2.4 compatibility in Nexa 3.0

This page describes the retained 2.4 language/runtime path. Sources without a version declaration use this path. Start new Open Programs with Nexa 3.0; compare contracts in the migration guide.

Services and durable tasks

Nexa includes HTTP services, background jobs, databases, KV, authentication, templates, and concurrency modules. Distinguish application-module capabilities from durable Agent execution guarantees when designing deployment.

Capability	Runtime entry	Test provenance
HTTP routing	nexa serve / routes, src/runtime/http_server.py	tests/test_http_server.py
Background jobs	nexa jobs / workers, src/runtime/jobs.py	tests/test_jobs.py
Databases	std.db.sqlite / std.db.postgres	tests/test_database.py
KV	std.kv	tests/test_kv_store.py
Authentication/CSRF	std.auth	tests/test_auth.py
Templates	std.template	tests/test_template.py

Applications own configuration and external dependencies for these modules. Deployment high availability, tenant isolation, and operational SLAs require application-level design and acceptance against real traffic, storage, permissions, and failures.

Agent execution layer

Tool execution persists started first and saves results before appending messages. SQLite revisions detect conflicting writes. See Execution and Checkpoints for approvals, budgets, and unknown outcomes.

Database transactions cover their database operations. Workflows spanning HTTP, files, and model calls need application-defined idempotency keys, compensation, and operator verification.

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Source and validation · stdlib / execution / checkpoint