Preserve fractional numbers and Unicode in MSSQL parameters

[fubhy]

Summary

Default interpolation truncates fractional numbers through Int and can replace Unicode characters through VarChar code-page conversion.

Important

This PR starts with focused failing reproduction tests. Add the implementation fix to this same branch; CI is expected to fail until that fix is included.

Default parameter types lose numeric and Unicode data

Module: mssql/MssqlClient
Audit ID: sql-adapters-ms-1
Severity / confidence: high / high

What happens

Default interpolation truncates fractional numbers through Int and can replace Unicode characters through VarChar code-page conversion.

Why it happens

The adapter maps every number to Tedious Int and every string to VarChar instead of domain-preserving defaults such as Float and NVarChar.

Expected behavior

Ordinary interpolation must preserve finite JavaScript numbers and Unicode strings unless a caller explicitly chooses narrower SQL types.

Relevant implementation

These links and excerpts are pinned to audit base c9b56ab507f224426ee8388dc450da447ec4715f.

• packages/sql/mssql/src/MssqlClient.ts:359-370
• packages/sql/mssql/src/MssqlClient.ts:713-722

View problematic code at packages/sql/mssql/src/MssqlClient.ts:359-370

          if (values) {
            for (let i = 0, len = values.length; i < len; i++) {
              const value = values[i]
              const name = numberToParamName(i)

              if (isMssqlParam(value)) {
                req.addParameter(name, value.paramA, value.paramB, value.paramC)
              } else {
                const kind = Statement.primitiveKind(value)
                const type = parameterTypes[kind]
                req.addParameter(name, type, value)
              }

View exact lines on GitHub

View problematic code at packages/sql/mssql/src/MssqlClient.ts:713-722

export const defaultParameterTypes: Record<Statement.PrimitiveKind, DataType> = {
  string: Tedious.TYPES.VarChar,
  number: Tedious.TYPES.Int,
  bigint: Tedious.TYPES.BigInt,
  boolean: Tedious.TYPES.Bit,
  Date: Tedious.TYPES.DateTime,
  Uint8Array: Tedious.TYPES.VarBinary,
  Int8Array: Tedious.TYPES.VarBinary,
  null: Tedious.TYPES.Bit
}

View exact lines on GitHub

Reproduction

pnpm test --run packages/sql/mssql/test/DefaultParameterLossRepro.test.ts

Observed failure: FAIL: 1.5 validated as 1 and a valid Unicode character became a question mark under CP1252.

Implementation handoff

The initial reproduction tests on this branch are the regression specification for the implementation fix that should follow in this PR.

1. Start with the pinned implementation excerpts and the Why it happens analysis above.
2. Change the implementation so it satisfies the stated Expected behavior; do not weaken or remove the reproduction assertions.
3. Run the focused reproduction command(s) and confirm the observed failures become passing tests:

pnpm test --run packages/sql/mssql/test/DefaultParameterLossRepro.test.ts

4. Run the affected package's existing tests, then the repository lint and type checks before requesting review.

Audit provenance

• Audit base: c9b56ab507f224426ee8388dc450da447ec4715f
• Reproduction base: c9b56ab507f224426ee8388dc450da447ec4715f
• Findings: sql-adapters-ms-1
• Initial patch: focused reproduction tests; implementation fix pending

Closes EFF-337

[changeset-bot]

🦋 Changeset detected

Latest commit: cb834ff

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 30 packages

Name	Type
@effect/sql-mssql	Patch
effect	Patch
@effect/opentelemetry	Patch
@effect/platform-browser	Patch
@effect/platform-bun	Patch
@effect/platform-deno	Patch
@effect/platform-node-shared	Patch
@effect/platform-node	Patch
@effect/vitest	Patch
@effect/ai-anthropic	Patch
@effect/ai-openai-compat	Patch
@effect/ai-openai	Patch
@effect/ai-openrouter	Patch
@effect/atom-react	Patch
@effect/atom-solid	Patch
@effect/atom-vue	Patch
@effect/sql-clickhouse	Patch
@effect/sql-d1	Patch
@effect/sql-libsql	Patch
@effect/sql-mysql2	Patch
@effect/sql-pg	Patch
@effect/sql-pglite	Patch
@effect/sql-sqlite-bun	Patch
@effect/sql-sqlite-do	Patch
@effect/sql-sqlite-node	Patch
@effect/sql-sqlite-react-native	Patch
@effect/sql-sqlite-wasm	Patch
@effect/docgen	Patch
@effect/doctest	Patch
@effect/openapi-generator	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[pullfrog]

Important

This PR only adds reproduction tests — the implementation fix (changing defaultParameterTypes to use Float and NVarChar) has not been added yet. Merging as-is would land only failing tests.

