Retro

Preamble (run first)

_UPD=$(~/.claude/skills/gstack/bin/gstack-update-check 2>/dev/null || .claude/skills/gstack/bin/gstack-update-check 2>/dev/null || true)
[ -n "$_UPD" ] && echo "$_UPD" || true
mkdir -p ~/.gstack/sessions
touch ~/.gstack/sessions/"$PPID"
_SESSIONS=$(find ~/.gstack/sessions -mmin -120 -type f 2>/dev/null | wc -l | tr -d ' ')
find ~/.gstack/sessions -mmin +120 -type f -delete 2>/dev/null || true
_CONTRIB=$(~/.claude/skills/gstack/bin/gstack-config get gstack_contributor 2>/dev/null || true)
_PROACTIVE=$(~/.claude/skills/gstack/bin/gstack-config get proactive 2>/dev/null || echo "true")
_BRANCH=$(git branch --show-current 2>/dev/null || echo "unknown")
echo "BRANCH: $_BRANCH"
echo "PROACTIVE: $_PROACTIVE"
_LAKE_SEEN=$([ -f ~/.gstack/.completeness-intro-seen ] && echo "yes" || echo "no")
echo "LAKE_INTRO: $_LAKE_SEEN"
mkdir -p ~/.gstack/analytics
echo '{"skill":"retro","ts":"'$(date -u +%Y-%m-%dT%H:%M:%SZ)'","repo":"'$(basename "$(git rev-parse --show-toplevel 2>/dev/null)" 2>/dev/null || echo "unknown")'"}'  >> ~/.gstack/analytics/skill-usage.jsonl 2>/dev/null || true

If PROACTIVE is "false", do not proactively suggest gstack skills — only invoke them when the user explicitly asks. The user opted out of proactive suggestions.

If output shows UPGRADE_AVAILABLE <old> <new>: read ~/.claude/skills/gstack/gstack-upgrade/SKILL.md and follow the "Inline upgrade flow" (auto-upgrade if configured, otherwise AskUserQuestion with 4 options, write snooze state if declined). If JUST_UPGRADED <from> <to>: tell user "Running gstack v{to} (just updated!)" and continue.

If LAKE_INTRO is no: Before continuing, introduce the Completeness Principle. Tell the user: "gstack follows the Boil the Lake principle — always do the complete thing when AI makes the marginal cost near-zero. Read more: https://garryslist.org/posts/boil-the-ocean" Then offer to open the essay in their default browser:

open https://garryslist.org/posts/boil-the-ocean
touch ~/.gstack/.completeness-intro-seen

Only run open if the user says yes. Always run touch to mark as seen. This only happens once.

AskUserQuestion Format

ALWAYS follow this structure for every AskUserQuestion call:

1. Re-ground: State the project, the current branch (use the _BRANCH value printed by the preamble — NOT any branch from conversation history or gitStatus), and the current plan/task. (1-2 sentences)
2. Simplify: Explain the problem in plain English a smart 16-year-old could follow. No raw function names, no internal jargon, no implementation details. Use concrete examples and analogies. Say what it DOES, not what it's called.
3. Recommend: RECOMMENDATION: Choose [X] because [one-line reason] — always prefer the complete option over shortcuts (see Completeness Principle). Include Completeness: X/10 for each option. Calibration: 10 = complete implementation (all edge cases, full coverage), 7 = covers happy path but skips some edges, 3 = shortcut that defers significant work. If both options are 8+, pick the higher; if one is ≤5, flag it.
4. Options: Lettered options: A) ... B) ... C) ... — when an option involves effort, show both scales: (human: ~X / CC: ~Y)

Assume the user hasn't looked at this window in 20 minutes and doesn't have the code open. If you'd need to read the source to understand your own explanation, it's too complex.

Per-skill instructions may add additional formatting rules on top of this baseline.

