refactor: extract repeated OTEL span-start patterns into named tracing helpers

[Copilot]

Four near-identical GetTracer().Start(...) blocks across server/unified.go and proxy/handler.go shared the same attribute sets and span-kind declarations with no shared abstraction, creating attribute-ordering drift and a maintenance burden for future spec updates.

Changes

• internal/tracing/span_helpers.go — four new named constructors, each encoding span name, attributes, and kind:

  • StartToolCallSpan → mcp.tool_call (Internal)
  • StartBackendExecuteSpan → gateway.backend.execute (Client)
  • StartDIFCPipelineSpan → proxy.difc_pipeline (Internal)
  • StartProxyForwardSpan → proxy.backend.forward (Client)

• internal/server/unified.go / internal/proxy/handler.go — inline span blocks replaced with the new helpers; now-unused oteltrace imports removed.

• internal/tracing/span_helpers_test.go — tests for each helper asserting span name, kind, and attribute values.

// Before — repeated at 4 call sites with varying attribute order
ctx, execSpan := us.GetTracer().Start(ctx, "gateway.backend.execute",
    oteltrace.WithAttributes(
        tracing.GenAIToolName.String(toolName),
        tracing.GenAIAgentID.String(serverID),
    ),
    oteltrace.WithSpanKind(oteltrace.SpanKindClient),
)

// After
execCtx, execSpan := tracing.StartBackendExecuteSpan(ctx, us.GetTracer(), serverID, toolName)

[Copilot]

Pull request overview

This PR extracts four repeated tracer.Start(...) call patterns from server/unified.go and proxy/handler.go into named constructor helpers in internal/tracing/span_helpers.go, reducing duplication and centralizing span name, kind, and attribute conventions. Tests verify each helper's span name, kind, and attributes via an in-memory exporter.

Changes:

• Added four new span-start helpers (StartToolCallSpan, StartBackendExecuteSpan, StartDIFCPipelineSpan, StartProxyForwardSpan).
• Replaced inline GetTracer().Start(...) blocks at four call sites and removed unused oteltrace imports.
• Added unit tests covering each helper.

Show a summary per file

File	Description
internal/tracing/span_helpers.go	New named span constructors encoding name/attrs/kind.
internal/tracing/span_helpers_test.go	In-memory exporter tests for each new helper.
internal/server/unified.go	Replaces two inline span starts with helpers; drops oteltrace import.
internal/proxy/handler.go	Replaces two inline span starts with helpers; drops oteltrace import.

Copilot's findings

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• Files reviewed: 4/4 changed files
• Comments generated: 0

[lpcox]

@copilot fix failing ci checks https://github.com/github/gh-aw-mcpg/actions/runs/26639206737/job/78507356943?pr=6684 https://github.com/github/gh-aw-mcpg/actions/runs/26639206737/job/78507356989?pr=6684

[Copilot]

@copilot fix failing ci checks https://github.com/github/gh-aw-mcpg/actions/runs/26639206737/job/78507356943?pr=6684 https://github.com/github/gh-aw-mcpg/actions/runs/26639206737/job/78507356989?pr=6...

Fixed in d620dc1 by removing an unused oteltrace import in internal/server/unified.go, which was causing both failing jobs (integration-test build step and lint go vet step). Local make build, make lint, and go test ./internal/server/... now pass.