Ownership, Tech Debt & Refactoring

Analyzing code ownership patterns, assessing technical debt severity, and identifying refactoring candidates.

Ownership and Knowledge Silo Analysis

Identifying bus-factor risks

Find critical infrastructure code with ownership concentration, metadata only

Tool parameters

{
  "query": "critical infrastructure",
  "rerank": "ownership",
  "metaOnly": true,
  "limit": 30
}

What to look for in results:

Signal	Risk level	Meaning
dominantAuthorPct >= 90 + contributorCount == 1	Critical	Single person wrote and maintains this code
dominantAuthorPct >= 70 + contributorCount == 2	High	One person dominates, one occasional contributor
dominantAuthorPct < 50 + contributorCount >= 4	Low	Distributed ownership, healthy bus factor

Combining ownership with churn

The most dangerous combination: knowledge silo + high churn + high bug-fix rate. One person owns code that keeps breaking.

Find single-owner code with high bug-fix rates in authentication

Tool parameters

{
  "query": "authentication authorization access control",
  "rerank": {
    "custom": {
      "similarity": 0.2,
      "knowledgeSilo": 0.3,
      "bugFix": 0.25,
      "chunkChurn": 0.25
    }
  },
  "pathPattern": "**/auth/**"
}

Action matrix:

Ownership	Churn	Bug Fix Rate	Action
Silo (1 author)	High	High	Immediate risk — schedule pair programming, knowledge transfer
Silo (1 author)	Low	Low	Monitor — stable but still a bus factor
Distributed (4+ authors)	High	High	Quality problem but no knowledge risk
Distributed (4+ authors)	Low	Low	Healthy — no action needed

Tech Debt Assessment: Beyond Age

Tech debt is not just "old code." It's old code that keeps requiring patches. The techDebt preset captures this:

Find legacy code older than 60 days with high churn in core domain, metadata only

Tool parameters

{
  "query": "core domain logic",
  "rerank": "techDebt",
  "filter": {
    "must": [{ "key": "git.ageDays", "range": { "gte": 60 } }]
  },
  "metaOnly": true,
  "limit": 30
}

Scoring tech debt severity

Combine signals to assess severity — not all old code is debt:

Pattern	Severity	Description
ageDays > 180 + commitCount > 15 + bugFixRate > 40%	Critical	Old code that keeps breaking and getting patched
ageDays > 180 + commitCount > 15 + bugFixRate < 15%	Low	Old code that changes for features, not fixes — active evolution
ageDays > 180 + commitCount < 3 + bugFixRate = 0%	None	Old stable code — not debt, just mature
ageDays > 90 + relativeChurn > 5.0 + churnVolatility > 30	High	Code has been substantially rewritten multiple times with irregular bursts

The relativeChurn advantage

Raw commitCount is misleading for debt assessment. A 2000-line utility file with 20 commits might be fine. A 50-line config file with 20 commits (relativeChurn = 8.0+) is a design problem.

Use relativeChurn for debt ranking:

relativeChurn range	Interpretation
< 0.5	Stable, well-designed
0.5 - 2.0	Normal development activity
2.0 - 5.0	Moderate churn — review if bugFixRate is high
> 5.0	Code has been rewritten multiple times — strong debt signal

This aligns with Nagappan & Ball's finding that relative churn is the strongest single defect predictor.

Refactoring Candidates: Size + Churn + Quality

The best refactoring candidates are large functions with high chunk-level churn and high bug-fix rates:

Find large, high-churn request handlers and processors as refactoring candidates

Tool parameters

{
  "query": "request handler processor controller",
  "rerank": "refactoring",
  "metaOnly": true,
  "limit": 20
}

Prioritization criteria

Criterion	Metric	Why it matters
Function size	chunkSize (lines)	Large functions are harder to understand and test
Chunk churn	chunkChurnRatio	If one function absorbs most of the file's churn, it needs splitting
Bug density	chunkBugFixRate	High fix rate = function is structurally fragile
Volatility	churnVolatility	Irregular bursts indicate reactive patching
Relative churn	relativeChurn	Size-normalized — strongest defect predictor

Distinguishing refactoring from tech debt

Tech debt and refactoring overlap but serve different purposes:

Analysis	Focus	Key signal	Goal
Tech debt (techDebt preset)	File age + accumulation	ageDays + commitCount + bugFixRate	Identify legacy code needing modernization
Refactoring (refactoring preset)	Function size + structure	chunkChurnRatio + chunkSize + chunkBugFixRate	Identify specific functions to split or redesign

A 2-month-old 200-line function with 8 bug fixes is a refactoring candidate (young, badly structured) but not tech debt (not old). An 18-month-old file with steady patches is tech debt (accumulated cruft) but refactoring might target only one function within it.