Murmur

Murmur

Objection-finding for pricing and launch changes. Rehearse the arguments before you ship — powered by the coding subscription you already pay for.

Murmur is an MCP server that rehearses community reaction to a pricing, launch, policy, or crisis decision: seed it with your material (a pricing page, a policy memo, an incident brief), and a population of simulated personas debates it across Twitter-style and Reddit-style platforms. You get a ranked objection dossier — each objection at its strongest, tied to the simulated post behind it, with a counter-case and a test plan for real humans — plus the ability to interview any simulated persona about why they wrote what they wrote. It is a structured set of arguments, not a validated forecast; simulated personas are invented critics, not your customers.

Zero API keys. Zero extra bills. The engine is deterministic and LLM-free; every generation is performed by your coding agent's LLM (Claude, Codex, Gemini, Antigravity, OpenCode, Hermes…) through the connection you already have. The server ships no network code — enforced by the build gate (static scans of bundle + engine source, plus an obfuscation scan) and a runtime probe that executes the engine adapters with fetch stubbed to throw and fails if fetch is ever called.

You:            /murmur-predict How will r/programming react to the new pricing page?
Your agent:     world_init → seed_add → ontology(plan/submit)                → graph(build) → personas(plan/submit)                → [sim(next_batch/submit)] × 8 rounds                → report(plan/submit/export)
Result:         .murmur/reports/pricing-reaction/report-1.md                (Mermaid sentiment charts, cited risks, post index, diffable)

Why

Tools like MiroFish solve social simulation with a server-side LLM: you pay a monthly plan, supply an API key, and your data goes through their cloud. Murmur flips the architecture — Host-Powered Inference:

The engine (world state, ontology graph, persona activation, feed ranking, retweet amplification, vote gravity, virality, sentiment, stance migration, escalation detection, statistics) is pure, deterministic computation. The intelligence — writing posts in character, drafting the report narrative, answering interviews — is borrowed from the host agent in batched plan/submit exchanges, so one tool call amortizes many generations.

Install

One command per client (Node ≥ 20):

The npx -y murmur-mcp commands above assume the package is on the registry. The murmur-mcp npm name is not claimed yet, so npx fails today — until the first publish, use the from-source path in the next note.

Every snippet is also printed by npx murmur-mcp doctor (which also checks Node, the SQLite native module and your workspace) and npx murmur-mcp init --client <id>. init --client <id> --write only writes a config file for cursor, vscode, opencode and windsurf; for every other client (Claude Code included) it prints the snippet and asks you to merge it into client.configPath yourself.

Installing from source (before the first npm publish): npm install in the monorepo, then run node packages/server/dist/index.js directly (or npm link inside packages/server for a global murmur-mcp command). Release artifacts ship via npm with provenance once the repo is live (npm i -g murmur-mcp).

Quickstart

1. Install for your client (above).
2. Put some material in your repo — a pricing page export, a FAQ, a changelog, or run npx murmur-mcp init --template launch for a fill-in brief.
3. In your coding agent:

/murmur-predict How will developers react to our new pricing? Sources: pricing-page.md, FAQ.md

That prompt is a playbook: your agent drives all 12 tools in order, shows you digests for approval, writes the report, and every receipt tells it the next step.

What a run actually costs. Zero keys, but not zero time: a default 8-round world puts the order of hundreds of generations in front of your host model, so wall time is set by the model and the batch size, not by Murmur. Nothing has been published end-to-end with a real LLM yet — the 651-test suite (golden byte-identical replays plus the cleanroom release gate) runs against mock generations, and npm run demo exercises the full pipeline headless. Treat your first real run as a rehearsal, and start with fewer rounds.

Mid-run experimentation:

/murmur-simulate How will r/programming react to the pricing change? Rounds: 4  … agent pauses, shows you the sentiment timeline …  You: inject "competitor undercuts us by 30%" and continue/murmur-interview Ask @ada why she's so hostile about the migration guide/murmur-resume pricing-reaction

What you get

• .murmur/murmur.db — the whole world in SQLite (10 tables: worlds, seeds, entities, relations, personas, memories, posts, events, reports, generations). Portable by copying the directory; resumable at any stage boundary after a crash.
• .murmur/{world}/graph.mmd — the ontology graph as Mermaid (typed relations: alliance / opposition / influence / ownership, with tension scores).
• .murmur/reports/{world}/report-N.md — versioned scenario reports: Mermaid xychart sentiment curves, stance-migration bars, escalation chains, persona leaderboards, deterministic statistics appendix and a post index. Reports regenerate, never mutate — diff two scenarios line by line.
• .murmur/reports/{world}/report-N.html — the same report as a self-contained dashboard (report_export with format: "md" | "html" | "both"): inline CSS + SVG charts (sentiment lines, faction donut, platform-divergence bars, trajectory projection), KPI cards, quote banks, risk register — zero JavaScript, zero external requests, safe to commit or share. It shares one engine computation with the .md, so the two can never disagree on a number.
• .murmur/{world}/interviews.jsonl + qa.jsonl — logged deep-interaction dialogues.
• .murmur/{world}/audit.jsonl — the audit trail of every plan/submit exchange.

