feat(amazonq): support JupyterLab conversation history on refresh

[ruotingx]

Problem

In JupyterLab environments, when users start a new Q chat conversation and refresh their workspace, the active chat tab disappears and cannot be restored by clicking on it in the conversation history panel.

Solution

Allow multiple loadChats() calls in JupyterLab environment to enable conversation history access after refresh. In other IDEs, maintain existing behavior.

• Add JUPYTER_LAB environment variable detection
• Allow multiple loadChats() calls only in JupyterLab to restore open tabs
• Add test for JupyterLab environment with multiple loadChats() calls

License

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[manodnyab]

could we have a try catch block? does this env var exist by default for Jupyterlab?

[ruotingx]

This environment variable doesn't exist by default, we set it when starting the LSP server

def start_lsp_server(self, node_path, executable_path, auth_mode=None):
    env = os.environ.copy()
    env["JUPYTER_LAB"] = "true"  # We set this explicitly

Also tested this implementation on a SageMaker space where the JUPYTER_LAB environment variable is not
set, and the current functionalities still work, will not throw any errors.

Safe fallback behavior:

• When the env variable is not set: process.env.JUPYTER_LAB is undefined → undefined === 'true' → false → maintains existing behavior for all other IDEs
• When the env variable is set: process.env.JUPYTER_LAB is 'true' → 'true' === 'true' → true → enables JupyterLab-specific behavior

[manodnyab]

Would prefer one so that all cases are covered and ls does not crash

[ruotingx]

Would prefer one so that all cases are covered and ls does not crash

Done

[codecov-commenter]

Codecov Report

❌ Patch coverage is 80.95238% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 60.90%. Comparing base (9f745a3) to head (ec124fe).

Files with missing lines	Patch %	Lines
...rc/language-server/agenticChat/tabBarController.ts	80.95%	4 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2325   +/-   ##
=======================================
  Coverage   60.89%   60.90%           
=======================================
  Files         260      260           
  Lines       58313    58332   +19     
  Branches     3547     3550    +3     
=======================================
+ Hits        35512    35527   +15     
- Misses      22734    22738    +4     
  Partials       67       67           

Flag	Coverage Δ
unittests	60.90% <80.95%> (+<0.01%)	⬆️

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