fix: redact sensitive headers in httplog + restore headless logging

P0 #1 — HTTP traffic logger captured Authorization, Cookie, Set-Cookie,
X-Api-Key, X-Auth-Token, X-Csrf-Token, Proxy-Authorization, X-Access-Token
verbatim into log entries (file 0600 + UI subscribers). Bearer tokens
and session cookies were ending up on disk whenever httpLog.includeHeaders
was enabled.

flattenHeaders now redacts:
  - the explicit list above (case-insensitive via http.CanonicalHeaderKey)
  - any header name containing 'token', 'secret', 'password', 'apikey'
Header names remain visible; values become [REDACTED].
Redaction is unconditional and on-by-default — no opt-out flag. Users
who want raw headers can use tcpdump.

P0 #6 — Headless mode without -v silently routed both structured and
stdlib logs to io.Discard. A daemon under launchd/systemd had no way to
report errors. Headless now defaults log destination to os.Stderr; -v
controls only the level (debug vs info). TUI-quiet path is preserved.

Tests in internal/httplog/redact_test.go cover all explicit names,
substring patterns, and case variants.

cmd/kportal/main.go

@@ -102,16 +102,33 @@ func main() {
 	}
 
 	// Initialize structured logger
+	//
+	// Output destination depends on run mode, NOT on the -v flag:
+	//   - headless mode: always stderr, so daemons under launchd/systemd/journald
+	//     can surface startup and runtime errors. Without this the daemon would
+	//     fail silently and operators have no way to diagnose it.
+	//   - TUI (interactive) mode: stderr would corrupt the bubbletea UI, so we
+	//     route to io.Discard. Verbose TUI is not supported here either; -v in
+	//     interactive mode upgrades to the simple table UI further down.
+	//
+	// The -v flag only controls log *level* (debug vs info), never destination.
 	var logLevel logger.Level
 	var logFmt logger.Format
 	var logOutput io.Writer
 
 	if *verbose {
 		logLevel = logger.LevelDebug
-		logOutput = os.Stderr
 	} else {
 		logLevel = logger.LevelInfo
-		logOutput = io.Discard // Silence logger in non-verbose/headless mode to prevent UI corruption
+	}
+
+	if *headless || *verbose {
+		// Headless daemons must always emit logs so operators can see failures.
+		// Verbose mode (with or without TUI) also goes to stderr.
+		logOutput = os.Stderr
+	} else {
+		// Interactive TUI mode: silence logger to avoid corrupting bubbletea UI.
+		logOutput = io.Discard
 	}
 
 	switch *logFormat {
@@ -179,14 +196,22 @@ func main() {
 		os.Exit(0)
 	}
 
-	if !*verbose {
+	// Configure stdlib log destination using the same rule as the structured
-		// In interactive mode, disable ALL logging to avoid interfering with bubbletea UI
+	// logger: only the bubbletea TUI path needs total silence. Headless mode
+	// keeps stderr so daemonised runs surface errors to journald/launchd.
+	switch {
+	case *verbose:
+		// Verbose mode - enable standard log formatting on stderr (default)
+		log.SetFlags(log.LstdFlags | log.Lshortfile)
+	case *headless:
+		// Headless mode without -v: keep stderr (default writer) but use plain
+		// timestamps so journald-style log collectors show readable lines.
+		log.SetFlags(log.LstdFlags)
+	default:
+		// Interactive bubbletea mode: silence stdlib log to avoid UI corruption.
 		log.SetOutput(io.Discard)
 		log.SetPrefix("")
 		log.SetFlags(0)
-	} else {
-		// Verbose mode - enable standard log formatting
-		log.SetFlags(log.LstdFlags | log.Lshortfile)
 	}
 
 	// Load configuration

internal/httplog/proxy.go

@@ -339,11 +339,70 @@ func (p *Proxy) logError(req *http.Request, err error) {
 	_ = p.logger.Log(entry)
 }
 
-// flattenHeaders converts http.Header to map[string]string.
+// redactedHeaderNames is the set of header names whose values are always
-// Pre-allocates the map with the exact size needed to avoid reallocations.
+// redacted before being captured into log entries. Comparison is
+// case-insensitive (canonical MIME header form is used as the key).
+//
+// Redaction is unconditional and on-by-default as a defense-in-depth measure:
+// these headers commonly carry bearer tokens, session cookies, API keys, or
+// other credentials that must never be persisted to disk or surfaced to the
+// UI. Users who genuinely need raw header capture should use a dedicated
+// packet-capture tool (e.g. tcpdump) instead.
+var redactedHeaderNames = map[string]struct{}{
+	"Authorization":       {},
+	"Proxy-Authorization": {},
+	"Cookie":              {},
+	"Set-Cookie":          {},
+	"X-Api-Key":           {},
+	"X-Auth-Token":        {},
+	"X-Csrf-Token":        {},
+	"X-Access-Token":      {},
+}
+
+// redactedHeaderSubstrings is a list of lowercase substrings that, when
+// found anywhere in a header name (case-insensitive), trigger redaction.
+// This catches custom or vendor-specific sensitive headers without needing
+// to enumerate every variant.
+var redactedHeaderSubstrings = []string{
+	"token",
+	"secret",
+	"password",
+	"apikey",
+}
+
+// redactedValue is the placeholder written in place of any sensitive header
+// value. The header name itself is preserved so operators can see which
+// sensitive headers were present without leaking their contents.
+const redactedValue = "[REDACTED]"
+
+// shouldRedactHeader reports whether the given header name should have its
+// value redacted before being recorded. The check is case-insensitive and
+// covers both the explicit name list and the substring patterns.
+func shouldRedactHeader(name string) bool {
+	if _, ok := redactedHeaderNames[http.CanonicalHeaderKey(name)]; ok {
+		return true
+	}
+	lower := strings.ToLower(name)
+	for _, sub := range redactedHeaderSubstrings {
+		if strings.Contains(lower, sub) {
+			return true
+		}
+	}
+	return false
+}
+
+// flattenHeaders converts http.Header to map[string]string, redacting the
+// values of any sensitive headers (see redactedHeaderNames /
+// redactedHeaderSubstrings) so that credentials never reach the log file or
+// UI subscribers. Pre-allocates the map with the exact size needed to avoid
+// reallocations.
 func flattenHeaders(h http.Header) map[string]string {
 	result := make(map[string]string, len(h))
 	for k, v := range h {
+		if shouldRedactHeader(k) {
+			result[k] = redactedValue
+			continue
+		}
 		result[k] = strings.Join(v, ", ")
 	}
 	return result

