test(contracts): VCR replay provider contract tests

docs/WORKLOG.md

@@ -1,3 +1,9 @@
+2025-12-26 20:31 UTC - Provider contract VCR replay tests
+- Files: tests/contracts/provider.contract.test.ts; tests/contracts/vcr/loadCassette.ts; tests/contracts/vcr/types.ts; tests/contracts/cassettes/*.json; docs/WORKLOG.md
+- Why: Provider contract tests were a skipped scaffold; we need deterministic replay tests to validate real adapter behavior without network calls and without placeholder assertions.
+- Details: Adds replay-only VCR cassettes that drive real `OpenAIAdapter.translate()` and `GeminiAdapter.translate()` while mocking only provider SDK boundaries; asserts JSON parsing, token accounting, cost wiring, and OpenAI metrics recording.
+- Tests: `npm test`
+
 2025-12-24 11:23 UTC - Migration recovery UI gate
 - Files: App.tsx; components/MigrationRecovery.tsx; tests/components/MigrationRecovery.test.tsx; docs/WORKLOG.md
 - Why: When the DB is newer/corrupted/blocked or a migration failed, users need a clear recovery path (restore from backup, upload backup, or start fresh) instead of a silent failure.

tests/contracts/cassettes/gemini-happy-path.json

@@ -0,0 +1,24 @@
+{
+  "name": "gemini-happy-path",
+  "provider": "Gemini",
+  "model": "gemini-2.5-flash",
+  "request": {
+    "title": "Test Title",
+    "content": "今天天气很好。",
+    "systemPrompt": "Translate this Chinese text to English.",
+    "temperature": 0.3,
+    "maxOutputTokens": 512
+  },
+  "mock": {
+    "responseText": "{\"translatedTitle\":\"Test Title\",\"translation\":\"The weather is very good today.\",\"footnotes\":[],\"suggestedIllustrations\":[],\"proposal\":null}",
+    "usageMetadata": { "promptTokenCount": 14, "candidatesTokenCount": 9 }
+  },
+  "expected": {
+    "translatedTitle": "Test Title",
+    "translation": "The weather is very good today.",
+    "promptTokens": 14,
+    "completionTokens": 9,
+    "estimatedCost": 0.000008
+  }
+}
+

tests/contracts/cassettes/openai-happy-path.json

@@ -0,0 +1,33 @@
+{
+  "name": "openai-happy-path",
+  "provider": "OpenAI",
+  "model": "gpt-4o-mini",
+  "request": {
+    "title": "Test Title",
+    "content": "今天天气很好。",
+    "systemPrompt": "Translate this Chinese text to English.",
+    "temperature": 0.3,
+    "maxOutputTokens": 512
+  },
+  "mock": {
+    "sdkResponse": {
+      "choices": [
+        {
+          "finish_reason": "stop",
+          "message": {
+            "content": "{\"translatedTitle\":\"Test Title\",\"translation\":\"The weather is very nice today.\",\"footnotes\":[],\"suggestedIllustrations\":[]}"
+          }
+        }
+      ],
+      "usage": { "prompt_tokens": 15, "completion_tokens": 8 }
+    }
+  },
+  "expected": {
+    "translatedTitle": "Test Title",
+    "translation": "The weather is very nice today.",
+    "promptTokens": 15,
+    "completionTokens": 8,
+    "estimatedCost": 0.00003
+  }
+}
+

tests/contracts/cassettes/openai-medium-chapter.json

@@ -0,0 +1,33 @@
+{
+  "name": "openai-medium-chapter",
+  "provider": "OpenAI",
+  "model": "gpt-4o-mini",
+  "request": {
+    "title": "Chapter 1",
+    "content": "그날 하늘은 맑았다. 그날 하늘은 맑았다. 그날 하늘은 맑았다. 그날 하늘은 맑았다. 그날 하늘은 맑았다. 그날 하늘은 맑았다. 그날 하늘은 맑았다. 그날 하늘은 맑았다. 그날 하늘은 맑았다. 그날 하늘은 맑았다.",
+    "systemPrompt": "Translate this Korean web novel chapter to English.",
+    "temperature": 0.7,
+    "maxOutputTokens": 2048
+  },
+  "mock": {
+    "sdkResponse": {
+      "choices": [
+        {
+          "finish_reason": "stop",
+          "message": {
+            "content": "{\"translatedTitle\":\"Chapter 1\",\"translation\":\"That day, the sky was clear. That day, the sky was clear. That day, the sky was clear. That day, the sky was clear. That day, the sky was clear. That day, the sky was clear. That day, the sky was clear. That day, the sky was clear. That day, the sky was clear. That day, the sky was clear.\",\"footnotes\":[],\"suggestedIllustrations\":[]}"
+          }
+        }
+      ],
+      "usage": { "prompt_tokens": 1000, "completion_tokens": 850 }
+    }
+  },
+  "expected": {
+    "translatedTitle": "Chapter 1",
+    "translation": "That day, the sky was clear. That day, the sky was clear. That day, the sky was clear. That day, the sky was clear. That day, the sky was clear. That day, the sky was clear. That day, the sky was clear. That day, the sky was clear. That day, the sky was clear. That day, the sky was clear.",
+    "promptTokens": 1000,
+    "completionTokens": 850,
+    "estimatedCost": 0.00092
+  }
+}
+