lead.executable

A lead.executable event describes a two-leg purchase that, because of a proven relation between two markets, pays at least $1 per pair in every outcome, and that could be filled at a profit when both order books were read. The body is the LeadEvent schema in the API reference; this page explains each field and walks through the numbers of one delivery. Slack subscriptions receive a text rendering instead (see the overview).

Example delivery

POST /routeur HTTP/1.1
Host: hooks.example.com
Content-Type: application/json
User-Agent: Routeur-Webhooks/1
Routeur-Delivery: 48213
Routeur-Signature: t=1790532613,v1=3e0fef4bac5524301d9f37cca1382b3d0312fe1681347ae3d31a0e9f0dabb0ce

{
  "type": "lead.executable",
  "version": "2026-09-15",
  "created_at": "2026-09-27T18:10:13Z",
  "graph_run": 4812,
  "lead": {
    "relation": "equivalent",
    "cross_venue": true,
    "left": {
      "venue": "kalshi",
      "id": "KXNFLGAME-26SEP27KCLV-KC",
      "title": "Kansas City at Las Vegas winner?"
    },
    "right": {
      "venue": "polymarket",
      "id": "nfl-kc-lv-2026-09-27-kc",
      "title": "Chiefs vs. Raiders: Chiefs win"
    },
    "legs": [
      { "venue": "kalshi", "market_id": "KXNFLGAME-26SEP27KCLV-KC", "side": "no", "ask_usd": "0.30" },
      { "venue": "polymarket", "market_id": "nfl-kc-lv-2026-09-27-kc", "side": "yes", "ask_usd": "0.64" }
    ],
    "depth": {
      "pairs": "60",
      "cost_usd": "56.4",
      "fees_usd": "0.89",
      "net_usd": "2.71",
      "limited_by": "depth",
      "executable": true,
      "observed_at": "2026-09-27T18:10:12Z",
      "issues": [
        "estimated: kalshi KXNFLGAME-26SEP27KCLV-KC no fee is the series rate × contracts × p × (1 − p), rounded up to the cent per leg"
      ]
    },
    "caveats": [
      "estimated: kalshi KXNFLGAME-26SEP27KCLV-KC no fee is the series rate × contracts × p × (1 − p), rounded up to the cent per leg",
      "unverified: top-of-book depth is unknown; asks are discovery observations",
      "estimated: Kalshi standard 0.07 taker fee for one contract; series fee multipliers and rounding across quantities are not applied",
      "unverified: the covering payout assumes the event settles normally; postponement, cancellation and disputes settle differently across venues"
    ]
  }
}

The body is shown formatted; the delivered bytes are compact and their key order is not guaranteed. Signatures are computed over the bytes as sent (see Verifying signatures, which uses this same event).

Fields

All fields are always present. Amounts are exact decimal strings (Decimal in the reference), never floats; timestamps are RFC 3339 in UTC.

Envelope

Field	Type	Meaning
`type`	`"lead.executable"`	Branch on this; a `ping` uses the same headers.
`version`	string	The body’s shape version, currently `2026-09-15`. A new version means fields were added, renamed or removed; the same version never changes shape.
`created_at`	timestamp	When the graph run that found the lead finished. Retries keep the original value.
`graph_run`	integer	The graph run id. `GET /v1/status` reports the latest run; `GET /v1/opportunities` responses carry the run they were read from.
`lead`	object	The lead itself, below.

`lead`

Field	Type	Meaning
`relation`	`equivalent`, `subset`, `superset` or `contradicts`	The proven relation, stated from `left`’s side: `subset` means left Yes implies right Yes; `superset` the reverse; `contradicts` means at most one can settle Yes. `overlaps` relations are never leads.
`cross_venue`	boolean	`true` when the two legs are on different venues.
`left`, `right`	object	The two markets: `venue` (`kalshi` or `polymarket`), `id` (the venue’s market id: a Kalshi ticker or a Polymarket market slug) and `title`. Fetch either with `GET /v1/markets/{venue}/{id}`.
`legs`	array of 2	What to buy, in order `[left, right]`. Each has `venue`, `market_id`, `side` (`yes` or `no`) and `ask_usd`, the top-of-book ask observed by the crawl the graph run read, per contract.
`depth`	object	The lead sized against both live order books, below.
`caveats`	array of strings	`depth.issues` followed by the caveats of the top-of-book estimate. See Issues and caveats.

Which sides cover which relation is fixed:

`relation`	`legs[0].side` (left)	`legs[1].side` (right)	Why it pays $1
`subset`	`no`	`yes`	Left Yes implies right Yes, so left No or right Yes always holds.
`superset`	`yes`	`no`	The mirror image.
`contradicts`	`no`	`no`	At most one settles Yes, so at least one No pays.
`equivalent`	`yes` / `no`	`no` / `yes`	Either pairing; exactly one leg pays.

