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 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:

{
  "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:

{
  "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), then call execute with:

{
  "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)

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.

CLI

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

Get the client at /clients/cli/.

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