zymi-core 0.6.3

Event-sourced agent engine — CLI and Python bindings for auditable AI workflows

zymi-core

dbt for AI workflows — declarative agents, deterministic replay, human-in-the-loop, all from YAML.

_{Pronounced zoomi — like dog zoomies.}

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Why zymi-core?

Most agent frameworks are imperative Python: write a script that makes LLM calls, persist some messages, hope you logged enough to debug a bad run later.

zymi-core inverts that:

• Declarative, like dbt. Agents, pipelines, tools, connectors, approvals — all YAML. The engine validates and runs them as a DAG.
• Event-sourced. Every state change is an immutable, hash-chained event. Runs are replayable, resumable, and auditable without extra logging.
• Boundary-safe. Agents emit intentions (run shell, write file, call HTTP) that pass through policy + contracts + optional human approval before execution. The risky thing doesn't happen until someone says yes.

Bring a useful agent online in minutes without writing code. A year later, still answer exactly what this agent did on any past run.

📚 AI-assistant friendly out of the box. Every zymi init scaffold drops an AGENTS.md into the user's project — vocabulary, file map, task→file routing. Claude Code / Cursor / Aider read it automatically; the YAML they help you write gets noticeably more correct.

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Run a Telegram agent in two minutes

This is the canonical demo — a real chat bot, wired declaratively.

pip install zymi-core

mkdir telegram-agent && cd telegram-agent
zymi init --example telegram

# 1. Create a bot via @BotFather in Telegram; copy the token.
# 2. Fill .env:
cp .env.example .env       # edit TELEGRAM_BOT_TOKEN + OPENAI_API_KEY
# 3. Open project.yml, replace "your_username_here" with your actual
#    Telegram username (no @). Keeps strangers out of the bot.

set -a; source .env; set +a
zymi serve chat

Message the bot. It replies in seconds. Every inbound message, LLM call, approval decision, and outbound reply is in .zymi/events.db; watch live with zymi observe.

The whole wiring — Telegram I/O, two-step DAG (assistant drafts, reviewer polishes), declarative + Python tools, approval channel — lives in YAML. The scaffold also drops AGENTS.md so an AI coding assistant can extend the project safely. Concrete demo of:

• http_poll connector — long-polls Telegram's getUpdates, no HTTPS / ngrok needed
• http_post output — sends each ResponseReady back to the user
• Telegram approval channel — DMs admins with ✅ / ❌ buttons when the agent calls broadcast (requires_approval: true)
• Python @tool auto-discovery — drop tools/get_weather.py (sync) or tools/translate.py (async) and the agent picks them up

Ask the bot to "announce that we're closing at 5pm" — the agent calls broadcast, you get a DM with approve/deny buttons, nothing goes out until you click. End-to-end audit trail in zymi events.

Full setup in docs/getting-started.md. Connector deep-dive in docs/connectors.md. Approvals in docs/approvals.md.

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What's in the box

Pipelines — DAGs, agent steps, deterministic tool steps

A pipeline is a list of steps with depends_on: edges. Independent steps run in parallel. Each step is either an agent step (LLM ReAct loop) or a deterministic tool step (ADR-0024) — direct dispatch with templated args, no LLM hop, but the same event envelope.

Mix them freely:

steps:
  - id: fetch                            # deterministic — no LLM
    tool: http_get
    args: { url: "https://api.example.com/${inputs.id}" }

  - id: classify                         # LLM
    agent: classifier
    task: "${steps.fetch.output}"
    depends_on: [fetch]

Schema, examples, gotchas → docs/pipelines.md.

Tools — four kinds, one catalogue

All four kinds emit identical ToolCallRequested / ToolCallCompleted events; the agent doesn't know which catalogue a tool came from.

• Declarative HTTP / shell in tools/<name>.yml — no code.
• Python @tool in tools/<name>.py — sync or async, signature → JSON Schema, auto-discovered.
• MCP servers — one mcp_servers: entry gives N tools, namespaced mcp__<server>__<tool> (ADR-0023).
• Builtins — read_file, write_file, write_memory, execute_shell_command, spawn_sub_agent.

# tools/get_weather.py — auto-discovered at runtime startup.
from zymi import tool

@tool
def get_weather(city: str) -> str:
    """Return the current weather for a city."""
    return f"sunny in {city}"

Schema and the four kinds in detail → docs/tools.md.

Connectors and outputs

Inbound: http_inbound (webhook), http_poll (long-poll), cron, file_read, stdin. Outbound: http_post, file_append, stdout.

