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Zestaw pętli retro: zamień nieudaną sesję Claude Code w kontrolę

9 min czytania

TL;DR i werdykt

Gdy Claude Code ignoruje regułę, odruchem jest głośniejsza linia w CLAUDE.md. Docsy mówią, dlaczego to nie działa: Claude traktuje te pliki jako kontekst, nie wymuszoną konfigurację, a żeby zablokować akcję, używa się hooka. s4 Pętla retro idzie w drugą stronę: mniej linii i kontrola, której nie da się zignorować.

W naszym biegu jedna sesja Claude Code zbudowała funkcję not kredytowych na małym API do faktur i wypuściła buga w numeracji przy zielonych własnych testach. Retro tej sesji, któremu powiedziano, co poszło nie tak, zaproponowało, co by temu zapobiegło. Zatwierdziliśmy ręcznie cztery zmiany: hook pre-commit, test, jedną linię standardów i jeden komentarz przy źródle. Świeża sesja z tym samym żądaniem wypuściła potem numery bez dziur.

Werdykt:

  • Puść retro po sesji, która poszła źle, zanim ją wyczyścisz, albo na logu starej sesji.
  • Nie puszczaj go na autopilocie. Tylko proponuje, a nic się nie zmienia, dopóki nie wybierzesz kandydata. s2
  • Prześledź każdego kandydata do momentu transkryptu i odrzuć tych, których nie umiesz prześledzić.
  • Skieruj każdego ocalałego do właściwego nośnika: kontrola dla błędu mechanicznego, linia standardów dla decyzji opartej na osądzie, komentarz przy źródle dla luki w nawigacji.
  • Kontrole, które dodajesz, to kod, który teraz utrzymujesz. Retro nie audytuje kontroli, które zaproponowało w zeszłym miesiącu. s2

Paczka poniżej zawiera checklistę, skrypt hooka i test numeracji z naszego biegu.

Synteza ze źródłami

Czym jest retro. To skill z kolekcji Matta Pococka. Uruchamia się go tylko ręcznie (disable-model-invocation: true) i szuka kandydatów w siedmiu kategoriach: Navigation, Automated checks, Coding standards, Global AGENTS.md, Tool economy, No-ops i Information access. s1 Jego ostatni krok tylko przedstawia kandydatów, według wagi. s1 Trafił do pluginu Claude Code w wersji v1.3.0. s22

Jak go zainstalować. Linia instalacji to claude plugin install mattpocock-skills@claude-plugins-official. s25 Jedna pułapka: issue zgłaszało brak komendy retro przy instalacji z oficjalnego marketplace. s24 Wpis w marketplace przypina teraz nowszy commit. s26 Na naszej maszynie lokalny marketplace nadal miał stare przypięcie, więc najpierw puściliśmy aktualizację marketplace, potem instalację, a potem sprawdziliśmy komendę w nowej sesji.

Dlaczego log, a nie kod. Claude Code zapisuje transkrypty jako JSONL w ~/.claude/projects/<project>/<session-id>.jsonl, a claude --resume <transcript-path> wznawia sesję z tego pliku. s8 Format jest wewnętrzny i zmienia się między wersjami, więc nie buduj na nim skryptów. s8 Retencja wynosi 30 dni i da się ją skonfigurować przez cleanupPeriodDays. s8

Retro jest hałaśliwe, dopóki go nie prześledzisz. Docsy każą odrzucać każdego kandydata, którego nie umiesz powiązać z konkretnym momentem. s2 Ostrzegają też, że model zapomina o zmaganiach ze środka sesji i wymyśla ogólne rady, żeby zaspokoić kategorie. s2 Otwarte issue zlicza 17 uruchomień retro w 12 sesjach, z czego po 15 użytkownik prosił agenta o dowód, że kandydaci byli potrzebni, i domaga się, żeby zero ocalałych liczyło się jako kompletne retro. s7

Skieruj każdego ocalałego. Repo bez zabezpieczenia, czyli bez hooka pre-commit i bez zadania CI uruchamiającego komendę lint, typecheck lub test, samo jest ustaleniem. s1 Naruszenie mechaniczne dostaje deterministyczną kontrolę, kropka. s1 Pliki sterujące należy używać niesłychanie rzadko, zwykle tylko na wskaźniki nawigacyjne do innych plików. s1 Programista, który prowadzi pętlę lekcji na produkcji, dochodzi do tej samej drabiny: reguła, która się osuwa, staje się testem, regułą lintera albo hookiem. s6

Trzymaj CLAUDE.md małym. Docsy celują w mniej niż 200 linii na plik CLAUDE.md, bo dłuższe pliki zużywają więcej kontekstu i obniżają przestrzeganie reguł. s4 Ich test dla każdej linii: czy usunięcie jej sprawiłoby, że Claude zacznie popełniać błędy? Jeśli nie, wytnij. s9 Tryb porażki zwany rozdęciem, czyli zignorowana reguła, która dostaje głośniejszą regułę i dłuższy plik, opisuje jeden programista. s10

Domknij pętlę. Docsy każą traktować CLAUDE.md jak kod: przeglądać go, gdy coś idzie źle, regularnie przycinać i testować zmiany, obserwując, czy zachowanie Claude naprawdę się zmienia. s9 /doctor prompt-audit wymaga Claude Code v2.1.283 lub nowszego, zgłasza ustalenia z proponowanymi zmianami i niczego nie zmienia, dopóki o to nie poprosisz. s4 Działa przez wbudowany skill claude-api, więc jest niedostępny, gdy ten skill jest wyłączony. s4 A otwarte issue opisuje retro, które wdraża zatwierdzone zmiany, a potem zapomina o commicie. s23

Co zobaczyliśmy w naszym biegu. Pierwsze retro zaczęło się od "This session was smooth", bo sesja nigdy nie dowiedziała się, że zawiodła. Dopiero gdy zgłosiliśmy porażkę jako argument, znalazło przyczynę, numer wzięty przed walidacją. Szczegóły w pomiarach poniżej.

Kod

Każdy plik jest prawdziwy z naszego biegu albo jest skryptem, którego użyliśmy do jego przeprowadzenia. Dostosuj ścieżki do swojego repo.

retro-checklist.md to checklista ze strony jako plik: siedem gestów, pytanie śledzące słowo w słowo, cztery nośniki, przypomnienie o commicie i pułapka ścieżki w prompt-audit.

retro-checklist.md

# The retro checklist

Run it after a session that went wrong, before you clear it, or later on the old session's log.

## The seven gestures

1. Install: `claude plugin marketplace update claude-plugins-official`, then `claude plugin install mattpocock-skills@claude-plugins-official --scope project`. Open a NEW session, type a slash, check that the retro command is listed.
2. Run your real task in a plain session. Let it finish. Keep the session open.
3. Run the retro in that session, then run it again with what failed written after it, as its argument. The retro reads the session log, and a session that never learned it failed will call itself smooth.
4. Trace every candidate. Type this, word for word:

   > For each candidate, quote the moment of this session's transcript that backs it; drop any candidate you cannot trace to a specific moment.

   Zero survivors is a valid retro. Weaker survivors are a judgement call: you decide.
5. Approve one survivor at a time, each into its carrier (below). One change per turn, read the diff after each.
6. Run the prompt audit WITH a path, apply its edits if any, then commit the files yourself. The retro proposes and edits, it does not commit.
7. Re-run the same task in a fresh session and watch what it reads first and whether the failure happens again.

## The four carriers

| What failed | Carrier | Example from our run |
| --- | --- | --- |
| A mechanical failure | A deterministic check: a pre-commit hook, a test, a lint rule, a CI job | `pre-commit.sh` (typecheck, then tests) and `numbering.test.ts` |
| A judgement call | One line in `CODING_STANDARDS.md`, read by the reviewer | `CODING_STANDARDS.md` |
| A navigation gap | A comment at the source, or one CLAUDE.md pointer if a comment cannot do it | A doc comment above `nextId` |
| Nothing the above can hold | Do not write a rule | Both retros declined a CLAUDE.md line |

## Traps

- Commit reminder: the retro can implement what you approve and then leave the files uncommitted. Stage the approved files and commit them yourself.
- A new hook checks the working tree, not the commit. If the tree still holds the bug, the hook refuses the commit. Fix the code first, then commit.
- A cherry-pick does not run the pre-commit hook.
- Prompt-audit path trap: `/doctor prompt-audit` with no path audited the user-level files under `~/.claude`, not the repo, and said nothing about the new files. Give it the path: `/doctor prompt-audit CODING_STANDARDS.md`.
- The retro has no dry-run mode. Try a proposed check against the repo before you let it block merges.
- Do not wire the retro to a session-end hook. Keep a human on the approval.
- Keep the transcript format out of your scripts: it is internal and changes between versions.

retro-checklist.md on GitHub

pre-commit.sh to hook, który zatwierdziliśmy. Puszcza typecheck, potem testy i blokuje commit, jeśli któreś padnie. Zapisz go jako .githooks/pre-commit, nadaj mu prawo wykonywania i uruchom git config core.hooksPath .githooks.

pre-commit.sh

#!/bin/sh
set -e
pnpm typecheck
pnpm test

pre-commit.sh on GitHub

numbering.test.ts to test vitest, który zatwierdziliśmy. Blokuje jedną regułę: odrzucone żądanie noty kredytowej nie spala żadnego numeru.

numbering.test.ts

import { describe, expect, it } from "vitest";
import { seedCustomer, seedOpenInvoice, testApp } from "./helpers";

describe("credit note numbering", () => {
  it("does not burn a number on a rejected request", async () => {
    const app = testApp();
    const customerId = await seedCustomer(app);
    const id = await seedOpenInvoice(app, { customerId, unitPrice: 10_000 });
    await app.handle("POST", `/invoices/${id}/pay`);
    const url = `/invoices/${id}/credit-notes`;

    const first = await app.handle("POST", url, { amount: 4_000 });
    expect(first.body).toMatchObject({ number: "CN-0001" });

    const rejected = await app.handle("POST", url, { amount: 6_001 });
    expect(rejected.status).not.toBe(201);

    const next = await app.handle("POST", url, { amount: 6_000 });
    expect(next.status).toBe(201);
    expect(next.body).toMatchObject({ number: "CN-0002" });
  });
});

numbering.test.ts on GitHub

CODING_STANDARDS.md to jedna linia standardów, którą zatwierdziliśmy, plik czytany przez recenzenta.

