diff --git a/README.md b/README.md
index 715ef16..21c5b4a 100644
--- a/README.md
+++ b/README.md
@@ -137,27 +137,69 @@ The sandbox mode allows you to safely test code changes, run scripts, or execute
 
 These tools are designed to be used by the AI assistant.
 
-- **`ask-gemini`**: Asks Google Gemini for its perspective. Can be used for general questions or complex analysis of files.
+- **`ask-gemini`**: Execute Gemini CLI with full feature support including advanced flags, caching, and change mode.
   - **`prompt`** (required): The analysis request. Use the `@` syntax to include file or directory references (e.g., `@src/main.js explain this code`) or ask general questions (e.g., `Please use a web search to find the latest news stories`).
-  - **`model`** (optional): The Gemini model to use. Defaults to `gemini-2.5-pro`.
+  - **`model`** (optional): The Gemini model to use. Defaults to `gemini-2.5-pro`. Use `gemini-2.5-flash` for faster responses.
   - **`sandbox`** (optional): Set to `true` to run in sandbox mode for safe code execution.
-- **`sandbox-test`**: Safely executes code or commands in Gemini's sandbox environment. Always runs in sandbox mode.
-  - **`prompt`** (required): Code testing request (e.g., `Create and run a Python script that...` or `@script.py Run this safely`).
+  - **`changeMode`** (optional): Enable structured change mode for edit suggestions that Claude can apply directly.
+  - **`yolo`** (optional): Auto-accept all actions (YOLO mode). Use with caution.
+  - **`approvalMode`** (optional): Fine-grained approval control: `default`, `auto_edit`, or `yolo`.
+  - **`outputFormat`** (optional): Control output format: `text`, `json`, or `stream-json`.
+  - **`includeDirectories`** (optional): Additional directories to include in workspace.
+  - **`debug`** (optional): Enable verbose logging for troubleshooting.
+  - **`promptInteractive`** (optional): Execute prompt and continue in interactive mode.
+  - **`extensions`** (optional): Filter specific file extensions.
+  - **`resume`** (optional): Resume previous session (use `latest` or session number).
+
+- **`brainstorm`**: Generate creative ideas with structured methodologies and domain context.
+  - **`prompt`** (required): Brainstorming challenge or question to explore.
   - **`model`** (optional): The Gemini model to use.
-- **`Ping`**: A simple test tool that echoes back a message.
-- **`Help`**: Shows the Gemini CLI help text.
+  - **`methodology`** (optional): Framework to use: `divergent`, `convergent`, `scamper`, `design-thinking`, `lateral`, or `auto` (default).
+  - **`domain`** (optional): Domain context (e.g., 'software', 'business', 'creative', 'research').
+  - **`constraints`** (optional): Known limitations or requirements.
+  - **`ideaCount`** (optional): Number of ideas to generate (default: 12).
+  - **`includeAnalysis`** (optional): Include feasibility and impact analysis (default: true).
+
+- **`fetch-chunk`**: Retrieve cached chunks from large changeMode responses.
+  - **`cacheKey`** (required): Cache key from initial changeMode response.
+  - **`chunkIndex`** (required): Chunk number to retrieve (1-based index).
+
+- **`ping`**: Echo test message to verify server connection.
+  - **`prompt`** (optional): Message to echo back.
+
+- **`Help`**: Display Gemini CLI help information.
 
 ### Slash Commands (for the User)
 
 You can use these commands directly in Claude Code's interface (compatibility with other clients has not been tested).
 
-- **/analyze**: Analyzes files or directories using Gemini, or asks general questions.
-  - **`prompt`** (required): The analysis prompt. Use `@` syntax to include files (e.g., `/analyze prompt:@src/ summarize this directory`) or ask general questions (e.g., `/analyze prompt:Please use a web search to find the latest news stories`).
-- **/sandbox**: Safely tests code or scripts in Gemini's sandbox environment.
-  - **`prompt`** (required): Code testing request (e.g., `/sandbox prompt:Create and run a Python script that processes CSV data` or `/sandbox prompt:@script.py Test this script safely`).
-- **/help**: Displays the Gemini CLI help information.
-- **/ping**: Tests the connection to the server.
-  - **`message`** (optional): A message to echo back.
+- **/ask-gemini**: Execute Gemini CLI with advanced features and caching.
+  - **Example**: `/ask-gemini prompt:@src/ summarize this directory`
+  - **With sandbox**: `/ask-gemini prompt:@script.py test this safely sandbox:true`
+  - **With change mode**: `/ask-gemini prompt:Refactor this code changeMode:true`
+  - **Supports all flags**: yolo, approvalMode, outputFormat, debug, etc.
+
+- **/brainstorm**: Generate structured ideas with creative methodologies.
+  - **Example**: `/brainstorm prompt:How can we improve user onboarding? methodology:design-thinking domain:software`
+  - **Quick use**: `/brainstorm prompt:Ideas for a mobile app feature`
+
+- **/fetch-chunk**: Retrieve next chunk of a large changeMode response.
+  - **Example**: `/fetch-chunk cacheKey:abc123 chunkIndex:2`
+
+- **/Help**: Display Gemini CLI help information.
+  - **Example**: `/Help`
+
+- **/ping**: Test the MCP server connection.
