Name request log actions so they say what they mean (closes #229)

Rename too_large, rate_limited, rule_blocked and denied, and split banned
into temporarily_banned and permanently_banned by whether the ban runs out.
A request that makes a ban permanent gets permanently_banned. A ban the
request itself makes gets the value for that ban, and in observe mode
would_action names the ban enforce mode would have made.

The offence kind rule_blocked follows, as a metric label and a key in
clients.json.

Model: opus-5-5

internal/discriminator/observe_test.go

@@ -14,6 +14,70 @@ import (
 // observe is the value of SWW_MODE for observe mode.
 const observe = "observe"
 
+func TestBanActionSaysWhetherTheBanRunsOut(t *testing.T) {
+	t.Parallel()
+
+	const trapPath = "/wp-login.php"
+
+	for _, tc := range []struct {
+		name  string
+		cause string
+		// endsIn is how long after the request the ban ends: negative for a
+		// ban that has ended, and zero for a permanent ban.
+		endsIn time.Duration
+		path   string
+		want   string
+	}{
+		{
+			"temporary ban", bans.CauseAdmin, time.Hour, "/",
+			requestlog.ActionTemporarilyBanned,
+		},
+		{"permanent ban", bans.CauseAdmin, 0, "/", requestlog.ActionPermanentlyBanned},
+		{
+			"request that makes a ban permanent", bans.CauseAttack, time.Hour, "/",
+			requestlog.ActionPermanentlyBanned,
+		},
+		{
+			"trap path after an attack ban ended", bans.CauseAttack, -time.Hour,
+			trapPath, requestlog.ActionPermanentlyBanned,
+		},
+		{
+			"first trap path after another ban ended", bans.CauseAdmin, -time.Hour,
+			trapPath, requestlog.ActionTemporarilyBanned,
+		},
+	} {
+		for _, modeValue := range []string{"enforce", observe} {
+			t.Run(tc.name+" in "+modeValue, func(t *testing.T) {
+				t.Parallel()
+
+				s, clk, server := startWithClock(t, "", map[string]string{
+					trapPaths: trapPathList, mode: modeValue,
+				})
+
+				ban := bans.Ban{
+					Netblock: netip.MustParsePrefix(client + "/32"),
+					Start:    clk.Now().Add(-2 * time.Hour),
+					Cause:    tc.cause,
+				}
+				if tc.endsIn != 0 {
+					ban.Expires = clk.Now().Add(tc.endsIn)
+				}
+
+				server.Ledger.Load([]bans.Ban{ban})
+
+				if modeValue == observe {
+					line := s.request(client, tc.path, http.StatusOK, requestlog.ActionForward)
+					wantWouldAction(t, line, tc.want)
+
+					return
+				}
+
+				s.request(client, tc.path, http.StatusForbidden, tc.want)
+			})
+		}
+	}
+}
+
 func TestObserveModeNamesTheHeuristicThatWouldHaveRefused(t *testing.T) {
 	t.Parallel()
 
@@ -22,7 +86,7 @@ func TestObserveModeNamesTheHeuristicThatWouldHaveRefused(t *testing.T) {
 	})
 
 	line := s.get(client, http.StatusOK, requestlog.ActionForward)
-	wantWouldAction(t, line, requestlog.ActionDenied)
+	wantWouldAction(t, line, requestlog.ActionClientDenied)
 	wantHeuristic(t, line, "deny_nets", `{"netblock": "`+client+`/32"}`)
 }
 
@@ -69,10 +133,10 @@ func TestObserveModeForwardsWhatEnforceModeRefuses(t *testing.T) {
 			s.get(fromDE, http.StatusOK, requestlog.ActionForward)
 
 			for _, sent := range []struct{ from, refusal string }{
-				{denied, requestlog.ActionDenied},
-				{banned, requestlog.ActionBanned},
-				{fromKP, requestlog.ActionDenied},
-				{fromDE, requestlog.ActionRateLimited},
+				{denied, requestlog.ActionClientDenied},
+				{banned, requestlog.ActionTemporarilyBanned},
+				{fromKP, requestlog.ActionClientDenied},
+				{fromDE, requestlog.ActionClientIsRateLimited},
 			} {
 				if !tc.observe {
 					line := s.get(sent.from, http.StatusForbidden, sent.refusal)
@@ -110,7 +174,7 @@ func TestObserveModeMakesNoBanAndKeepsTheBansItHas(t *testing.T) {
 
 	for range 2 {
 		line := s.get(client, http.StatusOK, requestlog.ActionForward)
-		wantWouldAction(t, line, requestlog.ActionRateLimited)
+		wantWouldAction(t, line, requestlog.ActionClientIsRateLimited)
 
 		if line.LimitHit != minute || line.Offence != requestlog.OffenceLimit ||
 			line.BanExpires != "" {
@@ -123,7 +187,7 @@ func TestObserveModeMakesNoBanAndKeepsTheBansItHas(t *testing.T) {
 	// The ban read from bans.json refuses nothing, and so counts no
 	// refusal in its notes, but is kept.
 	line := s.get(otherClient, http.StatusOK, requestlog.ActionForward)
-	wantWouldAction(t, line, requestlog.ActionBanned)
+	wantWouldAction(t, line, requestlog.ActionTemporarilyBanned)
 
 	if line.BanExpires != requestlog.FormatTime(kept.Expires) {
 		t.Errorf("log line has ban_expires %q, want %s", line.BanExpires,