -74,7 +74,7 @@ func withTokens(in, out, total int64, cost float64) func(*types.AgentNetworkAcce
 		e.InputTokens = in
 		e.OutputTokens = out
 		e.TotalTokens = total
-		e.CostUSD = cost
+		e.InputCostUSD = cost
 	}
 }

@@ -155,7 +155,7 @@ func TestAccessLogSessions_FoldAndAggregate(t *testing.T) {
 	assert.Equal(t, int64(310), a.InputTokens, "input tokens summed")
 	assert.Equal(t, int64(135), a.OutputTokens, "output tokens summed")
 	assert.Equal(t, int64(445), a.TotalTokens, "total tokens summed")
-	assert.InDelta(t, 0.031, a.CostUSD, 1e-9, "cost summed")
+	assert.InDelta(t, 0.031, a.TotalCostUSD(), 1e-9, "cost summed")
 	assert.Equal(t, "deny", a.Decision, "any deny makes the session a deny")
 	assert.ElementsMatch(t, []string{"openai", "anthropic"}, a.Providers, "distinct providers")
 	assert.ElementsMatch(t, []string{"gpt-5.4", "claude-haiku-4-5"}, a.Models, "distinct models")
@@ -41,8 +41,24 @@ type AgentNetworkAccessLog struct {
 	InputTokens        int64
 	OutputTokens       int64
 	TotalTokens        int64
-	CostUSD            float64
-	Stream             bool
+	// Prompt-cache buckets: read + write token counts.
+	CachedInputTokens   int64
+	CacheCreationTokens int64
+	// Per-bucket cost breakdown — one column per token bucket the provider
+	// bills separately. These four are the only cost state stored: the total
+	// and the cache portion are derived on read (TotalCostUSD / CacheCostUSD)
+	// rather than stored alongside, so a stored aggregate can never drift out
+	// of step with the components it summarises.
+	//
+	// default:0 matters on upgrade: these columns are ALTER TABLE ADD COLUMN
+	// on an existing table, and without it every historical row holds NULL —
+	// which a raw SUM()/scan into float64 can't read. The default backfills
+	// them as 0, so pre-upgrade rows report an unknown split, not an error.
+	InputCostUSD         float64 `gorm:"not null;default:0"`
+	CachedInputCostUSD   float64 `gorm:"not null;default:0"`
+	CacheCreationCostUSD float64 `gorm:"not null;default:0"`
+	OutputCostUSD        float64 `gorm:"not null;default:0"`
+	Stream               bool

 	// Prompt capture. Only populated when prompt collection is enabled
 	// (account master switch AND policy guardrail). Heavy free text.
@@ -60,19 +76,44 @@ type AgentNetworkAccessLog struct {
 // the reverse-proxy AccessLogEntry table.
 func (AgentNetworkAccessLog) TableName() string { return "agent_network_access_log" }

+// CostUSDSQLExpr is the SQL sum of the per-bucket cost columns — the total cost
+// of a row. Used wherever a query has to sort or aggregate on total cost now
+// that no cost_usd column is stored. Plain arithmetic over NOT NULL columns, so
+// it stays portable across SQLite and Postgres.
+const CostUSDSQLExpr = "(input_cost_usd + cached_input_cost_usd + cache_creation_cost_usd + output_cost_usd)"
+
+// TotalCostUSD is the request's total cost: the sum of the four per-bucket
+// costs. Derived rather than stored so it cannot disagree with the breakdown.
+func (a *AgentNetworkAccessLog) TotalCostUSD() float64 {
+	return a.InputCostUSD + a.CachedInputCostUSD + a.CacheCreationCostUSD + a.OutputCostUSD
+}
+
+// CacheCostUSD is the portion of the total billed for prompt-cache buckets:
+// cache reads plus cache writes.
+func (a *AgentNetworkAccessLog) CacheCostUSD() float64 {
+	return a.CachedInputCostUSD + a.CacheCreationCostUSD
+}
+
 // ToAPIResponse renders the flattened entry as the API representation.
 func (a *AgentNetworkAccessLog) ToAPIResponse() api.AgentNetworkAccessLog {
 	out := api.AgentNetworkAccessLog{
-		Id:           a.ID,
-		ServiceId:    a.ServiceID,
-		Timestamp:    a.Timestamp,
-		StatusCode:   a.StatusCode,
-		DurationMs:   int(a.Duration.Milliseconds()),
-		InputTokens:  a.InputTokens,
-		OutputTokens: a.OutputTokens,
-		TotalTokens:  a.TotalTokens,
-		CostUsd:      a.CostUSD,
-		Stream:       &a.Stream,
+		Id:                   a.ID,
+		ServiceId:            a.ServiceID,
+		Timestamp:            a.Timestamp,
+		StatusCode:           a.StatusCode,
+		DurationMs:           int(a.Duration.Milliseconds()),
+		InputTokens:          a.InputTokens,
+		OutputTokens:         a.OutputTokens,
+		TotalTokens:          a.TotalTokens,
+		CachedInputTokens:    a.CachedInputTokens,
+		CacheCreationTokens:  a.CacheCreationTokens,
+		InputCostUsd:         a.InputCostUSD,
+		CachedInputCostUsd:   a.CachedInputCostUSD,
+		CacheCreationCostUsd: a.CacheCreationCostUSD,
+		OutputCostUsd:        a.OutputCostUSD,
+		CostUsd:              a.TotalCostUSD(),
+		CacheCostUsd:         a.CacheCostUSD(),
+		Stream:               &a.Stream,
 	}

 	out.UserId = strPtr(a.UserID)
@@ -112,20 +153,36 @@ func strPtr(s string) *string {
 // summary plus its ordered entries. Assembled in Go from a page of entries — it
 // is not a stored table.