`lead.depth`

Walks both books’ asks, taking quantity while each additional pair, with both legs’ taker fees, still costs less than the $1 it pays. Whole contracts and each venue’s order minimum are then applied.

Field	Type	Meaning
`executable`	boolean	Always `true` in a webhook; only executable leads are delivered.
`pairs`	decimal	How many pairs (one contract of each leg) can be bought profitably. Kalshi legs are whole contracts; Polymarket legs can be fractional shares.
`cost_usd`	decimal	Principal across both legs for `pairs`, walking each ladder past the top of book. It can exceed `pairs × (legs[0].ask_usd + legs[1].ask_usd)`.
`fees_usd`	decimal	Taker fees for the fill: Kalshi’s series rate × contracts × p × (1 − p), rounded up to the cent per leg; Polymarket’s market rate × shares × p × (1 − p), or zero for fee-free markets.
`net_usd`	decimal	`pairs − cost_usd − fees_usd`: the profit if every level filled as observed. This is what `min_net` filters on.
`limited_by`	string	What stopped the size from growing. See below.
`observed_at`	timestamp	When the older of the two books was read. Both are read within seconds of each other; a larger gap is reported as a `stale:` issue.
`issues`	array of strings	Notes from reading the books and sizing the fill. Never `null` in a webhook.

`limited_by` values

Value	Meaning	In a webhook?
`depth`	One leg’s book ran out of asks below the payout.	Yes
`price`	The next pair would cost at least $1 with fees.	Yes
`minimum`	The profitable size is below a whole contract or a venue’s order minimum.	No: not executable.
`fees`	Fee rounding consumed the edge.	No: not executable.
`unavailable`	A leg’s book could not be read, or the market is not in the run.	No: not executable.
`informational`	The pair would fill, but the relation rests on a settlement the venues could resolve differently (economic releases that are delayed or cancelled). Reported by the API only; never offered as executable.	No: never delivered.

Issues and caveats

Every string starts with a category:

Prefix	Meaning	Where it appears
`estimated:`	A fee was estimated from the venue’s schedule; the venue’s rounding may differ.	`depth.issues` (fill fees), `caveats` (top-of-book fees).
`unverified:`	Something was assumed: unknown fee counted as zero, top-of-book depth unknown, cross-venue settlement assumed normal, or legs settling in different currencies.	`depth.issues`, `caveats`.
`stale:`	Legs were observed too far apart to be treated as simultaneous: more than 10 seconds between book reads, or more than a minute between crawl asks.	`depth.issues`, `caveats`.
`only … of a pair is available below the payout; whole contracts are required` / `profitable size is below the minimum order for …`	Sizing stopped at a minimum. Accompanies `limited_by: minimum`, so not in a webhook.	`depth.issues`
`informational:`	Marks an informational lead. Not in a webhook.	`caveats`

caveats always contains unverified: top-of-book depth is unknown; asks are discovery observations. It describes the legs[].ask_usd estimate, which depth supersedes; read depth for the sizing and the caveats for what was assumed.

Worked example

Taking the delivery above:

Relation. Kalshi’s “Kansas City at Las Vegas winner?” is proven equivalent to Polymarket’s “Chiefs win”, so buying No on Kalshi and Yes on Polymarket pays exactly $1 per pair whichever team wins.
Top of book. At the crawl, the asks were 30¢ and 64¢: 94¢ for a guaranteed $1.
Depth. Walking both books, 60 pairs could be bought before Kalshi’s No side ran out (limited_by: depth). The principal for 60 pairs was $56.40; the Kalshi leg's taker fee at the series rate came to $0.89 after rounding up to the cent, and the Polymarket market charges no fee.
Net. 60 − 56.40 − 0.89 = 2.71. With the subscription’s default min_net of 1, the lead was delivered.
Caveats. The fee is estimated, and the cross-venue caveat applies: if the game is postponed or cancelled, the two venues may settle differently, and the pair is no longer guaranteed.

The books were read at 18:10:12 UTC and the event created a second later; by the time you act, the asks may have moved. Re-read both books before ordering.

Handling advice

Acknowledge with 2xx before doing anything slow; Routeur waits 10 seconds in total.
Deduplicate on Routeur-Delivery; the same lead can also legitimately arrive again after six hours or when its net doubles, with a new delivery id and a new graph_run.
Treat net_usd as the ceiling for the whole size, not a per-contract figure.
Compare version with the one you built against and log anything else rather than failing.

Webhooks overview: what fires, filters, retries.
Verifying signatures: a worked signature over this exact body.
Leads and Relations: how leads are derived from proven relations.
Cross-venue: what settles differently across venues.

Get started

Concepts

Agents & MCP

Webhooks

Reference

lead.executable

Example delivery

Fields

Envelope

`lead`

`lead.depth`

`limited_by` values

Issues and caveats

Worked example

Handling advice

Example delivery

Fields

Envelope

lead

lead.depth

limited_by values

Issues and caveats

Worked example

Handling advice

Related

`lead`

`lead.depth`

`limited_by` values