# Drift Analysis

> Use when the user asks about plan drift, reality check, comparing docs to code, project state analysis, roadmap alignment, implementation gaps, or needs guidance on identifying discrepancies between documented plans and actual implementation state.

- Skill: `agent-sh/drift-analysis` (Agent Skill)
- Install (CLI): `npx skillmds@latest add agent-sh/drift-analysis`
- Raw SKILL.md: https://api.skillmd.com/api/skills/agent-sh/drift-analysis/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Product & Planning
- Author: agent-sh (https://skillmd.com/u/agent-sh)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/agent-sh/drift-analysis

---


# Drift Analysis

Knowledge and patterns for analyzing project state, detecting plan drift, and creating prioritized reconstruction plans.

## Architecture Overview

```
/drift-detect
        │
        ├─→ collectors.js (pure JavaScript)
        │   ├─ scanGitHubState()
        │   ├─ analyzeDocumentation()
        │   ├─ scanCodebase()
        │   └─ getRepoIntelSignals()  (optional, via agent-analyzer binary)
        │
        └─→ plan-synthesizer (Sonnet)
            └─ Deep semantic analysis with full context
```

**Data collection**: Pure JavaScript (no LLM overhead)
**Semantic analysis**: Single Sonnet call with complete context

## Drift Detection Patterns

### Types of Drift

**Plan Drift**: When documented plans diverge from actual implementation
- PLAN.md items remain unchecked for extended periods
- Roadmap milestones slip without updates
- Sprint/phase goals not reflected in code changes

**Documentation Drift**: When documentation falls behind implementation
- New features exist without corresponding docs
- README describes features that don't exist
- API docs don't match actual endpoints

**Issue Drift**: When issue tracking diverges from reality
- Stale issues that no longer apply
- Completed work without closed issues
- High-priority items neglected

**Scope Drift**: When project scope expands beyond original plans
- More features documented than can be delivered
- Continuous addition without completion
- Ever-growing backlog with no pruning

### Detection Signals

```
HIGH-CONFIDENCE DRIFT INDICATORS:
- Milestone 30+ days overdue with open issues
- PLAN.md < 30% completion after 90 days
- 5+ high-priority issues stale > 60 days
- README features not found in codebase

MEDIUM-CONFIDENCE INDICATORS:
- Documentation files unchanged for 180+ days
- Draft PRs open > 30 days
- Issue themes don't match code activity
- Large gap between documented and implemented features

LOW-CONFIDENCE INDICATORS:
- Many TODOs in codebase
- Stale dependencies
- Old git branches not merged
```

## Prioritization Framework

### Priority Calculation

```javascript
function calculatePriority(item, weights) {
  let score = 0;

  // Severity base score
  const severityScores = {
    critical: 15,
    high: 10,
    medium: 5,
    low: 2
  };
  score += severityScores[item.severity] || 5;

  // Category multiplier
  const categoryWeights = {
    security: 2.0,    // Security issues get 2x
    bugs: 1.5,        // Bugs get 1.5x
    infrastructure: 1.3,
    features: 1.0,
    documentation: 0.8
  };
  score *= categoryWeights[item.category] || 1.0;

  // Recency boost
  if (item.createdRecently) score *= 1.2;

  // Stale penalty (old items slightly deprioritized)
  if (item.daysStale > 180) score *= 0.9;

  return Math.round(score);
}
```

### Time Bucket Thresholds

| Bucket | Criteria | Max Items |
|--------|----------|-----------|
| Immediate | severity=critical OR priority >= 15 | 5 |
| Short-term | severity=high OR priority >= 10 | 10 |
| Medium-term | priority >= 5 | 15 |
| Backlog | everything else | 20 |

### Priority Weights (Default)

```yaml
security: 10     # Security issues always top priority
bugs: 8          # Bugs affect users directly
features: 5      # New functionality
documentation: 3 # Important but not urgent
tech-debt: 4     # Keeps codebase healthy
```

