Refactor env handling: extract MapToEnvSlice, clean up unused code

- Remove unused BuildSanitizedEnv function
- Extract MapToEnvSlice helper from MergeEnvVars
- MergeEnvVars now returns map, caller converts to []string
- Fix lint issues (gci, gofumpt, golines, whitespace)

💘 Generated with Crush

pkg/tools/shell.go

@@ -263,7 +263,7 @@ func (t *ExecTool) Execute(ctx context.Context, args map[string]any) *ToolResult
 
 	// Use sanitized environment - merge cached env with exec time vars and LLM extra env
 	// Note: cachedEnv is NOT re-filtered - PICOCLAW_* vars are preserved
-	cmd.Env = shell.MergeEnvVars(t.cachedEnv, execTimeEnv, extraEnv)
+	cmd.Env = shell.MapToEnvSlice(shell.MergeEnvVars(t.cachedEnv, execTimeEnv, extraEnv))
 
 	if cwd != "" {
 		cmd.Dir = cwd

pkg/tools/shell/env.go

@@ -52,12 +52,6 @@ var DefaultEnvAllowlist = map[string]bool{
 	"LC_COLLATE":        true,
 }
 
-// defaultEnvAllowPrefixes are env var prefixes that are always allowed.
-// Currently empty - all allowed vars are explicit in DefaultEnvAllowlist.
-var defaultEnvAllowPrefixes = []string{
-	// Currently empty - all allowed vars are explicit
-}
-
 // LLMBlocklist is the set of environment variable names that the LLM
 // cannot override, even if passed via the env parameter. These vars
 // control fundamental process behavior and could be exploited.
@@ -154,11 +148,11 @@ func isBlocked(key string) bool {
 	return false
 }
 
-// MergeEnvVars merges multiple env sources into a final []string for exec.Cmd.Env.
+// MergeEnvVars merges multiple env sources into a map.
 // baseEnv is the cached map from AllowedEnv.
 // envSet provides explicit key=value pairs (config, not filtered).
 // extraEnv provides additional key=value pairs from LLM (filtered by blocklist).
-func MergeEnvVars(baseEnv map[string]string, envSet, extraEnv map[string]string) []string {
+func MergeEnvVars(baseEnv map[string]string, envSet, extraEnv map[string]string) map[string]string {
 	vars := make(map[string]string, len(baseEnv)+len(envSet)+len(extraEnv))
 
 	// Start with base env (already filtered)
@@ -183,74 +177,12 @@ func MergeEnvVars(baseEnv map[string]string, envSet, extraEnv map[string]string)
 		}
 	}
 
-	// Convert to []string for exec.Cmd.Env
-	result := make([]string, 0, len(vars))
-	for k, v := range vars {
-		result = append(result, k+"="+v)
-	}
-	return result
+	return vars
 }
 
-// BuildSanitizedEnv constructs a sanitized environment []string suitable for
-// exec.Cmd.Env. It filters the inherited environment to only allowlisted variables.
-//
-// baseEnv is the inherited environment (e.g., from os.Environ() or cached).
-// If nil, os.Environ() will be used for backwards compatibility.
-// extraAllowlist adds additional variable names to the default allowlist.
-// envSet provides explicit key=value pairs from config (override inherited).
-// extraEnv provides additional key=value pairs from tool call (merged with envSet).
-func BuildSanitizedEnv(baseEnv []string, extraAllowlist []string, envSet, extraEnv map[string]string) []string {
-
-	// Use provided env or fall back to os.Environ
-	inherited := baseEnv
-	if inherited == nil {
-		inherited = os.Environ()
-	}
-
-	allowed := make(map[string]bool, len(DefaultEnvAllowlist)+len(extraAllowlist)+len(windowsEnvAllowlist))
-	for k := range DefaultEnvAllowlist {
-		allowed[envKey(k)] = true
-	}
-	if runtime.GOOS == "windows" {
-		for k := range windowsEnvAllowlist {
-			allowed[envKey(k)] = true
-		}
-	}
-	for _, k := range extraAllowlist {
-		allowed[envKey(k)] = true
-	}
-
-	vars := make(map[string]string, len(allowed)+len(envSet)+len(extraEnv))
-
-	for _, entry := range inherited {
-		k, v, ok := strings.Cut(entry, "=")
-		if !ok {
-			continue
-		}
-		norm := envKey(k)
-		if allowed[norm] || isAllowedPrefix(norm) {
-			vars[norm] = v
-		}
-	}
-
-	if envSet != nil {
-		for k, v := range envSet {
-			vars[envKey(k)] = v
-		}
-	}
-
-	// Merge extraEnv (tool call) - highest priority
-	// Filter against LLM blocklist to prevent override of sensitive vars
-	if extraEnv != nil {
-		for k, v := range extraEnv {
-			if LLMBlocklist[envKey(k)] {
-				continue // Skip blocked vars
-			}
-			vars[envKey(k)] = v
-		}
-	}
-
-	// Convert to []string for exec.Cmd.Env
+// MapToEnvSlice converts a map of environment variables to a []string
+// in the format "KEY=value" suitable for exec.Cmd.Env.
+func MapToEnvSlice(vars map[string]string) []string {
 	result := make([]string, 0, len(vars))
 	for k, v := range vars {
 		result = append(result, k+"="+v)
@@ -268,15 +200,6 @@ func envKey(k string) string {
 	return k
 }
 
-func isAllowedPrefix(name string) bool {
-	for _, prefix := range defaultEnvAllowPrefixes {
-		if strings.HasPrefix(name, prefix) {
-			return true
-		}
-	}
-	return false
-}
-
 // WithPicoclawEnvVars ensures PICOCLAW_* vars are set in envSet.
 // These are needed for child processes to locate config, workspace, etc.
 func WithPicoclawEnvVars(envSet map[string]string, workspace string) map[string]string {