# Graph ancestors

`graph-ancestors` · version 1.0.0 · Graphs & scheduling · free, no key needed

List every ancestor of given targets, including the targets, in reverse-graph BFS discovery order.

**Use when you need to: graph ancestors · upstream prerequisites of targets · ancestors of graph nodes.**

## Supported

- graph ancestors
- upstream prerequisites of targets
- ancestors of graph nodes

## Not supported

- dominance
- immediate parents only
- undirected ancestor search
- enumerating every ancestor path

## Behavior

- Input is a directed simple graph plus a non-empty targets array of unique existing node ids.
- An original edge from u to v means u is a prerequisite of v and a reverse-graph successor of v.
- The output nodes array is reverse-graph BFS discovery order, including every target.
- Targets are enqueued in the given targets array order, skipping an id already queued.
- After a node is popped, unseen reverse-graph neighbors are pushed in the declared order of original incoming edges.
- A target is included even when it has no incoming edges.
- Empty graph cannot name a target and is rejected.
- Self-loops and directed cycles are allowed; first visit wins.
- Unknown fields, duplicate nodes or edges, missing endpoints, and unknown or duplicate targets are rejected.

## Input

- `nodes` (array of string, required): max items 2000; each min length 1; each max length 256
- `edges` (array of object, required): max items 10000
- `targets` (array of string, required): min items 1; max items 2000; each min length 1; each max length 256

## Output

- `nodes` (array of string, required)

## Limits

- max nodes: 2000
- max edges: 10000
- max node id bytes: 256
- max targets: 2000

## Example

Request input:

```json
{
  "nodes": [
    "compile",
    "test",
    "lint",
    "package",
    "deploy"
  ],
  "edges": [
    {
      "from": "compile",
      "to": "test"
    },
    {
      "from": "compile",
      "to": "package"
    },
    {
      "from": "lint",
      "to": "package"
    },
    {
      "from": "test",
      "to": "deploy"
    },
    {
      "from": "package",
      "to": "deploy"
    }
  ],
  "targets": [
    "deploy"
  ]
}
```

Response:

```json
{
  "result": {
    "nodes": [
      "deploy",
      "test",
      "package",
      "compile",
      "lint"
    ]
  }
}
```

## How to call it

### MCP

Connect `https://computefirst.net/mcp` ([setup](/docs#connect)), then call `execute` with:

```json
{
  "id": "graph-ancestors",
  "version": "1.0.0",
  "input": {
    "nodes": [
      "compile",
      "test",
      "lint",
      "package",
      "deploy"
    ],
    "edges": [
      {
        "from": "compile",
        "to": "test"
      },
      {
        "from": "compile",
        "to": "package"
      },
      {
        "from": "lint",
        "to": "package"
      },
      {
        "from": "test",
        "to": "deploy"
      },
      {
        "from": "package",
        "to": "deploy"
      }
    ],
    "targets": [
      "deploy"
    ]
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/graph-ancestors/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"nodes":["compile","test","lint","package","deploy"],"edges":[{"from":"compile","to":"test"},{"from":"compile","to":"package"},{"from":"lint","to":"package"},{"from":"test","to":"deploy"},{"from":"package","to":"deploy"}],"targets":["deploy"]}'
```

The machine-readable contract is at [/v1/tools/graph-ancestors/versions/1.0.0](/v1/tools/graph-ancestors/versions/1.0.0).

### CLI

```sh
node cli.mjs run graph-ancestors 1.0.0 --input input.json --base-url https://computefirst.net
```

Get the client at [/clients/cli/](/clients/cli/).

## Related tools

- [Graph dependency impact](/tools/graph-dependency-impact): List nodes downstream of a removed set: not themselves removed, reachable by a directed path of length at least 1.
- [Graph induced subgraph](/tools/graph-induced-subgraph): Return the vertex-induced subgraph on a listed node subset, preserving declared node and edge order.
- [Graph reachable from](/tools/graph-reachable-from): List nodes reachable from given sources by directed BFS, in discovery order.
- [Graph shortest unweighted path](/tools/graph-shortest-unweighted-path): Find a shortest directed path by fewest edges from source to target.
- [Graph validate](/tools/graph-validate): Inspect a well-formed directed simple graph and report counts, isolated nodes, and maximum degrees.
- [Graph connected components](/tools/graph-connected-components): Partition a directed simple graph into undirected connected components, ignoring edge direction.