fix(daemon): forward the caller CLI's PATH per request for bare-name tool spawns

crates/fbuild-build-arm/src/generic_arm/arm_linker.rs

@@ -227,6 +227,8 @@ impl Linker for ArmLinker {
             &self.mcu_config.objcopy.output_format,
             &self.mcu_config.objcopy.remove_sections,
             "arm-none-eabi-objcopy",
+            // Absolute toolchain path; no caller-PATH overlay needed (#1219).
+            None,
         )
         .await
     }

crates/fbuild-build-arm/src/nrf52/nrf52_linker.rs

@@ -152,6 +152,8 @@ impl Linker for Nrf52Linker {
             &self.mcu_config.objcopy.output_format,
             &self.mcu_config.objcopy.remove_sections,
             "arm-none-eabi-objcopy",
+            // Absolute toolchain path; no caller-PATH overlay needed (#1219).
+            None,
         )
         .await
     }

crates/fbuild-build-arm/src/renesas/renesas_linker.rs

@@ -157,6 +157,8 @@ impl Linker for RenesasLinker {
             &self.mcu_config.objcopy.output_format,
             &self.mcu_config.objcopy.remove_sections,
             "arm-none-eabi-objcopy",
+            // Absolute toolchain path; no caller-PATH overlay needed (#1219).
+            None,
         )
         .await
     }

crates/fbuild-build-arm/src/sam/sam_linker.rs

@@ -173,6 +173,8 @@ impl Linker for SamLinker {
             &self.mcu_config.objcopy.output_format,
             &self.mcu_config.objcopy.remove_sections,
             "arm-none-eabi-objcopy",
+            // Absolute toolchain path; no caller-PATH overlay needed (#1219).
+            None,
         )
         .await
     }

crates/fbuild-build-arm/src/silabs/silabs_linker.rs

@@ -160,6 +160,8 @@ impl Linker for SilabsLinker {
             &self.mcu_config.objcopy.output_format,
             &self.mcu_config.objcopy.remove_sections,
             "arm-none-eabi-objcopy",
+            // Absolute toolchain path; no caller-PATH overlay needed (#1219).
+            None,
         )
         .await
     }

crates/fbuild-build-arm/src/teensy/teensy_linker.rs

@@ -204,6 +204,8 @@ impl Linker for TeensyLinker {
             &self.mcu_config.objcopy.output_format,
             &self.mcu_config.objcopy.remove_sections,
             "arm-none-eabi-objcopy",
+            // Absolute toolchain path; no caller-PATH overlay needed (#1219).
+            None,
         )
         .await
     }

crates/fbuild-build-engine/src/build_fingerprint/mod.rs

@@ -59,6 +59,14 @@ pub struct BinArtifactCache {
     pub flash_mode: String,
     pub flash_freq: String,
     pub flash_size: String,
+    /// Fingerprint of the esptool resolution that produced firmware.bin.
+    /// Empty when esptool is an absolute path (the resolution cannot
+    /// drift); a short hash of the caller's PATH when a bare-name spawn
+    /// resolves against it, so two requests with different caller PATHs
+    /// never share a cached bin (FastLED/fbuild#1219). `serde(default)`
+    /// keeps pre-existing absolute-path cache records valid.
+    #[serde(default)]
+    pub esptool_fingerprint: String,
 }
 
 #[derive(Debug, Clone, Serialize, Deserialize)]

crates/fbuild-build-engine/src/lib.rs

@@ -177,6 +177,12 @@ pub struct BuildParams {
     /// actually emitted. This unblocks per-symbol bloat analysis on
     /// over-budget builds. See FastLED/fbuild#594.
     pub bloat_analysis: bool,
+    /// Snapshot of the calling CLI's PATH, forwarded per request so
+    /// bare-name tool spawns (esptool, python, objcopy) resolve against
+    /// the caller's PATH instead of the daemon's potentially stale one.
+    /// `None` when no request context exists (tests, local CLI paths).
+    /// See FastLED/fbuild#1219.
+    pub caller_path: Option<String>,
 }
 
