Extract BaseResponseWriter to httputil to eliminate duplicate status-capture code

[Copilot]

internal/server/response_writer.go and internal/tracing/http.go each independently implemented an http.ResponseWriter wrapper with identical WriteHeader/Write/Unwrap status-capture logic — and had already diverged (implicit-200 handling present in tracing but absent in server).

Changes

• internal/httputil/response_writer.go — new BaseResponseWriter embedding http.ResponseWriter with:

  • WriteHeader: captures status code and forwards
  • Write: captures implicit 200 on first write if no prior WriteHeader
  • Unwrap: exposes underlying writer for http.ResponseController interface delegation (http.Flusher, etc.)

• internal/tracing/http.go — statusResponseWriter now just embeds httputil.BaseResponseWriter; its own WriteHeader, Write, and Unwrap implementations removed (all promoted from base)

• internal/server/response_writer.go — responseWriter embeds httputil.BaseResponseWriter instead of raw http.ResponseWriter; retains its own WriteHeader/Write only for logging and body-capture, delegating the status logic to the base type

// Before: duplicated across two packages
type statusResponseWriter struct {
    http.ResponseWriter
    statusCode int
}
func (rw *statusResponseWriter) WriteHeader(code int) { rw.statusCode = code; rw.ResponseWriter.WriteHeader(code) }
func (rw *statusResponseWriter) Write(b []byte) (int, error) { /* implicit-200 logic */ }
func (rw *statusResponseWriter) Unwrap() http.ResponseWriter { return rw.ResponseWriter }

// After: single definition in httputil, embedded where needed
type statusResponseWriter struct {
    httputil.BaseResponseWriter
}

• internal/httputil/response_writer_test.go — full test coverage for BaseResponseWriter
• internal/tracing/http_test.go — updated to use promoted StatusCode field

[Copilot]

Pull request overview

This PR centralizes HTTP status-code capture logic by introducing a shared httputil.BaseResponseWriter and reusing it from both tracing and server response-writer wrappers, eliminating duplicated (and previously diverged) implementations.

Changes:

• Added internal/httputil/BaseResponseWriter to capture status codes (including implicit 200) and support http.ResponseController via Unwrap.
• Refactored tracing’s statusResponseWriter to embed the shared base wrapper and updated call sites/tests accordingly.
• Updated the server responseWriter to embed the shared base wrapper while retaining body capture + logging.

Show a summary per file

File	Description
internal/httputil/response_writer.go	Introduces shared BaseResponseWriter implementation for status capture + Unwrap.
internal/httputil/response_writer_test.go	Adds unit tests for the new base response-writer behavior.
internal/tracing/http.go	Refactors tracing response-writer wrapper to embed the shared base type.
internal/tracing/http_test.go	Updates tests to validate status capture via the promoted StatusCode field.
internal/server/response_writer.go	Updates server response-writer to embed BaseResponseWriter and delegate status logic while keeping body buffering/logging.

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• Files reviewed: 5/5 changed files
• Comments generated: 2

[lpcox]

@copilot address review feedback

[Copilot]

@copilot address review feedback

Fixed in the latest commit. BaseResponseWriter now tracks a private wroteHeader flag:

• WriteHeader: only captures StatusCode on the first call; subsequent calls are forwarded to the underlying writer without mutating the captured status.
• Write: sets wroteHeader = true alongside the implicit-200 capture, so a later WriteHeader can no longer overwrite it.

Two new tests cover both scenarios (TestBaseResponseWriter_WriteHeader_FirstCallWins and TestBaseResponseWriter_Write_LaterWriteHeaderDoesNotOverrideImplicit200).