feat: lifetime stats that count every session — and grunt like caveman (pile view for --all) #716

Problem

The lifetime number has two problems: it is incomplete, and what it shows talks like an accountant.

History has one writer: main() in src/hooks/caveman-stats.js (append at :495-506), and it runs only when the user types /caveman-stats (skills/caveman-stats/SKILL.md: "Triggers on /caveman-stats"). Forget the command → session never counted. --all, --since 7d, and the ⛏ statusline badge undercount forever. Verified on main @ 0d95a81.

Before: 10 caveman sessions, /caveman-stats typed in 2

Caveman Stats — Lifetime
──────────────────────────
Sessions:   2                  ← 8 sessions gone. pile has hole.
Output tokens:         81,340
Est. tokens saved:     151,060
Est. saved (USD):      ~$2.27

Request

1. SessionEnd hook auto-records a snapshot. New --record flag on caveman-stats.js: same parse → attribute → append path, no stdout. Safe by design — aggregateHistory keeps only the latest row per session_id (:492-494), so extra appends fold away. Verified end-to-end on Claude Code v2.1.212: SessionEnd delivers {session_id, transcript_path, reason} on stdin, and the unmodified script already appends the correct row from transcript_path (622 output tokens / 2 turns; est_saved_tokens: 0 with caveman off — no savings invented). A hard-killed session gets no SessionEnd; the dedup above means a per-turn upgrade can close that gap later.

2. --all grunts like caveman. Same numbers, same honesty rules (est. labels, output-only, never call it "usage" — per the outputReductionPct comment), caveman voice:

After:

🪨 caveman pile
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
sessions       10
mouth say      412,680 token
mouth not say  766,406 token  ⛏
pile meter     █████████████░░░░░░░  65% of would-be output (est.)
~$11.50 stay in cave

numbers est. — output only. input not touched.
why use many token when few do trick

Two PRs if preferred — record first, grunt second. One concern per PR.

Why good

Number only honest if complete. The repo already treats invented savings as a bug (#601, docs/HONEST-NUMBERS.md) — undercounting is the same sickness in the other direction. #703's rolling statusline window only means something over dense history. And the pile view makes the user smile on every --all. Small mouth, big pile.

Related

• Optional rolling-window savings suffix for the statusline #703 — rolling statusline window (needs dense history)
• caveman-stats: whole-session tokens attributed to the mode active at stats time — savings inflated or zeroed on mid-session mode change #601 — per-mode attribution (reused unchanged)
• PR docs: add Companion tools section (savings-mirror + sovacount) #458 — savings-mirror external dashboard (complementary, out-of-tree)

Happy to PR the SessionEnd --record first if that's the preferred direction.