[cherry-pick] nes: add optimized PatchBased02 prompt strategy

[vs-code-engineering]

Cherry-pick of #332018 from release/1.135.

Summary

Adds patchBased02Optimized, an implementation-neutral prompting strategy for the optimized inline-suggestion treatment. It inherits everything from patchBased02WithRecentLineNumbers (current/recent-file line numbers, cross-file edits/imports, disabled next-cursor prediction) and additionally bakes in the client, latency, and completions-unification knobs this unified model was tuned for, so a single promptingStrategy value carries the whole treatment rather than relying on many separate client settings or experiment/deployment toggles.

This makes the treatment self-contained enough to ship purely as the prompt template of a copilot-proxy /models deployment: the proxy only specifies promptStrategy: "patchBased02Optimized" and the client derives everything else.

Analogous to the change for 2-in-1 models made in this PR: #321755

Baked-in configuration

patchBased02Optimized spreads the shared patchBased02WithRecentLineNumbers config and adds:

Setting	Baked value
patchModelPredictionKind	currentLineCompleted
splitPatchOnDiff	true
patchFastYieldLineWithCursor	true
extraDebounceEndOfLine	0
nesMimicGhostTextBehavior	true
cacheDelay	200
rebasedCacheDelay	0
debounce	0
supportsUnifiedCompletions	true

How it works

• These are exposed as optional ModelConfiguration fields (each with a MODEL_CONFIGURATION_VALIDATOR entry), following the same pattern used to bake in allowImportChanges and supportsNextCursorLinePrediction.
• Every read site resolves via modelConfig.<field> ?? experimentDefault, so behavior is unchanged for any strategy that does not set a value.
• selectedModelConfiguration() returns the strategy-resolved config, so consumers outside xtabProvider observe the baked values:
  • xtabProvider (patchModelPredictionKind, splitPatchOnDiff, patchFastYieldLineWithCursor, extraDebounceEndOfLine) via the already-resolved model config.
  • NextEditProvider (cacheDelay, rebasedCacheDelay) and UserInteractionMonitor (debounce) inject IInlineEditsModelService.
  • inline completion provider (nesMimicGhostTextBehavior) via its existing model service.
• Adds a reusable NullInlineEditsModelService test double for the newly-injected dependency.

Completions unification

supportsUnifiedCompletions bakes completions unification into the strategy, following the exact supportsNextCursorLinePrediction precedent where a baked capability overrides the deployment toggle at each read site. When the selected NES model's strategy sets it, the client runs as the single unified provider — one baked boolean replaces all three unification settings:

• inlineCompletionProvider.ts: unification resolves via selectedModelConfiguration().supportsUnifiedCompletions ?? InlineEditsUnification (replaces github.copilot.chat.advanced.inlineEdits.unification).
• jointInlineCompletionProvider.ts: the baked flag is observed reactively (via onModelListUpdated) and OR-ed into the effective modelUnification, which both suppresses the separate GitHub Copilot completions provider and pushes github.copilot into the provider excludes (replaces inlineCompletionsUnificationModel (ExP) and excludedProviders: "completions,github.copilot" (local)).

The baked value never replaces the existing experiment path for other models — it only short-circuits it when set, so unrelated deployments are unaffected.

Intended deployment

{
  "modelConfiguration": {
    "modelName": "copilot-suggestions-lysithea-0024",
    "promptingStrategy": "patchBased02Optimized",
    "includeTagsInCurrentFile": false
  }
}

No inlineCompletionsUnificationModel / unification / excludedProviders toggles are required — the strategy carries them.

Testing

• npm run typecheck --prefix extensions/copilot
• focused Vitest coverage for applyStrategyConfig, MODEL_CONFIGURATION_VALIDATOR, pickSystemPrompt, NextEditProvider caching/speculative, and UserInteractionMonitor
• npm run precommit

[Copilot]

Pull request overview

Adds a self-contained optimized PatchBased02 prompting strategy for unified inline suggestions.

Changes:

• Bakes model, latency, caching, and unification settings into the strategy.
• Propagates strategy configuration across inline-edit providers.
• Adds supporting model-service stubs and tests.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
xtabPromptOptions.spec.ts	Tests strategy configuration.
inlineEditsModelService.ts (node)	Resolves selected strategy settings.
inlineEditsModelService.ts (common)	Adds null model service.
xtabPromptOptions.ts	Defines optimized strategy and settings.
xtabProvider.spec.ts	Covers prompt selection.
xtabProvider.ts	Applies optimized runtime settings.
promptCrafting.ts	Supports optimized prompt formatting.
jointInlineCompletionProvider.ts	Integrates unified completions.
inlineCompletionProvider.ts	Reads model-specific behavior.
userInteractionMonitor.spec.ts	Updates test dependencies.
nextEditProvider.ts	Applies model-specific cache delays.
userInteractionMonitor.ts	Applies model-specific debounce.

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