How to generate a capsule manifest with mur new

Beta feature

mur new "<task description>" is a beta feature: it exists only in a mur built with the beta-mur-new feature, and runs only after mur beta enable mur-new. Behavior and flags may change in future releases. To scaffold a formation instead, use mur new --roster, which is in every build.

mur new takes a plain-language task description and writes a ready-to-refine murmur.yaml to the current directory. It cold-boots a short-lived generator capsule backed by your inference provider, which queries the artifact index to discover relevant tools and produces a manifest tailored to the task — no schema knowledge required.

The relevant manifest options are:

Option	Controls
lifecycle.task_acceptance	How the capsule accepts tasks; always single in generated manifests
lifecycle.after_task	What happens after the task completes; always exit in generated manifests
inference.model	The model the generated capsule will use; the generator chooses it, so check it

---

Step 1 — install the generator artifacts

mur new runs its generator capsule from four artifacts, which must be in the global store ~/.murmur/artifacts/ before the first run. Install them with mur install -g; a project install does not reach the generator.

AnthropicOpenAI

mur install -g murmur/driver-anthropic@0.19.0
mur install -g murmur/tool-registry-search@0.5.0
mur install -g murmur/tool-editor@0.12.0
mur install -g murmur/skill-create-manifest@0.12.0

mur install -g murmur/driver-openai@0.19.0
mur install -g murmur/tool-registry-search@0.5.0
mur install -g murmur/tool-editor@0.12.0
mur install -g murmur/skill-create-manifest@0.12.0

Different ways to install artifacts

mur install fetches an artifact from the source of its scope. murmur/ artifacts come from the built-in source, murmur-nexus/default-artifacts, with no configuration.

Option A — name the source of a scope in ~/.murmur/config.yaml:

registry:
  sources:
    - repo: <owner>/<repo>
      token: "${GITHUB_TOKEN}"

Then install by full name, with or without a version:

mur install <owner>/<artifact-name>@<version>

Option B — pass a full GitHub reference and skip configuration entirely:

mur install github:<owner>/<repo>@<tag>

See Installing artifacts to learn more.

mur new checks for these artifacts before starting any capsule. If one is missing it exits with E-RUN-008 and the mur install -g command that installs it.

Configure your inference provider — mur new detects it automatically using the following priority order:

1. Config file (~/.murmur/config.yaml, inference: section) — recommended for repeated use:

   inference:
     provider: anthropic          # or "openai"
     model: claude-haiku-4-5-20251001
     api_key: sk-ant-...
     endpoint: ""                 # leave empty to use the provider default
   

2. Environment variable — ANTHROPIC_API_KEY (model claude-haiku-4-5-20251001) or OPENAI_API_KEY (model gpt-5.6-luna). When detected, mur new prints a one-line hint suggesting you add inference: to ~/.murmur/config.yaml instead.

3. First-run wizard — if neither the config file nor an env var is present, mur new launches an interactive wizard that prompts for provider, model, and API key, then offers to save the result to ~/.murmur/config.yaml for future runs.

The wizard requires an interactive terminal. In non-interactive contexts (CI, piped stdin), it exits with error E-CFG-001 and a message describing how to configure inference.

---

Step 2 — run mur new

Run mur new with a plain-language description of what the capsule should do:

mur new "review this PR for security issues"

Output:

mur new: generating manifest...
murmur.yaml written to /path/to/current-dir/murmur.yaml

The generator queries the artifact index, reasons about the task, and writes murmur.yaml to the current directory.

By default the generator searches the index on the latest default-artifacts release. To point it at another source's index, pass the index's URL:

mur new "review this PR for security issues" \
  --index https://github.com/your-org/your-artifacts/releases/latest/download/artifacts-index.json

The generator capsule fetches that URL itself, and mur new adds its host to the generator's network allow list. The same index decides the versions of the generator's driver, tools and skill: the newest of each that fits your mur, which is what to have installed. To search an index file on disk, pass its path instead; mur new checks it and copies it into the generator's work folder:

mur new "review this PR for security issues" --index ./artifacts-index.json

The generator cannot see the artifacts installed on this machine, so --index local is refused with E-NEW-005. To list what is installed, run:

mur search "" --index local

---

Step 3 — understand the output

The generator picks one of two shapes based on the task description.

Single capsule — for focused, bounded tasks (review, classify, summarise):

AnthropicOpenAIDeepSeek

name: pr-security-reviewer
version: "0.1.0"

artifacts:
  - name: murmur/driver-anthropic
    version: "0.19.0"
    runtime: driver
    gateway:
      endpoint: https://api.anthropic.com
      api_key: ${ANTHROPIC_API_KEY}
  - name: murmur/tool-git
    version: "0.6.0"
    runtime: tool

capabilities:
  shell:
    allow:
      - git

lifecycle:
  task_acceptance: single
  after_task: exit

inference:
  model: claude-sonnet-5
  driver:
    artifact: murmur/driver-anthropic

name: pr-security-reviewer
version: "0.1.0"

artifacts:
  - name: murmur/driver-openai
    version: "0.19.0"
    runtime: driver
    gateway:
      endpoint: https://api.openai.com/v1
      api_key: ${OPENAI_API_KEY}
  - name: murmur/tool-git
    version: "0.6.0"
    runtime: tool

capabilities:
  shell:
    allow:
      - git

lifecycle:
  task_acceptance: single
  after_task: exit

inference:
  model: o3-mini-high
  driver:
    artifact: murmur/driver-openai

name: pr-security-reviewer
version: "0.1.0"

artifacts:
  - name: murmur/driver-deepseek
    version: "0.17.0"
    runtime: driver
    gateway:
      endpoint: https://api.deepseek.com
      api_key: ${DEEPSEEK_API_KEY}
  - name: murmur/tool-git
    version: "0.6.0"
    runtime: tool

capabilities:
  shell:
    allow:
      - git

lifecycle:
  task_acceptance: single
  after_task: exit

inference:
  model: deepseek-r1
  driver:
    artifact: murmur/driver-deepseek

Orchestrator — for research, multi-step, pipeline, or report tasks. The generator adds a spawn block so the capsule can launch child capsules:

