---
name: ln-25-persistence-auditor
description: "Audits queries, transactions, data-path performance, and persistence resource lifecycle. Use when data correctness or scalability is at risk; not for general performance tuning."
---

# Persistence Auditor

**Goal:** Perform a read-only audit of persistence and data-heavy runtime paths. Connect static candidates to real query, transaction, resource, or consistency mechanisms and avoid claiming performance impact without evidence.

**Execution contract:** Treat the ordered checkbox workflow below as this skill's Definition of Done. Work through every item in order, and mark it complete only when its action and required evidence are complete. `N/A`, skipped, unavailable, or delegated items remain incomplete.
Before returning, apply this skill's verdict, decision, and approval rules to every incomplete item and prepend **Checklist: X/Y complete**<br>**Incomplete: None | section/item — reason; outcome impact; exact next action**; list every incomplete item.

## Tool Routing

| Need | Preferred tool | Use it when | Fallback |
|---|---|---|---|
| Data-layer map | Native file search over manifests, models, mappings, repositories, migrations, queries, cache, queue, and pool configuration | Establishing stores, frameworks, ownership, and scope | Trace from known request, job, or command entrypoints |
| Call paths and resource ownership | Language server or host-native code intelligence | Following service calls, transaction boundaries, async flow, session scopes, and cleanup | Targeted search plus direct inspection of definitions and callers |
| Query behavior | Existing query logs, tracing, ORM diagnostics, and application metrics | Establishing frequency, duplication, timing, rows, and cache behavior | Static query-in-loop and fetch-shape analysis with explicit limits |
| Query plans | Database-native explain tooling on an approved non-production target | A safe read query and representative schema/data are available | Inspect indexes, predicates, joins, statistics assumptions, and generated SQL statically |
| Runtime performance | Existing profiler, benchmark, or repository diagnostic command | Allocation, blocking, loop amplification, or I/O cost needs measurement | Complete static cost path marked as unmeasured |
| Correctness verification | Repository-defined tests, integration environment, and migration checks | Reproducing transaction, retry, consistency, or lifecycle behavior safely | Static failure trace and required verification plan |
| External semantics | Official database, driver, framework, and runtime documentation matching installed versions | Isolation, pooling, cancellation, caching, trigger, or async semantics affect a finding | Primary-source web research; otherwise mark `UNVERIFIED` |

Never connect to production or run mutating diagnostics. `EXPLAIN ANALYZE` executes the statement: use it only for confirmed read-only queries on an approved disposable or non-production target. Do not create indexes, migrate, vacuum, rewrite data, or change pool settings during the audit.

## Evidence Rules

- Query count, duration, rows, plan, lock, or profile evidence is stronger than a static performance suspicion.
- Static evidence can prove correctness and lifecycle defects when the full path is visible, but performance impact must be labeled unmeasured.
- ORM conventions, bounded administrative paths, startup-only work, and intentionally small datasets require context before becoming findings.
- Transaction advice must match the actual database, isolation level, driver, framework, and retry model.
- Recommendations must preserve data integrity and failure semantics, not only reduce latency.

## Checklist

### 1. Establish the Data and Runtime Context

- [ ] Detect databases, ORMs, drivers, caches, queues, schemas, migrations, pools, dependency-injection scopes, and runtime entrypoints in scope.
- [ ] Resolve installed versions, database capabilities, deployment topology, consistency requirements, and expected workload from repository evidence.
- [ ] Identify critical data paths, high-volume paths, streaming paths, scheduled work, and operations that hold transactions or resources across external calls.
- [ ] Read repository instructions and inspect Git state before running diagnostics or interpreting current work.
- [ ] Establish available query logs, metrics, traces, profiles, representative data, test environments, and safe diagnostic permissions.
- [ ] Keep the audit read-only and document every executed query, command, target, and artifact created.

### 2. Audit Query and Cache Efficiency

- [ ] Trace representative paths from entrypoint through business logic to generated query and materialization.
- [ ] Find N+1 behavior, repeated identical fetches, query-in-loop patterns, sequential independent reads, and redundant existence or count queries.
- [ ] Check over-fetching, broad entity loading, unbounded reads, premature materialization, missing pagination, and user-controlled result amplification.
- [ ] Check missing bulk operations, per-row writes, avoidable round trips, fragmented commits, and opportunities for set-based work.
- [ ] Inspect predicates, joins, sort and group operations, index alignment, query-plan assumptions, and statistics only with schema and workload context.
- [ ] Check cache ownership, key design, scope, invalidation, stampede control, negative caching, staleness tolerance, and duplication with database guarantees.
- [ ] Distinguish latency caused by query shape, connection wait, locks, network, serialization, application work, or downstream services before recommending a fix.
- [ ] Measure or clearly label the expected impact; do not present a candidate index or cache as a proven optimization.

