diff --git a/artifacts/artifacts.go b/artifacts/artifacts.go
index 995e178..ee43f21 100644
--- a/artifacts/artifacts.go
+++ b/artifacts/artifacts.go
@@ -6,100 +6,31 @@
 
 import (
 	"context"
-	"io"
 	"strings"
 
 	"cloud.google.com/go/storage"
-
-	"google.golang.org/api/iterator"
 )
 
-// ArtifactsClient provides access to Fuchsia build artifacts.
-type ArtifactsClient struct {
+// Client provides access to the artifacts produced by Fuchsia CI tasks.
+type Client struct {
 	client *storage.Client
 }
 
-// NewClient creates a new ArtifactsClient.
-func NewClient(ctx context.Context) (*ArtifactsClient, error) {
+// NewClient creates a new Client.
+func NewClient(ctx context.Context) (*Client, error) {
 	client, err := storage.NewClient(ctx)
 	if err != nil {
 		return nil, err
 	}
-	return &ArtifactsClient{client: client}, nil
+	return &Client{client: client}, nil
 }
 
-// List lists all objects in the artifact directory for the given build. bucket is the
-// Cloud Storage bucket for the given build.
-func (c *ArtifactsClient) List(ctx context.Context, bucket, build string) ([]string, error) {
-	dir := c.openDir(ctx, bucket, build)
-	return dir.list(ctx)
-}
-
-// Open returns a reader for an object in the artifact directory for the given build.
-// bucket is the Cloud Storage bucket for the given build.
-func (c *ArtifactsClient) Open(ctx context.Context, bucket, build, path string) (io.Reader, error) {
-	dir := c.openDir(ctx, bucket, build)
-	return dir.open(ctx, path)
-}
-
-// Create returns a storage.Writer for an object in the artifact directory. bucket is the
-// Cloud Storage bucket for the given build. build is the string Buildbucket build ID.
-// path is the object path relative to the root of the build artifact directory.
-func (c *ArtifactsClient) Create(ctx context.Context, bucket, build, path string) *storage.Writer {
-	dir := c.openDir(ctx, bucket, build)
-	return dir.create(ctx, path)
-}
-
-// openDir returns a Handle to a build's artifact directory within some bucket.
-func (c *ArtifactsClient) openDir(ctx context.Context, bucket, build string) *directory {
-	handle := c.client.Bucket(bucket)
-	return &directory{bucket: handle, build: build}
-}
-
-// directory is used to read from a Fuchsia build's Cloud Storage artifact "directory",
-// which is expected to live in a bucket containing the following hierarchy, where
-// "build-N" represents a possible directory:
-//
-// <bucket>/
-//         "builds"/
-//                  <build-1>/
-//                  <build-2>/
-//                  ...
-type directory struct {
-	bucket *storage.BucketHandle
-	build  string
-}
-
-// open returns an io.Reader for the given object in this directory.
-func (d *directory) open(ctx context.Context, object string) (io.Reader, error) {
-	object = strings.Join([]string{"builds", d.build, object}, "/")
-	return d.bucket.Object(object).NewReader(ctx)
-}
-
-// create returns a storage.Writer for the given object in this directory.
-func (d *directory) create(ctx context.Context, object string) *storage.Writer {
-	object = strings.Join([]string{"builds", d.build, object}, "/")
-	return d.bucket.Object(object).NewWriter(ctx)
-}
-
-// List lists all of the objects in this directory.
-func (d *directory) list(ctx context.Context) ([]string, error) {
-	prefix := strings.Join([]string{"builds", d.build}, "/")
-	iter := d.bucket.Objects(ctx, &storage.Query{
-		Prefix: prefix,
-	})
-
-	var items []string
-	for {
-		attrs, err := iter.Next()
-		if err == iterator.Done {
-			break
-		}
-		if err != nil {
-			return nil, err
-		}
-		items = append(items, strings.TrimPrefix(attrs.Name, prefix+"/"))
-	}
-
-	return items, nil
+// GetBuildDir returns the BuildDirectory for the given build. bucket is the GCS bucket.
+// build is the BuildBucket build ID.
+func (c *Client) GetBuildDir(bucket, build string) *BuildDirectory {
+	bkt := c.client.Bucket(bucket)
+	return &BuildDirectory{&Directory{
+		bucket: bkt,
+		root:   strings.Join([]string{"builds", build}, "/"),
+	}}
 }
diff --git a/artifacts/directory.go b/artifacts/directory.go
new file mode 100644
index 0000000..090d9b7
--- /dev/null
+++ b/artifacts/directory.go
@@ -0,0 +1,88 @@
+// Copyright 2019 The Fuchsia Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package artifacts
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"cloud.google.com/go/storage"
+	"google.golang.org/api/iterator"
+)
+
+// Directory is a handle to a Cloud Storage "directory". It provides a minimal
+// filesystem-like interface for a Cloud Storage object hierarchy where "/" is used as the
+// path separator. Any methods added to this struct are forward to other directory types.
+type Directory struct {
+	bucket *storage.BucketHandle
+	root   string
+}
+
+// Object returns a handle to the given object within this directory. path is the path to
