Speed up initial full indexing

[Widthdom]

Summary

• bound SQLite named-parameter statement sizes for caller-owned initial-index transactions across chunks, symbols, issues, reference lines, and references
• reduce reference-graph work with compact lower-rank guards, reusable target-key and property facts, fresh inline source attribution, and one-time C# type-family matching
• remove duplicate C# prepass/reference-line materialization, make manual performance tests explicitly runnable, and keep persistence telemetry bounded without weakening cancellation checkpoints

Root cause and impact

The empty-database path combined very large named-parameter statements with repeated graph candidate probes and duplicate temporary materialization. Microsoft.Data.Sqlite resolves parameter names during binding, so the previous 994-parameter reference statements were particularly expensive. The graph phase then repeated persistent candidate lookups and target-key construction over roughly one million candidate rows.

Measured on this repository with a new empty database:

Metric	origin/main baseline	This branch	Change
Full index	143.814 s	60.842 s	57.7% faster
Reference graph	68.912 s	8.595 s	87.5% faster
Peak working set	960.9 MB	804.4 MB	16.3% lower

The branch measurement indexed 1,411 files and 491,013 references, versus 1,399 files and 489,997 references in the baseline. Three preceding comparable branch runs had a 64.534 s median (64.351–86.887 s), with the slower first run reflecting cold-cache variance.

Validation

• Debug and Release solution builds: 0 warnings, 0 errors
• Release net8.0: 11,420 passed, 7 skipped, 0 failed
• Release net9.0: 10,948 passed, 418 skipped, 0 failed
• dotnet format CodeIndex.sln --verify-no-changes --no-restore
• dotnet run --project tools/CodeIndex.Changelog --no-restore -- check (14 fragments validated)
• fresh empty-database full-index benchmark on final HEAD
• root index and both workspace members healthy; graph/index/fold readiness current
• independent adversarial review: No blocking/actionable issues found.

Documentation and changelog

Updated the English/Japanese developer and testing guidance. Added these bilingual unreleased fragments:

• changelog.d/unreleased/+initial-index-write-batches.changed.md
• changelog.d/unreleased/+manual-performance-opt-in.changed.md
• changelog.d/unreleased/+compact-lower-rank-candidates.changed.md
• changelog.d/unreleased/+reference-resolution-symbol-facts.changed.md
• changelog.d/unreleased/+csharp-prepass-segmented-workspace.changed.md
• changelog.d/unreleased/+csharp-workspace-type-lookups.changed.md
• changelog.d/unreleased/+reference-line-window-sizing.changed.md
• changelog.d/unreleased/+csharp-property-receiver-facts.changed.md
• changelog.d/unreleased/+fresh-reference-source-attribution.changed.md
• changelog.d/unreleased/+csharp-type-family-candidates.changed.md

Follow-ups

Raw ordinal SQLite binding and candidate-schema compression remain possible higher-risk follow-ups; neither is required for this improvement set.