Tandem vendoring note. Vendored from gstack (MIT, (c) Garry Tan, https://github.com/garrytan/gstack @ a3259400). The upstream Claude-Code-specific boilerplate (telemetry, session tracking, update checks, plan-mode hooks, learnings/brain sync) was removed; the workflow itself is unchanged. Paths below are relative to this skill's directory; sibling skills live at ../<id>/ (ids are prefixed gstack-). $GSTACK_ROOT is an optional upstream gstack install (default ~/.claude/skills/gstack) needed only for optional helpers such as the browse binary; skip any step that needs it when it is absent. "Ask the user" means a plain chat question when no structured question tool exists.

When to invoke this skill

Analyzes commit history, work patterns, and code quality metrics with persistent history and trend tracking. Team-aware: breaks down per-person contributions with praise and growth areas. Use when asked to "weekly retro", "what did we ship", or "engineering retrospective". Proactively suggest at the end of a work week or sprint.

Step 0: Detect platform and base branch

First, detect the git hosting platform from the remote URL:

git remote get-url origin 2>/dev/null

• If the URL contains "github.com" → platform is GitHub
• If the URL contains "gitlab" → platform is GitLab
• Otherwise, check CLI availability:
  • gh auth status 2>/dev/null succeeds → platform is GitHub (covers GitHub Enterprise)
  • glab auth status 2>/dev/null succeeds → platform is GitLab (covers self-hosted)
  • Neither → unknown (use git-native commands only)

Determine which branch this PR/MR targets, or the repo's default branch if no PR/MR exists. Use the result as "the base branch" in all subsequent steps.

If GitHub:

1. gh pr view --json baseRefName -q .baseRefName — if succeeds, use it
2. gh repo view --json defaultBranchRef -q .defaultBranchRef.name — if succeeds, use it

If GitLab:

1. glab mr view -F json 2>/dev/null and extract the target_branch field — if succeeds, use it
2. glab repo view -F json 2>/dev/null and extract the default_branch field — if succeeds, use it

Git-native fallback (if unknown platform, or CLI commands fail):

1. git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null | sed 's|refs/remotes/origin/||'
2. If that fails: git rev-parse --verify origin/main 2>/dev/null → use main
3. If that fails: git rev-parse --verify origin/master 2>/dev/null → use master

If all fail, fall back to main.

Print the detected base branch name. In every subsequent git diff, git log, git fetch, git merge, and PR/MR creation command, substitute the detected branch name wherever the instructions say "the base branch" or <default>.

/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
• /retro global — cross-project retro across all AI coding tools (7d default)
• /retro global 14d — cross-project retro 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 (optionally followed by a window), or the word global (optionally followed by a window), show this usage and stop:

Usage: /retro [window | compare | global]
  /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
  /retro global       — cross-project retro across all AI tools (7d default)
  /retro global 14d   — cross-project retro with explicit window

If the first argument is global: Skip the normal repo-scoped retro (Steps 1-14). Instead, follow the Global Retrospective flow at the end of this document. The optional second argument is the time window (default 7d). This mode does NOT require being inside a git repo.

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 distribution and what it reveals about shipping cadence
• 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?)
• 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."

Plan Completion

Check review JSONL logs for plan completion data from /ship runs this period:

setopt +o nomatch 2>/dev/null || true  # zsh compat
eval "$($GSTACK_ROOT/bin/gstack-slug 2>/dev/null)"
cat ~/.gstack/projects/$SLUG/*-reviews.jsonl 2>/dev/null | grep '"skill":"ship"' | grep '"plan_items_total"' || echo "NO_PLAN_DATA"

If plan completion data exists within the retro time window:

• Count branches shipped with plans (entries that have plan_items_total > 0)
• Compute average completion: sum of plan_items_done / sum of plan_items_total
• Identify most-skipped item category if data supports it

Output:

Plan Completion This Period:
  {N} branches shipped with plans
  Average completion: {X}% ({done}/{total} items)

If no plan data exists, skip this section silently.

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"
  • "Most commits land in a single burst — spacing work across the day could reduce context-switching fatigue"
  • "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)

Global Retrospective Mode

When the user runs /retro global (or /retro global 14d), follow this flow instead of the repo-scoped Steps 1-14. This mode works from any directory — it does NOT require being inside a git repo.

Global Step 1: Compute time window

Same midnight-aligned logic as the regular retro. Default 7d. The second argument after global is the window (e.g., 14d, 30d, 24h).

Global Step 2: Run discovery

Locate and run the discovery script using this fallback chain:

DISCOVER_BIN=""
[ -x $GSTACK_ROOT/bin/gstack-global-discover ] && DISCOVER_BIN=$GSTACK_ROOT/bin/gstack-global-discover
[ -z "$DISCOVER_BIN" ] && [ -x $GSTACK_ROOT/bin/gstack-global-discover ] && DISCOVER_BIN=$GSTACK_ROOT/bin/gstack-global-discover
[ -z "$DISCOVER_BIN" ] && which gstack-global-discover >/dev/null 2>&1 && DISCOVER_BIN=$(which gstack-global-discover)
[ -z "$DISCOVER_BIN" ] && [ -f bin/gstack-global-discover.ts ] && DISCOVER_BIN="bun run bin/gstack-global-discover.ts"
echo "DISCOVER_BIN: $DISCOVER_BIN"

If no binary is found, tell the user: "Discovery script not found. Run bun run build in the gstack directory to compile it." and stop.

