/Primitives
API referenceWebhooksKnowledge baseStartContextTopics & PlannerPhantomCMSCustom front endGet a keyBack to app

Primitives

Six primitives, one contract

Small, independent engines you can call alone or combine. Each has one door (app, API, MCP, CLI) and the same four parts.

  1. 1
    Constraints
    What can I configure?

    What a caller declares, as data: one config file per endpoint plus per-call options. One schema, read the same way whoever set it.

  2. 2
    Mechanism
    What always happens?

    What runs on every call no matter who asked. Enforced once, at the door, so an API key gets exactly what the app gets.

  3. 3
    Intelligence
    Who picks the values?

    You set them, or Letterstory derives them from your workspace. Both go through the same door.

  4. 4
    Verification
    Did it hold?

    After the run, each constraint is checked against the output and recorded. Failures are shown, never hidden.

The primitives

Kernels
Brief in, article out.

A brief, outline, notes or draft in; a finished article out, in the kernel's voice and passed by adversarial judges.

Shredders
Document in, the same document out, its prose rewritten.

Each paragraph is rewritten by a different model from a pool of providers, so no single model's mark survives. Structure, links, figures and quotes stay untouched.

Enhance
A written post in, the same post with links, citations, visuals and metadata.

Passes after the writer: internal links, citations, visuals and tables, and metadata. Each adds; none rewrites your prose.

Seers
A source to watch in, what's new and relevant out.

A seer watches a source and reports what's new and relevant, deduplicated and ready to become headlines or drafts.

Arenas
A topic in, a sourced, fact-checked outline out.

A research agent that gathers sources, weighs competing theses and fact-checks every claim. Each arena is one versioned file, like a kernel.

Collections
A standing publication in, published posts out, on a cadence.

The content engine as a primitive. A collection sources, writes, gates and publishes a post each run. A Phantomstory is a collection Letterstory hosts as its own publication.

Openers
A prospect in, a hand-approved cold-email opening line out.

Openers picks the best opening line for each prospect from a library of handwritten, human-approved lines. Nothing is generated: the model only chooses and fills placeholders that must pass a check.

What every primitive shares

  • An endpoint with one config file. Read it, replace it, version it. Per-call options win over its defaults, field by field.
  • Runs, not requests. Long work is asynchronous: submit, get a run_id back, poll until it settles. Openers, the one fast primitive, answers inline.
  • Every run records the request and its verification.
  • One capability pair per primitive on your API key (:read and :write), and its own balance.