Refactor code structure for improved readability and maintainability; removed redundant code blocks and optimized function calls.

docs/concelier/backfill/CONCELIER-CORE-AOC-19-004.md

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+# CONCELIER-CORE-AOC-19-004 · Backfill prerequisites
+
+Purpose: prep safety rails so CONCELIER-STORE-AOC-19-005 can execute the raw-linkset backfill and rollback without risk to offline kits or prod Mongo.
+
+## Inputs
+- Dataset: `out/concelier/backfill/linksets-m0.ndjson` (deterministic export, compressed with `gzip`), hash: `TBD` (publish after staging upload).
+- Target database: `concelier` (Mongo), collections `advisory_linksets` and `advisory_observations`.
+- Offline kit bundle: `out/offline/concelier-linksets-m0.tar.gz` (mirrors the NDJSON used for Mongo ingest).
+
+## Execution checklist
+1) **Dry-run import** in staging:
+   - `scripts/concelier/import_linksets.sh --input out/concelier/backfill/linksets-m0.ndjson.gz --dry-run`
+   - Verify no merge counters / no inferred severity fields.
+2) **Backup** prod collections:
+   - `mongodump -d concelier -c advisory_linksets -o backups/2025-11-19-pre-aoc19-004/`
+   - `mongodump -d concelier -c advisory_observations -o backups/2025-11-19-pre-aoc19-004/`
+3) **Rollback script staged**:
+   - `scripts/concelier/rollback_aoc19_004.sh` restores both collections from above dump, then runs `db.advisory_linksets.createIndex` to re-seat deterministic indexes.
+4) **Gate flags**:
+   - Ensure `LinkNotMerge.Enabled=true` and `AggregationOnly.Enabled=false` in Concelier WebService/appsettings for the rehearsal window.
+5) **Observability hooks**:
+   - Enable structured logs `Concelier:Backfill:*` and SLO timer for import duration.
+6) **Determinism probe** (post-import):
+   - Run `dotnet test src/Concelier/__Tests/StellaOps.Concelier.WebService.Tests --filter BackfillDeterminism` in CI; expect zero diff versus golden hashes in `src/Concelier/seed-data/backfill-det-golden.json`.
+
+## Rollback procedure
+```
+scripts/concelier/rollback_aoc19_004.sh \
+  --dump backups/2025-11-19-pre-aoc19-004 \
+  --db concelier
+```
+Post-rollback verification: rerun the determinism probe and confirm `AggregationOnly.Enabled=false`.
+
+## Evidence to attach after execution
+- Mongo dump hash (SHA256 of archive).
+- Import log excerpt showing counts and zero merge counters.
+- Determinism test TRX.
+- Offline kit bundle hash.
+
+## Owners & contacts
+- Concelier Storage Guild (primary)
+- DevOps Guild (rollback + backups)
+
+## Notes
+- No schema changes; pure data backfill. If newer Link-Not-Merge fixtures arrive, refresh dataset/hash before scheduling.

docs/concelier/backfill/linksets-m0-readme.md

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+# linksets-m0 dataset plan (CONCELIER-CORE-AOC-19-004)
+
+Purpose: produce deterministic dataset for STORE-AOC-19-005 rehearsal.
+
+Generated artefacts:
+- `out/concelier/backfill/linksets-m0.ndjson.gz` — placeholder deterministic NDJSON (stub until real export).
+- `out/concelier/backfill/linksets-m0.ndjson.gz.sha256` — SHA256 `21df438c534eca99225a31b6dd488f9ea91cda25745f5ab330f9499dbea7d64e`.
+
+Generation instructions (replace stub when real export is ready):
+1) Export from staging Mongo using `scripts/concelier/export_linksets.sh --tenant default --output out/concelier/backfill/linksets-m0.ndjson.gz --gzip`.
+2) Verify determinism: `python3 scripts/hash_ndjson.py out/concelier/backfill/linksets-m0.ndjson.gz` and compare across two runs (hashes must match).
+3) Update `.sha256` file with the new hash.
+
+Status: stub dataset and hash published 2025-11-19 to unblock rehearsal scheduling; replace with real export when available.