How it works

The five-stage pipeline (full parity with the category, reimagined for agents):

1. Seeds — attach files (PDF/MD/TXT/CSV/JSON), URLs (your agent fetches, the engine never does), or pasted text. Byte-hashed dedupe.
2. Ontology — ontology_plan composes an extraction task (seed digests + strict JSON schema); your agent's LLM extracts entities, motives and factual anchors; ontology_submit validates item-by-item with surgical retry.
3. Graph — deterministic derivation of typed relations and tensions; reddit-style communities; stance-affinity follow graph; Mermaid export.
4. Population — archetype distribution derived from the ontology; Big-Five-lite traits; per-entity stances; platform mix; audit and edit individuals before the run.
5. Simulation — each round the engine activates a weighted persona subset and composes personalized digests (persona card ≤ 120 tokens, ranked feed, working memory, collective view); your LLM writes their posts/replies/votes; the engine ingests, runs platform mechanics (feed ranking, retweet amplification, vote gravity, virality thresholds), organic engagement, three-tier memory with compaction, stance migration and sentiment tracking. Inject god's-eye events between rounds and watch the trajectory move.
6. Report + interaction — deterministic stats + evidence pack in, narrative out, versioned report to disk; then interview any persona (grounded in its own memory and posts — it declines knowledge it never saw) or interrogate the whole run with cited answers.

Context-budget engineering is an engine contract, not a hope: persona cards are capped, feeds are ranked-and-truncated per persona, memory compacts between rounds, no tool response exceeds 12,000 tokens (oversize payloads spill to disk with fetch-by-id receipts), and batch sizes adapt via world_config.

Determinism: content ids are count-based, all randomness flows from the world seed through named streams, and phases 2–5 of every round are pure functions of stored state. Golden-run tests replay recorded sessions and assert byte-identical outcomes.

Tool catalog (12 tools)

Every pre-consolidation name (the old 29-tool surface) still has a row in MIGRATED_TOOLS (packages/server/src/tools/index.ts), so receipts and error messages teach the new spelling of any old name you type.

Prompts (one-command playbooks): murmur-predict, murmur-simulate, murmur-interview, murmur-resume. Resources: murmur://worlds, murmur://world/{id}/state, murmur://world/{id}/report/{rid}.

Configuration

// defaults (tune via world_config / sim_configure){  "rounds": 8,                                  // 1–40  "batch":  { "maxPersonas": 20, "maxFeedItems": 8, "personaCardTokens": 120 },  "context": { "maxResponseTokens": 12000 },  "engagement": { "viralityThreshold": 8, "organicCapPerPost": 0.6 },  "memory": { "episodicMaxRecords": 40 }}

Environment: MURMUR_WORKSPACE (override the workspace root; default: git repo root), MURMUR_LOG (stderr log level; stdout is protocol-only).

Guarantees (tested, not promised)

• No API key, ever — no key or token field exists in any config surface; the cleanroom gate statically fails the release on egress APIs, URLs, or key patterns in the shipped bundle, and audits the dependency closure for network libraries.
• Client neutrality — the server contains zero client-specific branches; per-client differences live in packages/adapters as snippets and templates.
• Resumability — every tool is safe to re-issue after a crash; sessions resume to the exact stage boundary.
• Performance — engine-side wall time is 1.48s at the 24×8 defaults and 2.98s at the 48×8 flagship scale (report render included, host-LLM latency excluded; node tools/scale-benchmark.mjs <personas> <rounds> to reproduce); a 24-persona, 8-round world completes in a single agent session.

Repository layout

packages/  engine/      deterministic simulation core (pure TS + SQLite adapter)  server/      the murmur-mcp npm package: 12 tools, resources, prompts, CLI  prompts/     playbook prompt packs  adapters/    per-client install snippets + config templates (10 clients)  templates/   scenario packs: launch, policy, crisis, finance, fictiontests/  golden/      byte-identical replay tests + pipeline acceptance (F1–F7)  integration/ real MCP client ↔ server e2e over stdio  cleanroom/   the release gate (no-egress, no-key, deps, timing, isolation)examples/      a ready-to-run demo scenario + paste-ready prompts

Develop: npm install && npm run build && npm test (651 tests) · npm run test:e2e · npm run cleanroom · npm run demo (headless full pipeline, no LLM needed).

License & provenance

Apache-2.0. Murmur is a clean-room implementation: no code, prompts or configuration from any AGPL-licensed project were copied (see CONTRIBUTING.md for the policy that binds every contribution). "MiroFish" is a third-party trademark used only in factual comparisons.