dagger/dagger · error

load canonical scratch directory: %w

Error message

load canonical scratch directory: %w

What it means

Wraps a failure to obtain the current Query from the context while loading the canonical scratch (empty) directory. CurrentQuery requires the caller to run inside a Dagger engine request with the query stored in ctx; without it, no SnapshotManager is reachable to create the scratch root. This is an infrastructure/context wiring error, not a content error.

Source

Thrown at core/directory.go:335

		lazy, err := decodePersistedDirectoryLazy(ctx, dag, persisted.LazyKind, persisted.LazyJSON)
		if err != nil {
			return nil, err
		}
		dir.Lazy = lazy
		return dir, nil
	default:
		return nil, fmt.Errorf("decode persisted directory payload: unsupported form %q", persisted.Form)
	}
}

func (*Directory) DecodePersistedObject(ctx context.Context, dag *dagql.Server, resultID uint64, _ *dagql.ResultCall, payload json.RawMessage) (dagql.Typed, error) {
	return decodePersistedDirectoryWithSnapshotRole(ctx, dag, resultID, payload, "snapshot")
}

func loadCanonicalScratchDirectory(ctx context.Context) (string, bkcache.ImmutableRef, error) {
	query, err := CurrentQuery(ctx)
	if err != nil {
		return "", nil, fmt.Errorf("load canonical scratch directory: %w", err)
	}
	scratchSnapshot, err := query.SnapshotManager().Scratch(ctx)
	if err != nil {
		return "", nil, err
	}
	return "/", scratchSnapshot, nil
}

type DirectoryWithDirectoryLazy struct {
	LazyState
	Parent      dagql.ObjectResult[*Directory]
	DestDir     string
	Source      dagql.ObjectResult[*Directory]
	Filter      CopyFilter
	Owner       string
	Permissions *int
}

View on GitHub (pinned to 82ba2681db)

Solutions

1. Ensure the code runs within a dagql-resolved call where CurrentQuery(ctx) returns the active *Query
2. Propagate the engine context (context.WithValue with the query key) into any goroutines or helpers
3. In tests, install a Query in the context before calling Directory APIs

Example fix

// before
result, err := dir.WithFile(ctx, ...) // background ctx, no query
// after
ctx = query.WithQuery(ctx, query) // or call within a resolved dagql field
result, err := dir.WithFile(ctx, ...)

// verify the context carries the query before calling core APIs
if CurrentQuery(ctx) == nil-or-errors {
    // install: ctx = query.WithQuery(ctx, q)
}

err := runDirOp(ctx)
var cqErr *queryMissingError
if errors.As(err, &cqErr) {
    ctx = query.WithQuery(ctx, q)
    err = runDirOp(ctx)
}

When it happens

Trigger: loadCanonicalScratchDirectory is invoked (via ensureRootFS, WithFile, WithSymlink, applyPatchFileResult, Diff) with a context that lacks the CurrentQuery value — e.g. calling core APIs outside a dagql-resolved request, using a background context, or context value dropped when spawning goroutines.

Common situations: Custom embeddings of the Dagger core that call Directory methods outside query resolution; tests that construct *Directory directly without CurrentQuery(ctx) setup; goroutines spawned without propagating the engine context.

Related errors

• decode persisted directory payload: missing lazy kind
• %s: unexpected result %T
• failed to load module source dependencies: %w
• unexpected context type for arg %s
• failed to evaluate changeset diff selector: %w

AI-assisted analysis of dagger/dagger@82ba2681db (2026-09-05). Data as JSON: /api/errors/e70e3391d8173a9e. Report an issue: GitHub.