chore: update progress.txt with US-014 learnings

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: sjarmak

ralph-mcp-unique/progress.txt

@@ -325,3 +325,27 @@
   - file_set_match + provenance: file coverage + citation verification (text must mention file path and repo)
   - pkg/dataobj/explorer/service.go confirmed via direct read_file: 4 endpoints, no middleware wrapping
 ---
+[2026-02-20 20:57:58 UTC] Iteration 4 no story markers found
+[2026-02-20 20:57:58 UTC] Iteration 4 complete
+[2026-02-20 20:58:00 UTC] Iteration 5 started
+
+## 2026-02-20 - US-014: Starter tasks — Category D: Incident debugging (1 task)
+- Authored 1 complete task in benchmarks/ccb_mcp_incident/:
+
+**CCX-incident-031** (D31 — error to code path, multi-org-go fixture):
+  - Scenario: on-call SRE traces Kubernetes watch-stream error "etcdserver: mvcc: required revision has been compacted" to authoritative etcd source
+  - Oracle: {etcd-io/etcd, server/storage/mvcc/kvstore.go, ErrCompacted} + {etcd-io/etcd, server/storage/mvcc/kvstore_txn.go, rangeKeys}
+  - Decoy design: kubernetes/kubernetes has vendored copies at vendor/go.etcd.io/etcd/server/v3/storage/mvcc/kvstore.go + apiserver error-mapping at staging/src/k8s.io/apiserver/pkg/storage/etcd3/errors.go — instruction explicitly warns about these to test precision
+  - eval.sh: file_set_match (oracle files must match) + keyword_presence ("ErrCompacted", "rangeKeys")
+  - Validity gate: VALID (gold=1.0, empty=0.0)
+  - Registered in configs/selected_mcp_unique_tasks.json (6 tasks total now)
+
+- Files changed: benchmarks/ccb_mcp_incident/ccx-incident-031/ (8 new files), configs/selected_mcp_unique_tasks.json, prd.json
+- **Learnings for future iterations:**
+  - Decoy design principle: use vendored copies in local repo as decoys — they look identical to the real source but are not authoritative
+  - "negative knowledge" in instruction.md (explicitly warning about decoys) creates clearer test of whether agent can distinguish source vs. copy
+  - kubernetes/kubernetes is large (~800MB) so --depth 1 is essential for Dockerfile clone
+  - multi-org-go fixture: kubernetes=local, etcd/grafana=MCP-only — natural for incident debugging where error originates in etcd
+  - Error "mvcc: required revision has been compacted" verified: defined in kvstore.go line 37, returned in kvstore_txn.go line 81 (rangeKeys function)
+  - oracle_checks.py file_set_match matches on (repo, path) tuples — repo must be "etcd-io/etcd" not "github.com/etcd-io/etcd"
+---