# 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.