feat(go): Resolve stdlib return types in variable extraction (PR-07)

[shivasurya]

Summary

• Extends Pass 2b (variable extraction) to resolve return types of Go stdlib function calls via the StdlibLoader attached to the module registry
• Previously, variables assigned from stdlib calls (e.g., resp := http.Get(url)) remained untyped; now they receive a concrete TypeFQN (e.g., net/http.Response)
• Adds inferTypeFromStdlibFunction helper that validates the import path is stdlib, calls StdlibLoader.GetFunction, and picks the first non-error return
• Adds normalizeStdlibReturnType helper that converts raw JSON type strings ("*Request", "string", "io.Reader") to TypeFQNs ("net/http.Request", "builtin.string", "io.Reader")
• Graceful degradation: when StdlibLoader is nil (network unavailable), variables remain untyped and no error is raised
• 21 new tests in go_variables_stdlib_test.go covering both helpers (unit) and three end-to-end ExtractGoVariableAssignments scenarios

Test plan

• go test ./graph/callgraph/extraction/... -v -run "TestNormalize|TestInferTypeFromStdlib|TestExtractGoVariables_Stdlib" — all 21 pass
• go test ./... — all 29 packages pass
• golangci-lint run ./graph/callgraph/extraction/... — 0 issues
• normalizeStdlibReturnType — 100% coverage; inferTypeFromStdlibFunction — 93.3%

🤖 Generated with Claude Code

[safedep]

SafeDep Report Summary

No dependency changes detected. Nothing to scan.

_{This report is generated by SafeDep Github App}

[codecov]

Codecov Report

❌ Patch coverage is 94.44444% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 83.32%. Comparing base (7a52822) to head (14ce58c).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...-engine/graph/callgraph/extraction/go_variables.go	94.44%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #554      +/-   ##
==========================================
+ Coverage   83.25%   83.32%   +0.06%     
==========================================
  Files         143      143              
  Lines       17710    17746      +36     
==========================================
+ Hits        14744    14786      +42     
+ Misses       2426     2423       -3     
+ Partials      540      537       -3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[shivasurya]

• feat(go): Replace hardcoded stdlib set with GoImportResolver struct (PR-09) #557
• feat(go): Add stdlib metadata to MCP call graph tool responses (PR-08) #556
• feat(go): Close stdlib type inference gap in GetReturnType (PR-07b) #555
• feat(go): Resolve stdlib return types in variable extraction (PR-07) #554 👈 (View in Graphite)
• feat(go): Wire stdlib loader into builder pipeline (PR-06) #553
• feat(go): Add Go version detection and stdlib loader init (PR-05) #552
• feat(go): Add Go stdlib R2 publishing pipeline (PR-04) #551
• feat(go): Add Go stdlib remote registry loader with lazy caching (PR-03) #549
• feat(go): Add Go stdlib extraction tool for registry generation (PR-02) #548
• feat(go): Add Go stdlib registry data structures and types (PR-01) #546
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[shivasurya]

Merge activity

• Feb 25, 3:17 AM UTC: A user started a stack merge that includes this pull request via Graphite.
• Feb 25, 3:29 AM UTC: Graphite rebased this pull request as part of a merge.
• Feb 25, 3:30 AM UTC: @shivasurya merged this pull request with Graphite.

[github-actions]

Code Pathfinder Security Scan

No security issues detected.

Metric	Value
Files Scanned	2
Rules	38

---

_{Powered by Code Pathfinder}