## Code Analysis

### Updated modules and harness interface assertions
`go.mod:11-14`
```go
github.com/dolthub/dolt/go v0.40.5-0.20261013070258-eaa9030af908
github.com/dolthub/go-mysql-server v0.20.1-0.20261013010327-d5acf30e8519
```
The repository uses the updated Dolt and go-mysql-server module versions implicated by the test result.

`testing/go/enginetest/doltgres_harness_test.go:54-68`
```go
type DoltgresHarness struct {
	t                  *testing.T
	setupData          []setup.SetupScript
	skippedQueries     []string
	queryEngine        *DoltgresQueryEngine
	parallelism        int
	skipSetupCommit    bool
	configureStats     bool
	useLocalFilesystem bool
}

var _ denginetest.DoltEnginetestHarness = &DoltgresHarness{}
var _ enginetest.SkippingHarness = &DoltgresHarness{}
var _ enginetest.ResultEvaluationHarness = &DoltgresHarness{}
var _ enginetest.DialectHarness = &DoltgresHarness{}
```
These compile-time assignments require `DoltgresHarness` to satisfy the external engine-test interfaces. The capability methods present in the harness include `SupportsNativeIndexCreation`, `SupportsForeignKeys`, and `SupportsKeylessTables`, but no `SupportsValueRow` method is defined in this type.

`testing/go/enginetest/doltgres_harness_test.go:334-344`
```go
func (d *DoltgresHarness) SupportsNativeIndexCreation() bool {
	return true
}

func (d *DoltgresHarness) SupportsForeignKeys() bool {
	return true
}

func (d *DoltgresHarness) SupportsKeylessTables() bool {
	return true
}
```

### Observed execution

```text
# Command: go build ./...
go version go1.26.2 linux/arm64
/usr/local/go/bin/go
INNER_BUILD_EXIT_STATUS=0

# Command: go test ./...
```

```text
testing/go/enginetest/doltgres_harness_test.go:65:43: cannot use &DoltgresHarness{} (value of type *DoltgresHarness) as "github.com/dolthub/dolt/go/libraries/doltcore/sqle/enginetest".DoltEnginetestHarness value in variable declaration: *DoltgresHarness does not implement "github.com/dolthub/dolt/go/libraries/doltcore/sqle/enginetest".DoltEnginetestHarness (missing method SupportsValueRow)
testing/go/enginetest/doltgres_harness_test.go:67:44: cannot use &DoltgresHarness{} (value of type *DoltgresHarness) as "github.com/dolthub/go-mysql-server/enginetest".ResultEvaluationHarness value in variable declaration: *DoltgresHarness does not implement "github.com/dolthub/go-mysql-server/enginetest".ResultEvaluationHarness (missing method SupportsValueRow)
testing/go/enginetest/doltgres_harness_test.go:68:35: cannot use &DoltgresHarness{} (value of type *DoltgresHarness) as "github.com/dolthub/go-mysql-server/enginetest".DialectHarness value in variable declaration: *DoltgresHarness does not implement "github.com/dolthub/go-mysql-server/enginetest".DialectHarness (missing method SupportsValueRow)
FAIL	github.com/dolthub/doltgresql/testing/go/enginetest [build failed]
TEST_EXIT_STATUS=1
```
The raw compiler output identifies the missing method at the harness interface assertions and shows that `testing/go/enginetest` failed to build.

The build completed successfully in the nested target container, but the full test command failed while compiling `testing/go/enginetest`; the compiler reported the same missing capability method at the interface assertions and related harness uses. Other listed packages produced passing or no-test output, but the package build failure caused the overall test command to exit 1.

### Result
The captured build and test commands, compiler output, and source excerpts support the reported failure: the updated dependency interfaces require `SupportsValueRow`, while `DoltgresHarness` does not provide it, blocking the full Go test suite.

### Test context
The outer runner initially lacked a Go executable; the commands above are the successful build and subsequent test execution from the nested target container with Go 1.26.2. No stubs, mocks, or bypasses were applied.