diff --git a/README.md b/README.md
index 99190d7..4ee1df6 100644
--- a/README.md
+++ b/README.md
@@ -45,6 +45,30 @@ devtap install --adapter claude-code
 
 This configures the MCP server and injects devtap instructions into your project's instruction file (e.g., `CLAUDE.md`). See [Supported Tools](#supported-tools) for all available adapters.
 
+### Skills (Optional)
+
+devtap ships with a built-in [skill](https://docs.anthropic.com/en/docs/claude-code/skills) that works as a CLI fallback when MCP is unavailable. Install it to let the agent fetch build output on demand:
+
+```bash
+# Claude Code
+mkdir -p ~/.claude/skills && cp -r skills/devtap-get-build-errors ~/.claude/skills/
+
+# Codex CLI
+mkdir -p ~/.codex/skills && cp -r skills/devtap-get-build-errors ~/.codex/skills/
+```
+
+Or fetch directly from the repo without cloning:
+
+```bash
+DEST=~/.claude/skills/devtap-get-build-errors
+mkdir -p "$DEST" && cd "$DEST"
+for f in SKILL.md scripts/get_build_errors.sh; do
+  mkdir -p "$(dirname "$f")"
+  curl -sL "https://raw.githubusercontent.com/killme2008/devtap/main/skills/devtap-get-build-errors/$f" -o "$f"
+done
+chmod +x scripts/get_build_errors.sh
+```
+
 ### Usage
 
 **Terminal A** — capture build output:
@@ -299,7 +323,9 @@ Subcommands:
   install     Configure AI tool integration (--session and --store are forwarded to MCP config)
   mcp-serve   Start MCP stdio server
   drain       Read pending messages as plain text
+                -q, --quiet      Raw output without source/tag headers
   status      Show pending message counts
+                -q, --quiet      Compact output (pending count only)
   history     Query build error history (GreptimeDB only)
                 --since <dur>    Time range (default "24h")
                 --tag <label>    Filter by tag
diff --git a/cmd/devtap/drain.go b/cmd/devtap/drain.go
index 6a703b9..a5c8bbd 100644
--- a/cmd/devtap/drain.go
+++ b/cmd/devtap/drain.go
@@ -29,6 +29,7 @@ For MCP-capable tools, use "devtap mcp-serve" instead.`,
 	cmd.Flags().Int("max-retries", 5, "max retries for auto-loop")
 	cmd.Flags().Int("max-lines", 10000, "max lines to drain")
 	cmd.Flags().String("filter-sql", "", "SQL WHERE clause for GreptimeDB filtering")
+	cmd.Flags().BoolP("quiet", "q", false, "raw output without source headers")
 
 	return cmd
 }
@@ -39,6 +40,7 @@ func runDrain(cmd *cobra.Command, args []string) error {
 	maxRetries, _ := cmd.Flags().GetInt("max-retries")
 	maxLines, _ := cmd.Flags().GetInt("max-lines")
 	filterSQL, _ := cmd.Flags().GetString("filter-sql")
+	quiet, _ := cmd.Flags().GetBool("quiet")
 
 	if maxLines <= 0 {
 		maxLines = 10000
@@ -46,7 +48,7 @@ func runDrain(cmd *cobra.Command, args []string) error {
 
 	// If --filter-sql is set, fall back to single-source drain against the configured store.
 	if filterSQL != "" {
-		return runDrainSingleSource(cmd, filterSQL, maxLines, event, autoLoop, maxRetries)
+		return runDrainSingleSource(cmd, filterSQL, maxLines, event, autoLoop, maxRetries, quiet)
 	}
 
 	sources, cleanup, err := resolveDrainSources(cmd)
@@ -136,6 +138,10 @@ func runDrain(cmd *cobra.Command, args []string) error {
 	}
 
 	// Plain text output
+	if quiet {
+		fmt.Println(mcp.FormatMessagesRaw(allMessages))
+		return nil
+	}
 	if multiSource {
 		var sourceLabels []string
 		for _, src := range sources {
@@ -148,7 +154,7 @@ func runDrain(cmd *cobra.Command, args []string) error {
 }
 
 // runDrainSingleSource handles drain with --filter-sql which only works with a single GreptimeDB store.
-func runDrainSingleSource(cmd *cobra.Command, filterSQL string, maxLines int, event string, autoLoop bool, maxRetries int) error {
+func runDrainSingleSource(cmd *cobra.Command, filterSQL string, maxLines int, event string, autoLoop bool, maxRetries int, quiet bool) error {
 	adapterName, _ := cmd.Flags().GetString("adapter")
 	sessionFlag, _ := cmd.Flags().GetString("session")
 
@@ -194,7 +200,11 @@ func runDrainSingleSource(cmd *cobra.Command, filterSQL string, maxLines int, ev
 		return nil
 	}
 
