docs: record the measured storage cost and the new crate boundary

Updates the ADR log, architecture, limitations, perf table and README to match
what now exists, rather than what was expected.

**The perf number was wrong and is now honest.** The M0 figure of 0.279 MB
excluded SQLite entirely — the placeholder binary never referenced the crate, so
dead-code elimination dropped it. With the daemon actually opening a database it
is **1.364 MB**, of which bundled SQLite is ~1.1 MB. That is 1.1 MB of the 5 MB
budget spoken for, leaving 3.8 MB for D-Bus, X11 and a UI toolkit.

This is the first number that makes the section 5 budget feel like a budget
rather than a formality, and it turns ADR-4's bundled-vs-system-linked choice
into a real trade-off with a measured price on both sides.

- ADR-4 marked accepted and implemented, with that trade-off left open.
- ARCHITECTURE.md documents why `blocker-storage` is a sibling crate and not a
  submodule: the dependency direction is what keeps the zero-dependency purity
  proof automatic rather than a grep someone can route around.
- LIMITATIONS.md drops the stale "storage has no I/O" shortfall and records the
  bundled-vs-system question instead, plus the fact that `LockState` still always
  evaluates to Normal.
- README status table and layout updated.

Co-Authored-By: Claude Code <noreply@anthropic.com>

README.md

@@ -16,7 +16,7 @@ enforces anything yet. No platform has a working build.
 | Milestone | State |
 |---|---|
 | M0 repo bootstrap | in progress |
-| M1 core engine | engine, lock timers and safety guarantees written and tested; storage has no I/O yet |
+| M1 core engine | engine, lock timers and safety guarantees written and tested; SQLite persistence landed in `storage/` |
 | M2-Linux | not started — daemon is a placeholder |
 | M3-Android | not started |
 | M4 conditions | not started |
@@ -74,6 +74,7 @@ summary as not-passes. A skip is never reported as a pass.
 
 ```
 core/                 the decision engine — pure, no OS calls, no dependencies
+storage/              SQLite persistence (rusqlite, bundled), fail-open recovery
 tests/                golden decision tables, and the engine purity check
 desktop/daemon/       long-lived observer and enforcer (5 MB budget)
 desktop/ui/           block-screen window, launched on demand
@@ -106,9 +107,10 @@ scripts/              ci.sh, size-check.sh
 | Daemon binary | ≤ 5 MB stripped |
 | APK size | ≤ 10 MB |
 
-Currently measured: **0.279 MB** stripped daemon — a placeholder that prints two
+Currently measured: **1.364 MB** stripped daemon, which includes bundled SQLite.
-lines. The meaningful number comes in M2-Linux. Enforced in CI from the first
+Of the 5 MB budget that leaves 3.8 MB for D-Bus, X11 and a UI toolkit — a real
-commit by `scripts/size-check.sh`.
+margin rather than a comfortable one. Enforced in CI from the first commit by
+`scripts/size-check.sh`.
 
 ## Licence
 

docs/ARCHITECTURE.md

@@ -182,10 +182,17 @@ APK size cost is unacceptable, which is a measurement before it is a decision.
 | `usage` | foreground-time and launch-count accumulation into daily and hourly buckets |
 | `lock` | lock levels, the friction ladder's timing, monotonic anti-tamper |
 | `never_block` | the section 1.5.4 safety list |
-| `storage` | the SQLite schema and its fail-open recovery policy |
+| `storage` | *(separate crate: `blocker-storage`)* the SQLite schema and its fail-open recovery policy |
 
-`storage` has no I/O behind it yet — see `LIMITATIONS.md`. The schema is written
+`blocker-storage` is a sibling crate, not a submodule. It depends on
-and reviewed as text so it can be reviewed before it is compiled.
+`blocker-core`; `blocker-core` does not depend on it, and depends on nothing at
+all. That direction is what lets `tests/purity.rs` keep checking "blocker-core has
+zero dependencies" — an automatic proof that the engine cannot do I/O — instead of
+the weaker and easily-routed-around alternative of grepping the source for
+`rusqlite`.
+
+Both crates occupy the same layer of the diagram above: storage is shared by every
+platform and contains no platform code.
 
 ## Where the platform crates start and stop
 

docs/DECISIONS.md

@@ -25,7 +25,7 @@ which parts to trust.
 | [1](#adr-1) | Rust for core and desktop, Kotlin for the Android shell | Accepted |
 | [2](#adr-2) | One shared core; the engine is a pure function | Accepted |
 | [3](#adr-3) | Event-driven with `next_wakeup`, never polling | Accepted |
-| [4](#adr-4) | SQLite via rusqlite, bundled | Proposed |
+| [4](#adr-4) | SQLite via rusqlite, in its own crate | Accepted, one trade-off open |
 | [5](#adr-5) | uniffi for core-to-Kotlin bindings | Proposed |
 | [6](#adr-6) | Desktop UI toolkit — Slint vs egui | **Proposed, needs owner** |
 | [7](#adr-7) | Desktop website blocking mechanism | **Accepted — owner chose extension** |
@@ -108,24 +108,46 @@ it is supposed to start blocking.
 ---
 
 <a id="adr-4"></a>
-## ADR-4: SQLite via rusqlite, bundled
+## ADR-4: SQLite via rusqlite
 
-**Status:** Proposed — dependency not yet added
+**Status:** Accepted and implemented, with one trade-off still open
 
 **Context.** Section 3 specifies `rusqlite` with bundled SQLite. Section 1.5.3
 requires lock and Strict state to live in the core database rather than in
 editable plaintext config.
 
