feat(config): surface matches hidden by extension filters

README.md

@@ -304,6 +304,10 @@ Example `.codemap/config.json`:
 {
   "only": ["rs", "sh", "sql", "toml", "yml"],
   "exclude": ["docs/reference", "docs/research"],
+  "guidance": {
+    "missing_extension_hints": true,
+    "ignored_extensions": []
+  },
   "depth": 4,
   "mode": "auto",
   "budgets": {
@@ -331,6 +335,8 @@ Example `.codemap/config.json`:
 }
 ```
 
+When an MCP file search has no visible results but finds real matches hidden by `only`, Codemap reports the matching paths and suggests which extensions to include. These hints still respect `exclude` and never modify project config. Set `guidance.missing_extension_hints` to `false` to disable all hints, or list extensions in `guidance.ignored_extensions` to suppress only those suggestions.
+
 All fields are optional. CLI flags always override config values.
 Hook-specific policy fields are optional and bounded by safe defaults.
 

cmd/context.go

@@ -307,7 +307,7 @@ func detectLanguagesFromFiles(root string) map[string]bool {
 
 	// Include subdirectory source files. Reuse the scan result for countSourceFiles too.
 	gitCache := scanner.NewGitIgnoreCache(root)
-	if files, err := scanner.ScanFiles(root, gitCache, nil, nil); err == nil {
+	if files, err := scanner.ScanConfiguredFiles(root, gitCache); err == nil {
 		for _, f := range files {
 			addLang(scanner.DetectLanguage(f.Path))
 		}
@@ -353,7 +353,7 @@ func countSourceFiles(root string) int {
 		return count
 	}
 	gitCache := scanner.NewGitIgnoreCache(root)
-	files, err := scanner.ScanFiles(root, gitCache, nil, nil)
+	files, err := scanner.ScanConfiguredFiles(root, gitCache)
 	if err != nil {
 		return 0
 	}

cmd/context_test.go

@@ -3,6 +3,7 @@ package cmd
 import (
 	"os"
 	"path/filepath"
+	"reflect"
 	"testing"
 )
 
@@ -41,6 +42,35 @@ func TestDetectLanguagesFromFiles_SubdirectorySources(t *testing.T) {
 	}
 }
 
+func TestBuildContextEnvelopeRespectsConfiguredFilters(t *testing.T) {
+	root := t.TempDir()
+	mustWriteFile(t, filepath.Join(root, ".codemap", "config.json"), `{"only":["go"],"exclude":["generated"]}`)
+	mustWriteFile(t, filepath.Join(root, "main.go"), "package main\n")
+	mustWriteFile(t, filepath.Join(root, "schema.ts"), "export const schema = 1\n")
+	mustWriteFile(t, filepath.Join(root, "generated", "hidden.go"), "package generated\n")
+
+	cachedFileCount = -1
+	t.Cleanup(func() { cachedFileCount = -1 })
+	envelope := buildContextEnvelope(root, "", true)
+
+	if envelope.Project.FileCount != 1 {
+		t.Fatalf("file count = %d, want 1", envelope.Project.FileCount)
+	}
+	if !reflect.DeepEqual(envelope.Project.Languages, []string{"go"}) {
+		t.Fatalf("languages = %#v, want [go]", envelope.Project.Languages)
+	}
+}
+
+func TestCountSourceFilesReturnsZeroWhenConfiguredScanFails(t *testing.T) {
+	cachedFileCount = -1
+	t.Cleanup(func() { cachedFileCount = -1 })
+
+	missingRoot := filepath.Join(t.TempDir(), "missing")
+	if got := countSourceFiles(missingRoot); got != 0 {
+		t.Fatalf("countSourceFiles(missing root) = %d, want 0", got)
+	}
+}
+
 func mustWriteFile(t *testing.T, path, content string) {
 	t.Helper()
 	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {

config/config.go

@@ -13,13 +13,37 @@ import (
 // ProjectConfig holds per-project defaults from .codemap/config.json.
 // All fields are optional; zero values mean "no preference".
 type ProjectConfig struct {
-	Only    []string      `json:"only,omitempty"`
-	Exclude []string      `json:"exclude,omitempty"`
-	Depth   int           `json:"depth,omitempty"`
-	Mode    string        `json:"mode,omitempty"`
-	Budgets HookBudgets   `json:"budgets,omitempty"`
-	Routing RoutingConfig `json:"routing,omitempty"`
-	Drift   DriftConfig   `json:"drift,omitempty"`
+	Only     []string       `json:"only,omitempty"`
+	Exclude  []string       `json:"exclude,omitempty"`
+	Depth    int            `json:"depth,omitempty"`
+	Mode     string         `json:"mode,omitempty"`
+	Budgets  HookBudgets    `json:"budgets,omitempty"`
+	Routing  RoutingConfig  `json:"routing,omitempty"`
+	Drift    DriftConfig    `json:"drift,omitempty"`
+	Guidance GuidanceConfig `json:"guidance,omitempty"`
+}
+
+// GuidanceConfig controls optional suggestions without changing project config.
