Constant CORE_DDL 

pub const CORE_DDL: &str = "
CREATE TABLE IF NOT EXISTS sessions (
    id              TEXT PRIMARY KEY,
    kind            TEXT NOT NULL CHECK (kind IN ('debug','profile')),
    target          TEXT NOT NULL,
    target_class    TEXT NOT NULL,
    target_hash     TEXT,
    started_at      TEXT NOT NULL,
    ended_at        TEXT,
    label           TEXT NOT NULL,
    created_by      TEXT NOT NULL DEFAULT 'auto'
);

CREATE TABLE IF NOT EXISTS layers (
    id              INTEGER PRIMARY KEY,
    session_id      TEXT NOT NULL REFERENCES sessions(id),
    source          TEXT NOT NULL,
    file            TEXT,
    collected_at    TEXT,
    command_used    TEXT,
    collection_secs REAL,
    target_hash     TEXT
);
CREATE INDEX IF NOT EXISTS idx_layers_session ON layers(session_id);

CREATE TABLE IF NOT EXISTS symbols (
    id              INTEGER PRIMARY KEY,
    session_id      TEXT NOT NULL REFERENCES sessions(id),
    lang            TEXT NOT NULL,
    fqn             TEXT NOT NULL,
    file            TEXT,
    line            INTEGER,
    demangled       TEXT,
    raw             TEXT NOT NULL,
    is_synthetic    INTEGER NOT NULL DEFAULT 0,
    UNIQUE(session_id, lang, fqn)
);
CREATE INDEX IF NOT EXISTS idx_symbols_fqn ON symbols(lang, fqn);

CREATE TABLE IF NOT EXISTS meta (
    session_id      TEXT NOT NULL REFERENCES sessions(id),
    key             TEXT NOT NULL,
    value           TEXT,
    PRIMARY KEY (session_id, key)
);

CREATE TABLE IF NOT EXISTS failures (
    session_id      TEXT NOT NULL REFERENCES sessions(id),
    phase           TEXT,
    error           TEXT
);

CREATE TABLE IF NOT EXISTS regions (
    id              INTEGER PRIMARY KEY,
    session_id      TEXT NOT NULL REFERENCES sessions(id),
    name            TEXT NOT NULL,
    start_us        REAL,
    duration_us     REAL,
    thread          TEXT,
    layer_id        INTEGER REFERENCES layers(id)
);
CREATE INDEX IF NOT EXISTS idx_regions_session ON regions(session_id);

CREATE TABLE IF NOT EXISTS allocations (
    id              INTEGER PRIMARY KEY,
    session_id      TEXT NOT NULL REFERENCES sessions(id),
    op              TEXT NOT NULL,
    address         INTEGER NOT NULL,
    bytes           INTEGER NOT NULL,
    start_us        REAL,
    heap            TEXT NOT NULL DEFAULT 'default',
    thread          TEXT,
    stack_json      TEXT,
    layer_id        INTEGER REFERENCES layers(id)
);
CREATE INDEX IF NOT EXISTS idx_alloc_addr ON allocations(session_id, address);
CREATE INDEX IF NOT EXISTS idx_alloc_time ON allocations(session_id, start_us);
";

Shared meta tables — always created regardless of track or target class.