CODING_STANDARDS.md

# Coding standards

- Take a sequence number (`nextId`) only once every validation has passed, so a rejected request leaves the sequence gapless.

CODING_STANDARDS.md on GitHub

retro-output.md to pełny tekst obu przebiegów retro i obu odpowiedzi śledzących z naszej sesji.

retro-output.md

# Retro output, session A (cb5884fb-bd6f-4684-8866-d0adc12ac26e)

## 1. `/retro` (resumed headless, 2026-10-23 10:39:44, $0.0658, 17.5 s, 5 turns)

Prompt typed: `/retro` -> transcript records `<command-name>/mattpocock-skills:retro</command-name>`. Tool calls: Skill(mattpocock-skills:writing-for-agents), Bash(ls -a; ls .github; ls .git/hooks | grep -v sample; cat tsconfig.json), Bash(find .claude -type f; cat .claude/settings*.json).

Verbatim:

> This session was smooth. The pass came out clean on the first typecheck and test run, and I found no `AGENTS.md`/`CLAUDE.md` or `CODING_STANDARDS.md` to prune. The candidates below are in order of severity.
> 
> **1. No guardrail runs the checks (automated checks)**
> - `package.json` already has `test` and `typecheck`, but nothing runs them: there's no `.github/` workflow and no pre-commit hook.
> - This session only stayed green because I ran both by hand. An agent, or a person, can commit a type error or a failing test.
> - **Fix:** add a CI job running `pnpm typecheck && pnpm test`, plus a pre-commit hook running the same. Neither needs prose.
> 
> **2. The migration rule is the one convention that could be missed (automated checks)**
> - The README says "any change to the stored shape bumps `schemaVersion` and adds a migration".
> - I found it only because I read `README.md` while working out the design. If I'd skipped it, nothing would have failed. Adding a field to `StoreData` without a migration still typechecks.
> - **Fix:** a test that fails when someone changes the stored shape without bumping the version. For example, snapshot the output of `migrate({})` and assert the snapshot's `schemaVersion` equals `CURRENT_SCHEMA_VERSION`. This is a deterministic check, so it should replace the README sentence rather than add to it.
> 
> **3. Adding a counter or store collection touches five places (navigation)**
> - Adding credit notes meant editing `types.ts`, `json-store.ts` (the `empty()` function), `migrations.ts` (the migration, plus the fallback defaults at the bottom of `migrate`), `context.ts`, and a new repo file.
> - The `{ customer: 0, invoice: 0, invoiceNumber: 0 }` literal is duplicated in `json-store.ts` and `migrations.ts`. I had to find both with `grep`.
> - **Fix:** have `migrate` build its defaults from one shared `emptyData()`. That removes a hidden dependency rather than documenting it. A pointer in a steering file would cost context on every turn and go stale, so I wouldn't write one.
> 
> **4. Nothing for the reviewer to enforce (coding standards)**
> - There's no `CODING_STANDARDS.md`. The README's conventions are mostly mechanical: integer cents, domain functions that don't mutate their input, and which error type maps to which status.
> - A reviewer agent would have no judgement-call rules to apply. I wouldn't add any until a real review miss shows one is needed.
> 
> **5. Tool economy and information access: nothing to change**
> - My one failed Bash call (a rejected heredoc) cost a retry, but that was my command and not the tooling.
> - I had everything I needed, since the tests call `createApp().handle` directly with no server or logs to tee.
> 
> I'd start with 1 and 2. They're small, mechanical, and would catch the likeliest future mistake. Want me to add the CI workflow, the pre-commit hook and the schema-version test?

## 2. Trace step (same session, 10:40:33, $0.0322, 17.1 s, 1 turn)

Prompt: "For each candidate, quote the moment of this session's transcript that backs it; drop any candidate you cannot trace to a specific moment."

Verbatim:

> Two of the five candidates have no support in the transcript, and I got a detail wrong in a third. Here is each one against what actually happened.
> 
> **1. No guardrail: kept**
> - The moment is my `ls -a; ls .github 2>/dev/null; ls .git/hooks | grep -v sample` command. The listing shows `.claude .git .gitignore data node_modules package.json … vitest.config.ts`. There is no `.github`, and the hooks `grep` printed nothing.
> - It isn't a mistake I made, since my own `pnpm typecheck` and `pnpm test` run came back clean. It's a repo-state finding: the checks exist as scripts and nothing runs them.
> 
> **2. Migration rule has no check: dropped**
> - I can't point to a moment where I missed or nearly missed a migration. I read `migrations.ts` in my first big `cat`, before I'd seen the README. I would have found the migration step either way, so my claim that I found it only through the README was wrong.
> - "Nothing would have failed if I'd skipped it" is a hypothetical, not something that happened.
> 
> **3. Five places to touch for a new collection: kept, but weaker than I said**
> - The moment is my batch of edits to `types.ts`, `json-store.ts`, `migrations.ts` and `context.ts`. Two of them changed the same literal, `{ customer: 0, invoice: 0, invoiceNumber: 0 }`, which now reads `…, creditNote: 0`. It appears in both `json-store.ts` and the fallback in `migrate`.
> - I said I "had to find both with `grep`". That's wrong. I never ran one, since the `grep` was in the command that was rejected. I already knew both locations from reading the files, and the edits went through without friction.
> - The duplicated literal is real but caused no trouble. I'd rate it low severity.
> 
> **4. No `CODING_STANDARDS.md`: dropped**
> - The only moment is the `git ls-files` output showing the file doesn't exist. No review step happened in this session and no reviewer missed anything.
> - "I wouldn't add any until a real review miss shows one is needed" was my own opinion, not something the session showed.
> 
> **5. Tool economy: dropped as a finding**
> - The moment is my first Bash call being rejected with `Contains brace with quote character (expansion obfuscation)`. It cost one retry, and I switched to Write and Edit.
> - It was a one-off, and I can't tell from the transcript whether the harness or my heredoc-in-Python approach was at fault. I don't think it justifies a change.
> 
> That leaves candidate 1 as the only solid finding and candidate 3 as a minor one. For 1, I can add a CI workflow and a pre-commit hook that both run `pnpm typecheck && pnpm test`.

## 3. Second `/retro`, with the defect reported by the developer (same session, 10:41:10, $0.0491, 23.1 s, 1 turn, no tool call; it skipped the writing-for-agents reload)

Prompt: `/retro Finance tested this build after the session: they sent a credit note that was too big (rejected, fine), and the next valid credit note came out CN-0004 where CN-0002 was due. Rejected requests burn credit-note numbers. Don't fix the code; run the retro on this session with that failure in mind.`

Verbatim:

