fix(desktop): probe legacy Goose install dir on Windows (#3248)

Goose's pre-[#2680](https://github.com/block/buzz/pull/2680) Windows
installer unpacked the CLI to `%USERPROFILE%\goose\goose.exe`. That
directory is on no standard `PATH`, and `common_binary_paths()` never
probed it, so users who installed Goose with the legacy installer stayed
permanently undiscovered — the residual half of #2239.

`resolve_command_uncached` finds binaries outside `PATH` only by
scanning `common_binary_paths()`, so adding the directory there is the
whole fix: Windows basename expansion already supplies
`goose.exe`/`.cmd`/`.bat`, and discovery, readiness probes, and spawn
all route through the same shared resolver. No Goose-specific resolution
path is introduced. The entry sits beside the existing Codex
`%LOCALAPPDATA%\Programs\OpenAI\Codex\bin` probe in the same
`#[cfg(windows)]` block.

The regression test is `#[cfg(windows)]` and is CI-reachable, not dead
code — the `desktop-build-windows` job runs `cargo test --manifest-path
desktop/src-tauri/Cargo.toml --target $env:TARGET` on `windows-latest`.
It asserts the probe list rather than planting a binary:
`common_binary_paths` is a process-lifetime `OnceLock`, so a test cannot
deterministically re-seed `USERPROFILE`, and planting an executable
under the real user profile is not an acceptable side effect. Verified
locally by widening the `cfg` to build on macOS — the test passes with
the probe and fails without it.

The `check-file-sizes.mjs` override for `managed_agents/discovery.rs`
moves 1835 → 1841, the exact post-`cargo fmt` gate count. Verified both
directions: 1841 passes, 1840 fails.

Signed-off-by: Will Pfleger <pfleger.will@gmail.com>

desktop/scripts/check-file-sizes.mjs

@@ -344,7 +344,9 @@ const overrides = new Map([
   // absent, so AdapterMissing replaces the misleading NotInstalled. Includes
   // the deliberate-divergence doc comments; net after the inline preset
   // entries.push block collapsed into the helper.
-  ["src-tauri/src/managed_agents/discovery.rs", 1835],
+  // +6: legacy Goose Windows install dir (%USERPROFILE%\goose) probed in
+  // common_binary_paths so pre-#2680 standalone installs are discoverable.
+  ["src-tauri/src/managed_agents/discovery.rs", 1841],
   // BYOH — save_custom_harness_to_dir (backup-swap atomic write) + save_and_warm /
   // delete_and_warm (persist-mutex serialization for concurrent-safe registry
   // refresh, B-6). Also: id/collision/load/registry tests (from the file base) +

desktop/src-tauri/Cargo.lock

@@ -991,6 +991,7 @@ dependencies = [
 name = "buzz-core"
 version = "0.1.0"
 dependencies = [
+ "base64 0.22.1",
  "chrono",
  "hex",
  "hmac 0.13.0",

desktop/src-tauri/src/managed_agents/discovery.rs

@@ -58,6 +58,12 @@ fn common_binary_paths() -> &'static [PathBuf] {
                         .join("bin"),
                 );
             }
+            // Goose's legacy Windows installer (superseded by #2680) unpacked
+            // to %USERPROFILE%\goose\goose.exe, which is on no standard PATH —
+            // without this probe those installs stay permanently undiscovered.
+            if let Some(profile) = std::env::var_os("USERPROFILE") {
+                paths.push(PathBuf::from(profile).join("goose"));
+            }
         }
         paths
     })

desktop/src-tauri/src/managed_agents/discovery/tests/managed_path_resolution.rs

@@ -1,5 +1,31 @@
 use crate::managed_agents::discovery::{clear_resolve_cache, resolve_command};
 
+/// The legacy Goose Windows installer wrote `%USERPROFILE%\goose\goose.exe`,
+/// a directory on no standard PATH. `resolve_command_uncached` finds binaries
+/// outside PATH only by scanning `common_binary_paths()`, so that directory
+/// must appear there or those installs stay undiscovered (#2239 residual).
+///
+/// Asserts the probe list rather than a planted binary: `common_binary_paths`
+/// is a process-lifetime `OnceLock`, so a test cannot re-seed `USERPROFILE`
+/// deterministically, and planting an executable under the real user profile
+/// is not an acceptable test side effect.
+#[cfg(windows)]
+#[test]
+fn common_binary_paths_probes_legacy_goose_install_dir() {
+    use std::path::PathBuf;
+
+    let profile = std::env::var_os("USERPROFILE").expect("USERPROFILE is always set on Windows");
+    let legacy_dir = PathBuf::from(profile).join("goose");
+
+    let probed = super::super::common_binary_paths();
+
+    assert!(
+        probed.contains(&legacy_dir),
+        "legacy Goose install dir {} must be probed, got: {probed:?}",
+        legacy_dir.display()
+    );
+}
+
 #[cfg(unix)]
 #[test]
 fn resolve_command_prefers_buzz_managed_npm_shim_over_path() {