Refactor MCP text-result parsing and remove responseWriter StatusCode shadowing

[Copilot]

The codebase had the same MCP content/text parsing logic duplicated across mcp, server, and difc, plus a responseWriter.StatusCode() method that shadowed the promoted BaseResponseWriter.StatusCode field. This change consolidates MCP text extraction into one shared path and makes server-side status handling consistent with the base writer pattern used elsewhere.

• Shared MCP text-content extraction

  • Added a shared helper for extracting concatenated text from raw MCP tool results.
  • Preserved compatibility with both decoded []interface{} content and []map[string]interface{} content produced by MCP response builders.
  • Kept internal/mcp as the package-facing entrypoint while moving the shared implementation into a cycle-free helper package.

• Server rate-limit detection

  • Replaced bespoke content traversal in internal/server/rate_limit.go with the shared extractor.
  • Centralized the text source used by both:
    • rate-limit error message extraction
    • rate-limit detection / reset parsing

• DIFC MCP response unwrapping

  • Updated unwrapMCPResponse in internal/difc/path_labels.go to reuse the same text extraction path before JSON unwrapping.
  • This also covers MCP responses built from []map[string]interface{} without duplicating traversal logic.

• Response writer status handling

  • Removed responseWriter.StatusCode() from internal/server/response_writer.go.
  • Updated server logging and tests to use the embedded BaseResponseWriter.StatusCode field directly, eliminating the method/field shadowing ambiguity.

• Focused test coverage

  • Added coverage for shared MCP text extraction across both MCP result shapes and malformed/non-text entries.
  • Added regression coverage for DIFC unwrapping and rate-limit text extraction using MCP text-response helpers.
  • Updated response-writer tests to validate direct field access.

Example of the status-code cleanup:

// before
logSDK.Printf("status=%d", lw.StatusCode())

// after
logSDK.Printf("status=%d", lw.StatusCode)

[Copilot]

Pull request overview

This PR consolidates MCP raw-result text extraction into a shared helper and removes responseWriter.StatusCode() to avoid method/field shadowing, updating server-side logging and tests accordingly.

Changes:

• Introduces internal/mcpresult.ExtractTextContent and wires internal/mcp.ExtractTextContentFromResult to it for shared MCP text extraction.
• Refactors rate-limit detection and DIFC MCP-response unwrapping to reuse the shared text extractor.
• Removes responseWriter.StatusCode() and updates logging/tests to use the embedded BaseResponseWriter.StatusCode field directly.

Show a summary per file

File	Description
internal/server/transport_test.go	Updates tests to assert StatusCode field instead of removed accessor method.
internal/server/response_writer.go	Removes StatusCode() method to eliminate method/field shadowing.
internal/server/rate_limit.go	Replaces bespoke MCP content/text traversal with shared MCP text extraction helper.
internal/server/middleware.go	Updates SDK logging to use lw.StatusCode field directly.
internal/server/http_helpers.go	Updates response logging to use lw.StatusCode field directly.
internal/server/circuit_breaker_test.go	Adds regression coverage for rate-limit text extraction using BuildMCPTextResponse.
internal/mcpresult/text_content.go	Adds shared implementation for extracting concatenated text from raw MCP tool result maps.
internal/mcp/tool_result.go	Adds ExtractTextContentFromResult wrapper to expose shared extraction via internal/mcp.
internal/mcp/tool_result_test.go	Adds focused tests for ExtractTextContentFromResult across supported shapes and malformed entries.
internal/difc/path_labels.go	Updates MCP response unwrapping to use shared text extractor before JSON unmarshal.
internal/difc/path_labels_test.go	Adds coverage for unwrapping []map[string]interface{}-shaped MCP responses.

Copilot's findings

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• Files reviewed: 11/11 changed files
• Comments generated: 1

[lpcox]

@copilot fix the failing ci check https://github.com/github/gh-aw-mcpg/actions/runs/27022607362/job/79754235458?pr=7041

[Copilot]

@copilot fix the failing ci check https://github.com/github/gh-aw-mcpg/actions/runs/27022607362/job/79754235458?pr=7041

Fixed in commit bb780f7.

I investigated the linked run and addressed the merge-ref lint failure (TestCopyTrimmedStringIntMap redeclared in this block) by updating internal/strutil/util_test.go to avoid the duplicate test symbol on the PR merge result. I also re-ran local lint/tests and final validation.

[lpcox]

@copilot resolve the merge conflicts in this pull request

[Copilot]

@copilot resolve the merge conflicts in this pull request

Resolved by merging origin/main into this PR branch and fixing the conflict in internal/strutil/util_test.go. Included in commit 1958a157.

[lpcox]

@copilot resolve the merge conflicts in this pull request

[Copilot]

@copilot resolve the merge conflicts in this pull request

Resolved by merging origin/main again and fixing the recurring conflict in internal/strutil/util_test.go (removing the duplicate CopyTrimmedStringIntMap tests from that file). Included in commits c6dfcf1c and 474770e9.