feat(quality): A4 — L2 Pro premium judge (8 dims, gpt-4o, Pro-gated, opt-in)

routes/translate_routes.py

@@ -1455,6 +1455,49 @@ async def _run_translation_job(
             except Exception:
                 pass
 
+        # ------------------------------------------------------------------
+        # Quality L2 layer (Track A4 — Pro premium judge)
+        # Stronger LLM (gpt-4o default), 8 dimensions, 15 samples.
+        # Gated to Pro+ plans (configurable via QUALITY_L2_TIER_GATE).
+        # Default OFF everywhere — observation first.
+        # Cost: ~$0.005–$0.02/job (gpt-4o), ~$0.001/job (gpt-4o-mini).
+        # ------------------------------------------------------------------
+        if getattr(config, "QUALITY_L2_ENABLED", False) and quality_samples:
+            try:
+                from services.quality import run_l2_check
+
+                # Tier gate: Pro+ plans only (unless gate is disabled)
+                user_tier = (
+                    _tier_for_quota(current_user.plan) if current_user else "free"
+                )
+                tier_gate_on = getattr(config, "QUALITY_L2_TIER_GATE", True)
+                if not tier_gate_on or user_tier in ("pro", "business", "enterprise"):
+                    translated_chunks_for_l2 = [s["translated"] for s in quality_samples]
+                    l2_result = await run_l2_check(
+                        source_chunks=[""] * len(translated_chunks_for_l2),
+                        translated_chunks=translated_chunks_for_l2,
+                        target_lang=target_lang,
+                        l0_failed_indices=l0_failed_indices,
+                        job_id=job_id,
+                        file_extension=file_extension,
+                        max_samples=getattr(config, "QUALITY_L2_SAMPLE_SIZE", 15),
+                        min_chunks=getattr(config, "QUALITY_L2_MIN_CHUNKS", 20),
+                        log_only=getattr(config, "QUALITY_L2_LOG_ONLY", True),
+                    )
+                else:
+                    # Free/Starter user — skip L2 silently (gated)
+                    logger.info(
+                        "quality_l2_check_skipped",
+                        job_id=job_id,
+                        reason="tier_gated",
+                        tier=user_tier,
+                    )
+            except Exception as l2_err:
+                # L2 must NEVER break a job. Log and continue.
+                logger.warning(
+                    f"Job {job_id}: quality L2 layer failed: {l2_err}"
+                )
+
         if user_id:
             # Determine cost factor based on selected provider and model
             cost_factor = 1