+type GuidanceConfig struct {
+	MissingExtensionHints *bool    `json:"missing_extension_hints,omitempty"`
+	IgnoredExtensions     []string `json:"ignored_extensions,omitempty"`
+}
+
+// MissingExtensionHintsEnabled defaults missing-extension guidance to on.
+func (c ProjectConfig) MissingExtensionHintsEnabled() bool {
+	return c.Guidance.MissingExtensionHints == nil || *c.Guidance.MissingExtensionHints
+}
+
+// IgnoresGuidanceForExtension reports whether guidance is disabled for ext.
+func (c ProjectConfig) IgnoresGuidanceForExtension(ext string) bool {
+	ext = strings.TrimPrefix(strings.TrimSpace(ext), ".")
+	for _, ignored := range c.Guidance.IgnoredExtensions {
+		ignored = strings.TrimPrefix(strings.TrimSpace(ignored), ".")
+		if strings.EqualFold(ext, ignored) {
+			return true
+		}
+	}
+	return false
 }
 
 // HookBudgets configures per-hook output constraints.
@@ -129,6 +153,9 @@ func (c ProjectConfig) IsZero() bool {
 	if c.Drift.Enabled || c.Drift.RecentCommits > 0 || len(c.Drift.RequireDocsFor) > 0 {
 		return false
 	}
+	if c.Guidance.MissingExtensionHints != nil || len(c.Guidance.IgnoredExtensions) > 0 {
+		return false
+	}
 	return true
 }
 

config/config_test.go

@@ -258,6 +258,38 @@ func TestProjectConfigStateHelpers(t *testing.T) {
 	})
 }
 
+func TestGuidanceConfigHelpers(t *testing.T) {
+	var zero ProjectConfig
+	if !zero.MissingExtensionHintsEnabled() {
+		t.Fatal("expected missing-extension hints to default to enabled")
+	}
+
+	enabled, disabled := true, false
+	if !(ProjectConfig{Guidance: GuidanceConfig{MissingExtensionHints: &enabled}}).MissingExtensionHintsEnabled() {
+		t.Fatal("expected explicitly enabled missing-extension hints")
+	}
+	if (ProjectConfig{Guidance: GuidanceConfig{MissingExtensionHints: &disabled}}).MissingExtensionHintsEnabled() {
+		t.Fatal("expected explicitly disabled missing-extension hints")
+	}
+
+	cfg := ProjectConfig{Guidance: GuidanceConfig{IgnoredExtensions: []string{" .Proto ", "SUM"}}}
+	for _, ext := range []string{".proto", " PROTO", ".sum"} {
+		if !cfg.IgnoresGuidanceForExtension(ext) {
+			t.Fatalf("expected extension %q to be ignored", ext)
+		}
+	}
+	if cfg.IgnoresGuidanceForExtension(".rs") {
+		t.Fatal("did not expect rs guidance to be ignored")
+	}
+
+	if (ProjectConfig{Guidance: GuidanceConfig{MissingExtensionHints: &enabled}}).IsZero() {
+		t.Fatal("config with missing-extension policy must not be zero")
+	}
+	if (ProjectConfig{Guidance: GuidanceConfig{IgnoredExtensions: []string{"proto"}}}).IsZero() {
+		t.Fatal("config with ignored guidance extensions must not be zero")
+	}
+}
+
 func TestAssessSetup(t *testing.T) {
 	t.Run("missing config needs setup", func(t *testing.T) {
 		assessment := AssessSetup(t.TempDir())

mcp/find_guidance.go

@@ -0,0 +1,61 @@
+package codemapmcp
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+
+	"codemap/config"
+	"codemap/scanner"
+)
+
+func findConfiguredMatches(root, pattern string, files []scanner.FileInfo) (visible []string, filtered []scanner.FileInfo, hintsEnabled bool) {
+	cfg := config.Load(root)
+	pattern = strings.ToLower(pattern)
+	for _, file := range files {
+		if !strings.Contains(strings.ToLower(file.Path), pattern) {
+			continue
+		}
+		if scanner.MatchesFilters(file.Path, file.Ext, cfg.Only, cfg.Exclude) {
+			visible = append(visible, file.Path)
+			continue
+		}
+		if !scanner.MatchesFilters(file.Path, file.Ext, cfg.Only, nil) &&
+			scanner.MatchesFilters(file.Path, file.Ext, nil, cfg.Exclude) &&
+			!cfg.IgnoresGuidanceForExtension(file.Ext) {
