code refactor

Reviewed-on: #26

crates/adapters/sqlite/migrations/0100_event_queue.sql

@@ -0,0 +1,13 @@
+CREATE TABLE IF NOT EXISTS event_queue (
+    id              INTEGER PRIMARY KEY AUTOINCREMENT,
+    event_type      TEXT    NOT NULL,
+    payload         TEXT    NOT NULL,
+    status          TEXT    NOT NULL DEFAULT 'pending',
+    attempts        INTEGER NOT NULL DEFAULT 0,
+    created_at      TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
+    next_attempt_at TEXT    NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
+    last_error      TEXT
+);
+
+CREATE INDEX IF NOT EXISTS idx_event_queue_poll
+    ON event_queue (status, next_attempt_at);

crates/adapters/sqlite/migrations/0101_outbox_identity.sql

@@ -0,0 +1,29 @@
+-- Outbox identity: every queued event carries a stable id; handlers claim
+-- (event_id, handler) pairs so redeliveries are skipped and concurrent
+-- deliveries never run the same handler twice.
+ALTER TABLE event_queue ADD COLUMN event_id TEXT;
+
+-- When the current claim started; a claim older than the lease is reclaimable.
+ALTER TABLE event_queue ADD COLUMN claimed_at TEXT;
+
+-- Legacy rows get a random v4-shaped uuid. The subquery references the row id
+-- so it is re-evaluated per row rather than cached.
+UPDATE event_queue SET event_id = (
+    SELECT lower(
+        substr(h, 1, 8) || '-' || substr(h, 9, 4) || '-4' || substr(h, 14, 3) || '-'
+        || substr('89ab', (abs(random()) % 4) + 1, 1) || substr(h, 18, 3) || '-' || substr(h, 21, 12)
+    )
+    FROM (SELECT hex(randomblob(16)) AS h, event_queue.id AS row_id)
+);
+
+CREATE UNIQUE INDEX idx_event_queue_event_id
+    ON event_queue (event_id) WHERE event_id IS NOT NULL;
+
+CREATE TABLE processed_events (
+    event_id     TEXT NOT NULL,
+    handler      TEXT NOT NULL,
+    status       TEXT NOT NULL CHECK (status IN ('in_progress', 'done')),
+    started_at   TEXT,
+    processed_at TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
+    PRIMARY KEY (event_id, handler)
+);

crates/adapters/sqlite/migrations/0102_account_deletion.sql

@@ -0,0 +1,9 @@
+ALTER TABLE users ADD COLUMN deleted_at TEXT;
+-- Set once the account's data is purged; the stripped row (and the signing
+-- keypair) stays until the tombstone cleanup removes it.
+ALTER TABLE users ADD COLUMN purged_at TEXT;
+
+CREATE TABLE retired_usernames (
+    username TEXT PRIMARY KEY COLLATE NOCASE,
+    retired_at TEXT NOT NULL DEFAULT (strftime('%Y-%m-%dT%H:%M:%SZ', 'now'))
+);