Completeness Principle — Boil the Lake

AI-assisted coding makes the marginal cost of completeness near-zero. When you present options:

• If Option A is the complete implementation (full parity, all edge cases, 100% coverage) and Option B is a shortcut that saves modest effort — always recommend A. The delta between 80 lines and 150 lines is meaningless with CC+gstack. "Good enough" is the wrong instinct when "complete" costs minutes more.
• Lake vs. ocean: A "lake" is boilable — 100% test coverage for a module, full feature implementation, handling all edge cases, complete error paths. An "ocean" is not — rewriting an entire system from scratch, adding features to dependencies you don't control, multi-quarter platform migrations. Recommend boiling lakes. Flag oceans as out of scope.
• When estimating effort, always show both scales: human team time and CC+gstack time. The compression ratio varies by task type — use this reference:

• This principle applies to test coverage, error handling, documentation, edge cases, and feature completeness. Don't skip the last 10% to "save time" — with AI, that 10% costs seconds.

Anti-patterns — DON'T do this:

• BAD: "Choose B — it covers 90% of the value with less code." (If A is only 70 lines more, choose A.)
• BAD: "We can skip edge case handling to save time." (Edge case handling costs minutes with CC.)
• BAD: "Let's defer test coverage to a follow-up PR." (Tests are the cheapest lake to boil.)
• BAD: Quoting only human-team effort: "This would take 2 weeks." (Say: "2 weeks human / ~1 hour CC.")

Contributor Mode

If _CONTRIB is true: you are in contributor mode. You're a gstack user who also helps make it better.

At the end of each major workflow step (not after every single command), reflect on the gstack tooling you used. Rate your experience 0 to 10. If it wasn't a 10, think about why. If there is an obvious, actionable bug OR an insightful, interesting thing that could have been done better by gstack code or skill markdown — file a field report. Maybe our contributor will help make us better!

Calibration — this is the bar: For example, $B js "await fetch(...)" used to fail with SyntaxError: await is only valid in async functions because gstack didn't wrap expressions in async context. Small, but the input was reasonable and gstack should have handled it — that's the kind of thing worth filing. Things less consequential than this, ignore.

NOT worth filing: user's app bugs, network errors to user's URL, auth failures on user's site, user's own JS logic bugs.

To file: write ~/.gstack/contributor-logs/{slug}.md with all sections below (do not truncate — include every section through the Date/Version footer):

# {Title}

Hey gstack team — ran into this while using /{skill-name}:

**What I was trying to do:** {what the user/agent was attempting}
**What happened instead:** {what actually happened}
**My rating:** {0-10} — {one sentence on why it wasn't a 10}

## Steps to reproduce
1. {step}

## Raw output

{paste the actual error or unexpected output here}

## What would make this a 10
{one sentence: what gstack should have done differently}

**Date:** {YYYY-MM-DD} | **Version:** {gstack version} | **Skill:** /{skill}

Slug: lowercase, hyphens, max 60 chars (e.g. browse-js-no-await). Skip if file already exists. Max 3 reports per session. File inline and continue — don't stop the workflow. Tell user: "Filed gstack field report: {title}"

Completion Status Protocol

When completing a skill workflow, report status using one of:

• DONE — All steps completed successfully. Evidence provided for each claim.
• DONE_WITH_CONCERNS — Completed, but with issues the user should know about. List each concern.
• BLOCKED — Cannot proceed. State what is blocking and what was tried.
• NEEDS_CONTEXT — Missing information required to continue. State exactly what you need.

Escalation

It is always OK to stop and say "this is too hard for me" or "I'm not confident in this result."

Bad work is worse than no work. You will not be penalized for escalating.

• If you have attempted a task 3 times without success, STOP and escalate.
• If you are uncertain about a security-sensitive change, STOP and escalate.
• If the scope of work exceeds what you can verify, STOP and escalate.

Escalation format:

STATUS: BLOCKED | NEEDS_CONTEXT
REASON: [1-2 sentences]
ATTEMPTED: [what you tried]
RECOMMENDATION: [what the user should do next]

Detect default branch

Before gathering data, detect the repo's default branch name: gh repo view --json defaultBranchRef -q .defaultBranchRef.name

If this fails, fall back to main. Use the detected name wherever the instructions say origin/<default> below.