internal/httplog/redact_test.go

@@ -0,0 +1,102 @@
+package httplog
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// TestFlattenHeaders_RedactsSensitive verifies that flattenHeaders replaces
+// the values of known sensitive headers with the [REDACTED] placeholder while
+// preserving the header name and leaving benign headers untouched. Covers
+// the explicit name list, case-insensitive matching, and the substring-based
+// fallback patterns ("token", "secret", "password", "apikey").
+func TestFlattenHeaders_RedactsSensitive(t *testing.T) {
+	h := http.Header{
+		// Explicit list (canonical casing)
+		"Authorization":       []string{"Bearer eyJhbGciOiJIUzI1NiJ9.payload.sig"},
+		"Proxy-Authorization": []string{"Basic dXNlcjpwYXNz"},
+		"Cookie":              []string{"session=abc123; csrf=xyz"},
+		"Set-Cookie":          []string{"session=abc123; HttpOnly"},
+		"X-Api-Key":           []string{"sk_live_deadbeef"},
+		"X-Auth-Token":        []string{"tok_supersecret"},
+		"X-Csrf-Token":        []string{"csrf_random_value"},
+		"X-Access-Token":      []string{"at_anothersecret"},
+
+		// Substring matches (case-insensitive)
+		"X-Refresh-Token":  []string{"rt_value"},
+		"My-Secret-Header": []string{"shh"},
+		"X-User-Password":  []string{"hunter2"},
+		"X-Custom-Apikey":  []string{"key_value"},
+
+		// Benign headers must be preserved verbatim
+		"Content-Type": []string{"application/json"},
+		"Accept":       []string{"text/html", "application/json"},
+		"User-Agent":   []string{"kportal-test/1.0"},
+	}
+
+	result := flattenHeaders(h)
+
+	redactedHeaders := []string{
+		"Authorization",
+		"Proxy-Authorization",
+		"Cookie",
+		"Set-Cookie",
+		"X-Api-Key",
+		"X-Auth-Token",
+		"X-Csrf-Token",
+		"X-Access-Token",
+		"X-Refresh-Token",
+		"My-Secret-Header",
+		"X-User-Password",
+		"X-Custom-Apikey",
+	}
+	for _, name := range redactedHeaders {
+		got, ok := result[name]
+		assert.Truef(t, ok, "expected redacted header %q to remain present in output", name)
+		assert.Equalf(t, "[REDACTED]", got, "expected header %q value to be redacted", name)
+	}
+
+	// Benign headers should be untouched.
+	assert.Equal(t, "application/json", result["Content-Type"])
+	assert.Equal(t, "text/html, application/json", result["Accept"])
+	assert.Equal(t, "kportal-test/1.0", result["User-Agent"])
+
+	// And no benign value should leak the redaction marker (sanity check).
+	for _, name := range []string{"Content-Type", "Accept", "User-Agent"} {
+		assert.NotEqualf(t, "[REDACTED]", result[name], "benign header %q must not be redacted", name)
+	}
+}
+
+// TestShouldRedactHeader_CaseInsensitive verifies that the case-insensitive
+// match logic catches lowercased / mixed-case variants of the redaction list.
+func TestShouldRedactHeader_CaseInsensitive(t *testing.T) {
+	cases := []struct {
+		name string
+		want bool
+	}{
+		{"authorization", true},
+		{"AUTHORIZATION", true},
+		{"AuThOrIzAtIoN", true},
+		{"cookie", true},
+		{"set-cookie", true},
+		{"x-api-key", true},
+		{"X-CUSTOM-TOKEN", true},
+		{"x-app-Secret", true},
+		{"My_Password_Header", true},
+		{"x-vendor-APIKEY", true},
+
+		// Non-sensitive
+		{"Content-Type", false},
+		{"Accept", false},
+		{"User-Agent", false},
+		{"X-Request-Id", false},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			assert.Equal(t, tc.want, shouldRedactHeader(tc.name))
+		})
+	}
+}