feat(pricing-sync): make the age cutoff and keep list configurable

Add the -max-age-months and -keep flags, with PRICING_MAX_AGE_MONTHS and
PRICING_KEEP make variables. A built-in list keeps ids that are still served.

Makefile

@@ -40,8 +40,12 @@ yaegi-check:
 # pruning rule and naming-bridge mechanism. Not run by CI (network
 # fetch, and the generated table is committed); an operator re-runs this
 # by hand when LiteLLM's own pricing drifts.
+# PRICING_MAX_AGE_MONTHS drops entries older than N months (0 = keep all);
+# PRICING_KEEP is a comma-separated list of bare ids exempt from that rule.
+PRICING_MAX_AGE_MONTHS ?= 12
+PRICING_KEEP ?=
 pricing-sync:
-	cd tools/pricing-sync && GOWORK=off go run . $(CURDIR)
+	cd tools/pricing-sync && GOWORK=off go run . -max-age-months=$(PRICING_MAX_AGE_MONTHS) -keep=$(PRICING_KEEP) $(CURDIR)
 	gofmt -w pricing_data_gen.go
 
 INTEGRATION_COMPOSE := integration/docker-compose.yml

tools/pricing-sync/main.go

@@ -60,9 +60,11 @@
 //  4. Freshness: an entry is dropped when LiteLLM's own deprecation_date
 //     has already passed, or when a full calendar date embedded in its
 //     bare id ("claude-opus-4-1-20250805", "gpt-4o-2024-11-20") is
-//     older than maxModelAgeMonths. LiteLLM carries no release date, so
-//     an id with no such date and no deprecation_date is always kept:
-//     an undated alias is never dropped on a guess.
+//     older than the -max-age-months flag (default 12; 0 turns the whole
+//     rule off). LiteLLM carries no release date, so an id with no such
+//     date and no deprecation_date is always kept: an undated alias is
+//     never dropped on a guess. An id in alwaysKeep, or in the -keep
+//     flag's comma-separated list, is exempt.
 //
 // # Bare-id collision resolution
 //
@@ -101,6 +103,7 @@ import (
 	"crypto/sha256"
 	"encoding/hex"
 	"encoding/json"
+	"flag"
 	"fmt"
 	"go/format"
 	"io"
@@ -136,20 +139,37 @@ const microUSDPerUSDPerToken = 1e12
 // this specific, known case.
 const sampleSpecKey = "sample_spec"
 
-// maxModelAgeMonths is the freshness rule's age cutoff for a date embedded
-// in a bare model id.
-const maxModelAgeMonths = 12
+// defaultMaxAgeMonths is the -max-age-months flag's default.
+const defaultMaxAgeMonths = 12
+
+// alwaysKeep lists bare ids the freshness rule never drops, because they
+// are still served after their age or deprecation date says otherwise.
+var alwaysKeep = map[string]bool{
+	"claude-sonnet-4-5-20250929": true,
+}
+
+// pruneOptions is the freshness rule's configuration. maxAgeMonths <= 0
+// turns the rule off.
+type pruneOptions struct {
+	now          time.Time
+	keep         map[string]bool
+	maxAgeMonths int
+}
 
 // idDatePattern finds a full calendar date in a model id, as YYYYMMDD or
 // YYYY-MM-DD, delimited by the id's ends or a "-" or "_".
 var idDatePattern = regexp.MustCompile(`(?:^|[-_])(20\d{2})-?(0[1-9]|1[0-2])-?(0[1-9]|[12]\d|3[01])(?:$|[-_])`)
 
 // isStale reports whether an entry fails the freshness rule: its
-// deprecation_date (YYYY-MM-DD) is before now, or a date embedded in
-// bareID is more than maxModelAgeMonths before now.
-func isStale(bareID, deprecationDate string, now time.Time) bool {
+// deprecation_date (YYYY-MM-DD) is before opts.now, or a date embedded in
+// bareID is more than opts.maxAgeMonths before it. Ids in opts.keep and
+// alwaysKeep never fail.
+func isStale(bareID, deprecationDate string, opts pruneOptions) bool {
+	if opts.maxAgeMonths <= 0 || opts.keep[bareID] || alwaysKeep[bareID] {
+		return false
+	}
 	if deprecationDate != "" {
-		if d, err := time.Parse("2006-01-02", deprecationDate); err == nil && d.Before(now) {
+		if d, err := time.Parse("2006-01-02", deprecationDate); err == nil && d.Before(opts.now) {
 			return true
 		}
 	}
@@ -161,7 +181,7 @@ func isStale(bareID, deprecationDate string, now time.Time) bool {
 	if err != nil {
 		return false
 	}
-	return d.Before(now.AddDate(0, -maxModelAgeMonths, 0))
+	return d.Before(opts.now.AddDate(0, -opts.maxAgeMonths, 0))
 }
 
 // allowedProviders is the pruning rule's provider allowlist — see the
@@ -290,9 +310,18 @@ func main() {
 }
 
 func run() error {
+	maxAge := flag.Int("max-age-months", defaultMaxAgeMonths, "drop entries older than this many months; 0 disables the freshness rule")
+	keepList := flag.String("keep", "", "comma-separated bare ids the freshness rule never drops")
+	flag.Parse()
 	repoRoot := "."
-	if len(os.Args) > 1 {
-		repoRoot = os.Args[1]
+	if flag.NArg() > 0 {
+		repoRoot = flag.Arg(0)
+	}
+	keep := map[string]bool{}
+	for _, id := range strings.Split(*keepList, ",") {
+		if id = strings.TrimSpace(id); id != "" {
+			keep[id] = true
+		}
 	}
 	outPath := filepath.Join(repoRoot, "pricing_data_gen.go")
 
