diff --git a/README.md b/README.md
new file mode 100644
index 0000000..bb7932e
--- /dev/null
+++ b/README.md
@@ -0,0 +1,176 @@
+# post3
+
+**S3-compatible object storage you can run anywhere.**
+
+post3 is a lightweight, self-hosted S3-compatible storage server written in Rust. Store objects in PostgreSQL or on the local filesystem — your choice, same API. Works with any S3 client: the AWS SDK, the AWS CLI, boto3, MinIO client, or plain curl.
+
+## Why post3?
+
+- **Drop-in S3 compatibility** — 20+ S3 operations, validated against the [Ceph s3-tests](https://github.com/ceph/s3-tests) conformance suite (124 tests passing)
+- **Two backends, one API** — PostgreSQL (objects chunked into 1 MiB blocks) or local filesystem. Swap at startup with a flag.
+- **Zero external dependencies for FS mode** — No database, no message queue, no cloud account. Just the binary and a directory.
+- **Multipart uploads** — Full support for creating, uploading parts, completing, aborting, and listing multipart uploads. 5 GiB body limit.
+- **Custom metadata** — `x-amz-meta-*` headers preserved and returned on GET/HEAD
+- **Rust SDK included** — Ergonomic client wrapping `aws-sdk-s3` with sane defaults. One-liner setup.
+- **Built on proven foundations** — axum, tokio, sqlx, tower. Production-grade async Rust.
+
+## Quick Start
+
+### Filesystem backend (no database needed)
+
+```sh
+# Build and run
+cargo build --release -p post3-server
+./target/release/post3-server serve --backend fs --data-dir /tmp/post3-data
+```
+
+### PostgreSQL backend
+
+```sh
+# Start PostgreSQL and the server
+mise run up    # docker compose up (PostgreSQL 18)
+mise run dev   # start post3-server on localhost:9000
+```
+
+### Try it out
+
+```sh
+# Create a bucket
+curl -X PUT http://localhost:9000/my-bucket
+
+# Upload an object
+curl -X PUT http://localhost:9000/my-bucket/hello.txt \
+  -d "Hello, post3!"
+
+# Download it
+curl http://localhost:9000/my-bucket/hello.txt
+
+# List objects
+curl http://localhost:9000/my-bucket?list-type=2
+
+# Delete
+curl -X DELETE http://localhost:9000/my-bucket/hello.txt
+curl -X DELETE http://localhost:9000/my-bucket
+```
+
+Or use the AWS CLI:
+
+```sh
+alias s3api='aws s3api --endpoint-url http://localhost:9000 --no-sign-request'
+
+s3api create-bucket --bucket demo
+s3api put-object --bucket demo --key readme.md --body README.md
+s3api list-objects-v2 --bucket demo
+s3api get-object --bucket demo --key readme.md /tmp/downloaded.md
+```
+
+## Rust SDK
+
+```toml
+[dependencies]
+post3-sdk = { path = "crates/post3-sdk" }
+```
+
+```rust
+use post3_sdk::Post3Client;
+
+let client = Post3Client::new("http://localhost:9000");
+
+client.create_bucket("my-bucket").await?;
+client.put_object("my-bucket", "hello.txt", b"Hello, world!").await?;
+
+let data = client.get_object("my-bucket", "hello.txt").await?;
+assert_eq!(data.as_ref(), b"Hello, world!");
+
+// Large files — automatic multipart upload
+client.multipart_upload("my-bucket", "big-file.bin", &large_data, 8 * 1024 * 1024).await?;
+
+// List with prefix filtering
+let objects = client.list_objects("my-bucket", Some("logs/")).await?;
+```
+
+Since `post3-sdk` re-exports `aws_sdk_s3`, you can drop down to the raw AWS SDK for anything the convenience API doesn't cover.