-	fmt.Println(mcp.FormatMessages(messages))
+	if quiet {
+		fmt.Println(mcp.FormatMessagesRaw(messages))
+	} else {
+		fmt.Println(mcp.FormatMessages(messages))
+	}
 	return nil
 }
 
diff --git a/cmd/devtap/status.go b/cmd/devtap/status.go
index 2ff5275..c4e3ee8 100644
--- a/cmd/devtap/status.go
+++ b/cmd/devtap/status.go
@@ -5,16 +5,19 @@ import (
 
 	"github.com/spf13/cobra"
 
+	"github.com/killme2008/devtap/internal/store"
 	greptimestore "github.com/killme2008/devtap/internal/store/greptimedb"
 )
 
 func statusCmd() *cobra.Command {
-	return &cobra.Command{
+	cmd := &cobra.Command{
 		Use:          "status",
 		Short:        "Show pending message counts per session",
 		SilenceUsage: true,
 		RunE:         runStatus,
 	}
+	cmd.Flags().BoolP("quiet", "q", false, "compact output (pending count only)")
+	return cmd
 }
 
 func runStatus(cmd *cobra.Command, args []string) error {
@@ -28,6 +31,11 @@ func runStatus(cmd *cobra.Command, args []string) error {
 	if adapter == "" {
 		adapter = "claude-code"
 	}
+	quiet, _ := cmd.Flags().GetBool("quiet")
+
+	if quiet {
+		return runStatusQuiet(s)
+	}
 
 	// Try extended status for GreptimeDB
 	if gs, ok := s.(*greptimestore.Store); ok {
@@ -52,6 +60,19 @@ func runStatus(cmd *cobra.Command, args []string) error {
 	return nil
 }
 
+func runStatusQuiet(s store.Store) error {
+	counts, err := s.Status()
+	if err != nil {
+		return fmt.Errorf("get status: %w", err)
+	}
+	total := 0
+	for _, count := range counts {
+		total += count
+	}
+	fmt.Println(total)
+	return nil
+}
+
 func showExtendedStatus(gs *greptimestore.Store, adapter string) error {
 	// Show pending counts first
 	counts, err := gs.Status()
diff --git a/cmd/devtap/storefactory_test.go b/cmd/devtap/storefactory_test.go
new file mode 100644
index 0000000..c0460ea
--- /dev/null
+++ b/cmd/devtap/storefactory_test.go
@@ -0,0 +1,52 @@
+package main
+
+import (
+	"testing"
+
+	"github.com/killme2008/devtap/internal/config"
+)
+
+func TestOpenStoreStrictFileBackend(t *testing.T) {
+	dir := t.TempDir()
+	cfg := config.Default()
+
+	s, err := openStoreStrict(cfg, "file", dir, "claude-code")
+	if err != nil {
+		t.Fatalf("openStoreStrict(file): %v", err)
+	}
+	_ = s.Close()
+}
+
+func TestOpenStoreStrictEmptyBackend(t *testing.T) {
+	dir := t.TempDir()
+	cfg := config.Default()
+
+	s, err := openStoreStrict(cfg, "", dir, "claude-code")
+	if err != nil {
+		t.Fatalf("openStoreStrict(''): %v", err)
+	}
+	_ = s.Close()
+}
+
+func TestOpenStoreStrictUnknownBackend(t *testing.T) {
+	dir := t.TempDir()
+	cfg := config.Default()
+
+	_, err := openStoreStrict(cfg, "redis", dir, "claude-code")
+	if err == nil {
+		t.Fatal("expected error for unknown backend")
+	}
+}
+
+func TestOpenStoreStrictGreptimeDBNoFallback(t *testing.T) {
+	dir := t.TempDir()
+	cfg := config.Default()
+	// Point to an unreachable endpoint so New or Ping fails.
+	cfg.Store.GreptimeDB.Endpoint = "127.0.0.1:19999"
+	cfg.Store.GreptimeDB.MySQLEndpoint = "127.0.0.1:19998"
+
+	_, err := openStoreStrict(cfg, "greptimedb", dir, "claude-code")
+	if err == nil {
+		t.Fatal("expected error when greptimedb is unreachable, should not fall back to file store")
+	}
+}
diff --git a/internal/mcp/server.go b/internal/mcp/server.go
index 95ac015..39f26ef 100644
--- a/internal/mcp/server.go
+++ b/internal/mcp/server.go
@@ -362,6 +362,27 @@ func (s *Server) writeJSON(v any) {
 	_, _ = fmt.Fprintf(s.output, "%s\n", data)
 }
 