-**Decision.** `rusqlite` with `bundled`, storing schedules, lock state, and usage
+**Decision.** `rusqlite` with `bundled`, in a **separate `blocker-storage` crate**
-counters in one file.
+that depends on `blocker-core`, never the reverse.
 
-**Consequences.** The schema is written and reviewed in
+**Why the separate crate.** The purity contract says the engine does no I/O, and
-`core/src/storage.rs` before the crate is added, so it can be reviewed as text.
+`tests/purity.rs` enforces that mechanically by failing if `blocker-core` has any
-Bundling compiles SQLite from source, which costs build time and binary size but
+dependency at all. Putting `rusqlite` in `blocker-core` would have forced that
-removes a system dependency — a real consideration on the machines this ships to.
+check to degrade into a source-text grep — something a careful developer can route
+around, and something nobody reads in six months. Splitting keeps the check
+automatic.
 
-The binary-size cost has not yet been measured against the 5 MB budget. That is
+Both crates sit in the same layer of the section 2 diagram: storage is shared by
-an open item, not a settled fact.
+every platform and contains no platform code. This is a refinement that makes the
+guarantee checkable, not an architectural departure.
+
+**Measured consequences.**
+
+- Bundled SQLite costs **~1.1 MB** of the 5 MB stripped daemon budget (1.364 MB
+  total, from 0.279 MB without it). That leaves 3.8 MB for D-Bus, X11 and a UI
+  toolkit — a real margin, not a comfortable one.
+- The build compiles SQLite from C source, which is a noticeable first-build cost.
+- System-linking would reclaim most of the 1.1 MB at the price of a runtime
+  dependency on the host's libsqlite3, and a schema-format mismatch that only
+  appears on a user's machine.
+
+**Still open:** bundled vs system-linked. Measured cost is now known; the decision
+is the owner's.
+
+**Schema notes.** Relational (`schedule_target`, `schedule_condition`) rather than
+JSON blobs in a text column, 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 (ADR-13).
 
 ---
 

docs/LIMITATIONS.md

@@ -177,9 +177,9 @@ not mistaken for platform facts.
 - **`ProcessBackend` is not implemented.** ADR-14 lists three backends; the KWin
   and X11 paths land in M2-Linux, and the process fallback is weaker than the
   spec assumes because of the `/proc/connectors` gap above.
-- **`rusqlite` has not been added.** The schema is written and reviewed in
+- **`rusqlite` vs system-linked SQLite is unresolved** (ADR-4). Bundled is built
-  `core/src/storage.rs` (ADR-4) but storage has no I/O behind it yet, so nothing
+  and costs ~1.1 MB of the 5 MB daemon budget. System-linking would reclaim most
-  persists. A restart loses all state.
+  of that but adds a runtime dependency on the host's libsqlite3.
 - **Lock state is not yet persisted or enforced.** `core/src/lock.rs` has the
   timers, the escalation, and the wall-clock correction, all tested. The state
   machine is not yet driven from a UI, and `LockState::evaluate` currently returns
@@ -188,6 +188,8 @@ not mistaken for platform facts.
   `tests/src/golden.rs`; parsing needs serde, which is a dependency decision
   awaiting sign-off (ADR-13, ADR-16). The behavioural coverage that exists today
   is hand-written unit tests in the same spirit.
+- **`LockState` still always evaluates to `Normal`** — persistence works, but no
+  UI drives the lock state machine yet.
 - **`Condition::UsageLimit` and `LaunchCount` sum across all targets** rather
   than the schedule's own target set, until targets carry usage keys.
 - **Windows is entirely unimplemented** and cannot be compiled or tested on the

docs/PERF.md

@@ -29,17 +29,26 @@ Measured on: Ubuntu 26.04 LTS, KDE Plasma 6.6.6, 6 CPUs. Toolchain: rustc 1.98.1
 
 | Metric | Target | Measured | When |
 |---|---|---|---|
-| Daemon binary (stripped, release) | ≤ 5 MB | **0.279 MB** | 2026-10-01, M0 |
+| Daemon binary (stripped, release) | ≤ 5 MB | **1.364 MB** | 2026-10-01, M1 |
 | Block latency | ≤ 150 ms | not measured | — |
 | Idle CPU | ~0% | not measured | — |
 | Idle RAM (daemon) | ≤ 15 MB RSS | not measured | — |
 | Idle wakeups | ≤ 1/min | not measured | — |
 | APK size | ≤ 10 MB | not measured | — |
 
-The binary figure is real but nearly meaningless right now: the daemon is two
+**What the 1.364 MB contains, and why it matters.** That figure is with bundled
-`println!` lines. The meaningful measurement comes in M2-Linux once enforcement
+SQLite linked in and the daemon actually opening a database — not the 0.279 MB
-exists, and the real risk is at that point — D-Bus, X11, and a UI toolkit are
+placeholder from M0, which was two `println!` lines and excluded SQLite entirely
-where 5 MB would actually be threatened.
+through dead-code elimination.
+
+So the honest read is: **bundled SQLite costs roughly 1.1 MB of a 5 MB budget.**
+That leaves 3.8 MB for D-Bus, X11, and the UI toolkit. It is a real constraint
+rather than a comfortable margin, and it is the first number that makes the
+section 5 budget feel like a budget instead of a formality.
+
+It also makes ADR-4 (rusqlite bundled vs system-linked) a genuine trade-off rather
+than a settled one: system-linking would recover most of that 1.1 MB at the cost
+of a runtime dependency on the host's libsqlite3. Recorded as an open question.
 
 ## How to measure