fix: allow claude backend to read env from setting.json while preventing recursion (#92)

* fix: allow claude backend to read env from setting.json while preventing recursion

Fixes #89

Problem:
- --setting-sources "" prevents claude from reading ~/.claude/setting.json env
- Removing it causes infinite recursion via skills/commands/agents loading

Solution:
- Keep --setting-sources "" to block all config sources
- Add loadMinimalEnvSettings() to extract only env from setting.json
- Pass env explicitly via --settings parameter
- Update tests to validate dynamic --settings parameter

Benefits:
- Claude backend can access ANTHROPIC_API_KEY and other env vars
- Skills/commands/agents remain blocked, preventing recursion
- Graceful degradation if setting.json doesn't exist

Generated with SWE-Agent.ai

Co-Authored-By: SWE-Agent.ai <noreply@swe-agent.ai>

* security: pass env via process environment instead of command line

Critical security fix for issue #89:
- Prevents ANTHROPIC_API_KEY leakage in process command line (ps)
- Prevents sensitive values from being logged in wrapper logs

Changes:
1. executor.go:
   - Add SetEnv() method to commandRunner interface
   - realCmd merges env with os.Environ() and sets to cmd.Env
   - All test mocks implement SetEnv()

2. backend.go:
   - Change loadMinimalEnvSettings() to return map[string]string
   - Use os.UserHomeDir() instead of os.Getenv("HOME")
   - Add 1MB file size limit check
   - Only accept string values in env (reject non-strings)
   - Remove --settings parameter (no longer in command line)

3. Tests:
   - Add loadMinimalEnvSettings() unit tests
   - Remove --settings validation (no longer in args)
   - All test mocks implement SetEnv()

Security improvements:
- No sensitive values in argv (safe from ps/logs)
- Type-safe env parsing (string-only)
- File size limit prevents memory issues
- Graceful degradation if setting.json missing

Tests: All pass (30.912s)

Generated with SWE-Agent.ai

Co-Authored-By: SWE-Agent.ai <noreply@swe-agent.ai>

---------

Co-authored-by: SWE-Agent.ai <noreply@swe-agent.ai>

codeagent-wrapper/main_test.go

@@ -255,6 +255,10 @@ func (d *drainBlockingCmd) SetDir(dir string) {
 	d.inner.SetDir(dir)
 }
 
+func (d *drainBlockingCmd) SetEnv(env map[string]string) {
+	d.inner.SetEnv(env)
+}
+
 func (d *drainBlockingCmd) Process() processHandle {
 	return d.inner.Process()
 }
@@ -387,6 +391,8 @@ type fakeCmd struct {
 
 	stderr io.Writer
 
+	env map[string]string
+
 	waitDelay time.Duration
 	waitErr   error
 	startErr  error
@@ -511,6 +517,20 @@ func (f *fakeCmd) SetStderr(w io.Writer) {
 
 func (f *fakeCmd) SetDir(string) {}
 
+func (f *fakeCmd) SetEnv(env map[string]string) {
+	if len(env) == 0 {
+		return
+	}
+	f.mu.Lock()
+	defer f.mu.Unlock()
+	if f.env == nil {
+		f.env = make(map[string]string, len(env))
+	}
+	for k, v := range env {
+		f.env[k] = v
+	}
+}
+
 func (f *fakeCmd) Process() processHandle {
 	if f == nil {
 		return nil
@@ -1549,11 +1569,11 @@ func TestBackendBuildArgs_ClaudeBackend(t *testing.T) {
 	got := backend.BuildArgs(cfg, "todo")
 	want := []string{"-p", "--setting-sources", "", "--output-format", "stream-json", "--verbose", "todo"}
 	if len(got) != len(want) {
-		t.Fatalf("length mismatch")
+		t.Fatalf("args length=%d, want %d: %v", len(got), len(want), got)
 	}
 	for i := range want {
 		if got[i] != want[i] {
-			t.Fatalf("index %d got %s want %s", i, got[i], want[i])
+			t.Fatalf("index %d got %q want %q (args=%v)", i, got[i], want[i], got)
 		}
 	}
 
@@ -1568,19 +1588,15 @@ func TestClaudeBackendBuildArgs_OutputValidation(t *testing.T) {
 	target := "ensure-flags"
 
 	args := backend.BuildArgs(cfg, target)
-	expectedPrefix := []string{"-p", "--setting-sources", "", "--output-format", "stream-json", "--verbose"}
-
-	if len(args) != len(expectedPrefix)+1 {
-		t.Fatalf("args length=%d, want %d", len(args), len(expectedPrefix)+1)
+	want := []string{"-p", "--setting-sources", "", "--output-format", "stream-json", "--verbose", target}
+	if len(args) != len(want) {
+		t.Fatalf("args length=%d, want %d: %v", len(args), len(want), args)
 	}
-	for i, val := range expectedPrefix {
-		if args[i] != val {
-			t.Fatalf("args[%d]=%q, want %q", i, args[i], val)
+	for i := range want {
+		if args[i] != want[i] {
+			t.Fatalf("index %d got %q want %q (args=%v)", i, args[i], want[i], args)
 		}
 	}
-	if args[len(args)-1] != target {
-		t.Fatalf("last arg=%q, want target %q", args[len(args)-1], target)
-	}
 }
 
 func TestBackendBuildArgs_GeminiBackend(t *testing.T) {