+  - **Example**: `/ping prompt:Hello server!`
+
+## Performance Features
+
+This MCP server includes several performance optimizations:
+
+- **LRU Response Cache**: Near-instant responses for repeated queries with 30-minute TTL and 10MB max size
+- **Efficient Command Execution**: O(n) array buffer performance for large outputs
+- **Smart Chunking**: Large changeMode responses are automatically chunked for better handling
+- **Progress Notifications**: Real-time progress updates during long-running operations
 
 ## Contributing
 
diff --git a/package-lock.json b/package-lock.json
index 17a2766..a382408 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -14,6 +14,7 @@
         "chalk": "^5.0.0",
         "d3-shape": "^3.2.0",
         "inquirer": "^9.0.0",
+        "lru-cache": "^11.2.4",
         "prismjs": "^1.30.0",
         "zod": "^3.25.76",
         "zod-to-json-schema": "^3.24.6"
@@ -26,7 +27,6 @@
         "@types/node": "^20.0.0",
         "archiver": "^7.0.1",
         "mermaid": "^11.9.0",
-        "nodemon": "^3.1.10",
         "tsx": "^4.0.0",
         "typescript": "^5.0.0",
         "vitepress": "^1.6.3",
@@ -251,6 +251,7 @@
       "integrity": "sha512-cZ0Iq3OzFUPpgszzDr1G1aJV5UMIZ4VygJ2Az252q4Rdf5cQMhYEIKArWY/oUjMhQmosM8ygOovNq7gvA9CdCg==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@algolia/client-common": "5.29.0",
         "@algolia/requester-browser-xhr": "5.29.0",
@@ -2267,6 +2268,7 @@
       "integrity": "sha512-E2l6AlTWGznM2e7vEE6T6hzObvEyXukxMOlBmVlMyixZyK1umuO/CiVc6sDBbzVH0oEviCE5IfVY1oZBmccYPQ==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@algolia/client-abtesting": "5.29.0",
         "@algolia/client-analytics": "5.29.0",
@@ -2325,20 +2327,6 @@
         "url": "https://github.com/chalk/ansi-styles?sponsor=1"
       }
     },
-    "node_modules/anymatch": {
-      "version": "3.1.3",
-      "resolved": "https://registry.npmjs.org/anymatch/-/anymatch-3.1.3.tgz",
-      "integrity": "sha512-KMReFUr0B4t+D+OBkjR3KYqvocp2XaSzO55UcB6mgQMd3KbcE+mWTyvVV7D/zsdEbNnV6acZUutkiHQXvTr1Rw==",
-      "dev": true,
-      "license": "ISC",
-      "dependencies": {
-        "normalize-path": "^3.0.0",
-        "picomatch": "^2.0.4"
-      },
-      "engines": {
-        "node": ">= 8"
-      }
-    },
     "node_modules/archiver": {
       "version": "7.0.1",
       "resolved": "https://registry.npmjs.org/archiver/-/archiver-7.0.1.tgz",
@@ -2510,19 +2498,6 @@
       ],
       "license": "MIT"
     },
-    "node_modules/binary-extensions": {
-      "version": "2.3.0",
-      "resolved": "https://registry.npmjs.org/binary-extensions/-/binary-extensions-2.3.0.tgz",
-      "integrity": "sha512-Ceh+7ox5qe7LJuLHoY0feh3pHuUDHAcRUeyL2VYghZwfpkNIy/+8Ocg0a3UuSoYzavmylwuLWQOf3hl0jjMMIw==",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">=8"
-      },
-      "funding": {
-        "url": "https://github.com/sponsors/sindresorhus"
-      }
-    },
     "node_modules/birpc": {
       "version": "2.4.0",
       "resolved": "https://registry.npmjs.org/birpc/-/birpc-2.4.0.tgz",
@@ -2554,19 +2529,6 @@
         "balanced-match": "^1.0.0"
       }
     },
-    "node_modules/braces": {
-      "version": "3.0.3",
-      "resolved": "https://registry.npmjs.org/braces/-/braces-3.0.3.tgz",
-      "integrity": "sha512-yQbXgO/OSZVD2IsiLlro+7Hf6Q18EJrKSEsdoMzKePKXct3gvD8oLcOQdIzGupr5Fj+EDe8gO/lxc1BzfMpxvA==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "fill-range": "^7.1.1"
-      },
-      "engines": {
-        "node": ">=8"
-      }
-    },
     "node_modules/buffer": {
       "version": "5.7.1",
       "resolved": "https://registry.npmjs.org/buffer/-/buffer-5.7.1.tgz",
@@ -2667,6 +2629,7 @@
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       "dev": true,
       "license": "Apache-2.0",
+      "peer": true,
       "dependencies": {
         "@chevrotain/cst-dts-gen": "11.0.3",
         "@chevrotain/gast": "11.0.3",
@@ -2689,31 +2652,6 @@
         "chevrotain": "^11.0.0"
       }
     },
-    "node_modules/chokidar": {
-      "version": "3.6.0",
-      "resolved": "https://registry.npmjs.org/chokidar/-/chokidar-3.6.0.tgz",
-      "integrity": "sha512-7VT13fmjotKpGipCW9JEQAusEPE+Ei8nl6/g4FBAmIm0GOOLMua9NDDo/DWp0ZAxCr3cPq5ZpBqmPAQgDda2Pw==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "anymatch": "~3.1.2",
-        "braces": "~3.0.2",
-        "glob-parent": "~5.1.2",
-        "is-binary-path": "~2.1.0",
-        "is-glob": "~4.0.1",
-        "normalize-path": "~3.0.0",
-        "readdirp": "~3.6.0"
-      },
-      "engines": {
-        "node": ">= 8.10.0"
-      },
-      "funding": {
-        "url": "https://paulmillr.com/funding/"
-      },
-      "optionalDependencies": {
-        "fsevents": "~2.3.2"
-      }
-    },
     "node_modules/cli-cursor": {
       "version": "3.1.0",
       "resolved": "https://registry.npmjs.org/cli-cursor/-/cli-cursor-3.1.0.tgz",
@@ -2854,13 +2792,6 @@
         "node": "^12.22.0 || ^14.17.0 || >=16.0.0"
       }
     },
-    "node_modules/concat-map": {
-      "version": "0.0.1",
-      "resolved": "https://registry.npmjs.org/concat-map/-/concat-map-0.0.1.tgz",
-      "integrity": "sha512-/Srv4dswyQNBfohGpz9o6Yb3Gz3SrUDqBH5rTuhGR7ahtlbYKnVxw2bCFMRljaA7EXHaXZ8wsHdodFvbkhKmqg==",