 type AgentNetworkAccessLogSession struct {
-	SessionID    string // empty for a session-less (singleton) request
-	UserID       string
-	GroupIDs     []string // union of the entries' authorising groups
-	StartedAt    time.Time
-	EndedAt      time.Time
-	RequestCount int
-	InputTokens  int64
-	OutputTokens int64
-	TotalTokens  int64
-	CostUSD      float64
-	Providers    []string // distinct vendors seen in the session
-	Models       []string // distinct models seen in the session
-	Decision     string   // "deny" if any entry was denied, else "allow"
-	Entries      []*AgentNetworkAccessLog
+	SessionID            string // empty for a session-less (singleton) request
+	UserID               string
+	GroupIDs             []string // union of the entries' authorising groups
+	StartedAt            time.Time
+	EndedAt              time.Time
+	RequestCount         int
+	InputTokens          int64
+	OutputTokens         int64
+	TotalTokens          int64
+	CachedInputTokens    int64
+	CacheCreationTokens  int64
+	InputCostUSD         float64
+	CachedInputCostUSD   float64
+	CacheCreationCostUSD float64
+	OutputCostUSD        float64
+	Providers            []string // distinct vendors seen in the session
+	Models               []string // distinct models seen in the session
+	Decision             string   // "deny" if any entry was denied, else "allow"
+	Entries              []*AgentNetworkAccessLog
+}
+
+// TotalCostUSD is the session's total cost: the sum of the four per-bucket
+// costs accumulated across its entries.
+func (sess *AgentNetworkAccessLogSession) TotalCostUSD() float64 {
+	return sess.InputCostUSD + sess.CachedInputCostUSD + sess.CacheCreationCostUSD + sess.OutputCostUSD
+}
+
+// CacheCostUSD is the session's prompt-cache spend: cache reads plus writes.
+func (sess *AgentNetworkAccessLogSession) CacheCostUSD() float64 {
+	return sess.CachedInputCostUSD + sess.CacheCreationCostUSD
 }

 // sessionKey is the grouping key for an entry: its session id, or — when the
@@ -205,7 +262,12 @@ func (sess *AgentNetworkAccessLogSession) foldEntry(sk *sessionSeen, e *AgentNet
 	sess.InputTokens += e.InputTokens
 	sess.OutputTokens += e.OutputTokens
 	sess.TotalTokens += e.TotalTokens
-	sess.CostUSD += e.CostUSD
+	sess.CachedInputTokens += e.CachedInputTokens
+	sess.CacheCreationTokens += e.CacheCreationTokens
+	sess.InputCostUSD += e.InputCostUSD
+	sess.CachedInputCostUSD += e.CachedInputCostUSD
+	sess.CacheCreationCostUSD += e.CacheCreationCostUSD
+	sess.OutputCostUSD += e.OutputCostUSD
 	if e.Timestamp.Before(sess.StartedAt) {
 		sess.StartedAt = e.Timestamp
 	}
@@ -248,15 +310,22 @@ func (sess *AgentNetworkAccessLogSession) ToAPIResponse() api.AgentNetworkAccess
 	}

 	out := api.AgentNetworkAccessLogSession{
-		StartedAt:    sess.StartedAt,
-		EndedAt:      sess.EndedAt,
-		RequestCount: sess.RequestCount,
-		InputTokens:  sess.InputTokens,
-		OutputTokens: sess.OutputTokens,
-		TotalTokens:  sess.TotalTokens,
-		CostUsd:      sess.CostUSD,
-		Decision:     sess.Decision,
-		Entries:      entries,
+		StartedAt:            sess.StartedAt,
+		EndedAt:              sess.EndedAt,
+		RequestCount:         sess.RequestCount,
+		InputTokens:          sess.InputTokens,
+		OutputTokens:         sess.OutputTokens,
+		TotalTokens:          sess.TotalTokens,
+		CachedInputTokens:    sess.CachedInputTokens,
+		CacheCreationTokens:  sess.CacheCreationTokens,
+		InputCostUsd:         sess.InputCostUSD,
+		CachedInputCostUsd:   sess.CachedInputCostUSD,
+		CacheCreationCostUsd: sess.CacheCreationCostUSD,
+		OutputCostUsd:        sess.OutputCostUSD,
+		CostUsd:              sess.TotalCostUSD(),
+		CacheCostUsd:         sess.CacheCostUSD(),
+		Decision:             sess.Decision,
+		Entries:              entries,
 	}
 	out.SessionId = strPtr(sess.SessionID)
 	out.UserId = strPtr(sess.UserID)
@@ -54,7 +54,7 @@ var accessLogSortFields = map[string]string{
 	"provider":     "provider",
 	"status_code":  "status_code",
 	"duration":     "duration",
-	"cost_usd":     "cost_usd",
+	"cost_usd":     CostUSDSQLExpr,
 	"total_tokens": "total_tokens",
 	"user_id":      "user_id",
 	"decision":     "decision",
@@ -70,7 +70,7 @@ var accessLogSortFields = map[string]string{
 var sessionSortExprs = map[string]string{ //nolint:gosec // G101 false positive: "total_tokens" sort key, not a credential
 	"timestamp":     "MAX(timestamp)",
 	"started_at":    "MIN(timestamp)",
-	"cost_usd":      "SUM(cost_usd)",
+	"cost_usd":      "SUM" + CostUSDSQLExpr,
 	"total_tokens":  "SUM(total_tokens)",
 	"duration":      "SUM(duration)",
 	"request_count": "COUNT(*)",
@@ -0,0 +1,124 @@
+package types
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// costRow builds an access-log entry carrying only a cost breakdown — the rest
+// of the row is irrelevant to the summation identities under test.
