P3.1 TaskStore trait + SQLite backend (tables 1-7) - Final verification summary

All 14 tests pass, covering CRUD operations for tables 1-7:
- tasks (Miroir task registry)
- node_settings_version
- aliases (single and multi-target)
- sessions (read-your-writes pins)
- idempotency_cache (BLOB for body_sha256)
- jobs (claim semantics with heartbeat)
- leader_lease (advisory lock for SQLite)

Acceptance criteria met:
✓ Every CRUD round-trips correctly
✓ Idempotent migrations (schema version check)
✓ Concurrent writes don't deadlock (WAL mode + busy_timeout)
✓ Schema designed for 100MB task registry cache

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

notes/miroir-r3j.1-final-summary.md

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+# P3.1 TaskStore trait + SQLite backend (tables 1-7) - Final Summary
+
+## Task Overview
+Implement the TaskStore trait in miroir-core and SQLite backend for the first 7 tables from plan §4 "Task store schema".
+
+## Tables Implemented (1-7)
+
+1. **tasks** — Miroir task registry
+   - JSON node_tasks field using serde_json::Value
+   - Full CRUD operations with status updates
+   - Error tracking support
+
+2. **node_settings_version**
+   - Per-(index, node) settings freshness tracking
+   - Composite primary key (index_uid, node_id)
+   - Timestamp tracking for updates
+
+3. **aliases**
+   - Single and multi-target alias support
+   - JSON array for target_uids (multi-target)
+   - History tracking with retention bounds
+   - Atomic flip operations via upsert
+
+4. **sessions**
+   - Read-your-writes session pins
+   - Group pinning with min_settings_version
+   - TTL-based expiry
+   - Nullable last_write_mtask_id and last_write_at
+
+5. **idempotency_cache**
+   - BLOB for body_sha256 (32 raw bytes)
+   - Write deduplication
+   - TTL-based expiry with pruning
+
+6. **jobs**
+   - Background job queue with claim semantics
+   - claim_expires_at updated by heartbeat (10s)
+   - Progress tracking via JSON field
+   - State transitions: queued → in_progress → completed/failed
+
+7. **leader_lease**
+   - Advisory-lock substitute for SQLite
+   - Holder identification with expiry
+   - Used for singleton-coordinator coordination
+
+## Implementation Details
+
+### Schema Initialization
+- Idempotent migrations using `CREATE TABLE IF NOT EXISTS`
+- Schema version tracking in `schema_version` table
+- WAL mode enabled for better concurrency
+- PRAGMA busy_timeout = 5000 to avoid deadlocks
+
+### Type Safety
+- Custom enums for TaskStatus, AliasKind, JobState
+- Proper Display/FromStr implementations for all enums
+- JSON serialization for complex fields (node_tasks, target_uids, history, progress)
+- BLOB type for binary data (body_sha256, api_key_hash)
+
+### Concurrency
+- Arc<Mutex<Connection>> for shared access
+- Transaction support for job dequeue (claim operation)
+- WAL mode allows concurrent readers
+- 5-second busy timeout prevents deadlocks
+
+## Test Coverage
+
+All 14 tests pass:
+- ✅ test_initialize_schema - Schema version tracking and idempotent initialization
+- ✅ test_tasks_crud - Full CRUD operations for tasks table
+- ✅ test_node_settings_version - Version tracking per (index, node)
+- ✅ test_aliases_single_target - Single-target alias operations
+- ✅ test_aliases_multi_target - Multi-target alias operations
+- ✅ test_sessions - Session upsert, get, delete operations
+- ✅ test_idempotency_cache - Cache check, record, and prune
+- ✅ test_jobs - Job enqueue, dequeue, status updates
+- ✅ test_leader_lease - Lease acquisition, renewal, release
+- ✅ test_concurrent_writes - 10 concurrent task insertions without deadlock
+- ✅ test_health_check - Database health verification
+- ✅ test_persistence - Data survives DB close/reopen
+- ✅ test_task_with_error - Error field serialization
+- ✅ test_task_filter_by_status - Filtering and pagination
+
+## Acceptance Criteria Met
+
+1. ✅ **CRUD operations** - Every table round-trips correctly
+2. ✅ **Idempotent migrations** - Opening existing DB doesn't re-run migrations
+3. ✅ **Concurrent writes** - WAL mode + busy_timeout prevents deadlocks
+4. ✅ **Table size budget** - Schema designed for 100MB task registry cache
+
+## Files Modified
+
+- `crates/miroir-core/src/task_store/mod.rs` - Trait definition and exports
+- `crates/miroir-core/src/task_store/schema.rs` - All 14 table schemas
+- `crates/miroir-core/src/task_store/sqlite.rs` - SQLite backend implementation
+- `crates/miroir-core/src/task_store/sqlite_tests.rs` - Comprehensive test suite
+- `crates/miroir-core/src/task_store/error.rs` - Error types
+- `crates/miroir-core/Cargo.toml` - Dependencies (rusqlite, tokio, async-trait)
+
+## Verification
+
+```bash
+cargo test -p miroir-core --features task-store --lib task_store::sqlite_tests
+```
+
+All 14 tests pass in 0.06s.
+
+## Notes
+
+- Tables 8-14 (canaries, cdc_cursors, tenant_map, etc.) are defined in schema.rs
+  but will be implemented alongside their respective Phase 5 features
+- Redis backend is stubbed but not yet implemented
+- The trait is defined in miroir-core (not miroir-proxy) to allow consumption by
+  miroir-ctl for diagnostics without pulling in the proxy binary