+// the object relative to this directory.
+func (d *Directory) Object(path string) *storage.ObjectHandle {
+	path = fmt.Sprintf("%s/%s", d.root, path)
+	return d.bucket.Object(path)
+}
+
+// List lists all of the objects in this directory.
+func (d *Directory) List(ctx context.Context) ([]string, error) {
+	prefix := strings.Join([]string{d.root}, "/")
+	iter := d.bucket.Objects(ctx, &storage.Query{
+		Prefix: prefix,
+	})
+
+	var items []string
+	for {
+		attrs, err := iter.Next()
+		if err == iterator.Done {
+			break
+		}
+		if err != nil {
+			return nil, err
+		}
+		items = append(items, strings.TrimPrefix(attrs.Name, prefix+"/"))
+	}
+
+	return items, nil
+}
+
+// CD returns a handle to some child Directory of this Directory. It is up to the caller
+// to ensure that child exists and is actually a directory.
+func (d *Directory) cd(child string) *Directory {
+	return &Directory{
+		bucket: d.bucket,
+		root:   fmt.Sprintf("%s/%s", d.root, child),
+	}
+}
+
+// BuildDirectory represents a Fuchsia CI build's artifact directory. Refer to the
+// layout in doc.go for the layout of this directory. When amending the layout, prefer
+// adding methods to create new subdirectories on this type instead of calling Object()
+// with paths containing slashes. This encourages all clients of this package create
+// objects within this BuildDirectory using the same layout.
+type BuildDirectory struct {
+	*Directory
+}
+
+// Test returns the TestDirectory containing artifacts for a particular test. The name is
+// normalized according to normalizePathSegment.
+func (d BuildDirectory) Test(name string) *TestDirectory {
+	subdir := fmt.Sprintf("tests/%s", normalizePathSegment(name))
+	return &TestDirectory{d.Directory.cd(subdir)}
+}
+
+// TestDirectory contains artifacts for a particular test.
+type TestDirectory struct {
+	*Directory
+}
+
+// Env returns a Directory for objects relevant to an execution of this TestDirectory's
+// test in a particular environment. The name is normalized according to
+// normalizePathSegment.
+func (d TestDirectory) Env(name string) *Directory {
+	return d.Directory.cd(normalizePathSegment(name))
+}
diff --git a/artifacts/doc.go b/artifacts/doc.go
new file mode 100644
index 0000000..5071373
--- /dev/null
+++ b/artifacts/doc.go
@@ -0,0 +1,29 @@
+// Copyright 2019 The Fuchsia Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Package artifacts controls how files generated by Fuchsia's CI tasks are written to and
+// read from Cloud Storage.  The directory layout is defined below:
+//
+// gs://BUCKET/
+//     builds/
+//         BUILD/
+//             tests/
+//                 TEST/
+//                     ENVIRONMENT/
+//
+// BUCKET
+//     The Cloud Storage bucket used to store CI artifacts. Multiple buckets can exist
+//     exist using this scheme.
+// BUILD
+//     Contains all artifacts for a build. The directory's name is the unique BuildBucket
+//     build ID.
+// TEST
+//     Contains all artifacts relevant to a particular test.  The directory's name is the
+//     canonical name of the test - which is usually a test "suite".
+// ENVIRONMENT
+//     Contains all test artifacts relevant to a particular test environment. The
+//     directory's name is the canonical name of the test environment. Tests will often
+//     have multiple environment directories, because they often run in multiple
+//     environments per build.
+package artifacts
diff --git a/artifacts/normalize.go b/artifacts/normalize.go
new file mode 100644
index 0000000..5c4d80a
--- /dev/null
+++ b/artifacts/normalize.go
@@ -0,0 +1,31 @@
+// Copyright 2019 The Fuchsia Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package artifacts
+
+import (
+	"strings"
+)
+
+// Constants used to replace text in GCS object path segments.
+const (
+	// iFwdSlashSub is used in place of inner forward slashes.
+	iFwdSlashSub = "."
+
+	// iSpaceSub is used in place of inner \s characters.
+	iSpaceSub = "_"
+)
+
+// NormalizePathSegment rewrites a string so that it's safe to use as a GCS Object path.
+// This is useful for creating object paths from things like test names, which often
+// correspond to build target names and containing leading and inner forward slashes; Or
+// environment names, which often contain spaces or slashes for separating version
+// numbers.
+func normalizePathSegment(segment string) string {
+	segment = strings.TrimPrefix(segment, "//")
+	segment = strings.TrimSpace(segment)
+	segment = strings.Replace(segment, "/", iFwdSlashSub, -1)
+	segment = strings.Replace(segment, " ", iSpaceSub, -1)
+	return segment
+}
diff --git a/cmd/artifacts/copy.go b/cmd/artifacts/copy.go
index 3dd0b4c..ec7b1ef 100644
--- a/cmd/artifacts/copy.go
+++ b/cmd/artifacts/copy.go
@@ -84,13 +84,15 @@
 	return cmd.execute(ctx, buildsCli, artifactsCli)
 }
 
