feat: SQLite migration

packages/session-backends/sqlite-node/src/sqlite/migrations/001_initial.sql

@@ -0,0 +1,79 @@
+-- AgentHarness storage format 4 / storageVersion 1.
+-- One SQLite database file represents exactly one session. Authoritative durable
+-- state is entries + registers + usage_ledger; branch_* and stats columns on
+-- session are maintained projections/caches.
+
+CREATE TABLE IF NOT EXISTS entries (
+	id TEXT PRIMARY KEY,
+	parent_id TEXT,
+	seq INTEGER NOT NULL,
+	type TEXT NOT NULL,
+	custom_type TEXT,
+	timestamp INTEGER NOT NULL,
+	payload TEXT NOT NULL
+) WITHOUT ROWID;
+
+CREATE INDEX IF NOT EXISTS ix_entry_parent ON entries(parent_id);
+CREATE INDEX IF NOT EXISTS ix_entry_seq ON entries(seq, type);
+
+CREATE TABLE IF NOT EXISTS registers (
+	namespace TEXT,
+	key TEXT,
+	seq INTEGER NOT NULL,
+	value TEXT NOT NULL,
+	PRIMARY KEY (namespace, key)
+) WITHOUT ROWID;
+
+CREATE TABLE IF NOT EXISTS usage_ledger (
+	id TEXT PRIMARY KEY,
+	seq INTEGER NOT NULL,
+	entry_id TEXT,
+	adjustment INTEGER NOT NULL,
+	usage TEXT NOT NULL,
+	details TEXT
+) WITHOUT ROWID;
+
+CREATE INDEX IF NOT EXISTS ix_usage_seq ON usage_ledger(seq);
+
+-- Private branch index. Not registers; no equivalent in the other backends.
+CREATE TABLE IF NOT EXISTS branch_entries (
+	branch_id TEXT,
+	entry_id TEXT,
+	entry_seq INTEGER NOT NULL,
+	entry_type TEXT NOT NULL,
+	PRIMARY KEY (branch_id, entry_id)
+) WITHOUT ROWID;
+
+-- Ordered scans. entry_seq must follow branch_id directly or ORDER BY needs a
+-- temp b-tree; entry_id and entry_type trail so the index covers id-only reads.
+CREATE INDEX IF NOT EXISTS ix_be_seq ON branch_entries(branch_id, entry_seq, entry_id, entry_type);
+-- Type-filtered scans.
+CREATE INDEX IF NOT EXISTS ix_be_type ON branch_entries(branch_id, entry_type, entry_seq, entry_id);
+CREATE INDEX IF NOT EXISTS ix_be_entry ON branch_entries(entry_id);
+
+CREATE TABLE IF NOT EXISTS branch_meta (
+	branch_id TEXT PRIMARY KEY,
+	tip_entry_id TEXT NOT NULL,
+	tip_seq INTEGER NOT NULL,
+	base_branch_id TEXT,
+	base_seq INTEGER
+) WITHOUT ROWID;
+
+CREATE UNIQUE INDEX IF NOT EXISTS ix_bm_tip ON branch_meta(tip_entry_id);
+
+-- One row each: the file is the session.
+CREATE TABLE IF NOT EXISTS session (
+	created_at INTEGER NOT NULL,
+	parent_session_id TEXT,
+	storage_version INTEGER NOT NULL,
+	metadata TEXT,
+	message_count INTEGER NOT NULL,
+	usage_payload TEXT NOT NULL,
+	next_seq INTEGER NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS writer_lease (
+	owner_id TEXT NOT NULL,
+	fence INTEGER NOT NULL,
+	expires_at_ms INTEGER NOT NULL
+);