reuse-surface/specs/FederationHubAPI.md

Federation Hub API

Repository: reuse-surface
Artifact: specs/FederationHubAPI.md
Status: Draft 0.1 (REUSE-WP-0011-T01)
Schema: schemas/hub-registration.schema.yaml

---

1. Purpose

The federation hub is a hosted coordination service that records which repositories publish capability indexes and serves a composed federated index for agent discovery. It does not store capability entry Markdown bodies.

Companion deployment workplan: railiance-apps RAILIANCE-WP-0007.

---

2. Base URL and formats

Item	Value
Default production URL	https://reuse-hub.whywhynot.de (confirm at deploy)
API prefix	/v1
Read formats	JSON (default), YAML via Accept: application/yaml or ?format=yaml
Write content type	application/json

Environment variables for clients:

Variable	Purpose
REUSE_SURFACE_HUB_URL	Hub base URL (no trailing slash)
REUSE_SURFACE_HUB_TOKEN	Bearer token for write operations

---

3. Authentication

Endpoint class	Auth
GET /health, GET /v1/repos, GET /v1/repos/{repo}, GET /v1/federated	Public (read)
POST /v1/repos, PATCH /v1/repos/{repo}, DELETE /v1/repos/{repo}, POST /v1/federated/compose	Bearer token required

Write requests must include:

Authorization: Bearer <REUSE_SURFACE_HUB_TOKEN>

Missing or invalid token → 401 Unauthorized.

---

4. Registration model

A registration mirrors federation url sources from schemas/federation.schema.yaml, plus hub metadata:

Field	Required	Notes
repo	yes	Slug [a-z][a-z0-9-]*; primary key
url	yes	HTTP(S) URL to capabilities.yaml
enabled	yes	Include in federated compose when true
domain	yes	e.g. helix_forge
required	no	Fail compose if fetch fails and no cache
description	no	Human-readable note
cache_ttl_seconds	no	Default 86400
auth_env	no	Hub container env var for fetch auth (never returned in GET)
auth_header	no	Default Authorization
registered_at	hub	ISO-8601 UTC
updated_at	hub	ISO-8601 UTC
registered_by	no	Optional client-supplied actor label

Local filesystem index paths are not accepted — registrations must use published raw URLs.

---

5. Endpoints

5.1 GET /health

Liveness/readiness probe.

Response 200:

{
  "status": "ok",
  "service": "reuse-surface-hub",
  "version": "0.1.0"
}

5.2 GET /v1/repos

List all registrations (including disabled).

Response 200:

{
  "count": 2,
  "repos": [
    {
      "repo": "reuse-surface",
      "url": "https://gitea.coulomb.social/coulomb/reuse-surface/raw/main/registry/indexes/capabilities.yaml",
      "enabled": true,
      "required": true,
      "domain": "helix_forge",
      "description": "Primary registry",
      "cache_ttl_seconds": 86400,
      "registered_at": "2026-06-15T12:00:00Z",
      "updated_at": "2026-06-15T12:00:00Z"
    }
  ]
}

auth_env is omitted from responses.

5.3 POST /v1/repos

Register a new repository. Auth required.

Request body: registration_request from schema.

Response 201: Full registration object.

Errors:

Code	Condition
400	Schema validation failure
401	Missing/invalid token
409	repo already registered

5.4 GET /v1/repos/{repo}

Fetch one registration.

Response 200: Registration object.
Response 404: Unknown repo.

5.5 PATCH /v1/repos/{repo}

Update fields on an existing registration. Auth required.

Request body: registration_update from schema (at least one field).

Response 200: Updated registration.

Errors: 400, 401, 404.

5.6 DELETE /v1/repos/{repo}

Remove a registration. Auth required.

Response 204: No content.
Response 404: Unknown repo.

5.7 GET /v1/federated

Return the composed federated index from all enabled registrations.

Reuses WP-0010 remote fetch/cache logic server-side. Output shape matches registry/indexes/federated.yaml:

version: 1
updated: "2026-06-15"
domain: helix_forge
collision_policy: warn
sources:
  - repo: reuse-surface
    url: https://...
    count: 12
capabilities:
  - id: capability.registry.register
    source_repo: reuse-surface
    source_url: https://...
    # ... index fields ...

Query parameters:

Param	Default	Meaning
format	json	json or yaml
refresh	false	Bypass remote cache when true

Warnings from compose (duplicate IDs, fetch fallbacks) are returned in response header X-Federation-Warnings (semicolon-separated) for MVP; JSON envelope extension is a future option.

Response 200: Federated index document.
Response 502: Required source unavailable with no cache.

5.8 POST /v1/federated/compose

Trigger federated index refresh (same as GET /v1/federated?refresh=true). Auth required. Useful for operators after bulk registration changes.

Response 200: Federated index document.

---

6. Error envelope

Non-2xx responses use:

{
  "error": "validation_error",
  "message": "Human-readable summary",
  "details": ["optional field-level messages"]
}

error code	HTTP
validation_error	400
unauthorized	401
not_found	404
conflict	409
compose_error	502

---

7. Hub service configuration

Env var	Required	Purpose
REUSE_SURFACE_HUB_TOKEN	yes	Write API bearer token
REUSE_SURFACE_HUB_DB	no	SQLite path (default /data/hub.db)
REUSE_SURFACE_HUB_CACHE_DIR	no	Remote index cache (default /data/cache)
REUSE_SURFACE_HUB_DOMAIN	no	Default federated domain (default helix_forge)

---

8. CLI mapping

CLI command	API call
reuse-surface hub status	GET /health
reuse-surface hub list	GET /v1/repos
reuse-surface hub show --repo X	GET /v1/repos/X
reuse-surface hub register ...	POST /v1/repos
reuse-surface hub update ...	PATCH /v1/repos/{repo}

Global flags: --hub-url, env REUSE_SURFACE_HUB_URL, REUSE_SURFACE_HUB_TOKEN.

---

9. Deployment reference

• Image: gitea.coulomb.social/coulomb/reuse-surface-hub:<tag>
• Probe path: /health
• Persistence: PVC at /data (SQLite + fetch cache)
• Helm release: railiance-apps RAILIANCE-WP-0007