boxmaker/docs/plans/M5a/18-repeated-code.md

# M5a task 18: the same few lines written once, not four times

**Branch:** `m5a` (run `git switch m5a`; `git status --short` must be empty, otherwise stop)
**Commit subject:** `memoryd, proto, brokerd, bxctl: repeated error lines written once`

## Goal

No behaviour change. In four places the same lines are written out again and again. Each one
becomes a small helper, so a later change to a sentence or a check is made once. Found in the M5a
review (2026-09-24).

| File | Repeated | Becomes |
|---|---|---|
| `crates/memoryd/src/edit.rs` | the stale and "named twice" check, 4 times in `consolidate` | a function `claim` |
| `crates/proto/src/memory.rs` | `if let Some(problem) = entry_problem(..) { return Err(problem); }`, 9 times in `MemoryArgs::check` | a function `entry` |
| `crates/brokerd/src/builtin.rs` | the `GrantProblem`, twice in `grants` | a closure `problem` |
| `crates/bxctl/src/memory.rs` | `cannot reach memoryd at …`, 4 times in `run` | a closure `unreachable` |

## Files

- Modify: the four files in the table, `docs/implementer-log.md`
- No test changes: the existing tests cover every line changed.

## The edits, exactly

Nothing else in these files changes. Leave the comments that are there as they are.

### 1. `crates/memoryd/src/edit.rs`

**a.** Insert this function immediately above the line `fn consolidate(`, with one blank line
between them:

```rust
/// Mark the entry `old` names as named: stale if `before` has no such entry, an error if it was
/// named already.
fn claim(
    file: MemoryFile,
    before: &[String],
    named: &mut HashSet<usize>,
    old: &str,
) -> Result<(), String> {
    let pos = position(before, old).ok_or_else(|| stale(file))?;
    if named.insert(pos) {
        Ok(())
    } else {
        Err(format!(
            "consolidate names an entry of {} twice",
            file.name()
        ))
    }
}
```

**b.** In `consolidate`, this block appears four times, in the `Keep`, `Rewrite`, `Move` and
`Drop` arms:

```rust
                let pos = position(before, &old).ok_or_else(|| stale(file))?;
                if !named.insert(pos) {
                    return Err(format!(
                        "consolidate names an entry of {} twice",
                        file.name()
                    ));
                }
```

Replace each of the four with the one line

```rust
                claim(file, before, &mut named, &old)?;
```

The line after it in each arm (`after.push(..)` or `out.push(..)`) stays. The `New` arm does not
have the block and does not change.

### 2. `crates/proto/src/memory.rs`

**a.** Insert this function immediately above the line `impl RecallArgs {`, with one blank line
between them:

```rust
/// `entry_problem` as a `Result`, so a check can use `?`.
fn entry(text: &str, max: usize) -> Result<(), String> {
    match entry_problem(text, max) {
        Some(problem) => Err(problem),
        None => Ok(()),
    }
}
```

**b.** In `impl MemoryArgs`, replace the whole function `pub fn check(&self) -> Result<(), String>`
(from that line to its closing `}`, the `Ok(())` at its end included) with the following. Keep
the doc comment above it.

```rust
    pub fn check(&self) -> Result<(), String> {
        match self {
            MemoryArgs::Add { text, .. } => entry(text, MAX_ENTRY),
            MemoryArgs::Replace { old, text, .. } => {
                entry(old, MAX_ENTRY)?;
                entry(text, MAX_ENTRY)
            }
            MemoryArgs::Remove { old, .. } => entry(old, MAX_ENTRY),
            MemoryArgs::Note { text } => entry(text, MAX_NOTE),
            MemoryArgs::Consolidate { entries, .. } => {
                if entries.is_empty() {
                    return Err("consolidate needs every entry of the file".to_string());
                }
                for line in entries {
                    match line.action().map_err(str::to_string)? {
                        EntryAction::Keep(old)
                        | EntryAction::Move(old)
                        | EntryAction::Drop(old) => entry(&old, MAX_ENTRY)?,
                        EntryAction::Rewrite { old, text } => {
                            entry(&old, MAX_ENTRY)?;
                            entry(&text, MAX_ENTRY)?;
                        }
                        EntryAction::New(text) => entry(&text, MAX_ENTRY)?,
                    }
                }
                Ok(())
            }
        }
    }
```

`RecallArgs::check` does not change.

