cogno-persona

The prompt store for who a Cogno agent is. A light, infra-agnostic library that models an agent's declaration — the prompts that define its scope, execution behaviour, limits and voice, plus its identity, an opaque by-name binding to the modules it may use, and any tenant custom rules.

Persona = declaration ("who the agent is / may do"). It does not execute anything — allowed_modules is just names the host resolves into real tool dispatchers. Execution ("what it does") is a separate concern (cogno-praxis).

Distilled from the parent Cogno's core/prompt_loader.py + ego/persona*.py, with all the CoreDB / channel / env infra left to the host.

Why

The four prompt slots line up byte-for-byte with what the cogno-anima stages consume, so a host loads a persona and injects its prompts straight into the pipeline:

Install

pip install cogno-persona          # model + loader + store + selector + compose
pip install "cogno-persona[yaml]"  # + YAML frontmatter parsing in prompts

Five pieces

1. Persona — the typed container (pydantic)

from cogno_persona import Persona, PersonaPrompts

vet = Persona(
    persona_id="VETERINARY",
    description="pet health specialist",
    allowed_modules=["veterinary", "scheduler"],   # by-name binding (host resolves)
    custom_rules="Always confirm the pet's name first.",
    prompts=PersonaPrompts(system="You are the vet…", scope="…", limits="…", voice="…"),
)
vet.primary_module          # "veterinary"
vet.prompt("voice")         # the voice prompt text

2. loader — version-aware loading from disk

from cogno_persona import load_persona, load_prompt

vet = load_persona("personas/VETERINARY")           # manifest + slot files
vet = load_persona("personas/VETERINARY", version="v1")  # pin a prompt version
text = load_prompt("prompts", "voice.txt", stage="superego", version="v2")

A prompt may carry a sibling <name>_meta.json mapping version labels → files; list_versions / current_version introspect it.

3. store — the retrieval seam (homeo pattern)

from cogno_persona import FilePersonaStore, InMemoryPersonaStore, PersonaStore

store = FilePersonaStore("personas/")        # lazily loads each subdir
store = InMemoryPersonaStore([vet])          # for tests / seeding
# host implements PersonaStore over its own DB:  async get(id) / async list()

4. PersonaSelector — pick a specialist by embedding

from cogno_persona import PersonaSelector

selector = PersonaSelector(embedder, threshold=0.25)   # any cogno-synapse Embedder
result = await selector.select(
    noumeno.rewritten,                       # the canonical-English text (post-NOUMENO)
    candidates=await store.list(),
    base_persona_id="SECRETARY",
    intent_class=intent.intent_class,        # SOCIAL → base, no embedding
    restrict_to=identity.allowed_personas,   # N:N — compete only among allowed
)
result.persona_id, result.matched, result.score

Pure scoring (base penalty + inertia boost + threshold); the host owns candidate loading and embedding caches (pass candidate_vectors= to skip re-embedding). For a tenant with many similar personas, inject a reranker= (a Reranker Protocol — a host-provided cross-encoder) to reorder the above-threshold shortlist; it is off by default and unnecessary for small catalogs. See cognobench/ROUTING_BENCH_RESULTS.md.

5. compose — assemble the effective prompt

from cogno_persona import compose_prompt

system = compose_prompt(vet, "system", base=GLOBAL_RULES,
                        context={"tenant_name": "PetCo"})
# → base + persona.system + mandatory custom_rules block, {placeholders} filled

Pure assembly only — channel brevity, language pins, correction feedback and the like stay host concerns (append them yourself).

Design

See docs/HOST_INTEGRATION.md and LOGGING.md.

The Cogno ecosystem

cogno-persona is one organ of Cogno — a family of small, composable, Apache-2.0 libraries that together form a complete conversational-agent platform. Each library owns a single concern and stays infra-agnostic; a host assembles them into a running agent:

The open-source libraries are the organs; the host is the body that joins them. Our reference host — cogno-host, with its cogno-ui dashboard — is the private product layer, but it holds no special powers: everything it does rides on the public seams documented in each library's docs/HOST_INTEGRATION.md, so you can assemble a body of your own.

Development

pip install -e ".[dev]"
ruff check cogno_persona tests examples
mypy cogno_persona
pytest tests/unit -q --cov=cogno_persona

License

Apache-2.0