Implements ADR-4 (CLAUDE.md section 3, `rusqlite` bundled). Schedules, lock
state, disable attempts and usage buckets now persist across restarts.
**Why a new crate rather than a module inside `blocker-core`.** The purity
contract says the engine does no I/O, and `tests/purity.rs` enforces that
mechanically by failing if `blocker-core` has any dependency at all. Putting
rusqlite in `blocker-core` would have forced that check to degrade into a
source-text grep — something a careful developer can route around and nobody
reads in six months. `blocker-storage` depends on `blocker-core`; the reverse
edge does not exist, so the zero-dependency proof stays automatic.
Both crates sit in the same layer of the section 2 diagram: storage is shared by
every platform and contains no platform code.
**Schema is relational, not JSON-in-a-text-column.** `schedule_target` and
`schedule_condition` are separate tables because target rows are queried by
target, and an index on a JSON string is not a plan. Serialisation is
hand-written in `storage/src/codec.rs` — `serde` is not a section 3 dependency,
and section 0 rule 3 requires asking before adding one.
**Fail open, verified end to end** (section 1.5.4). Corruption moves the damaged
file aside and starts clean, keeping the original for diagnosis. Confirmed
against the real binary, not only in tests:
```
$ printf 'SQLite format 3\x00 not a database' > .../blocker.db
$ blocker-daemon
blocker-daemon: database was corrupt and has been moved to
.../blocker.db.corrupt; starting clean, so no schedules are active
until you re-add them
EXIT=0
```
A truncated file is covered separately — that is what a power loss during a
write actually produces, and it fails differently from garbage bytes.
**Two bugs this PR's own tests caught:**
1. `prune_usage` anchored its cutoff on `MIN(day_index)`, the oldest row. Since
that row is by definition the one being tested, the cutoff always sat before
it and the delete matched nothing — the table grew forever, which is the slow
disk leak the function exists to prevent. Now anchored on `MAX`.
2. An off-by-one in the same function: with a strict `<` against
`newest - keep_days`, the boundary day was kept too, yielding `keep_days + 1`
rows. Both are covered by `old_usage_is_pruned`.
**Cost, measured rather than assumed:** the stripped daemon goes from 0.279 MB
to **1.364 MB** with SQLite actually linked in — bundled SQLite is ~1.1 MB of
the 5 MB budget, leaving 3.8 MB for D-Bus, X11 and a UI toolkit. That is a real
margin rather than a comfortable one, and it makes ADR-4's bundled-vs-system
trade-off a genuine open question rather than a settled one.
The M0 figure of 0.279 MB excluded SQLite entirely, because dead-code elimination
dropped a crate the placeholder binary never referenced.
Co-Authored-By: Claude Code <noreply@anthropic.com>
Establishes the cargo workspace and the shared `blocker-core` crate. The
engine is deliberately written before any platform code, because CLAUDE.md
section 2 makes it the single source of decision truth and M1 acceptance
requires it to be pure.
**Workspace** — five crates plus a test crate, zero external dependencies.
Section 3 requires every crate to justify its binary-size cost, so M0 adds
none. [profile.release] is workspace-only (cargo rejects it in members) and
carries the section 5 settings that make the 5 MB stripped budget reachable.
**Purity contract** — `evaluate(&EngineInput) -> Decision` reads no clock, no
disk and no OS API; everything arrives in the input. `tests/purity.rs`
enforces this mechanically by asserting blocker-core has zero dependencies, so
a stray I/O reach-in fails the build rather than silently making the golden
tables useless as a parity contract.
Decisions worth calling out:
- **Monotonic time is a separate type from wall time.** Section 1.5.3 requires
a system date change never to shorten a lock. Keeping them apart makes that
structural rather than a rule to remember.
- **`start > end` means overnight.** No `crosses_midnight` flag: the comparison
already encodes it and a second field is a second way to be wrong. The
weekday for a window that started yesterday evening is yesterday's, which
`overnight_window_survives_past_midnight` pins down.
- **`next_wakeup` is armed over every non-paused schedule, not only active
ones.** Filtering to active conditions first would let the daemon sleep
straight through the moment a schedule is due to start.
- **Allowlist needs the installed-app inventory.** `EngineInput` carries
`installed_apps`; an empty slice fails open rather than guessing.
- **Wall-clock correction extends, never shortens, and clamps to the 24h cap.**
Extending unbounded would satisfy anti-tamper and violate section 1.5.4.
- **`cast_possible_truncation` is denied workspace-wide.** Truncating a
millisecond counter would corrupt a lock timer.
Verified: 22 tests pass, `cargo fmt --check` clean, `cargo clippy -D warnings`
clean, stripped release daemon 0.279 MB against the 5 MB budget.
Co-Authored-By: Claude Code <noreply@anthropic.com>
SellPL