feat(cli): default eval fts report to table format on TTYs

When stdout is a terminal, default --format to "table" so the user sees
the lipgloss-styled report out of the box. Pipes, files, and CI fall
back to "markdown" (stable, diff-friendly). --format still overrides.

Author: cpcloud

cmd/micasa/eval.go

@@ -6,6 +6,7 @@ package main
 import (
 	"context"
 	"fmt"
+	"io"
 	"os"
 	"os/signal"
 	"strings"
@@ -81,8 +82,8 @@ provider is a cloud service, the data leaves the machine.`,
 		"deterministic rubric only; skip the LLM judge")
 	cmd.Flags().BoolVar(&opts.noAB, "no-ab", false,
 		"run each question once (FTS on) instead of twice")
-	cmd.Flags().StringVar(&opts.format, "format", "markdown",
-		"report format: markdown or json")
+	cmd.Flags().StringVar(&opts.format, "format", "",
+		"report format: table (default when TTY), markdown, or json")
 	cmd.Flags().StringVar(&opts.output, "output", "",
 		"write report to this file instead of stdout")
 	cmd.Flags().BoolVar(&opts.strict, "strict", false,
@@ -171,8 +172,9 @@ func runEvalFTS(defaultOut interface {
 		return fmt.Errorf("run eval: %w", err)
 	}
 
-	// Write report.
-	out := defaultOut
+	// Write report. Default format: "table" when writing to a TTY,
+	// "markdown" otherwise (pipes, files, CI). --format overrides.
+	out := io.Writer(defaultOut)
 	if opts.output != "" {
 		f, err := os.Create(opts.output)
 		if err != nil {
@@ -181,6 +183,13 @@ func runEvalFTS(defaultOut interface {
 		defer func() { _ = f.Close() }()
 		out = f
 	}
+	if harnessCfg.Format == "" {
+		if writerIsTerminal(out) {
+			harnessCfg.Format = "table"
+		} else {
+			harnessCfg.Format = "markdown"
+		}
+	}
 	if err := ftseval.WriteReport(out, harnessCfg, results); err != nil {
 		return fmt.Errorf("write report: %w", err)
 	}

docs/content/docs/reference/cli.md

@@ -1684,7 +1684,7 @@ micasa eval fts [flags]
 | Flag | Default | Description |
 |------|---------|-------------|
 | `--db` | - | path to a micasa SQLite DB (default: fixture) |
-| `--format` | `markdown` | report format: markdown or json |
+| `--format` | - | report format: table (default when TTY), markdown, or json |
 | `-h`, `--help` | - | help for fts |
 | `--judge-model` | - | model for the LLM judge (default: same as --model) |
 | `--model` | - | override chat model from config |