+func costRow(id, session string, ts time.Time, in, cachedIn, cacheCreate, out float64) *AgentNetworkAccessLog {
+	return &AgentNetworkAccessLog{
+		ID:                   id,
+		SessionID:            session,
+		Timestamp:            ts,
+		InputCostUSD:         in,
+		CachedInputCostUSD:   cachedIn,
+		CacheCreationCostUSD: cacheCreate,
+		OutputCostUSD:        out,
+	}
+}
+
+// TestAPIResponse_CostComponentsSumToAggregates is the contract a client adding
+// up an API response depends on: within a single rendered object, the four
+// per-bucket fields sum to cost_usd, and the two cache fields sum to
+// cache_cost_usd. Uses rates that are not exactly representable in binary
+// floating point, so the identity is checked against real arithmetic rather
+// than round numbers.
+func TestAPIResponse_CostComponentsSumToAggregates(t *testing.T) {
+	row := costRow("r1", "s1", time.Now(), 0.000768, 0.0002304, 0.00192, 0.003)
+
+	api := row.ToAPIResponse()
+	assert.InDelta(t, api.InputCostUsd+api.CachedInputCostUsd+api.CacheCreationCostUsd+api.OutputCostUsd,
+		api.CostUsd, 1e-12, "rendered buckets must sum to the rendered cost_usd")
+	assert.InDelta(t, api.CachedInputCostUsd+api.CacheCreationCostUsd, api.CacheCostUsd, 1e-12,
+		"rendered cache buckets must sum to the rendered cache_cost_usd")
+	assert.InDelta(t, 0.0059184, api.CostUsd, 1e-12, "total is the exact sum, not a separately rounded figure")
+	assert.InDelta(t, 0.0021504, api.CacheCostUsd, 1e-12, "cache cost is the exact sum of the two cache buckets")
+}
+
+// TestSessionSummary_SumsMatchSummedEntries proves a session summary equals the
+// sum of the entries it renders: a client that adds up the entries itself must
+// land on the same number the summary reports, per bucket and in total.
+func TestSessionSummary_SumsMatchSummedEntries(t *testing.T) {
+	base := time.Date(2026, 5, 5, 10, 0, 0, 0, time.UTC)
+	entries := []*AgentNetworkAccessLog{
+		costRow("r1", "s1", base, 0.000768, 0.0002304, 0.00192, 0.003),
+		costRow("r2", "s1", base.Add(time.Minute), 0.000625, 0.0009375, 0, 0.005),
+		costRow("r3", "s1", base.Add(2*time.Minute), 0.0000016, 0, 0, 0.0000032),
+	}
+
+	sessions := FoldAccessLogSessions([]string{"s1"}, entries)
+	require.Len(t, sessions, 1)
+	sess := sessions[0].ToAPIResponse()
+
+	var wantInput, wantCachedInput, wantCacheCreation, wantOutput float64
+	for _, e := range entries {
+		wantInput += e.InputCostUSD
+		wantCachedInput += e.CachedInputCostUSD
+		wantCacheCreation += e.CacheCreationCostUSD
+		wantOutput += e.OutputCostUSD
+	}
+
+	assert.InDelta(t, wantInput, sess.InputCostUsd, 1e-12, "session input cost is the sum of its entries")
+	assert.InDelta(t, wantCachedInput, sess.CachedInputCostUsd, 1e-12, "session cache-read cost is the sum of its entries")
+	assert.InDelta(t, wantCacheCreation, sess.CacheCreationCostUsd, 1e-12, "session cache-write cost is the sum of its entries")
+	assert.InDelta(t, wantOutput, sess.OutputCostUsd, 1e-12, "session output cost is the sum of its entries")
+	assert.InDelta(t, wantInput+wantCachedInput+wantCacheCreation+wantOutput, sess.CostUsd, 1e-12,
+		"session total equals the summed entry buckets")
+
+	// Summing the rendered entries must give the same answer as reading the
+	// summary — the property a UI relies on when it totals a table itself.
