fix: order session providers by usage frequency instead of alphabetically

The AI Sessions page Provider column displayed the wrong provider when a
session contained interceptions from multiple providers. This happened
because providers were aggregated with ARRAY_AGG(DISTINCT ... ORDER BY
provider), which sorts alphabetically. Since 'anthropic' < 'openai', a
single Anthropic Haiku title-generation interception would push
Anthropic to index 0, even when the session was primarily an OpenAI
chat.

Replace the alphabetical ARRAY_AGG with a subquery that groups providers
by count and orders them most-frequent-first (with alphabetical as
tiebreaker). The frontend already displays providers[0], so the primary
chat provider now appears correctly.

Fixes: AIGOV-403

coderd/database/queries.sql.go

@@ -2125,7 +2125,20 @@ LEFT JOIN LATERAL (
 	SELECT
 		(ARRAY_AGG(ai.client ORDER BY ai.started_at, ai.id))[1] AS client,
 		(ARRAY_AGG(ai.metadata ORDER BY ai.started_at, ai.id))[1] AS metadata,
-		ARRAY_AGG(DISTINCT ai.provider ORDER BY ai.provider) AS providers,
+		-- Order providers by usage frequency (most-used first) so the
+		-- "primary" chat provider appears at index 0 even when a
+		-- secondary provider (e.g. Anthropic Haiku for title generation)
+		-- is also present in the session.
+		(SELECT array_agg(sub.provider ORDER BY sub.cnt DESC, sub.provider)
+		 FROM (
+		   SELECT ai2.provider, COUNT(*) AS cnt
+		   FROM aibridge_interceptions ai2
+		   WHERE ai2.session_id = sp.session_id
+		     AND ai2.initiator_id = sp.initiator_id
+		     AND ai2.ended_at IS NOT NULL
+		   GROUP BY ai2.provider
+		 ) sub
+		) AS providers,
 		ARRAY_AGG(DISTINCT ai.model ORDER BY ai.model) AS models,
 		ARRAY_AGG(ai.id) AS interception_ids
 	FROM aibridge_interceptions ai

coderd/database/queries/aibridge.sql

@@ -591,7 +591,20 @@ LEFT JOIN LATERAL (
 	SELECT
 		(ARRAY_AGG(ai.client ORDER BY ai.started_at, ai.id))[1] AS client,
 		(ARRAY_AGG(ai.metadata ORDER BY ai.started_at, ai.id))[1] AS metadata,
-		ARRAY_AGG(DISTINCT ai.provider ORDER BY ai.provider) AS providers,
+		-- Order providers by usage frequency (most-used first) so the
+		-- "primary" chat provider appears at index 0 even when a
+		-- secondary provider (e.g. Anthropic Haiku for title generation)
+		-- is also present in the session.
+		(SELECT array_agg(sub.provider ORDER BY sub.cnt DESC, sub.provider)
+		 FROM (
+		   SELECT ai2.provider, COUNT(*) AS cnt
+		   FROM aibridge_interceptions ai2
+		   WHERE ai2.session_id = sp.session_id
+		     AND ai2.initiator_id = sp.initiator_id
+		     AND ai2.ended_at IS NOT NULL
+		   GROUP BY ai2.provider
+		 ) sub
+		) AS providers,
 		ARRAY_AGG(DISTINCT ai.model ORDER BY ai.model) AS models,
 		ARRAY_AGG(ai.id) AS interception_ids
 	FROM aibridge_interceptions ai

enterprise/coderd/aibridge_test.go

@@ -840,6 +840,49 @@ func TestAIBridgeListSessions(t *testing.T) {
 		require.ElementsMatch(t, []string{"claude-4", "gpt-4"}, s4.Models)
 	})
 
+	// Regression test for https://linear.app/codercom/issue/AIGOV-403
+	t.Run("ProviderOrderByFrequency", func(t *testing.T) {
+		t.Parallel()
+		client, db, firstUser := coderdenttest.NewWithDatabase(t, aibridgeOpts(t))
+		ctx := testutil.Context(t, testutil.WaitLong)
+
+		now := dbtime.Now()
+
+		// Simulate an OpenAI chat session with 3 OpenAI interceptions
+		// and 1 Anthropic interception (title generation via Haiku).
+		for i := range 3 {
+			endedAt := now.Add(time.Duration(i+1) * time.Minute)
+			dbgen.AIBridgeInterception(t, db, database.InsertAIBridgeInterceptionParams{
+				InitiatorID:     firstUser.UserID,
+				Provider:        "openai",
+				Model:           "gpt-4o",
+				StartedAt:       now.Add(time.Duration(i) * time.Minute),
+				Client:          sql.NullString{String: "cursor", Valid: true},
+				ClientSessionID: sql.NullString{String: "session-freq", Valid: true},
+			}, &endedAt)
+		}
+		// Single Anthropic title-generation interception in the same session.
+		haikuEnded := now.Add(30 * time.Second)
+		dbgen.AIBridgeInterception(t, db, database.InsertAIBridgeInterceptionParams{
+			InitiatorID:     firstUser.UserID,
+			Provider:        "anthropic",
+			Model:           "claude-haiku-4-5",
+			StartedAt:       now.Add(10 * time.Second),
+			Client:          sql.NullString{String: "cursor", Valid: true},
+			ClientSessionID: sql.NullString{String: "session-freq", Valid: true},
+		}, &haikuEnded)
+
+		//nolint:gocritic // Owner role is irrelevant here.
+		res, err := client.AIBridgeListSessions(ctx, codersdk.AIBridgeListSessionsFilter{})
+		require.NoError(t, err)
+		require.Len(t, res.Sessions, 1)
+
+		s := res.Sessions[0]
+		require.Equal(t, "session-freq", s.ID)
+		// OpenAI must be first because it has more interceptions.
+		require.Equal(t, []string{"openai", "anthropic"}, s.Providers)
+	})
+
 	t.Run("Pagination", func(t *testing.T) {
 		t.Parallel()
 		client, db, firstUser := coderdenttest.NewWithDatabase(t, aibridgeOpts(t))