Context, Memory & Run State

package com.interviewpreparator.agents;
import java.util.List;
import org.springframework.jdbc.core.JdbcTemplate;
import tools.jackson.databind.json.JsonMapper;
import static com.interviewpreparator.agents.AgentContracts.*;
public final class JdbcRunStore implements RunStore {
    private final JdbcTemplate jdbc;
    private final JsonMapper mapper = JsonMapper.builder().build();
    public JdbcRunStore(JdbcTemplate jdbc) { this.jdbc = jdbc; }
    public void initializeLocalSchema() {
        // Teaching/local setup only. Production schema changes belong in migrations.
        jdbc.execute("""
            create table if not exists agent_runs (
                tenant text not null, owner_id text not null, conversation text not null,
                run_id text not null, version bigint not null, state_json text not null,
                primary key (tenant, owner_id, conversation, run_id))
            """);
    }
    @Override public Snapshot createOrLoad(Scope scope, State initial) {
        jdbc.update("""
            insert into agent_runs (tenant, owner_id, conversation, run_id, version, state_json)
            values (?, ?, ?, ?, 0, ?) on conflict do nothing
            """, scope.tenant(), scope.user(), scope.conversation(), scope.runId(), mapper.writeValueAsString(initial));
        List<Snapshot> rows = jdbc.query("""
            select version, state_json from agent_runs
            where tenant=? and owner_id=? and conversation=? and run_id=?
            """, (result, index) -> new Snapshot(result.getLong(1), mapper.readValue(result.getString(2), State.class)),
                scope.tenant(), scope.user(), scope.conversation(), scope.runId());
        if (rows.size() != 1) throw new Conflict();
        return rows.getFirst();
    }
    @Override public Snapshot save(Scope scope, long expectedVersion, State state) {
        long next = Math.addExact(expectedVersion, 1);
        int changed = jdbc.update("""
            update agent_runs set version=?, state_json=?
            where tenant=? and owner_id=? and conversation=? and run_id=? and version=?
            """, next, mapper.writeValueAsString(state), scope.tenant(), scope.user(), scope.conversation(), scope.runId(), expectedVersion);
        if (changed != 1) throw new Conflict();
        return new Snapshot(next, state);
    }
}