chore: mark US-002 as passing, update progress log

Author: LoCoBench Bot

ralph-gapfill-docgen/prd.json

@@ -29,8 +29,8 @@
         "Task registered"
       ],
       "priority": 2,
-      "passes": false,
-      "notes": "Istio Pilot: pilot/pkg/xds/ads.go (ADS server), pilot/pkg/model/push_context.go, pilot/pkg/networking/core/. Search for DiscoveryServer struct."
+      "passes": true,
+      "notes": "Istio Pilot at f8af3caeb1 (master 2026-02-16). 13 required_topics covering DiscoveryServer, ADS, PushContext, ServiceRegistry. 5 file_references (discovery.go, ads.go, push_context.go, serviceregistry/kube/controller, networking/core). 3 data_flow items. 4 extension_points. Registered in selected_benchmark_tasks.json and docgen_2config.sh."
     },
     {
       "id": "US-003",

ralph-gapfill-docgen/progress.txt

@@ -34,3 +34,24 @@
   - The investigation task test.sh (inv-debug-001) is the closest template for docgen verifiers — same Python scoring engine
   - docgen_2config.sh has two arrays to populate: ALL_TASK_IDS and TASK_SG_REPO_NAMES
 ---
+
+## 2026-02-16 - US-002
+- Created docgen-arch-002: Istio Pilot Discovery Service architecture doc task
+- Files created:
+  - benchmarks/ccb_docgen/docgen-arch-002/task.toml (category=architecture_doc, language=go, difficulty=hard, time_limit_sec=1200)
+  - benchmarks/ccb_docgen/docgen-arch-002/instruction.md (covers DiscoveryServer, ADS, PushContext, ServiceRegistry, multi-cluster support)
+  - benchmarks/ccb_docgen/docgen-arch-002/tests/ground_truth.json (13 required_topics, 5 file_references, 3 data_flow, 4 extension_points)
+  - benchmarks/ccb_docgen/docgen-arch-002/tests/test.sh (copied from docgen-arch-001, generic Python-based verifier)
+  - benchmarks/ccb_docgen/docgen-arch-002/environment/Dockerfile (blobless clone of istio/istio at commit f8af3cae)
+- Files modified:
+  - configs/docgen_2config.sh (added docgen-arch-002 to ALL_TASK_IDS and TASK_SG_REPO_NAMES)
+  - configs/selected_benchmark_tasks.json (registered task with mcp_benefit_score=0.860, total_selected: 190→191)
+- **Learnings for future iterations:**
+  - Istio Pilot architecture has 4 key layers: DiscoveryServer (xDS gRPC), ADS (connection model), PushContext (config snapshot), ServiceRegistry (K8s + multi-cluster)
+  - Used WebSearch and WebFetch to research Istio architecture before writing ground truth
+  - Found specific commit (f8af3caeb1) from GitHub's master branch via WebFetch
+  - Ground truth covers pilot/pkg/xds/ (discovery.go, ads.go), pilot/pkg/model/push_context.go, pilot/pkg/serviceregistry/kube/controller/
+  - Same 4-category scoring pattern as docgen-arch-001: required_topics (0.40), file_references (0.25), data_flow (0.20), extension_points (0.15)
+  - MCP advantage higher for Istio (0.860) than Envoy (0.855) due to more cross-file dependencies (0.92 vs 0.90)
+  - test.sh is reusable across all docgen architecture tasks — just copy from docgen-arch-001
+---