boxmaker/docs/plans/M5d2/11-loopd-heartbeat-failed-last.md

# M5d-2 task 11: a failed heartbeat still advances `last_heartbeat`

**Branch:** `m5d2`. Check it: `git branch --show-current` prints `m5d2` and `git status --short`
is empty; otherwise stop. Never switch branch.
**Commit subject:** `loopd: a failed heartbeat still advances last_heartbeat`
**Log row:** the Task cell is `M5d2/11-loopd-heartbeat-failed-last`.

**First action.** Run this before any Read of crate source. Do not `ls` `crates/loopd/tests/`.
Do not Read `tests/support/`, `session.rs`, `turn.rs`, `compact.rs`, `jobs.rs`, or
`docs/implementer-log.md` (except the first 12 lines at the log step). The quoted block is
the only edit.

```sh
cp docs/plans/M5d2/files/crates/loopd/tests/scheduler_heartbeat_failed.rs crates/loopd/tests/
```

## Goal

After `run_turn` and `finish_turn` on the standing `heartbeat` session, always set
`last_heartbeat = Some(now)` and push `TickWork::Heartbeat`, including when the outcome is
`Err` (M5d-2 review finding 1; task 06's "The turn" fact). A failed pulse must not be due
again on the next 1 s tick.

An unreadable prompt still does not update `last_heartbeat`. A busy skip still does not.
Cron `Finished` / `Failed` is unchanged.

## Every place that changes

| Place | What happens there |
|---|---|
| `crates/loopd/src/scheduler.rs` | after the heartbeat turn, bookkeeping is unconditional (edit H1) |
| `crates/loopd/tests/scheduler_heartbeat_failed.rs` | new, given |
| everything else | **no change** |

## Files

- Copy, from `docs/plans/M5d2/files/` (the same path under it): the new test
  `crates/loopd/tests/scheduler_heartbeat_failed.rs`.
- Modify: `crates/loopd/src/scheduler.rs`, `docs/implementer-log.md`.
- Do not touch: any other file. Do not edit `crates/loopd/tests/scheduler_heartbeat.rs`.

## Facts you need

- **H1.** In `heartbeat`, the quoted block is found exactly once. Replace it with the after
  block. `finish_turn` still runs. `drop(held)` still runs. Then `last_heartbeat` and
  `Heartbeat`, with no `if outcome.is_ok()`.
- **Unreadable prompt / Busy.** Those `return` paths stay as they are. They never reach H1.
- **`Reply::fixture("bad_request")`** is HTTP 400. It is not retried. The given test does
  not sleep (T27).

## The edit (H1)

In `crates/loopd/src/scheduler.rs`, this block (exactly once):

```rust
        let text = format!("It is {}.\n\n{file}", now.to_rfc3339());
        let mut emit = |_event: &TurnEvent| {};
        let outcome = run_turn(&mut session, &runtime, &text, None, &mut emit);
        let outcome = compact::finish_turn(
            &mut session,
            &runtime,
            &*ctx.memory,
            &text,
            None,
            &mut emit,
            outcome,
        );
        if outcome.is_ok() {
            self.last_heartbeat = Some(now);
            work.push(TickWork::Heartbeat);
        }
        drop(held);
```

becomes:

```rust
        let text = format!("It is {}.\n\n{file}", now.to_rfc3339());
        let mut emit = |_event: &TurnEvent| {};
        let outcome = run_turn(&mut session, &runtime, &text, None, &mut emit);
        let _ = compact::finish_turn(
            &mut session,
            &runtime,
            &*ctx.memory,
            &text,
            None,
            &mut emit,
            outcome,
        );
        drop(held);
        self.last_heartbeat = Some(now);
        work.push(TickWork::Heartbeat);
```

## Steps

- [ ] **1. Copy the given test.**

  ```sh
  cp docs/plans/M5d2/files/crates/loopd/tests/scheduler_heartbeat_failed.rs crates/loopd/tests/
  ```

- [ ] **2. See it fail.** `cargo test -p loopd --test scheduler_heartbeat_failed`, timeout
  600000 ms. Expected: one test fails,
  `a_failed_heartbeat_turn_still_advances_last_heartbeat`, with `left: []` and
  `right: [Heartbeat]`. Every other loopd test target is untouched. Do not open the test
  to find out why.
- [ ] **3. Make H1.** The before block is found exactly once. `cargo fmt --all`.
  `cargo check -p loopd` prints no error and no warning.
- [ ] **4. See it pass.** `cargo test -p loopd --test scheduler_heartbeat_failed --test
  scheduler_heartbeat`: every test passes, 1 in `scheduler_heartbeat_failed`, 6 in
  `scheduler_heartbeat`.
- [ ] **5. Run the gate.** `cargo fmt --all`, then `make gate`, timeout 600000 ms. Last line
  `gate: ok`. Test count **1575** (1574 before, plus 1). After `gate: ok`, do not add up
  `test result:` lines.
- [ ] **6. Log and commit.** Task cell `M5d2/11-loopd-heartbeat-failed-last`. Read only the
  first 12 lines of `docs/implementer-log.md`; insert the row under the header. Stage with
  `git add crates/loopd/src/scheduler.rs crates/loopd/tests/scheduler_heartbeat_failed.rs
  docs/implementer-log.md Cargo.lock`, then commit as `AGENTS.md` says.

## Done when

- `make gate` prints `gate: ok` with 1575 tests.
- `git diff HEAD~1 --stat` lists only `crates/loopd/src/scheduler.rs`,
  `crates/loopd/tests/scheduler_heartbeat_failed.rs` and the log.

## Stop and report if

- The branch check fails; the before block is not found exactly once; step 2 differs (a
  different test fails, or it passes); `cargo check` warns; a test in
  `scheduler_heartbeat` fails; the gate's last line is not `gate: ok`; you edit the
  unreadable-prompt path; you change cron `Finished` / `Failed`.

## What the given tests pin

A due heartbeat whose inference returns HTTP 400 still pushes `Heartbeat` and is not due
again 30 s later (`every_s` 60). The existing six heartbeat tests stay green: `every_s` 0,
busy skip, unreadable prompt, and a successful second tick before `every_s`.