fix: do not propagate unrelated changes to other envs

[gastonfournier]

About the changes

This fixes a bug in delta / streaming propagation where a feature change in one environment could produce a feature-updated event in other connected environments, even when those environments had no in-scope change.

The issue was in ClientFeatureToggleDelta.updateFeaturesDelta(). It built one global set of changed feature names for the revision window and then, for every connected environment, reloaded those feature names in that environment and emitted feature-updated events.

That meant a change in production could cause a client streaming development to receive:

• a new eventId
• a feature-updated payload containing the current development state
• no actual change for the subscribed environment

So, from the client's point of view, this looked like a no-op update with a bumped revision.

This PR narrows feature refreshes by environment before reloading toggles:

• environment-specific events only refresh the matching connected environment
• environment-agnostic events still apply to all environments
• segment and removal behavior stay unchanged

I also added a regression test covering the case where a production-only feature update must not emit a synthetic development delta event.

Discussion points

This is intentionally the smaller correctness fix.

A possible follow-up would be to precompute affected environments and skip unaffected delta caches entirely, but that is not required to fix the incorrect payload propagation described above.

[github-actions]

@gastonfournier, core features have been modified in this pull request. Please review carefully!

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None

[Copilot]

Pull request overview

This PR adjusts the client feature toggle delta generation to avoid producing (and serving) deltas for environments that were not affected by a given change event, preventing unrelated environment updates from causing “no-op” deltas elsewhere.

Changes:

• Add environment-aware filtering when computing which feature toggles need to be refreshed per environment during delta updates.
• Remove the single cross-environment featuresUpdated list in favor of an environment-specific list computed inside the update loop.
• Add a unit test asserting that an update in one environment does not produce a delta for a different environment.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/lib/features/client-feature-toggles/delta/client-feature-toggle-delta.ts	Filters updated feature names per environment when refreshing delta caches.
src/lib/features/client-feature-toggles/delta/client-feature-toggle-delta.test.ts	Adds regression test to ensure unrelated environment changes don’t yield deltas.

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[github-actions]

API Changelog 7.5.1 vs. 7.5.1

No changes

[Copilot]

Pull request overview

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

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