fix(tracing): semconv v1.27.0→v1.34.0, fix mcp.tool_call attribute misuse, add server.address

[Copilot]

Addresses several OTel correctness and best-practice issues identified in the go-fan module review: a semantic attribute mismatch on an internal span, manual gen_ai key definitions that duplicated official semconv, and minor span hygiene gaps.

Semconv upgrade (v1.27.0 → v1.34.0)

Updated the import alias in all four files that reference semconv. v1.34.0 is bundled with the already-pinned go.opentelemetry.io/otel@v1.43.0 — no module version bump required.

genai_attrs.go: replace manual constants with official semconv aliases

The five gen_ai.* keys were hand-rolled strings. They're now aliases to the official semconv/v1.34.0 constants, eliminating drift risk. Call sites are unchanged — the alias type is identical (attribute.Key).

// Before
GenAIToolName = attribute.Key("gen_ai.tool.name")

// After
GenAIToolName = semconv.GenAIToolNameKey  // "gen_ai.tool.name" — official semconv/v1.34.0

Added MCPResponseStatus = attribute.Key("mcp.response.status") for the conceptual HTTP status on internal MCP spans.

unified.go: fix semantic mismatch on mcp.tool_call span

mcp.tool_call is SpanKindInternal — setting http.response.status_code on it violates the OTel spec (that attribute is reserved for HTTP client/server spans). Replaced with the new mcp.response.status key.

// Before — semantically wrong on an internal span
toolSpan.SetAttributes(semconv.HTTPResponseStatusCodeKey.Int(httpStatusCode))

// After
toolSpan.SetAttributes(tracing.MCPResponseStatus.Int(httpStatusCode))

proxy/handler.go: span hygiene

• Added semconv.ServerAddressKey (upstream hostname) to the proxy.backend.forward span for upstream visibility in trace backends. Extracted via a new Server.upstreamHost() helper.
• Switched fwdSpan.End() to defer fwdSpan.End() to prevent span leaks if early-return paths are introduced by future refactors.

[Copilot]

Pull request overview

This PR updates the gateway’s OpenTelemetry instrumentation to align with newer semantic conventions (semconv v1.34.0) and fixes attribute usage on non-HTTP/internal spans, while improving proxy forwarding span metadata for upstream visibility.

Changes:

• Upgraded semconv imports from v1.27.0 to v1.34.0 across tracing/proxy code.
• Replaced hand-rolled gen_ai.* attribute keys with official semconv constants and introduced mcp.response.status for internal MCP spans.
• Improved proxy forwarding span lifecycle handling and added server.address attribution for upstream tracing.

Show a summary per file

File	Description
internal/tracing/provider.go	Bumps semconv import to v1.34.0 for provider/resource attributes.
internal/tracing/provider_test.go	Updates tests to match semconv v1.34.0 import.
internal/tracing/http.go	Updates HTTP span wrapper to semconv v1.34.0 import.
internal/tracing/genai_attrs.go	Re-exports official gen_ai keys and adds mcp.response.status.
internal/server/unified.go	Stops using HTTP status semconv on an internal span; uses mcp.response.status instead.
internal/proxy/proxy.go	Adds Server.upstreamHost() helper for server.address attribution.
internal/proxy/handler.go	Adds server.address to forward span and defers span end for safety.

Copilot's findings

Tip

Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

• Files reviewed: 7/7 changed files
• Comments generated: 2

[lpcox]

@copilot fix this failing ci checks https://github.com/github/gh-aw-mcpg/actions/runs/26638527237/job/78504913214?pr=6683 https://github.com/github/gh-aw-mcpg/actions/runs/26638527237/job/78504913249?pr=6683

[Copilot]

@copilot fix this failing ci checks https://github.com/github/gh-aw-mcpg/actions/runs/26638527237/job/78504913214?pr=6683 https://github.com/github/gh-aw-mcpg/actions/runs/26638527237/job/78504913249...

Fixed in the latest commit. The upstreamHost() function was missing its closing }, which caused a parse error cascading into forwardToGitHub's signature. Build and proxy tests now pass locally.