Fix Title Length

e2e/testdata/cassettes/TestRuntime_Mistral_Basic.yaml

@@ -28,7 +28,7 @@ interactions:
     proto_minor: 1
     content_length: 0
     host: api.mistral.ai
-    body: "{\"messages\":[{\"content\":\"You are a helpful AI assistant that generates concise, descriptive titles for conversations. You will be given a conversation history and asked to create a title that captures the main topic.\",\"role\":\"system\"},{\"content\":\"Based on the following message a user sent to an AI assistant, generate a short, descriptive title (maximum 50 characters) that captures the main topic or purpose of the conversation. Return ONLY the title text, nothing else.\\n\\nUser message: What's 2+2?\\n\\n\",\"role\":\"user\"}],\"model\":\"mistral-small\",\"stream_options\":{\"include_usage\":true},\"stream\":true}"
+    body: "{\"messages\":[{\"content\":\"You are a helpful AI assistant that generates concise, descriptive titles for conversations. You will be given a conversation history and asked to create a title that captures the main topic.\",\"role\":\"system\"},{\"content\":\"Based on the following message a user sent to an AI assistant, generate a short, descriptive title (maximum 50 characters) that captures the main topic or purpose of the conversation. Return ONLY the title text, nothing else.\\n\\nUser message: What's 2+2?\\n\\n\",\"role\":\"user\"}],\"model\":\"mistral-small\",\"max_tokens\":100,\"stream_options\":{\"include_usage\":true},\"stream\":true}"
     url: https://api.mistral.ai/v1/chat/completions
     method: POST
   response:

e2e/testdata/cassettes/TestRuntime_OpenAI_Basic.yaml

@@ -8,7 +8,7 @@ interactions:
     proto_minor: 1
     content_length: 0
     host: api.openai.com
-    body: "{\"messages\":[{\"content\":\"You are a helpful AI assistant that generates concise, descriptive titles for conversations. You will be given a conversation history and asked to create a title that captures the main topic.\",\"role\":\"system\"},{\"content\":\"Based on the following message a user sent to an AI assistant, generate a short, descriptive title (maximum 50 characters) that captures the main topic or purpose of the conversation. Return ONLY the title text, nothing else.\\n\\nUser message: What's 2+2?\\n\\n\",\"role\":\"user\"}],\"model\":\"gpt-3.5-turbo\",\"stream_options\":{\"include_usage\":true},\"stream\":true}"
+    body: "{\"messages\":[{\"content\":\"You are a helpful AI assistant that generates concise, descriptive titles for conversations. You will be given a conversation history and asked to create a title that captures the main topic.\",\"role\":\"system\"},{\"content\":\"Based on the following message a user sent to an AI assistant, generate a short, descriptive title (maximum 50 characters) that captures the main topic or purpose of the conversation. Return ONLY the title text, nothing else.\\n\\nUser message: What's 2+2?\\n\\n\",\"role\":\"user\"}],\"model\":\"gpt-3.5-turbo\",\"max_tokens\":100,\"stream_options\":{\"include_usage\":true},\"stream\":true}"
     url: https://api.openai.com/v1/chat/completions
     method: POST
   response:

pkg/model/provider/clone.go

@@ -18,7 +18,18 @@ func CloneWithOptions(ctx context.Context, base Provider, opts ...options.Opt) P
 	mergedOpts := append(baseOpts, opts...)
 	mergedOpts = append(mergedOpts, options.WithGeneratingTitle())
 
-	clone, err := New(ctx, &config.ModelConfig, config.Env, mergedOpts...)
+	// Apply max_tokens override if present in options
+	// We need to apply it to the ModelConfig itself since that's what providers use
+	modelConfig := config.ModelConfig
+	for _, opt := range mergedOpts {
+		tempOpts := &options.ModelOptions{}
+		opt(tempOpts)
+		if maxTokens := tempOpts.MaxTokens(); maxTokens != nil {
+			modelConfig.MaxTokens = *maxTokens
+		}
+	}
+
+	clone, err := New(ctx, &modelConfig, config.Env, mergedOpts...)
 	if err != nil {
 		slog.Debug("Failed to clone provider; using base provider", "error", err, "id", base.ID())
 		return base

pkg/model/provider/options/options.go

@@ -8,6 +8,7 @@ type ModelOptions struct {
 	gateway          string
 	structuredOutput *latest.StructuredOutput
 	generatingTitle  bool
+	maxTokens        *int
 }
 
 func (c *ModelOptions) Gateway() string {
@@ -22,6 +23,10 @@ func (c *ModelOptions) GeneratingTitle() bool {
 	return c.generatingTitle
 }
 
+func (c *ModelOptions) MaxTokens() *int {
+	return c.maxTokens
+}
+
 type Opt func(*ModelOptions)
 
 func WithGateway(gateway string) Opt {
@@ -42,6 +47,12 @@ func WithGeneratingTitle() Opt {
 	}
 }
 