/retro — Weekly Engineering Retrospective

Generates a comprehensive engineering retrospective analyzing commit history, work patterns, and code quality metrics. Team-aware: identifies the user running the command, then analyzes every contributor with per-person praise and growth opportunities. Designed for a senior IC/CTO-level builder using Claude Code as a force multiplier.

User-invocable

When the user types /retro, run this skill.

Arguments

• /retro — default: last 7 days
• /retro 24h — last 24 hours
• /retro 14d — last 14 days
• /retro 30d — last 30 days
• /retro compare — compare current window vs prior same-length window
• /retro compare 14d — compare with explicit window

Instructions

Parse the argument to determine the time window. Default to 7 days if no argument given. All times should be reported in the user's local timezone (use the system default — do NOT set TZ).

Midnight-aligned windows: For day (d) and week (w) units, compute an absolute start date at local midnight, not a relative string. For example, if today is 2026-03-18 and the window is 7 days: the start date is 2026-03-11. Use --since="2026-03-11T00:00:00" for git log queries — the explicit T00:00:00 suffix ensures git starts from midnight. Without it, git uses the current wall-clock time (e.g., --since="2026-03-11" at 11pm means 11pm, not midnight). For week units, multiply by 7 to get days (e.g., 2w = 14 days back). For hour (h) units, use --since="N hours ago" since midnight alignment does not apply to sub-day windows.

Argument validation: If the argument doesn't match a number followed by d, h, or w, the word compare, or compare followed by a number and d/h/w, show this usage and stop:

Usage: /retro [window]
  /retro              — last 7 days (default)
  /retro 24h          — last 24 hours
  /retro 14d          — last 14 days
  /retro 30d          — last 30 days
  /retro compare      — compare this period vs prior period
  /retro compare 14d  — compare with explicit window

Step 1: Gather Raw Data

First, fetch origin and identify the current user:

git fetch origin <default> --quiet
# Identify who is running the retro
git config user.name
git config user.email

The name returned by git config user.name is "you" — the person reading this retro. All other authors are teammates. Use this to orient the narrative: "your" commits vs teammate contributions.

Run ALL of these git commands in parallel (they are independent):

# 1. All commits in window with timestamps, subject, hash, AUTHOR, files changed, insertions, deletions
git log origin/<default> --since="<window>" --format="%H|%aN|%ae|%ai|%s" --shortstat

# 2. Per-commit test vs total LOC breakdown with author
#    Each commit block starts with COMMIT:<hash>|<author>, followed by numstat lines.
#    Separate test files (matching test/|spec/|__tests__/) from production files.
git log origin/<default> --since="<window>" --format="COMMIT:%H|%aN" --numstat

# 3. Commit timestamps for session detection and hourly distribution (with author)
git log origin/<default> --since="<window>" --format="%at|%aN|%ai|%s" | sort -n

# 4. Files most frequently changed (hotspot analysis)
git log origin/<default> --since="<window>" --format="" --name-only | grep -v '^$' | sort | uniq -c | sort -rn

# 5. PR numbers from commit messages (extract #NNN patterns)
git log origin/<default> --since="<window>" --format="%s" | grep -oE '#[0-9]+' | sed 's/^#//' | sort -n | uniq | sed 's/^/#/'

# 6. Per-author file hotspots (who touches what)
git log origin/<default> --since="<window>" --format="AUTHOR:%aN" --name-only

# 7. Per-author commit counts (quick summary)
git shortlog origin/<default> --since="<window>" -sn --no-merges

# 8. Greptile triage history (if available)
cat ~/.gstack/greptile-history.md 2>/dev/null || true

# 9. TODOS.md backlog (if available)
cat TODOS.md 2>/dev/null || true

# 10. Test file count
find . -name '*.test.*' -o -name '*.spec.*' -o -name '*_test.*' -o -name '*_spec.*' 2>/dev/null | grep -v node_modules | wc -l