-      "dev": true,
-      "license": "MIT"
-    },
     "node_modules/confbox": {
       "version": "0.2.2",
       "resolved": "https://registry.npmjs.org/confbox/-/confbox-0.2.2.tgz",
@@ -3007,6 +2938,7 @@
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       "dev": true,
       "license": "MIT",
+      "peer": true,
       "engines": {
         "node": ">=0.10"
       }
@@ -3440,6 +3372,7 @@
       "integrity": "sha512-fmTRWbNMmsmWq6xJV8D19U/gw/bwrHfNXxrIN+HfZgnzqTHp9jOmKMhsTUjXOJnZOdZY9Q28y4yebKzqDKlxlQ==",
       "dev": true,
       "license": "ISC",
+      "peer": true,
       "engines": {
         "node": ">=12"
       }
@@ -3776,25 +3709,13 @@
       "dev": true,
       "license": "MIT"
     },
-    "node_modules/fill-range": {
-      "version": "7.1.1",
-      "resolved": "https://registry.npmjs.org/fill-range/-/fill-range-7.1.1.tgz",
-      "integrity": "sha512-YsGpe3WHLK8ZYi4tWDg2Jy3ebRz2rXowDxnld4bkQB00cc/1Zw9AWnC0i9ztDJitivtQvaI9KaLyKrc+hBW0yg==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "to-regex-range": "^5.0.1"
-      },
-      "engines": {
-        "node": ">=8"
-      }
-    },
     "node_modules/focus-trap": {
       "version": "7.6.5",
       "resolved": "https://registry.npmjs.org/focus-trap/-/focus-trap-7.6.5.tgz",
       "integrity": "sha512-7Ke1jyybbbPZyZXFxEftUtxFGLMpE2n6A+z//m4CRDlj0hW+o3iYSmh8nFlYMurOiJVDmJRilUQtJr08KfIxlg==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "tabbable": "^6.2.0"
       }
@@ -3878,19 +3799,6 @@
         "url": "https://github.com/sponsors/isaacs"
       }
     },
-    "node_modules/glob-parent": {
-      "version": "5.1.2",
-      "resolved": "https://registry.npmjs.org/glob-parent/-/glob-parent-5.1.2.tgz",
-      "integrity": "sha512-AOIgSQCepiJYwP3ARnGx+5VnTu2HBYdzbGP45eLw1vr3zB3vZLeyed1sC9hnbcOc9/SrMyM5RPQrkGz4aS9Zow==",
-      "dev": true,
-      "license": "ISC",
-      "dependencies": {
-        "is-glob": "^4.0.1"
-      },
-      "engines": {
-        "node": ">= 6"
-      }
-    },
     "node_modules/globals": {
       "version": "15.15.0",
       "resolved": "https://registry.npmjs.org/globals/-/globals-15.15.0.tgz",
@@ -4031,13 +3939,6 @@
       ],
       "license": "BSD-3-Clause"
     },
-    "node_modules/ignore-by-default": {
-      "version": "1.0.1",
-      "resolved": "https://registry.npmjs.org/ignore-by-default/-/ignore-by-default-1.0.1.tgz",
-      "integrity": "sha512-Ius2VYcGNk7T90CppJqcIkS5ooHUZyIQK+ClZfMfMNFEF9VSE73Fq+906u/CWu92x4gzZMWOwfFYckPObzdEbA==",
-      "dev": true,
-      "license": "ISC"
-    },
     "node_modules/inherits": {
       "version": "2.0.4",
       "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.4.tgz",
@@ -4077,29 +3978,6 @@
         "node": ">=12"
       }
     },
-    "node_modules/is-binary-path": {
-      "version": "2.1.0",
-      "resolved": "https://registry.npmjs.org/is-binary-path/-/is-binary-path-2.1.0.tgz",
-      "integrity": "sha512-ZMERYes6pDydyuGidse7OsHxtbI7WVeUEozgR/g7rd0xUimYNlvZRE/K2MgZTjWy725IfelLeVcEM97mmtRGXw==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "binary-extensions": "^2.0.0"
-      },
-      "engines": {
-        "node": ">=8"
-      }
-    },
-    "node_modules/is-extglob": {
-      "version": "2.1.1",
-      "resolved": "https://registry.npmjs.org/is-extglob/-/is-extglob-2.1.1.tgz",
-      "integrity": "sha512-SbKbANkN603Vi4jEZv49LeVJMn4yGwsbzZworEoyEiutsN3nJYdbO36zfhGJ6QEDpOZIFkDtnq5JRxmvl3jsoQ==",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">=0.10.0"
-      }
-    },
     "node_modules/is-fullwidth-code-point": {
       "version": "3.0.0",
       "resolved": "https://registry.npmjs.org/is-fullwidth-code-point/-/is-fullwidth-code-point-3.0.0.tgz",
@@ -4109,19 +3987,6 @@
         "node": ">=8"
       }
     },
-    "node_modules/is-glob": {
-      "version": "4.0.3",
-      "resolved": "https://registry.npmjs.org/is-glob/-/is-glob-4.0.3.tgz",
-      "integrity": "sha512-xelSayHH36ZgE7ZWhli7pW34hNbNl8Ojv5KVmkJD4hBdD3th8Tfk9vYasLM+mXWOZhFkgZfxhLSnrwRr4elSSg==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "is-extglob": "^2.1.1"
-      },
-      "engines": {
-        "node": ">=0.10.0"
-      }
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     "node_modules/is-interactive": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/is-interactive/-/is-interactive-1.0.0.tgz",
@@ -4131,16 +3996,6 @@
         "node": ">=8"
       }
     },
-    "node_modules/is-number": {
-      "version": "7.0.0",
-      "resolved": "https://registry.npmjs.org/is-number/-/is-number-7.0.0.tgz",
-      "integrity": "sha512-41Cifkg6e8TylSpdtTpeLVMqvSBEVzTttHvERD741+pnZ8ANv0004MRL43QKPDlK9cGvNp6NZWZUBlbGXYxxng==",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">=0.12.0"
-      }
-    },
     "node_modules/is-stream": {
       "version": "2.0.1",
       "resolved": "https://registry.npmjs.org/is-stream/-/is-stream-2.0.1.tgz",
@@ -4213,8 +4068,7 @@
       "version": "4.0.0",
       "resolved": "https://registry.npmjs.org/js-tokens/-/js-tokens-4.0.0.tgz",
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-      "license": "MIT",
-      "peer": true
+      "license": "MIT"
     },
     "node_modules/json-schema": {
       "version": "0.4.0",