@@ -304,7 +333,7 @@ func run() error {
 		return fmt.Errorf("fetch %s: %w", litellmSourceURL, err)
 	}
 
-	table, totalUpstream, err := parseAndPrune(data, time.Now())
+	table, totalUpstream, err := parseAndPrune(data, pruneOptions{now: time.Now(), maxAgeMonths: *maxAge, keep: keep})
 	if err != nil {
 		return fmt.Errorf("parse and prune: %w", err)
 	}
@@ -355,7 +384,7 @@ func fetchLiteLLMPrices(ctx context.Context, url string) ([]byte, error) {
 // chooseWinner's deterministic bare-id collision resolution. It returns
 // the pruned table and the total number of top-level keys data carried
 // (including ones this function skips), for the summary line run prints.
-func parseAndPrune(data []byte, now time.Time) (map[string]builtinEntry, int, error) {
+func parseAndPrune(data []byte, opts pruneOptions) (map[string]builtinEntry, int, error) {
 	var raw map[string]json.RawMessage
 	if err := json.Unmarshal(data, &raw); err != nil {
 		return nil, 0, fmt.Errorf("decode top-level object: %w", err)
@@ -382,7 +411,7 @@ func parseAndPrune(data []byte, now time.Time) (map[string]builtinEntry, int, er
 		}
 
 		bare, isBareKey := bareModelID(key, e.LiteLLMProvider)
-		if isStale(bare, e.DeprecationDate, now) {
+		if isStale(bare, e.DeprecationDate, opts) {
 			continue
 		}
 		byBare[bare] = append(byBare[bare], candidate{

tools/pricing-sync/main_test.go

@@ -9,7 +9,10 @@ import (
 	"time"
 )
 
-var fixtureNow = time.Date(2026, time.August, 1, 0, 0, 0, 0, time.UTC)
+var (
+	fixtureNow  = time.Date(2026, time.August, 1, 0, 0, 0, 0, time.UTC)
+	fixtureOpts = pruneOptions{now: fixtureNow, maxAgeMonths: defaultMaxAgeMonths}
+)
 
 // fixtureJSON is a small, hand-built stand-in for LiteLLM's real
 // model_prices_and_context_window.json, covering every branch of the
@@ -119,7 +122,7 @@ const fixtureUpstreamKeyCount = 17
 // out, covering every pruning-rule branch fixtureJSON's own doc comment
 // lists.
 func TestParseAndPrune_Golden(t *testing.T) {
-	got, totalUpstream, err := parseAndPrune([]byte(fixtureJSON), fixtureNow)
+	got, totalUpstream, err := parseAndPrune([]byte(fixtureJSON), fixtureOpts)
 	if err != nil {
 		t.Fatalf("parseAndPrune: %v", err)
 	}
@@ -289,7 +292,8 @@ func TestIsStale(t *testing.T) {
 	}
 	for _, tc := range tests {
 		t.Run(tc.name, func(t *testing.T) {
-			if got := isStale(tc.id, tc.deprecated, now); got != tc.want {
+			opts := pruneOptions{now: now, maxAgeMonths: defaultMaxAgeMonths}
+			if got := isStale(tc.id, tc.deprecated, opts); got != tc.want {
 				t.Errorf("isStale(%q, %q) = %v, want %v", tc.id, tc.deprecated, got, tc.want)
 			}
 		})
@@ -302,7 +306,7 @@ func TestParseAndPrune_DropsStaleEntries(t *testing.T) {
   "gpt-old-2024-05-13": {"litellm_provider": "openai", "mode": "chat", "input_cost_per_token": 1e-6, "output_cost_per_token": 2e-6},
   "gpt-dead": {"litellm_provider": "openai", "mode": "chat", "deprecation_date": "2026-01-01", "input_cost_per_token": 1e-6, "output_cost_per_token": 2e-6}
 }`
-	got, _, err := parseAndPrune([]byte(data), fixtureNow)
+	got, _, err := parseAndPrune([]byte(data), fixtureOpts)
 	if err != nil {
 		t.Fatalf("parseAndPrune: %v", err)
 	}
@@ -313,3 +317,29 @@ func TestParseAndPrune_DropsStaleEntries(t *testing.T) {
 		t.Errorf("gpt-fresh missing from %v", got)
 	}
 }
+
+func TestIsStale_Options(t *testing.T) {
+	now := time.Date(2026, time.September, 29, 0, 0, 0, 0, time.UTC)
+	const old = "gpt-4o-2024-08-06"
+	tests := []struct {
+		name string
+		opts pruneOptions
+		id   string
+		want bool
+	}{
+		{"default drops old", pruneOptions{now: now, maxAgeMonths: 12}, old, true},
+		{"zero disables rule", pruneOptions{now: now, maxAgeMonths: 0}, old, false},
+		{"negative disables rule", pruneOptions{now: now, maxAgeMonths: -1}, old, false},
+		{"longer window keeps", pruneOptions{now: now, maxAgeMonths: 36}, old, false},
+		{"shorter window drops more", pruneOptions{now: now, maxAgeMonths: 3}, "model-2026-03-01", true},
+		{"keep flag exempts", pruneOptions{now: now, maxAgeMonths: 12, keep: map[string]bool{old: true}}, old, false},
+		{"alwaysKeep exempts", pruneOptions{now: now, maxAgeMonths: 12}, "claude-sonnet-4-5-20250929", false},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			if got := isStale(tc.id, "", tc.opts); got != tc.want {
+				t.Errorf("isStale(%q) = %v, want %v", tc.id, got, tc.want)
+			}
+		})
+	}
+}