Enhance language detection: more manifest signals, recursive scan, Makefile heuristics, and tests (#57)

* Improve detectLanguagesFromFiles fallback coverage

* fix: address review comments on language detection

- Remove 'make' sentinel from manifests, check Makefile directly
- Tighten C heuristic: exclude clang++ false positive
- Cache ScanFiles result to avoid double directory walk
- Fix build error in countSourceFiles

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

---------

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

Author: JordanCoin

cmd/context.go

@@ -4,9 +4,11 @@ import (
 	"encoding/json"
 	"flag"
 	"fmt"
+	"io"
 	"os"
 	"path/filepath"
 	"sort"
+	"strings"
 	"time"
 
 	"codemap/config"
@@ -248,63 +250,112 @@ func buildProjectContext(root string, info *hubInfo) ProjectContext {
 	return ctx
 }
 
-// detectLanguagesFromFiles does a quick scan of the project root for language signals.
-// Checks manifest files first (fast), then scans top-level source files.
+// detectLanguagesFromFiles does a quick scan for language signals.
+// Checks manifest files first (fast), then scans source files recursively.
 func detectLanguagesFromFiles(root string) map[string]bool {
 	langs := make(map[string]bool)
+	addLang := func(lang string) {
+		if lang != "" {
+			langs[lang] = true
+		}
+	}
 
 	// Manifest files → definitive language signal
-	manifests := map[string]string{
-		"go.mod":           "go",
-		"package.json":     "javascript",
-		"Cargo.toml":       "rust",
-		"pyproject.toml":   "python",
-		"setup.py":         "python",
-		"requirements.txt": "python",
-		"Gemfile":          "ruby",
-		"build.gradle":     "java",
-		"pom.xml":          "java",
-		"Package.swift":    "swift",
-		"mix.exs":          "elixir",
-		"composer.json":    "php",
-		"build.sbt":        "scala",
+	manifests := map[string][]string{
+		"go.mod":           {"go"},
+		"package.json":     {"javascript"},
+		"Cargo.toml":       {"rust"},
+		"pyproject.toml":   {"python"},
+		"setup.py":         {"python"},
+		"requirements.txt": {"python"},
+		"Gemfile":          {"ruby"},
+		"build.gradle":     {"java"},
+		"build.gradle.kts": {"kotlin", "java"},
+		"pom.xml":          {"java"},
+		"Package.swift":    {"swift"},
+		"Podfile":          {"swift"},
+		"mix.exs":          {"elixir"},
+		"composer.json":    {"php"},
+		"build.sbt":        {"scala"},
+		"tsconfig.json":    {"typescript"},
 	}
-	for file, lang := range manifests {
+	for file, signalLangs := range manifests {
 		if _, err := os.Stat(filepath.Join(root, file)); err == nil {
-			langs[lang] = true
+			for _, lang := range signalLangs {
+				addLang(lang)
+			}
 		}
 	}
 
-	// If we found manifests, that's usually enough
-	if len(langs) > 0 {
-		return langs
+	// C# project files can have arbitrary names; detect by glob at repo root.
+	for _, pattern := range []string{"*.csproj", "*.sln"} {
+		matches, _ := filepath.Glob(filepath.Join(root, pattern))
+		if len(matches) > 0 {
+			addLang("csharp")
+		}
 	}
 
-	// Fall back to scanning top-level files by extension
-	entries, err := os.ReadDir(root)
-	if err != nil {
-		return langs
+	// JS/TS monorepo signal: packages/*/package.json.
+	if matches, _ := filepath.Glob(filepath.Join(root, "packages", "*", "package.json")); len(matches) > 0 {
+		addLang("javascript")
 	}
-	for _, entry := range entries {
-		if entry.IsDir() {
-			continue
-		}
-		if lang := scanner.DetectLanguage(entry.Name()); lang != "" {
-			langs[lang] = true
+
+	// Makefile heuristics for C/C++ projects — check directly, no sentinel.
+	if _, err := os.Stat(filepath.Join(root, "Makefile")); err == nil {
+		applyMakefileHeuristics(filepath.Join(root, "Makefile"), addLang)
+	}
+
+	// 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 {
+		for _, f := range files {
+			addLang(scanner.DetectLanguage(f.Path))
 		}
+		// Cache file count to avoid a second scan in countSourceFiles
+		cachedFileCount = len(files)
 	}
 