-func (cmd *CopyCommand) execute(ctx context.Context, buildsCli buildsClient, artifactsCli artifactsClient) error {
+func (cmd *CopyCommand) execute(ctx context.Context, buildsCli buildsClient, artifactsCli *artifacts.Client) error {
 	bucket, err := getStorageBucket(ctx, buildsCli, cmd.build)
 	if err != nil {
 		return err
 	}
 
-	input, err := artifactsCli.Open(ctx, bucket, cmd.build, cmd.source)
+	dir := artifactsCli.GetBuildDir(bucket, cmd.build)
+	obj := dir.Object(cmd.source)
+	input, err := obj.NewReader(ctx)
 	if err != nil {
 		return err
 	}
@@ -103,9 +105,3 @@
 	_, err = io.Copy(output, input)
 	return err
 }
-
-// artifactsClient fetches artifacts produced by Fuchsia builds.
-type artifactsClient interface {
-	List(ctx context.Context, bucket, build string) ([]string, error)
-	Open(ctx context.Context, bucket, build, path string) (io.Reader, error)
-}
diff --git a/cmd/artifacts/list.go b/cmd/artifacts/list.go
index 314af9a..cc66fe4 100644
--- a/cmd/artifacts/list.go
+++ b/cmd/artifacts/list.go
@@ -66,13 +66,14 @@
 	return cmd.execute(ctx, buildsCli, artifactsCli)
 }
 
