SQLite storage layer implementation

[tac0turtle]

Summary

Implement the SQLite-based storage layer (pkg/store/) as defined in the design doc. This is the foundational persistence layer all other components depend on.

Schema

CREATE TABLE sync_state (
    id INTEGER PRIMARY KEY CHECK (id = 1),
    last_synced_height INTEGER NOT NULL DEFAULT 0,
    start_height INTEGER NOT NULL,
    updated_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE headers (
    height INTEGER PRIMARY KEY,
    hash BLOB NOT NULL,
    data_hash BLOB NOT NULL,
    raw_header BLOB NOT NULL,
    time TIMESTAMP NOT NULL
);

CREATE TABLE blobs (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    height INTEGER NOT NULL,
    namespace BLOB NOT NULL,
    commitment BLOB NOT NULL,
    data BLOB NOT NULL,
    share_version INTEGER NOT NULL,
    signer BLOB,
    blob_index INTEGER NOT NULL,
    UNIQUE(height, namespace, commitment)
);

CREATE INDEX idx_blobs_ns_height ON blobs(namespace, height);

CREATE TABLE namespaces (
    namespace BLOB PRIMARY KEY,
    name TEXT,
    enabled BOOLEAN DEFAULT TRUE
);

Requirements

• Store interface in pkg/store/store.go
• SQLite implementation in pkg/store/sqlite.go
• Schema migrations (embed SQL via embed package)
• Methods: InsertHeader, InsertBlobs, GetBlobsByHeight, GetBlob (by height+ns+commitment), GetHeader, GetSyncState, UpdateSyncState
• WAL mode enabled for concurrent read/write
• Connection pooling via database/sql
• Unit tests with in-memory SQLite

References

• Design doc: test_plan.md — Storage Design section