Move TTL refresh into LocalStorage.Load, remove Session.Touch()

[yrobla]

Summary

Session.Touch() was a leaky abstraction — for Redis-backed sessions it was a no-op (GETEX already refreshes the TTL on read), while for LocalStorage the in-memory timestamp update was driven by the caller (Manager.Get) rather than the storage backend that actually needs it.

TTL refresh is now a storage concern: LocalStorage.Load updates the session's last-access timestamp via a package-local touchable interface, and Manager.Get no longer calls Touch(). Touch() is removed from the Session interface and from the MockMultiSession mock, eliminating the .EXPECT().Touch().AnyTimes() boilerplate across all session-related tests.

Fixes #4320

Type of change

• Bug fix
• New feature
• Refactoring (no behavior change)
• Dependency update
• Documentation
• Other (describe):

Test plan

• Unit tests (task test)
• E2E tests (task test-e2e)
• Linting (task lint-fix)
• Manual testing (describe below)

Changes

File	Change

Does this introduce a user-facing change?

Special notes for reviewers

[Copilot]

Pull request overview

This PR refactors session “last-access” / TTL refresh behavior to be owned by the storage backend: LocalStorage.Load now refreshes a session’s timestamp, and the Session.Touch() method is removed from the Session interface (with corresponding mock/test cleanup).

Changes:

• Remove Touch() from the Session interface and from gomock session mocks.
• Move LocalStorage “touch-on-access” behavior into LocalStorage.Load, and remove Manager.Get()’s call to Touch().
• Update unit/integration tests to stop expecting Touch() calls; adjust LocalStorage tests to assert auto-touch on Load.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
pkg/vmcp/session/types/mocks/mock_session.go	Removes mocked Touch() from MockMultiSession.
pkg/vmcp/server/sessionmanager/session_manager_test.go	Removes .EXPECT().Touch() boilerplate from session manager tests.
pkg/vmcp/server/session_management_integration_test.go	Removes .EXPECT().Touch() from integration test factories.
pkg/vmcp/server/integration_test.go	Removes .EXPECT().Touch() from integration tests.
pkg/vmcp/discovery/middleware_test.go	Removes .EXPECT().Touch() from middleware tests.
pkg/transport/session/storage_test.go	Updates LocalStorage tests to assert Load auto-touches and adjusts related comments.
pkg/transport/session/storage_local.go	Implements touch-on-Load via a package-local touchable interface.
pkg/transport/session/storage.go	Updates Storage.Load contract docs to describe TTL/last-access refresh behavior.
pkg/transport/session/manager.go	Removes Touch() from Session interface and from Manager.Get() behavior/docs.

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[codecov]

Codecov Report

❌ Patch coverage is 76.92308% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 68.89%. Comparing base (ce4123e) to head (ba8afac).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
pkg/transport/session/storage_local.go	76.92%	2 Missing and 4 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4337      +/-   ##
==========================================
- Coverage   69.30%   68.89%   -0.41%     
==========================================
  Files         478      479       +1     
  Lines       48425    48503      +78     
==========================================
- Hits        33559    33415     -144     
- Misses      12271    12320      +49     
- Partials     2595     2768     +173     

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[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 4 comments.

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