Talk Stage 2: Research (REX mode only)

Builds the git proof for a REX talk. Cross-references git history, CHANGELOG, and the Stage 1 summary to produce a verified timeline and velocity analysis.

Automatically skipped in --concept mode — only runs when the source material is a REX with git repository access.

When to Use This Skill

• After Stage 1 (Extract) when building a REX talk
• When you have access to the project's git repository
• To verify metrics mentioned in the source material against actual git data

What This Skill Does

1. Reads the summary — understands the period and themes from Stage 1
2. Git archaeology — extracts velocity metrics (read-only commands only)
3. Changelog analysis — scans releases, features, documented metrics
4. Cross-references — aligns git, CHANGELOG, and summary
5. Builds the timeline — verified dates, not estimated
6. Writes 3 output files

Input

• talks/{YYYY}-{slug}-summary.md (from Stage 1 — required)
• repo_path — absolute path to the git repository
• Optional: CHANGELOG path if different from {repo_path}/CHANGELOG.md

Output

Three files:

• talks/{YYYY}-{slug}-git-archaeology.md
• talks/{YYYY}-{slug}-changelog-analysis.md
• talks/{YYYY}-{slug}-timeline.md

Git Commands (read-only only)

# Commits by month
git -C {repo_path} log --pretty=format:"%Y-%m" | sort | uniq -c

# Commits by contributor
git -C {repo_path} shortlog -sn --no-merges

# First and last date
git -C {repo_path} log --pretty=format:"%ad" --date=short | tail -1
git -C {repo_path} log --pretty=format:"%ad" --date=short | head -1

# Merged PRs (if merge commit convention)
git -C {repo_path} log --merges --oneline | wc -l

# Tags (releases)
git -C {repo_path} tag --sort=version:refname

# Velocity peak (busiest months)
git -C {repo_path} log --pretty=format:"%Y-%m" | sort | uniq -c | sort -rn | head -5

Output Formats

git-archaeology.md

# Git Archaeology — {slug}

**Repo**: {repo_path}
**Period analyzed**: {start date} → {end date}
**Commands run**: {list}

## Global Metrics

| Metric | Value | Source |
|--------|-------|--------|
| Total commits | {n} | git log |
| Total merges/PRs | ~{n} | git log --merges |
| Total releases (tags) | {n} | git tag |
| Human contributors | {n} | git shortlog |
| Period covered | {n} months | first → last date |

## Monthly Velocity

| Month | Commits | Notes |
|-------|---------|-------|
| {YYYY-MM} | {n} | {context if notable} |
...

## Contributors

| Rank | Name | Commits | % |
|------|------|---------|---|
| 1 | {name} | {n} | {%} |
...

---
*Generated by talk-stage2-research — {date}*

changelog-analysis.md

# Changelog Analysis — {slug}

**Source**: {CHANGELOG path}
**Releases analyzed**: {n} (v{first} → v{last})

## Features by release (summary)

| Release | Date | Key features | Metrics mentioned |
|---------|------|--------------|------------------|
| {version} | {date} | {features} | {metrics} |
...

## Patterns identified

### Acceleration
{Periods of high velocity and what drove them}

### Inflection points
{Pivots, direction changes, major releases}

### Verifiable metrics in CHANGELOG
{Exhaustive list of numbers mentioned in CHANGELOG with their release}

---
*Generated by talk-stage2-research — {date}*

timeline.md

# Factual Timeline — {slug}

**Period**: {start} → {end} ({n} months)
**Cross-referenced sources**: Summary × Git history × CHANGELOG

---

## Month-by-month timeline

| Month | Commits | Releases | Versions | Key features | Talk event |
|-------|---------|----------|----------|--------------|-----------|
| {YYYY-MM} | {n} | {n} | {versions} | {features} | {anecdote/event} |
...

## Cross-reference: Conflicts and inconsistencies

{If dates or metrics contradict between sources, note here}

---
*Generated by talk-stage2-research — {date}*
*Sources: git log × {CHANGELOG path} × {summary path}*

Key Rules

• Read-only only — no git commands that modify repo state
• Verify before asserting — a date not found in git = "unverified"
• Cross-reference — flag inconsistencies between sources, don't pick one arbitrarily
• Granularity — month by month minimum; week by week if the period is short (< 2 months)

Anti-patterns

• Running git commands that modify the repository
• Estimating dates instead of verifying them in git
• Rounding metrics without flagging it
• Silently merging contradictory data from different sources
• Omitting quiet periods — plateaus tell a story too

Validation Checklist

• Only read-only git commands executed
• Timeline covers the full period from summary
• All metrics have an explicit source (git or CHANGELOG)
• Conflicts between sources flagged in dedicated section
• 3 files generated and saved

Tips

• The timeline is what Stage 3 (Concepts) uses to enrich concept scores — a good timeline makes the concept catalogue stronger
• "Quiet periods" in git velocity often correspond to hardest engineering challenges — worth noting
• If the CHANGELOG has no version tags, fall back to date-based anchoring

Related

• Stage 1: Extract — prerequisite
• Stage 3: Concepts — reads this timeline
• Orchestrator