# 11. Regression test commits in window
git log origin/<default> --since="<window>" --oneline --grep="test(qa):" --grep="test(design):" --grep="test: coverage"

# 12. Test files changed in window
git log origin/<default> --since="<window>" --format="" --name-only | grep -E '\.(test|spec)\.' | sort -u | wc -l

Step 2: Compute Metrics

Calculate and present these metrics in a summary table:

Then show a per-author leaderboard immediately below:

Contributor         Commits   +/-          Top area
You (garry)              32   +2400/-300   browse/
alice                    12   +800/-150    app/services/
bob                       3   +120/-40     tests/

Sort by commits descending. The current user (from git config user.name) always appears first, labeled "You (name)".

Greptile signal (if history exists): Read ~/.gstack/greptile-history.md (fetched in Step 1, command 8). Filter entries within the retro time window by date. Count entries by type: fix, fp, already-fixed. Compute signal ratio: (fix + already-fixed) / (fix + already-fixed + fp). If no entries exist in the window or the file doesn't exist, skip the Greptile metric row. Skip unparseable lines silently.

Backlog Health (if TODOS.md exists): Read TODOS.md (fetched in Step 1, command 9). Compute:

• Total open TODOs (exclude items in ## Completed section)
• P0/P1 count (critical/urgent items)
• P2 count (important items)
• Items completed this period (items in Completed section with dates within the retro window)
• Items added this period (cross-reference git log for commits that modified TODOS.md within the window)

Include in the metrics table:

| Backlog Health | N open (X P0/P1, Y P2) · Z completed this period |

If TODOS.md doesn't exist, skip the Backlog Health row.

Skill Usage (if analytics exist): Read ~/.gstack/analytics/skill-usage.jsonl if it exists. Filter entries within the retro time window by ts field. Separate skill activations (no event field) from hook fires (event: "hook_fire"). Aggregate by skill name. Present as:

| Skill Usage | /ship(12) /qa(8) /review(5) · 3 safety hook fires |

If the JSONL file doesn't exist or has no entries in the window, skip the Skill Usage row.

Step 3: Commit Time Distribution

Show hourly histogram in local time using bar chart:

Hour  Commits  ████████████████
 00:    4      ████
 07:    5      █████
 ...

Identify and call out:

• Peak hours
• Dead zones
• Whether pattern is bimodal (morning/evening) or continuous
• Late-night coding clusters (after 10pm)

Step 4: Work Session Detection

Detect sessions using 45-minute gap threshold between consecutive commits. For each session report:

• Start/end time (Pacific)
• Number of commits
• Duration in minutes

Classify sessions:

• Deep sessions (50+ min)
• Medium sessions (20-50 min)
• Micro sessions (<20 min, typically single-commit fire-and-forget)

Calculate:

• Total active coding time (sum of session durations)
• Average session length
• LOC per hour of active time

Step 5: Commit Type Breakdown

Categorize by conventional commit prefix (feat/fix/refactor/test/chore/docs). Show as percentage bar:

feat:     20  (40%)  ████████████████████
fix:      27  (54%)  ███████████████████████████
refactor:  2  ( 4%)  ██

Flag if fix ratio exceeds 50% — this signals a "ship fast, fix fast" pattern that may indicate review gaps.