@@ -4418,7 +4272,6 @@
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       "license": "MIT",
-      "peer": true,
       "dependencies": {
         "js-tokens": "^3.0.0 || ^4.0.0"
       },
@@ -4427,11 +4280,13 @@
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-      "version": "10.4.3",
-      "resolved": "https://registry.npmjs.org/lru-cache/-/lru-cache-10.4.3.tgz",
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-      "dev": true,
-      "license": "ISC"
+      "version": "11.2.4",
+      "resolved": "https://registry.npmjs.org/lru-cache/-/lru-cache-11.2.4.tgz",
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+      "license": "BlueOak-1.0.0",
+      "engines": {
+        "node": "20 || >=22"
+      }
     },
     "node_modules/magic-string": {
       "version": "0.30.17",
@@ -4491,6 +4346,7 @@
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       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@braintree/sanitize-url": "^7.0.4",
         "@iconify/utils": "^2.1.33",
@@ -4723,82 +4579,6 @@
         "node": "^10 || ^12 || ^13.7 || ^14 || >=15.0.1"
       }
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-    "node_modules/nodemon": {
-      "version": "3.1.10",
-      "resolved": "https://registry.npmjs.org/nodemon/-/nodemon-3.1.10.tgz",
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-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "chokidar": "^3.5.2",
-        "debug": "^4",
-        "ignore-by-default": "^1.0.1",
-        "minimatch": "^3.1.2",
-        "pstree.remy": "^1.1.8",
-        "semver": "^7.5.3",
-        "simple-update-notifier": "^2.0.0",
-        "supports-color": "^5.5.0",
-        "touch": "^3.1.0",
-        "undefsafe": "^2.0.5"
-      },
-      "bin": {
-        "nodemon": "bin/nodemon.js"
-      },
-      "engines": {
-        "node": ">=10"
-      },
-      "funding": {
-        "type": "opencollective",
-        "url": "https://opencollective.com/nodemon"
-      }
-    },
-    "node_modules/nodemon/node_modules/brace-expansion": {
-      "version": "1.1.12",
-      "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-1.1.12.tgz",
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-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "balanced-match": "^1.0.0",
-        "concat-map": "0.0.1"
-      }
-    },
-    "node_modules/nodemon/node_modules/has-flag": {
-      "version": "3.0.0",
-      "resolved": "https://registry.npmjs.org/has-flag/-/has-flag-3.0.0.tgz",
-      "integrity": "sha512-sKJf1+ceQBr4SMkvQnBDNDtf4TXpVhVGateu0t918bl30FnbE2m4vNLX+VWe/dpjlb+HugGYzW7uQXH98HPEYw==",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">=4"
-      }
-    },
-    "node_modules/nodemon/node_modules/minimatch": {
-      "version": "3.1.2",
-      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.1.2.tgz",
-      "integrity": "sha512-J7p63hRiAjw1NDEww1W7i37+ByIrOWO5XQQAzZ3VOcL0PNybwpfmV/N05zFAzwQ9USyEcX6t3UO+K5aqBQOIHw==",
-      "dev": true,
-      "license": "ISC",
-      "dependencies": {
-        "brace-expansion": "^1.1.7"
-      },
-      "engines": {
-        "node": "*"
-      }
-    },
-    "node_modules/nodemon/node_modules/supports-color": {
-      "version": "5.5.0",
-      "resolved": "https://registry.npmjs.org/supports-color/-/supports-color-5.5.0.tgz",
-      "integrity": "sha512-QjVjwdXIt408MIiAqCX4oUKsgU2EqAGzs2Ppkm4aQYbjm+ZEWEcW4SfFNTr4uMNZma0ey4f5lgLrkB0aX0QMow==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "has-flag": "^3.0.0"
-      },
-      "engines": {
-        "node": ">=4"
-      }
-    },
     "node_modules/non-layered-tidy-tree-layout": {
       "version": "2.0.2",
       "resolved": "https://registry.npmjs.org/non-layered-tidy-tree-layout/-/non-layered-tidy-tree-layout-2.0.2.tgz",
@@ -4940,6 +4720,13 @@
         "url": "https://github.com/sponsors/isaacs"
       }
     },
+    "node_modules/path-scurry/node_modules/lru-cache": {
+      "version": "10.4.3",
+      "resolved": "https://registry.npmjs.org/lru-cache/-/lru-cache-10.4.3.tgz",
+      "integrity": "sha512-JNAzZcXrCt42VGLuYz0zfAzDfAvJWW6AfYlDBQyDV5DClI2m5sAmK+OIO7s59XfsRsWHp02jAJrRadPRGTt6SQ==",
+      "dev": true,
+      "license": "ISC"
+    },
     "node_modules/pathe": {
       "version": "2.0.3",
       "resolved": "https://registry.npmjs.org/pathe/-/pathe-2.0.3.tgz",
@@ -4961,19 +4748,6 @@
       "dev": true,
       "license": "ISC"
     },
-    "node_modules/picomatch": {
-      "version": "2.3.1",
-      "resolved": "https://registry.npmjs.org/picomatch/-/picomatch-2.3.1.tgz",
-      "integrity": "sha512-JU3teHTNjmE2VCGFzuY8EXzCDVwEqB2a8fsIvwaStHhAWJEeVd1o1QD80CU6+ZdEXXSLbSsuLwJjkCBWqRQUVA==",
-      "dev": true,
-      "license": "MIT",
-      "engines": {
-        "node": ">=8.6"
-      },
-      "funding": {
-        "url": "https://github.com/sponsors/jonschlinkert"
-      }
-    },
     "node_modules/pkg-types": {
       "version": "2.2.0",
       "resolved": "https://registry.npmjs.org/pkg-types/-/pkg-types-2.2.0.tgz",
@@ -5081,13 +4855,6 @@
         "url": "https://github.com/sponsors/wooorm"
       }
     },
-    "node_modules/pstree.remy": {
-      "version": "1.1.8",
-      "resolved": "https://registry.npmjs.org/pstree.remy/-/pstree.remy-1.1.8.tgz",