> I'm skipping the style-guide reload because it's already in this session. The cause is in my own code, and I traced each finding to a specific moment.
> 
> **What happened**
> - In `issueCreditNote` (`src/http/handlers/invoices.ts`) I call `ctx.store.nextId("creditNote")` first and `createCreditNote(...)` second. `nextId` persists the counter immediately, and `createCreditNote` is what throws the 409 for an over-limit amount. So a rejected request still burns a number.
> - I copied the order from the existing `/issue` handler, which I had read. It does `const n = ctx.store.nextId("invoiceNumber"); const issued = issue(current, ...)`, and `issue()` throws if the invoice isn't a draft. So issuing a non-draft invoice probably burns an `INV-` number the same way. I haven't run that, only read it.
> 
> **1. A test that would have caught it: I wrote the scenario and skipped the assertion (automated checks)**
> - The moment is the test I wrote: "rejects bad amounts (400) and amounts above what is left (409)".
>   ```
>   await app.handle("POST", ..., { amount: 8_000 });
>   expect((await app.handle("POST", ..., { amount: 1_001 })).status).toBe(409);
>   expect((await app.handle("POST", ..., { amount: 1_000 })).status).toBe(201);
>   ```
>   That is exactly Finance's sequence: accept, reject, accept. I only checked status codes, never the number on the last note, which comes out as `CN-0003`.
> - The "numbers credit notes sequentially" test only covers two successful requests in a row.
> - **Fix:** add a test that each numbered sequence (`INV-`, `CN-`) stays gapless after rejected requests. Run it over both sequences, which also exposes the `/issue` case.
> - **Rule:** when a test reaches a failure path, assert the state afterwards, not just the status code.
> 
> **2. `nextId` looks pure but isn't (navigation)**
> - In `json-store.ts`, `nextId(kind)` runs `this.update(...)`, so every call writes to the counter and persists it. The `Store` type in `json-store.ts` has only the signature `nextId(kind: keyof Counters): number;`, with no comment about the side effect.
> - Nothing at the call site tells you to allocate only after validation. This is a gotcha no config reveals, so a short doc comment on `nextId` is worth its cost. Something like: "Consumes the number even if the caller then fails; call it only after validation."
> - Keep it as a comment on `nextId`, not a steering-file line. It matters only to someone calling `nextId`, and it can't go stale there.
> 
> **3. The gapless-numbering convention isn't written down (coding standards)**
> - The README's "Conventions" list has cents, immutability, error-to-status mapping, and migrations. It says nothing about invoice or credit-note numbers being gapless, though the request ("numbered `CN-0001`, `CN-0002`...") implies it.
> - This is partly a judgement call: reviewers need to know that numbers are allocated after validation. One README line would do. Finding 1's test is the deterministic check; the README line explains why the test exists.
> 
> **4. Missing CI, from the first retro: still real, but it wouldn't have helped here**
> - My own typecheck and tests passed, so a CI job would also have passed. I'm keeping it as a separate, unrelated finding, not as a cause of this failure.
> 
> **5. My summary stated the rules but didn't test them**
> - I told you "Rules I chose" and flagged the two-update void risk, but never exercised a rejection followed by a success. The summary read as complete when that path was untested. This is a process gap, and finding 1 is the fix.
> 
> I'd start with 1 and 2. I haven't touched the code, as you asked.

## 4. Trace step on the second retro (same session, 10:41:43, $0.0498, 33.4 s, 1 turn)

Prompt: same trace prompt as section 2.

Verbatim:

> I traced each candidate again. Two survive on firm evidence, two survive but with a gap I should state, and one is dropped.
> 
> **1. Test asserts status but not the number: kept, firm**
> - The moment is the test I wrote in `test/credit-notes.test.ts`:
>   ```
>   await app.handle("POST", `/invoices/${id}/credit-notes`, { amount: 8_000 });
>   expect((await app.handle("POST", `/invoices/${id}/credit-notes`, { amount: 1_001 })).status).toBe(409);
>   expect((await app.handle("POST", `/invoices/${id}/credit-notes`, { amount: 1_000 })).status).toBe(201);
>   ```
>   That is accept, reject, accept, with only status codes checked. By my reading of the handler, the last note comes out as `CN-0003`. I derived that and haven't run it.
> - The adjacent test, "numbers credit notes sequentially…", covers two successes in a row and never a rejection.
> - The cause, which I only read and haven't run, is this in the handler I wrote:
>   ```
>   const id = ctx.store.nextId("creditNote");
>   const note = createCreditNote(invoice, existing, amount, …
>   ```
>   That order matches the existing issue handler, which I read:
>   ```
>   const n = ctx.store.nextId("invoiceNumber");
>   const issued = issue(current, `INV-…`, ctx.now());
>   ```
>   and `issue()` throws `ConflictError` for non-drafts. So the `INV-` sequence very likely has the same leak. I haven't run that either.
> 
> **2. `nextId` has no warning about its side effect: kept, firm on the facts**
> - The moment is the `Store` type I read in `json-store.ts`. `update` has a comment ("Apply a change and persist it (when file-backed)."), while `nextId(kind: keyof Counters): number;` has none. Its implementation calls `this.update(...)`, so it persists immediately.
> - The `/issue` call site I copied has no comment either.
> - I can't show that a comment would have changed what I did, because I never weighed the ordering at all. I copied it. The comment is a bet on the next caller, not a proven fix.
> 
> **3. Gapless numbering isn't written in the README: kept, weaker**
> - The moment is the `README.md` output I read before writing the handler. Its Conventions list covers cents, no mutation, error-to-status mapping and `schemaVersion`. It has no line about numbers.
> - So the agent doing the implementation, meaning me, read the conventions and found nothing on this.
> - I overstated one thing last turn. Your request said "numbered `CN-0001`, `CN-0002`...", and I said that implies gapless numbers. That was my inference, not your words. Finance has now confirmed it as a requirement, but nothing in the original request stated it.
> 
> **4. No CI or pre-commit hook: kept, unrelated to this failure**
> - The moment is my `ls -a; ls .github 2>/dev/null; ls .git/hooks | grep -v sample` output, which showed no `.github` and no hooks.
> - It wouldn't have caught this. My own run ended `Tests 42 passed (42)`, and CI would have passed too.
> 
> **5. "My summary stated rules without testing them": dropped**
> - I can quote the summary ("Rules I chose", plus the line about the void being two separate store updates). But it describes my behaviour, not a change to the environment, and finding 1 already covers the underlying gap. Keeping it would count one moment twice.
> 
> The order of importance is 1, 2, then 3. Finding 4 stays on the list but belongs to a separate piece of work. I still haven't changed any code.

retro-output.md on GitHub

doctor-prompt-audit.md to prompt audit puszczony bez ścieżki, a potem ze ścieżką. Pokazuje pułapkę ścieżki.

doctor-prompt-audit.md

# `/doctor prompt-audit` (no path) on the ledgerly copy, session 26612b59-9edd-493b-a397-fb54300fa037

# Prompt audit: Claude Code configuration for ledgerly

**Assumptions**
- **Target model:** Claude Sonnet 5.5, the model running this session. A skill that writes prompts for other models (`prompt-master`) is audited for its Claude-facing text only.
- **Scope:** only the Claude Code configuration that loads into this project, as you specified. I proposed no edits to plugin files.
- **Settings and secrets:** I did not read `.claude/settings.json`, `.mcp.json` or `~/.claude.json`.
- **Edits are not applied.** Every edit below touches `~/.claude/`, so it **affects all projects**.
- **Dependency not verified:** I could not verify that `~/.claude` is under git, so I used no `git blame`. No hunk below relies on history.

**Inventory**
- **Project files:** none. The project root has no `CLAUDE.md`, `CLAUDE.local.md`, `AGENTS.md` or `.claude/` instruction files. The ancestors `/path/to/work` and `/private/tmp` have none either.
- **Managed policy:** no managed-policy `CLAUDE.md` exists.
- **User level:**
  - `~/.claude/CLAUDE.md`, which imports `~/.claude/RTK.md`.
  - `~/.claude/rules/context7.md`.
  - 27 skills under `~/.claude/skills/*/SKILL.md`.
  - There are no `commands/`, `agents/` or `output-styles/` folders.
- **Plugins:** `caveman`, `marketing`, `cowork-plugin-management` and `gleam-reels` are installed. I did not audit them in depth, and they have no findings or edits.
- **Coverage gap:** I read `CLAUDE.md`, `RTK.md`, the rule, `context7-mcp`, most of `prompt-master`, the relevant parts of `graphify`, and the top of `agent-reach`. I covered the other skills (Cloudflare, HyperFrames, browser, media) with signal greps and frontmatter only. I did not read their `references/` subfiles.
- **Possible mismatch:** this session's skill list shows none of the `~/.claude/skills/*` entries. These files may not be loading in this project, so the skill findings may not affect it.


## Findings of the first run

The audit without a path found no project instruction files and went on to audit the user-level files under the home folder instead: six proposed edits and four flags, all about files outside this repository, none applied. That part is left out of this copy because it concerns one developer's personal configuration, not the project.

# Second run: `/doctor prompt-audit CODING_STANDARDS.md` (session 9b5f0cd5-1701-498e-8d05-0355c7f1ece6)

## Prompt audit: `CODING_STANDARDS.md`

**Assumptions**
- **Scope:** only `CODING_STANDARDS.md`, which the request names. The inventory found no `CLAUDE.md`, `AGENTS.md`, rule files, skills, commands or subagents in the repo. `.claude/settings.json` exists but I did not read it, per the audit rules.
- **Target model:** Claude Sonnet 5.5, the model running this audit. The file is read by the coding agent, not by application code.
- **Group 4 (request config and architecture):** not applicable. The file is an agent instruction file and has no request-building code.

**Result: the file is clean.** It has one line, so there is nothing to change and the proposed diff is empty.

**Inventory:** `CODING_STANDARDS.md` has one rule at line 3: "Take a sequence number (`nextId`) only once every validation has passed, so a rejected request leaves the sequence gapless."