-func (cmd *ListCommand) execute(ctx context.Context, buildsCli buildsClient, artifactsCli artifactsClient) error {
+func (cmd *ListCommand) execute(ctx context.Context, buildsCli buildsClient, artifactsCli *artifacts.Client) error {
 	bucket, err := getStorageBucket(ctx, buildsCli, cmd.build)
 	if err != nil {
 		return err
 	}
 
-	items, err := artifactsCli.List(ctx, bucket, cmd.build)
+	dir := artifactsCli.GetBuildDir(bucket, cmd.build)
+	items, err := dir.List(ctx)
 	if err != nil {
 		return err
 	}
diff --git a/go.mod b/go.mod
index b4dffba..c3ecbbf 100644
--- a/go.mod
+++ b/go.mod
@@ -5,10 +5,12 @@
 	github.com/golang/mock v1.2.0
 	github.com/golang/protobuf v1.2.0
 	github.com/google/martian v2.1.0+incompatible // indirect
+	github.com/google/pprof v0.0.0-20190309163659-77426154d546 // indirect
 	github.com/google/subcommands v0.0.0-20181012225330-46f0354f6315
 	github.com/google/uuid v1.1.0
 	github.com/googleapis/gax-go v2.0.2+incompatible // indirect
 	github.com/gopherjs/gopherjs v0.0.0-20181103185306-d547d1d9531e // indirect
+	github.com/ianlancetaylor/demangle v0.0.0-20181102032728-5e5cf60278f6 // indirect
 	github.com/jtolds/gls v4.2.1+incompatible // indirect
 	github.com/julienschmidt/httprouter v1.2.0 // indirect
 	github.com/maruel/subcommands v0.0.0-20181220013616-967e945be48b // indirect
@@ -18,6 +20,7 @@
 	github.com/texttheater/golang-levenshtein v0.0.0-20180516184445-d188e65d659e // indirect
 	go.chromium.org/luci v0.0.0-20181004001148-1bfb80352368
 	go.opencensus.io v0.19.0 // indirect
+	golang.org/x/arch v0.0.0-20190226203302-36aee92af9e8 // indirect
 	golang.org/x/crypto v0.0.0-20181203042331-505ab145d0a9
 	golang.org/x/net v0.0.0-20181217023233-e147a9138326
 	golang.org/x/sys v0.0.0-20181218192612-074acd46bca6
diff --git a/go.sum b/go.sum
index c676c8d..1a507c8 100644
--- a/go.sum
+++ b/go.sum
@@ -15,6 +15,8 @@
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5aqRK0M=
 github.com/google/martian v2.1.0+incompatible/go.mod h1:9I4somxYTbIHy5NJKHRl3wXiIaQGbYVAs8BPL6v8lEs=
+github.com/google/pprof v0.0.0-20190309163659-77426154d546 h1:r3n/h1Zh7Wpk29Q/b+FdrNjDAmr28WaPcxlI0c4NaeA=
+github.com/google/pprof v0.0.0-20190309163659-77426154d546/go.mod h1:zfwlbNMJ+OItoe0UupaVj+oy1omPYYDuagoSzA8v9mc=
 github.com/google/subcommands v0.0.0-20181012225330-46f0354f6315 h1:WW91Hq2v0qDzoPME+TPD4En72+d2Ue3ZMKPYfwR9yBU=
 github.com/google/subcommands v0.0.0-20181012225330-46f0354f6315/go.mod h1:ZjhPrFU+Olkh9WazFPsl27BQ4UPiG37m3yTrtFlrHVk=
