loopd: heartbeat tick on the background slot

Co-Authored-By: ornith-1.5-35b-a3b <agent@wntrmute.dev>

docs/implementer-log.md

@@ -6,6 +6,7 @@ reviewer adds findings under "Reviews" once per milestone.
 
 | Task | Date | Status | Gate runs | First gate | Deviations | Notes | Model |
 |---|---|---|---|---|---|---|---|
+| M5d2/06-loopd-scheduler-heartbeat | 2026-10-03 | done | 2 | fail | none | Copied the given test `crates/loopd/tests/scheduler_heartbeat.rs` from `docs/plans/M5d2/files/`. Made `crates/loopd/src/scheduler.rs` from the skeleton: `tick` closes idle leftovers once on the first tick, then runs `heartbeat`; `heartbeat` returns early when `every_s == 0` or when not due (`now - last_heartbeat.unwrap_or(started) >= every_s * 1000`), reads the prompt first (pushing `HeartbeatUnreadable` and logging once via `heartbeat_unreadable_logged` on a failed read, without holding), then holds `heartbeat` (pushing `SkippedBusy` on `Busy`), opens it or creates it on `NotFound` with `Baseline::assemble` and the background slot, and runs the turn with `speaker None` and a no-op emit, updating `last_heartbeat` and pushing `Heartbeat` only on an ok outcome. `close_idle_leftovers` loads the jobs and, for each with a live `Started` session, holds it -- dropping the hold and appending a `Failed` run when the hold succeeds and skipping when it is `Busy`, rather than calling `jobs::close_leftovers` blindly, so a busy session is never closed. Added `pub mod scheduler;` after `pub mod llama;` in `lib.rs`. Wired `run_serve` to spawn a thread that `tick`s once a second before `channel::serve`. Made `Held` pub, added `pub struct Busy` and `Context::hold` in `channel.rs`. Appended the given `heartbeat-prompt-unreadable` entry to `docs/runbook.md` (heading count 1). First `make gate` failed on clippy `single_match` in `close_idle_leftovers`, fixed by converting the match to `if let Ok(held)` (the `Busy` case is the skip); the second run printed `gate: ok` with 1551 tests (1545 before, plus the 6 of `scheduler_heartbeat.rs`). No new dependency, so `Cargo.lock` unchanged. | ornith-1.5-35b-a3b |
 | M5d2/05-loopd-jobs | 2026-10-03 | done | 2 | fail | none | Copied the given test `crates/loopd/tests/jobs.rs` from `docs/plans/M5d2/files/`. Made `crates/loopd/src/jobs.rs` from the skeleton (192 lines, under 500): `session_id` builds `job-<name>-<yyyymmdd>t<hhmm>` from `to_rfc3339()` and maps a `SessionId::new` failure to `JobsError::Name`; `load` reads the dir (NotFound -> empty, any other IO error or an unreadable file -> Invalid naming the path), skips names not ending in `.toml`, validates the stem against `[a-z0-9-]+` on the bytes (empty or bad -> Name), parses each with a private `File { schedule, prompt }` and `deny_unknown_fields`; `append` creates the parent dir, opens in append mode, writes one JSON object plus a newline and `sync_all`; `live_session` walks every line of the ledger (missing file -> None) and returns the last matching run's session only when that run is `Started`; `close_leftovers` closes each name whose last run is `Started` with a `Failed` run carrying the same session and `now`, and returns the count (missing file -> 0). Added `pub mod jobs;` after `pub mod llama;` in `lib.rs` (rustfmt order). Wired `run_serve` to call `jobs::load(&cfg.paths.home.join("jobs"))` after `check_summarise`, printing `loopd: {e}` and exiting 1 on error, without creating the directory. Appended the given `jobs-invalid` entry to `docs/runbook.md` (heading count 1). `cargo check -p loopd` clean, no error or warning; all 8 `jobs` tests pass. First `make gate` failed on clippy `collapsible-if` in `append` (the parent-dir guard), which I fixed by combining the two guards into one `if let Some(parent) = path.parent() && !parent.as_os_str().is_empty()`; the second run printed `gate: ok` with 1545 tests (1537 before, plus the 8 of `jobs.rs`). No new dependency, so `Cargo.lock` unchanged. | ornith-1.5-35b-a3b |
 | M5d2/04-loopd-cron | 2026-10-03 | done | 2 | pass | none | Copied the given test `crates/loopd/tests/cron.rs` from `docs/plans/M5d2/files/`. Step 2 (`cargo build --tests --keep-going -p loopd`) showed exactly the named failure: `cron` with E0432 (`unresolved import loopd::cron`); every other target compiled. Made the module `cron.rs` from the skeleton: `due` splits on whitespace, requires five pieces, reads the civil fields from `to_rfc3339`, computes DOW as `(unix_millis/1000/86400 + 4) % 7`, ANDs the five `match_field` checks; `match_field` handles `*`, `*/n` (with `n == 0` rejected via `is_multiple_of`), `n-m` ranges, and bare numbers, each range-checked against the field bounds. Added `pub mod cron;` after `pub mod config;` in `lib.rs` (rustfmt order). `cargo check -p loopd` clean, no error or warning. `cargo test -p loopd --test cron` passes all 11. `wc -l crates/loopd/src/cron.rs` prints 150, well under 500. `git diff --stat` lists only `cron.rs` and `lib.rs`; `git status --short` shows `cron.rs` and the test as untracked. `cargo fmt --all` changed nothing after the edits. `make gate` printed `gate: ok` with 1537 tests (1526 before, plus the 11 of `cron.rs`), matching the task's expected count. No new dependency, so `Cargo.lock` unchanged. | ornith-1.5-35b-a3b |
 | M5d2/03-loopd-heartbeat-config | 2026-10-03 | done | 1 | pass | none | Copied the given test `crates/loopd/tests/config_heartbeat.rs` and the starter `config/heartbeat.md` from `docs/plans/M5d2/files/`. Step 2 (`cargo build --tests --keep-going -p loopd`) showed exactly the named failure: `config_heartbeat` with E0609 (`no field heartbeat`) and E0599 (`no method heartbeat_prompt` / `check_summarise`); every other target compiled. Made H1 (`Config` gains `#[serde(default)] pub heartbeat: Heartbeat` after `compact`), H2 (new `Heartbeat { every_s: u64, prompt: PathBuf }` with `#[serde(deny_unknown_fields, default)]`, `Default` = `every_s` 0 and `prompt` `heartbeat.md`, placed after `Compact`'s Default impl), H3 (`load` joins `heartbeat.prompt` to the config file's parent beside `baseline.system`), H4 (`heartbeat_prompt` returns `self.heartbeat.prompt.clone()`, `check_summarise` walks `summarise` and returns Err naming both `summarise` and the unknown name, both after `compact_prompt`). Made M1 (`run_selftest`) and M2 (`run_serve`): after a successful `load` each calls `cfg.check_summarise(&loopd::tools::Registry::m5c())`, printing `loopd: {e}` and returning exit 1 on failure, before `Client::new` / the instance lock. Made A1 (`ask_memory_tool.rs` `loopd_serve_uses_the_m5c_registry` counts `Registry::m5c()` as 3). `cargo check -p loopd` clean, no error or warning. `cargo test -p loopd --test config_heartbeat --test config --test config_compact --test ask_memory_tool` passes (8 + 11 + 8 + 4). `git diff --stat` lists only `config.rs`, `main.rs` and `ask_memory_tool.rs`; `git status --short` shows the new test and `heartbeat.md` as untracked. `cargo fmt --all` changed nothing after the edits. `make gate` printed `gate: ok` with 1526 tests (1518 before, plus the 8 of `config_heartbeat.rs`), matching the task's expected count. No new dependency, so `Cargo.lock` unchanged. | ornith-1.5-35b-a3b |

