# M5a task 07: the journal, undo and review

**Branch:** `m5a` (run `git switch m5a`; `git status --short` must be empty, otherwise stop)
**Commit subject:** `memoryd: the edit journal, undo of the latest edit, and review`

## Goal

M5a spec, section 5, "Seeing writes", "Undo" and "Review":

- Every applied write is one JSON line in `memory/edits/YYYY-MM.jsonl`, with an id numbered from 1
  each day (`2026-09-24-0001`), the entries before and after, and where it went. `log` lists the
  last N.
- `undo` reverts an edit only if it is the latest edit of its identity file **and** the file still
  holds exactly what it left; the undo is journalled too. Notes are append-only and never undone.
- With review on, identity writes wait in `memory/pending.jsonl` until the owner accepts one
  (applied then, against the file as it is) or rejects it (journalled).

## Files

- Copy (skeletons): `crates/memoryd/src/journal.rs`, `crates/memoryd/src/review.rs`
- Copy (test): `crates/memoryd/tests/journal.rs`
- Modify: `crates/memoryd/src/lib.rs` (`pub mod journal;` after `pub mod files;`,
  `pub mod review;` after `pub mod notes;`), `docs/implementer-log.md`

## The skeletons

`journal.rs`: `Record` and `file_of` are written; fill `records`, `append`, `record`, `log`,
`undo`. `append` is `pub(crate)` because `review::reject` journals through it. `review.rs`:
`Line` is written; fill `lines`, `add`, `waiting`, `submit`, `list`, `accept`, `reject`.

## Steps

- [ ] **1. Copy** the three files; edit `lib.rs`.
- [ ] **2. See it fail.** `cargo test -p memoryd --test journal`: 4 failed.
- [ ] **3. Fill** `journal.rs`, then `review.rs`. `cargo fmt --all`.
- [ ] **4. See it pass.** The same command: 4 passed.
- [ ] **5. Run the gate.** `make gate`: `gate: ok`, 4 more tests than before (about 900).
- [ ] **6. Log and commit.** `git add -A crates/memoryd docs/implementer-log.md Cargo.lock && git commit`

## Done when

- `make gate` prints `gate: ok`.

## Stop and report if

- A test fails after the functions follow their comments exactly. Do not edit a test.