AnthropicOpenAIDeepSeek

name: climate-research-agent
version: "0.1.0"

artifacts:
  - name: murmur/driver-anthropic
    version: "0.19.0"
    runtime: driver
    gateway:
      endpoint: https://api.anthropic.com
      api_key: ${ANTHROPIC_API_KEY}

capabilities:
  spawn:
    allow:
      - local/climate-data-worker

lifecycle:
  task_acceptance: single
  after_task: exit

inference:
  model: claude-sonnet-5
  driver:
    artifact: murmur/driver-anthropic

name: climate-research-agent
version: "0.1.0"

artifacts:
  - name: murmur/driver-openai
    version: "0.19.0"
    runtime: driver
    gateway:
      endpoint: https://api.openai.com/v1
      api_key: ${OPENAI_API_KEY}

capabilities:
  spawn:
    allow:
      - local/climate-data-worker

lifecycle:
  task_acceptance: single
  after_task: exit

inference:
  model: o3-mini-high
  driver:
    artifact: murmur/driver-openai

name: climate-research-agent
version: "0.1.0"

artifacts:
  - name: murmur/driver-deepseek
    version: "0.17.0"
    runtime: driver
    gateway:
      endpoint: https://api.deepseek.com
      api_key: ${DEEPSEEK_API_KEY}

capabilities:
  spawn:
    allow:
      - local/climate-data-worker

lifecycle:
  task_acceptance: single
  after_task: exit

inference:
  model: deepseek-r1
  driver:
    artifact: murmur/driver-deepseek

Generated manifests are a starting point

Artifact versions in the generated manifest reflect what the generator found in the artifact index at run time. mur install refuses a version that does not fit this mur and names the one that does; run mur list to compare with what is installed.

---

Step 4 — refine the manifest

Open murmur.yaml and check these fields before running:

Model — the generator chooses inference.model. Change it if the task needs a different model:

AnthropicOpenAIDeepSeek

inference:
  model: claude-sonnet-5

inference:
  model: o3-mini-high

inference:
  model: deepseek-r1

System prompt — the generator does not add inference.system_prompt. Add one to give the capsule role-specific context:

inference:
  system_prompt: |
    You are a security-focused code reviewer. Focus on OWASP Top 10 vulnerabilities,
    insecure defaults, and missing input validation.

Capabilities — add or remove capabilities.network.allow entries to match what the capsule actually needs to access. Remove entries for hosts the capsule will never contact.

---

Step 5 — install manifest dependencies

mur install

Different ways to install artifacts

mur install fetches an artifact from the source of its scope. murmur/ artifacts come from the built-in source, murmur-nexus/default-artifacts, with no configuration.

Option A — name the source of a scope in ~/.murmur/config.yaml:

registry:
  sources:
    - repo: <owner>/<repo>
      token: "${GITHUB_TOKEN}"

Then install by full name, with or without a version:

mur install <owner>/<artifact-name>@<version>

Option B — pass a full GitHub reference and skip configuration entirely:

mur install github:<owner>/<repo>@<tag>

See Installing artifacts to learn more.

---

Step 6 — run the capsule

Create a task.md file with the task description for the capsule, then run it:

mur run --manifest murmur.yaml --task task.md

---

Summary

Feature / setting	How it works
mur new "<description>"	Boots a generator capsule; writes murmur.yaml to CWD
No --index	Searches the index on the latest default-artifacts release
--index <url>	Searches that index; its host is added to the generator's network allow list
--index <path>	Checks the index file on the host, then searches a copy in the generator's work folder
--index local	Refused with E-NEW-005; mur search <query> --index local lists the installed artifacts
Single capsule	Generated for focused, bounded tasks — no spawn block
Orchestrator	Generated for research and pipeline tasks — adds a capabilities.spawn.allow list
Validation	Generated YAML is validated before writing; nothing written if validation fails
Inference config	Config file (inference: in ~/.murmur/config.yaml) → env var (ANTHROPIC_API_KEY / OPENAI_API_KEY) → interactive first-run wizard
Generator artifacts	murmur/driver-anthropic (or murmur/driver-openai), murmur/tool-registry-search, murmur/tool-editor and murmur/skill-create-manifest must all be in the global store; install them with mur install -g
Artifact discovery	murmur/tool-registry-search is a native tool and runs in the generator capsule's sandbox; What each native tool needs lists what it can reach
inference.model	Chosen by the generator; change it in the generated manifest if needed

---

See also

• mur search — search the artifact index from the CLI
• murmur/tool-registry-search — the in-capsule tool the generator uses for artifact discovery
• murmur/skill-create-manifest — full schema reference skill for authoring manifests manually
• mur build — build the generated capsule into a .mur.zip
• mur run — run the capsule locally