diff --git a/.github/workflows/ci-tests.yml b/.github/workflows/ci-tests.yml
index 5a379eb..6f6dc3f 100644
--- a/.github/workflows/ci-tests.yml
+++ b/.github/workflows/ci-tests.yml
@@ -58,7 +58,9 @@ jobs:
 
       - name: Format Spore files
         run: |
-          paths=(examples platform)
+          # `src/host.sp` is the package host entry; validate it via package/example flows,
+          # not standalone file-mode formatting.
+          paths=(examples src/basic_cli)
           if [ -d tests ]; then
             paths+=(tests)
           fi
@@ -67,7 +69,9 @@ jobs:
 
       - name: Check Spore files
         run: |
-          paths=(examples platform)
+          # `src/host.sp` is the package host entry; validate it via package/example flows,
+          # not standalone file-mode checks.
+          paths=(examples src/basic_cli)
           if [ -d tests ]; then
             paths+=(tests)
           fi
@@ -75,7 +79,9 @@ jobs:
 
       - name: Build Spore files
         run: |
-          paths=(examples platform)
+          # `src/host.sp` is the package host entry; validate it via package/example flows,
+          # not standalone file-mode builds.
+          paths=(examples src/basic_cli)
           if [ -d tests ]; then
             paths+=(tests)
           fi
diff --git a/.gitignore b/.gitignore
index 7c76b93..3a34a7e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,7 @@
 # Build artifacts
 target/
 host/target/
+/.spore-store
 
 # OS
 .DS_Store
diff --git a/README.md b/README.md
index bfd16e7..8a19506 100644
--- a/README.md
+++ b/README.md
@@ -20,12 +20,12 @@ Operating System
 
 | Module | Capabilities | Description |
 |--------|-------------|-------------|
-| `Stdout` | `uses [Console]` | Standard output |
-| `Stdin` | `uses [Console]` | Standard input |
-| `File` | `uses [FileRead]` or `uses [FileWrite]` | File system operations |
-| `Dir` | `uses [FileRead]` or `uses [FileWrite]` | Directory listing and creation |
-| `Env` | `uses [Env]` | Environment variables |
-| `Cmd` | `uses [Spawn]` | Process execution |
+| `basic_cli.stdout` | `uses [Console]` | Standard output |
+| `basic_cli.stdin` | `uses [Console]` | Standard input |
+| `basic_cli.file` | `uses [FileRead]` or `uses [FileWrite]` | File system operations |
+| `basic_cli.dir` | `uses [FileRead]` or `uses [FileWrite]` | Directory listing and creation |
+| `basic_cli.env` | `uses [Env]` | Environment variables |
+| `basic_cli.cmd` | `uses [Spawn]` | Process execution |
 
 ## Quick Start
 
@@ -43,19 +43,21 @@ spore run examples/hello.sp
 ```
 
 This repository currently keeps `examples/` limited to files that PR CI validates today.
-It also intentionally keeps the current loose `.sp` file layout for now; the manifest/package-layout migration is deferred to a follow-up change.
 
 ## Project Structure
 
 ```
 basic-cli/
-├── platform/          # Spore API modules (.sp files), checked and built in CI
-│   ├── Stdout.sp      # Standard output operations
-│   ├── Stdin.sp       # Standard input operations
-│   ├── File.sp        # File read/write operations
-│   ├── Dir.sp         # Directory operations
-│   ├── Env.sp         # Environment variable access
-│   ├── Cmd.sp         # Process execution
+├── spore.toml         # Platform manifest
+├── src/
+│   ├── host.sp        # Default platform entry point
+│   └── basic_cli/     # Spore API modules, checked and built in CI
+│       ├── stdout.sp  # Standard output operations
+│       ├── stdin.sp   # Standard input operations
+│       ├── file.sp    # File read/write operations
+│       ├── dir.sp     # Directory operations
+│       ├── env.sp     # Environment variable access
+│       └── cmd.sp     # Process execution
 ├── host/              # Rust host implementation
 │   ├── Cargo.toml
 │   └── src/
@@ -66,7 +68,7 @@ basic-cli/
 ## Tutorial Contract
 
 - `examples/` is for truthful, CI-validated examples only.
-- `platform/` is the API surface for the platform modules themselves.
+- `src/basic_cli/` is the API surface for the platform modules themselves.
 - Only add `tests/` when the repo has real Spore-side regression coverage worth running with `spore test`.
 
 If you want to add a new tutorial/example, treat this as the bar:
diff --git a/spore.toml b/spore.toml
new file mode 100644
index 0000000..cc23f3f
--- /dev/null
+++ b/spore.toml
@@ -0,0 +1,10 @@
+[package]
+name = "basic-cli"
+version = "0.1.0"
+type = "platform"
+spore-version = ">=0.1.0"
+
+[capabilities]
+allow = ["Compute"]
+
+[dependencies]
diff --git a/platform/Cmd.sp b/src/basic_cli/cmd.sp
similarity index 100%
rename from platform/Cmd.sp
rename to src/basic_cli/cmd.sp
diff --git a/platform/Dir.sp b/src/basic_cli/dir.sp
similarity index 100%
rename from platform/Dir.sp
rename to src/basic_cli/dir.sp
diff --git a/platform/Env.sp b/src/basic_cli/env.sp
similarity index 100%
rename from platform/Env.sp
rename to src/basic_cli/env.sp
diff --git a/platform/File.sp b/src/basic_cli/file.sp
similarity index 100%
rename from platform/File.sp
rename to src/basic_cli/file.sp
diff --git a/platform/Stdin.sp b/src/basic_cli/stdin.sp
similarity index 100%
rename from platform/Stdin.sp
rename to src/basic_cli/stdin.sp
diff --git a/platform/Stdout.sp b/src/basic_cli/stdout.sp
similarity index 100%
rename from platform/Stdout.sp
rename to src/basic_cli/stdout.sp
diff --git a/src/host.sp b/src/host.sp
new file mode 100644
index 0000000..389a630
--- /dev/null
+++ b/src/host.sp
@@ -0,0 +1,6 @@
+/// Platform startup adapter.
+/// This is where the platform sets up effect handlers before calling the application startup function.
+pub fn main_for_host(app_main: () -> ()) -> () {
+    app_main()
+    return
+}