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vscode/extensions
Ulugbek Abdullaev 3073c2bb48 NES: experiment-driven global token budget for the inline-edits prompt (#323948)
* nes: fold currentFile budgeting into the global budget cascade

Under the opt-in global budget experiment, the current file now draws its
clip budget from the shared pool (its `shares.currentFile` slice of
`totalTokens`) and donates whatever it does not use to the cascade as the
initial surplus. When the global budget is disabled (prod default) behavior
is byte-identical, and the new defaults (totalTokens 8000, shares in eighths)
reproduce today's per-part `maxTokens` caps exactly.

- xtabPromptOptions: add `GlobalBudgetSharePart`, `currentFileBudget()` and
  `validate()`; grow `shares` to include `currentFile`; bump
  `DEFAULT_TOTAL_TOKENS` to 8000 and rebalance `DEFAULT_SHARES`.
- promptCrafting: seed the cascade's initial surplus from the current file's
  leftover budget; delegate validation to the namespace helper.
- xtabProvider: size and clip the current file from the pool and compute the
  surplus, gated on `globalBudget` being defined.
- Tests: volume-neutral invariant, `currentFileBudget`/`validate` units, and
  provider-level regression + new-behavior coverage.
- Docs: rewrite globalBudgetCascade.md for the seeded-surplus design.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* nes: collapse global-budget settings into a single exp-driven JSON string

Replace the two experiment-driven global-budget settings
(globalBudget.enabled boolean + globalBudget.totalTokens number) with a
single JSON-encoded string setting, modelled after modelConfigurationString,
that defines totalTokens, order, and shares together.

- configurationService: remove InlineEditsXtabGlobalBudgetEnabled and
  InlineEditsXtabGlobalBudgetTotalTokens; add InlineEditsXtabGlobalBudget
  (string | undefined, ExperimentBased, default undefined).
- xtabPromptOptions: add GlobalBudgetOptions.VALIDATOR (all top-level fields
  optional; shares must be complete when present) and a pure
  GlobalBudgetOptions.fromConfigString(): Result<GlobalBudgetOptions, string>
  that JSON-parses, structurally validates, merges over the defaults, then
  runs the semantic validate(). Never throws.
- xtabProvider: inject ITelemetryService; resolve the budget via
  getGlobalBudget(), returning undefined (disabled, identical to prod) when
  the string is unset/empty/invalid and emitting incorrectNesGlobalBudgetConfig
  telemetry on parse/validation failure.
- Tests: migrate the provider global-budget tests to the JSON string and add
  fromConfigString unit tests.
- Docs: rewrite the globalBudgetCascade.md Wiring section and migration note.

No regression: an unset string keeps the byte-identical legacy path. '{}'
enables the budget with the volume-neutral defaults; {"totalTokens":N} only
overrides the pool size.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* nes: clip the current file last under a global budget to reuse cascade leftover

Under a global budget the current file is now clipped LAST, sized to its base
share plus whatever the budget cascade left unused (`currentFileBudget +
finalSurplus`), so it trims less and reuses leftover budget. The cascade runs
first (seeded with 0, the current file never donates) and is threaded into
`getUserPrompt` via `precomputedCascade` so it renders exactly once.

This replaces the earlier two-mode design: the opt-in `reuseLeftoverForCurrentFile`
flag and the seeded-surplus "donate-forward" path are dropped, along with all
`currentFileBudgetSurplus`/`initialSurplus` threading. Clip-last is now the single
behavior under a global budget. The validator hardening (rejecting non-finite or
negative `totalTokens`/shares) is kept.

No production regression: when `globalBudget` is undefined the current file is
still clipped to its own `currentFile.maxTokens` with the legacy await ordering,
byte-identical to before. The global budget remains experiment-gated and off in
prod.

Tests and globalBudgetCascade.md updated for the clip-last-only behavior.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

* nes: address review — restore nLinesOfCurrentFileInPrompt telemetry timing

- xtabProvider: record setNLinesOfCurrentFileInPrompt inside both budget
  branches. In the legacy/prod branch the clip happens before the
  context-gathering awaits, so the telemetry call is moved back there to
  match prod timing exactly (it is still emitted when a request is
  cancelled mid-gathering). The clip-last branch records it after the
  cascade, as the clip is inherently last there.
- xtabPromptOptions: fix two stale JSDoc blocks that still described the
  removed donate-forward behavior; describe clip-last instead.
- globalBudgetCascade.md: correct the conservation bound to T·(Σ shares)
  and document the share-sum tolerance (over-allocation ≤ ~1e-3·T).
- promptCrafting.spec: add a cascade test asserting finalSurplus shrinks
  as the cascade consumes budget (current file reuses less leftover).

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

* nes: fix stale DEFAULT_ORDER doc comment to say clip-last

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

* nes: rename clipCurrentFileToBudget param to overriddenMaxTokens

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

* nes: extract current-file clip + context gathering into a method

Pulls the ~55-line global-budget/legacy if-else out of doGetNextEditWithSelection
into a private gatherContextAndClipCurrentFile method returning
Result<{ clippedTaggedCurrentDoc, areaAroundCodeToEdit, precomputedCascade,
langCtx, neighborSnippets }, NoNextEditReason>. Behavior, clip-first/clip-last
ordering, and nLinesOfCurrentFileInPrompt telemetry timing are unchanged.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

* nes: recalibrate global-budget defaults to merged currentFile cap (1500)

main (#322382) lowered currentFile.maxTokens 2000->1500, which broke the
global-budget 'volume-neutral defaults' invariant (floor(total*share) must
equal each part's legacy cap). Recalibrate DEFAULT_SHARES to cap/7500 and set
DEFAULT_TOTAL_TOKENS to 7500 (the sum of the merged per-part caps: 1500 + 2000
+ 2000 + 1000 + 1000), so shares still sum to exactly 1 and every part's base
allocation reproduces its cap. finalSurplus stays 6000 (7500 - 1500).

Update dependent specs (literal 8000 -> DEFAULT_TOTAL_TOKENS, stale 2000 cap
comments -> 1500) and the design doc (defaults table, worked examples, effective
caps, ordering caveat, migration note) for T=7500 and currentFile base 1500.

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
2026-07-02 16:48:34 +00:00
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