 /// Trait for platform-specific build orchestrators.

crates/fbuild-build-engine/src/linker.rs

@@ -466,6 +466,7 @@ impl LinkerBase {
         output_format: &str,
         remove_sections: &[String],
         tool_label: &str,
+        caller_path: Option<&str>,
     ) -> Result<PathBuf> {
         use fbuild_core::subprocess::run_command;
 
@@ -490,11 +491,14 @@ impl LinkerBase {
         args.push(hex_path.to_string_lossy().to_string());
 
         let args_ref: Vec<&str> = args.iter().map(|s| s.as_str()).collect();
+        // A bare objcopy name resolves against the caller's PATH; absolute
+        // toolchain paths are unaffected (FastLED/fbuild#1219).
+        let env = fbuild_core::subprocess::bare_name_path_overlay(args_ref[0], caller_path);
         // FastLED/fbuild#809: objcopy ELF→HEX/BIN bounded at 1 min.
         let result = run_command(
             &args_ref,
             None,
-            None,
+            env.as_ref().map(|e| &e[..]),
             Some(std::time::Duration::from_secs(60)),
         )
         .await?;

crates/fbuild-build-engine/src/pipeline/context.rs

@@ -69,9 +69,13 @@ impl BuildContext {
         let pio_overrides = fbuild_config::PioEnvOverrides::from_map(params.pio_env.clone());
         let config =
             fbuild_config::PlatformIOConfig::from_path_with_overrides(&ini_path, pio_overrides)?;
-        let overlay =
-            crate::script_runtime::resolve_extra_script_overlay(project_dir, env_name, &config)
-                .await?;
+        let overlay = crate::script_runtime::resolve_extra_script_overlay(
+            project_dir,
+            env_name,
+            &config,
+            params.caller_path.as_deref(),
+        )
+        .await?;
         if let Some(p) = perf.as_mut() {
             p.record("config-parse", t0.elapsed());
         }

crates/fbuild-build-engine/src/script_runtime.rs

@@ -41,6 +41,7 @@ pub async fn resolve_extra_script_overlay(
     project_dir: &Path,
     env_name: &str,
     config: &fbuild_config::PlatformIOConfig,
+    caller_path: Option<&str>,
 ) -> fbuild_core::Result<BuildOverlay> {
     let extra_scripts = config.get_extra_scripts(env_name)?;
     if extra_scripts.is_empty() {
@@ -61,7 +62,7 @@ pub async fn resolve_extra_script_overlay(
             .to_string(),
     };
 
-    let python = find_python().await.ok_or_else(|| {
+    let python = find_python(caller_path).await.ok_or_else(|| {
         fbuild_core::FbuildError::BuildFailed(
             "extra_scripts detected but no Python interpreter was found; \
              install Python or use --platformio"
@@ -116,10 +117,13 @@ pub async fn resolve_extra_script_overlay(
     // — config-time evaluation, never legitimately long. Bound to 60s
     // so a buggy or hostile script cannot wedge the daemon's build
     // pipeline indefinitely.
+    // The interpreter was resolved against the caller's PATH when it is a
+    // bare name — spawn it against the same PATH (FastLED/fbuild#1219).
+    let env = fbuild_core::subprocess::bare_name_path_overlay(argv[0], caller_path);
     let output = fbuild_core::subprocess::run_command(
         &argv,
         Some(project_dir),
-        None,
+        env.as_ref().map(|e| &e[..]),
         Some(std::time::Duration::from_secs(60)),
     )
     .await
@@ -298,7 +302,7 @@ fn libs_to_flags(
     Ok(flags)
 }
 
