feat: SupportsInteractivePTY() flag per adapter

Only Claude Code uses interactive PTY (vt10x) for now — its screen
layout is validated. Copilot, Codex, Gemini, Cursor use non-interactive
exec or JSON streaming until their interactive PTY is refined.

Stream() resolution order:
1. Interactive PTY (if SupportsInteractivePTY) — multi-turn
2. JSON streaming (if StreamingArgs) — structured events
3. Non-interactive exec — simplest fallback

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: intel352

genkit/pty_adapters.go

@@ -81,6 +81,8 @@ func (ClaudeCodeAdapter) ParseResponse(raw string) string {
 	return parseResponseDefault(raw)
 }
 
+func (ClaudeCodeAdapter) SupportsInteractivePTY() bool { return true }
+
 func (ClaudeCodeAdapter) StreamingArgs(msg string) []string {
 	return []string{"-p", msg, "--output-format", "stream-json", "--verbose"}
 }
@@ -299,12 +301,20 @@ func (CursorCLIAdapter) ParseResponse(raw string) string {
 // StreamingArgs/ParseStreamEvent for adapters without JSON streaming support.
 // They use the streamFallback path (non-interactive exec).
 
+// Copilot uses non-interactive fallback for now — interactive PTY response
+// extraction needs refinement for Copilot's specific screen layout.
 func (CopilotCLIAdapter) StreamingArgs(_ string) []string          { return nil }
 func (CopilotCLIAdapter) ParseStreamEvent(_ string) (string, bool) { return "", false }
 
+// SupportsInteractivePTY returns false — Copilot should use non-interactive exec.
+func (CopilotCLIAdapter) SupportsInteractivePTY() bool { return false }
+
+func (CodexCLIAdapter) SupportsInteractivePTY() bool             { return false }
 func (CodexCLIAdapter) StreamingArgs(_ string) []string          { return nil }
 func (CodexCLIAdapter) ParseStreamEvent(_ string) (string, bool) { return "", false }
 
+func (GeminiCLIAdapter) SupportsInteractivePTY() bool { return false }
+
 func (GeminiCLIAdapter) StreamingArgs(msg string) []string {
 	return []string{"-p", msg, "--output-format", "stream-json"}
 }
@@ -328,5 +338,6 @@ func (GeminiCLIAdapter) ParseStreamEvent(line string) (string, bool) {
 	return "", false
 }
 
+func (CursorCLIAdapter) SupportsInteractivePTY() bool             { return false }
 func (CursorCLIAdapter) StreamingArgs(_ string) []string          { return nil }
 func (CursorCLIAdapter) ParseStreamEvent(_ string) (string, bool) { return "", false }

genkit/pty_provider.go

@@ -40,6 +40,10 @@ type CLIAdapter interface {
 	// Returns the text content and true if the line contained assistant text,
 	// or empty string and false if the line should be skipped.
 	ParseStreamEvent(line string) (string, bool)
+	// SupportsInteractivePTY returns true if the tool's interactive TUI is
+	// compatible with vt10x screen reading. Tools that return false skip the
+	// interactive path and go straight to JSON streaming or non-interactive exec.
+	SupportsInteractivePTY() bool
 }
 
 // ptyProvider implements provider.Provider by driving a CLI tool via PTY.
@@ -108,19 +112,26 @@ func (p *ptyProvider) Stream(ctx context.Context, messages []provider.Message, _
 	go func() {
 		defer close(ch)
 
-		// Primary: interactive PTY session via vt10x virtual terminal.
-		if err := p.streamInteractive(ctx, msg, ch); err != nil {
-			// If interactive fails, try JSON streaming as fallback.
-			if args := p.adapter.StreamingArgs(msg); args != nil {
-				if jsonErr := p.streamJSON(ctx, args, ch); jsonErr == nil {
-					return
-				}
+		// Resolution order:
+		// 1. Interactive PTY (if adapter supports it) — multi-turn session context
+		// 2. JSON streaming (if adapter provides StreamingArgs) — structured events
+		// 3. Non-interactive exec — simplest fallback
+
+		if p.adapter.SupportsInteractivePTY() {
+			if err := p.streamInteractive(ctx, msg, ch); err == nil {
+				return
 			}
-			// Last resort: non-interactive exec.
-			if fallbackErr := p.streamFallback(ctx, msg, ch); fallbackErr != nil {
-				ch <- provider.StreamEvent{Type: "error", Error: err.Error()}
+		}
+
+		if args := p.adapter.StreamingArgs(msg); args != nil {
+			if err := p.streamJSON(ctx, args, ch); err == nil {
+				return
 			}
 		}
+
+		if err := p.streamFallback(ctx, msg, ch); err != nil {
+			ch <- provider.StreamEvent{Type: "error", Error: err.Error()}
+		}
 	}()
 
 	return ch, nil

genkit/pty_provider_test.go

@@ -49,6 +49,7 @@ func (m *mockCLIAdapter) ParseResponse(raw string) string {
 	return stripANSI(raw)
 }
 
+func (m *mockCLIAdapter) SupportsInteractivePTY() bool             { return false }
 func (m *mockCLIAdapter) StreamingArgs(_ string) []string          { return nil }
 func (m *mockCLIAdapter) ParseStreamEvent(_ string) (string, bool) { return "", false }