feat(vnext): add dialect-aware statement index

[Light2Dark]

Summary

• add an internal synchronous parser-free statement partition and binary-search cursor lookup
• preserve explicit half-open ownership for trivia, terminators, empty slots, EOF, and left/right affinity
• add bounded PostgreSQL, DuckDB, BigQuery, and Dremio lexical profiles with opaque fail-closed suffixes
• keep incremental reuse, session attachment, parser semantics, and public APIs out of this slice

Safety and performance

• cap materialized slots at 10,000 and collapse the remainder into one opaque slot
• bound dollar delimiters and retain no statement substrings
• conservatively handle Unicode dollar tags and prefix boundaries
• fail closed for BigQuery procedural bodies, custom delimiters, and PostgreSQL BEGIN ATOMIC bodies
• 16 MiB scans under a 128 MiB heap: about 44 ms ASCII, 61 ms Latin, 47 ms astral

Evidence

• exact head: 56b57ea
• focused statement-index tests: 82 passed
• full suite: 795 passed, 1 governed expected failure
• changed coverage: 98.76% statements, 96.97% branches, 100% functions, 98.75% lines
• strict typecheck, non-mutating lint, test integrity, demo build, packed-package smoke, and Chromium passed
• lexical/correctness reviewer: APPROVE exact head, no blocker/high/medium findings
• performance/API reviewer: APPROVE exact head, no blocker/high/medium findings

Public API

No vNext public exports or generated root declarations are added. The full scanner remains the correctness oracle for a later independently reviewed incremental slice.

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Summary by cubic

Adds an internal, dialect-aware SQL statement index for vNext. It partitions analysisText into exact half-open slots with binary-search cursor lookup and bounded resources, with no public API changes.

• New Features
  • Exact slot partitioning and ownership: terminators associate left; trailing trivia moves to the next slot; explicit empty slots are preserved.
  • Dialect profiles for PostgreSQL, DuckDB, BigQuery, and Dremio; protects strings/comments (e.g., dollar-quoting, E-strings, triple/raw/backtick, nested comments) and fails closed for custom delimiters, BigQuery procedural blocks, and PostgreSQL BEGIN ATOMIC.
  • Left/right-affinity lookup via binary search with explicit EOF behavior for terminated vs open statements.
  • Bounded resources: up to 10,000 materialized slots; bounded dollar-quote tag length; no statement substring copies; frozen partition data.
  • Reports unterminated strings/comments without exposing internal semicolons; operates on analysisText so UTF-16 offsets match the original text under the current masking transform; dialect behavior is keyed by internal profile identity, not a caller-controlled ID.

^{Written for commit 2ca3c25. Summary will update on new commits.}

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔵	Lines	98.76% (🎯 91%)	321 / 325
🔵	Statements	98.77% (🎯 91%)	322 / 326
🔵	Functions	100% (🎯 90%)	35 / 35
🔵	Branches	97.02% (🎯 85%)	294 / 303

File Coverage

File	Stmts	Branches	Functions	Lines	Uncovered Lines
Changed Files
src/vnext/statement-index.ts	98.77%	97.02%	100%	98.76%	197, 268, 473, 922

Generated in workflow #680 for commit 2ca3c25 by the Vitest Coverage Report Action

[Copilot]

Pull request overview

Adds an internal vNext “statement index” that partitions analysisText into dialect-aware, half-open statement slots (with explicit terminator/trivia ownership) and supports fast cursor-to-slot lookup via binary search, without introducing any new public vNext exports.

Changes:

• Introduces a bounded, parser-free SQL statement partitioner with per-dialect lexical profiles (PostgreSQL, DuckDB, BigQuery, Dremio) plus opaque fail-closed suffix behavior.
• Adds comprehensive Vitest coverage for partition semantics, cursor affinity, dialect-specific quoting/comment rules, resource caps, and deterministic properties.
• Documents slot semantics, cursor-affinity behavior, dialect profile intent, and source-coordinate rationale in vNext docs/ADR.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
src/vnext/statement-index.ts	New internal statement index builder + cursor lookup with dialect-aware lexical scanning and bounded opaque fallback.
src/vnext/tests/statement-index.test.ts	New focused tests covering partition correctness, affinity rules, dialect behaviors, and resource limits.
docs/vnext/statement-index.md	New documentation describing slot model, affinity semantics, profiles, and complexity guarantees.
docs/vnext/source-coordinates.md	Adds a brief cross-reference noting statement index scans analysisText offsets.
docs/adr/0001-language-service-and-session.md	Updates ADR with the statement-index oracle design and constraints for vNext sequencing.

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[cubic-dev-ai]

All reported issues were addressed across 5 files

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