**Checks**

| Group | Findings |
|---|---|
| 1 Dated prompt text | 0. The rule has no emphasis, hedging, scaffold or step list. It states a reason, so it is context the model can't know, not a prohibition without provenance. |
| 2 Brittle config files | 0. `git blame` puts the line in `adaa593`, the retro commit that followed the credit-note session. It encodes a failure that actually happened, not a one-off stumble. |
| 3 Tool descriptions | Not applicable. |
| 4 Request config and architecture | Not applicable. |

Group 2 also covers stale facts. `nextId` is still defined (`src/store/json-store.ts:11,52`) and the sequence kinds it names still exist. No other instruction file ranks on the same point, so there is no conflict.

**One thing outside the audit:** the rule is violated in the code. `src/http/handlers/invoices.ts:44` calls `ctx.store.nextId("invoiceNumber")` before `issue()` runs. `issue()` throws `ConflictError` for any non-draft invoice (`src/domain/invoice.ts:42-44`). Issuing an already-issued, paid or void invoice therefore consumes an invoice number and leaves a gap. The fix is to validate first, or to pass an allocator into `issue()` the way `createCreditNote` takes `allocate`. I didn't check `customers.ts:8` or `credit-note.ts`.

This is a code bug, not a prompt problem, and the rule is working as intended. Keep it, and consider an enforcing test: `test/numbering.test.ts` may only cover credit notes. I haven't edited anything.

doctor-prompt-audit.md on GitHub

run-session.sh puszcza jedną turę Claude Code w trybie headless w izolowanej konfiguracji tylko z projektem, z allow-listą. Zmień linię env na własną.

run-session.sh

#!/usr/bin/env bash
# Usage: run-session.sh <workdir> <out.json> <prompt> [resume-session-id]
# One headless Claude Code turn with an isolated project-only setup and an allow-list.
set -uo pipefail
W="$1"; OUT="$2"; PROMPT="$3"; SID="${4:-}"
source ./env.sh  # your own env: unset CLAUDE* variables, optionally CLAUDE_CODE_DISABLE_AUTO_MEMORY=1
ALLOWED="Read,Edit,Write,MultiEdit,Glob,Grep,Skill,TodoWrite,Task,Agent,Bash(node:*),Bash(npm:*),Bash(pnpm:*),Bash(npx vitest:*),Bash(npx tsc:*),Bash(tsc:*),Bash(git status:*),Bash(git diff:*),Bash(git log:*),Bash(git add:*),Bash(git commit:*),Bash(git checkout -b:*),Bash(ls:*),Bash(cat:*),Bash(mkdir:*),Bash(head:*),Bash(tail:*),Bash(grep:*),Bash(wc:*),Bash(gh:*)"
DIS="AskUserQuestion,EnterPlanMode,ExitPlanMode,EnterWorktree,ExitWorktree,WebFetch,WebSearch"
ARGS=(-p "$PROMPT")
[ -n "$SID" ] && ARGS+=(--resume "$SID")
cd "$W" || exit 1
T0=$(date +%s)
claude "${ARGS[@]}" --model claude-sonnet-5-5 --permission-mode acceptEdits --output-format json \
  --allowedTools "$ALLOWED" --disallowedTools "$DIS" --setting-sources project --strict-mcp-config \
  > "$OUT" 2> "$OUT.stderr" < /dev/null
RC=$?
echo "rc=$RC wall=$(( $(date +%s) - T0 ))s" | tee "$OUT.wall"
python3 -c "import json,sys;d=json.load(open(sys.argv[1]));print({k:d.get(k) for k in ('session_id','total_cost_usd','duration_ms','num_turns','is_error','subtype')})" "$OUT"

run-session.sh on GitHub

oracle.sh puszcza ukryty test księgowy, pięć wymogów sprawdzanych spoza sesji, na kopii roboczej. Wskaż go na własne ukryte testy.

oracle.sh

#!/usr/bin/env bash
# Usage: oracle.sh <workdir> <out.json>  -- the hidden finance test for the credit-note task, run from OUTSIDE the work copy.
H=/path/to/hidden-tests
W="$1"; OUT="$2"
cd "$H" && env -u CLAUDECODE WORK="$W" BASE="$(git -C "$W" rev-list --max-parents=0 HEAD | head -1)" TASK=F2 \
  "$H/node_modules/.bin/vitest" run --reporter=json --outputFile="$OUT" > "$OUT.log" 2>&1
python3 - "$OUT" <<'PY'
import json,sys
j=json.load(open(sys.argv[1]))
for tr in j["testResults"]:
    for a in tr["assertionResults"]:
        print(a["status"].upper(), a["title"]); 
        if a["status"]!="passed": print("   ", " ".join(a.get("failureMessages") or [])[:500].replace("\n"," | "))
PY

oracle.sh on GitHub

sessionA-F2.diff to kod sesji, która wypuściła buga, wraz z poprawką.

sessionA-F2.diff

diff --git a/README.md b/README.md
index 890f13c..ae1e4f9 100644
--- a/README.md
+++ b/README.md
@@ -27,4 +27,8 @@ pnpm typecheck   # tsc --noEmit
 
 ## Invoice lifecycle
 
-`draft` → (`issue`) → `open` → (`pay`) → `paid`; `draft`/`open` → (`void`) → `void`.
+`draft` → (`issue`) → `open` → (`pay`) → `paid`; `draft`/`open`/`paid` → (`void`) → `void`.
+
+Credit notes (`POST`/`GET /invoices/:id/credit-notes`, numbered `CN-0001`, ...) can be issued against
+`open` or `paid` invoices, up to the invoice total minus earlier credit notes. Open invoices' credits
+reduce the outstanding report. Voiding a paid invoice issues a credit note for whatever is left.
diff --git a/src/domain/credit-note.ts b/src/domain/credit-note.ts
new file mode 100644
index 0000000..9a48b40
--- /dev/null
+++ b/src/domain/credit-note.ts
@@ -0,0 +1,43 @@
+import { ConflictError, ValidationError } from "./errors";
+import { computeTotals, type Invoice } from "./invoice";
+import { assertCents, type Cents, type Currency, sum } from "./money";
+
+export type CreditNote = {
+  id: string;
+  /** CN-0001, ... */
+  number: string;
+  invoiceId: string;
+  currency: Currency;
+  /** cents, always positive */
+  amount: Cents;
+  createdAt: string;
+};
+
+export function parseCreditNoteAmount(body: unknown): Cents {
+  if (typeof body !== "object" || body === null) {
+    throw new ValidationError("body must be an object");
+  }
+  return assertCents((body as Record<string, unknown>).amount, "amount", { min: 1 });
+}
+
+/** What is still creditable on an invoice: its total minus the credit notes already issued. */
+export function remainingCredit(invoice: Invoice, notes: CreditNote[]): Cents {
+  return computeTotals(invoice).total - sum(notes.map((n) => n.amount));
+}
+
+export function createCreditNote(
+  invoice: Invoice,
+  existing: CreditNote[],
+  amount: Cents,
+  ids: { id: string; number: string },
+  now: Date,
+): CreditNote {
+  if (invoice.status !== "open" && invoice.status !== "paid") {
+    throw new ConflictError(`invoice ${invoice.id} is ${invoice.status}, only open or paid invoices can be credited`);
+  }
+  const remaining = remainingCredit(invoice, existing);
+  if (amount > remaining) {
+    throw new ConflictError(`credit note of ${amount} exceeds the ${remaining} still creditable on invoice ${invoice.id}`);
+  }
+  return { ...ids, invoiceId: invoice.id, currency: invoice.currency, amount, createdAt: now.toISOString() };
+}
diff --git a/src/domain/invoice.ts b/src/domain/invoice.ts
index 5b69fc9..1a3967b 100644
--- a/src/domain/invoice.ts
+++ b/src/domain/invoice.ts
@@ -52,8 +52,9 @@ export function markPaid(invoice: Invoice, now: Date): Invoice {
   return { ...invoice, status: "paid", paidAt: now.toISOString() };
 }
 
+/** Paid invoices can be voided too, but the caller must credit what is left on them first. */
 export function voidInvoice(invoice: Invoice, now: Date): Invoice {
-  if (invoice.status === "paid" || invoice.status === "void") {
+  if (invoice.status === "void") {
     throw new ConflictError(`invoice ${invoice.id} is ${invoice.status} and cannot be voided`);
   }
   return { ...invoice, status: "void", voidedAt: now.toISOString() };
diff --git a/src/http/context.ts b/src/http/context.ts
index c0a89d3..38d7ffa 100644
--- a/src/http/context.ts
+++ b/src/http/context.ts
@@ -1,5 +1,6 @@
 import type { Store } from "../store/json-store";
 import { customerRepo } from "../store/customer-repo";
+import { creditNoteRepo } from "../store/credit-note-repo";
 import { invoiceRepo } from "../store/invoice-repo";
 
 export type AppContext = {
@@ -7,8 +8,9 @@ export type AppContext = {
   now: () => Date;
   customers: ReturnType<typeof customerRepo>;
   invoices: ReturnType<typeof invoiceRepo>;
+  creditNotes: ReturnType<typeof creditNoteRepo>;
 };
 
 export function createContext(store: Store, now: () => Date = () => new Date()): AppContext {
-  return { store, now, customers: customerRepo(store), invoices: invoiceRepo(store) };
+  return { store, now, customers: customerRepo(store), invoices: invoiceRepo(store), creditNotes: creditNoteRepo(store) };
 }
diff --git a/src/http/handlers/invoices.ts b/src/http/handlers/invoices.ts
index 09959e1..17b3910 100644
--- a/src/http/handlers/invoices.ts
+++ b/src/http/handlers/invoices.ts
@@ -1,3 +1,4 @@
+import { type CreditNote, createCreditNote, parseCreditNoteAmount, remainingCredit } from "../../domain/credit-note";
 import { ValidationError } from "../../domain/errors";
 import { type Invoice, type InvoiceStatus, issue, markPaid, voidInvoice } from "../../domain/invoice";
 import { parseNewInvoice } from "../../domain/validation";
@@ -51,8 +52,33 @@ export function invoiceRoutes(router: Router, ctx: AppContext): void {
     return { status: 200, body: invoiceView(ctx.invoices.save(paid)) };
   });
 
