fix: Gemini engine uses .gemini/settings.json instead of unsupported --mcp-config flag

actions/setup/sh/convert_gateway_config_gemini.sh

@@ -0,0 +1,103 @@
+#!/usr/bin/env bash
+# Convert MCP Gateway Configuration to Gemini Format
+# This script converts the gateway's standard HTTP-based MCP configuration
+# to the JSON format expected by Gemini CLI (.gemini/settings.json)
+#
+# Gemini CLI reads MCP server configuration from settings.json files:
+# - Global: ~/.gemini/settings.json
+# - Project: .gemini/settings.json (used here)
+#
+# See: https://geminicli.com/docs/tools/mcp-server/
+
+set -e
+
+# Required environment variables:
+# - MCP_GATEWAY_OUTPUT: Path to gateway output configuration file
+# - MCP_GATEWAY_DOMAIN: Domain to use for MCP server URLs (e.g., host.docker.internal)
+# - MCP_GATEWAY_PORT: Port for MCP gateway (e.g., 80)
+# - GITHUB_WORKSPACE: Workspace directory for project-level settings
+
+if [ -z "$MCP_GATEWAY_OUTPUT" ]; then
+  echo "ERROR: MCP_GATEWAY_OUTPUT environment variable is required"
+  exit 1
+fi
+
+if [ ! -f "$MCP_GATEWAY_OUTPUT" ]; then
+  echo "ERROR: Gateway output file not found: $MCP_GATEWAY_OUTPUT"
+  exit 1
+fi
+
+if [ -z "$MCP_GATEWAY_DOMAIN" ]; then
+  echo "ERROR: MCP_GATEWAY_DOMAIN environment variable is required"
+  exit 1
+fi
+
+if [ -z "$MCP_GATEWAY_PORT" ]; then
+  echo "ERROR: MCP_GATEWAY_PORT environment variable is required"
+  exit 1
+fi
+
+if [ -z "$GITHUB_WORKSPACE" ]; then
+  echo "ERROR: GITHUB_WORKSPACE environment variable is required"
+  exit 1
+fi
+
+echo "Converting gateway configuration to Gemini format..."
+echo "Input: $MCP_GATEWAY_OUTPUT"
+echo "Target domain: $MCP_GATEWAY_DOMAIN:$MCP_GATEWAY_PORT"
+
+# Convert gateway output to Gemini settings.json format
+# Gateway format:
+# {
+#   "mcpServers": {
+#     "server-name": {
+#       "type": "http",
+#       "url": "http://domain:port/mcp/server-name",
+#       "headers": {
+#         "Authorization": "apiKey"
+#       }
+#     }
+#   }
+# }
+#
+# Gemini settings.json format:
+# {
+#   "mcpServers": {
+#     "server-name": {
+#       "url": "http://domain:port/mcp/server-name",
+#       "headers": {
+#         "Authorization": "apiKey"
+#       }
+#     }
+#   }
+# }
+#
+# The main differences:
+# 1. Remove "type" field (Gemini uses transport auto-detection from url/httpUrl)
+# 2. Remove "tools" field (Copilot-specific)
+# 3. URLs must use the correct domain (host.docker.internal) for container access
+
+# Build the correct URL prefix using the configured domain and port
+URL_PREFIX="http://${MCP_GATEWAY_DOMAIN}:${MCP_GATEWAY_PORT}"
+
+# Create .gemini directory in the workspace (project-level settings)
+GEMINI_SETTINGS_DIR="${GITHUB_WORKSPACE}/.gemini"
+GEMINI_SETTINGS_FILE="${GEMINI_SETTINGS_DIR}/settings.json"
+
+mkdir -p "$GEMINI_SETTINGS_DIR"
+
+jq --arg urlPrefix "$URL_PREFIX" '
+  .mcpServers |= with_entries(
+    .value |= (
+      (del(.type)) |
+      (del(.tools)) |
+      # Fix the URL to use the correct domain
+      .url |= (. | sub("^http://[^/]+/mcp/"; $urlPrefix + "/mcp/"))
+    )
+  )
+' "$MCP_GATEWAY_OUTPUT" > "$GEMINI_SETTINGS_FILE"
+
+echo "Gemini configuration written to $GEMINI_SETTINGS_FILE"
+echo ""
+echo "Converted configuration:"
+cat "$GEMINI_SETTINGS_FILE"

actions/setup/sh/start_mcp_gateway.sh

@@ -365,6 +365,10 @@ case "$ENGINE_TYPE" in
     echo "Using Claude converter..."
     bash /opt/gh-aw/actions/convert_gateway_config_claude.sh
     ;;
+  gemini)
+    echo "Using Gemini converter..."
+    bash /opt/gh-aw/actions/convert_gateway_config_gemini.sh
+    ;;
   *)
     echo "No agent-specific converter found for engine: $ENGINE_TYPE"
     echo "Using gateway output directly"

pkg/workflow/gemini_engine.go

@@ -172,10 +172,9 @@ func (e *GeminiEngine) GetExecutionSteps(workflowData *WorkflowData, logFile str
 		geminiArgs = append(geminiArgs, "--model", workflowData.EngineConfig.Model)
 	}
 
-	// Add MCP config if servers are present
-	if HasMCPServers(workflowData) {
-		geminiArgs = append(geminiArgs, "--mcp-config", "/tmp/gh-aw/mcp-config/mcp-servers.json")
-	}
+	// Gemini CLI reads MCP config from .gemini/settings.json (project-level)
+	// The conversion script (convert_gateway_config_gemini.sh) writes settings.json
+	// during the MCP setup step, so no --mcp-config flag is needed here.
 
 	// Add headless mode with JSON output
 	geminiArgs = append(geminiArgs, "--output-format", "json")
@@ -225,9 +224,9 @@ func (e *GeminiEngine) GetExecutionSteps(workflowData *WorkflowData, logFile str
 		"GITHUB_WORKSPACE": "${{ github.workspace }}",
 	}
 
-	// Add MCP config env var if needed
+	// Add MCP config env var if needed (points to .gemini/settings.json for Gemini)
 	if HasMCPServers(workflowData) {
-		env["GH_AW_MCP_CONFIG"] = "/tmp/gh-aw/mcp-config/mcp-servers.json"
+		env["GH_AW_MCP_CONFIG"] = "${{ github.workspace }}/.gemini/settings.json"
 	}
 
 	// Add safe outputs env

pkg/workflow/gemini_engine_test.go

@@ -189,8 +189,9 @@ func TestGeminiEngineExecution(t *testing.T) {
 
 		stepContent := strings.Join(steps[0], "\n")
 
-		assert.Contains(t, stepContent, "--mcp-config /tmp/gh-aw/mcp-config/mcp-servers.json", "Should include MCP config")
-		assert.Contains(t, stepContent, "GH_AW_MCP_CONFIG: /tmp/gh-aw/mcp-config/mcp-servers.json", "Should set MCP config env var")
+		// Gemini CLI reads MCP config from .gemini/settings.json, not --mcp-config flag
+		assert.NotContains(t, stepContent, "--mcp-config", "Should NOT include --mcp-config flag (Gemini CLI does not support it)")
+		assert.Contains(t, stepContent, "GH_AW_MCP_CONFIG: ${{ github.workspace }}/.gemini/settings.json", "Should set MCP config env var to Gemini settings.json path")
 	})
 
 	t.Run("with custom command", func(t *testing.T) {

tmp-smoke-test-22204310776.txt

@@ -0,0 +1 @@
+Smoke test file for PR push test - Run 22204310776