-pub async fn find_python() -> Option<Vec<String>> {
+pub async fn find_python(caller_path: Option<&str>) -> Option<Vec<String>> {
     let candidates: &[&[&str]] = if cfg!(windows) {
         &[&["python"], &["py", "-3"]]
     } else {
@@ -308,12 +312,15 @@ pub async fn find_python() -> Option<Vec<String>> {
     for candidate in candidates {
         let mut argv: Vec<&str> = candidate.to_vec();
         argv.push("--version");
+        // Probe against the caller's PATH so the daemon finds the same
+        // interpreter the CLI's environment would (FastLED/fbuild#1219).
+        let env = fbuild_core::subprocess::bare_name_path_overlay(candidate[0], caller_path);
         // FastLED/fbuild#809: `python --version` on the startup path —
         // bound tightly so a hung interpreter cannot wedge build init.
         if let Ok(output) = fbuild_core::subprocess::run_command(
             &argv,
             None,
-            None,
+            env.as_ref().map(|e| &e[..]),
             Some(std::time::Duration::from_secs(5)),
         )
         .await

crates/fbuild-build-engine/src/script_runtime_tests.rs

@@ -30,7 +30,7 @@ extra_scripts = {}
 async fn resolve_runtime_error(project_dir: &Path) -> String {
     let config =
         fbuild_config::PlatformIOConfig::from_path(&project_dir.join("platformio.ini")).unwrap();
-    resolve_extra_script_overlay(project_dir, "demo", &config)
+    resolve_extra_script_overlay(project_dir, "demo", &config, None)
         .await
         .unwrap_err()
         .to_string()
@@ -126,7 +126,7 @@ fn test_scope_to_link_overlay_maps_libpath_and_libs() {
 
 #[tokio::test]
 async fn test_resolve_extra_script_overlay_supports_dump_shim() {
-    if find_python().await.is_none() {
+    if find_python(None).await.is_none() {
         return;
     }
 
@@ -159,7 +159,7 @@ env.Append(CPPDEFINES=[\"DUMP_SHIM_OK\"])
     let config =
         fbuild_config::PlatformIOConfig::from_path(&project_dir.join("platformio.ini")).unwrap();
     // Pinned to MockEnv (see resolve_runtime_overlay note).
-    let overlay = resolve_extra_script_overlay(project_dir, "demo", &config)
+    let overlay = resolve_extra_script_overlay(project_dir, "demo", &config, None)
         .await
         .unwrap();
     assert!(
@@ -172,7 +172,7 @@ env.Append(CPPDEFINES=[\"DUMP_SHIM_OK\"])
 
 #[tokio::test]
 async fn test_resolve_extra_script_overlay_supports_common_noop_scons_helpers() {
-    if find_python().await.is_none() {
+    if find_python(None).await.is_none() {
         return;
     }
 
@@ -209,7 +209,7 @@ env.Append(CPPDEFINES=[\"HELPERS_SHIM_OK\"])
     let config =
         fbuild_config::PlatformIOConfig::from_path(&project_dir.join("platformio.ini")).unwrap();
     // Pinned to MockEnv (see resolve_runtime_overlay note).
-    let overlay = resolve_extra_script_overlay(project_dir, "demo", &config)
+    let overlay = resolve_extra_script_overlay(project_dir, "demo", &config, None)
         .await
         .unwrap();
     assert!(
@@ -222,7 +222,7 @@ env.Append(CPPDEFINES=[\"HELPERS_SHIM_OK\"])
 
 #[tokio::test]
 async fn test_resolve_extra_script_overlay_supports_board_config_shim() {
-    if find_python().await.is_none() {
+    if find_python(None).await.is_none() {
         return;
     }
 
@@ -256,7 +256,7 @@ env.Append(CPPDEFINES=[\"BOARD_CONFIG_SHIM_OK\"])
     let config =
         fbuild_config::PlatformIOConfig::from_path(&project_dir.join("platformio.ini")).unwrap();
     // Pinned to MockEnv (see resolve_runtime_overlay note).
-    let overlay = resolve_extra_script_overlay(project_dir, "demo", &config)
+    let overlay = resolve_extra_script_overlay(project_dir, "demo", &config, None)
         .await
         .unwrap();
     assert!(
@@ -269,7 +269,7 @@ env.Append(CPPDEFINES=[\"BOARD_CONFIG_SHIM_OK\"])
 
