fix(engram): prevent double MCP registration in Antigravity and support Linuxbrew path

internal/components/engram/inject.go

@@ -130,11 +130,6 @@ func engramOverlayJSON(agentID model.AgentID, cmd string) []byte {
 		}
 	} else {
 		args := []string{"mcp", "--tools=agent"}
-		if agentID == model.AgentAntigravity {
-			// Antigravity should launch the default Engram MCP server without
-			// narrowing the exposed tool set.
-			args = []string{"mcp"}
-		}
 		cfg = map[string]any{
 			"mcpServers": map[string]any{
 				"engram": map[string]any{
@@ -275,14 +270,6 @@ func installAntigravityEngramPlugin(homeDir, engramCommand string) (bool, []stri
 	changed = changed || pluginWrite.Changed
 	files = append(files, pluginPath)
 
-	pluginMCPPath := filepath.Join(pluginDir, "mcp_config.json")
-	mcpWrite, err := filemerge.WriteFileAtomic(pluginMCPPath, engramOverlayJSON(model.AgentAntigravity, engramCommand), 0o644)
-	if err != nil {
-		return false, nil, fmt.Errorf("write Antigravity Engram plugin MCP config: %w", err)
-	}
-	changed = changed || mcpWrite.Changed
-	files = append(files, pluginMCPPath)
-
 	hooksPath := filepath.Join(pluginDir, "hooks.json")
 	hooksWrite, err := filemerge.WriteFileAtomic(hooksPath, antigravityEngramHooksJSON(), 0o644)
 	if err != nil {
@@ -854,7 +841,7 @@ func isVersionedHomebrewCellarPath(path string) bool {
 
 func isStableHomebrewEngramPath(path string) bool {
 	clean := filepath.ToSlash(filepath.Clean(path))
-	return (clean == "/opt/homebrew/bin/engram" || clean == "/usr/local/bin/engram") && isEngramCommand(clean)
+	return (clean == "/opt/homebrew/bin/engram" || clean == "/usr/local/bin/engram" || clean == "/home/linuxbrew/.linuxbrew/bin/engram") && isEngramCommand(clean)
 }
 
 // resolveProfileAssignments builds the []codex.ProfileAssignment slice used

internal/components/engram/inject_test.go

@@ -582,8 +582,8 @@ func TestInjectAntigravityWritesMCPToCLIConfig(t *testing.T) {
 	if !strings.Contains(text, `"args": [`) || !strings.Contains(text, `"mcp"`) {
 		t.Fatalf("Antigravity MCP config must launch Engram MCP; got:\n%s", text)
 	}
-	if strings.Contains(text, `--tools=`) {
-		t.Fatalf("Antigravity should use Engram's default MCP invocation without tool-profile flags; got:\n%s", text)
+	if !strings.Contains(text, `"--tools=agent"`) {
+		t.Fatalf("Antigravity should use Engram's agent MCP invocation with tool-profile flags; got:\n%s", text)
 	}
 
 	pluginPath := filepath.Join(home, ".gemini", "antigravity-cli", "plugins", "gentle-ai-engram", "plugin.json")
@@ -592,13 +592,8 @@ func TestInjectAntigravityWritesMCPToCLIConfig(t *testing.T) {
 	}
 
 	pluginMCPPath := filepath.Join(home, ".gemini", "antigravity-cli", "plugins", "gentle-ai-engram", "mcp_config.json")
-	pluginMCPContent, err := os.ReadFile(pluginMCPPath)
-	if err != nil {
-		t.Fatalf("ReadFile(%q) error = %v", pluginMCPPath, err)
-	}
-	pluginMCPText := string(pluginMCPContent)
-	if !strings.Contains(pluginMCPText, `"mcp"`) || strings.Contains(pluginMCPText, `--tools=`) {
-		t.Fatalf("Antigravity Engram plugin MCP config should expose default Engram MCP tools; got:\n%s", pluginMCPText)
+	if _, err := os.Stat(pluginMCPPath); !os.IsNotExist(err) {
+		t.Fatalf("Antigravity Engram plugin MCP config should NOT be written: %v", err)
 	}
 
 	hooksPath := filepath.Join(home, ".gemini", "antigravity-cli", "plugins", "gentle-ai-engram", "hooks.json")

testdata/golden/engram-antigravity-mcp.golden

@@ -2,7 +2,8 @@
   "mcpServers": {
     "engram": {
       "args": [
-        "mcp"
+        "mcp",
+        "--tools=agent"
       ],
       "command": "/opt/homebrew/bin/engram"
     }