00 hailneed suite · module 03 · closed loop

Failures that repeat,
written down —
then measured.

Name: scar
Author: hailneed

agent-blackbox tells you what went wrong. scar writes it down so it stops: it mines the session logs Claude Code, Codex CLI and Gemini CLI already keep on your disk for failures that recur across separate sessions, drafts the rule, test brief or fix — and later measures whether the lesson held. No network calls, and it never writes into your repo on its own.

Install Source Cloud waitlist

16

Error families
4

Verdicts
3

Agents read
0

Network calls

01 Evidence

This machine's own scars,
ranked by cost.

Abridged from an actual run of --mine --days 90 on the machine this site was built on. Rows that named private projects are left out and long error lines are truncated; the counts are what the miner printed. Nothing in it ever left that machine.

scar mine — markdown out

# scar — recurring failures

Source note: 156 sessions scanned (all, 90d) · 305 failure episodes
             · 6 low-confidence signatures dropped · 16 scars

| Id             | cost | sessions | projects | family            | artifact | error                        |
|----------------|------|----------|----------|-------------------|----------|------------------------------|
| `scar-0eqc684` |   68 |       14 |        5 | shell-quoting     | rule     | unexpected EOF while looki…  |
| `scar-0qkezmw` |   42 |        8 |        4 | edit-precondition | rule     | <tool_use_error>String to…  |
| `scar-12srzqa` |   36 |        6 |        5 | not-a-git-repo    | rule     | fatal: not a git repositor…  |
| `scar-08kw0mp` |   12 |        2 |        2 | timeout           | rule     | Command timed out after 2m…  |
| `scar-0w2b7dp` |   12 |        2 |        2 | compile-error     | test     | Build failed. Use dotnet b…  |

## What to do

`node scar.mjs --draft scar-0eqc684` → rule

The ranking is by cost, not raw count — separate sessions × 3, projects touched × 2, repeats capped, +4 when more than one agent hit the same wall. One bad afternoon of retries counts as a single episode. The 16 families that classify each scar are a pattern list you can open, and the next step is printed under the table.

02 Install

One marketplace.
Then one command.

claude code

# once
> /plugin marketplace add hailneed/plugins

# the closed loop
> /plugin install scar@hailneed

# and try it
> /scar:mine

Claude Code and Node.js 18 or newer.
No dependencies, no API key, no quota spent.
Standalone works too — node scripts/scar.mjs --mine --md --lang en
CI-ready — --verify --out verify.json has a stable output format; gate on written[].verdict.

Marketplace manifest

03 Commands

Three commands.
One closed loop.

`/scar:mine`

Recurring failures, ranked by what they cost: which error came back in how many separate sessions and projects, the commands that failed, and what worked right after. When most episodes end with a different tool succeeding, the report says so — the lesson is a tool choice, not a better command.

`/scar:write <id>`

The durable lesson: a rule, a regression-test brief, an environment fix or a decision record — each carrying an evidence line and a scar marker so the result can be measured later. It shows you the draft and asks; it never writes into your repo on its own.

`/scar:verify`

Did the lesson hold? For every marked artifact, the failure's recurrence count before and after it was written. Four verdicts: held, recurred, too recent, no evidence. A rule that recurred is a finding about the rule.

04 Trust

Claims you can
check in the source.

No network calls, no repo writes. Drafts go to stdout — scar.mjs contains no fetch, no sockets, and you decide what lands in the repo.
16 families, no model judgement — scars.mjs is a pattern list you can read, and --selftest proves it without touching your data.
Retry loops do not inflate the ranking. An episode is one run of consecutive failures plus the first success after — twenty attempts in one session is one lesson.
The loop only closes with evidence. verify counts recurrences before and after the marker's date; without a marker, whether a rule works stays a matter of opinion.
Failure stays visible. Unreadable sessions and dropped low-confidence signatures are counted in the source note, never silently hidden.
MIT. LICENSE — no account, no signup, no telemetry.

05 Cloud

scar Cloud
is in design.

The plugin stays free and local — that is a promise, not a phase. Cloud is the optional layer for teams that hit the same walls separately:

Team-wide scar pool — the wall one person hit becomes everyone's rule.
Rule-effectiveness time series — which lessons hold across the team, and which quietly stopped working.
Onboarding summary — "known traps in this repo", ready for whoever joins next.