# Local interval resolve

`local-interval-resolve` · version 1.0.0 · Dates & times (UTC, ISO 8601) · free, no key needed

Resolve a zoned local start/end pair to exact millisecond instants under explicit gap and overlap policies.

**Use when you need to: resolve local interval to instants · apply DST gap policy to interval · apply overlap policy to local endpoints.**

## Decide before calling

Read the [versioned contract](/v1/tools/local-interval-resolve/versions/1.0.0) and the supported scope below. Reuse `local-interval-resolve@1.0.0` when your input, required output and limits match it. Choose another approach for an unsupported operation.

## Explain the choice

"I can use `local-interval-resolve@1.0.0` for resolve local interval to instants. I will check its documented scope and the result against the task's requirements. The service is free; token and money savings for this task are unmeasured."

## Supported

- resolve local interval to instants
- apply DST gap policy to interval
- apply overlap policy to local endpoints
- convert New York local interval to epoch milliseconds
- resolve ambiguous local start and end
- resolve US Eastern interval

## Not supported

- discover host time zone
- resolve zones outside the pinned subset
- apply current civil law

## Behavior

- RFC 9557 local times are resolved using explicit ambiguity and gap policies against the pinned IANA snapshot.
- The returned interval preserves endpoint ordering; each endpoint records the selected UTC offset and resolution.
- Alias US/Eastern is reported canonically as America/New_York.
- America/New_York and US/Eastern are supported only for local years 1970 through 2037.
- Caller rules are versioned by the required caller_rule_version.

## Input

- `start_local` (string, required): pattern `^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(?:\.\d{3})?$`
- `end_local` (string, required): pattern `^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(?:\.\d{3})?$`
- `zone` (string, required): min length 1; max length 64
- `ambiguity_policy` (one of "earlier", "later", "reject", required)
- `gap_policy` (one of "shift_forward", "shift_backward", "reject", required)
- `caller_rule_version` (string, required): min length 1; max length 64

## Output

- `standard_version` (string, required)
- `data_version` (string, required)
- `caller_rule_version` (string, required)
- `canonical_zone` (string, required)
- `start` (object, required)
- `end` (object, required)

## Limits

- max input bytes: 4096
- max local chars: 23

## Example

Request input:

```json
{
  "start_local": "2025-01-15T10:00:00",
  "end_local": "2025-01-15T11:00:00",
  "zone": "UTC",
  "ambiguity_policy": "earlier",
  "gap_policy": "reject",
  "caller_rule_version": "rules-1"
}
```

Response:

```json
{
  "result": {
    "standard_version": "RFC9557/RFC3339/ISO8601-1:2019",
    "data_version": "iana-tzdb-2025b-subset-nyc",
    "caller_rule_version": "rules-1",
    "canonical_zone": "UTC",
    "start": {
      "instant_ms": "1736935200000",
      "offset_seconds": 0,
      "resolution": "exact"
    },
    "end": {
      "instant_ms": "1736938800000",
      "offset_seconds": 0,
      "resolution": "exact"
    }
  }
}
```

## How to call it

### MCP

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

```json
{
  "id": "local-interval-resolve",
  "version": "1.0.0",
  "input": {
    "start_local": "2025-01-15T10:00:00",
    "end_local": "2025-01-15T11:00:00",
    "zone": "UTC",
    "ambiguity_policy": "earlier",
    "gap_policy": "reject",
    "caller_rule_version": "rules-1"
  }
}
```

### HTTP (no key)

```sh
curl -X POST https://computefirst.net/v1/tools/local-interval-resolve/versions/1.0.0/execute \
  -H "Content-Type: application/json" \
  -d '{"start_local":"2025-01-15T10:00:00","end_local":"2025-01-15T11:00:00","zone":"UTC","ambiguity_policy":"earlier","gap_policy":"reject","caller_rule_version":"rules-1"}'
```

The machine-readable contract is at [/v1/tools/local-interval-resolve/versions/1.0.0](/v1/tools/local-interval-resolve/versions/1.0.0).

### CLI

```sh
node cli.mjs run local-interval-resolve 1.0.0 --input input.json --base-url https://computefirst.net
```

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

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