### 3. `crates/brokerd/src/builtin.rs`

In `grants`, inside the `for` loop, the lines

```rust
        let grant = toml::from_str::<Grant>(text).map_err(|error| GrantProblem {
            file: id.to_string(),
            line: None,
            problem: error.to_string(),
        })?;
        let sha256 = sha256(text.as_bytes()).map_err(|error| GrantProblem {
            file: id.to_string(),
            line: None,
            problem: error.to_string(),
        })?;
```

become

```rust
        let problem = |error: String| GrantProblem {
            file: id.to_string(),
            line: None,
            problem: error,
        };
        let grant = toml::from_str::<Grant>(text).map_err(|e| problem(e.to_string()))?;
        let sha256 = sha256(text.as_bytes()).map_err(|e| problem(e.to_string()))?;
```

### 4. `crates/bxctl/src/memory.rs`

**a.** In `run`, the first lines of the body

```rust
    let mut stream = UnixStream::connect(socket)
        .map_err(|e| format!("cannot reach memoryd at {}: {e}", socket.display()))?;
    stream
        .set_read_timeout(Some(timeout))
        .map_err(|e| format!("cannot reach memoryd at {}: {e}", socket.display()))?;
    stream
        .set_write_timeout(Some(timeout))
        .map_err(|e| format!("cannot reach memoryd at {}: {e}", socket.display()))?;
```

become

```rust
    let unreachable =
        |e: &dyn std::fmt::Display| format!("cannot reach memoryd at {}: {e}", socket.display());
    let mut stream = UnixStream::connect(socket).map_err(|e| unreachable(&e))?;
    stream
        .set_read_timeout(Some(timeout))
        .map_err(|e| unreachable(&e))?;
    stream
        .set_write_timeout(Some(timeout))
        .map_err(|e| unreachable(&e))?;
```

**b.** Further down in `run`, the lines

```rust
    write_frame(&mut stream, &env)
        .map_err(|e| format!("cannot reach memoryd at {}: {e}", socket.display()))?;
```

become

```rust
    write_frame(&mut stream, &env).map_err(|e| unreachable(&e))?;
```

The `memoryd did not answer` line after it does not change: it is a different sentence.

## Steps

- [ ] **1. Make the edits**, one file at a time, running `cargo check -p <crate>` after each
  (`memoryd`, `proto`, `brokerd`, `bxctl`). Then run `cargo fmt --all`.
- [ ] **2. Check the repeats are gone.** Each of these prints the number shown:
  - `grep -c 'named.insert' crates/memoryd/src/edit.rs` prints `1`
  - `grep -c 'if let Some(problem) = entry_problem' crates/proto/src/memory.rs` prints `0`
  - `grep -c 'GrantProblem {' crates/brokerd/src/builtin.rs` prints `2` (the closure, and the
    comment above the loop)
  - `grep -c 'cannot reach memoryd' crates/bxctl/src/memory.rs` prints `1`
- [ ] **3. Run the tests.** `cargo test -p memoryd -p proto -p brokerd -p bxctl`: every suite
  passes.
- [ ] **4. Run the gate.** `make gate`. Expected last line: `gate: ok`, with 936 tests, the same
  as before this task.
- [ ] **5. Log and commit.**
  `git add crates/memoryd crates/proto crates/brokerd crates/bxctl docs/implementer-log.md && git commit`

## Done when

- `make gate` prints `gate: ok`, and step 2's four counts are as shown.

## Stop and report if

- Any block quoted above is not in the file exactly as shown, or appears a different number of
  times than the task says.
- Any test fails. This task changes no behaviour, so a failure means an edit is wrong; do not
  change a test.