## Cross-Reference Patterns

### Document-to-Code Matching

```javascript
// Fuzzy matching for feature names
function featureMatch(docFeature, codeFeature) {
  const normalize = s => s
    .toLowerCase()
    .replace(/[-_\s]+/g, '')
    .replace(/s$/, ''); // Remove trailing 's'

  const docNorm = normalize(docFeature);
  const codeNorm = normalize(codeFeature);

  return docNorm.includes(codeNorm) ||
         codeNorm.includes(docNorm) ||
         levenshteinDistance(docNorm, codeNorm) < 3;
}
```

### Common Mismatches

| Documented As | Implemented As |
|---------------|----------------|
| "user authentication" | auth/, login/, session/ |
| "API endpoints" | routes/, api/, handlers/ |
| "database models" | models/, entities/, schemas/ |
| "caching layer" | cache/, redis/, memcache/ |
| "logging system" | logger/, logs/, telemetry/ |

## Output Templates

### Drift Report Section

```markdown
## Drift Analysis

### {drift_type}
**Severity**: {severity}
**Detected In**: {source}

{description}

**Evidence**:
{evidence_items}

**Recommendation**: {recommendation}
```

### Gap Report Section

```markdown
## Gap: {gap_title}

**Category**: {category}
**Severity**: {severity}

{description}

**Impact**: {impact_description}

**To Address**:
1. {action_item_1}
2. {action_item_2}
```

### Reconstruction Plan Section

```markdown
## Reconstruction Plan

### Immediate Actions (This Week)
{immediate_items_numbered}

### Short-Term (This Month)
{short_term_items_numbered}

### Medium-Term (This Quarter)
{medium_term_items_numbered}

### Backlog
{backlog_items_numbered}
```

## Best Practices

### When Analyzing Drift

1. **Compare timestamps, not just content**
   - When was the doc last updated vs. last code change?
   - Are milestones dated realistically?

2. **Look for patterns, not individual items**
   - One stale issue isn't drift; 10 stale issues is a pattern
   - One undocumented feature isn't drift; 5 undocumented features is

3. **Consider context**
   - Active development naturally has some drift
   - Mature projects should have minimal drift
   - Post-launch projects often have documentation lag

4. **Weight by impact**
   - User-facing drift matters more than internal
   - Public API drift matters more than implementation details

### When Creating Plans

1. **Be actionable, not exhaustive**
   - Top 5 immediate items, not top 50
   - Each item should be completable in reasonable time

2. **Group related items**
   - "Update authentication docs" not "Update login page docs" + "Update signup docs"

3. **Include success criteria**
   - How do we know this drift item is resolved?

4. **Balance categories**
   - All security first, but don't ignore everything else
   - Mix quick wins with important work

## Pre-check: Ensure Repo-Intel

Before collecting data, check if the repo-intel map exists:

```javascript
const fs = require('fs');
const path = require('path');

const cwd = process.cwd();
const stateDir = ['.claude', '.opencode', '.codex']
  .find(d => fs.existsSync(path.join(cwd, d))) || '.claude';
const mapFile = path.join(cwd, stateDir, 'repo-intel.json');

if (!fs.existsSync(mapFile)) {
  const response = await AskUserQuestion({
    questions: [{
      question: 'Generate repo-intel?',
      description: 'No repo-intel map found. Generating one enables doc-drift and area health analysis. Takes ~5 seconds.',
      options: [
        { label: 'Yes, generate it', value: 'yes' },
        { label: 'Skip', value: 'no' }
      ]
    }]
  });

  if (response === 'yes' || response?.['Generate repo-intel?'] === 'yes') {
    try {
      const pluginRoot = process.env.CLAUDE_PLUGIN_ROOT;
      if (!pluginRoot) throw new Error('CLAUDE_PLUGIN_ROOT not set');
      const { binary } = require(`${pluginRoot}/lib/agentsys`).get();
      const output = binary.runAnalyzer(['repo-intel', 'init', cwd]);
      const stateDirPath = path.join(cwd, stateDir);
      if (!fs.existsSync(stateDirPath)) fs.mkdirSync(stateDirPath, { recursive: true });
      fs.writeFileSync(mapFile, output);
    } catch (e) {
      console.error(`[INFO] repo-intel init skipped: ${e.message}`);
    }
  }
}
```

