NES: centralize NextEditProvider config reads into a per-request snapshot (#324752 item 4)

[ulugbekna]

Part of #324752 (item 4 — "Config reads scattered across ~13 call sites"). Layer 1 of a stacked refactor; layers #5 (per-request context object), #3 (split _getNextEditCanThrow), #1 (extract collaborators), and #6 (cleanups) will build on this branch.

What

getExperimentBasedConfig(...) was inlined at 13 call sites throughout nextEditProvider.ts. This centralizes those reads into per-request config snapshots computed once per request and threaded through the methods that need them, instead of reading config inline.

Two snapshot types are added to nesConfigs.ts:

• INesRequestConfigs (main request path) — isAsyncCompletions, debounceUseCoreRequestTime, autoExpandEditWindowLines, cacheDelay, rebasedCacheDelay, subsequentCacheDelay, speculativeRequestDelay. Read once in _getNextEditCanThrow via _readRequestConfigs() and threaded through fetchNextEdit → _executeNewNextEditRequest and computeMinimumResponseDelay (+ the debounce read).
• INesSpeculativeConfigs (speculative request path) — cursorPlacement, autoExpandEditWindowLinesSetting, autoExpandEditWindowLines. Read once at the top of _triggerSpeculativeRequest via _readSpeculativeConfigs() and threaded into _createSpeculativeRequest.

INesRequestConfigs extends INesConfigs, so the telemetry-facing { isAsyncCompletions } subset is unchanged.

Why two snapshots (not one)

The issue framed this as "one snapshot", but the reads actually span two independent request-producing flows — the main request and the speculative request — which are separate invocations. Using two focused snapshots (rather than one shared type) keeps each flow reading only its own experiment flags, so it does not shift experiment-exposure timing for the other flow's TeamInternal flags. This keeps the change strictly behavior-preserving, which matters because later layers stack on it.

Consolidation

• 11 of 13 inline reads consolidated into the two readers.
• 2 intentionally left as direct reads (now commented): InlineEditsAsyncCompletions in _cancelPendingRequestDueToDocChange (per-keystroke autorun gate) and InlineEditsSpeculativeRequests in handleShown (per-shown enablement gate). These are enablement gates checked outside a request lifecycle; folding them into a snapshot would run ~10 config reads per keystroke / shown-event for no functional gain.

Notes

• Main-flow telemetry + log side effects are preserved byte-for-byte (setNESConfigs(...) stays the { isAsyncCompletions } subset; the logged codeblock is unchanged).
• _expService is retained — still required by the NextEditCache constructor and the two gate reads. It could not be dropped.
• No functional behavior change; the only difference is that a flow now reads its full config set once up front (eager rather than conditional), which affects experiment-exposure timing within a flow only.

Validation

• cd extensions/copilot && npx vitest --run --pool=forks nextEditProvider → 3 files, 66 passed / 2 skipped (unchanged from baseline): nextEditProviderCaching.spec.ts, nextEditProviderSpeculative.spec.ts, nextEditProviderTelemetry.spec.ts.
• npx tsgo --noEmit --project tsconfig.json → clean.

[Copilot]

Pull request overview

This PR is layer 1 of a stacked refactor of nextEditProvider.ts (item 4 of tracking issue #324752). It replaces the 13 inlined getExperimentBasedConfig(...) reads with two per-request config snapshots computed once per request and threaded through the methods that consume them. This is a preparatory, behavior-preserving refactor that later layers (per-request context object, method splits, collaborator extraction) build upon.

Changes:

• Adds two snapshot interfaces to nesConfigs.ts: INesRequestConfigs (extends INesConfigs, main request path) and INesSpeculativeConfigs (speculative path).
• Introduces _readRequestConfigs() and _readSpeculativeConfigs() readers, replacing determineNesConfigs, and threads the snapshots through the relevant methods.
• Leaves 2 enablement-gate reads as direct reads (documented), and preserves the { isAsyncCompletions } telemetry/log subset exactly.

Show a summary per file

File	Description
extensions/copilot/src/extension/inlineEdits/node/nesConfigs.ts	Adds INesRequestConfigs and INesSpeculativeConfigs snapshot interfaces with JSDoc explaining the two-flow separation.
extensions/copilot/src/extension/inlineEdits/node/nextEditProvider.ts	Replaces inline config reads with two per-request readers, threads snapshots through request/speculative flows, and preserves telemetry/log side effects via an explicit INesConfigs subset.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Medium