+			filtered = append(filtered, file)
+		}
+	}
+	return visible, filtered, cfg.MissingExtensionHintsEnabled()
+}
+
+func formatOnlyFilterHint(pattern string, matches []scanner.FileInfo) string {
+	const maxPaths = 5
+	paths := make([]string, 0, min(len(matches), maxPaths))
+	extensions := make(map[string]struct{})
+	for i, match := range matches {
+		if i < maxPaths {
+			paths = append(paths, match.Path)
+		}
+		if ext := strings.TrimPrefix(strings.ToLower(match.Ext), "."); ext != "" {
+			extensions[ext] = struct{}{}
+		}
+	}
+	exts := make([]string, 0, len(extensions))
+	for ext := range extensions {
+		exts = append(exts, ext)
+	}
+	sort.Strings(exts)
+
+	output := fmt.Sprintf("No configured files found matching '%s'.\n\nMatches excluded by `only` config:\n%s", pattern, strings.Join(paths, "\n"))
+	if remaining := len(matches) - len(paths); remaining > 0 {
+		output += fmt.Sprintf("\n... and %d more", remaining)
+	}
+	if len(exts) > 0 {
+		extList := strings.Join(exts, ", ")
+		output += fmt.Sprintf("\n\nTell your agent: “include suggestions for %s”, “ignore suggestions for %s”, or “disable suggestions for this repo”.", extList, extList)
+	} else {
+		output += "\n\nTell your agent: “disable suggestions for this repo”."
+	}
+	return output + "\n\nNo config changed."
+}

mcp/main.go

@@ -221,7 +221,7 @@ func handleGetStructure(ctx context.Context, req *mcp.CallToolRequest, input Pat
 	}
 
 	gitCache := scanner.NewGitIgnoreCache(input.Path)
-	files, err := scanner.ScanFiles(input.Path, gitCache, nil, nil)
+	files, err := scanner.ScanConfiguredFiles(input.Path, gitCache)
 	if err != nil {
 		return errorResult("Scan error: " + err.Error()), nil, nil
 	}
@@ -331,7 +331,7 @@ func handleGetDiff(ctx context.Context, req *mcp.CallToolRequest, input DiffInpu
 	}
 
 	gitCache := scanner.NewGitIgnoreCache(input.Path)
-	files, err := scanner.ScanFiles(input.Path, gitCache, nil, nil)
+	files, err := scanner.ScanConfiguredFiles(input.Path, gitCache)
 	if err != nil {
 		return errorResult("Scan error: " + err.Error()), nil, nil
 	}
@@ -362,15 +362,12 @@ func handleFindFile(ctx context.Context, req *mcp.CallToolRequest, input FindInp
 	}
 
 	// Filter files matching pattern (case-insensitive)
-	var matches []string
-	pattern := strings.ToLower(input.Pattern)
-	for _, f := range files {
-		if strings.Contains(strings.ToLower(f.Path), pattern) {
-			matches = append(matches, f.Path)
-		}
-	}
+	matches, filteredMatches, hintsEnabled := findConfiguredMatches(input.Path, input.Pattern, files)
 
 	if len(matches) == 0 {
+		if hintsEnabled && len(filteredMatches) > 0 {
+			return textResult(formatOnlyFilterHint(input.Pattern, filteredMatches)), nil, nil
+		}
 		return textResult("No files found matching '" + input.Pattern + "'"), nil, nil
 	}
 
@@ -483,7 +480,7 @@ func handleListProjects(ctx context.Context, req *mcp.CallToolRequest, input Lis
 // Uses the same scanner logic as the main codemap command (respects nested .gitignore files)
 func getProjectStats(path string) string {
 	gitCache := scanner.NewGitIgnoreCache(path)
-	files, err := scanner.ScanFiles(path, gitCache, nil, nil)
+	files, err := scanner.ScanConfiguredFiles(path, gitCache)
 	if err != nil {
 		return "(error scanning)"
 	}

mcp/main_more_test.go

@@ -109,6 +109,95 @@ func TestHandleGetDependenciesAndDiff(t *testing.T) {
 	}
 }
 
+func TestMCPScansRespectConfiguredFilters(t *testing.T) {
+	if _, err := exec.LookPath("git"); err != nil {
+		t.Skip("git not available")
+	}
+	if !scanner.NewAstGrepAnalyzer().Available() {