docs/runbook.md

@@ -1217,3 +1217,29 @@ ls -l "$BOXMAKER_HOME/jobs/"
 Then start `loopd` again.
 
 **Check.** `loopd serve` prints `serving on` and `{home}/jobs/runs.jsonl` exists (empty is fine).
+
+## heartbeat-prompt-unreadable
+
+**What you see.** `loopd` is serving, but heartbeat turns do not run. It logs this line once,
+until the file reads:
+
+```text
+loopd: heartbeat.md: Permission denied (os error 13); see docs/runbook.md#heartbeat-prompt-unreadable
+```
+
+**Why.** `[heartbeat] prompt` is next to the config file (default `heartbeat.md`). The scheduler
+skips the tick rather than send an empty or guessed user message. A missing file is the same:
+restore the starter from `config/heartbeat.md` in the repository.
+
+**Confirm.**
+
+```sh
+ls -l "$(dirname "$LOOPD_CONFIG")/heartbeat.md"
+```
+
+**Fix.** Restore mode `0644` (or whatever the owner uses for the other prompts) and content.
+The next tick after a successful read logs nothing extra and runs the standing `heartbeat`
+session.
+
+**Check.** `sessions/heartbeat/0.jsonl` gains a new `User` whose text starts with `It is ` and an
+RFC 3339 timestamp.