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Transaction Correctness Auditor (L3 Worker)

Specialized worker auditing database transaction patterns for correctness, scope, and trigger interaction.

Purpose & Scope

• Worker in ln-650 coordinator pipeline – invoked by ln-650-persistence-performance-auditor
• Audit transaction correctness (Priority: HIGH)
• Check commit patterns, transaction boundaries, rollback handling, trigger/notify semantics
• Return structured findings with severity, location, effort, recommendations
• Calculate compliance score (X/10) for Transaction Correctness category

Inputs (from Coordinator)

MANDATORY READ: Load shared/references/task_delegation_pattern.md#audit-coordinator--worker-contract for contextStore structure.

Receives contextStore with: tech_stack, best_practices, db_config (database type, ORM settings, trigger/notify patterns), codebase_root.

Domain-aware: Supports domain_mode + current_domain.

Workflow

1. Parse context from contextStore

   • Extract tech_stack, best_practices, db_config
   • Determine scan_path

2. Discover transaction infrastructure

   • Find migration files with triggers (pg_notify, CREATE TRIGGER, NOTIFY)
   • Find session/transaction configuration (expire_on_commit, autocommit, isolation level)
   • Map trigger-affected tables

3. Scan codebase for violations

   • Trace UPDATE paths for trigger-affected tables
   • Analyze transaction boundaries (begin/commit scope)
   • Check error handling around commits

4. Collect findings with severity, location, effort, recommendation

5. Calculate score using penalty algorithm

6. Return JSON result to coordinator

Audit Rules (Priority: HIGH)

1. Missing Intermediate Commits

What: UPDATE without commit when DB trigger/NOTIFY depends on transaction commit

Detection:

• Step 1: Find triggers in migrations:
  • Grep for pg_notify|NOTIFY|CREATE TRIGGER|CREATE OR REPLACE FUNCTION.*trigger in alembic/versions/, migrations/
  • Extract: trigger function name, table name, trigger event (INSERT/UPDATE)
• Step 2: Find code that UPDATEs trigger-affected tables:
  • Grep for repo.*update|session\.execute.*update|\.progress|\.status related to trigger tables
• Step 3: Check for commit() between sequential updates:
  • If multiple UPDATEs to trigger table occur in a loop/sequence without intermediate commit(), NOTIFY events are deferred until final commit
  • Real-time progress tracking breaks without intermediate commits

Severity:

• CRITICAL: Missing commit for NOTIFY/LISTEN-based real-time features (SSE, WebSocket)
• HIGH: Missing commit for triggers that update materialized data

Recommendation:

• Add session.commit() at progress milestones (throttled: every N%, every T seconds)
• Or move real-time notifications out of DB triggers (Redis pub/sub, in-process events)

Effort: S-M (add strategic commits or redesign notification path)

2. Transaction Scope Too Wide

What: Single transaction wraps unrelated operations, including slow external calls

Detection:

• Find async with session.begin() or explicit transaction blocks
• Check if block contains external calls: await httpx., await aiohttp., await requests., await grpc.
• Check if block contains file I/O: open(, .read(, .write(
• Pattern: DB write + external API call + another DB write in same transaction

Severity:

• HIGH: External HTTP/gRPC call inside transaction (holds DB connection during network latency)
• MEDIUM: File I/O inside transaction

Recommendation: Split into separate transactions; use Saga/Outbox pattern for cross-service consistency

Effort: M-L (restructure transaction boundaries)

3. Transaction Scope Too Narrow

What: Logically atomic operations split across multiple commits

Detection:

• Multiple session.commit() calls for operations that should be atomic
• Pattern: create parent entity, commit, create child entities, commit (should be single transaction)
• Pattern: update status + create audit log in separate commits

Severity:

• HIGH: Parent-child creation in separate commits (orphan risk on failure)
• MEDIUM: Related updates in separate commits (inconsistent state on failure)

Recommendation: Wrap related operations in single transaction using async with session.begin() or unit-of-work pattern

Effort: M (restructure commit boundaries)

4. Missing Rollback Handling

What: session.commit() without proper error handling and rollback

Detection:

• Find session.commit() not inside try/except block or context manager
• Find session.commit() in try without session.rollback() in except
• Pattern: bare await session.commit() in service methods
• Exception: async with session.begin() auto-rollbacks (safe)

Severity:

• MEDIUM: Missing rollback (session left in broken state on failure)
• LOW: Missing explicit rollback when using context manager (auto-handled)

Recommendation: Use async with session.begin() (auto-rollback), or add explicit try/except/rollback pattern

Effort: S (wrap in context manager or add error handling)

5. Long-Held Transaction

What: Transaction open during slow/blocking operations

Detection:

• Measure scope: count lines between transaction start and commit
• Flag if >50 lines of code between begin() and commit()
• Flag if transaction contains await calls to external services (network latency)
• Flag if transaction contains time.sleep() or asyncio.sleep()

Severity:

• HIGH: Transaction held during external API call (connection pool exhaustion risk)
• MEDIUM: Transaction spans >50 lines (complex logic, high chance of lock contention)

Recommendation: Minimize transaction scope; prepare data before opening transaction, commit immediately after DB operations

Effort: M (restructure code to minimize transaction window)

Scoring Algorithm

MANDATORY READ: Load shared/references/audit_scoring.md for unified scoring formula.

Output Format

Return JSON to coordinator:

{
  "category": "Transaction Correctness",
  "score": 5,
  "total_issues": 6,
  "critical": 1,
  "high": 2,
  "medium": 2,
  "low": 1,
  "findings": [
    {
      "severity": "CRITICAL",
      "location": "app/infrastructure/messaging/job_processor.py:412",
      "issue": "Missing intermediate commits: progress UPDATEs trigger pg_notify but no commit() between updates; real-time SSE events deferred",
      "principle": "Transaction Correctness / Trigger Semantics",
      "recommendation": "Add session.commit() at progress milestones (throttled every 5%)",
      "effort": "S"
    }
  ]
}

Critical Rules

• Do not auto-fix: Report only
• Trigger discovery first: Always scan migrations for triggers/NOTIFY before analyzing transaction patterns
• ORM-aware: Check if ORM context manager auto-rollbacks (async with session.begin() is safe)
• Exclude test transactions: Do not flag test fixtures with manual commit/rollback
• Database-specific: PostgreSQL NOTIFY semantics differ from MySQL event scheduler

Definition of Done

• contextStore parsed (tech_stack, db_config, trigger patterns)
• scan_path determined
• Trigger/NOTIFY infrastructure discovered from migrations
• All 5 checks completed:
  • missing intermediate commits, scope too wide, scope too narrow, missing rollback, long-held
• Findings collected with severity, location, effort, recommendation
• Score calculated
• JSON returned to coordinator

Reference Files

• Audit scoring formula: shared/references/audit_scoring.md
• Audit output schema: shared/references/audit_output_schema.md

Version: 1.0.0 Last Updated: 2026-02-04