fix(amazonq): block completion before active edit is accepted/rejected

[bywang56]

Problem

Both completion suggestions (ghost text) and edit suggestions (diff view) could appear simultaneously due to a race condition. The EditSuggestionState flag was set too late in the edit display flow, allowing completion requests to check the state, see it as false, and proceed even while an edit was being displayed.

Solution

Fixed the race condition by setting the edit state immediately at the start of displaySvgDecoration() before any async operations:

• Set EditSuggestionState to true at the beginning of the edit flow
• Add state cleanup when edit cannot be shown (completion already active or invalid patch)
• Avoid calling clearDecorations() in displayEditSuggestion() to prevent premature state reset
• Check EditSuggestionState before making completion requests in recommendationService.ts.

This ensures only one suggestion type is displayed at a time with proper mutual exclusion.

---

• Treat all work as PUBLIC. Private feature/x branches will not be squash-merged at release time.
• Your code changes must meet the guidelines in CONTRIBUTING.md.
• License: I confirm that my contribution is made under the terms of the Apache 2.0 license.

[amazon-inspector-ohio]

⏳ I'm reviewing this pull request for security vulnerabilities and code quality issues. I'll provide an update when I'm done

[github-actions]

• This pull request modifies code in src/* but no tests were added/updated.
  • Confirm whether tests should be added or ensure the PR description explains why tests are not required.
• This pull request implements a feat or fix, so it must include a changelog entry (unless the fix is for an unreleased feature). Review the changelog guidelines.
  • Note: beta or "experiment" features that have active users should announce fixes in the changelog.
  • If this is not a feature or fix, use an appropriate type from the title guidelines. For example, telemetry-only changes should use the telemetry type.

[amazon-inspector-ohio]

✅ I finished the code review, and didn't find any security or code quality issues.

[bywang56]

/retryBuilds

[amazon-inspector-ohio]

⏳ I'm reviewing this pull request for security vulnerabilities and code quality issues. I'll provide an update when I'm done

[amazon-inspector-ohio]

✅ I finished the code review, and didn't find any security or code quality issues.

[amazon-inspector-ohio]

⏳ I'm reviewing this pull request for security vulnerabilities and code quality issues. I'll provide an update when I'm done

[amazon-inspector-ohio]

✅ I finished the code review, and didn't find any security or code quality issues.

[atonaamz]

Why do we need to move the logic to displaySvgDecoration? I think we clear decoration after making sure that all condition passes which is in displayEditSuggestion? should we just need the condition in recommendationService.ts?

if (!isTriggerByDeletion && !request.partialResultToken && !EditSuggestionState.isEditSuggestionActive()) {

[bywang56]

The check in recommendationService.ts alone isn't sufficient. Without setting the state early in displaySvgDecoration(), there's a race condition window between when the edit flow starts and when the state is finally set. During this window (which includes async operations like isCompletionActive() and applyPatch()), completion requests can check the state, see it as false, and proceed. Both changes are needed for proper mutual exclusion.

[atonaamz]

what if the state is set to false later and we already skip completion request?

[bywang56]

Setting state to TRUE early and then potentially setting it to FALSE later (if edit fails) is the correct behavior. When we set state to TRUE, we're indicating "an edit operation is in progress" - completion should be skipped during this time regardless of whether the edit ultimately succeeds or fails. If the edit fails, we clean up the state, and future completion requests will work normally. The alternative (not setting state early) is what causes the bug where both suggestions appear simultaneously.

[amazon-inspector-ohio]

⏳ I'm reviewing this pull request for security vulnerabilities and code quality issues. I'll provide an update when I'm done

[amazon-inspector-ohio]

✅ I finished the code review, and didn't find any security or code quality issues.