feat(mcp): implement cache TTL and finalize Phase 3 roadmap

cmd/dive/cli/internal/mcp/handlers.go

@@ -7,6 +7,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"time"
 
 	lru "github.com/hashicorp/golang-lru/v2"
 	"github.com/mark3labs/mcp-go/mcp"
@@ -18,9 +19,14 @@ import (
 	"github.com/wagoodman/dive/internal/log"
 )
 
+type cachedAnalysis struct {
+	Analysis  *image.Analysis
+	Timestamp time.Time
+}
+
 type toolHandlers struct {
 	opts     options.MCP
-	analyses *lru.Cache[string, *image.Analysis]
+	analyses *lru.Cache[string, cachedAnalysis]
 }
 
 func newToolHandlers(opts options.MCP) *toolHandlers {
@@ -28,7 +34,7 @@ func newToolHandlers(opts options.MCP) *toolHandlers {
 	if cacheSize <= 0 {
 		cacheSize = 10
 	}
-	cache, _ := lru.New[string, *image.Analysis](cacheSize)
+	cache, _ := lru.New[string, cachedAnalysis](cacheSize)
 	return &toolHandlers{
 		opts:     opts,
 		analyses: cache,
@@ -139,11 +145,15 @@ func (h *toolHandlers) getAnalysis(ctx context.Context, imageName string, source
 
 	cacheKey := fmt.Sprintf("%s:%s", sourceStr, imageName)
 
-	if analysis, ok := h.analyses.Get(cacheKey); ok {
-		return analysis, nil
+	if cached, ok := h.analyses.Get(cacheKey); ok {
+		ttl, err := time.ParseDuration(h.opts.CacheTTL)
+		if err == nil && time.Since(cached.Timestamp) < ttl {
+			return cached.Analysis, nil
+		}
+		h.analyses.Remove(cacheKey)
 	}
 
-	log.Infof("Image %s not in cache, analyzing...", imageName)
+	log.Infof("Image %s not in cache or expired, analyzing...", imageName)
 	resolver, err := dive.GetImageResolver(source)
 	if err != nil {
 		return nil, fmt.Errorf("cannot get image resolver: %v", err)
@@ -159,7 +169,10 @@ func (h *toolHandlers) getAnalysis(ctx context.Context, imageName string, source
 		return nil, fmt.Errorf("cannot analyze image: %v", err)
 	}
 
-	h.analyses.Add(cacheKey, analysis)
+	h.analyses.Add(cacheKey, cachedAnalysis{
+		Analysis:  analysis,
+		Timestamp: time.Now(),
+	})
 	return analysis, nil
 }
 

cmd/dive/cli/internal/mcp/handlers_test.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"testing"
+	"time"
 
 	"github.com/mark3labs/mcp-go/mcp"
 	"github.com/stretchr/testify/assert"
@@ -77,11 +78,14 @@ func TestHandlers_SandboxViolation(t *testing.T) {
 
 func TestHandlers_ResourceSummary(t *testing.T) {
 	h := newToolHandlers(options.DefaultMCP())
-	h.analyses.Add("docker:ubuntu:latest", &image.Analysis{
-		Image:       "ubuntu:latest",
-		WastedBytes: 0,
-		SizeBytes:   100,
-		Efficiency:  1.0,
+	h.analyses.Add("docker:ubuntu:latest", cachedAnalysis{
+		Analysis: &image.Analysis{
+			Image:       "ubuntu:latest",
+			WastedBytes: 0,
+			SizeBytes:   100,
+			Efficiency:  1.0,
+		},
+		Timestamp: time.Now(),
 	})
 
 	ctx := context.Background()
@@ -100,6 +104,29 @@ func TestHandlers_ResourceSummary(t *testing.T) {
 	assert.Equal(t, "ubuntu:latest", summary.Image)
 }
 
+func TestHandlers_CacheTTL(t *testing.T) {
+	opts := options.DefaultMCP()
+	opts.CacheTTL = "1ms" // Very short TTL
+	h := newToolHandlers(opts)
+	
+	h.analyses.Add("docker-archive:invalid.tar", cachedAnalysis{
+		Analysis: &image.Analysis{
+			Image: "invalid.tar",
+		},
+		Timestamp: time.Now().Add(-1 * time.Hour), // Way in the past
+	})
+
+	ctx := context.Background()
+	// This should trigger a real analysis attempts because cache is expired
+	imageName := "invalid.tar"
+	sourceStr := "docker-archive"
+	
+	_, err := h.getAnalysis(ctx, imageName, sourceStr)
+	// It should fail to find the file, proving it didn't use the cache
+	assert.Error(t, err) 
+	assert.Contains(t, err.Error(), "no such file or directory")
+}
+
 func TestHandlers_DiffLayers(t *testing.T) {
 	wd, _ := os.Getwd()
 	root := wd

cmd/dive/cli/internal/options/mcp.go

@@ -20,6 +20,8 @@ type MCP struct {
 	Sandbox string `yaml:"sandbox" json:"sandbox" mapstructure:"sandbox"`
 	// CacheSize is the maximum number of analysis results to cache
 	CacheSize int `yaml:"cache-size" json:"cache-size" mapstructure:"cache-size"`
+	// CacheTTL is the time analysis results stay in cache before being considered stale
+	CacheTTL string `yaml:"cache-ttl" json:"cache-ttl" mapstructure:"cache-ttl"`
 }
 
 func DefaultMCP() MCP {
@@ -28,6 +30,7 @@ func DefaultMCP() MCP {
 		Host:      "localhost",
 		Port:      8080,
 		CacheSize: 10,
+		CacheTTL:  "24h",
 	}
 }
 
@@ -37,4 +40,5 @@ func (o *MCP) AddFlags(flags clio.FlagSet) {
 	flags.IntVarP(&o.Port, "port", "", "The port to listen on for the MCP HTTP/SSE server.")
 	flags.StringVarP(&o.Sandbox, "mcp-sandbox", "", "A directory to restrict docker-archive lookups to.")
 	flags.IntVarP(&o.CacheSize, "mcp-cache-size", "", "The maximum number of analysis results to cache.")
+	flags.StringVarP(&o.CacheTTL, "mcp-cache-ttl", "", "The duration to keep analysis results in cache (e.g. 1h, 30m).")
 }