feat(go): Close stdlib type inference gap in GetReturnType (PR-07b)

[shivasurya]

Summary

• Enhance GoTypeInferenceEngine.GetReturnType in resolution/go_types.go to fall back to the stdlib registry when the local user-code type map has no answer
• All code paths that call GetReturnType (type chaining, bidirectional inference, variable extraction) now receive stdlib type data automatically without any per-caller changes
• Add stdlibNormalizeType helper with the same pointer/slice/builtin/cross-package normalization logic as the extraction layer
• Fix extraction integration test: type now resolves via the engine (Source: "stdlib", Confidence: 1.0) instead of the extraction-layer fallback

Gap closed

Previously GoTypeInferenceEngine.GetReturnType only looked up user-code types. Any code path that called it for a stdlib function got (nil, false) even when StdlibLoader was set. The extraction-layer helper in go_variables.go worked around this for variable assignments, but chaining and bidirectional inference paths were still blind to stdlib types.

Test coverage

• go_types.go: 100% coverage on every function (15/15)
• stdlibNormalizeType: all branches covered (builtin, pointer, slice, cross-package, unqualified, empty)
• GetReturnType stdlib fallback: 10 new focused tests (nil loader, no dot, not stdlib, fn not found, error-only return, empty-typeFQN skip, local priority, pointer return, cross-package, simple function)
• Full test suite: all 30 packages green, 0 lint issues

Files changed

File	Change
resolution/go_types.go	Add stdlib fallback in GetReturnType + stdlibNormalizeType helper
resolution/go_types_test.go	Add mockGoTypesStdlibLoader, 10+ new tests covering all new branches
extraction/go_variables_stdlib_test.go	Update source assertion from stdlib_registry → stdlib

[safedep]

SafeDep Report Summary

No dependency changes detected. Nothing to scan.

_{This report is generated by SafeDep Github App}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.34%. Comparing base (806a944) to head (0b2c209).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #555      +/-   ##
==========================================
+ Coverage   83.30%   83.34%   +0.03%     
==========================================
  Files         143      143              
  Lines       17746    17782      +36     
==========================================
+ Hits        14784    14820      +36     
  Misses       2424     2424              
  Partials      538      538              

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[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 👈 (View in Graphite)
• feat(go): Resolve stdlib return types in variable extraction (PR-07) #554
• 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, 3:32 AM UTC: Graphite couldn't merge this PR because it had merge conflicts.
• Feb 25, 3:54 AM UTC: A user started a stack merge that includes this pull request via Graphite.
• Feb 25, 3:54 AM UTC: @shivasurya merged this pull request with Graphite.

[github-actions]

Code Pathfinder Security Scan

No security issues detected.

Metric	Value
Files Scanned	3
Rules	38

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