refactor: extract shared httputil, remove trivial wrappers in mcp and cmd

[Copilot]

Three categories of dead indirection identified across internal/: one exact cross-package duplicate, one private wrapper delegating to the public function three lines below it, and one exported wrapper used only within its own package.

Changes

internal/httputil (new package)

• Extracts WriteJSONResponse — previously copy-pasted byte-for-byte in both server/http_helpers.go and proxy/handler.go
• server keeps a package-local shim for internal callers; proxy call-sites updated directly

// internal/httputil/httputil.go
func WriteJSONResponse(w http.ResponseWriter, statusCode int, body interface{}) {
    w.Header().Set("Content-Type", "application/json")
    w.WriteHeader(statusCode)
    json.NewEncoder(w).Encode(body)
}

internal/mcp/connection.go

• Removes getAgentTagsSnapshotFromContext — a one-liner wrapping GetAgentTagsSnapshotFromContext with no added value
• Single call-site on line 374 updated to call the exported function directly

internal/cmd/flags_difc.go

• Removes exported ValidateDIFCMode — never called outside cmd, was a one-liner over difc.ParseEnforcementMode
• Both call-sites (root.go, proxy.go) inlined to difc.ParseEnforcementMode; proxy.go gains the difc import
• Tests updated to call difc.ParseEnforcementMode directly

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• example.com
  • Triggering command: /tmp/go-build502407326/b336/launcher.test /tmp/go-build502407326/b336/launcher.test -test.testlogfile=/tmp/go-build502407326/b336/testlog.txt -test.paniconexit0 -test.timeout=10m0s /tmp/go-build502407326/b252/vet.cfg 64/src/runtime/cgo main x_amd64/vet (dns block)
• invalid-host-that-does-not-exist-12345.com
  • Triggering command: /tmp/go-build502407326/b320/config.test /tmp/go-build502407326/b320/config.test -test.testlogfile=/tmp/go-build502407326/b320/testlog.txt -test.paniconexit0 -test.timeout=10m0s 64/s�� go edprintable/reader.go x_amd64/compile (dns block)
• nonexistent.local
  • Triggering command: /tmp/go-build502407326/b336/launcher.test /tmp/go-build502407326/b336/launcher.test -test.testlogfile=/tmp/go-build502407326/b336/testlog.txt -test.paniconexit0 -test.timeout=10m0s /tmp/go-build502407326/b252/vet.cfg 64/src/runtime/cgo main x_amd64/vet (dns block)
• slow.example.com
  • Triggering command: /tmp/go-build502407326/b336/launcher.test /tmp/go-build502407326/b336/launcher.test -test.testlogfile=/tmp/go-build502407326/b336/testlog.txt -test.paniconexit0 -test.timeout=10m0s /tmp/go-build502407326/b252/vet.cfg 64/src/runtime/cgo main x_amd64/vet (dns block)
• this-host-does-not-exist-12345.com
  • Triggering command: /tmp/go-build502407326/b345/mcp.test /tmp/go-build502407326/b345/mcp.test -test.testlogfile=/tmp/go-build502407326/b345/testlog.txt -test.paniconexit0 -test.timeout=10m0s --no�� _.a (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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[Copilot]

Pull request overview

Refactors internal packages to remove dead indirection and consolidate duplicated HTTP/JSON response logic, reducing maintenance overhead across server/proxy/cmd/mcp.

Changes:

• Introduces internal/httputil.WriteJSONResponse and updates server/proxy to use it (server keeps a local shim).
• Removes trivial wrapper getAgentTagsSnapshotFromContext in internal/mcp.
• Removes unused exported ValidateDIFCMode wrapper in internal/cmd and updates call sites/tests to use difc.ParseEnforcementMode.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
internal/server/http_helpers.go	Replaces duplicated JSON response writer implementation with a shim calling internal/httputil.
internal/proxy/handler.go	Switches JSON responses to httputil.WriteJSONResponse and removes local helper.
internal/mcp/connection.go	Drops redundant private wrapper and calls exported context helper directly.
internal/httputil/httputil.go	Adds shared JSON response writer helper for HTTP-facing packages.
internal/cmd/root.go	Inlines DIFC mode validation via difc.ParseEnforcementMode.
internal/cmd/proxy.go	Inlines DIFC mode validation and adds difc import.
internal/cmd/flags_difc_test.go	Updates tests to validate modes via difc.ParseEnforcementMode.
internal/cmd/flags_difc.go	Removes unused exported ValidateDIFCMode wrapper.

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[Copilot]

This test now validates difc.ParseEnforcementMode directly, but the test function name still references the removed ValidateDIFCMode helper. Renaming the test (and any related descriptions) will keep intent clear and avoid confusion when searching for ValidateDIFCMode usages.