 	return langs
 }
 
+// cachedFileCount avoids a second ScanFiles walk in countSourceFiles.
+var cachedFileCount = -1
+
+func applyMakefileHeuristics(path string, addLang func(string)) {
+	f, err := os.Open(path)
+	if err != nil {
+		return
+	}
+	defer f.Close()
+
+	buf, err := io.ReadAll(io.LimitReader(f, 128*1024))
+	if err != nil {
+		return
+	}
+	content := strings.ToLower(string(buf))
+
+	if strings.Contains(content, "g++") || strings.Contains(content, "clang++") || strings.Contains(content, ".cpp") || strings.Contains(content, ".cc") {
+		addLang("cpp")
+	}
+	// Tighten C detection: exclude clang++ and .cpp/.cc false positives
+	if strings.Contains(content, "gcc") ||
+		(strings.Contains(content, "clang") && !strings.Contains(content, "clang++")) {
+		addLang("c")
+	}
+}
+
 // countSourceFiles does a quick count of source files in the project.
+// Uses cached result from detectLanguagesFromFiles if available.
 func countSourceFiles(root string) int {
-	count := 0
+	if cachedFileCount >= 0 {
+		count := cachedFileCount
+		cachedFileCount = -1 // reset for next call
+		return count
+	}
 	gitCache := scanner.NewGitIgnoreCache(root)
 	files, err := scanner.ScanFiles(root, gitCache, nil, nil)
 	if err != nil {
 		return 0
 	}
-	count = len(files)
-	return count
+	return len(files)
 }

cmd/context_test.go

@@ -0,0 +1,52 @@
+package cmd
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+func TestDetectLanguagesFromFiles_ManifestSignals(t *testing.T) {
+	root := t.TempDir()
+
+	mustWriteFile(t, filepath.Join(root, "app.csproj"), "<Project />")
+	mustWriteFile(t, filepath.Join(root, "build.gradle.kts"), "plugins { kotlin(\"jvm\") }")
+	mustWriteFile(t, filepath.Join(root, "Podfile"), "platform :ios, '13.0'")
+	mustWriteFile(t, filepath.Join(root, "tsconfig.json"), "{}")
+	mustWriteFile(t, filepath.Join(root, "Makefile"), "CC=gcc\nCXX=g++\n")
+	mustWriteFile(t, filepath.Join(root, "packages", "ui", "package.json"), "{}")
+
+	langs := detectLanguagesFromFiles(root)
+
+	for _, want := range []string{"csharp", "kotlin", "java", "swift", "typescript", "javascript", "c", "cpp"} {
+		if !langs[want] {
+			t.Fatalf("expected %q to be detected, got %#v", want, langs)
+		}
+	}
+}
+
+func TestDetectLanguagesFromFiles_SubdirectorySources(t *testing.T) {
+	root := t.TempDir()
+
+	mustWriteFile(t, filepath.Join(root, "src", "main.ts"), "export const n = 1")
+	mustWriteFile(t, filepath.Join(root, "internal", "core", "worker.go"), "package core")
+
+	langs := detectLanguagesFromFiles(root)
+
+	if !langs["typescript"] {
+		t.Fatalf("expected typescript from subdirectory source, got %#v", langs)
+	}
+	if !langs["go"] {
+		t.Fatalf("expected go from subdirectory source, got %#v", langs)
+	}
+}
+
+func mustWriteFile(t *testing.T, path, content string) {
+	t.Helper()
+	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
+		t.Fatalf("mkdir %s: %v", path, err)
+	}
+	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
+		t.Fatalf("write %s: %v", path, err)
+	}
+}