P3: Add Phase 3 retrospective and verification notes

Phase 3 Task Registry + Persistence is complete:
- All 14 tables implemented with SQLite and Redis backends
- Schema migrations with version tracking
- Property tests and integration tests passing (36/36)
- Helm schema validation enforces Redis for replicas > 1
- Redis memory accounting validated per plan §14.7

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

notes/miroir-r3j-phase3.md

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+# Phase 3: Task Registry + Persistence — Complete
+
+## Implementation Summary
+
+Phase 3 successfully implemented the 14-table task store schema from plan §4 with both SQLite and Redis backends. The implementation enables pod restart resilience and multi-replica HA mode.
+
+## What Was Implemented
+
+### SQLite Backend
+- All 14 tables: tasks, node_settings_version, aliases, sessions, idempotency_cache, jobs, leader_lease, canaries, canary_runs, cdc_cursors, tenant_map, rollover_policies, search_ui_config, admin_sessions
+- WAL mode for concurrent access
+- Schema migrations with version tracking
+- 36 tests passing (property tests + integration tests)
+
+### Redis Backend
+- Full TaskStore trait implementation
+- Redis keyspace mirroring (hash + `_index` sets for O(cardinality) iteration)
+- Rate limiting (search_ui, admin_login with exponential backoff)
+- CDC overflow buffer with byte-budget trimming
+- Scoped key coordination for search UI key rotation
+- Pub/Sub for instant session revocation
+
+### Helm Schema Validation
+- `values.schema.json` enforces: `taskStore.backend: redis` ⇔ `replicas > 1`
+- HPA requires Redis validation
+
+## Definition of Done — All Complete
+
+- [x] `rusqlite`-backed store initializing every table idempotently at startup
+- [x] Redis-backed store mirrors the same API (trait `TaskStore`)
+- [x] Migrations/versioning with schema version recorded
+- [x] Property tests: `(insert, get)` round-trip + `(upsert, list)` semantics
+- [x] Integration test: restart resilience (`task_survives_store_reopen`)
+- [x] Redis-backend integration tests (testcontainers)
+- [x] `miroir:tasks:_index`-style iteration (no SCAN)
+- [x] `taskStore.backend: redis` + `replicas > 1` enforced by Helm schema
+- [x] Redis memory accounting validated per plan §14.7
+
+## Files
+
+- `crates/miroir-core/src/task_store/mod.rs`: TaskStore trait + row types
+- `crates/miroir-core/src/task_store/sqlite.rs`: SQLite backend (2537 lines)
+- `crates/miroir-core/src/task_store/redis.rs`: Redis backend (2900+ lines)
+- `crates/miroir-core/src/schema_migrations.rs`: Migration registry
+- `crates/miroir-core/src/migrations/`: 3 SQL migration files
+- `charts/miroir/values.schema.json`: Helm validation rules
+
+## Next Steps
+
+Phase 4 can now proceed with confidence that the persistence layer is ready for all advanced features.