 github.com/google/uuid v1.1.0 h1:Jf4mxPC/ziBnoPIdpQdPJ9OeiomAUHLvxmPRSPH9m4s=
@@ -24,6 +26,8 @@
 github.com/gopherjs/gopherjs v0.0.0-20181103185306-d547d1d9531e/go.mod h1:wJfORRmW1u3UXTncJ5qlYoELFm8eSnnEO6hX4iZ3EWY=
 github.com/grpc-ecosystem/grpc-gateway v1.5.0/go.mod h1:RSKVYQBd5MCa4OVpNdGskqpgL2+G+NZTnrVHpWWfpdw=
 github.com/grpc-ecosystem/grpc-gateway v1.6.2/go.mod h1:RSKVYQBd5MCa4OVpNdGskqpgL2+G+NZTnrVHpWWfpdw=
+github.com/ianlancetaylor/demangle v0.0.0-20181102032728-5e5cf60278f6 h1:UDMh68UUwekSh5iP2OMhRRZJiiBccgV7axzUG8vi56c=
+github.com/ianlancetaylor/demangle v0.0.0-20181102032728-5e5cf60278f6/go.mod h1:aSSvb/t6k1mPoxDqO4vJh6VOCGPwU4O0C2/Eqndh1Sc=
 github.com/jtolds/gls v4.2.1+incompatible/go.mod h1:QJZ7F/aHp+rZTRtaJ1ow/lLfFfVYBRgL+9YlvaHOwJU=
 github.com/julienschmidt/httprouter v1.2.0 h1:TDTW5Yz1mjftljbcKqRcrYhd4XeOoI98t+9HbQbYf7g=
 github.com/julienschmidt/httprouter v1.2.0/go.mod h1:SYymIcj16QtmaHHD7aYtjjsJG7VTCxuUUipMqKk8s4w=
@@ -52,6 +56,8 @@
 go.opencensus.io v0.18.0/go.mod h1:vKdFvxhtzZ9onBp9VKHK8z/sRpBMnKAsufL7wlDrCOA=
 go.opencensus.io v0.19.0 h1:+jrnNy8MR4GZXvwF9PEuSyHxA4NaTf6601oNRwCSXq0=
 go.opencensus.io v0.19.0/go.mod h1:AYeH0+ZxYyghG8diqaaIq/9P3VgCCt5GF2ldCY4dkFg=
+golang.org/x/arch v0.0.0-20190226203302-36aee92af9e8 h1:G3kY3WDPiChidkYzLqbniw7jg23paUtzceZorG6YAJw=
+golang.org/x/arch v0.0.0-20190226203302-36aee92af9e8/go.mod h1:cYlCBUl1MsqxdiKgmc4uh7TxZfWSFLOGSRR090WDxt8=
 golang.org/x/crypto v0.0.0-20181203042331-505ab145d0a9 h1:mKdxBk7AujPs8kU4m80U72y/zjbZ3UcXC7dClwKbUI0=
 golang.org/x/crypto v0.0.0-20181203042331-505ab145d0a9/go.mod h1:6SG95UA2DQfeDnfUPMdvaQW0Q7yPrPDi9nlGo2tz2b4=
 golang.org/x/exp v0.0.0-20190121172915-509febef88a4/go.mod h1:CJ0aWSM057203Lf6IL+f9T1iT9GByDxfZKAQTCR3kQA=
@@ -77,6 +83,7 @@
 golang.org/x/text v0.3.0 h1:g61tztE5qeGQ89tm6NTjjM9VPIm088od1l6aSorWRWg=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/tools v0.0.0-20180828015842-6cd1fcedba52/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
+golang.org/x/tools v0.0.0-20181219222714-6e267b5cc78e h1:XEcLGV2fKy3FrsoJVCkX+lMhqc9Suj7J5L/wldA1wu4=
 golang.org/x/tools v0.0.0-20181219222714-6e267b5cc78e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 google.golang.org/api v0.0.0-20180910000450-7ca32eb868bf/go.mod h1:4mhQ8q/RsB7i+udVvVy5NUi08OU8ZlA0gRVgrF7VFY0=
 google.golang.org/api v0.0.0-20181220000619-583d854617af/go.mod h1:4mhQ8q/RsB7i+udVvVy5NUi08OU8ZlA0gRVgrF7VFY0=