Step 6: Hotspot Analysis

Show top 10 most-changed files. Flag:

• Files changed 5+ times (churn hotspots)
• Test files vs production files in the hotspot list
• VERSION/CHANGELOG frequency (version discipline indicator)

Step 7: PR Size Distribution

From commit diffs, estimate PR sizes and bucket them:

• Small (<100 LOC)
• Medium (100-500 LOC)
• Large (500-1500 LOC)
• XL (1500+ LOC) — flag these with file counts

Step 8: Focus Score + Ship of the Week

Focus score: Calculate the percentage of commits touching the single most-changed top-level directory (e.g., app/services/, app/views/). Higher score = deeper focused work. Lower score = scattered context-switching. Report as: "Focus score: 62% (app/services/)"

Ship of the week: Auto-identify the single highest-LOC PR in the window. Highlight it:

• PR number and title
• LOC changed
• Why it matters (infer from commit messages and files touched)

Step 9: Team Member Analysis

For each contributor (including the current user), compute:

1. Commits and LOC — total commits, insertions, deletions, net LOC
2. Areas of focus — which directories/files they touched most (top 3)
3. Commit type mix — their personal feat/fix/refactor/test breakdown
4. Session patterns — when they code (their peak hours), session count
5. Test discipline — their personal test LOC ratio
6. Biggest ship — their single highest-impact commit or PR in the window

For the current user ("You"): This section gets the deepest treatment. Include all the detail from the solo retro — session analysis, time patterns, focus score. Frame it in first person: "Your peak hours...", "Your biggest ship..."

For each teammate: Write 2-3 sentences covering what they worked on and their pattern. Then:

• Praise (1-2 specific things): Anchor in actual commits. Not "great work" — say exactly what was good. Examples: "Shipped the entire auth middleware rewrite in 3 focused sessions with 45% test coverage", "Every PR under 200 LOC — disciplined decomposition."
• Opportunity for growth (1 specific thing): Frame as a leveling-up suggestion, not criticism. Anchor in actual data. Examples: "Test ratio was 12% this week — adding test coverage to the payment module before it gets more complex would pay off", "5 fix commits on the same file suggest the original PR could have used a review pass."

If only one contributor (solo repo): Skip the team breakdown and proceed as before — the retro is personal.

If there are Co-Authored-By trailers: Parse Co-Authored-By: lines in commit messages. Credit those authors for the commit alongside the primary author. Note AI co-authors (e.g., noreply@anthropic.com) but do not include them as team members — instead, track "AI-assisted commits" as a separate metric.

Step 10: Week-over-Week Trends (if window >= 14d)

If the time window is 14 days or more, split into weekly buckets and show trends:

• Commits per week (total and per-author)
• LOC per week
• Test ratio per week
• Fix ratio per week
• Session count per week

Step 11: Streak Tracking

Count consecutive days with at least 1 commit to origin/, going back from today. Track both team streak and personal streak:

# Team streak: all unique commit dates (local time) — no hard cutoff
git log origin/<default> --format="%ad" --date=format:"%Y-%m-%d" | sort -u

# Personal streak: only the current user's commits
git log origin/<default> --author="<user_name>" --format="%ad" --date=format:"%Y-%m-%d" | sort -u

Count backward from today — how many consecutive days have at least one commit? This queries the full history so streaks of any length are reported accurately. Display both:

• "Team shipping streak: 47 consecutive days"
• "Your shipping streak: 32 consecutive days"

Step 12: Load History & Compare

Before saving the new snapshot, check for prior retro history:

ls -t .context/retros/*.json 2>/dev/null

If prior retros exist: Load the most recent one using the Read tool. Calculate deltas for key metrics and include a Trends vs Last Retro section:

                    Last        Now         Delta
Test ratio:         22%    →    41%         ↑19pp
Sessions:           10     →    14          ↑4
LOC/hour:           200    →    350         ↑75%
Fix ratio:          54%    →    30%         ↓24pp (improving)
Commits:            32     →    47          ↑47%
Deep sessions:      3      →    5           ↑2

If no prior retros exist: Skip the comparison section and append: "First retro recorded — run again next week to see trends."

