nes: add optimized PatchBased02 prompt strategy

[Julia Gong (juliagongms)]

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 an optimized PatchBased02 inline-edit prompting strategy while reusing existing behavior and configuration.

Changes:

• Registers patchBased02Optimized with shared PatchBased02 configuration.
• Routes prompt crafting, response parsing, and system prompts through PatchBased02 behavior.
• Adds focused configuration and system-prompt tests.

Show a summary per file

File	Description
xtabPromptOptions.spec.ts	Tests optimized strategy overrides.
xtabPromptOptions.ts	Defines and configures the strategy.
xtabProvider.spec.ts	Tests system-prompt selection.
xtabProvider.ts	Selects the PatchBased02 system prompt.
promptCrafting.ts	Uses PatchBased02 prompt construction.

Review details

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• Files reviewed: 5/5 changed files
• Comments generated: 0
• Review effort level: Balanced

[Mohammad javad Dianat (dianatofficial)]

Approved. The fix is minimal and correct.