-      "integrity": "sha512-77DZwxQmxKnu3aR542U+X8FypNzbfJ+C5XQDk3uWjWxn6151aIMGthWYRXTqT1E5oJvg+ljaa2OJi+VfvCOQ8w==",
-      "dev": true,
-      "license": "MIT"
-    },
     "node_modules/quansync": {
       "version": "0.2.10",
       "resolved": "https://registry.npmjs.org/quansync/-/quansync-0.2.10.tgz",
@@ -5170,19 +4937,6 @@
         "node": ">=10"
       }
     },
-    "node_modules/readdirp": {
-      "version": "3.6.0",
-      "resolved": "https://registry.npmjs.org/readdirp/-/readdirp-3.6.0.tgz",
-      "integrity": "sha512-hOS089on8RduqdbhvQ5Z37A0ESjsqz6qnRcffsMU3495FuTdqSm+7bhJ29JvIOsBDEEnan5DPu9t3To9VRlMzA==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "picomatch": "^2.2.1"
-      },
-      "engines": {
-        "node": ">=8.10.0"
-      }
-    },
     "node_modules/regex": {
       "version": "6.0.1",
       "resolved": "https://registry.npmjs.org/regex/-/regex-6.0.1.tgz",
@@ -5365,19 +5119,6 @@
       "integrity": "sha512-6aU+Rwsezw7VR8/nyvKTx8QpWH9FrcYiXXlqC4z5d5XQBDRqtbfsRjnwGyqbi3gddNtWHuEk9OANUotL26qKUw==",
       "license": "BSD-3-Clause"
     },
-    "node_modules/semver": {
-      "version": "7.7.2",
-      "resolved": "https://registry.npmjs.org/semver/-/semver-7.7.2.tgz",
-      "integrity": "sha512-RF0Fw+rO5AMf9MAyaRXI4AV0Ulj5lMHqVxxdSgiVbixSCXoEmmX/jk0CuJw4+3SqroYO9VoUh+HcuJivvtJemA==",
-      "dev": true,
-      "license": "ISC",
-      "bin": {
-        "semver": "bin/semver.js"
-      },
-      "engines": {
-        "node": ">=10"
-      }
-    },
     "node_modules/setprototypeof": {
       "version": "1.2.0",
       "resolved": "https://registry.npmjs.org/setprototypeof/-/setprototypeof-1.2.0.tgz",
@@ -5430,19 +5171,6 @@
       "integrity": "sha512-wnD2ZE+l+SPC/uoS0vXeE9L1+0wuaMqKlfz9AMUo38JsyLSBWSFcHR1Rri62LZc12vLr1gb3jl7iwQhgwpAbGQ==",
       "license": "ISC"
     },
-    "node_modules/simple-update-notifier": {
-      "version": "2.0.0",
-      "resolved": "https://registry.npmjs.org/simple-update-notifier/-/simple-update-notifier-2.0.0.tgz",
-      "integrity": "sha512-a2B9Y0KlNXl9u/vsW6sTIu9vGEpfKu2wRV6l1H3XEas/0gUIzGzBoP/IouTcUQbm9JWZLH3COxyn03TYlFax6w==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "semver": "^7.5.3"
-      },
-      "engines": {
-        "node": ">=10"
-      }
-    },
     "node_modules/source-map-js": {
       "version": "1.2.1",
       "resolved": "https://registry.npmjs.org/source-map-js/-/source-map-js-1.2.1.tgz",
@@ -5682,19 +5410,6 @@
         "node": ">=0.6.0"
       }
     },
-    "node_modules/to-regex-range": {
-      "version": "5.0.1",
-      "resolved": "https://registry.npmjs.org/to-regex-range/-/to-regex-range-5.0.1.tgz",
-      "integrity": "sha512-65P7iz6X5yEr1cwcgvQxbbIw7Uk3gOy5dIdtZ4rDveLqhrdJP+Li/Hx6tyK0NEb+2GCyneCMJiGqrADCSNk8sQ==",
-      "dev": true,
-      "license": "MIT",
-      "dependencies": {
-        "is-number": "^7.0.0"
-      },
-      "engines": {
-        "node": ">=8.0"
-      }
-    },
     "node_modules/toidentifier": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/toidentifier/-/toidentifier-1.0.1.tgz",
@@ -5704,16 +5419,6 @@
         "node": ">=0.6"
       }
     },
-    "node_modules/touch": {
-      "version": "3.1.1",
-      "resolved": "https://registry.npmjs.org/touch/-/touch-3.1.1.tgz",
-      "integrity": "sha512-r0eojU4bI8MnHr8c5bNo7lJDdI2qXlWWJk6a9EAFG7vbhTjElYhBVS3/miuE0uOuoLdb8Mc/rVfsmm6eo5o9GA==",
-      "dev": true,
-      "license": "ISC",
-      "bin": {
-        "nodetouch": "bin/nodetouch.js"
-      }
-    },
     "node_modules/trim-lines": {
       "version": "3.0.1",
       "resolved": "https://registry.npmjs.org/trim-lines/-/trim-lines-3.0.1.tgz",
@@ -5779,6 +5484,7 @@
       "integrity": "sha512-p1diW6TqL9L07nNxvRMM7hMMw4c5XOo/1ibL4aAIGmSAt9slTE1Xgw5KWuof2uTOvCg9BY7ZRi+GaF+7sfgPeQ==",
       "dev": true,
       "license": "Apache-2.0",
+      "peer": true,
       "bin": {
         "tsc": "bin/tsc",
         "tsserver": "bin/tsserver"
@@ -5794,13 +5500,6 @@
       "dev": true,
       "license": "MIT"
     },
-    "node_modules/undefsafe": {
-      "version": "2.0.5",
-      "resolved": "https://registry.npmjs.org/undefsafe/-/undefsafe-2.0.5.tgz",
-      "integrity": "sha512-WxONCrssBM8TSPRqN5EmsjVrsv4A8X12J4ArBiiayv3DyyG3ZlIg6yysuuSYdZsVz3TKcTg2fd//Ujd4CHV1iA==",
-      "dev": true,
-      "license": "MIT"
-    },
     "node_modules/undici-types": {
       "version": "6.21.0",
       "resolved": "https://registry.npmjs.org/undici-types/-/undici-types-6.21.0.tgz",
@@ -5955,6 +5654,7 @@
       "integrity": "sha512-qO3aKv3HoQC8QKiNSTuUM1l9o/XX3+c+VTgLHbJWHZGeTPVAg2XwazI9UWzoxjIJCGCV2zU60uqMzjeLZuULqA==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "esbuild": "^0.21.3",
         "postcss": "^8.4.43",
@@ -6445,6 +6145,7 @@
       "integrity": "sha512-fCkfdOk8yRZT8GD9BFqusW3+GggWYZ/rYncOfmgcDtP3ualNHCAg+Robxp2/6xfH1WwPHtGpPwv7mbA3qomtBw==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@docsearch/css": "3.8.2",
         "@docsearch/js": "3.8.2",
@@ -6556,6 +6257,7 @@
       "integrity": "sha512-LbHV3xPN9BeljML+Xctq4lbz2lVHCR6DtbpTf5XIO6gugpXUN49j2QQPcMj086r9+AkJ0FfUT8xjulKKBkkr9g==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "@vue/compiler-dom": "3.5.17",