Run the discovery:

$DISCOVER_BIN --since "<window>" --format json 2>/tmp/gstack-discover-stderr

Read the stderr output from /tmp/gstack-discover-stderr for diagnostic info. Parse the JSON output from stdout.

If total_sessions is 0, say: "No AI coding sessions found in the last <window>. Try a longer window: /retro global 30d" and stop.

Global Step 3: Run git log on each discovered repo

For each repo in the discovery JSON's repos array, find the first valid path in paths[] (directory exists with .git/). If no valid path exists, skip the repo and note it.

For local-only repos (where remote starts with local:): skip git fetch and use the local default branch. Use git log HEAD instead of git log origin/$DEFAULT.

For repos with remotes:

git -C <path> fetch origin --quiet 2>/dev/null

Detect the default branch for each repo: first try git symbolic-ref refs/remotes/origin/HEAD, then check common branch names (main, master), then fall back to git rev-parse --abbrev-ref HEAD. Use the detected branch as <default> in the commands below.

# Commits with stats
git -C <path> log origin/$DEFAULT --since="<start_date>T00:00:00" --format="%H|%aN|%ai|%s" --shortstat

# Commit timestamps for session detection, streak, and context switching
git -C <path> log origin/$DEFAULT --since="<start_date>T00:00:00" --format="%at|%aN|%ai|%s" | sort -n

# Per-author commit counts
git -C <path> shortlog origin/$DEFAULT --since="<start_date>T00:00:00" -sn --no-merges

# PR/MR numbers from commit messages (GitHub #NNN, GitLab !NNN)
git -C <path> log origin/$DEFAULT --since="<start_date>T00:00:00" --format="%s" | grep -oE '[#!][0-9]+' | sort -t'#' -k1 | uniq

For repos that fail (deleted paths, network errors): skip and note "N repos could not be reached."

Global Step 4: Compute global shipping streak

For each repo, get commit dates (capped at 365 days):

git -C <path> log origin/$DEFAULT --since="365 days ago" --format="%ad" --date=format:"%Y-%m-%d" | sort -u

Union all dates across all repos. Count backward from today — how many consecutive days have at least one commit to ANY repo? If the streak hits 365 days, display as "365+ days".

Global Step 5: Compute context switching metric

From the commit timestamps gathered in Step 3, group by date. For each date, count how many distinct repos had commits that day. Report:

• Average repos/day
• Maximum repos/day
• Which days were focused (1 repo) vs. fragmented (3+ repos)

Global Step 6: Per-tool productivity patterns

From the discovery JSON, analyze tool usage patterns:

• Which AI tool is used for which repos (exclusive vs. shared)
• Session count per tool
• Behavioral patterns (e.g., "Codex used exclusively for myapp, Claude Code for everything else")

Global Step 7: Aggregate and generate narrative

Structure the output with the shareable personal card first, then the full team/project breakdown below. The personal card is designed to be screenshot-friendly — everything someone would want to share on X/Twitter in one clean block.

Tweetable summary (first line, before everything else):

Week of Mar 14: 5 projects, 138 commits, 250k LOC across 5 repos | 48 AI sessions | Streak: 52d 🔥

🚀 Your Week: [user name] — [date range]

This section is the shareable personal card. It contains ONLY the current user's stats — no team data, no project breakdowns. Designed to screenshot and post.

Use the user identity from git config user.name to filter all per-repo git data. Aggregate across all repos to compute personal totals.

Render as a single visually clean block. Left border only — no right border (LLMs can't align right borders reliably). Pad repo names to the longest name so columns align cleanly. Never truncate project names.

╔═══════════════════════════════════════════════════════════════
║  [USER NAME] — Week of [date]
╠═══════════════════════════════════════════════════════════════
║
║  [N] commits across [M] projects
║  +[X]k LOC added · [Y]k LOC deleted · [Z]k net
║  [N] AI coding sessions (CC: X, Codex: Y, Gemini: Z)
║  [N]-day shipping streak 🔥
║
║  PROJECTS
║  ─────────────────────────────────────────────────────────
║  [repo_name_full]        [N] commits    +[X]k LOC    [solo/team]
║  [repo_name_full]        [N] commits    +[X]k LOC    [solo/team]
║  [repo_name_full]        [N] commits    +[X]k LOC    [solo/team]
║
║  SHIP OF THE WEEK
║  [PR title] — [LOC] lines across [N] files
║
║  TOP WORK
║  • [1-line description of biggest theme]
║  • [1-line description of second theme]
║  • [1-line description of third theme]
║
║  Powered by gstack
╚═══════════════════════════════════════════════════════════════

Rules for the personal card:

• Only show repos where the user has commits. Skip repos with 0 commits.
• Sort repos by user's commit count descending.
• Never truncate repo names. Use the full repo name (e.g., analyze_transcripts not analyze_trans). Pad the name column to the longest repo name so all columns align. If names are long, widen the box — the box width adapts to content.
• For LOC, use "k" formatting for thousands (e.g., "+64.0k" not "+64010").
• Role: "solo" if user is the only contributor, "team" if others contributed.
• Ship of the Week: the user's single highest-LOC PR across ALL repos.
• Top Work: 3 bullet points summarizing the user's major themes, inferred from commit messages. Not individual commits — synthesize into themes. E.g., "Built /retro global — cross-project retrospective with AI session discovery" not "feat: gstack-global-discover" + "feat: /retro global template".
• The card must be self-contained. Someone seeing ONLY this block should understand the user's week without any surrounding context.
• Do NOT include team members, project totals, or context switching data here.

Personal streak: Use the user's own commits across all repos (filtered by --author) to compute a personal streak, separate from the team streak.

Global Engineering Retro: [date range]

Everything below is the full analysis — team data, project breakdowns, patterns. This is the "deep dive" that follows the shareable card.

All Projects Overview

Per-Project Breakdown

For each repo (sorted by commits descending):

• Repo name (with % of total commits)
• Commits, LOC, PRs merged, top contributor
• Key work (inferred from commit messages)
• AI sessions by tool

Your Contributions (sub-section within each project): For each project, add a "Your contributions" block showing the current user's personal stats within that repo. Use the user identity from git config user.name to filter. Include:

• Your commits / total commits (with %)
• Your LOC (+insertions / -deletions)
• Your key work (inferred from YOUR commit messages only)
• Your commit type mix (feat/fix/refactor/chore/docs breakdown)
• Your biggest ship in this repo (highest-LOC commit or PR)

If the user is the only contributor, say "Solo project — all commits are yours." If the user has 0 commits in a repo (team project they didn't touch this period), say "No commits this period — [N] AI sessions only." and skip the breakdown.

Format:

**Your contributions:** 47/244 commits (19%), +4.2k/-0.3k LOC
  Key work: Writer Chat, email blocking, security hardening
  Biggest ship: PR #605 — Writer Chat eats the admin bar (2,457 ins, 46 files)
  Mix: feat(3) fix(2) chore(1)

Cross-Project Patterns

• Time allocation across projects (% breakdown, use YOUR commits not total)
• Peak productivity hours aggregated across all repos
• Focused vs. fragmented days
• Context switching trends

Tool Usage Analysis

Per-tool breakdown with behavioral patterns:

• Claude Code: N sessions across M repos — patterns observed
• Codex: N sessions across M repos — patterns observed
• Gemini: N sessions across M repos — patterns observed

Ship of the Week (Global)

Highest-impact PR across ALL projects. Identify by LOC and commit messages.

3 Cross-Project Insights

What the global view reveals that no single-repo retro could show.

3 Habits for Next Week

Considering the full cross-project picture.

Global Step 8: Load history & compare

setopt +o nomatch 2>/dev/null || true  # zsh compat
ls -t ~/.gstack/retros/global-*.json 2>/dev/null | head -5

Only compare against a prior retro with the same window value (e.g., 7d vs 7d). If the most recent prior retro has a different window, skip comparison and note: "Prior global retro used a different window — skipping comparison."

If a matching prior retro exists, load it with the Read tool. Show a Trends vs Last Global Retro table with deltas for key metrics: total commits, LOC, sessions, streak, context switches/day.

If no prior global retros exist, append: "First global retro recorded — run again next week to see trends."

Global Step 9: Save snapshot

mkdir -p ~/.gstack/retros

Determine the next sequence number for today:

setopt +o nomatch 2>/dev/null || true  # zsh compat
today=$(date +%Y-%m-%d)
existing=$(ls ~/.gstack/retros/global-${today}-*.json 2>/dev/null | wc -l | tr -d ' ')
next=$((existing + 1))

Use the Write tool to save JSON to ~/.gstack/retros/global-${today}-${next}.json:

{
  "type": "global",
  "date": "2026-03-21",
  "window": "7d",
  "projects": [
    {
      "name": "gstack",
      "remote": "<detected from git remote get-url origin, normalized to HTTPS>",
      "commits": 47,
      "insertions": 3200,
      "deletions": 800,
      "sessions": { "claude_code": 15, "codex": 3, "gemini": 0 }
    }
  ],
  "totals": {
    "commits": 182,
    "insertions": 15300,
    "deletions": 4200,
    "projects": 5,
    "active_days": 6,
    "sessions": { "claude_code": 48, "codex": 8, "gemini": 3 },
    "global_streak_days": 52,
    "avg_context_switches_per_day": 2.1
  },
  "tweetable": "Week of Mar 14: 5 projects, 182 commits, 15.3k LOC | CC: 48, Codex: 8, Gemini: 3 | Focus: gstack (58%) | Streak: 52d"
}

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
• Global mode: Does NOT require being inside a git repo. Saves snapshots to ~/.gstack/retros/ (not .context/retros/). Gracefully skip AI tools that aren't installed. Only compare against prior global retros with the same window value. If streak hits 365d cap, display as "365+ days".