+// FormatMessagesRaw outputs raw lines without [devtap: tag] headers.
+// Messages are separated by blank lines.
+func FormatMessagesRaw(messages []store.LogMessage) string {
+	var sb strings.Builder
+	wroteAny := false
+	for _, msg := range messages {
+		if len(msg.Lines) == 0 {
+			continue
+		}
+		if wroteAny {
+			sb.WriteString("\n")
+		}
+		for _, line := range msg.Lines {
+			sb.WriteString(line)
+			sb.WriteString("\n")
+		}
+		wroteAny = true
+	}
+	return strings.TrimRight(sb.String(), "\n")
+}
+
 // FormatMessages converts log messages into a human-readable string.
 func FormatMessages(messages []store.LogMessage) string {
 	var sb strings.Builder
diff --git a/internal/mcp/server_test.go b/internal/mcp/server_test.go
index b661f7e..6fb23ec 100644
--- a/internal/mcp/server_test.go
+++ b/internal/mcp/server_test.go
@@ -474,6 +474,50 @@ func TestFormatMessagesNoExitCode(t *testing.T) {
 	}
 }
 
+func TestFormatMessagesRaw(t *testing.T) {
+	exitCode := 1
+	messages := []store.LogMessage{
+		{Tag: "mypy", Stream: "stderr", Lines: []string{"main.py:5: error: Incompatible types"}, ExitCode: &exitCode},
+		{Tag: "go-build", Stream: "stdout", Lines: []string{"ok", "all good"}},
+	}
+
+	text := FormatMessagesRaw(messages)
+
+	// Should contain raw lines without [devtap: tag] headers
+	if strings.Contains(text, "[devtap:") {
+		t.Error("raw output should not contain [devtap:] headers")
+	}
+	if !strings.Contains(text, "Incompatible types") {
+		t.Error("should contain error line")
+	}
+	if !strings.Contains(text, "all good") {
+		t.Error("should contain all lines")
+	}
+	// Messages separated by blank line
+	if !strings.Contains(text, "Incompatible types\n\nok") {
+		t.Errorf("messages should be separated by blank line, got:\n%s", text)
+	}
+}
+
+func TestFormatMessagesRawEmpty(t *testing.T) {
+	text := FormatMessagesRaw(nil)
+	if text != "" {
+		t.Errorf("empty input should produce empty output, got: %q", text)
+	}
+}
+
+func TestFormatMessagesRawSkipsEmptyLines(t *testing.T) {
+	messages := []store.LogMessage{
+		{Tag: "a", Lines: []string{}},
+		{Tag: "b", Lines: []string{"hello"}},
+	}
+
+	text := FormatMessagesRaw(messages)
+	if text != "hello" {
+		t.Errorf("expected %q, got %q", "hello", text)
+	}
+}
+
 // --- Multi-source tests ---
 
 // errStore implements store.Store and returns configurable errors on Drain/Status.
diff --git a/skills/devtap-get-build-errors/SKILL.md b/skills/devtap-get-build-errors/SKILL.md
new file mode 100644
index 0000000..741b249
--- /dev/null
+++ b/skills/devtap-get-build-errors/SKILL.md
@@ -0,0 +1,28 @@
+---
+name: devtap-get-build-errors
+description: Fetch pending devtap build/dev output for the current turn using get_build_status and get_build_errors, then present the captured output verbatim. Use when the user asks to check build errors, latest build logs, or "/get_build_errors"-style actions.
+metadata:
+  short-description: Fetch devtap output
+---
+
+# devtap-get-build-errors
+
+Use this skill when the user asks for build errors, latest build output, or an equivalent quick action.
+
+## Workflow
+
+1. Call `get_build_status` once.
+2. Call `get_build_errors` once when any of these is true:
+   - status reports pending output
+   - user explicitly asks to fetch/check logs now
+   - user says new build/test/dev output arrived
+3. Present `get_build_errors` content verbatim in a fenced code block.
+4. Keep source warnings verbatim (for example, unreachable source warnings).
+5. After the block, add one line: `Next action: <what you will do>`.
+
+## Rules
+
+- Do not summarize or rewrite build output.
+- Do not call `get_build_errors` repeatedly in the same turn unless new output is reported.
+- MCP tool names map to CLI subcommands: `get_build_status` → `devtap status`, `get_build_errors` → `devtap drain`.
+- If MCP tools are unavailable, use `scripts/get_build_errors.sh` as CLI fallback.
diff --git a/skills/devtap-get-build-errors/scripts/get_build_errors.sh b/skills/devtap-get-build-errors/scripts/get_build_errors.sh
new file mode 100755
index 0000000..55c280b
--- /dev/null
+++ b/skills/devtap-get-build-errors/scripts/get_build_errors.sh
@@ -0,0 +1,14 @@
+#!/usr/bin/env sh
+set -eu
+
+MAX_LINES="${1:-10000}"
+
+if ! command -v devtap >/dev/null 2>&1; then
+  echo "devtap not found in PATH" >&2
+  exit 127
+fi
+
+pending_count=$(devtap status --quiet 2>/dev/null || echo 0)
+if [ "$pending_count" -gt 0 ] 2>/dev/null; then
+  devtap drain --max-lines "$MAX_LINES"
+fi