Model HTTP hook handler type

[bguidolim]

Phase 2: HTTP Hook Handler Type

Context

Claude Code now supports type: "http" hook handlers that send the event's JSON input as an HTTP POST to a URL. The endpoint returns decisions using the same JSON output format as command hooks.

New Fields

Field	Type	Description
type	"http"	Handler type
url	String	URL to POST to
headers	[String: String]?	HTTP headers with env var interpolation ($VAR_NAME / ${VAR_NAME})
allowedEnvVars	[String]?	Env var names permitted for header interpolation

Example

{
  "type": "http",
  "url": "http://localhost:8080/hooks/pre-tool-use",
  "timeout": 30,
  "headers": {
    "Authorization": "Bearer $MY_TOKEN"
  },
  "allowedEnvVars": ["MY_TOKEN"]
}

Files to Modify

• Sources/mcs/Core/Settings.swift — extend HookEntry to support url, headers, allowedEnvVars
• Sources/mcs/ExternalPack/ExternalPackManifest.swift — allow packs to define HTTP hooks
• Validation: if type == "http", url is required
• Tests for serialization/round-tripping

Acceptance Criteria

• HookEntry can represent HTTP hooks with all fields
• Pack authors can define HTTP hooks in techpack.yaml
• Validation ensures url is present for HTTP type
• Backward compatible

Reference

• Hooks reference — HTTP hook fields