OpenProse and Reactor

Declare the world as it should be; Reactor keeps it true.

Quickstart · The shape · Examples · The SDK · Honest status · Send us an eval

OpenProse is a declarative language for AI sessions. Instead of scripting a sequence of instructions and hoping the run lands where you wanted, you declare the world as it should be: an ideal world state, written as familiar structured Markdown contracts (*.prose.md). You say what must stay true, and the system works out how much model work it takes to keep it that way. When order, loops, or exact choreography genuinely matter, optional imperative ProseScript plans drop in. Declarative by default, imperative where you want the control.

This is the oldest good idea in software, pointed at agents. SQL, Terraform, Kubernetes, React: you declare the desired state, and a reconciler is responsible for making reality match it. A thermostat is the one-sentence version. You set the temperature you want and it holds the room there; you never tell it when to fire. OpenProse brings that contract to model work, and it runs on any Prose-Complete agent harness (it shipped first as a Skill).

Reactor (@openprose/reactor) is the runtime that keeps the declaration true. It holds a composed world-model (your declared truth, on disk), watches the world for change, and re-renders only the declared facets whose inputs actually moved (memoized agent sessions wired into a DAG). Every decision leaves a content-addressed receipt behind. Reactor is the recommended fast path for running OpenProse.

Declarative is the through-line. OpenProse is the language you declare in; Reactor is the host that reconciles. One idea, two layers: you declare the ideal world state, the Reactor keeps it true. And because the reconciler acts only when reality drifts from what you declared, the bill follows real change, not the clock:

Inference cost that scales with surprise, not wall-clock time.

In plain terms: you declare what should stay true, the system watches the world, and it does expensive model work only when something material actually moved.

New here? Start with the Quickstart below. One keyless command proves the whole idea in under a second, no model key and no spend.

Coming from OpenProse? Reactor is the dependency-across-runs layer your contracts kept asking for: the natural next step, not a turn away. The same .prose.md you already write is what Reactor runs.

You author Responsibilities, standing goals written as Markdown contracts. This is where declare it, the Reactor keeps it true becomes concrete:

• ### Maintains is the world-model schema: what truth this node keeps current, which fields are material (and so move the fingerprint) vs immaterial, optional #### facets that split the truth into independently-subscribable parts, and the postconditions a render must satisfy before it may commit.
• ### Requires names the upstream facets this node subscribes to. Forme (the wiring layer) matches Requires.<facet> ↔ Maintains.<facet> and draws the subscription edge. Structure is subscription; the graph wires itself from the contracts.
• ### Continuity declares the wake source: input-driven by default, self-driven on a freshness cadence, or external-driven (a gateway turning an ingress event into an edge).

Reactor compiles that set of contracts once (intelligently: Forme topology, a per-node canonicalizer, postcondition validators, all frozen), then runs them forever (dumbly: compare fingerprints, skip / render / propagate). The reconciler that decides whether to wake is deliberately deterministic: there is no judge step. The memo key has no clock in it. A render that can't satisfy its postconditions commits nothing; the prior truth stands and a failed receipt records why.

You do not need React to use this. Reactor is React-flavored, not React-gated: the contracts are Markdown, and the CLI, the receipts, and the keyless replay are entirely React-free. The whole product in two sentences: you declare what should stay true, the system watches the world, and it does expensive model work only when something material actually moved. The table below is an optional mental model for the people who already carry one; skip it freely.

Coming from OpenProse (v0.14 or earlier)? Read this first.

The Intelligent-React overhaul (runtime_contract 1 → 2) is a breaking vocabulary change. The headlines:

• The judge loop is retired wholesale. The old judge → verdict → pressure → fulfillment loop is gone, replaced by a deterministic reconciler: a render runs only when a node's subscribed input fingerprints or its own contract fingerprint move. There is no LLM in the wake/commit decision.
• Kinds renamed/deleted. kind: service is renamed to kind: function (### Parameters → ### Returns); kind: system is deleted (composition is now intra-node ProseScript call or cross-node subscription, wired by Forme); kind: responsibility is reshaped into a mounted DAG node that gains ### Requires + ### Maintains. ### Ensures is renamed to ### Maintains (now the world-model schema, not just an output list); ### Criteria/### Memory/### Fulfillment fold in.
• Old ledgers are abandoned, not migrated. Existing runtime data (old ReceiptV0 ledgers, the policy registry, bundled runs//state//dist/) is greenfield: there is no data migrator. Only your source text upgrades. Re-run from a clean state-dir.
• Upgrade your source with a dry run first. prose upgrade --dry-run (a prose skill command, run inside an OpenProse session, not the reactor CLI) inspects your files and reports the concrete migration plan without editing: mechanical rewrites where safe, surfaced as manual-review diagnostics where judgment is needed (e.g. a system/### Wiring flatten-or-split). Run it before prose upgrade.