All declarative, all emit events. Filter recipes (docs/connectors.md):

# GitHub — only react to PR opens
filter:
  "$.action":              { equals: "opened" }
  "$.pull_request.draft":  { equals: false }

429 + Retry-After handled automatically. Cursors persist across restarts. Multi-process zymi serve against shared Postgres sees one cursor table, no double-fire.

Approvals — event-sourced, restart-safe

Tools with requires_approval: true publish ApprovalRequested on the bus; an approval channel routes a human decision back. Three channels in the box: terminal, http, telegram (ADR-0022).

Resolution order: pipeline override → project default → fail-closed. A zymi serve crash mid-approval is repaired on next start: in-flight requests are redelivered to live channels; expired ones are sealed with ApprovalDenied{reason: restart_timeout}.

Full schemas + telegram setup → docs/approvals.md.

Replay, resume, observe

zymi runs                                   # all pipeline runs
zymi events --stream pipeline-chat-abc      # every event in one run
zymi verify --stream pipeline-chat-abc      # hash-chain integrity check
zymi observe                                # 3-panel TUI: runs / DAG / events live

# Fork-resume from a chosen step. Upstream steps are frozen; the fork
# step + DAG-descendants re-run against current configs on disk.
zymi resume pipeline-chat-abc --from-step polish
zymi resume pipeline-chat-abc --from-step polish --dry-run

Useful when you're iterating on a prompt: don't re-burn the expensive early steps every time you tweak the later ones. → docs/events-and-replay.md.

Store backends

SQLite (default, zero-config) for single-process / dev. Postgres for multi-process zymi serve against shared state — one store: postgres://… line in project.yml (ADR-0012). Same hash-chain semantics either way. → docs/store-backends.md.

Context window management

The agent's working context is reconstructed from the event log each iteration, not accumulated in a buffer. Older tool observations are masked in-place (~2× cost reduction, no extra LLM calls). When the budget still gets tight, hybrid compaction summarises the oldest masked batch with one fast LLM call. Tunable in runtime.context: (ADR-0016).

JSON Schemas for configs

IDE autocomplete and LLM-assisted YAML come free:

zymi schema project          # draft-07 JSON Schema for project.yml
zymi schema --all

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Python embedding

The same pip install zymi-core exposes a Python API: Runtime, Event, EventBus, EventStore, Subscription, ToolRegistry, plus the @tool decorator.

from zymi import Runtime

rt = Runtime.for_project(".", approval="terminal")
result = rt.run_pipeline("chat", {"message": "hello"})
print(result.success, result.final_output)

rt.bus() and rt.store() share Arc-handles with the runtime — Python subscribers see exactly what the handler publishes.

Cross-process pattern (Django view / Celery task drives zymi serve over the shared store):

import uuid
from zymi import Event, EventBus, EventStore

store = EventStore(".zymi/events.db")
bus = EventBus(store)

corr = str(uuid.uuid4())
sub = bus.subscribe_correlation(corr)

ev = Event(
    stream_id=f"web-{corr}",
    kind={"type": "PipelineRequested",
          "data": {"pipeline": "research", "inputs": {"topic": "rust event sourcing"}}},
    source="django",
)
ev.with_correlation(corr)
bus.publish(ev)

result = sub.recv(timeout_secs=300)

Full surface → docs/python-api.md.

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CLI cheatsheet

zymi init [--example telegram]              # scaffold a project
zymi run <pipeline> -i key=value …          # one-shot run
zymi serve <pipeline>                       # long-running: react to PipelineRequested

zymi runs                                   # list pipeline runs
zymi events [--stream ID] [--kind TAG]      # query event log
zymi verify [--stream ID]                   # hash-chain integrity check
zymi observe [--run ID]                     # interactive TUI
zymi resume <run-id> --from-step <id>       # fork-resume

zymi mcp probe <name> -- <cmd> [args …]     # smoke an MCP server
zymi schema {project|agent|pipeline|tool|--all}

Full reference → docs/cli.md.

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Documentation

• Getting started — install → init → first run
• Project YAML — project.yml schema
• Agents · Pipelines · Tools
• Connectors · Approvals · Store backends
• Events and replay · CLI reference · Python API
• llms.txt — flat index of this documentation tree for LLM scrapers and RAG tools
• AGENTS.md — agent-onboarding doc generated by zymi init into each new project (vocabulary, file map, task→file routing)
• adr/ — architectural decision records, one short markdown file per decision

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Contributing & License

zymi-core is built in Rust and shipped via PyPI. Bug reports, examples, PRs welcome — see CONTRIBUTING.md for the dev loop, test matrix, ADR workflow, and how to build from source.

MIT — see LICENSE.