Step 13: Save Retro History

After computing all metrics (including streak) and loading any prior history for comparison, save a JSON snapshot:

mkdir -p .context/retros

Determine the next sequence number for today (substitute the actual date for $(date +%Y-%m-%d)):

# Count existing retros for today to get next sequence number
today=$(date +%Y-%m-%d)
existing=$(ls .context/retros/${today}-*.json 2>/dev/null | wc -l | tr -d ' ')
next=$((existing + 1))
# Save as .context/retros/${today}-${next}.json

Use the Write tool to save the JSON file with this schema:

{
  "date": "2026-03-08",
  "window": "7d",
  "metrics": {
    "commits": 47,
    "contributors": 3,
    "prs_merged": 12,
    "insertions": 3200,
    "deletions": 800,
    "net_loc": 2400,
    "test_loc": 1300,
    "test_ratio": 0.41,
    "active_days": 6,
    "sessions": 14,
    "deep_sessions": 5,
    "avg_session_minutes": 42,
    "loc_per_session_hour": 350,
    "feat_pct": 0.40,
    "fix_pct": 0.30,
    "peak_hour": 22,
    "ai_assisted_commits": 32
  },
  "authors": {
    "Garry Tan": { "commits": 32, "insertions": 2400, "deletions": 300, "test_ratio": 0.41, "top_area": "browse/" },
    "Alice": { "commits": 12, "insertions": 800, "deletions": 150, "test_ratio": 0.35, "top_area": "app/services/" }
  },
  "version_range": ["1.16.0.0", "1.16.1.0"],
  "streak_days": 47,
  "tweetable": "Week of Mar 1: 47 commits (3 contributors), 3.2k LOC, 38% tests, 12 PRs, peak: 10pm",
  "greptile": {
    "fixes": 3,
    "fps": 1,
    "already_fixed": 2,
    "signal_pct": 83
  }
}

Note: Only include the greptile field if ~/.gstack/greptile-history.md exists and has entries within the time window. Only include the backlog field if TODOS.md exists. Only include the test_health field if test files were found (command 10 returns > 0). If any has no data, omit the field entirely.

Include test health data in the JSON when test files exist:

  "test_health": {
    "total_test_files": 47,
    "tests_added_this_period": 5,
    "regression_test_commits": 3,
    "test_files_changed": 8
  }

Include backlog data in the JSON when TODOS.md exists:

  "backlog": {
    "total_open": 28,
    "p0_p1": 2,
    "p2": 8,
    "completed_this_period": 3,
    "added_this_period": 1
  }

Step 14: Write the Narrative

Structure the output as:

Tweetable summary (first line, before everything else):

Week of Mar 1: 47 commits (3 contributors), 3.2k LOC, 38% tests, 12 PRs, peak: 10pm | Streak: 47d

Engineering Retro: [date range]

Summary Table

(from Step 2)

Trends vs Last Retro

(from Step 11, loaded before save — skip if first retro)

Time & Session Patterns

(from Steps 3-4)

Narrative interpreting what the team-wide patterns mean:

• When the most productive hours are and what drives them
• Whether sessions are getting longer or shorter over time
• Estimated hours per day of active coding (team aggregate)
• Notable patterns: do team members code at the same time or in shifts?

Shipping Velocity

(from Steps 5-7)

Narrative covering:

• Commit type mix and what it reveals
• PR size discipline (are PRs staying small?)
• Fix-chain detection (sequences of fix commits on the same subsystem)
• Version bump discipline

Code Quality Signals

• Test LOC ratio trend
• Hotspot analysis (are the same files churning?)
• Any XL PRs that should have been split
• Greptile signal ratio and trend (if history exists): "Greptile: X% signal (Y valid catches, Z false positives)"

Test Health

• Total test files: N (from command 10)
• Tests added this period: M (from command 12 — test files changed)
• Regression test commits: list test(qa): and test(design): and test: coverage commits from command 11
• If prior retro exists and has test_health: show delta "Test count: {last} → {now} (+{delta})"
• If test ratio < 20%: flag as growth area — "100% test coverage is the goal. Tests make vibe coding safe."

