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An agent persona is a reusable template that defines an agent’s instructions, tools, model, and behavior. Use one to configure roles such as a code reviewer or an architect drafting a proposal. Personas live in the catalog as the agent-persona kind. They are tenant-scoped, version-controlled, and authored in Markdown with YAML frontmatter or as structured YAML.

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What a persona contains

Write the prompt like a senior engineer’s briefing. Include principles, conventions, and clear guidance on what to avoid or prefer.

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Follow-up instructions

When an event, such as a PR comment, PR review, or CI result, wakes an agent, the follow-up has two parts. The platform-formatted content contains the event facts, and the instructions say what to do. A persona can customize the instructions and checklist tasks for each event class through its followups map. For example, a payments reviewer can handle PR comments differently from a generalist while receiving the same event content. Personas shape the response, not the event formatting. See the agent-persona reference for the format.

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Built-in personas

Murmur ships platform-managed personas that exist in every tenant: Use them via the --agent flag on murmur spawn, or select them in the dashboard’s spawn dialog.

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Prototyper

Choose Prototyper in the Build category when you want a tight frontend feedback loop rather than a production-ready handoff. It uses the workspace’s fastest established preview path: for example, pushing a commit to refresh a build preview, or running a hot-reloading local app shared through Murmur’s port proxy. It asks early if the preview path or how you will access it is unclear. Prototyper prioritizes getting a working, current preview in front of you instead of waiting for full test suites, CI, routine reviews, or target-branch synchronization. It still fixes anything blocking that preview, respects workspace safety requirements, and reports checks deferred until you ask to finish or ship. To switch an existing agent into this mode, send a follow-up selecting the persona:
Prototyper sets disable_autopilot: true. On a supported agent, its first message turns autopilot off when the turn begins, whether you spawn a new agent or select Prototyper on a follow-up, through the CLI or dashboard. The message still runs. Later messages leave those settings unchanged, including when Prototyper remains selected in the dashboard; the action is not reapplied on each turn. Neither later messages nor changing personas automatically re-enable autopilot.

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Authoring your own

Create personas with murmur set agent-persona: either piping a Markdown file with YAML frontmatter, or structured YAML. Both produce identical catalog records. See the agent-persona reference for all fields and formats.

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Lifecycle

The agent inherits the persona’s tools, model, and system prompt at spawn time. You can select a different persona on a follow-up. Editing a persona does not automatically change a running agent’s configuration; future spawns and follow-ups that explicitly select the persona use its updated definition.