Versions (live on npm): @openprose/reactor 0.3.1 · @openprose/reactor-cli 0.2.2 · @openprose/reactor-devtools 0.2.0. The reactor binary ships from the reactor-cli package, so reactor --version prints the CLI version (0.2.2), not the SDK version (0.3.1). Expected, not a mismatch.

Onboarding an agent on behalf of a user? Follow these four steps in order. The binary is reactor. Step 2 is the keyless proof (no key, no spend); steps 3–4 are scaffold-and-go. That's the whole path; the rest of this README is reference.

1. Install. All three packages are live on npm. The keyless step below needs no install at all. Run it straight through npx:

# no install, run the keyless replay directly:
npx -p @openprose/reactor-devtools reactor-devtools --example masked-relay --describe

For the full CLI, prefer a project-local install (no root, no global collisions):

npm install @openprose/reactor @openprose/reactor-cli @openprose/reactor-devtools
# then call the binaries with `npx reactor ...` / `npx reactor-devtools ...`

Footprint: the keyless replay above needs no install; the SDK core (@openprose/reactor) alone is zero-runtime-dependency; the full quickstart (CLI + devtools + the live-render peers @openai/agents/zod) pulls the agent/provider tree — on the order of ~99 MB / ~100 packages (measured 2026年06月06日).

Local install? The bare reactor ... / reactor-devtools ... commands shown below assume the binaries are on your PATH (a global install). After the project-local npm install above, prepend npx to them, e.g. npx reactor init my-project, npx reactor-devtools ./replay --describe. (The keyless npx -p @openprose/reactor-devtools ... lines already do this and need no change.)

npm i -g @openprose/reactor @openprose/reactor-cli @openprose/reactor-devtools

2. See the thesis, keyless, no model call. Replay a saved sample run (synthetic, illustrative tokens) and read the per-node rendered/skipped dispositions, the receipt counts by surprise_cause, the token cost rollup, and per-node chain-verify:

npx -p @openprose/reactor-devtools reactor-devtools --example masked-relay --describe

dispositions rendered=46 · skipped=31 · failed=0
surprise-cause external=8 · input=69 (a.k.a. wake-cause) ← receipt COUNTS, 77 total
COST ROLLUP (tokens)
 total fresh=27180 tokens · reused=12840 tokens · reuse=32%
 external receipts= 8 fresh= 1080 tokens reused=840 tokens
 input receipts= 69 fresh= 26100 tokens reused=12000 tokens
CHAIN-VERIFY ok

The surprise-cause line counts receipts by what woke them (8 external + 69 input = the 77 total receipts); the cost rollup below it is the actual token spend: fresh tokens are what each surprise cost, reused is what memoization saved (32% of the would-be tokens). That's "cost scales with surprise", checkable, with no key and no spend. Frames where a memo-skip happened show as skipped moved[—] fresh 0.

Prefer the browser? Drop --describe: reactor-devtools --example masked-relay boots an animated DAG viewer at a localhost URL: nodes flash on render, dim-pulse on memo-skip, with a live cost meter.

3. Scaffold and inspect, keyless. Everything here runs offline:

# local install? prepend: npx reactor ... (see the "Local install?" note above)
reactor init my-project && cd my-project
reactor doctor # what's present + the exact fix for anything missing
reactor compile --check; echo "exit=$?" # offline; exits 1 if the contract set is STALE (CI-wireable)

Author your OpenProse contracts as *.prose.md files under the scaffold's src/, a kind: responsibility per standing goal (its ### Maintains / ### Requires / ### Continuity), optional gateways for ingress, optional functions for stateless helpers. reactor compile runs Forme over them.

