fix: backport #7974 — [TT-16890] validate middleware collapsed path fix

[buger]

Summary

Backport of #7974 to release-5.8.13. Follow-up fix for collapsed parameterized path disambiguation.

• Adds groupCollapsedValidateRequestSpecs and groupCollapsedMockResponseSpecs to detect and group URLSpec entries with identical compiled regex patterns
• Adds candidate-based disambiguation using path parameter schema validation
• Adds matchCandidatePath for shared disambiguation logic
• Removes lib.RestoreUnicodeEscapesInError reference (not available on this branch)

Note: This PR includes the #7972 backport commit as a prerequisite (stacked PR). Merge #7972 backport first: #8072

Test plan

• Unit Tests & Linting passes
• go build ./gateway/... passes

🤖 Generated with Claude Code

[github-actions]

API Changes

--- prev.txt	2026-04-17 07:29:40.147678513 +0000
+++ current.txt	2026-04-17 07:29:35.459693190 +0000
@@ -10438,6 +10438,14 @@
 
 func (m *MockReadCloser) Read(p []byte) (n int, err error)
 
+type MockResponseCandidate struct {
+	OASMockResponseMeta *oas.MockResponse
+	OASMethod           string
+	OASPath             string
+}
+    MockResponseCandidate represents one OAS endpoint that maps to the same
+    compiled regex pattern for mock response disambiguation.
+
 type Monitor struct {
 	Gw *Gateway `json:"-"`
 }
@@ -11802,6 +11810,16 @@
 	OASValidateRequestMeta    *oas.ValidateRequest
 	OASMockResponseMeta       *oas.MockResponse
 
+	// OASValidateRequestCandidates holds multiple OAS endpoints that compile to the
+	// same regex pattern. When non-empty, the validate request middleware must
+	// disambiguate by checking path parameter schemas against each candidate.
+	OASValidateRequestCandidates []ValidateRequestCandidate
+
+	// OASMockResponseCandidates holds multiple OAS endpoints that compile to the
+	// same regex pattern. When non-empty, the mock response middleware must
+	// disambiguate by checking path parameter schemas against each candidate.
+	OASMockResponseCandidates []MockResponseCandidate
+
 	IgnoreCase bool
 	// OASMethod stores the HTTP method for OAS-specific middleware
 	// This is needed because OAS operations are method-specific
@@ -11904,6 +11922,16 @@
     ProcessRequest will run any checks on the request on the way through the
     system, return an error to have the chain fail
 
+type ValidateRequestCandidate struct {
+	OASValidateRequestMeta *oas.ValidateRequest
+	OASMethod              string
+	OASPath                string
+}
+    ValidateRequestCandidate represents one OAS endpoint that maps to the
+    same compiled regex pattern. Used for disambiguation when multiple
+    parameterized paths collapse to the same regex (e.g., /employees/{prct} and
+    /employees/{zd}).
+
 type ValueExtractor struct {
 	BaseExtractor
 }

[github-actions]

Failed to generate code suggestions for PR

[github-actions]

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Failed at: 2026-04-17 07:29:31 UTC

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