fix(web): ignore stale runtime projection snapshots

[Pedro-Revez-Silva]

What Changed

• track the last applied shell projection version per environment in the runtime service
• drop stale shell snapshots and duplicate or out-of-order shell stream events instead of applying them
• add targeted tests for older-sequence, older-timestamp, duplicate-event, and newer-event cases

Why

The shell stream and shell snapshot recovery path can arrive out of order. When an older snapshot lands after a newer shell event or snapshot, the client can briefly replace the current project and thread state with stale data. That shows up as threads or projects disappearing and then reappearing on the next update.

This change makes shell projection application monotonic by sequence and timestamp so older state is ignored instead of overwriting newer state.

Checklist

• This PR is small and focused
• I explained what changed and why
• I included before/after screenshots for any UI changes
• I included a video for animation/interaction changes

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Note

Medium Risk
Changes the runtime environment projection sync to drop out-of-order snapshots and stream events; a bug in the version comparison/tracking could cause clients to ignore legitimate updates and appear stuck.

Overview
Makes shell projection application monotonic per environment by tracking the last applied {sequence, updatedAt} and ignoring stale shell snapshots (older sequence or same sequence with older updatedAt).

Also drops duplicate/out-of-order shell stream events by sequence, updates the tracked version after applying accepted events/snapshots, and clears this per-environment state on disconnect/test resets. Adds focused unit tests for snapshot/event acceptance and rejection edge cases.

^{Reviewed by Cursor Bugbot for commit 781f242. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Ignore stale runtime projection snapshots and events in environment service

• Adds shouldApplyProjectionSnapshot and shouldApplyProjectionEvent guards in service.ts to skip applying outdated data. Snapshots are compared by sequence first, then updatedAt as a tiebreaker; events require a strictly increasing sequence.
• Tracks the last applied projection version per environment in a new lastAppliedProjectionVersionByEnvironment map, cleared when a connection is removed.
• Behavioral Change: applyShellEvent and syncShellSnapshot handlers now silently drop duplicate or out-of-order updates instead of applying them.

^{Macroscope summarized 781f242.}

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[macroscopeapp]

Approvability

Verdict: Approved

This is a focused bug fix that adds sequence-based filtering to prevent stale projection snapshots and events from overwriting newer state in the runtime service. The logic is straightforward comparison operations with comprehensive test coverage.

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