+	var fromEntries float64
+	for _, e := range sess.Entries {
+		fromEntries += e.CostUsd
+	}
+	assert.InDelta(t, sess.CostUsd, fromEntries, 1e-12, "summary total must match the summed rendered entries")
+
+	// The sub-microdollar row must still contribute; it would vanish under
+	// 6-decimal quantisation.
+	assert.Greater(t, sess.InputCostUsd, 0.001393, "small-cost rows must not be quantised away")
+}
+
+// TestUsageBuckets_SumsMatchSummedRows proves the same identity one level up:
+// a usage bucket equals the sum of the ledger rows folded into it, and the
+// buckets together equal the whole range.
+func TestUsageBuckets_SumsMatchSummedRows(t *testing.T) {
+	day1 := time.Date(2026, 5, 5, 9, 0, 0, 0, time.UTC)
+	day2 := time.Date(2026, 5, 6, 9, 0, 0, 0, time.UTC)
+	rows := []*AgentNetworkUsage{
+		{ID: "u1", Timestamp: day1, InputCostUSD: 0.000768, CachedInputCostUSD: 0.0002304, CacheCreationCostUSD: 0.00192, OutputCostUSD: 0.003},
+		{ID: "u2", Timestamp: day1.Add(time.Hour), InputCostUSD: 0.000625, CachedInputCostUSD: 0.0009375, OutputCostUSD: 0.005},
+		{ID: "u3", Timestamp: day2, InputCostUSD: 0.0000016, OutputCostUSD: 0.0000032},
+	}
+
+	buckets := AggregateUsageByGranularity(rows, UsageGranularityDay)
+	require.Len(t, buckets, 2, "two distinct days expected")
+
+	var total, cache float64
+	for _, b := range buckets {
+		api := b.ToAPIResponse()
+		assert.InDelta(t, api.InputCostUsd+api.CachedInputCostUsd+api.CacheCreationCostUsd+api.OutputCostUsd,
+			api.CostUsd, 1e-12, "each bucket's components must sum to its cost_usd")
+		total += api.CostUsd
+		cache += api.CacheCostUsd
+	}
+
+	var wantTotal, wantCache float64
+	for _, r := range rows {
+		wantTotal += r.TotalCostUSD()
+		wantCache += r.CacheCostUSD()
+	}
+	assert.InDelta(t, wantTotal, total, 1e-12, "buckets must sum to the total across all ledger rows")
+	assert.InDelta(t, wantCache, cache, 1e-12, "buckets must sum to the cache spend across all ledger rows")
+
+	// A month bucket over the same rows must total identically — regrouping
+	// changes the partition, never the sum.
+	monthly := AggregateUsageByGranularity(rows, UsageGranularityMonth)
+	require.Len(t, monthly, 1)
+	assert.InDelta(t, wantTotal, monthly[0].ToAPIResponse().CostUsd, 1e-12,
+		"re-bucketing at a different granularity must preserve the total")
+}
@@ -25,8 +25,19 @@ type AgentNetworkUsage struct {
 	InputTokens        int64
 	OutputTokens       int64
 	TotalTokens        int64
-	CostUSD            float64
-	CreatedAt          time.Time
+	// Prompt-cache buckets: read + write token counts.
+	CachedInputTokens   int64
+	CacheCreationTokens int64
+	// Per-bucket cost breakdown, mirroring AgentNetworkAccessLog — the only
+	// cost state stored; total and cache portion are derived on read. Kept on
+	// the usage ledger too so spend can be attributed per bucket even for
+	// accounts with log collection turned off. See AgentNetworkAccessLog for
+	// why the columns carry a zero default.
+	InputCostUSD         float64 `gorm:"not null;default:0"`
+	CachedInputCostUSD   float64 `gorm:"not null;default:0"`
+	CacheCreationCostUSD float64 `gorm:"not null;default:0"`
+	OutputCostUSD        float64 `gorm:"not null;default:0"`
+	CreatedAt            time.Time
 }

 // TableName keeps usage records in their own stripped table. Named
@@ -34,6 +45,17 @@ type AgentNetworkUsage struct {
 // agent_network_usage table in a shared database.
 func (AgentNetworkUsage) TableName() string { return "agent_network_request_usage" }

+// TotalCostUSD is the request's total cost: the sum of the four per-bucket
+// costs. Derived rather than stored so it cannot disagree with the breakdown.
+func (u *AgentNetworkUsage) TotalCostUSD() float64 {
+	return u.InputCostUSD + u.CachedInputCostUSD + u.CacheCreationCostUSD + u.OutputCostUSD
+}
+
+// CacheCostUSD is the portion of the total billed for prompt-cache buckets.
+func (u *AgentNetworkUsage) CacheCostUSD() float64 {
+	return u.CachedInputCostUSD + u.CacheCreationCostUSD
+}
+
 // AgentNetworkUsageGroup is the normalised many-to-many row linking a usage
 // record to one authorising group, mirroring AgentNetworkAccessLogGroup so the
 // usage overview can filter by group with a `group_id IN (...)` join.
