fix(daemon): resolve test-emu project_dir against the caller's cwd (#1415)

crates/fbuild-daemon/src/handlers/emulator/mod.rs

@@ -23,6 +23,8 @@ mod tests_outcome;
 #[cfg(test)]
 mod tests_process;
 #[cfg(test)]
+mod tests_project_dir;
+#[cfg(test)]
 mod tests_select_runner;
 
 // --- Public API re-exports (preserve `handlers::emulator::*` paths) ---

crates/fbuild-daemon/src/handlers/emulator/select.rs

@@ -146,7 +146,11 @@ pub async fn test_emu(
         .request_id
         .clone()
         .unwrap_or_else(|| uuid::Uuid::new_v4().to_string());
-    let project_dir = PathBuf::from(&req.project_dir);
+    // Resolve against the caller's cwd, not the daemon's (FastLED/fbuild#1415).
+    let project_dir = crate::handlers::operations::resolve_request_project_dir(
+        &req.project_dir,
+        req.caller_cwd.as_deref(),
+    );
 
     // Mark the daemon as busy for the full build + emulate lifecycle.
     // Without this guard the 30 s self-eviction loop sees an "empty"
@@ -157,15 +161,18 @@ pub async fn test_emu(
     let _op_guard = crate::handlers::operations::OperationGuard::new(
         &ctx,
         fbuild_core::DaemonState::Building,
-        Some(format!("test-emu {}", req.project_dir)),
+        Some(format!("test-emu {}", project_dir.display())),
     );
 
     if !project_dir.exists() {
         return (
             StatusCode::BAD_REQUEST,
             Json(OperationResponse::fail(
                 request_id,
-                format!("project directory does not exist: {}", req.project_dir),
+                format!(
+                    "project directory does not exist: {}",
+                    project_dir.display()
+                ),
             )),
         );
     }

crates/fbuild-daemon/src/handlers/emulator/tests_project_dir.rs

@@ -0,0 +1,58 @@
+//! `POST /api/test-emu` must read a relative `project_dir` against the
+//! caller's cwd, not the daemon's (FastLED/fbuild#1415).
+
+use super::select::test_emu;
+use crate::context::DaemonContext;
+use crate::models::TestEmuRequest;
+use axum::Json;
+use axum::extract::State;
+use std::sync::Arc;
+
+fn request(project_dir: &str, caller_cwd: &std::path::Path) -> TestEmuRequest {
+    serde_json::from_value(serde_json::json!({
+        "project_dir": project_dir,
+        "caller_cwd": caller_cwd.to_str().unwrap(),
+    }))
+    .unwrap()
+}
+
+#[tokio::test]
+async fn relative_project_dir_resolves_against_caller_cwd() {
+    let (shutdown_tx, _rx) = tokio::sync::watch::channel(false);
+    let ctx = Arc::new(DaemonContext::new(0, shutdown_tx, "test".to_string()));
+    let caller = tempfile::tempdir_in(fbuild_paths::temp_subdir("daemon-tests")).unwrap();
+    // A platform no runner knows: reaching this error proves the handler read
+    // the caller's platformio.ini rather than the daemon cwd's (which has none).
+    std::fs::write(
+        caller.path().join("platformio.ini"),
+        "[env:x]\nplatform = bogus-platform-1415\nboard = x\n",
+    )
+    .unwrap();
+
+    let (_, Json(resp)) = test_emu(State(ctx), Json(request(".", caller.path()))).await;
+
+    assert!(!resp.success);
+    assert!(
+        resp.message.contains("bogus-platform-1415"),
+        "handler did not read the caller's project: {}",
+        resp.message
+    );
+}
+
+#[tokio::test]
+async fn missing_relative_project_dir_reports_the_resolved_path() {
+    let (shutdown_tx, _rx) = tokio::sync::watch::channel(false);
+    let ctx = Arc::new(DaemonContext::new(0, shutdown_tx, "test".to_string()));
+    let caller = tempfile::tempdir_in(fbuild_paths::temp_subdir("daemon-tests")).unwrap();
+
+    let (_, Json(resp)) = test_emu(State(ctx), Json(request("nope", caller.path()))).await;
+
+    assert!(!resp.success);
+    let expected = caller.path().join("nope");
+    assert!(
+        resp.message.contains(&expected.display().to_string()),
+        "message should name the resolved path {}: {}",
+        expected.display(),
+        resp.message
+    );
+}

crates/fbuild-daemon/src/handlers/operations/mod.rs

@@ -27,5 +27,5 @@ pub use reset::reset;
 
 // `pub(crate)` re-exports for sibling handler modules
 // (`handlers::emulator` consumes these).
-pub(crate) use common::{OperationGuard, qemu_extra_build_flags};
+pub(crate) use common::{OperationGuard, qemu_extra_build_flags, resolve_request_project_dir};
 pub(crate) use monitor::{MonitorOutcome, MonitorState};