fix(session): Don't send tool changed notifications if session not initialized yet

[david-hamilton-glean]

Description

AddSessionTools and DeleteSessionTools can be called before the session is registered, in particular in the RegisterSession hook.

They should not attempt to send notifications/tools/list_changed notifications in this case as it will only generate errors.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• MCP spec compatibility implementation
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Code refactoring (no functional changes)
• Performance improvement
• Tests only (no functional changes)
• Other (please describe):

Checklist

• My code follows the code style of this project
• I have performed a self-review of my own code
• I have added tests that prove my fix is effective or that my feature works
• I have updated the documentation accordingly

MCP Spec Compliance

• This PR implements a feature defined in the MCP specification
• Link to relevant spec section: Link text
• Implementation follows the specification exactly

Additional Information

Summary by CodeRabbit

• Bug Fixes
  • Notifications about tool list changes are now only sent after a session has been initialized, preventing premature notifications.
• Tests
  • Added tests to ensure tool addition and deletion during uninitialized sessions do not trigger notifications or errors, and that notifications are properly sent after initialization.

[coderabbitai]

Walkthrough

This change updates the session tool management logic to send tool list change notifications only if the session is initialized. It adds conditional checks in AddSessionTools and DeleteSessionTools methods and introduces tests verifying behavior when modifying tools before and after session initialization.

Changes

File(s)	Change Summary
server/session.go	Added conditional checks to send tool list change notifications only if the session is initialized in AddSessionTools and DeleteSessionTools.
server/session_test.go	Added tests for adding and deleting tools on uninitialized sessions, verifying that notifications are suppressed and error hooks are not triggered until after initialization.

Possibly related PRs

• Handle each session initialization separately #60: Introduced the session initialization methods (Initialized()), which are now used in this PR to conditionally control notification sending.

Suggested reviewers

• robert-jackson-glean

Warning

There were issues while running some tools. Please review the errors and either fix the tool's configuration or disable the tool if it's a critical failure.

🔧 golangci-lint (1.64.8)

Error: you are using a configuration file for golangci-lint v2 with golangci-lint v1: please use golangci-lint v2
Failed executing command with error: you are using a configuration file for golangci-lint v2 with golangci-lint v1: please use golangci-lint v2

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📥 Commits

Reviewing files that changed from the base of the PR and between 4f72e89 and 989faf8.

📒 Files selected for processing (2)

• server/session.go (2 hunks)
• server/session_test.go (1 hunks)

🚧 Files skipped from review as they are similar to previous changes (2)

• server/session.go
• server/session_test.go

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[rwjblue-glean]

Thanks for working on this! I left two very minor comments inline if you don't mind fixing.