Split Learning reset into exercise and unit

[Dhairya Patel (HABER7789)]

resetExercise reset one .qs file for Q# courses but wiped the entire notebook for notebook courses, while telling Copilot it "only resets an exercise." It now restores just the current activity one file, or one cell.

Adds resetUnit and a qdk-learning-reset-unit tool so chat can reset a whole unit, including by name.

Reset was picking the wrong notebook cell, because the stored position only moves when you run a cell, not when you click one. Now that #3627 has merged, reset resolves the selected cell by location the same way the hint and solution tools do. I also hardened the reset paths so a cancelled notebook close, rejected edit, or failed save aborts and keeps the user's progress instead of reporting success.

[Copilot]

Pull request overview

Splits QDK Learning resets into activity-level and unit-level operations.

Changes:

• Restores individual notebook cells without affecting other work.
• Adds whole-unit reset support for Q# and notebook courses.
• Exposes the new tool through Copilot, commands, telemetry, and agent guidance.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
source/vscode/src/telemetry.ts	Adds unit-reset telemetry.
source/vscode/src/learning/service.ts	Implements activity and unit reset behavior.
source/vscode/src/learning/python/materialization.ts	Restores individual notebook cells.
source/vscode/src/learning/notebookExercises.ts	Adds cell source lookup and replacement.
source/vscode/src/learning/commands.ts	Updates reset commands and notebook reopening.
source/vscode/src/gh-copilot/tools.ts	Registers the unit-reset tool.
source/vscode/src/gh-copilot/learningTools.ts	Adds tool orchestration and selected-cell synchronization.
source/vscode/package.json	Contributes the command and tool metadata.
source/vscode/ai/qdk-learning.agent.md	Documents activity versus unit resets.

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[Copilot]

🟡 Changes recommended

Notebook close, edit, save, and rematerialization failures can currently be reported as successful resets.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Review details

Suppressed comments (2)

source/vscode/src/learning/python/materialization.ts:136

• NotebookDocument.save() returns false when the document was not saved, but that result is ignored and the reset is reported as successful. In that case progress is cleared even though the restored cell was never persisted. Treat a false save result as a restoration failure rather than returning true.

  await notebook.save();
  return true;

source/vscode/src/learning/service.ts:1032

• rematerializeUnitWorkbook delegates to materializeNotebook, which catches every filesystem/parsing failure and returns void (materialization.ts:147-170). Consequently this call always proceeds to finishUnitReset, clearing completion and telling the command/tool that the unit was reset even when the workbook was unchanged. Propagate a failure result here and only clear progress after the workbook was successfully restored.

      await rematerializeUnitWorkbook(unit);

• Files reviewed: 9/9 changed files
• Comments generated: 2
• Review effort level: Balanced

[Copilot]

🟡 Changes recommended

Failed save paths can still discard learner work or incorrectly report a successful reset.

Get a fresh assessment by requesting another Copilot review.

Review details

• Files reviewed: 9/9 changed files
• Comments generated: 2
• Review effort level: Balanced