+  /** Voiding a paid invoice credits whatever is left on it, so the books stay balanced. */
   router.on("POST", "/invoices/:id/void", ({ params }) => {
-    const voided = voidInvoice(ctx.invoices.get(params.id), ctx.now());
+    const current = ctx.invoices.get(params.id);
+    const now = ctx.now();
+    const voided = voidInvoice(current, now);
+    if (current.status === "paid") {
+      const left = remainingCredit(current, ctx.creditNotes.listForInvoice(current.id));
+      if (left > 0) issueCreditNote(current, left);
+    }
     return { status: 200, body: invoiceView(ctx.invoices.save(voided)) };
   });
+
+  router.on("POST", "/invoices/:id/credit-notes", ({ params, body }) => {
+    const invoice = ctx.invoices.get(params.id);
+    const amount = parseCreditNoteAmount(body);
+    return { status: 201, body: issueCreditNote(invoice, amount) };
+  });
+
+  router.on("GET", "/invoices/:id/credit-notes", ({ params }) => {
+    const invoice = ctx.invoices.get(params.id);
+    return { status: 200, body: ctx.creditNotes.listForInvoice(invoice.id) };
+  });
+
+  function issueCreditNote(invoice: Invoice, amount: number): CreditNote {
+    const existing = ctx.creditNotes.listForInvoice(invoice.id);
+    const id = ctx.store.nextId("creditNote");
+    const note = createCreditNote(invoice, existing, amount, { id: `cn_${id}`, number: `CN-${String(id).padStart(4, "0")}` }, ctx.now());
+    return ctx.creditNotes.insert(note);
+  }
 }
diff --git a/src/http/handlers/reports.ts b/src/http/handlers/reports.ts
index 19262c9..c84089a 100644
--- a/src/http/handlers/reports.ts
+++ b/src/http/handlers/reports.ts
@@ -1,4 +1,5 @@
-import { computeTotals, isOverdue } from "../../domain/invoice";
+import { remainingCredit } from "../../domain/credit-note";
+import { isOverdue } from "../../domain/invoice";
 import type { Currency } from "../../domain/money";
 import type { AppContext } from "../context";
 import type { Router } from "../router";
@@ -11,8 +12,8 @@ export function reportRoutes(router: Router, ctx: AppContext): void {
     let count = 0;
     let overdue = 0;
     for (const invoice of ctx.invoices.list({ status: "open" })) {
-      const { total } = computeTotals(invoice);
-      totals[invoice.currency] = (totals[invoice.currency] ?? 0) + total;
+      const owed = remainingCredit(invoice, ctx.creditNotes.listForInvoice(invoice.id));
+      totals[invoice.currency] = (totals[invoice.currency] ?? 0) + owed;
       count += 1;
       if (isOverdue(invoice, now)) overdue += 1;
     }
diff --git a/src/store/credit-note-repo.ts b/src/store/credit-note-repo.ts
new file mode 100644
index 0000000..c922142
--- /dev/null
+++ b/src/store/credit-note-repo.ts
@@ -0,0 +1,14 @@
+import type { CreditNote } from "../domain/credit-note";
+import type { Store } from "./json-store";
+
+export function creditNoteRepo(store: Store) {
+  return {
+    listForInvoice(invoiceId: string): CreditNote[] {
+      return store.read().creditNotes.filter((n) => n.invoiceId === invoiceId);
+    },
+    insert(note: CreditNote): CreditNote {
+      store.update((d) => ({ ...d, creditNotes: [...d.creditNotes, note] }));
+      return note;
+    },
+  };
+}
diff --git a/src/store/json-store.ts b/src/store/json-store.ts
index b404c51..99205b7 100644
--- a/src/store/json-store.ts
+++ b/src/store/json-store.ts
@@ -13,9 +13,10 @@ export type Store = {
 function empty(): StoreData {
   return {
     schemaVersion: CURRENT_SCHEMA_VERSION,
-    counters: { customer: 0, invoice: 0, invoiceNumber: 0 },
+    counters: { customer: 0, invoice: 0, invoiceNumber: 0, creditNote: 0 },
     customers: [],
     invoices: [],
+    creditNotes: [],
   };
 }
 
diff --git a/src/store/migrations.ts b/src/store/migrations.ts
index c8b73a9..91d4f99 100644
--- a/src/store/migrations.ts
+++ b/src/store/migrations.ts
@@ -1,6 +1,6 @@
 import type { StoreData } from "./types";
 
-export const CURRENT_SCHEMA_VERSION = 1;
+export const CURRENT_SCHEMA_VERSION = 2;
 
 type RawData = Record<string, unknown> & { schemaVersion?: number };
 type Migration = (data: RawData) => RawData;
@@ -21,9 +21,18 @@ const v0ToV1: Migration = (data) => {
   };
 };
 
+/** v1 -> v2: credit notes (a `creditNotes` list and a `creditNote` counter). */
+const v1ToV2: Migration = (data) => ({
+  ...data,
+  schemaVersion: 2,
+  counters: { creditNote: 0, ...(data.counters as Record<string, number> | undefined) },
+  creditNotes: (data.creditNotes as unknown[] | undefined) ?? [],
+});
+
 /** migrations[n] upgrades a file from version n to n + 1. */
 const migrations: Record<number, Migration> = {
   0: v0ToV1,
+  1: v1ToV2,
 };
 
 export function migrate(raw: unknown): StoreData {
@@ -43,8 +52,9 @@ export function migrate(raw: unknown): StoreData {
   }
   return {
     schemaVersion: CURRENT_SCHEMA_VERSION,
-    counters: (data.counters as StoreData["counters"]) ?? { customer: 0, invoice: 0, invoiceNumber: 0 },
+    counters: (data.counters as StoreData["counters"]) ?? { customer: 0, invoice: 0, invoiceNumber: 0, creditNote: 0 },
     customers: (data.customers as StoreData["customers"]) ?? [],
     invoices: (data.invoices as StoreData["invoices"]) ?? [],
+    creditNotes: (data.creditNotes as StoreData["creditNotes"]) ?? [],
   };
 }
diff --git a/src/store/types.ts b/src/store/types.ts
index 222b191..a9d7277 100644
--- a/src/store/types.ts
+++ b/src/store/types.ts
@@ -1,7 +1,8 @@
+import type { CreditNote } from "../domain/credit-note";
 import type { Customer } from "../domain/customer";
 import type { Invoice } from "../domain/invoice";
 
-export type Counters = { customer: number; invoice: number; invoiceNumber: number };
+export type Counters = { customer: number; invoice: number; invoiceNumber: number; creditNote: number };
 
