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.

Unit: Arena
A run produces: an outline with its sources, direction, stat ledger and paper trail
In the app: /arenas
API reference: All arenas tools

Try it

run_arena over REST: POST /api/arena/ingest/{arena_id}. Needs an API key with arena:write.

curl -X POST https://app.letterstory.com/api/arena/ingest/<arena_id> \
  -H "x-integrations-key: ls_..." \
  -H "content-type: application/json" \
  -d '{
  "template": {},
  "depth": "...",
  "direction_gate": false,
  "provider": "...",
  "verify": false,
  "unresolved_claims": "...",
  "mention_degree": "...",
  "context": {},
  "blocked_mentions": [],
  "blocked_domains": [],
  "preferred_sources": [],
  "topic": "...",
  "source_urls": [],
  "must_include": [],
  "shape": {},
  "direction": "...",
  "existing_content": "...",
  "article_id": "...",
  "target_word_count": 0
}'

1. Constraints: what you configure

The arena's own file (one JSON file per version)

namemodeldepthproviderdirectionGateverifyunresolvedClaimsmentionDegreecontextblockedtemplateruleseffortadvanced

Only name is required; the rest uses platform settings, and every save is a new, unchangeable version. model is the research model; rules sets each source-policy call to enforce, measure or off. Use ours, copy it, or bring your own.

The endpoint's config file

namedefaults.depthdefaults.direction_gatedefaults.providerdefaults.verifydefaults.contextdefaults.template

Per call

topicsource_urlsmust_includedepthdirection_gateproviderverifyblocked_mentionsblocked_domainspreferred_sourcesshape

provider is native, exa, youcom or context-dev. Anything you leave undeclared inherits your organization's settings.

2. Mechanism: what always happens

1Gather from the live web, then read the page behind every citation, with one extra gather per named subject the outline turns up.
2Pick a direction: an agent chooses the thesis, or, with the direction gate on, proposes three and pauses for you.
3Synthesize against a stat ledger: only figures actually found in the sources may be stated precisely. Blocked names are scrubbed.
4Fact-check every claim against the sources and the web. A failing phase is marked failed with its reason, and the run carries on.

3. Intelligence: who picks values

You, directly

An API key or the Studio controls everything. Letterstory decides nothing.

Letterstory, for you

Auto-Pen, the planner and the phantom orchestrator supply the post's title, a seer's source URLs, the template's sections, the collection's depth and its preferred sources.

4. Verification: did it hold

Check	Reads back	Rule
`sourced`	`mechanism`	At least one source has a real page behind it.
`read`	`mechanism`	At least one page was read.
`grounded`	`mechanism`	Every stated figure is tied to a source.
`direction`	`direction_gate`	A thesis was decided.
`shape`	`shape`	Every required section is planned.
`fact_checked`	`verify`	The verify phase completed.

Report-only; an unfinished run reads back as skipped on all six.

Surfaces

Same call over MCP (tools/call) and REST.

Job	MCP tool	REST
Run	`run_arena`	`POST /api/arena/ingest/{arena_id}`
Poll a run	`get_arena_run`	`GET /api/arena/ingest/{arena_id}/runs/{run_id}`
	`list_arena_runs`	`POST /api/integrations/tools/list_arena_runs`
Steer	`submit_arena_direction`	`POST /api/arena/ingest/{arena_id}/runs/{run_id}/direction`
	`cancel_arena_run`	`POST /api/arena/ingest/{arena_id}/runs/{run_id}/cancel`
Arenas	`list_arenas`	`POST /api/integrations/tools/list_arenas`
	`create_arena`	`POST /api/integrations/tools/create_arena`
	`delete_arena`	`POST /api/integrations/tools/delete_arena`
Arena config	`get_arena_config`	`POST /api/integrations/tools/get_arena_config`
	`set_arena_config`	`POST /api/integrations/tools/set_arena_config`
The arena file	`get_arena_file`	`POST /api/integrations/tools/get_arena_file`
	`save_arena_file`	`POST /api/integrations/tools/save_arena_file`
	`promote_arena_version`	`POST /api/integrations/tools/promote_arena_version`
	`list_arena_versions`	`POST /api/integrations/tools/list_arena_versions`
	`pin_arena_version`	`POST /api/integrations/tools/pin_arena_version`
	`accept_arena_offer`	`POST /api/integrations/tools/accept_arena_offer`
Balance	`get_arena_run_balance`	`POST /api/integrations/tools/get_arena_run_balance`

CLI: letterstory arena run --topic …

Direct runs draw arena run credits; errored and cancelled runs are free. Runs Auto-Pen makes for you are not billed.

Other primitives

Kernels Shredders Enhance Seers Collections Openers