perf(cache): passthrough uncached source files instead of tar-packing

crates/builtins/src/pluginfs/mod.rs

@@ -707,6 +707,9 @@ fn emit_glob_file(
             source_path,
             out_path: rel_str.to_string(),
             x: fh.exec,
+            // Workspace source file: durable for the build, so the engine can
+            // reference it by path instead of tar-packing it into the cache.
+            passthrough: true,
         }),
         hashout: fh.hashout.clone(),
     });
@@ -955,6 +958,9 @@ impl hplugin::driver::Driver for Driver {
                             source_path,
                             out_path: path.clone(),
                             x: fh.exec,
+                            // Workspace source file: durable for the build, so the
+                            // engine references it by path instead of tar-packing it.
+                            passthrough: true,
                         }),
                         hashout: fh.hashout.clone(),
                     }],

crates/engine/src/engine/request_state.rs

@@ -1,9 +1,10 @@
 use crate::engine::Engine;
 use crate::engine::error::{CycleError, TargetFailure};
-use crate::engine::local_cache::CacheArtifact;
 use crate::engine::meta::ResultMeta;
 use crate::engine::provider::State;
-use crate::engine::result::{ArtifactMeta, ExtendedTargetDef, LockedResolution, OutputMatcher};
+use crate::engine::result::{
+    ArtifactMeta, ExtendedTargetDef, LockedResolution, OutputMatcher, ResultArtifact,
+};
 use crate::engine::spec::EngineTargetSpec;
 use hcore::hasync::StdCancellationToken;
 use hcore::hmemoizer::Memoizer;
@@ -16,7 +17,7 @@ use std::ops::Deref;
 use std::sync::{Arc, Weak};
 
 type ArcErr = Arc<anyhow::Error>;
-type ExecuteCacheResult = Result<(Vec<CacheArtifact>, Vec<ArtifactMeta>), ArcErr>;
+type ExecuteCacheResult = Result<(Vec<ResultArtifact>, Vec<ArtifactMeta>), ArcErr>;
 type ProbeStatesResult = Result<Arc<Vec<State>>, ArcErr>;
 
 /// Pointer-keyed map entry for `DepDag` nodes.