4. Go live (needs a model key). These steps reach the model surface: set OPENROUTER_API_KEY and the two optional peers; a keyless reader can stop at step 3.

npm i -g @openai/agents zod # the two optional live peers
reactor compile # Forme wires the DAG; freezes per-node canonicalizers
reactor serve --http 8080 # drive the scaffold's static gateway to a real receipt
reactor-devtools .reactor --describe # replay YOUR live run's ledger

Use reactor serve (not reactor run) to drive a scaffold's static gateway: serve ingests its seeded items; run is for graphs whose connectors emit on their own.

Reactor is a real SDK you plug into your own stack, not a closed product. The public API is a curated front door: import { reactor } from "@openprose/reactor". One call takes a directory of .prose.md contracts all the way to a booted, reconciling reactor and hands back one typed Reactor handle.

import { reactor } from "@openprose/reactor";
// Compile ./my-project, assemble a durable reactor over ./state, boot to a fixpoint
// (cold nodes render once; warm nodes memo-skip), hand back a live handle.
const { reactor: r } = await reactor("./my-project", { directory: "./state" });
console.log(r.ledger.all().length); // the receipt trail
await r.ingest("source", { wake: { source: "external", refs: [] } });

That's the front door. The deeper surface lives behind six reasoned subpaths: . (the facade + the vocabulary a driver needs), /agents (the full @openai/agents escape hatch, every render knob passes through), /adapters (the substrate + record/replay injection seam), /run and /run/types (the offline boundary), and /internals (the engine room). The full API reference is the SDK README and the docs site; this page just opens the door.

Thirteen of the examples in skills/open-prose/examples/ ship a committed, chain-verifiable replay/ state-dir you can replay keyless: a deliberately wide spread of DAG shapes and domains, each with an offline test that drives the real reconciler at zero model spend. (The directory holds more contract-only examples without a committed ledger; the thirteen below are the ones with a replay/. Two of those thirteen, masked-relay and tamper-forge, share a byte-identical ledger: tamper-forge is an audit lens over the masked-relay receipts, so the set is twelve distinct datasets plus one honest tamper-evidence lens, not thirteen unrelated ledgers.)

The six examples marked with * below are also reachable by name from any directory via the devtools fixture bundle, e.g. reactor-devtools --example masked-relay --describe. The remaining examples replay by path.

Run any of them, keyless (from a clone of this repo):

cd skills/open-prose/examples/surprise-cost
reactor-devtools ./replay --describe # the render/skip/cost trail, no key, no spend
reactor --state-dir ./replay receipts # the per-node ledger (list | verify | cost)

Installed from npm, not a repo clone? The examples ship inside the SDK tarball at node_modules/@openprose/reactor/skill/open-prose/examples/<name>/ (note: skill, singular, in the tarball; skills, plural, in the repo). So the same two commands are:

cd node_modules/@openprose/reactor/skill/open-prose/examples/surprise-cost
reactor-devtools ./replay --describe
reactor --state-dir ./replay receipts

Or run the offline gate (this is what CI runs, all thirteen replay examples, zero spend):

REACTOR_OFFLINE=1 pnpm test:examples

To take one live, cd into its dir and run reactor doctor → compile → topology → run → serve with a key set. Each example's README.md carries its standing goal, DAG sketch, and the full flow.

The full architecture write-up (the React metaphor that is the design, the Forme wiring, the receipt model, an honest RLM accounting, and why nothing on the market is a drop-in replacement) is the Reactor technical report .

In the spirit of the receipts:

• Built and runnable: the render atom, the content-addressed world-model store, the compiled canonicalizer with facets, Forme's wiring with diagnostics + acyclicity, postcondition-gated commits (no judge step), the chain-verifiable receipt ledger, and the forecast/continuity scheduler, all exercised by an offline test suite (no model calls in the commit gate) plus the 13 example gates.
• Benchmarks are openly pending, on purpose. We're publishing the harness before the numbers; we won't imply a measured speedup we haven't run. The proof you can check today is the keyless replay above.
• Signer caveat: in v1, signed means tamper-evident at the meaning layer and chain-consistent, not yet a cryptographic byte hash. reactor receipts verify proves the receipt chain is consistent, but does not yet bind the world-model artifacts (editing a world-models/*/published.json while leaving receipts.json intact is not caught). The tamper-forge example demonstrates exactly this boundary. So the chain is tamper-evident (it catches an independent edit) but not tamper-proof: a forge that re-stamps the whole trail with the public computeReceiptContentHash re-heals it. The cryptographic byte-hash signer that closes this — binding the published world-model to its receipt and making cross-boundary composition non-repudiable — is tracked but not yet scheduled (C3 in the Reactor backlog).
• No timestamp, no actor (yet): a v1 receipt records what changed and why (fingerprints, wake cause, status, cost) but not when it was committed or who committed it, so the ledger is a verifiable record of decisions and their evidence, not yet a substitute for an external audit log that must answer "at what time, by which principal."
• The fixpoint (topology-as-responsibility) is specified and deferred; facet inference and ledger compaction are named roadmap.