+		t.Skip("ast-grep not available")
+	}
+
+	root := makeMCPGitRepo(t, "main")
+	files := map[string]string{
+		".codemap/config.json": `{"only":["go"],"exclude":["excluded"]}`,
+		"go.mod":               "module example.com/mcpfiltered\n\ngo 1.22\n",
+		"pkg/types/types.go":   "package types\n\ntype Item struct{}\n",
+		"a/a.go":               "package a\n\nimport _ \"example.com/mcpfiltered/pkg/types\"\n",
+		"b/b.go":               "package b\n\nimport _ \"example.com/mcpfiltered/pkg/types\"\n",
+		"c/c.go":               "package c\n\nimport _ \"example.com/mcpfiltered/pkg/types\"\n",
+		"schema.ts":            "export const schema = 1\n",
+		"excluded/d/d.go":      "package d\n\nimport _ \"example.com/mcpfiltered/pkg/types\"\n",
+	}
+	for path, content := range files {
+		full := filepath.Join(root, path)
+		if err := os.MkdirAll(filepath.Dir(full), 0o755); err != nil {
+			t.Fatal(err)
+		}
+		if err := os.WriteFile(full, []byte(content), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+	runGitMCPTestCmd(t, root, "add", ".")
+	runGitMCPTestCmd(t, root, "-c", "user.name=Test", "-c", "user.email=test@example.com", "commit", "-m", "fixture")
+
+	for path, content := range map[string]string{
+		"a/a.go":          "package a\n\nimport _ \"example.com/mcpfiltered/pkg/types\"\n\nfunc Changed() {}\n",
+		"schema.ts":       "export const schema = 2\n",
+		"excluded/d/d.go": "package d\n\nimport _ \"example.com/mcpfiltered/pkg/types\"\n\nfunc Changed() {}\n",
+	} {
+		if err := os.WriteFile(filepath.Join(root, path), []byte(content), 0o644); err != nil {
+			t.Fatal(err)
+		}
+	}
+
+	structure, _, err := handleGetStructure(context.Background(), nil, PathInput{Path: root})
+	if err != nil {
+		t.Fatalf("handleGetStructure error: %v", err)
+	}
+	structureOut := resultText(t, structure)
+	for _, want := range []string{"main.go", "types.go", "a.go"} {
+		if !strings.Contains(structureOut, want) {
+			t.Fatalf("structure missing %q:\n%s", want, structureOut)
+		}
+	}
+	for _, unwanted := range []string{"schema.ts", "excluded"} {
+		if strings.Contains(structureOut, unwanted) {
+			t.Fatalf("structure contains configured-out %q:\n%s", unwanted, structureOut)
+		}
+	}
+
+	diff, _, err := handleGetDiff(context.Background(), nil, DiffInput{Path: root, Ref: "main"})
+	if err != nil {
+		t.Fatalf("handleGetDiff error: %v", err)
+	}
+	diffOut := resultText(t, diff)
+	if !strings.Contains(diffOut, "a.go") || strings.Contains(diffOut, "schema.ts") || strings.Contains(diffOut, "excluded") {
+		t.Fatalf("unexpected filtered diff:\n%s", diffOut)
+	}
+
+	deps, _, err := handleGetDependencies(context.Background(), nil, PathInput{Path: root})
+	if err != nil {
+		t.Fatalf("handleGetDependencies error: %v", err)
+	}
+	depsOut := resultText(t, deps)
+	if strings.Contains(depsOut, "schema.ts") || strings.Contains(depsOut, "excluded/d/d.go") {
+		t.Fatalf("dependencies contain configured-out files:\n%s", depsOut)
+	}
+
+	hubs, _, err := handleGetHubs(context.Background(), nil, PathInput{Path: root})
+	if err != nil {
+		t.Fatalf("handleGetHubs error: %v", err)
+	}
+	hubsOut := resultText(t, hubs)
+	if !strings.Contains(hubsOut, "pkg/types/types.go (3 importers)") || strings.Contains(hubsOut, "excluded/d/d.go") {
+		t.Fatalf("unexpected filtered hubs:\n%s", hubsOut)
+	}
+
+	if got := getProjectStats(root); !strings.Contains(got, "(5 files, Go") {
+		t.Fatalf("project stats = %q, want 5 filtered Go files", got)
+	}
+}
+
 func TestHandleWatchLifecycleAndActivity(t *testing.T) {
 	withWatcherRegistry(t)