You keep the taste. Agents do the rest.
Delta is the open source runtime for long-running autonomous agents. You hold the judgment and the last word. It systematizes the knowledge work beneath you.
Why Delta
Humans orchestrate. Agents systematize.
You hold judgment, priorities, and the last word. Delta turns the repeatable knowledge work beneath that into a system that runs itself.
Two ways to run it
Run your own agents
Autonomous agents that learn as they work and live on your own infrastructure.
Ship an agentic feature
A model-agnostic, self-learning agent that does one job inside your product.
01 · Anatomy
One engine. Any agent.
Every agent is the same engine plus a five-file bundle plus its state. The code is generic, the agent is data.
// Bun binary, under 10ms cold start, zero runtime deps. The same binary runs every agent.
the mind
the wiring
// A new agent is a new bundle, not a new build. One fix to the loop reaches every agent.
SQLite (WAL)
workspace (on disk)
per-run · ephemeral (store: false)
cross-run · survives
02 · Run loop & spine
Every turn rebuilds from a 2,000-token spine
A loop that rebuilds, calls, acts, and checkpoints every turn. A spine that fits the whole identity in under 2,000 tokens.
// budgets, not timers. tokens counted fresh (non-cached) only. hit any ceiling and the run finalizes cleanly, it never crashes.
The spine · under 2,000 tokens
// the order matters: the writable self can never appear after, and override, the fixed policy.
03 · Tools & context
Everything is a tool. Every request stays under the ceiling.
The agent acts only through tools, and two mechanics keep every assembled request beneath its token ceiling, however long the run goes.
A · Tools & the seam
files
memory & plan
work
delegation
discoverable via search_tools
The seam
// one binary, one agent per process or VM
B · Context management
// same run, request rebuilt under the ceiling. detail is not lost, only moved to disk where the agent can recall it.
Compaction
Older turns fold into a structured note. The recent tail stays verbatim, and prior summaries merge forward.
Spill
A result over ~20k bytes writes to a file, leaving a pointer. Recall it later at full fidelity, near-zero tokens.
The honest edge. One agent can still pull a huge transcript plus dozens of mid-size results into a single window and brush the ceiling, burning budget. That exact failure is what subagents, next, are built to defeat.
04 · Sub-agents △ new in v0.2.0
The planner keeps the signal, not the noise
One master planner commissions up to three sub-agents in parallel. Each works in a fresh, isolated context and returns only distilled signal.
// signal returns to the planner. noise stays on disk, recalled only when a decision needs the detail.
inherited from parent
withheld
// withholding these is what keeps nesting exactly one level deep. no fork-bombs.
New in 0.2.0, children hold the parent's exact rights and are forged from the same spine, so they inherit the same norms and policy. Same rights, and same rules.
05 · Memory & learning
It learns, and it survives.
The agent turns human corrections into durable lessons, then recovers from restarts, drops, and slow turns on its own.
The agent proposes. A human approves.
Writes to shared systems are proposals the human dispositions. The human keeps the last word, and every disposition feeds the next lesson.
06 · Durability & resilience
It survives the real world
Restarts, dropped connections, and slow turns are recoverable events here, not failures.
Crash-safe
The WAL commits after every turn, so a restart resumes from the last committed turn. Nothing lost, nothing double-run.
Self-healing
Long tasks dispatch fire-and-forget over /v1/tasks. A reconciler sweep re-drives anything stuck, and a budget-hit run retries clean.
Never crashes
A provider or tool failure returns a clean turn the agent can reason about. The daemon does not fall over.
A proxy caps long-held connections, orphaning durable runs.
Move to idempotent async dispatch.
The reconciler clears the backlog on its own. A budget-death re-drives and files on retry.