### 3. Audit Transactions and Consistency

- [ ] Identify who begins, commits, rolls back, retries, and disposes each transaction and whether ownership matches the business operation.
- [ ] Check atomicity across related writes, early commits, missing rollback, swallowed exceptions, nested transaction behavior, and partial-success states.
- [ ] Find long-held transactions, network or file calls inside transactions, user interaction during locks, and transactions spanning unnecessary computation.
- [ ] Check isolation assumptions, lost updates, write skew, duplicate processing, optimistic or pessimistic locking, and retry safety.
- [ ] Verify idempotency keys, unique constraints, deduplication, outbox or inbox behavior, and at-least-once delivery paths where applicable.
- [ ] Check triggers, notifications, events, and subscribers for naming, commit-time visibility, payload compatibility, ordering, duplicate delivery, and orphan consumers; do not add intermediate commits merely to expose progress if that breaks business atomicity.
- [ ] Check migrations and backfills for transactional behavior, lock duration, mixed-version compatibility, resumability, and failure recovery.
- [ ] Verify recommendations against official semantics for the installed database, driver, and framework when behavior is version-sensitive.

### 4. Audit Runtime and Resource Lifecycle

- [ ] Check blocking database, filesystem, or network I/O in asynchronous paths and synchronous waits that can starve workers or event loops.
- [ ] Check repeated allocation, copying, serialization, string building, conversion, and collection growth on data-heavy loops.
- [ ] Trace sessions, connections, cursors, readers, streams, locks, subscriptions, and temporary files through success, error, timeout, cancellation, and streaming completion.
- [ ] Include consumer abandonment and partial enumeration: generators, async iterators, streaming responses, and client disconnects must release resources even when normal completion never occurs.
- [ ] Check dependency-injection scope against resource lifetime, especially singleton access to scoped state and request resources held by background or streaming work.
- [ ] For background, streaming, or otherwise longer-lived work, verify bounded resource ownership and acquisition at the point of need instead of retaining a shorter-lived session or connection; a passed factory or pool is one valid design, not a universal requirement.
- [ ] Inspect pool size, timeouts, acquisition, validation, recycling, leak evidence, and the total connection budget across replicas, processes, workers, and failover capacity—not only one process's setting.
- [ ] Check cancellation propagation, command timeouts, retry storms, circuit behavior, and cleanup between retry attempts and after abandoned work.
- [ ] Check ORM expiration, lazy loading, detached entities, and implicit autoflush so no query or write occurs outside the intended session or transaction lifetime.
- [ ] Use runtime measurements where available to separate hot paths from low-frequency or bounded code before assigning performance severity.

### 5. Validate Findings and Report

- [ ] Reproduce high-severity correctness defects with a safe test or complete failure trace and performance defects with query, plan, lock, or profile evidence where possible.
- [ ] Filter framework-managed lifecycle, bounded maintenance tasks, fixtures, migrations kept for history, and documented consistency tradeoffs before confirming findings.
- [ ] Deduplicate symptoms that share one root query, transaction boundary, scope mismatch, or pool configuration.
- [ ] Classify findings as `P0`-`P3` based on data corruption, security, outage risk, scalability, latency, resource exhaustion, and recurrence.
- [ ] Include call path, query or resource, evidence, failure or cost mechanism, impact, confidence, and smallest safe remediation.
- [ ] Use `BLOCKED` when a critical data path, database semantic, or required non-production environment cannot be verified without a credible fallback; use `FAIL` for an evidenced unresolved corruption, atomicity, outage, resource-exhaustion risk, required failing gate, or another `P0/P1`; use `CONCERNS` only for evidenced non-blocking risk or material unmeasured uncertainty, and `PASS` only when critical paths are trustworthy with no material finding.
- [ ] Return the verdict with measured and static scope separated, remediation order, limitations, and residual persistence risks.

## Output Contract

```markdown
# Persistence Audit

**Verdict:** PASS | CONCERNS | FAIL | BLOCKED

## Data context and evidence
- Stores, frameworks, versions, and deployment topology
- Critical and measured paths
- Diagnostics, commands, and environments used

## Health summary
| Area | Status | Evidence basis |
|---|---|---|
| Query and cache efficiency | PASS / CONCERNS / FAIL | measured / static |
| Transactions and consistency | PASS / CONCERNS / FAIL | ... |
| Runtime performance | PASS / CONCERNS / FAIL | measured / static |
| Resource lifecycle | PASS / CONCERNS / FAIL | ... |

## Findings
### [P0 | P1 | P2 | P3] Finding title
- Call path, query, transaction, or resource
- Evidence and confidence
- Failure or cost mechanism
- Required change and verification

## Measurement gaps and residual risks
Unmeasured candidates, unavailable environments, and accepted consistency tradeoffs.
```