 /** The shape of the JSON file at CURRENT_SCHEMA_VERSION. */
 export type StoreData = {
@@ -9,4 +10,5 @@ export type StoreData = {
   counters: Counters;
   customers: Customer[];
   invoices: Invoice[];
+  creditNotes: CreditNote[];
 };
diff --git a/test/credit-notes.test.ts b/test/credit-notes.test.ts
new file mode 100644
index 0000000..f841a3c
--- /dev/null
+++ b/test/credit-notes.test.ts
@@ -0,0 +1,94 @@
+import { describe, expect, it } from "vitest";
+import { openStore } from "../src/store/json-store";
+import { migrate } from "../src/store/migrations";
+import { seedCustomer, seedOpenInvoice, testApp } from "./helpers";
+
+async function setup(opts: { unitPrice?: number; discount?: number } = {}) {
+  const app = testApp();
+  const customerId = await seedCustomer(app);
+  const id = await seedOpenInvoice(app, { customerId, unitPrice: opts.unitPrice ?? 10_000, discount: opts.discount });
+  return { app, id };
+}
+
+describe("credit notes", () => {
+  it("numbers credit notes sequentially and lists them per invoice", async () => {
+    const { app, id } = await setup();
+    const first = await app.handle("POST", `/invoices/${id}/credit-notes`, { amount: 2_500 });
+    const second = await app.handle("POST", `/invoices/${id}/credit-notes`, { amount: 1_000 });
+    expect(first.status).toBe(201);
+    expect(first.body).toMatchObject({ number: "CN-0001", invoiceId: id, amount: 2_500, currency: "EUR" });
+    expect(second.body).toMatchObject({ number: "CN-0002" });
+    const list = await app.handle("GET", `/invoices/${id}/credit-notes`);
+    expect((list.body as { number: string }[]).map((n) => n.number)).toEqual(["CN-0001", "CN-0002"]);
+  });
+
+  it("rejects bad amounts (400) and amounts above what is left (409)", async () => {
+    const { app, id } = await setup({ discount: 1_000 });
+    for (const amount of [0, -5, 1.5, "10", undefined]) {
+      expect((await app.handle("POST", `/invoices/${id}/credit-notes`, { amount })).status).toBe(400);
+    }
+    await app.handle("POST", `/invoices/${id}/credit-notes`, { amount: 8_000 });
+    expect((await app.handle("POST", `/invoices/${id}/credit-notes`, { amount: 1_001 })).status).toBe(409);
+    expect((await app.handle("POST", `/invoices/${id}/credit-notes`, { amount: 1_000 })).status).toBe(201);
+  });
+
+  it("refuses drafts and unknown invoices", async () => {
+    const app = testApp();
+    const customerId = await seedCustomer(app);
+    const draft = await app.handle("POST", "/invoices", {
+      customerId,
+      currency: "EUR",
+      lines: [{ description: "x", quantity: 1, unitPrice: 100 }],
+    });
+    const id = (draft.body as { id: string }).id;
+    expect((await app.handle("POST", `/invoices/${id}/credit-notes`, { amount: 10 })).status).toBe(409);
+    expect((await app.handle("GET", "/invoices/inv_999/credit-notes")).status).toBe(404);
+  });
+
+  it("reduces the outstanding report for open invoices", async () => {
+    const { app, id } = await setup();
+    await app.handle("POST", `/invoices/${id}/credit-notes`, { amount: 4_000 });
+    const report = await app.handle("GET", "/reports/outstanding");
+    expect(report.body).toMatchObject({ totals: { EUR: 6_000 }, count: 1 });
+  });
+
+  it("voids a paid invoice by crediting what is left", async () => {
+    const { app, id } = await setup();
+    await app.handle("POST", `/invoices/${id}/pay`);
+    await app.handle("POST", `/invoices/${id}/credit-notes`, { amount: 3_000 });
+    const res = await app.handle("POST", `/invoices/${id}/void`);
+    expect(res.status).toBe(200);
+    expect(res.body).toMatchObject({ status: "void" });
+    const notes = (await app.handle("GET", `/invoices/${id}/credit-notes`)).body as { amount: number }[];
+    expect(notes.map((n) => n.amount)).toEqual([3_000, 7_000]);
+  });
+
+  it("voids a fully credited paid invoice without another note", async () => {
+    const { app, id } = await setup();
+    await app.handle("POST", `/invoices/${id}/pay`);
+    await app.handle("POST", `/invoices/${id}/credit-notes`, { amount: 10_000 });
+    expect((await app.handle("POST", `/invoices/${id}/void`)).status).toBe(200);
+    const notes = (await app.handle("GET", `/invoices/${id}/credit-notes`)).body as unknown[];
+    expect(notes).toHaveLength(1);
+  });
+
+  it("refuses credit notes on void invoices and double voids", async () => {
+    const { app, id } = await setup();
+    await app.handle("POST", `/invoices/${id}/pay`);
+    await app.handle("POST", `/invoices/${id}/void`);
+    expect((await app.handle("POST", `/invoices/${id}/credit-notes`, { amount: 1 })).status).toBe(409);
+    expect((await app.handle("POST", `/invoices/${id}/void`)).status).toBe(409);
+  });
+
+  it("migrates a v1 file by adding the credit note list and counter", () => {
+    const data = migrate({
+      schemaVersion: 1,
+      counters: { customer: 1, invoice: 1, invoiceNumber: 1 },
+      customers: [],
+      invoices: [],
+    });
+    expect(data.creditNotes).toEqual([]);
+    expect(data.counters).toEqual({ customer: 1, invoice: 1, invoiceNumber: 1, creditNote: 0 });
+    expect(openStore().nextId("creditNote")).toBe(1);
+  });
+});
diff --git a/test/invoice.test.ts b/test/invoice.test.ts
index 85202f2..4ad9677 100644
--- a/test/invoice.test.ts
+++ b/test/invoice.test.ts
@@ -53,9 +53,10 @@ describe("invoice domain", () => {
     expect(() => markPaid(draft({ status: "void" }), NOW)).toThrow(ConflictError);
   });
 
-  it("voids drafts and open invoices, never paid ones", () => {
+  it("voids drafts, open and paid invoices, never void ones", () => {
     expect(voidInvoice(draft(), NOW).status).toBe("void");
-    expect(() => voidInvoice(draft({ status: "paid" }), NOW)).toThrow(ConflictError);
+    expect(voidInvoice(draft({ status: "paid" }), NOW).status).toBe("void");
+    expect(() => voidInvoice(draft({ status: "void" }), NOW)).toThrow(ConflictError);
   });
 
   it("knows when an open invoice is overdue", () => {

sessionA-F2.diff on GitHub

sessionB-F2.diff to kod świeżej sesji, która powtórzyła to samo żądanie.

sessionB-F2.diff

diff --git a/README.md b/README.md
index 890f13c..3aa7a58 100644
--- a/README.md
+++ b/README.md
@@ -28,3 +28,5 @@ pnpm typecheck   # tsc --noEmit
 ## Invoice lifecycle
 
 `draft` → (`issue`) → `open` → (`pay`) → `paid`; `draft`/`open` → (`void`) → `void`.
+A `paid` invoice is voided by crediting whatever is left on it (credit notes `CN-0001`, ..., via
+`POST /invoices/:id/credit-notes` `{ "amount": cents }`; list with `GET`), then it becomes `void`.
diff --git a/src/domain/credit-note.ts b/src/domain/credit-note.ts
new file mode 100644
index 0000000..e2047c3
--- /dev/null
+++ b/src/domain/credit-note.ts
@@ -0,0 +1,39 @@
+import { ConflictError, ValidationError } from "./errors";
+import { computeTotals, type Invoice } from "./invoice";
+import { assertCents, type Cents, type Currency, sum } from "./money";
+
+export type CreditNote = {
+  id: string;
+  /** CN-0001, CN-0002, ... */
+  number: string;
+  invoiceId: string;
+  currency: Currency;
+  /** cents, always > 0 */
+  amount: Cents;
+  createdAt: string;
+};
+
+/** What can still be credited on an invoice: its total minus the credit notes already issued. */
+export function remainingCredit(invoice: Invoice, notes: CreditNote[]): Cents {
+  return computeTotals(invoice).total - sum(notes.map((n) => n.amount));
+}
+
+/** Checks a credit-note request against the invoice and returns the amount. Throws before any number is taken. */
+export function parseCreditAmount(body: unknown, invoice: Invoice, notes: CreditNote[]): Cents {
+  if (typeof body !== "object" || body === null) {
+    throw new ValidationError("body must be an object");
+  }
+  const amount = assertCents((body as Record<string, unknown>).amount, "amount", { min: 1 });
+  if (invoice.status !== "paid") {
+    throw new ConflictError(`invoice ${invoice.id} is ${invoice.status}, only paid invoices can be credited`);
+  }
+  const remaining = remainingCredit(invoice, notes);
+  if (amount > remaining) {
+    throw new ConflictError(`amount ${amount} exceeds the ${remaining} left to credit on invoice ${invoice.id}`);
+  }
+  return amount;
+}
+
+export function creditNumber(n: number): string {
+  return `CN-${String(n).padStart(4, "0")}`;
+}
diff --git a/src/domain/invoice.ts b/src/domain/invoice.ts
index 5b69fc9..60be8ac 100644
--- a/src/domain/invoice.ts
+++ b/src/domain/invoice.ts
@@ -52,8 +52,9 @@ export function markPaid(invoice: Invoice, now: Date): Invoice {
   return { ...invoice, status: "paid", paidAt: now.toISOString() };
 }
 
-export function voidInvoice(invoice: Invoice, now: Date): Invoice {
-  if (invoice.status === "paid" || invoice.status === "void") {
+/** A paid invoice can be voided only once it is fully credited (`fullyCredited`). */
+export function voidInvoice(invoice: Invoice, now: Date, opts: { fullyCredited?: boolean } = {}): Invoice {
+  if ((invoice.status === "paid" && !opts.fullyCredited) || invoice.status === "void") {
     throw new ConflictError(`invoice ${invoice.id} is ${invoice.status} and cannot be voided`);
   }
   return { ...invoice, status: "void", voidedAt: now.toISOString() };
diff --git a/src/http/context.ts b/src/http/context.ts
index c0a89d3..4b26d92 100644
--- a/src/http/context.ts
+++ b/src/http/context.ts
@@ -1,4 +1,5 @@
 import type { Store } from "../store/json-store";
+import { creditNoteRepo } from "../store/credit-note-repo";
 import { customerRepo } from "../store/customer-repo";
 import { invoiceRepo } from "../store/invoice-repo";
 
