Add Seriatim trim adapter support

internal/adapters/seriatim/subprocess.go

@@ -111,11 +111,11 @@ func (r *SubprocessRunner) Run(ctx context.Context, req MergeRequest) (MergeResu
 		return MergeResult{}, fmt.Errorf("seriatim report is enabled but report path is missing")
 	}
 
-	args := r.buildArgs(req)
+	args := r.buildMergeArgs(req)
 	env := r.buildEnvOverrides()
 
 	if req.GeneratedConfigPath != "" {
-		if err := r.writeInvocationConfig(req, args); err != nil {
+		if err := r.writeMergeInvocationConfig(req, args); err != nil {
 			return MergeResult{}, fmt.Errorf("write seriatim invocation config %q: %w", req.GeneratedConfigPath, err)
 		}
 	}
@@ -188,7 +188,90 @@ func (r *SubprocessRunner) Run(ctx context.Context, req MergeRequest) (MergeResu
 	}, nil
 }
 
-func (r *SubprocessRunner) buildArgs(req MergeRequest) []string {
+// Trim executes Seriatim trim with deterministic flags and validates output artifacts.
+func (r *SubprocessRunner) Trim(ctx context.Context, req TrimRequest) (TrimResult, error) {
+	if r == nil {
+		return TrimResult{}, fmt.Errorf("seriatim subprocess runner is nil")
+	}
+	if strings.TrimSpace(req.InputTranscriptPath) == "" {
+		return TrimResult{}, fmt.Errorf("seriatim trim input path is required")
+	}
+	if strings.TrimSpace(req.OutputTrimmedPath) == "" {
+		return TrimResult{}, fmt.Errorf("seriatim trim output path is required")
+	}
+	if strings.TrimSpace(req.KeepSelector) == "" {
+		return TrimResult{}, fmt.Errorf("seriatim trim keep selector is required")
+	}
+
+	binary := r.binary
+	if strings.TrimSpace(req.Binary) != "" {
+		binary = strings.TrimSpace(req.Binary)
+	}
+
+	timeout := r.timeout
+	if req.Timeout < 0 {
+		return TrimResult{}, fmt.Errorf("seriatim trim timeout must be >= 0")
+	}
+	if req.Timeout > 0 {
+		timeout = req.Timeout
+	}
+
+	args := buildTrimArgs(req)
+	if req.GeneratedConfigPath != "" {
+		if err := writeTrimInvocationConfig(req, args, binary, timeout); err != nil {
+			return TrimResult{}, fmt.Errorf("write seriatim trim invocation config %q: %w", req.GeneratedConfigPath, err)
+		}
+	}
+
+	runRes, err := subprocess.Run(ctx, subprocess.RunRequest{
+		Executable:    binary,
+		Args:          args,
+		Timeout:       timeout,
+		StdoutLogPath: req.StdoutLogPath,
+		StderrLogPath: req.StderrLogPath,
+	})
+	if err != nil {
+		return TrimResult{
+			OutputTrimmedPath:   req.OutputTrimmedPath,
+			StdoutLogPath:       req.StdoutLogPath,
+			StderrLogPath:       req.StderrLogPath,
+			GeneratedConfigPath: req.GeneratedConfigPath,
+			ExitCode:            runRes.ExitCode,
+			Duration:            runRes.Duration,
+			InvokedBinary:       binary,
+			KeepSelector:        req.KeepSelector,
+		}, fmt.Errorf("run seriatim trim (binary=%q): %w", binary, err)
+	}
+
+	if err := validateJSONFileWithSegments(req.OutputTrimmedPath); err != nil {
+		return TrimResult{
+			OutputTrimmedPath:   req.OutputTrimmedPath,
+			StdoutLogPath:       req.StdoutLogPath,
+			StderrLogPath:       req.StderrLogPath,
+			GeneratedConfigPath: req.GeneratedConfigPath,
+			ExitCode:            runRes.ExitCode,
+			Duration:            runRes.Duration,
+			InvokedBinary:       binary,
+			KeepSelector:        req.KeepSelector,
+		}, fmt.Errorf("validate seriatim trimmed output %q: %w", req.OutputTrimmedPath, err)
+	}
+
+	return TrimResult{
+		OutputTrimmedPath:   req.OutputTrimmedPath,
+		StdoutLogPath:       req.StdoutLogPath,
+		StderrLogPath:       req.StderrLogPath,
+		GeneratedConfigPath: req.GeneratedConfigPath,
+		ExitCode:            runRes.ExitCode,
+		Duration:            runRes.Duration,
+		InvokedBinary:       binary,
+		KeepSelector:        req.KeepSelector,
+		Metadata: map[string]any{
+			"adapter": "seriatim_subprocess",
+		},
+	}, nil
+}
+
+func (r *SubprocessRunner) buildMergeArgs(req MergeRequest) []string {
 	args := []string{"merge"}
 
 	for _, path := range req.InputTranscriptPaths {
@@ -234,10 +317,11 @@ func (r *SubprocessRunner) buildEnvOverrides() map[string]string {
 	return out
 }
 
-func (r *SubprocessRunner) writeInvocationConfig(req MergeRequest, args []string) error {
+func (r *SubprocessRunner) writeMergeInvocationConfig(req MergeRequest, args []string) error {
 	payload := map[string]any{
 		"schema":                 "seriatim.generated.v1",
 		"binary":                 r.binary,
+		"command":                "merge",
 		"args":                   args,
 		"timeout":                r.timeout.String(),
 		"output_schema":          r.outputSchema,
@@ -261,6 +345,29 @@ func (r *SubprocessRunner) writeInvocationConfig(req MergeRequest, args []string
 	return subprocess.WriteYAMLAtomic(req.GeneratedConfigPath, payload, 0o644)
 }
 
+func buildTrimArgs(req TrimRequest) []string {
+	return []string{
+		"trim",
+		"--input-file", req.InputTranscriptPath,
+		"--output-file", req.OutputTrimmedPath,
+		"--keep", req.KeepSelector,
+	}
+}
+
+func writeTrimInvocationConfig(req TrimRequest, args []string, binary string, timeout time.Duration) error {
+	payload := map[string]any{
+		"schema":        "seriatim.generated.v1",
+		"command":       "trim",
+		"binary":        binary,
+		"args":          args,
+		"timeout":       timeout.String(),
+		"input_path":    req.InputTranscriptPath,
+		"output_path":   req.OutputTrimmedPath,
+		"keep_selector": req.KeepSelector,
+	}
+	return subprocess.WriteYAMLAtomic(req.GeneratedConfigPath, payload, 0o644)
+}
+
 func validateJSONFile(path string) error {
 	data, err := os.ReadFile(path)
 	if err != nil {
@@ -272,3 +379,24 @@ func validateJSONFile(path string) error {
 	}
 	return nil
 }
+
+func validateJSONFileWithSegments(path string) error {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return fmt.Errorf("read file: %w", err)
+	}
+
+	var payload map[string]any
+	if err := json.Unmarshal(data, &payload); err != nil {
+		return fmt.Errorf("parse json: %w", err)
+	}
+
+	segments, ok := payload["segments"]
+	if !ok {
+		return fmt.Errorf("top-level segments is required")
+	}
+	if _, ok := segments.([]any); !ok {
+		return fmt.Errorf("top-level segments must be an array")
+	}
+	return nil
+}