 #[tokio::test]
 async fn test_resolve_extra_script_overlay_supports_pio_platform_shim() {
-    if find_python().await.is_none() {
+    if find_python(None).await.is_none() {
         return;
     }
 
@@ -306,7 +306,7 @@ env.Append(CPPDEFINES=[\"PIO_PLATFORM_SHIM_OK\"])
     let config =
         fbuild_config::PlatformIOConfig::from_path(&project_dir.join("platformio.ini")).unwrap();
     // Pinned to MockEnv (see resolve_runtime_overlay note).
-    let overlay = resolve_extra_script_overlay(project_dir, "demo", &config)
+    let overlay = resolve_extra_script_overlay(project_dir, "demo", &config, None)
         .await
         .unwrap();
     assert!(
@@ -319,7 +319,7 @@ env.Append(CPPDEFINES=[\"PIO_PLATFORM_SHIM_OK\"])
 
 #[tokio::test]
 async fn test_resolve_extra_script_overlay_rejects_unsupported_script_prefix() {
-    if find_python().await.is_none() {
+    if find_python(None).await.is_none() {
         return;
     }
 
@@ -344,7 +344,7 @@ Import(\"env\")
 /// corrupt the harness's JSON-on-stdout protocol.
 #[tokio::test]
 async fn test_resolve_extra_script_overlay_tolerates_user_stdout_noise() {
-    if find_python().await.is_none() {
+    if find_python(None).await.is_none() {
         return;
     }
 
@@ -363,7 +363,7 @@ print(\"post-append noise\")
     );
     let config =
         fbuild_config::PlatformIOConfig::from_path(&temp.path().join("platformio.ini")).unwrap();
-    let overlay = resolve_extra_script_overlay(temp.path(), "demo", &config)
+    let overlay = resolve_extra_script_overlay(temp.path(), "demo", &config, None)
         .await
         .unwrap();
     assert!(
@@ -416,7 +416,7 @@ framework = arduino
 async fn resolve_runtime_overlay(project_dir: &Path) -> BuildOverlay {
     let config =
         fbuild_config::PlatformIOConfig::from_path(&project_dir.join("platformio.ini")).unwrap();
-    resolve_extra_script_overlay(project_dir, "demo", &config)
+    resolve_extra_script_overlay(project_dir, "demo", &config, None)
         .await
         .unwrap()
 }
@@ -428,7 +428,7 @@ async fn resolve_runtime_overlay(project_dir: &Path) -> BuildOverlay {
 /// `AddPostAction`. Source: MarlinFirmware/Marlin buildroot scripts.
 #[tokio::test]
 async fn test_shim_simple_marlin_cxxflags_style() {
-    if find_python().await.is_none() {
+    if find_python(None).await.is_none() {
         return;
     }
 
@@ -477,7 +477,7 @@ env.AddPostAction(\"$PROGPATH\", lambda *a, **k: None)
 /// emit `-Dkey=value`, not a malformed array entry.
 #[tokio::test]
 async fn test_shim_simple_inplace_tuple_cppdefine() {
-    if find_python().await.is_none() {
+    if find_python(None).await.is_none() {
         return;
     }
 
@@ -516,7 +516,7 @@ env.Append(CPPDEFINES=[\"PLAIN\"])
 /// `LINKFLAGS`, and registers a no-op post action.
 #[tokio::test]
 async fn test_shim_medium_default_environment_linkflags() {
-    if find_python().await.is_none() {
+    if find_python(None).await.is_none() {
         return;
     }
 
@@ -554,7 +554,7 @@ env.AddPostAction(\"$BUILD_DIR/firmware.bin\", after_build)
 /// script must not hard-fail and the parallel flag mutation must land.
 #[tokio::test]
 async fn test_shim_medium_nonflag_scope_does_not_reject() {
-    if find_python().await.is_none() {
+    if find_python(None).await.is_none() {
         return;
     }