Compare the base API, not to_s, when refreshing a mounted app

[ericproulx]

Problem

refresh_already_mounted deduplicates endpoints for the "same" mounted app with a string compare:

endpoints.delete_if { |endpoint| endpoint.mounted_app.to_s == app.to_s }

This only works by accident. mount turns every mounted Grape API into a throwaway mount_instance, and mount_instance builds a fresh Class.new(@base_parent) on every call (lib/grape/api.rb), so two mounts of the same API are distinct objects — app == mounted_app is always false. What makes the .to_s compare land is that Grape::API::Instance delegates to_s to its @base (the original API):

def_delegators :@base, :to_s   # lib/grape/api/instance.rb

So mounted_app.to_s == app.to_s is really asking "do these two throwaway instances share the same base API?" — through a string proxy. That's brittle: it's an identity check dressed up as a string compare, and two distinct APIs that happen to share a name (same to_s) falsely dedup.

Fix

Compare the base API by identity — the real signal the string proxy stands in for. @base was writer-only (base=), so this exposes a reader and compares it:

def same_mounted_app?(mounted, app)
  return mounted.base.equal?(app.base) if mounted.respond_to?(:base) && app.respond_to?(:base)

  mounted.equal?(app)
end

Plain Rack apps have no base and are mounted as-is (same object across mounts), so they fall back to object identity.

Tests

• Existing refresh_already_mounted specs still pass (same API → same base → deduped; no flag → duplicated).
• Added a spec that forces a #to_s collision between two distinct APIs and asserts the refresh keys off base identity, not the string — it fails on the old to_s compare (removes the wrong endpoint) and passes with this change.
• Full suite: 2352 examples, 0 failures; RuboCop clean.

🤖 Generated with Claude Code

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