         "@vue/compiler-sfc": "3.5.17",
@@ -6704,6 +6406,7 @@
       "resolved": "https://registry.npmjs.org/zod/-/zod-3.25.76.tgz",
       "integrity": "sha512-gzUt/qt81nXsFGKIFcC3YnfEAx5NkunCfnDlvuBSSFS02bcXu4Lmea0AFIUwbLWxWPx3d9p8S5QoaujKcNQxcQ==",
       "license": "MIT",
+      "peer": true,
       "funding": {
         "url": "https://github.com/sponsors/colinhacks"
       }
diff --git a/package.json b/package.json
index 2a547c7..7304823 100644
--- a/package.json
+++ b/package.json
@@ -11,7 +11,9 @@
     "build": "tsc",
     "start": "node dist/index.js",
     "dev": "tsc && node dist/index.js",
-    "test": "echo \"No tests yet\" && exit 0",
+    "test": "vitest run",
+    "test:watch": "vitest watch",
+    "test:coverage": "vitest run --coverage",
     "lint": "tsc --noEmit",
     "contribute": "tsx src/contribute.ts",
     "prepublishOnly": "echo '⚠️  Remember to test locally first!' && npm run build",
@@ -51,6 +53,7 @@
     "chalk": "^5.0.0",
     "d3-shape": "^3.2.0",
     "inquirer": "^9.0.0",
+    "lru-cache": "^11.2.4",
     "prismjs": "^1.30.0",
     "zod": "^3.25.76",
     "zod-to-json-schema": "^3.24.6"
@@ -58,12 +61,14 @@
   "devDependencies": {
     "@types/inquirer": "^9.0.0",
     "@types/node": "^20.0.0",
+    "@vitest/coverage-v8": "^2.1.8",
     "archiver": "^7.0.1",
     "mermaid": "^11.9.0",
     "tsx": "^4.0.0",
     "typescript": "^5.0.0",
     "vitepress": "^1.6.3",
-    "vitepress-plugin-mermaid": "^2.0.17"
+    "vitepress-plugin-mermaid": "^2.0.17",
+    "vitest": "^2.1.8"
   },
   "publishConfig": {
     "access": "public"
diff --git a/src/__tests__/ask-gemini.test.ts b/src/__tests__/ask-gemini.test.ts
new file mode 100644
index 0000000..b268ebe
--- /dev/null
+++ b/src/__tests__/ask-gemini.test.ts
@@ -0,0 +1,187 @@
+import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { z } from 'zod';
+
+describe('ask-gemini Tool', () => {
+  describe('Argument Schema Validation', () => {
+    const askGeminiArgsSchema = z.object({
+      prompt: z.string().min(1),
+      model: z.string().optional(),
+      sandbox: z.boolean().default(false),
+      changeMode: z.boolean().default(false),
+      chunkIndex: z.union([z.number(), z.string()]).optional(),
+      chunkCacheKey: z.string().optional(),
+      yolo: z.boolean().default(false),
+      approvalMode: z.enum(['default', 'auto_edit', 'yolo']).optional(),
+      outputFormat: z.enum(['text', 'json', 'stream-json']).optional(),
+      includeDirectories: z.union([z.string(), z.array(z.string())]).optional(),
+      debug: z.boolean().default(false),
+      promptInteractive: z.string().optional(),
+      extensions: z.union([z.string(), z.array(z.string())]).optional(),
+      resume: z.string().optional(),
+    });
+
+    it('should accept valid minimal arguments', () => {
+      const result = askGeminiArgsSchema.parse({ prompt: 'test prompt' });
+      expect(result.prompt).toBe('test prompt');
+      expect(result.sandbox).toBe(false);
+      expect(result.changeMode).toBe(false);
+    });
+
+    it('should accept all optional flags', () => {
+      const result = askGeminiArgsSchema.parse({
+        prompt: 'test prompt',
+        model: 'gemini-2.5-flash',
+        sandbox: true,
+        changeMode: true,
+        yolo: true,
+        approvalMode: 'auto_edit',
+        outputFormat: 'json',
+        debug: true,
+      });
+
+      expect(result.model).toBe('gemini-2.5-flash');
+      expect(result.sandbox).toBe(true);
+      expect(result.changeMode).toBe(true);
+      expect(result.yolo).toBe(true);
+      expect(result.approvalMode).toBe('auto_edit');
+      expect(result.outputFormat).toBe('json');
+      expect(result.debug).toBe(true);
+    });
+
+    it('should reject missing prompt', () => {
+      expect(() => askGeminiArgsSchema.parse({})).toThrow();
+    });
+
+    it('should reject empty prompt', () => {
+      expect(() => askGeminiArgsSchema.parse({ prompt: '' })).toThrow();
+    });
+
+    it('should reject invalid approval mode', () => {
+      expect(() =>
+        askGeminiArgsSchema.parse({
+          prompt: 'test',
+          approvalMode: 'invalid',
+        })
+      ).toThrow();
+    });
+
+    it('should reject invalid output format', () => {
+      expect(() =>
+        askGeminiArgsSchema.parse({
+          prompt: 'test',
+          outputFormat: 'invalid',
+        })
+      ).toThrow();
+    });
+
+    it('should accept includeDirectories as string', () => {
+      const result = askGeminiArgsSchema.parse({
+        prompt: 'test',
+        includeDirectories: 'src,tests',
+      });
+      expect(result.includeDirectories).toBe('src,tests');
+    });
+
+    it('should accept includeDirectories as array', () => {
+      const result = askGeminiArgsSchema.parse({
+        prompt: 'test',
+        includeDirectories: ['src', 'tests'],
+      });
+      expect(result.includeDirectories).toEqual(['src', 'tests']);
+    });
+
+    it('should accept extensions as string', () => {
+      const result = askGeminiArgsSchema.parse({
+        prompt: 'test',
+        extensions: 'ts,js',
+      });
+      expect(result.extensions).toBe('ts,js');
+    });
+
