Sub2API v1.0 - AI API 网关（二开初始版本，基于上游 Wei-Shaw/sub2api）

backend/internal/service/openai_compat_prompt_cache_key_test.go

@@ -0,0 +1,138 @@
+package service
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+
+	"github.com/Wei-Shaw/sub2api/internal/pkg/apicompat"
+	"github.com/stretchr/testify/require"
+)
+
+func mustRawJSON(t *testing.T, s string) json.RawMessage {
+	t.Helper()
+	return json.RawMessage(s)
+}
+
+func TestShouldAutoInjectPromptCacheKeyForCompat(t *testing.T) {
+	require.True(t, shouldAutoInjectPromptCacheKeyForCompat("gpt-5.5"))
+	require.True(t, shouldAutoInjectPromptCacheKeyForCompat("gpt-5.5-pro"))
+	require.True(t, shouldAutoInjectPromptCacheKeyForCompat("gpt-5.4"))
+	require.True(t, shouldAutoInjectPromptCacheKeyForCompat("gpt-5.4-mini"))
+	require.True(t, shouldAutoInjectPromptCacheKeyForCompat("gpt-5.2"))
+	require.True(t, shouldAutoInjectPromptCacheKeyForCompat("gpt-5.3"))
+	require.True(t, shouldAutoInjectPromptCacheKeyForCompat("gpt-5.3-codex"))
+	require.True(t, shouldAutoInjectPromptCacheKeyForCompat("gpt-5.3-codex-spark"))
+	require.False(t, shouldAutoInjectPromptCacheKeyForCompat("gpt-4o"))
+}
+
+func TestDeriveCompatPromptCacheKey_StableAcrossLaterTurns(t *testing.T) {
+	base := &apicompat.ChatCompletionsRequest{
+		Model: "gpt-5.4",
+		Messages: []apicompat.ChatMessage{
+			{Role: "system", Content: mustRawJSON(t, `"You are helpful."`)},
+			{Role: "user", Content: mustRawJSON(t, `"Hello"`)},
+		},
+	}
+	extended := &apicompat.ChatCompletionsRequest{
+		Model: "gpt-5.4",
+		Messages: []apicompat.ChatMessage{
+			{Role: "system", Content: mustRawJSON(t, `"You are helpful."`)},
+			{Role: "user", Content: mustRawJSON(t, `"Hello"`)},
+			{Role: "assistant", Content: mustRawJSON(t, `"Hi there!"`)},
+			{Role: "user", Content: mustRawJSON(t, `"How are you?"`)},
+		},
+	}
+
+	k1 := deriveCompatPromptCacheKey(base, "gpt-5.4")
+	k2 := deriveCompatPromptCacheKey(extended, "gpt-5.4")
+	require.Equal(t, k1, k2, "cache key should be stable across later turns")
+	require.NotEmpty(t, k1)
+}
+
+func TestDeriveCompatPromptCacheKey_DiffersAcrossSessions(t *testing.T) {
+	req1 := &apicompat.ChatCompletionsRequest{
+		Model: "gpt-5.4",
+		Messages: []apicompat.ChatMessage{
+			{Role: "user", Content: mustRawJSON(t, `"Question A"`)},
+		},
+	}
+	req2 := &apicompat.ChatCompletionsRequest{
+		Model: "gpt-5.4",
+		Messages: []apicompat.ChatMessage{
+			{Role: "user", Content: mustRawJSON(t, `"Question B"`)},
+		},
+	}
+
+	k1 := deriveCompatPromptCacheKey(req1, "gpt-5.4")
+	k2 := deriveCompatPromptCacheKey(req2, "gpt-5.4")
+	require.NotEqual(t, k1, k2, "different first user messages should yield different keys")
+}
+
+func TestDeriveCompatPromptCacheKey_UsesResolvedSparkFamily(t *testing.T) {
+	req := &apicompat.ChatCompletionsRequest{
+		Model: "gpt-5.3-codex-spark",
+		Messages: []apicompat.ChatMessage{
+			{Role: "user", Content: mustRawJSON(t, `"Question A"`)},
+		},
+	}
+
+	k1 := deriveCompatPromptCacheKey(req, "gpt-5.3-codex-spark")
+	k2 := deriveCompatPromptCacheKey(req, " openai/gpt-5.3-codex-spark ")
+	require.NotEmpty(t, k1)
+	require.Equal(t, k1, k2, "resolved spark family should derive a stable compat cache key")
+}
+
+func TestDeriveAnthropicCompatPromptCacheKey_StableAcrossLaterTurns(t *testing.T) {
+	base := &apicompat.AnthropicRequest{
+		Model:  "claude-sonnet-4-5",
+		System: mustRawJSON(t, `"You are helpful."`),
+		Messages: []apicompat.AnthropicMessage{
+			{Role: "user", Content: mustRawJSON(t, `"Open repo"`)},
+		},
+	}
+	extended := &apicompat.AnthropicRequest{
+		Model:  "claude-sonnet-4-5",
+		System: mustRawJSON(t, `"You are helpful."`),
+		Messages: []apicompat.AnthropicMessage{
+			{Role: "user", Content: mustRawJSON(t, `"Open repo"`)},
+			{Role: "assistant", Content: mustRawJSON(t, `"Opened."`)},
+			{Role: "user", Content: mustRawJSON(t, `"Run tests"`)},
+		},
+	}
+
+	k1 := deriveAnthropicCompatPromptCacheKey(base, "gpt-5.3-codex")
+	k2 := deriveAnthropicCompatPromptCacheKey(extended, "gpt-5.3-codex")
+	require.NotEmpty(t, k1)
+	require.Equal(t, k1, k2, "cache key should stay stable as later Claude Code turns append history")
+}
+
+func TestDeriveAnthropicCompatPromptCacheKey_UsesCacheControlAnchors(t *testing.T) {
+	base := &apicompat.AnthropicRequest{
+		Model: "claude-sonnet-4-5",
+		System: mustRawJSON(t, `[
+			{"type":"text","text":"project instructions","cache_control":{"type":"ephemeral"}}
+		]`),
+		Messages: []apicompat.AnthropicMessage{
+			{Role: "user", Content: mustRawJSON(t, `[
+				{"type":"text","text":"repo anchor","cache_control":{"type":"ephemeral"}}
+			]`)},
+		},
+	}
+	extended := &apicompat.AnthropicRequest{
+		Model:  base.Model,
+		System: base.System,
+		Messages: []apicompat.AnthropicMessage{
+			base.Messages[0],
+			{Role: "assistant", Content: mustRawJSON(t, `[{"type":"text","text":"Opened."}]`)},
+			{Role: "user", Content: mustRawJSON(t, `[{"type":"text","text":"Run tests"}]`)},
+		},
+	}
+
+	k1 := deriveAnthropicCompatPromptCacheKey(base, "gpt-5.4")
+	k2 := deriveAnthropicCompatPromptCacheKey(extended, "gpt-5.4")
+	require.NotEmpty(t, k1)
+	require.Equal(t, k1, k2)
+	require.True(t, strings.HasPrefix(k1, "anthropic-cache-"))
+	require.False(t, strings.HasPrefix(k1, compatPromptCacheKeyPrefix))
+}