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ln-813-runtime-optimizer

Type: L3 Worker Category: 8XX Optimization Parent: ln-810-performance-optimization-coordinator

Fixes runtime performance issues found by ln-653-runtime-performance-auditor. Each fix verified via tests + lint with keep/discard pattern.

Overview

Aspect Details

Input Audit findings from docs/project/persistence_audit.md (ln-653 section) OR target file

Output Optimized code, verification report

Companion ln-653-runtime-performance-auditor (finds issues) → ln-813 (fixes them)

Workflow

Phases: Pre-flight → Load Findings → Prioritize → Fix Loop → Report

Phase 0: Pre-flight Checks

Check Required Action if Missing

Audit findings OR target file Yes Block optimization

Test infrastructure Yes Block (need tests for verification)

Linter available No Skip lint step in verification

Git clean state Yes Block (need clean baseline for revert)

MANDATORY READ: Load shared/references/ci_tool_detection.md — use Test Frameworks + Linters sections.

Worktree & Branch Isolation

MANDATORY READ: Load shared/references/git_worktree_fallback.md — use ln-813 row.

Phase 1: Load Findings

From Audit Report

Read docs/project/persistence_audit.md , extract ln-653 findings:

Finding Type Optimization

Blocking IO in async asyncio.to_thread() , aiofiles , async HTTP client

String concat in loop StringBuilder (.NET), "".join() (Python), template literals (JS)

Unnecessary allocations Pre-allocate collections, object pooling, Span<T>

Sync sleep in async asyncio.sleep() , Task.Delay() , setTimeout

Redundant serialization Cache serialized form, avoid round-trip JSON in memory

From Target File

If no audit report: scan target file for runtime patterns matching the table above.

Phase 2: Prioritize Fixes

Priority Criteria

1 (highest) Blocking IO in async context (blocks event loop)

2 Sync sleep in async (starves thread pool)

3 Allocations in hot loop (GC pressure)

4 String concatenation patterns

5 Other micro-optimizations

Phase 3: Fix Loop (Keep/Discard)

Per-Fix Cycle

FOR each finding (F1..FN):

1. APPLY: Edit code (surgical change)
2. VERIFY: Run tests IF tests FAIL → DISCARD (revert) → next finding
3. VERIFY: Run lint (if available) IF lint FAIL → DISCARD (revert) → next finding
4. BOTH PASS → KEEP
5. LOG: Record fix for report

Keep/Discard Decision

Condition Decision

No tests cover affected file/function SKIP finding — log as "uncovered, skipped"

Tests + lint pass KEEP

Tests fail DISCARD + log reason

Lint fail (new warnings) DISCARD + log reason

Lint unavailable KEEP (tests sufficient)

Phase 4: Report Results

Report Schema

Field Description

source Audit report path or target file

findings_total Total findings from audit

fixes_applied Successfully kept fixes

fixes_discarded Failed fixes with reasons

fix_details[] Per-fix: finding type, file, before/after description

Configuration

Options:

Source

audit_report: "docs/project/persistence_audit.md" target_file: ""

Verification

run_tests: true run_lint: true

Scope

fix_types: - blocking_io - sync_sleep - unnecessary_alloc - string_concat - redundant_serialization

Error Handling

Error Cause Solution

No audit findings ln-653 not run or no issues Report "no findings to optimize"

Async rewrite complex Deep call chain affected Log as manual step, skip

Framework-specific pattern Unknown async framework Query Context7/Ref for docs

References

• ../ln-653-runtime-performance-auditor/SKILL.md (companion: finds issues)

• shared/references/ci_tool_detection.md (test + lint detection)

Definition of Done

• Findings loaded from audit report or target file scan

• Fixes prioritized (blocking IO first, then sync sleep, allocations, string concat)

• Each fix applied with keep/discard: tests + lint pass → keep, either fails → discard

• Report returned with findings total, fixes applied, fixes discarded

Version: 1.0.0 Last Updated: 2026-03-08