## Data Collection (JavaScript)

The collectors.js module extracts data without LLM overhead:

### GitHub Data
- Open issues categorized by labels
- Open PRs with draft status
- Milestones with due dates
- Stale items (> 90 days inactive)
- Theme analysis from titles

### Documentation Data
- Parsed README, PLAN.md, CLAUDE.md, CHANGELOG.md
- Checkbox completion counts
- Section analysis
- Feature lists

### Code Data
- Directory structure
- Framework detection
- Test framework presence
- Health indicators (CI, linting, tests)

### Repo-Intel Data (optional - requires agent-analyzer binary and cached map file)
- `docDrift`: Doc files with low code coupling (likely stale, never co-change with code)
- `areas`: Directory-level health - owners, hotspot score, bug-fix rate, health status (healthy/needs-attention/at-risk)

### Analyzer Data (optional - requires agent-analyzer binary and cached map file)

Structural code-fact signals from the slop-precision detectors. Summarized for the agent's context budget (top 20-30 of each category):

- `orphanExports`: symbols exported but never imported - abandoned or scope-dropped features
- `passthroughWrappers`: single-call delegation functions - often indicates an abstraction that didn't land
- `alwaysTrueConditions`: `if (x == x)` / contradictions - bugs or dead branches
- `docDrift`: doc files with low code coupling, already filtered against versioned_docs/fixtures/generated
- `staleDocsSample`: per-doc per-line removed-symbol references - precise doc-drift evidence
- `entryPoints`: binaries, main() functions, framework configs - execution surfaces that don't need prose docs

## Semantic Analysis (Sonnet)

The plan-synthesizer receives all collected data and performs:

1. **Cross-referencing**: Match documented features to implementation
2. **Drift identification**: Find divergence patterns
3. **Gap analysis**: Identify what's missing
4. **Prioritization**: Context-aware ranking
5. **Report generation**: Actionable recommendations

## Example Input/Output

### Collected Data (from collectors.js)

```json
{
  "github": {
    "issues": [...],
    "categorized": { "bugs": [...], "features": [...] },
    "stale": [...]
  },
  "docs": {
    "files": { "README.md": {...}, "PLAN.md": {...} },
    "checkboxes": { "total": 15, "checked": 3 }
  },
  "code": {
    "frameworks": ["Express"],
    "health": { "hasTests": true, "hasCi": true }
  },
  "repoIntel": {
    "docDrift": [{"path": "README.md", "codeCoupling": 0, "lastChanged": "2025-01-15", "changes": 5}],
    "areas": [{"area": "src/auth/", "files": 8, "owners": [...], "hotspotScore": 3.2, "bugFixRate": 0.25, "health": "at-risk"}]
  },
  "analyzer": {
    "available": true,
    "counts": { "staleDocs": 42, "orphanExports": 3, "passthroughWrappers": 1, "alwaysTrueConditions": 0 },
    "orphanExports": [{"action": {"path": "src/legacy.rs", "lines": [12, 25]}, "reason": "fn `legacyHandler` is exported but never imported", "confidence": 0.75}],
    "passthroughWrappers": [{"action": {"path": "src/api.rs", "lines": [45, 48]}, "reason": "Rust `fn get_user(id)` is a single-call passthrough to `fetch_user` with identical args", "confidence": 0.85}],
    "alwaysTrueConditions": [],
    "docDrift": [],
    "staleDocsSample": [{"doc": "README.md", "line": 42, "reference": "legacyHandler", "issue": "symbol-not-found"}],
    "entryPoints": [{"path": "src/main.rs", "name": "main", "kind": "main"}]
  }
}
```

### Analysis Output (from plan-synthesizer)

```markdown
# Reality Check Report

## Executive Summary
Project has moderate drift: 8 stale priority issues and 20% plan completion.
Strong code health (tests + CI) but documentation lags implementation.

## Drift Analysis
### Priority Neglect
**Severity**: high
8 high-priority issues inactive for 60+ days...

## Prioritized Plan
### Immediate
1. Close #45 (already implemented)
2. Update README API section...
```