/retro — the trend across sessions

/journal records one session; /retro reads many and says where the line is heading. Not a summary — a trend, with the numbers that make "we're slipping" or "the eval is climbing" a fact instead of a feeling.

Adjacent skills: /journal (one session's worklog; /retro trends across many) · /audit eval (one report's honesty; /retro the trend across runs) · /triage (grooms the backlog; /retro reviews the trajectory).

Run before the skill's steps — per invocation, not per session (4.36); failures degrade to markdown:

link="$(readlink "$HOME/.claude/skills/health" 2>/dev/null || true)"   # empty = not symlinked
pack="$(dirname "$(dirname "$link")")"   # NEVER trust this unless $link was non-empty
if [ "${link#/}" != "$link" ] && [ -x "$pack/bin/acstack-config" ] && ! "$pack/bin/acstack-config" runtime | grep -q '=off'; then
  "$pack/bin/acstack-config" || true          # resolved keys, with sources
  "$pack/bin/acstack-update-check" || true    # ≤1 fetch/day; silent ONLY if already checked today
  "$pack/bin/acstack-recall" || true          # LEARNINGS.md + bug-class names, capped 3KB
else
  echo "runtime off — proceeding without recall/update-check"
fi

Operating principles

• Be direct. Push back in writing when the plan or the user is wrong. No sycophancy.
• Never delete a decision. Supersede it: ~~old~~ → **Verdict (YYYY-MM-DD):** new call — reason.
• Never fix, tune, or delete a test or eval case to raise a score. Log the miss honestly and leave the case unchanged.
• Name exact things: regex patterns, function signatures, model names, before → after numbers. Never "fixed bugs".
• Attribution: follow the project's attribution setting (default none) — no AI-tool mentions in generated docs, no attribution trailers in commits or PRs. Commit with explicit -m/-F messages only.
• Config: read .claude/acstack.md at the project root (fall back to ~/.claude/acstack.md) before acting. ## Settings keys override pack defaults; a ## <skill-name> section overrides both. Unknown keys and sections are ignored.
• Docs: BRIEF.md (frozen seed) / PLAN.md (living plan) / JOURNAL.md (rolling journal). If the repo uses legacy names (PLANNING_PROMPT.md / PLANNING.md / STATUS.md), use those instead — never create both.
• Recall: if LEARNINGS.md exists at the project root, read it before starting.
• Conduct: follow the acstack-conduct block in this repo's AGENTS.md — the word is the mode; the user sets the pace.
• Hackathon lane: if the project's AGENTS.md carries the acstack:hackathon-lane block, only /do changes the repository during the event. Any other skill that would write a tracked file, commit or push says what it would have done and stops; a change that is not a task goes through the lane's operator route.

One document set. Resolve exactly ONE BRIEF/PLAN/JOURNAL set and name its path in the report's scope line. If more than one candidate set exists — a monorepo, nested products, an apps/* tree each with its own docs — list the candidates and STOP. Never pick one silently: a confident answer about the wrong product is worse than no answer (conduct rule 8).

Inputs

• JOURNAL.md entries since the last retro (the window; week or phase N in the argument narrows it).
• PLAN.md: planned phase dates, exit criteria, the open risks and items.
• Eval artifacts when present: eval/spec.md targets and the result files across runs.
• git log over the window for commit / checkbox velocity.

Retrieve by window, don't ingest the file. Past roughly 500 lines, JOURNAL.md is read headings-first: scan the ### entry headings and their dates, select the ones inside the window (week, phase N, or since the last retro), and fetch full text for those only. Entries outside the window are not evidence for this retro — reading them wastes budget and, worse, invites a trend claim drawn from data the window explicitly excluded. State the window and how many entries fell inside it, so a reader can tell a five-entry trend from a one-entry anecdote.

Missing inputs are named, never worked around. No JOURNAL.md → stop: a retro is a trend across recorded sessions, and without the record there is no trend, only the git log's shape — say that and point at /journal. No PLAN.md → run the trends that only need the journal and state that velocity-vs-plan and the risk review were skipped for want of the plan. A window containing one entry is reported as one entry, not extrapolated into a trend.

Sections

The four sections live in references/retro-sections.md with their question sets and honest-degradation lines. Lead with a verdict: on plan / slipping — <where> / off plan.

1. Velocity vs plan. Planned phase dates vs actual; boxes or issues closed per period vs the plan's implied rate; slippage named in days with the cause pulled from journal entries, not guessed.
2. Eval trend. Headline score per run across the window, per-category direction, distance to target. No eval history → one honest line and the section ends.
3. Failure-category trends. Counts by class from the journal's eval triage sections and /investigate write-ups; a class recurring 2+ times is named as a /learn promotion candidate.
4. Risk review. Each open PLAN risk: still real / materialized / retired, with evidence. New risks are proposed as dated PLAN edits — proposed, never applied by /retro.

Not in wave 3

No skill-usage / telemetry section — it arrives with the local telemetry it reads (PLAN task 4.3, moved to wave 4.5 post-launch by the 2026-07-29 split). Don't emit a placeholder for it; its absence is correct, not a gap.

Output

Append to JOURNAL.md as a dated entry under ## Key decisions and journey, newest first: ### Retro (YYYY-MM-DD — <window>). This is the same anchor /journal writes at, so a retro and a journal entry from two concurrent sessions conflict — which is the safe outcome, and is resolved by keeping both entries rather than choosing one (see /journal step 2). A journal without that heading — hand-kept rather than seeded from /journal's template — takes the entry per that journal's own convention: appended where its entries actually go (top of a newest-first record, bottom of a chronological one), with the divergence named inside the entry; never scaffold the pack's skeleton into a journal the project keeps by hand, and never impose the pack's ordering on it. Commit using the project's journal-commit-format (pack default Journal <date>: <summary>) with retro — <summary> as the summary, brief body, attribution per config. PLAN edits the retro proposes are listed for the user to apply via /plan replan — /retro writes the journal, not the plan.

Tickets-mode delta

Velocity becomes closed issues + milestone burn via gh issue list --state closed and the milestone API; failure classes are additionally mined from issue labels and closing comments. Preconditions — gh installed, gh auth status succeeding, and a GitHub remote present. Any failure names WHICH one failed and offers document mode; never guess.