+    it('should accept extensions as array', () => {
+      const result = askGeminiArgsSchema.parse({
+        prompt: 'test',
+        extensions: ['ts', 'js'],
+      });
+      expect(result.extensions).toEqual(['ts', 'js']);
+    });
+
+    it('should accept resume parameter', () => {
+      const result = askGeminiArgsSchema.parse({
+        prompt: 'test',
+        resume: 'latest',
+      });
+      expect(result.resume).toBe('latest');
+    });
+
+    it('should accept chunkIndex as number', () => {
+      const result = askGeminiArgsSchema.parse({
+        prompt: 'test',
+        chunkIndex: 1,
+      });
+      expect(result.chunkIndex).toBe(1);
+    });
+
+    it('should accept chunkIndex as string', () => {
+      const result = askGeminiArgsSchema.parse({
+        prompt: 'test',
+        chunkIndex: '1',
+      });
+      expect(result.chunkIndex).toBe('1');
+    });
+  });
+
+  describe('Flag Combinations', () => {
+    const askGeminiArgsSchema = z.object({
+      prompt: z.string().min(1),
+      sandbox: z.boolean().default(false),
+      yolo: z.boolean().default(false),
+      approvalMode: z.enum(['default', 'auto_edit', 'yolo']).optional(),
+    });
+
+    it('should allow sandbox with yolo', () => {
+      const result = askGeminiArgsSchema.parse({
+        prompt: 'test',
+        sandbox: true,
+        yolo: true,
+      });
+      expect(result.sandbox).toBe(true);
+      expect(result.yolo).toBe(true);
+    });
+
+    it('should allow approvalMode to override yolo', () => {
+      const result = askGeminiArgsSchema.parse({
+        prompt: 'test',
+        yolo: true,
+        approvalMode: 'auto_edit',
+      });
+      expect(result.yolo).toBe(true);
+      expect(result.approvalMode).toBe('auto_edit');
+      // Note: In actual implementation, approvalMode should take precedence
+    });
+  });
+
+  describe('Error Messages', () => {
+    const askGeminiArgsSchema = z.object({
+      prompt: z.string().min(1),
+    });
+
+    it('should provide clear error for missing prompt', () => {
+      try {
+        askGeminiArgsSchema.parse({});
+      } catch (error: any) {
+        expect(error.issues[0].path).toContain('prompt');
+        expect(error.issues[0].message).toMatch(/required/i);
+      }
+    });
+
+    it('should provide clear error for empty prompt', () => {
+      try {
+        askGeminiArgsSchema.parse({ prompt: '' });
+      } catch (error: any) {
+        expect(error.issues[0].path).toContain('prompt');
+        expect(error.issues[0].message).toMatch(/at least 1/i);
+      }
+    });
+  });
+});
diff --git a/src/__tests__/server.test.ts b/src/__tests__/server.test.ts
new file mode 100644
index 0000000..989b46f
--- /dev/null
+++ b/src/__tests__/server.test.ts
@@ -0,0 +1,96 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
+import { Server } from '@modelcontextprotocol/sdk/server/index.js';
+import { StdioServerTransport } from '@modelcontextprotocol/sdk/server/stdio.js';
+
+// Mock dependencies
+vi.mock('@modelcontextprotocol/sdk/server/index.js', () => ({
+  Server: vi.fn().mockImplementation(() => ({
+    setRequestHandler: vi.fn(),
+    connect: vi.fn(),
+    notification: vi.fn(),
+  })),
+}));
+
+vi.mock('@modelcontextprotocol/sdk/server/stdio.js', () => ({
+  StdioServerTransport: vi.fn(),
+}));
+
+describe('Gemini MCP Server', () => {
+  let consoleErrorSpy: any;
+  let consoleDebugSpy: any;
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+    consoleErrorSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
+    consoleDebugSpy = vi.spyOn(console, 'log').mockImplementation(() => {});
+  });
+
+  afterEach(() => {
+    consoleErrorSpy.mockRestore();
+    consoleDebugSpy.mockRestore();
+  });
+
+  describe('Server Initialization', () => {
+    it('should create server with correct name and version', () => {
+      // Import will initialize the server
+      const mockServer = vi.mocked(Server).mock.results[0];
+      expect(Server).toHaveBeenCalled();
+
+      const serverConfig = vi.mocked(Server).mock.calls[0][0];
+      expect(serverConfig).toHaveProperty('name', 'gemini-cli-mcp');
+      expect(serverConfig).toHaveProperty('version');
+    });
+
+    it('should register capabilities', () => {
+      const serverConfig = vi.mocked(Server).mock.calls[0][1];
+      expect(serverConfig).toHaveProperty('capabilities');
+      expect(serverConfig.capabilities).toHaveProperty('tools');
+      expect(serverConfig.capabilities).toHaveProperty('prompts');
+    });
+  });
+
+  describe('Request Handlers', () => {
+    it('should register ListToolsRequestSchema handler', () => {
+      const mockServerInstance = vi.mocked(Server).mock.results[0].value;
+      expect(mockServerInstance.setRequestHandler).toHaveBeenCalled();
+
+      const calls = mockServerInstance.setRequestHandler.mock.calls;
+      const listToolsHandler = calls.find((call: any) =>
+        call[0]?.name === 'tools/list' || call[0]?.method === 'tools/list'
+      );
+
+      // At minimum, verify handler was registered
+      expect(calls.length).toBeGreaterThan(0);
+    });
+
+    it('should register CallToolRequestSchema handler', () => {
+      const mockServerInstance = vi.mocked(Server).mock.results[0].value;