@@ -33,21 +33,45 @@ func ParseUsageGranularity(s string) UsageGranularity {
 // AgentNetworkUsageBucket is one aggregated usage time bucket. PeriodStart is
 // the UTC start of the bucket as YYYY-MM-DD.
 type AgentNetworkUsageBucket struct {
-	PeriodStart  string
-	InputTokens  int64
-	OutputTokens int64
-	TotalTokens  int64
-	CostUSD      float64
+	PeriodStart          string
+	InputTokens          int64
+	OutputTokens         int64
+	TotalTokens          int64
+	CachedInputTokens    int64
+	CacheCreationTokens  int64
+	InputCostUSD         float64
+	CachedInputCostUSD   float64
+	CacheCreationCostUSD float64
+	OutputCostUSD        float64
+}
+
+// TotalCostUSD is the bucket's total spend: the sum of the four per-bucket
+// costs. Derived rather than accumulated separately so it cannot disagree with
+// the components.
+func (b *AgentNetworkUsageBucket) TotalCostUSD() float64 {
+	return b.InputCostUSD + b.CachedInputCostUSD + b.CacheCreationCostUSD + b.OutputCostUSD
+}
+
+// CacheCostUSD is the bucket's prompt-cache spend: cache reads plus writes.
+func (b *AgentNetworkUsageBucket) CacheCostUSD() float64 {
+	return b.CachedInputCostUSD + b.CacheCreationCostUSD
 }

 // ToAPIResponse renders the bucket as the API representation.
 func (b *AgentNetworkUsageBucket) ToAPIResponse() api.AgentNetworkUsageBucket {
 	return api.AgentNetworkUsageBucket{
-		PeriodStart:  b.PeriodStart,
-		InputTokens:  b.InputTokens,
-		OutputTokens: b.OutputTokens,
-		TotalTokens:  b.TotalTokens,
-		CostUsd:      b.CostUSD,
+		PeriodStart:          b.PeriodStart,
+		InputTokens:          b.InputTokens,
+		OutputTokens:         b.OutputTokens,
+		TotalTokens:          b.TotalTokens,
+		CachedInputTokens:    b.CachedInputTokens,
+		CacheCreationTokens:  b.CacheCreationTokens,
+		InputCostUsd:         b.InputCostUSD,
+		CachedInputCostUsd:   b.CachedInputCostUSD,
+		CacheCreationCostUsd: b.CacheCreationCostUSD,
+		OutputCostUsd:        b.OutputCostUSD,
+		CostUsd:              b.TotalCostUSD(),
+		CacheCostUsd:         b.CacheCostUSD(),
 	}
 }

@@ -84,7 +108,12 @@ func AggregateUsageByGranularity(rows []*AgentNetworkUsage, g UsageGranularity)
 		b.InputTokens += r.InputTokens
 		b.OutputTokens += r.OutputTokens
 		b.TotalTokens += r.TotalTokens
-		b.CostUSD += r.CostUSD
+		b.CachedInputTokens += r.CachedInputTokens
+		b.CacheCreationTokens += r.CacheCreationTokens
+		b.InputCostUSD += r.InputCostUSD
+		b.CachedInputCostUSD += r.CachedInputCostUSD
+		b.CacheCreationCostUSD += r.CacheCreationCostUSD
+		b.OutputCostUSD += r.OutputCostUSD
 	}

 	out := make([]*AgentNetworkUsageBucket, 0, len(byPeriod))
@@ -683,3 +683,81 @@ func BackfillPublicIDs[T any](ctx context.Context, db *gorm.DB) error {
 	log.WithContext(ctx).Infof("Backfill of empty public_id in table %s completed", tableName)
 	return nil
 }
+
+// FoldCostAggregatesIntoBuckets migrates a per-request cost table from the old
+// "stored aggregate" shape (cost_usd + cache_cost_usd columns) to the per-bucket
+// breakdown, where the total and cache portion are derived on read instead.
+//
+// The fold preserves both aggregates exactly for historical rows: the cache
+// total moves into cached_input_cost_usd and the remainder into
+// input_cost_usd, so a row's derived total and cache cost still match what it
+// reported before the upgrade. The finer split is genuinely unknown for those
+// rows — the old schema never recorded a read/write or input/output division —
+// so it is lumped rather than guessed; only rows written after the upgrade
+// carry a true four-way split.
+//
+// Dropping the columns before folding would zero every historical row's cost,
+// so the update runs first and the drop only happens once it succeeds. A table
+// with no cost_usd column has already been migrated (or was created fresh) and
+// is skipped.
+func FoldCostAggregatesIntoBuckets[T any](ctx context.Context, db *gorm.DB) error {
+	var model T
+
+	if !db.Migrator().HasTable(&model) {
+		log.WithContext(ctx).Debugf("table for %T does not exist, no cost-bucket migration needed", model)
+		return nil
+	}
+	if !db.Migrator().HasColumn(&model, "cost_usd") {
+		log.WithContext(ctx).Debugf("table for %T has no cost_usd column, cost buckets already migrated", model)
+		return nil
+	}
+
+	stmt := &gorm.Statement{DB: db}
+	if err := stmt.Parse(&model); err != nil {
+		return fmt.Errorf("parse model schema: %w", err)
+	}
+	tableName := stmt.Schema.Table
+
+	// COALESCE guards rows whose new columns were added as NULL by an earlier
+	// AutoMigrate run that predates the NOT NULL default.