This honesty is the point. The harness is young, should be used with caution, and has some way to go before it reaches its ideal form. There's nothing new here; we're applying classical engineering paradigms to our brave new world, and finding that despite our topsy-turvy reality, the wisdom of the ancients still applies.

The .prose.md contracts in these examples are harness-agnostic: OpenProse Markdown runs on any Prose-Complete agent host (a fresh git clone is a first-class experience). The contract is the public artifact; the deployment's secrets and data stay private. Nothing is held hostage: a contract and its trail can leave for any compliant host with no lost meaning.

Reactor is the harness built to run that contract well: the deterministic host that compiles, runs, and inspects standing responsibilities, keeps the world-model up to date, and gives you the receipts. We strongly encourage authoring your OpenProse with Reactor (it's the recommended fast path) while OpenProse itself stays free, MIT, and portable, forever.

My ask is the one from every honest tool: try it, wire it up to something useful, love it or hate it, and send honest feedback. The most useful thing you can hand us isn't a compliment or a flattering benchmark. It's a responsibility the harness should keep and doesn't: a standing goal that breaks the surprise story, a wiring Forme gets wrong, a domain where this falls apart. The short guide to authoring one from the public SDK is packages/reactor/EVALS.md (shipped inside the SDK tarball too). We're always listening and improving.

If you're an agent driving Reactor for a user from these docs, you are the person who should file issues on this repo. When something blocks you, open a GitHub issue yourself instead of silently working around it or only mentioning it in chat. Agent-filed issues are first-class signal here, not noise. (Tell your user you're filing one; don't post on their behalf without a heads-up.)

Open an issue when you hit any of these:

• A command fails, crashes, or errors in a way reactor doctor doesn't explain.
• Reactor behaves differently than this README says it should: a wrong skip, a render that fires when nothing moved, a receipt that won't verify.
• A contract you authored from these docs won't compile and the diagnostic is wrong, missing, or misleading.
• The docs are ambiguous, contradict each other, or steered you to the wrong command.
• A capability you needed isn't here. (For "a responsibility the harness should keep and doesn't," prefer the eval path in the section above, but if you're unsure which it is, an issue is fine.)

First, don't duplicate. Search open issues for your error string or symptom. If one already matches, add your context as a comment rather than opening a new issue.

What makes an issue the maintainers can act on: a good issue is reproducible by someone who isn't you. Include:

1. Type. Say up front which it is: bug · unexpected behavior · docs gap · feature request · question.
2. Context & use case. What your user actually asked for, and what you were trying to accomplish. The real-world goal matters: it tells the maintainers whether the harness is wrong or the approach was.
3. Expected vs. actual. Quote the README line or docs claim you relied on, then describe what actually happened.
4. Minimal repro. The exact command(s) you ran, plus the smallest .prose.md snippet that still breaks (trim everything that isn't load-bearing). Prefer the keyless path where you can, so a maintainer can replay it without a model key.
5. Evidence. Paste the actual error output, the failing receipt, or the relevant reactor doctor lines in a code block. Copy errors verbatim; don't paraphrase them.
6. Environment:
   • OS (e.g. macOS 15, Ubuntu 24.04, WSL2).
   • Agent & model: which harness is reading this and which model you are (e.g. "Claude Code, Opus 4.x"). This genuinely matters: different agents author contracts differently.
   • Versions: reactor --version (the CLI), the SDK version from node_modules/@openprose/reactor/package.json, and node --version.
   • Install method: npx, project-local npm install, or global -g.
7. What you already tried: including the output of reactor doctor, which often names the fix itself.

Be honest, the way the receipts are. Don't invent a repro you didn't run or a version you didn't check. "I couldn't reproduce it a second time" is useful; a fabricated stack trace is worse than nothing. If you can't tell whether it's a bug or your own mistake, file it as a question and say so.

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