Smoke-test that pinned tools resolve to runnable binaries

.github/workflows/ci.yaml

@@ -50,3 +50,7 @@ jobs:
         with:
           auto-install: true
           cache: false
+
+      - name: Smoke-test binaries
+        shell: bash
+        run: ./scripts/smoke-test.sh

CONTRIBUTING.md

@@ -9,8 +9,9 @@ Each tool lives in its own directory containing a `plugin.toml` (the plugin) and
 version per tool and registers each plugin under `[plugins]` with a `file://` locator.
 
 CI installs every pinned tool through its local plugin across Linux, macOS (x64 and
-arm64), and Windows. A plugin that resolves and downloads on every platform is a green
-build; that install is the test, so there is no separate plugin test suite.
+arm64), and Windows, then runs `scripts/smoke-test.sh` to confirm each resolves to a
+runnable binary. Install alone is not enough: proto reports a wrong `exe-path` as a
+successful install and only fails when the dangling binary is used.
 
 ## Adding a plugin
 
@@ -69,6 +70,7 @@ from `.prototools`, not a hook-managed copy.
 ```sh
 proto run prek -- install              # optional: enable git hooks
 proto run prek -- run --all-files      # file hygiene, typos, taplo format + lint
+./scripts/smoke-test.sh                # every pinned tool resolves to a runnable binary
 ```
 
 ## Notes

scripts/smoke-test.sh

@@ -0,0 +1,35 @@
+#!/usr/bin/env bash
+# Assert every tool pinned in .prototools resolves to a real, runnable binary.
+# proto install only downloads and unpacks; it does not follow exe-path, so a
+# wrong exe-path produces a dangling symlink that install reports as success.
+# `proto bin` resolves exe-path and exits non-zero when the target is missing;
+# `proto run -- --version` then proves the binary actually executes.
+#
+# The tool list comes from the [plugins] table in .prototools (the repo's
+# single source of truth), read with the pinned taplo so adding a plugin needs
+# no edit here.
+set -euo pipefail
+
+cd "$(dirname "$0")/.."
+
+tools="$(proto run taplo -- get -f .prototools -o json 'plugins' | jq -r 'keys[]')"
+
+if [ -z "$tools" ]; then
+  echo "no tools found in [plugins] table of .prototools" >&2
+  exit 1
+fi
+
+failed=0
+for tool in $tools; do
+  if ! proto bin "$tool" >/dev/null 2>&1; then
+    echo "FAIL $tool: proto could not resolve an executable (check exe-path)"
+    failed=1
+  elif ! proto run "$tool" -- --version >/dev/null 2>&1; then
+    echo "FAIL $tool: resolved but did not run (--version exited non-zero)"
+    failed=1
+  else
+    echo "ok   $tool"
+  fi
+done
+
+exit "$failed"