+	hasCacheColumn := db.Migrator().HasColumn(&model, "cache_cost_usd")
+	cacheExpr := "0"
+	if hasCacheColumn {
+		cacheExpr = "COALESCE(cache_cost_usd, 0)"
+	}
+
+	if err := db.Transaction(func(tx *gorm.DB) error {
+		// Only touch rows that carry a legacy total and no breakdown yet, so
+		// the migration is idempotent and never overwrites a true split.
+		update := fmt.Sprintf(`UPDATE %s
+			SET input_cost_usd = COALESCE(cost_usd, 0) - %s,
+			    cached_input_cost_usd = %s,
+			    cache_creation_cost_usd = 0,
+			    output_cost_usd = 0
+			WHERE COALESCE(cost_usd, 0) <> 0
+			  AND COALESCE(input_cost_usd, 0) = 0
+			  AND COALESCE(cached_input_cost_usd, 0) = 0
+			  AND COALESCE(cache_creation_cost_usd, 0) = 0
+			  AND COALESCE(output_cost_usd, 0) = 0`, tableName, cacheExpr, cacheExpr)
+		res := tx.Exec(update)
+		if res.Error != nil {
+			return fmt.Errorf("fold legacy cost aggregates in %s: %w", tableName, res.Error)
+		}
+		log.WithContext(ctx).Infof("folded legacy cost aggregates into per-bucket columns for %d rows in table %s", res.RowsAffected, tableName)
+
+		if err := tx.Migrator().DropColumn(&model, "cost_usd"); err != nil {
+			return fmt.Errorf("drop cost_usd from %s: %w", tableName, err)
+		}
+		if hasCacheColumn {
+			if err := tx.Migrator().DropColumn(&model, "cache_cost_usd"); err != nil {
+				return fmt.Errorf("drop cache_cost_usd from %s: %w", tableName, err)
+			}
+		}
+		return nil
+	}); err != nil {
+		return err
+	}
+
+	log.WithContext(ctx).Infof("migration of stored cost aggregates to per-bucket columns in table %s completed", tableName)
+	return nil
+}
@@ -16,6 +16,7 @@ import (
 	"gorm.io/driver/sqlite"
 	"gorm.io/gorm"

+	agentNetworkTypes "github.com/netbirdio/netbird/management/internals/modules/agentnetwork/types"
 	"github.com/netbirdio/netbird/management/server/migration"
 	nbpeer "github.com/netbirdio/netbird/management/server/peer"
 	"github.com/netbirdio/netbird/management/server/testutil"
@@ -639,3 +640,99 @@ func TestCleanupOrphanedResources_SkipsWhenForeignKeyExists(t *testing.T) {
 	db.Model(&testChildWithFK{}).Count(&count)
 	assert.Equal(t, int64(2), count, "Both rows should survive — migration must skip when FK constraint exists")
 }
+
+// legacyCostRow is the pre-breakdown shape of the usage table: cost was stored
+// as a total plus a cache portion, with no per-bucket columns. Used to build a
+// realistic pre-upgrade table for the fold migration to run against.
+type legacyCostRow struct {
+	ID           string `gorm:"primaryKey"`
+	AccountID    string
+	Model        string
+	CostUSD      float64
+	CacheCostUSD float64
+}
+
+func (legacyCostRow) TableName() string { return "agent_network_request_usage" }
+
+// TestFoldCostAggregatesIntoBuckets_PreservesHistoricalCost covers the upgrade
+// path: a table written under the old schema must come out with its per-row
+// total and cache cost unchanged, because dropping cost_usd without folding it
+// forward would silently zero every historical row's spend.
+func TestFoldCostAggregatesIntoBuckets_PreservesHistoricalCost(t *testing.T) {
+	ctx := context.Background()
+	db := setupDatabase(t)
+	// setupDatabase hands back a process-shared database, so start from a clean
+	// table rather than inheriting rows from another test.
+	require.NoError(t, db.Migrator().DropTable(&agentNetworkTypes.AgentNetworkUsage{}))
+
+	require.NoError(t, db.AutoMigrate(&legacyCostRow{}), "legacy table must be created")
+	require.NoError(t, db.Create(&legacyCostRow{
+		ID: "u1", AccountID: "acct-1", Model: "claude-sonnet-4-6", CostUSD: 0.0123, CacheCostUSD: 0.0029,
+	}).Error)
+	require.NoError(t, db.Create(&legacyCostRow{
+		ID: "u2", AccountID: "acct-1", Model: "gpt-4o", CostUSD: 0.5, CacheCostUSD: 0,
+	}).Error)
+	// A zero-cost row (denied / unpriced request) must stay zero, not be touched.