@@ -7,8 +8,15 @@ export type AppContext = {
   now: () => Date;
   customers: ReturnType<typeof customerRepo>;
   invoices: ReturnType<typeof invoiceRepo>;
+  creditNotes: ReturnType<typeof creditNoteRepo>;
 };
 
 export function createContext(store: Store, now: () => Date = () => new Date()): AppContext {
-  return { store, now, customers: customerRepo(store), invoices: invoiceRepo(store) };
+  return {
+    store,
+    now,
+    customers: customerRepo(store),
+    invoices: invoiceRepo(store),
+    creditNotes: creditNoteRepo(store),
+  };
 }
diff --git a/src/http/handlers/invoices.ts b/src/http/handlers/invoices.ts
index 09959e1..d393c34 100644
--- a/src/http/handlers/invoices.ts
+++ b/src/http/handlers/invoices.ts
@@ -1,3 +1,4 @@
+import { type CreditNote, creditNumber, parseCreditAmount, remainingCredit } from "../../domain/credit-note";
 import { ValidationError } from "../../domain/errors";
 import { type Invoice, type InvoiceStatus, issue, markPaid, voidInvoice } from "../../domain/invoice";
 import { parseNewInvoice } from "../../domain/validation";
@@ -51,8 +52,39 @@ export function invoiceRoutes(router: Router, ctx: AppContext): void {
     return { status: 200, body: invoiceView(ctx.invoices.save(paid)) };
   });
 
+  router.on("POST", "/invoices/:id/credit-notes", ({ params, body }) => {
+    const invoice = ctx.invoices.get(params.id);
+    const amount = parseCreditAmount(body, invoice, ctx.creditNotes.listForInvoice(invoice.id));
+    return { status: 201, body: ctx.creditNotes.insert(newCreditNote(ctx, invoice, amount)) };
+  });
+
+  router.on("GET", "/invoices/:id/credit-notes", ({ params }) => {
+    const invoice = ctx.invoices.get(params.id);
+    return { status: 200, body: ctx.creditNotes.listForInvoice(invoice.id) };
+  });
+
   router.on("POST", "/invoices/:id/void", ({ params }) => {
-    const voided = voidInvoice(ctx.invoices.get(params.id), ctx.now());
+    const current = ctx.invoices.get(params.id);
+    if (current.status !== "paid") {
+      return { status: 200, body: invoiceView(ctx.invoices.save(voidInvoice(current, ctx.now()))) };
+    }
+    // Paid invoice: credit whatever is left, then void it.
+    const left = remainingCredit(current, ctx.creditNotes.listForInvoice(current.id));
+    if (left > 0) ctx.creditNotes.insert(newCreditNote(ctx, current, left));
+    const voided = voidInvoice(current, ctx.now(), { fullyCredited: true });
     return { status: 200, body: invoiceView(ctx.invoices.save(voided)) };
   });
 }
+
+/** Takes the next number: call only once the amount has been validated. */
+function newCreditNote(ctx: AppContext, invoice: Invoice, amount: number): CreditNote {
+  const n = ctx.store.nextId("creditNote");
+  return {
+    id: `cn_${n}`,
+    number: creditNumber(n),
+    invoiceId: invoice.id,
+    currency: invoice.currency,
+    amount,
+    createdAt: ctx.now().toISOString(),
+  };
+}
diff --git a/src/store/credit-note-repo.ts b/src/store/credit-note-repo.ts
new file mode 100644
index 0000000..c922142
--- /dev/null
+++ b/src/store/credit-note-repo.ts
@@ -0,0 +1,14 @@
+import type { CreditNote } from "../domain/credit-note";
+import type { Store } from "./json-store";
+
+export function creditNoteRepo(store: Store) {
+  return {
+    listForInvoice(invoiceId: string): CreditNote[] {
+      return store.read().creditNotes.filter((n) => n.invoiceId === invoiceId);
+    },
+    insert(note: CreditNote): CreditNote {
+      store.update((d) => ({ ...d, creditNotes: [...d.creditNotes, note] }));
+      return note;
+    },
+  };
+}
diff --git a/src/store/json-store.ts b/src/store/json-store.ts
index e1daef5..03df910 100644
--- a/src/store/json-store.ts
+++ b/src/store/json-store.ts
@@ -14,9 +14,10 @@ export type Store = {
 function empty(): StoreData {
   return {
     schemaVersion: CURRENT_SCHEMA_VERSION,
-    counters: { customer: 0, invoice: 0, invoiceNumber: 0 },
+    counters: { customer: 0, invoice: 0, invoiceNumber: 0, creditNote: 0 },
     customers: [],
     invoices: [],
+    creditNotes: [],
   };
 }
 
diff --git a/src/store/migrations.ts b/src/store/migrations.ts
index c8b73a9..e8545db 100644
--- a/src/store/migrations.ts
+++ b/src/store/migrations.ts
@@ -1,6 +1,6 @@
 import type { StoreData } from "./types";
 
-export const CURRENT_SCHEMA_VERSION = 1;
+export const CURRENT_SCHEMA_VERSION = 2;
 
 type RawData = Record<string, unknown> & { schemaVersion?: number };
 type Migration = (data: RawData) => RawData;
@@ -21,9 +21,18 @@ const v0ToV1: Migration = (data) => {
   };
 };
 
+/** v1 -> v2: credit notes (`creditNotes` list and `counters.creditNote`). */
+const v1ToV2: Migration = (data) => ({
+  ...data,
+  schemaVersion: 2,
+  counters: { ...(data.counters as object), creditNote: 0 },
+  creditNotes: [],
+});
+
 /** migrations[n] upgrades a file from version n to n + 1. */
 const migrations: Record<number, Migration> = {
   0: v0ToV1,
+  1: v1ToV2,
 };
 
 export function migrate(raw: unknown): StoreData {
@@ -43,8 +52,9 @@ export function migrate(raw: unknown): StoreData {
   }
   return {
     schemaVersion: CURRENT_SCHEMA_VERSION,
-    counters: (data.counters as StoreData["counters"]) ?? { customer: 0, invoice: 0, invoiceNumber: 0 },
+    counters: (data.counters as StoreData["counters"]) ?? { customer: 0, invoice: 0, invoiceNumber: 0, creditNote: 0 },
     customers: (data.customers as StoreData["customers"]) ?? [],
     invoices: (data.invoices as StoreData["invoices"]) ?? [],
+    creditNotes: (data.creditNotes as StoreData["creditNotes"]) ?? [],
   };
 }
diff --git a/src/store/types.ts b/src/store/types.ts
index 222b191..a9d7277 100644
--- a/src/store/types.ts
+++ b/src/store/types.ts
@@ -1,7 +1,8 @@
+import type { CreditNote } from "../domain/credit-note";
 import type { Customer } from "../domain/customer";
 import type { Invoice } from "../domain/invoice";
 
-export type Counters = { customer: number; invoice: number; invoiceNumber: number };
+export type Counters = { customer: number; invoice: number; invoiceNumber: number; creditNote: number };
 
 /** The shape of the JSON file at CURRENT_SCHEMA_VERSION. */
 export type StoreData = {
@@ -9,4 +10,5 @@ export type StoreData = {
   counters: Counters;
   customers: Customer[];
   invoices: Invoice[];
+  creditNotes: CreditNote[];
 };
diff --git a/test/invoice.test.ts b/test/invoice.test.ts
index 85202f2..97ef4d9 100644
--- a/test/invoice.test.ts
+++ b/test/invoice.test.ts
@@ -53,9 +53,10 @@ describe("invoice domain", () => {
     expect(() => markPaid(draft({ status: "void" }), NOW)).toThrow(ConflictError);
   });
 
-  it("voids drafts and open invoices, never paid ones", () => {
+  it("voids drafts and open invoices, paid ones only when fully credited", () => {
     expect(voidInvoice(draft(), NOW).status).toBe("void");
     expect(() => voidInvoice(draft({ status: "paid" }), NOW)).toThrow(ConflictError);
+    expect(voidInvoice(draft({ status: "paid" }), NOW, { fullyCredited: true }).status).toBe("void");
   });
 
