Issue 538.7: Plain Text Content Negotiation for Audit API

[ngjunsiang]

Summary

Add plain text content negotiation support for campus.audit API endpoints.

Background

Parent issue: #538
The original API key requirements (#541) mentioned supporting both JSON and plain text content types, but only JSON is currently implemented.

Requirements

1. Support text/plain Content-Type

For endpoints that return single resources or simple messages, support plain text responses:

Create endpoint (POST /audit/v1/apikeys):

• Accept: application/json → Return JSON with key details
• Accept: text/plain → Return plaintext key value only

List endpoint (GET /audit/v1/apikeys):

• Accept: application/json → Return JSON array
• Accept: text/plain → Return formatted text list (one per line)

Get endpoint (GET /audit/v1/apikeys/<id>):

• Accept: application/json → Return JSON object
• Accept: text/plain → Return formatted key details

2. Content Negotiation

Use Flask's request.accept_mimetypes to determine response format:

from flask import request

if request.accept_mimetypes.accept_json:
    return json_response, 200
elif 'text/plain' in request.accept_mimetypes:
    return plain_text_response, 200, {'Content-Type': 'text/plain'}
else:
    return json_response, 200  # Default to JSON

3. Plain Text Formats

Define simple, human-readable formats:

• Create: Just the key value on its own line
• List: One key per line with format: name:owner_id:scopes
• Get: Multi-line format with key details
• Delete: Simple "OK" or "Revoked" message

Acceptance Criteria

• All API key endpoints support text/plain Accept header
• Plain text responses are properly formatted
• Content negotiation defaults to JSON for /
• Tests for both JSON and plain text responses
• Documentation of plain text formats

Related

• Parent: campus.audit: API Key Security Implementation #538
• Endpoints: Issue 538.3: API Key Management Endpoints #541