Contributor Analyzer

Unified skill for engineering contributor analysis. Combines annual review generation, historical progress tracking, production ownership mapping, and qualitative judgment — all driven by reading actual commit diffs.

Skill Format

Each reference file covers one analysis concern:

Quick Reference: Summary tables and key thresholds
Process Steps: Bash commands and orchestration
Templates: Output formats for reports and profiles
Deep Dive: Full context with examples from real-world 1,091-commit analysis

Impact ratings: CRITICAL (blocks accuracy), HIGH (major insight), MEDIUM (enriches analysis)

When to Apply

Reference these guidelines when:

Running annual or quarterly performance reviews
Assessing promotion readiness with evidence
Tracking contributor progress over time (incremental updates)
Mapping production code ownership and risk
Comparing multiple engineers for team decisions
Identifying single points of failure in codebase ownership

Priority-Ordered References

| Priority | Reference | Impact | Description | |----------|-----------|--------|-------------| | 1 | agent-context-management.md | CRITICAL | Batch sizing, file-based output, context budget | | 2 | annual-review-process.md | CRITICAL | 7-phase analysis: identity, metrics, diffs, bugs, quality, report, comparison | | 3 | accuracy-analysis.md | HIGH | Bug introduction detection, accuracy rate calculation, benchmarks | | 4 | code-quality-catalog.md | HIGH | Anti-pattern catalog (9 patterns) and strength catalog (8 patterns) | | 5 | qualitative-judgment.md | HIGH | Engineering wisdom, situational decisions, growth trajectory | | 6 | report-templates.md | HIGH | Report sections, rating scale, promotion framework, comparison format | | 7 | production-ownership.md | MEDIUM | Production branch ownership, domain map, SPOF detection | | 8 | historical-progress.md | MEDIUM | Incremental profiles, plateau detection, period-over-period tracking |

Quick Reference

Critical: Context Management

Before launching ANY analysis, count commits:

git log --author="EMAIL" --after="YEAR-01-01" --before="YEAR+1-01-01" --oneline | wc -l

Batch sizing (hard limits from real failures):

| Commits | Action | |---------|--------| | 1-40 | Read in main session | | 41-70 | Single sub-task, writes findings to file | | 71-90 | Split into 2 sub-tasks | | 91+ | WILL FAIL — split into 3+ or monthly sub-tasks |

Sub-tasks write to files, return 3-line summaries. Never return raw analysis inline.

Critical: Annual Review Process

7 phases, sequential:

Identity Discovery — find all git email variants
Metrics — commits, PRs, reviews, lines (git + gh CLI)
Read ALL Diffs — quarterly parallel sub-tasks, file-based output
Bug Introduction — self-reverts, crash-fixes, same-day fixes, hook bypass
Code Quality — anti-patterns and strengths from diff reading
Report Generation — structured markdown with rating + promotion assessment
Comparison — multi-engineer ranking with evidence

High: Accuracy Rate

Effective Accuracy = 100% - (fix-related commits / total commits)

| Rate | Assessment | |------|-----------| | >90% | Excellent | | 85-90% | Good | | 80-85% | Concerning | | <80% | Poor — significant rework |

High: Tool Separation

Local git: ALL commit-level analysis (log, show, diff, blame, shortlog)
gh CLI: ONLY for PR counts, review counts, user verification
Never use gh to read diffs — local git is faster with no rate limits

References

Full documentation with process steps and templates in references/:

Analysis Process

| File | Impact | Description | |------|--------|-------------| | annual-review-process.md | CRITICAL | Complete 7-phase review process with bash commands | | agent-context-management.md | CRITICAL | Batch sizing, file-based output, multi-engineer orchestration | | accuracy-analysis.md | HIGH | Bug detection commands, accuracy formula, benchmarks | | code-quality-catalog.md | HIGH | 9 anti-patterns + 8 strengths with severity/significance |

Judgment & Assessment

| File | Impact | Description | |------|--------|-------------| | qualitative-judgment.md | HIGH | Engineering wisdom indicators, growth trajectory, promotion signals | | report-templates.md | HIGH | Required report sections, rating scale, comparison format |

Ownership & Progress

| File | Impact | Description | |------|--------|-------------| | production-ownership.md | MEDIUM | Production file identification, domain map, SPOF detection | | historical-progress.md | MEDIUM | Incremental profiles, plateau detection, cumulative profiles |

Searching References

# Find by keyword
grep -rl "accuracy" references/
grep -rl "promotion" references/
grep -rl "ownership" references/
grep -rl "anti-pattern" references/

Problem to Reference Mapping

| Problem | Start With | |---------|------------| | Annual review for 1 engineer | annual-review-process.md then report-templates.md | | Comparing 2+ engineers for promotion | annual-review-process.md then qualitative-judgment.md | | Engineer has 200+ commits | agent-context-management.md (read FIRST) | | Session keeps running out of context | agent-context-management.md | | Is this engineer ready for promotion? | qualitative-judgment.md then accuracy-analysis.md | | Who owns the payment system? | production-ownership.md | | Track progress since last review | historical-progress.md | | Quality assessment from code | code-quality-catalog.md then accuracy-analysis.md | | Single points of failure in team | production-ownership.md | | Plateau detection | historical-progress.md |

Full Compiled Document

For the complete guide with all references expanded: AGENTS.md

Usage Examples

# Annual review (single engineer)
Analyze @alice for 2025 annual review in repo org/repo.
Git email: alice@company.com. Write to ./alice-2025-review.md

# Multi-engineer comparison with promotion decision
Analyze @alice, @bob, @charlie for 2025 reviews.
I need to decide which 2 get promoted.

# Production ownership mapping
Analyze production code ownership in this repo.

# Incremental progress update
Update @alice's progress profile with latest contributions.

# Critical path risk detection
Find single points of failure in production code ownership.

# Plateau detection
Has @bob plateaued? Check last 3 quarters.