---
title: "Which sequencing reads actually tell your candidates apart"
method: POST
path: "/read_placement_plan"
tags: ["Primers & oligos"]
---

# Which sequencing reads actually tell your candidates apart

`POST /read_placement_plan`

## Request

- Base URL: `https://seqbench.com/api/v1`
- URL: `https://seqbench.com/api/v1/read_placement_plan`
- Auth: none required

Given the molecules a cloning reaction could have produced and the sequencing primers you could use, work out which primers separate which pairs of candidates — and return the smallest set that separates every pair any of them can. Scores a read by discrimination, not coverage: a read of 700 bases every candidate shares is worth nothing, and a short read across a junction is worth everything. Names the pairs no primer here separates, so you find out before paying for the reads rather than after. Pair it with outcome_deconvolve once the traces come back.

## Request body

- object
  - `candidates` object[], required: The molecules this reaction could produce, as { id, label, sequence, circular? }. Between 2 and 24; assembly_outcomes' intended plus alternatives is the intended source.
  - `primers` object[], required: Sequencing primers to choose between, as { id, label, sequence }. Up to 32.
  - `usableFrom` number: Bases after the primer's 3' end before the trace becomes readable (0-500). A difference inside this dead zone is not counted as a separation, because the trace cannot show it.
  - `usableLength` number: Readable bases per reaction, counted from usableFrom (50-5000).
  - `maxMismatches` integer: Mismatch budget passed to the priming scan. Defaults to primer-binding's own (~10% of the primer's length).

## Response `200`

Tool ran successfully.

- SuccessResponse: Standard success envelope returned by every single-tool call.
  - `ok` unknown, required
  - `tool` string, required: The tool slug that ran.
  - `result` object, required: Tool-specific output object. Its shape depends on the tool — call `GET /{tool}` or see the docs for each tool's fields.
  - `gate` GateResult
    - `pass` boolean, required: True if and only if every hard check passed.
    - `checks` GateCheck[], required
      - `id` string, required
      - `label` string, required
      - `severity` 'hard' | 'soft', required
      - `pass` boolean, required
      - `message` string, required
      - `value` number
      - `threshold` string
    - `notChecked` string[], required: Honest list of what this gate does NOT verify.
  - `provenance` Provenance, required
    - `apiVersion` string, required
    - `tool` union, required: Tool slug, or an array of slugs (one per step) for a workflow.
      - string
      - string[]
    - `generatedAt` string, date-time, required: ISO 8601 timestamp of when the result was generated.

## Other responses

- `400`: Invalid argument or the tool could not run.
- `404`: Unknown tool.
- `429`: Rate limited (metered tools only). Body carries code `rate_limited` and retryable `true`; honor the Retry-After header.
- `503`: A metered tool is momentarily at capacity. The identical request should succeed after Retry-After; body carries code `upstream_unavailable`.

---

[API](https://skmtc.dev/seqbench/apis/seqbench-api.md) · [All operations](https://skmtc.dev/seqbench/apis/seqbench-api/llms.txt) · [OpenAPI document](https://skmtc.dev/seqbench/apis/seqbench-api/revisions/132575216865?raw)