Change API Key Prefix from `sk_` to `jikan_`

[thunderrabbit]

Proposal: Change API Key Prefix from sk_ to jikan_

Problem

Currently, generated API keys use the sk_ prefix (inherited from Stripe conventions). This is confusing because:

• Jikan is a distinct product with its own identity
• The sk_ prefix signals "Stripe key" to anyone reading logs or documentation
• It's unclear at a glance that the key is scoped to Jikan/mg.robnugen.com

Solution

Change API key generation to use jikan_ prefix instead.

Rationale

• Clarity: Immediately obvious that the key is for Jikan, not a payment service
• Branding: Aligns with naming conventions in other MCP/AI tool ecosystems
• Developer Experience: Makes key scope obvious in logs, env vars, and documentation

Scope

Backend Changes (mg.robnugen.com)

• Update key generation logic to prefix new keys with jikan_ instead of sk_
• Likely location: wwwroot/settings/ API key generation endpoint or classes/ auth logic
• Decide on migration strategy for existing sk_ keys:
  • Option A: Support both sk_ and jikan_ indefinitely
  • Option B: Deprecation timeline (e.g., "support until 2026-07-01")
  • Option C: Automatic rotation (regenerate existing keys)

Documentation Updates (jikan repo)

• Update README.md examples to reference jikan_ keys
• Update claude_desktop_config.json example
• Update any other references to sk_your_key_here

Testing

• Verify new keys are generated with jikan_ prefix
• Verify existing sk_ keys still work (if keeping backward compatibility)
• Update tests in mg.robnugen.com and jikan repos

Acceptance Criteria

• New API keys generated on /settings/ use jikan_ prefix
• Jikan README and examples reference jikan_ keys
• Backward compatibility decision documented (support both? deprecate?)
• Existing keys continue to work (or migration path clear)
• Tests updated and passing

See also:

API key generation in mg.robnugen.com