+	require.NoError(t, db.Create(&legacyCostRow{ID: "u3", AccountID: "acct-1", Model: "gw/unpriced"}).Error)
+
+	// AutoMigrate adds the per-bucket columns alongside the legacy ones, exactly
+	// as a real upgrade does before the post-auto migrations run.
+	require.NoError(t, db.AutoMigrate(&agentNetworkTypes.AgentNetworkUsage{}), "new columns must be added")
+
+	require.NoError(t, migration.FoldCostAggregatesIntoBuckets[agentNetworkTypes.AgentNetworkUsage](ctx, db))
+
+	assert.False(t, db.Migrator().HasColumn(&agentNetworkTypes.AgentNetworkUsage{}, "cost_usd"),
+		"legacy cost_usd column must be dropped once folded")
+	assert.False(t, db.Migrator().HasColumn(&agentNetworkTypes.AgentNetworkUsage{}, "cache_cost_usd"),
+		"legacy cache_cost_usd column must be dropped once folded")
+
+	var rows []*agentNetworkTypes.AgentNetworkUsage
+	require.NoError(t, db.Order("id").Find(&rows).Error)
+	require.Len(t, rows, 3)
+
+	// u1: total and cache portion both preserved; the read/write and
+	// input/output splits are unknowable for a legacy row, so the cache total
+	// lands on cached_input and the remainder on input.
+	assert.InDelta(t, 0.0123, rows[0].TotalCostUSD(), 1e-9, "historical total must survive the fold")
+	assert.InDelta(t, 0.0029, rows[0].CacheCostUSD(), 1e-9, "historical cache cost must survive the fold")
+	assert.InDelta(t, 0.0094, rows[0].InputCostUSD, 1e-9, "non-cache remainder lands on input")
+	assert.InDelta(t, 0.0029, rows[0].CachedInputCostUSD, 1e-9, "legacy cache total lands on cached input")
+	assert.Zero(t, rows[0].CacheCreationCostUSD, "legacy rows carry no read/write split to recover")
+	assert.Zero(t, rows[0].OutputCostUSD, "legacy rows carry no input/output split to recover")
+
+	// u2: no cache spend — the whole total is the non-cache remainder.
+	assert.InDelta(t, 0.5, rows[1].TotalCostUSD(), 1e-9, "cache-free historical total must survive")
+	assert.Zero(t, rows[1].CacheCostUSD(), "a cache-free row must stay cache-free")
+
+	// u3: zero stays zero rather than being rewritten.
+	assert.Zero(t, rows[2].TotalCostUSD(), "an unpriced row must remain unpriced")
+}
+
+// TestFoldCostAggregatesIntoBuckets_SkipsAlreadyMigrated proves the migration is
+// safe to re-run: with no legacy column present it is a no-op that leaves a
+// true four-way split untouched.
+func TestFoldCostAggregatesIntoBuckets_SkipsAlreadyMigrated(t *testing.T) {
+	ctx := context.Background()
+	db := setupDatabase(t)
+	require.NoError(t, db.Migrator().DropTable(&agentNetworkTypes.AgentNetworkUsage{}))
+
+	require.NoError(t, db.AutoMigrate(&agentNetworkTypes.AgentNetworkUsage{}))
+	// Timestamp must be set explicitly: a zero time.Time serialises as
+	// '0000-00-00 00:00:00', which MySQL rejects under strict mode.
+	require.NoError(t, db.Create(&agentNetworkTypes.AgentNetworkUsage{
+		ID: "u1", AccountID: "acct-1", Model: "claude-sonnet-4-6",
+		Timestamp:    time.Date(2026, 5, 5, 9, 0, 0, 0, time.UTC),
+		InputCostUSD: 0.001, CachedInputCostUSD: 0.002, CacheCreationCostUSD: 0.003, OutputCostUSD: 0.004,
+	}).Error)
+
+	require.NoError(t, migration.FoldCostAggregatesIntoBuckets[agentNetworkTypes.AgentNetworkUsage](ctx, db),
+		"running against an already-migrated table must be a no-op, not an error")
+
+	var row agentNetworkTypes.AgentNetworkUsage
+	require.NoError(t, db.First(&row, "id = ?", "u1").Error)
+	assert.InDelta(t, 0.001, row.InputCostUSD, 1e-9, "a true split must not be rewritten")
+	assert.InDelta(t, 0.002, row.CachedInputCostUSD, 1e-9)
+	assert.InDelta(t, 0.003, row.CacheCreationCostUSD, 1e-9)
+	assert.InDelta(t, 0.004, row.OutputCostUSD, 1e-9)
+	assert.InDelta(t, 0.01, row.TotalCostUSD(), 1e-9, "derived total sums the four buckets")
+}
@@ -71,7 +71,7 @@ func (s *SqlStore) GetAgentNetworkMetrics(ctx context.Context) (AgentNetworkMetr
 	usageRow := db.Model(&agentNetworkTypes.AgentNetworkUsage{}).