   it("knows when an open invoice is overdue", () => {
diff --git a/test/numbering.test.ts b/test/numbering.test.ts
index a97d189..1fa4dd8 100644
--- a/test/numbering.test.ts
+++ b/test/numbering.test.ts
@@ -20,3 +20,34 @@ describe("credit note numbering", () => {
     expect(next.body).toMatchObject({ number: "CN-0002" });
   });
 });
+
+describe("credit notes and voiding", () => {
+  it("lists credit notes and voids a paid invoice by crediting the rest", async () => {
+    const app = testApp();
+    const customerId = await seedCustomer(app);
+    const id = await seedOpenInvoice(app, { customerId, unitPrice: 10_000 });
+    await app.handle("POST", `/invoices/${id}/pay`);
+    await app.handle("POST", `/invoices/${id}/credit-notes`, { amount: 2_500 });
+
+    const voided = await app.handle("POST", `/invoices/${id}/void`);
+    expect(voided.status).toBe(200);
+    expect(voided.body).toMatchObject({ status: "void" });
+
+    const list = await app.handle("GET", `/invoices/${id}/credit-notes`);
+    expect((list.body as { number: string; amount: number }[]).map((n) => [n.number, n.amount])).toEqual([
+      ["CN-0001", 2_500],
+      ["CN-0002", 7_500],
+    ]);
+  });
+
+  it("rejects bad amounts and unpaid invoices", async () => {
+    const app = testApp();
+    const customerId = await seedCustomer(app);
+    const id = await seedOpenInvoice(app, { customerId });
+    const url = `/invoices/${id}/credit-notes`;
+    expect((await app.handle("POST", url, { amount: 100 })).status).toBe(409);
+    await app.handle("POST", `/invoices/${id}/pay`);
+    expect((await app.handle("POST", url, { amount: 0 })).status).toBe(400);
+    expect((await app.handle("POST", url, {})).status).toBe(400);
+  });
+});
diff --git a/test/store.test.ts b/test/store.test.ts
index a1bf345..82cc59f 100644
--- a/test/store.test.ts
+++ b/test/store.test.ts
@@ -31,7 +31,7 @@ describe("store", () => {
     writeFileSync(
       file,
       JSON.stringify({
-        counters: { customer: 1, invoice: 1, invoiceNumber: 0 },
+        counters: { customer: 1, invoice: 1, invoiceNumber: 0, creditNote: 0 },
         customers: [{ id: "cus_1", name: "Acme", email: "a@acme.io", createdAt: "2025-01-01T00:00:00.000Z" }],
         invoices: [{ id: "inv_1", customer: { id: "cus_1", name: "Acme" }, status: "draft" }],
       }),

sessionB-F2.diff on GitHub

Zrób to w poniedziałek

  • Zaktualizuj oficjalny marketplace, zainstaluj paczkę skilli w zakresie projektu i sprawdź, czy komenda retro pojawia się w nowej sesji.
  • Puść swoje prawdziwe zadanie w zwykłej sesji. Daj jej skończyć i zostaw sesję otwartą.
  • Puść retro w tej sesji, a potem jeszcze raz, z porażką, którą znalazłeś, wpisaną po komendzie.
  • Zadaj pytanie śledzące: "For each candidate, quote the moment of this session's transcript that backs it; drop any candidate you cannot trace to a specific moment."
  • Zatwierdzaj ocalałych po jednym do ich nośnika: kontrola dla błędu mechanicznego, linia standardów dla decyzji opartej na osądzie, komentarz przy źródle dla luki w nawigacji.
  • Puść /doctor prompt-audit ze ścieżką do plików, które ruszyłeś, zastosuj jego zmiany, a potem sam zrób commit tych plików.
  • Puść to samo zadanie w świeżej sesji i patrz, jak porażka się nie powtarza.

Pomiary

To małe biegi na jednym zmyślonym API do faktur (Node i TypeScript, TypeScript, vitest) z Claude Code 2.1.294. To demonstracja, nie benchmark. Ukryty test księgowy to pięć kontroli napisanych przed biegiem.

Krok Wynik
Zadanie not kredytowych, próba 1 Czysto: 40 przeszło, ukryty test księgowy 5/5 (odrzucone, to nie sesja z defektem)
Zadanie not kredytowych, próba 2 42 przeszło, typecheck exit 0, ukryty test księgowy 4/5. Wyszło CN-0004 zamiast należnego CN-0002
Pierwsze retro, bez zgłoszonej porażki 5 uszeregowanych pozycji, zaczęło się od "This session was smooth"
Śledzenie pierwszego retro 2 ocalałych, 3 odrzuconych
Drugie retro, porażka zgłoszona 5 kandydatów
Śledzenie drugiego retro 4 ocalałych, 1 odrzucony
Zatwierdzone ręcznie 4 zmiany: hook, test, linia standardów, komentarz przy źródle. Żadnej linii w CLAUDE.md
Pierwsza próba commitu Hook go zablokował: 1 nie przeszedł, 42 przeszło (43). Drzewo nadal zawierało zbugowany kod
Po poprawce w jednej linii Zestaw 43/43, ukryty test księgowy 5/5, commity przeszły
Świeża sesja B, to samo żądanie 37 przeszło, typecheck exit 0, ukryty test księgowy 5/5, numery bez dziur po odrzuconym żądaniu

Czytaj to ostrożnie:

  • Z dwóch zwykłych biegów tego zadania jeden wypuścił buga przed retro. Po retro mamy tylko jedno powtórzenie, więc to n=1.
  • Sesja B przeczytała plik standardów, hook i czerwony test numeracji, zanim napisała kod. Dostała lekcję. Jej sukces pokazuje pętlę działającą zgodnie z projektem, nie niezależną replikację.
  • Retro nigdy samo nie znalazło buga. Jego pierwszy przebieg znalazł brakujące zabezpieczenie, które, jego własnymi słowami, nie wyłapałoby tego buga.
  • Nowy hook sprawdza drzewo robocze. git cherry-pick commitu retro na bazę go nie uruchomił.
  • Bez ścieżki prompt audit przeczytał pliki na poziomie użytkownika i nic nie powiedział o nowych. Ze ścieżką pliku standardów odpowiedział, że plik jest czysty.
  • Starsza route wystawiania faktur w tym repo gubi numery w ten sam sposób. Zostawiliśmy ją, bo wykracza poza zakres tej sesji.

Czytaj dalej

Przeczytaj osobę, która naprawdę prowadzi pętlę lekcji. Jeden programista wstrzykuje na starcie sesji datowany plik z lekcjami i zamienia regułę, która ciągle się osuwa, w test, regułę lintera albo hooka, a CLAUDE.md trzyma jako krótki router. s6

Przeczytaj issue, zanim zaufasz retro. Issue 1173 to argument za krokiem śledzenia. s7 Issue 1311 to zapomniany commit. s23 Issue 1158 to brakująca komenda w oficjalnym marketplace. s24

Dowiedz się, gdzie leżą logi i jak długo. Strona o sesjach obejmuje ścieżkę transkryptu, wznawianie po ścieżce i czyszczenie po 30 dniach. s8

Auto memory to automatyczna alternatywa. Pominęliśmy ją. Tyrada jednego autora twierdzi, że zapisuje po cichu, nie jest wersjonowana i trzyma drobiazgi obok trwałych reguł, dlatego trzymamy człowieka, który zatwierdza każdą linię. s11 Traktuj to jako jedną opinię i sprawdź na własnej konfiguracji.

/insights to cotygodniowy towarzysz. Buduje raport HTML z do 200 sesji, z punktami tarcia i sugestiami. s14 Jeden raport z praktyki zamienił 64 sesje w 5 linii CLAUDE.md, 2 skille i hooki. s12 Tu go nie puszczaliśmy.

Pętla Anthropic jest ręczna. Jej wpis o harnessie opisuje strojenie przez czytanie logów ewaluatora, znajdowanie miejsc, gdzie jego osąd się rozjechał, i aktualizowanie promptu. s13 Nie znaleźliśmy oficjalnej komendy ani wpisu o retro na pierwszej stronie indeksu engineering. s27

Dlaczego tego nie zautomatyzowaliśmy. Wyzwalacz na koniec sesji byłby klejem, który sami napisaliśmy i nie przetestowaliśmy. Hooki końca sesji nie mogą zablokować zakończenia i mają domyślny timeout 1,5 sekundy, a skill retro uruchamia się tylko ręcznie. s5 s1 Docsy retro mówią, że tylko proponuje i że nic się nie zmienia, dopóki nie wybierzesz kandydata. s2 Zostawiliśmy człowieka w pętli.

Co zostawiliśmy poza zakresem. Ten sam błąd kolejności istnieje w starszej route wystawiania faktur w tym repo, a retro na niej byłoby osobnym biegiem. Nie dodaliśmy też zadania CI, bo nasza kopia nie miała zdalnego repo i workflow nigdy by nie ruszył.

FAQ

Dlaczego retro uznało moją sesję za gładką? Czyta log sesji, a sesja nigdy nie dowiedziała się, że zawiodła: jej testy i typecheck były zielone. Puść je jeszcze raz z opisem porażki wpisanym po komendzie, jako argument.

Czy retro zmienia moje pliki? Tylko proponuje. Nic się nie zmienia, dopóki nie wybierzesz kandydata. s2 Po zatwierdzeniu zmiany mogą zostać wdrożone, ale nie zacommitowane, więc commit robisz sam. s23

Czy mogę puścić je na sesji, którą już wyczyściłem? Tak, jeśli log nadal jest na dysku. Transkrypty leżą w ~/.claude/projects/ i domyślnie są czyszczone po 30 dniach, a claude --resume <transcript-path> otwiera jeden z nich. s8

Dlaczego mój nowy hook zablokował commit? Puszcza twój typecheck i testy na drzewie roboczym. Jeśli drzewo nadal zawiera buga, który test teraz łapie, commit zostaje odrzucony. Najpierw popraw kod, potem zrób commit.

Dlaczego nie ma linii w CLAUDE.md? Oba nasze przebiegi retro jej odmówiły, mówiąc, że wskaźnik kosztowałby kontekst w każdej turze i się zestarzał. Docsy celują w mniej niż 200 linii i mówią, że CLAUDE.md to kontekst, nie wymuszona konfiguracja. s4

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