Perf: coalesce runtime state snapshots

[MacHatter1]

Summary

Reduce redundant runtime snapshot construction and state broadcasts in the Electron runtime.

Why

Runtime commands were cloning and projecting the complete runtime state multiple times before a single command finished. The renderer could then receive repeated full snapshots for the same transaction, increasing main-process work, IPC payload churn, and React state replacement.

A small baseline measurement on an empty runtime showed one provider update constructing 3 snapshots, averaging 886 bytes each (2,658 bytes total).

What changed

• Centralise runtime.state broadcasts behind a transaction-aware helper.
• Queue at most one runtime-state broadcast marker per control transaction.
• Resolve all deferred state-bearing events from one final commit-time snapshot.
• Apply the same behaviour on the commit-state error path.
• Preserve existing event shapes and command result payloads.
• Add a regression test covering snapshot-call reduction and state-event delivery.

Validation

• npm run test:kernel — 539 tests passed; all kernel smoke checks passed.
• npm run test:ci — lint, full build, and 187 graph-core tests passed. Existing lint warnings remain.
• npm run check:electron — passed.
• npm run acceptance:electron — TypeScript source, compiled Electron entry, declarations, and smoke imports verified.
• Direct Electron validation:
  • Opened the workflow composer.
  • Changed the Coder provider from Claude Code to Codex and confirmed the Codex profile appeared.
  • Saved a workflow with a prompt and Codex selections.
  • Closed and reopened it from the saved-workflow catalogue.
  • Confirmed the prompt, provider/profile selections, workspace, runtime settings, review instruction, blocking policy, and lap limit were restored.
  • Removed the temporary test workflow afterwards.

Scope

This is intentionally limited to snapshot/broadcast churn. It does not change the public runtime event or command-result API.