+func WithMaxTokens(maxTokens int) Opt {
+	return func(cfg *ModelOptions) {
+		cfg.maxTokens = &maxTokens
+	}
+}
+
 // FromModelOptions converts a concrete ModelOptions value into a slice of
 // Opt configuration functions. Later Opts override earlier ones when applied.
 func FromModelOptions(m ModelOptions) []Opt {
@@ -55,5 +66,8 @@ func FromModelOptions(m ModelOptions) []Opt {
 	if m.generatingTitle {
 		out = append(out, WithGeneratingTitle())
 	}
+	if m.maxTokens != nil {
+		out = append(out, WithMaxTokens(*m.maxTokens))
+	}
 	return out
 }

pkg/runtime/runtime.go

@@ -1295,6 +1295,18 @@ func (r *LocalRuntime) handleHandoff(ctx context.Context, sess *session.Session,
 	}, nil
 }
 
+// truncateTitle truncates a title to maxLength characters, adding an ellipsis if needed
+func truncateTitle(title string, maxLength int) string {
+	if len(title) <= maxLength {
+		return title
+	}
+	// Ensure we have room for the ellipsis
+	if maxLength < 3 {
+		return "..."
+	}
+	return title[:maxLength-3] + "..."
+}
+
 // generateSessionTitle generates a title for the session based on the first user message
 func (r *LocalRuntime) generateSessionTitle(ctx context.Context, sess *session.Session, events chan Event) {
 	slog.Debug("Generating title for session", "session_id", sess.ID)
@@ -1309,7 +1321,7 @@ func (r *LocalRuntime) generateSessionTitle(ctx context.Context, sess *session.S
 	systemPrompt := "You are a helpful AI assistant that generates concise, descriptive titles for conversations. You will be given a conversation history and asked to create a title that captures the main topic."
 	userPrompt := fmt.Sprintf("Based on the following message a user sent to an AI assistant, generate a short, descriptive title (maximum 50 characters) that captures the main topic or purpose of the conversation. Return ONLY the title text, nothing else.\n\nUser message: %s\n\n", firstUserMessage)
 
-	titleModel := provider.CloneWithOptions(ctx, r.CurrentAgent().Model(), options.WithStructuredOutput(nil))
+	titleModel := provider.CloneWithOptions(ctx, r.CurrentAgent().Model(), options.WithStructuredOutput(nil), options.WithMaxTokens(100))
 	newTeam := team.New(
 		team.WithID("title-generator"),
 		team.WithAgents(agent.New("root", systemPrompt, agent.WithModel(titleModel))),
@@ -1337,6 +1349,8 @@ func (r *LocalRuntime) generateSessionTitle(ctx context.Context, sess *session.S
 	if title == "" {
 		return
 	}
+	// Truncate title to 50 characters with ellipsis if needed
+	title = truncateTitle(title, 50)
 	sess.Title = title
 	slog.Debug("Generated session title", "session_id", sess.ID, "title", title)
 	events <- SessionTitle(sess.ID, title, r.currentAgent)

pkg/runtime/runtime_test.go

@@ -879,3 +879,66 @@ func TestEmitStartupInfo(t *testing.T) {
 	// Should be empty due to deduplication
 	require.Empty(t, collectedEvents2, "EmitStartupInfo should not emit duplicate events")
 }
+
+func TestTruncateTitle(t *testing.T) {
+	tests := []struct {
+		name      string
+		title     string
+		maxLength int
+		expected  string
+	}{
+		{
+			name:      "title shorter than max length",
+			title:     "Short title",
+			maxLength: 50,
+			expected:  "Short title",
+		},
+		{
+			name:      "title exactly at max length",
+			title:     "This is exactly fifty characters in length now.",
+			maxLength: 50,
+			expected:  "This is exactly fifty characters in length now.",
+		},
+		{
+			name:      "title longer than max length",
+			title:     "This is a very long title that exceeds the maximum character limit",
+			maxLength: 50,
+			expected:  "This is a very long title that exceeds the maxi...",
+		},
+		{
+			name:      "very short max length",
+			title:     "Any title",
+			maxLength: 5,
+			expected:  "An...",
+		},
+		{
+			name:      "max length less than 3",
+			title:     "Any title",
+			maxLength: 2,
+			expected:  "...",
+		},
+		{
+			name:      "empty title",
+			title:     "",
+			maxLength: 50,
+			expected:  "",
+		},
+		{
+			name:      "title with unicode characters",
+			title:     "こんにちは、これは日本語のタイトルです。とても長いタイトルなので切り捨てられるはずです。",
+			maxLength: 50,
+			expected:  "こんにちは、これは日本語のタイトルです。とても長いタイトルなので切り捨てられるはずです。"[:47] + "...",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := truncateTitle(tt.title, tt.maxLength)
+			require.Equal(t, tt.expected, result)
+			// Only check length constraint if maxLength >= 3 (otherwise ellipsis alone is 3 chars)
+			if tt.maxLength >= 3 {
+				require.LessOrEqual(t, len(result), tt.maxLength)
+			}
+		})
+	}
+}