# M4b task 01: move the text escaping into `proto`

**Branch:** `m4b` (run `git switch m4b`; `git status --short` must be empty, otherwise stop)
**Commit subject:** `proto: escape, moved from bxctl so gatewayd shows the same thing`

## Goal

`bxctl` escapes text it did not write (model output, tool arguments, server errors) before it
reaches the terminal: control characters, zero-width and bidirectional marks, line separators and
the BOM become `\uXXXX`. M4b posts tool arguments in Mattermost, and they must be escaped by the
same rules, so the code moves to `proto`, where both can use it. **Nothing changes in what it
does.** `bxctl::escape` stays, as a re-export, so no `bxctl` code or test changes.

## Files

- Copy: `crates/proto/src/escape.rs` (complete), `crates/bxctl/src/escape.rs` (complete, replaces
  the old one), `crates/proto/tests/escape.rs`
- Modify: `crates/proto/src/lib.rs` (`pub mod escape;`, after `pub mod class;`),
  `docs/implementer-log.md`

`proto/src/escape.rs` is `bxctl`'s old file with a new module comment. `bxctl/src/escape.rs` becomes
one line: `pub use proto::escape::{escape_json_text, escape_model_text};`. The new test is
`bxctl`'s escape test, pointed at `proto::escape`.

## Steps

- [ ] **1. Copy.** `git switch m4b`, then
  `cp docs/plans/M4b/files/crates/proto/src/escape.rs crates/proto/src/ && cp docs/plans/M4b/files/crates/bxctl/src/escape.rs crates/bxctl/src/ && cp docs/plans/M4b/files/crates/proto/tests/escape.rs crates/proto/tests/`.
  Add `pub mod escape;` to `crates/proto/src/lib.rs`.
- [ ] **2. See it pass.** `cargo test -p proto --test escape` (8 passed) and `cargo test -p bxctl`
  (every suite passes, unchanged).
- [ ] **3. Run the gate.** `cargo fmt --all`, then `make gate`. Expected last line: `gate: ok`.
- [ ] **4. Log and commit.**
  `git add crates/proto crates/bxctl docs/implementer-log.md Cargo.lock && git commit`

## Done when

- Both crates' tests pass; `make gate` prints `gate: ok`.

## Stop and report if

- Any `bxctl` test changes result: the move must not change behaviour.