Reviewed changes

• New test file DefaultParameterLossRepro.test.ts — two reproduction tests verifying that Int truncates fractional numbers and VarChar loses Unicode characters through codepage conversion.

  ^{｜ Fix all ➔ ｜ Fix 👍s ➔ ｜ View workflow run ｜ Using DeepSeek Pro (free via Pullfrog for OSS) (Kimi K2 not used — the program covers this model; add its provider key to run your pick) ｜ 𝕏}

[pullfrog]

✅ No new issues found.

Reviewed changes

• Changed defaultParameterTypes mappings — string now uses NVarChar instead of VarChar and number now uses Float instead of Int, preserving Unicode strings and fractional JavaScript numbers.
• Added unit tests — two tests in Client.test.ts validate that the new type objects' validate() methods preserve the input values.
• Added changeset — @effect/sql-mssql patch for the parameter type fix.

  ^{｜ View workflow run ｜ Using DeepSeek Pro (free via Pullfrog for OSS) (Kimi K2 not used — the program covers this model; add its provider key to run your pick) ｜ 𝕏}

[github-actions]

Bundle Size Analysis

Generated from PR build output; treat the content below as untrusted.

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batching.ts	9.86 KB	9.86 KB	0.00 KB (0.00%)
brand.ts	6.34 KB	6.34 KB	0.00 KB (0.00%)
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config.ts	20.60 KB	20.60 KB	0.00 KB (0.00%)
differ.ts	20.20 KB	20.20 KB	0.00 KB (0.00%)
http-client.ts	21.49 KB	21.49 KB	0.00 KB (0.00%)
logger.ts	10.76 KB	10.76 KB	0.00 KB (0.00%)
metric.ts	8.99 KB	8.99 KB	0.00 KB (0.00%)
optic.ts	7.18 KB	7.18 KB	0.00 KB (0.00%)
pubsub.ts	14.90 KB	14.90 KB	0.00 KB (0.00%)
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schedule.ts	10.74 KB	10.74 KB	0.00 KB (0.00%)
schema-class.ts	19.14 KB	19.14 KB	0.00 KB (0.00%)
schema-fromJsonSchemaDocument.ts	28.96 KB	28.96 KB	0.00 KB (0.00%)
schema-representation-roundtrip.ts	25.29 KB	25.29 KB	0.00 KB (0.00%)
schema-string-transformation.ts	13.30 KB	13.30 KB	0.00 KB (0.00%)
schema-string.ts	10.94 KB	10.94 KB	0.00 KB (0.00%)
schema-template-literal.ts	15.17 KB	15.17 KB	0.00 KB (0.00%)
schema-toArbitraryLazy.ts	21.94 KB	21.94 KB	0.00 KB (0.00%)
schema-toCodeDocument.ts	24.34 KB	24.34 KB	0.00 KB (0.00%)
schema-toCodecJson.ts	19.18 KB	19.18 KB	0.00 KB (0.00%)
schema-toEquivalence.ts	19.01 KB	19.01 KB	0.00 KB (0.00%)
schema-toFormatter.ts	18.87 KB	18.87 KB	0.00 KB (0.00%)
schema-toJsonSchemaDocument.ts	22.60 KB	22.60 KB	0.00 KB (0.00%)
schema-toRepresentation.ts	19.52 KB	19.52 KB	0.00 KB (0.00%)
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stm.ts	12.54 KB	12.54 KB	0.00 KB (0.00%)
stream.ts	9.79 KB	9.79 KB	0.00 KB (0.00%)