refactor: eliminate integrity-level duplication, relocate truncateCacheKeyForLog, extract jsonutil package

[Copilot]

Three static-analysis findings where code lived in the wrong place or was independently redefined, creating silent drift risk and semantic confusion.

Finding 1 — Single source of truth for integrity levels

guard/wasm_validate.go hardcoded ["none","unapproved","approved","merged"] independently of the identical constants already in config. Adding a new level required three edits.

• Added config.AllIntegrityLevels() as the canonical exported accessor
• Kept the backing integrity-level list unexported in config and return a defensive copy to prevent mutation drift
• guard.AllowedIntegrityLevels now derives from config.AllIntegrityLevels()
• allowedGuardPolicyIntegrityLevels in config/guard_policy_validation.go now derives from config.AllIntegrityLevels()
• Added a test to confirm callers cannot mutate the canonical integrity-level list

// before
var AllowedIntegrityLevels = []string{"none", "unapproved", "approved", "merged"}

// after
var AllowedIntegrityLevels = config.AllIntegrityLevels()

Finding 2 — Move truncateCacheKeyForLog to its only call site

The function lived in http_helpers.go but was exclusively called from routed.go (3 call sites, all in cache eviction logging). Moved it there; removed the now-unused fmt and strings imports from http_helpers.go.

Finding 3 — Extract DeepCloneJSON from strutil

strutil is a string-formatting package; DeepCloneJSON operates on arbitrary interface{} values and doesn't belong there. Created internal/jsonutil package, moved the function and its tests, updated the one production caller (proxy/response_transform.go) and three proxy test files.

[Copilot]

Pull request overview

Refactors shared validation/utilities to reduce duplication and drift risk by centralizing integrity-level definitions, relocating a cache-key logging helper to its sole call site, and extracting JSON-cloning logic into a dedicated internal/jsonutil package.

Changes:

• Centralized integrity-level lists/constants via config.AllIntegrityLevels and updated guard/validation call sites.
• Moved truncateCacheKeyForLog from http_helpers.go to routed.go and cleaned up unused imports.
• Extracted DeepCloneJSON into internal/jsonutil, migrated its unit tests, and updated proxy code/tests to use the new package.

Show a summary per file

File	Description
internal/strutil/util.go	Removes DeepCloneJSON from strutil to keep the package focused on string helpers.
internal/strutil/util_test.go	Drops DeepCloneJSON unit tests now that cloning moved to jsonutil.
internal/server/routed.go	Adds truncateCacheKeyForLog at its only usage site (routed-mode cache logging).
internal/server/http_helpers.go	Removes now-unused truncateCacheKeyForLog and associated imports.
internal/proxy/response_transform.go	Switches deep-cloning to jsonutil.DeepCloneJSON.
internal/proxy/response_transform_test.go	Updates tests to reference jsonutil.DeepCloneJSON.
internal/proxy/response_transform_coverage_test.go	Updates coverage tests to reference jsonutil.DeepCloneJSON.
internal/proxy/proxy_test.go	Updates proxy tests to reference jsonutil.DeepCloneJSON.
internal/jsonutil/clone.go	Introduces jsonutil.DeepCloneJSON in a semantically appropriate package.
internal/jsonutil/clone_test.go	Adds unit tests for jsonutil.DeepCloneJSON.
internal/guard/wasm_validate.go	Replaces hardcoded integrity strings with config-derived values.
internal/config/guard_policy.go	Adds AllIntegrityLevels as a central integrity-level list.
internal/config/guard_policy_validation.go	Aliases allowed integrity-levels to AllIntegrityLevels for validation.

Copilot's findings

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• Files reviewed: 13/13 changed files
• Comments generated: 2

[lpcox]

@copilot address review feedback

[Copilot]

@copilot address review feedback

Addressed in commit ff68c5b.

• Replaced exported mutable integrity-level slice with config.AllIntegrityLevels() accessor that returns a defensive copy.
• Updated guard/config call sites to consume the accessor, removing local redefinition drift risk.
• Added a test to verify callers cannot mutate the canonical integrity-level list.