Own settings cutover commit replay

[lynnswap]

Purpose

Keep settings cutover commit and deferred-intent replay alive even when the initiating runtime task is cancelled.

Changes

• Install one SettingsService-owned commit task and result before replay begins.
• Make concurrent callers for the same token and snapshot join the same operation.
• Prevent caller cancellation from cancelling backend replay or losing taken intents.
• Requeue and reproject raw intents after a genuine backend failure, preserving the real error for all waiters.
• Preserve token misuse, cancellation, and abort semantics while a commit is active or completed.

Testing

• Settings cutover suite (15 tests)
• Caller-cancellation race repeated 20 times
• swift test --build-system swiftbuild --no-parallel
• Compatibility consumer, API, and MCP gates
• ReviewMonitor xcodebuild test (15 tests)
• Exact concurrency and contract audit

Screenshots

Not applicable.

[lynnswap]

@codex review

[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: c4ff426fcd

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[lynnswap]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. What shall we delve into next?

Reviewed commit: 5260e0fbe8

ℹ️ About Codex in GitHub

Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you

• Open a pull request for review
• Mark a draft as ready
• Comment "@codex review".

If Codex has suggestions, it will comment; otherwise it will react with 👍.

Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".