+
+## Supported S3 Operations
+
+| Category | Operations |
+|----------|-----------|
+| **Buckets** | CreateBucket, HeadBucket, DeleteBucket, ListBuckets, GetBucketLocation |
+| **Objects** | PutObject, GetObject, HeadObject, DeleteObject |
+| **Listing** | ListObjects (v1 & v2), ListObjectVersions, delimiter/CommonPrefixes |
+| **Batch** | DeleteObjects (up to 1000 keys) |
+| **Multipart** | CreateMultipartUpload, UploadPart, CompleteMultipartUpload, AbortMultipartUpload, ListParts, ListMultipartUploads |
+| **Metadata** | Custom `x-amz-meta-*` headers on PUT, returned on GET/HEAD |
+
+## Architecture
+
+```
+crates/
+  post3/           Core library — StorageBackend trait, PostgresBackend,
+                   FilesystemBackend, models, migrations
+  post3-server/    HTTP server — axum-based, generic over any StorageBackend
+  post3-sdk/       Client SDK — wraps aws-sdk-s3 with ergonomic defaults
+ci/                CI pipeline — custom Dagger-based build/test/package
+```
+
+The server is generic over `B: StorageBackend`. Both backends implement the same trait, so the HTTP layer doesn't know or care where bytes end up.
+
+**PostgreSQL backend** splits objects into 1 MiB blocks stored as `bytea` columns. Seven tables with `ON DELETE CASCADE` for automatic cleanup. Migrations managed by sqlx.
+
+**Filesystem backend** uses percent-encoded keys, JSON metadata sidecars, and atomic writes (write-to-temp + rename). No database required.
+
+## S3 Compliance
+
+post3 is validated against the [Ceph s3-tests](https://github.com/ceph/s3-tests) suite — the same conformance tests used by Ceph RGW, s3proxy, and other S3-compatible implementations.
+
+```
+124 passed, 0 failed, 0 errors
+```
+
+Run them yourself:
+
+```sh
+git submodule update --init
+mise run test:s3-compliance       # run tests
+mise run test:s3-compliance:dry   # list which tests would run
+```
+
+## Development
+
+Requires [mise](https://mise.jdx.dev/) for task running.
+
+```sh
+mise run up                # Start PostgreSQL via docker compose
+mise run dev               # Run the server (localhost:9000)
+mise run test              # Run all tests
+mise run test:integration  # S3 integration tests only
+mise run check             # cargo check --workspace
+mise run build             # Release build
+mise run db:shell          # psql into dev database
+mise run db:reset          # Wipe and restart PostgreSQL
+```
+
+### Examples
+
+```sh
+mise run example:basic      # Bucket + object CRUD
+mise run example:metadata   # Custom metadata round-trip
+mise run example:aws-sdk    # Raw aws-sdk-s3 usage
+mise run example:cli        # AWS CLI examples
+mise run example:curl       # curl examples
+mise run example:large      # Large file stress test
+mise run example:multipart  # Multipart upload stress test
+```
+
+## Configuration
+
+| Variable | Default | Description |
+|----------|---------|-------------|
+| `POST3_HOST` | `127.0.0.1:9000` | Address to bind |
+| `DATABASE_URL` | — | PostgreSQL connection string (pg backend) |
+| `--backend` | `pg` | Storage backend: `pg` or `fs` |
+| `--data-dir` | — | Data directory (fs backend) |
+
+## License
+
+See [LICENSE](LICENSE) for details.
diff --git a/crates/post3-server/src/s3/handlers/buckets.rs b/crates/post3-server/src/s3/handlers/buckets.rs
index cb0a5b7..7fc5b59 100644
--- a/crates/post3-server/src/s3/handlers/buckets.rs
+++ b/crates/post3-server/src/s3/handlers/buckets.rs
@@ -10,7 +10,7 @@ use crate::state::State as AppState;
 
 fn is_valid_bucket_name(name: &str) -> bool {
     let len = name.len();
-    if len < 3 || len > 63 {
+    if !(3..=63).contains(&len) {
         return false;
     }
     // Must contain only lowercase letters, numbers, hyphens, and periods
@@ -30,11 +30,7 @@ fn is_valid_bucket_name(name: &str) -> bool {
         return false;
     }
     // Must not be formatted as an IP address
-    if name.split('.').count() == 4
-        && name
-            .split('.')
-            .all(|part| part.parse::<u8>().is_ok())
-    {
+    if name.split('.').count() == 4 && name.split('.').all(|part| part.parse::<u8>().is_ok()) {
         return false;
     }
     true
@@ -166,10 +162,7 @@ pub async fn list_buckets<B: StorageBackend>(
             StatusCode::OK,
             [
                 ("Content-Type", "application/xml".to_string()),
-                (
-                    "x-amz-request-id",
-                    uuid::Uuid::new_v4().to_string(),
-                ),
+                ("x-amz-request-id", uuid::Uuid::new_v4().to_string()),
             ],
             responses::list_buckets_xml(&buckets),
         )