fix(backend): pass install_env to postinstall

docs/configuration.md

@@ -178,7 +178,7 @@ See [Tools](/dev-tools/). In addition to specifying versions, each tool entry ca
 
 - `os`: Restrict installation to certain operating systems
 - `depends`: Install order relative to other tools in this config only; vfox plugin hook dependencies belong in plugin `metadata.lua` (see [Tool Dependencies](/dev-tools/#tool-dependencies))
-- `install_env`: Environment vars used during install
+- `install_env`: Environment vars used during install and tool-level `postinstall`
 - `postinstall`: Command to run after installation completes for that specific tool
 
 Examples:

docs/dev-tools/index.md

@@ -164,7 +164,7 @@ Behavior:
 
 - The command runs once the install completes successfully for that tool/version.
 - The tool's bin path is on PATH during the command, so you can invoke the installed tool directly.
-- Environment variables include `MISE_TOOL_INSTALL_PATH` pointing to the tool's install directory.
+- Environment variables include `MISE_TOOL_INSTALL_PATH` pointing to the tool's install directory and any variables from that tool's `install_env` option.
 - If the install fails, the `postinstall` command is not run.
 
 ## OS-Specific Tools

docs/hooks.md

@@ -75,6 +75,7 @@ Tool-level postinstall scripts receive the following environment variables:
 - `MISE_TOOL_NAME`: The short name of the tool (e.g., "node", "python")
 - `MISE_TOOL_VERSION`: The version that was installed (e.g., "20.10.0", "3.12.0")
 - `MISE_TOOL_INSTALL_PATH`: The path where the tool was installed
+- Variables from that tool's `install_env` option
 
 ## Task hooks
 

e2e/config/test_hooks_postinstall_env

@@ -15,7 +15,7 @@ EXPLICIT_PRE_TOOLS = {value = "explicitly_pre_tools", tools = false}
 POST_TOOLS_VAR = {value = "available_after_tools", tools = true}
 
 [tools]
-dummy = { version = "latest", postinstall = "echo PRE_TOOLS_VAR=\$PRE_TOOLS_VAR; echo EXPLICIT_PRE_TOOLS=\$EXPLICIT_PRE_TOOLS; echo POST_TOOLS_VAR=\$POST_TOOLS_VAR" }
+dummy = { version = "latest", install_env = { INSTALL_ENV_VAR = "available_during_install" }, postinstall = "echo PRE_TOOLS_VAR=\$PRE_TOOLS_VAR; echo EXPLICIT_PRE_TOOLS=\$EXPLICIT_PRE_TOOLS; echo POST_TOOLS_VAR=\$POST_TOOLS_VAR; echo INSTALL_ENV_VAR=\$INSTALL_ENV_VAR" }
 EOF
 
 # Remove any existing dummy installation to force reinstall
@@ -41,6 +41,14 @@ else
   exit 1
 fi
 
+if [[ $output == *"INSTALL_ENV_VAR=available_during_install"* ]]; then
+  echo "✓ INSTALL_ENV_VAR is available in postinstall"
+else
+  echo "✗ INSTALL_ENV_VAR is NOT available in postinstall"
+  echo "Output: $output"
+  exit 1
+fi
+
 # The post_tools var should be empty since it's marked as tools=true
 if [[ $output == *"POST_TOOLS_VAR="* ]]; then
   echo "✓ POST_TOOLS_VAR is empty as expected"

src/backend/mod.rs

@@ -1818,6 +1818,7 @@ pub trait Backend: Debug + Send + Sync {
                 env_vars.entry(k).or_insert(v);
             }
         }
+        env_vars.extend(tv.request.options().core.install_env);
 
         // Use the backend's list_bin_paths to get the correct binary directories
         // instead of hardcoding install_path/bin, which may not match the actual