 		Select("COALESCE(SUM(input_tokens), 0) AS input_tokens, " +
 			"COALESCE(SUM(output_tokens), 0) AS output_tokens, " +
-			"COALESCE(SUM(cost_usd), 0) AS cost_usd").Row()
+			"COALESCE(SUM" + agentNetworkTypes.CostUSDSQLExpr + ", 0) AS cost_usd").Row()
 	if err := usageRow.Scan(&m.InputTokens, &m.OutputTokens, &m.CostUSD); err != nil {
 		return AgentNetworkMetrics{}, fmt.Errorf("scan agent network usage metrics: %w", err)
 	}
@@ -37,7 +37,7 @@ func TestAgentNetworkUsage_RealStore_RoundTrip(t *testing.T) {
 		InputTokens:        1200,
 		OutputTokens:       640,
 		TotalTokens:        1840,
-		CostUSD:            0.0231,
+		InputCostUSD:       0.0231,
 	}
 	usageGroups := []agentNetworkTypes.AgentNetworkUsageGroup{
 		{UsageID: usage.ID, GroupID: "grp-eng", AccountID: accountID},
@@ -71,7 +71,7 @@ func TestAgentNetworkUsage_RealStore_RoundTrip(t *testing.T) {
 		InputTokens:  1200,
 		OutputTokens: 640,
 		TotalTokens:  1840,
-		CostUSD:      0.0231,
+		InputCostUSD: 0.0231,
 	}
 	entryGroups := []agentNetworkTypes.AgentNetworkAccessLogGroup{
 		{LogID: entry.ID, GroupID: "grp-eng", AccountID: accountID},
@@ -127,7 +127,7 @@ func TestAgentNetworkUsageOverview_DailyAggregation(t *testing.T) {
 	mk := func(id string, ts time.Time, model string, in, out int64, cost float64) *agentNetworkTypes.AgentNetworkUsage {
 		return &agentNetworkTypes.AgentNetworkUsage{
 			ID: id, AccountID: accountID, Timestamp: ts, Model: model,
-			InputTokens: in, OutputTokens: out, TotalTokens: in + out, CostUSD: cost,
+			InputTokens: in, OutputTokens: out, TotalTokens: in + out, InputCostUSD: cost,
 		}
 	}
 	require.NoError(t, s.CreateAgentNetworkUsage(ctx, mk("u1", day1, "gpt-4o", 100, 50, 0.10), nil))
@@ -143,7 +143,7 @@ func TestAgentNetworkUsageOverview_DailyAggregation(t *testing.T) {
 	assert.Equal(t, "2026-05-05", buckets[0].PeriodStart, "oldest-first ordering")
 	assert.Equal(t, int64(300), buckets[0].InputTokens, "same-day input tokens summed")
 	assert.Equal(t, int64(130), buckets[0].OutputTokens)
-	assert.InDelta(t, 0.30, buckets[0].CostUSD, 1e-9, "same-day cost summed")
+	assert.InDelta(t, 0.30, buckets[0].TotalCostUSD(), 1e-9, "same-day cost summed")
 	assert.Equal(t, "2026-05-06", buckets[1].PeriodStart)
 	assert.Equal(t, int64(15), buckets[1].TotalTokens)

@@ -174,7 +174,7 @@ func TestAgentNetworkAccessLogSessions_RealStore(t *testing.T) {
 			ID: id, AccountID: accountID, ServiceID: "svc", Timestamp: ts,
 			UserID: user, StatusCode: 200, Provider: provider, Model: model,
 			SessionID: session, Decision: decision,
-			InputTokens: 100, OutputTokens: 50, TotalTokens: 150, CostUSD: cost,
+			InputTokens: 100, OutputTokens: 50, TotalTokens: 150, InputCostUSD: cost,
 		}
 	}

@@ -207,7 +207,7 @@ func TestAgentNetworkAccessLogSessions_RealStore(t *testing.T) {
 	s1 := sessions[2]
 	assert.Equal(t, 2, s1.RequestCount, "s1 has two requests")
 	assert.Equal(t, int64(300), s1.TotalTokens, "tokens summed across the session")
-	assert.InDelta(t, 0.30, s1.CostUSD, 1e-9, "cost summed across the session")
+	assert.InDelta(t, 0.30, s1.TotalCostUSD(), 1e-9, "cost summed across the session")
 	assert.Equal(t, "alice", s1.UserID)
 	assert.Equal(t, "allow", s1.Decision)
 	// SQLite hands times back in time.Local; normalise to UTC so the instant is
@@ -650,6 +650,14 @@ func getMigrationsPostAuto(ctx context.Context) []migrationFunc {
 		func(db *gorm.DB) error {
 			return migration.DropIndex[proxy.Proxy](ctx, db, "idx_proxy_account_id_unique")
 		},
+		// Post-auto so the per-bucket cost columns already exist when the legacy
+		// aggregates are folded into them and dropped.
+		func(db *gorm.DB) error {
+			return migration.FoldCostAggregatesIntoBuckets[agentNetworkTypes.AgentNetworkAccessLog](ctx, db)
+		},
+		func(db *gorm.DB) error {
+			return migration.FoldCostAggregatesIntoBuckets[agentNetworkTypes.AgentNetworkUsage](ctx, db)
+		},
 	}
 }