refactor: Abstract out FS access from icp-project

crates/icp-app/src/context/init.rs

@@ -106,8 +106,11 @@ pub fn initialize(
         pkg_cache,
     });
 
+    // The project's files come from this machine.
+    let files = Arc::new(icp_project::files::HostFileSystem);
+
     // Canister builder
-    let builder = Arc::new(Builder::new(wasm.clone()));
+    let builder = Arc::new(Builder::new(wasm.clone(), files.clone()));
 
     // Canister syncer
     let syncer = Arc::new(Syncer::host(wasm.clone()));
@@ -116,6 +119,7 @@ pub fn initialize(
     let pload = ProjectLoadImpl {
         project_root_locate: project_root_locate.clone(),
         recipe,
+        files: files.clone(),
     };
 
     let pload = Lazy::new(pload);
@@ -153,6 +157,7 @@ pub fn initialize(
     Ok(Context {
         host: Host {
             project: pload,
+            files,
             ids,
             artifacts,
             builder,

crates/icp-cli/src/commands/build.rs

@@ -65,6 +65,7 @@ pub(crate) async fn exec(ctx: &Context, args: &BuildArgs) -> Result<(), anyhow::
             environment_selection.name(),
             ctx.host.builder.clone(),
             ctx.host.artifacts.clone(),
+            ctx.host.files.as_ref(),
             reporter,
         )
         .await

crates/icp-cli/src/commands/project/bundle.rs

@@ -53,6 +53,7 @@ pub(crate) async fn exec(ctx: &Context, args: &BundleArgs) -> Result<(), anyhow:
 
     rendered(ctx.debug, async |reporter| {
         create_bundle(
+            ctx.host.files.as_ref(),
             &project.dir,
             canisters,
             &selected,

crates/icp-project/Cargo.toml

@@ -6,6 +6,18 @@ license = { workspace = true }
 publish.workspace = true
 
 [features]
+default = ["host"]
+# Implementations of this crate's seams that use the machine it is running on:
+# the filesystem and the project-local `.icp` stores. Turned off for a build
+# that has to run somewhere without them, such as inside a canister.
+#
+# It does not yet cover everything host-shaped here — the step runners still
+# spawn subprocesses and drive a wasmtime sandbox unconditionally, `create`
+# draws entropy from `rand`, and a bundle's plugin directories go through
+# `tar`'s own directory walk. Each is a seam of its own to draw, and every
+# dependency is still non-optional besides, so this is the boundary the feature
+# claims rather than a canister target.
+host = []
 # Exposes this crate's mocks and fixtures so downstream crates can test against
 # the same seams. Off in a normal build, so none of it ships.
 test-util = []

crates/icp-project/src/canister/build/mod.rs

@@ -40,11 +40,12 @@ pub trait Build: Sync + Send {
 /// a pre-built step by asking [`wasm::Fetch`] for the module.
 pub struct Builder {
     wasm: Arc<dyn wasm::Fetch>,
+    files: Arc<dyn crate::files::FileSystem>,
 }
 
 impl Builder {
-    pub fn new(wasm: Arc<dyn wasm::Fetch>) -> Self {
-        Self { wasm }
+    pub fn new(wasm: Arc<dyn wasm::Fetch>, files: Arc<dyn crate::files::FileSystem>) -> Self {
+        Self { wasm, files }
     }
 }
 
@@ -57,9 +58,14 @@ impl Build for Builder {
         reporter: &StepReporter,
     ) -> Result<(), BuildError> {
         match step {
-            BuildStep::Prebuilt(adapter) => {
-                Ok(prebuilt::build(adapter, params, reporter, self.wasm.as_ref()).await?)
-            }
+            BuildStep::Prebuilt(adapter) => Ok(prebuilt::build(
+                adapter,
+                params,
+                reporter,
+                self.wasm.as_ref(),
+                self.files.as_ref(),
+            )
+            .await?),
             BuildStep::Script(adapter) => Ok(script::build(adapter, params, reporter).await?),
         }
     }

crates/icp-project/src/canister/build/prebuilt.rs

@@ -1,7 +1,7 @@
 use icp_events::StepReporter;
 use snafu::prelude::*;
 
-use crate::{canister::wasm, fs, manifest::adapter::prebuilt::Adapter};
+use crate::{canister::wasm, manifest::adapter::prebuilt::Adapter};
 
 use super::Params;
 
@@ -11,14 +11,15 @@ pub enum PrebuiltError {
     Wasm { source: wasm::FetchError },
 
     #[snafu(display("failed to copy wasm to output file"))]
-    CopyFile { source: crate::fs::CopyError },
+    CopyFile { source: crate::files::FsError },
 }
 
 pub(super) async fn build(
     adapter: &Adapter,
     params: &Params,
     reporter: &StepReporter,
     wasm: &dyn wasm::Fetch,
+    files: &dyn crate::files::FileSystem,
 ) -> Result<(), PrebuiltError> {
     let src = wasm
         .wasm(
@@ -30,7 +31,10 @@ pub(super) async fn build(
         .await?;
 
     reporter.info(format!("Writing WASM file: {}", params.output));
-    fs::copy(&src, &params.output).context(CopyFileSnafu)?;
+    files
+        .copy(&src, &params.output)
+        .await
+        .context(CopyFileSnafu)?;
 
     Ok(())
 }