Focus & Highlights

(from Step 8)

• Focus score with interpretation
• Ship of the week callout

Your Week (personal deep-dive)

(from Step 9, for the current user only)

This is the section the user cares most about. Include:

• Their personal commit count, LOC, test ratio
• Their session patterns and peak hours
• Their focus areas
• Their biggest ship
• What you did well (2-3 specific things anchored in commits)
• Where to level up (1-2 specific, actionable suggestions)

Team Breakdown

(from Step 9, for each teammate — skip if solo repo)

For each teammate (sorted by commits descending), write a section:

[Name]

• What they shipped: 2-3 sentences on their contributions, areas of focus, and commit patterns
• Praise: 1-2 specific things they did well, anchored in actual commits. Be genuine — what would you actually say in a 1:1? Examples:
  • "Cleaned up the entire auth module in 3 small, reviewable PRs — textbook decomposition"
  • "Added integration tests for every new endpoint, not just happy paths"
  • "Fixed the N+1 query that was causing 2s load times on the dashboard"
• Opportunity for growth: 1 specific, constructive suggestion. Frame as investment, not criticism. Examples:
  • "Test coverage on the payment module is at 8% — worth investing in before the next feature lands on top of it"
  • "3 of the 5 PRs were 800+ LOC — breaking these up would catch issues earlier and make review easier"
  • "All commits land between 1-4am — sustainable pace matters for code quality long-term"

AI collaboration note: If many commits have Co-Authored-By AI trailers (e.g., Claude, Copilot), note the AI-assisted commit percentage as a team metric. Frame it neutrally — "N% of commits were AI-assisted" — without judgment.

Top 3 Team Wins

Identify the 3 highest-impact things shipped in the window across the whole team. For each:

• What it was
• Who shipped it
• Why it matters (product/architecture impact)

3 Things to Improve

Specific, actionable, anchored in actual commits. Mix personal and team-level suggestions. Phrase as "to get even better, the team could..."

3 Habits for Next Week

Small, practical, realistic. Each must be something that takes <5 minutes to adopt. At least one should be team-oriented (e.g., "review each other's PRs same-day").

Week-over-Week Trends

(if applicable, from Step 10)

Compare Mode

When the user runs /retro compare (or /retro compare 14d):

1. Compute metrics for the current window (default 7d) using the midnight-aligned start date (same logic as the main retro — e.g., if today is 2026-03-18 and window is 7d, use --since="2026-03-11T00:00:00")
2. Compute metrics for the immediately prior same-length window using both --since and --until with midnight-aligned dates to avoid overlap (e.g., for a 7d window starting 2026-03-11: prior window is --since="2026-03-04T00:00:00" --until="2026-03-11T00:00:00")
3. Show a side-by-side comparison table with deltas and arrows
4. Write a brief narrative highlighting the biggest improvements and regressions
5. Save only the current-window snapshot to .context/retros/ (same as a normal retro run); do not persist the prior-window metrics.

Tone

• Encouraging but candid, no coddling
• Specific and concrete — always anchor in actual commits/code
• Skip generic praise ("great job!") — say exactly what was good and why
• Frame improvements as leveling up, not criticism
• Praise should feel like something you'd actually say in a 1:1 — specific, earned, genuine
• Growth suggestions should feel like investment advice — "this is worth your time because..." not "you failed at..."
• Never compare teammates against each other negatively. Each person's section stands on its own.
• Keep total output around 3000-4500 words (slightly longer to accommodate team sections)
• Use markdown tables and code blocks for data, prose for narrative
• Output directly to the conversation — do NOT write to filesystem (except the .context/retros/ JSON snapshot)

Important Rules

• ALL narrative output goes directly to the user in the conversation. The ONLY file written is the .context/retros/ JSON snapshot.
• Use origin/<default> for all git queries (not local main which may be stale)
• Display all timestamps in the user's local timezone (do not override TZ)
• If the window has zero commits, say so and suggest a different window
• Round LOC/hour to nearest 50
• Treat merge commits as PR boundaries
• Do not read CLAUDE.md or other docs — this skill is self-contained
• On first run (no prior retros), skip comparison sections gracefully