+      const calls = mockServerInstance.setRequestHandler.mock.calls;
+
+      // Verify multiple handlers were registered
+      expect(calls.length).toBeGreaterThanOrEqual(2);
+    });
+
+    it('should register ListPromptsRequestSchema handler', () => {
+      const mockServerInstance = vi.mocked(Server).mock.results[0].value;
+      const calls = mockServerInstance.setRequestHandler.mock.calls;
+
+      // Verify prompts handler was registered
+      expect(calls.length).toBeGreaterThanOrEqual(3);
+    });
+  });
+
+  describe('Progress Notifications', () => {
+    it('should support progress notifications', () => {
+      const mockServerInstance = vi.mocked(Server).mock.results[0].value;
+      expect(mockServerInstance).toHaveProperty('notification');
+      expect(typeof mockServerInstance.notification).toBe('function');
+    });
+  });
+
+  describe('Transport Connection', () => {
+    it('should connect to StdioServerTransport', () => {
+      expect(StdioServerTransport).toHaveBeenCalled();
+    });
+  });
+});
diff --git a/src/__tests__/tools.test.ts b/src/__tests__/tools.test.ts
new file mode 100644
index 0000000..53eb1de
--- /dev/null
+++ b/src/__tests__/tools.test.ts
@@ -0,0 +1,162 @@
+import { describe, it, expect, beforeEach } from 'vitest';
+import { toolRegistry, getToolDefinitions, toolExists, getPromptDefinitions } from '../tools/registry.js';
+
+describe('Tool Registry', () => {
+  describe('getToolDefinitions', () => {
+    it('should return an array of tool definitions', () => {
+      const tools = getToolDefinitions();
+      expect(Array.isArray(tools)).toBe(true);
+      expect(tools.length).toBeGreaterThan(0);
+    });
+
+    it('should include ask-gemini tool', () => {
+      const tools = getToolDefinitions();
+      const askGeminiTool = tools.find(t => t.name === 'ask-gemini');
+
+      expect(askGeminiTool).toBeDefined();
+      expect(askGeminiTool?.description).toBeTruthy();
+      expect(askGeminiTool?.inputSchema).toBeDefined();
+    });
+
+    it('should include brainstorm tool', () => {
+      const tools = getToolDefinitions();
+      const brainstormTool = tools.find(t => t.name === 'brainstorm');
+
+      expect(brainstormTool).toBeDefined();
+      expect(brainstormTool?.description).toContain('brainstorm');
+    });
+
+    it('should include ping tool', () => {
+      const tools = getToolDefinitions();
+      const pingTool = tools.find(t => t.name === 'ping');
+
+      expect(pingTool).toBeDefined();
+    });
+
+    it('should include Help tool', () => {
+      const tools = getToolDefinitions();
+      const helpTool = tools.find(t => t.name === 'Help');
+
+      expect(helpTool).toBeDefined();
+    });
+
+    it('should include fetch-chunk tool', () => {
+      const tools = getToolDefinitions();
+      const fetchChunkTool = tools.find(t => t.name === 'fetch-chunk');
+
+      expect(fetchChunkTool).toBeDefined();
+    });
+
+    it('should have valid input schemas', () => {
+      const tools = getToolDefinitions();
+
+      tools.forEach(tool => {
+        expect(tool.inputSchema).toBeDefined();
+        expect(tool.inputSchema.type).toBe('object');
+        expect(tool.inputSchema).toHaveProperty('properties');
+        expect(tool.inputSchema).toHaveProperty('required');
+      });
+    });
+  });
+
+  describe('toolExists', () => {
+    it('should return true for existing tools', () => {
+      expect(toolExists('ask-gemini')).toBe(true);
+      expect(toolExists('brainstorm')).toBe(true);
+      expect(toolExists('ping')).toBe(true);
+      expect(toolExists('Help')).toBe(true);
+      expect(toolExists('fetch-chunk')).toBe(true);
+    });
+
+    it('should return false for non-existent tools', () => {
+      expect(toolExists('nonexistent-tool')).toBe(false);
+      expect(toolExists('fake-tool')).toBe(false);
+    });
+  });
+
+  describe('getPromptDefinitions', () => {
+    it('should return an array of prompt definitions', () => {
+      const prompts = getPromptDefinitions();
+      expect(Array.isArray(prompts)).toBe(true);
+      expect(prompts.length).toBeGreaterThan(0);
+    });
+
+    it('should only include tools with prompt property', () => {
+      const prompts = getPromptDefinitions();
+
+      prompts.forEach(prompt => {
+        expect(prompt).toHaveProperty('name');
+        expect(prompt).toHaveProperty('description');
+        expect(prompt).toHaveProperty('arguments');
+      });
+    });
+
+    it('should include ask-gemini prompt', () => {
+      const prompts = getPromptDefinitions();
+      const askGeminiPrompt = prompts.find(p => p.name === 'ask-gemini');
+
+      expect(askGeminiPrompt).toBeDefined();
+      expect(askGeminiPrompt?.description).toBeTruthy();
+    });
+
+    it('should include brainstorm prompt', () => {
+      const prompts = getPromptDefinitions();
+      const brainstormPrompt = prompts.find(p => p.name === 'brainstorm');
+
+      expect(brainstormPrompt).toBeDefined();
+    });
+  });
+
+  describe('Tool Schema Validation', () => {
+    it('ask-gemini should have required prompt parameter', () => {
+      const tools = getToolDefinitions();
+      const askGeminiTool = tools.find(t => t.name === 'ask-gemini');
+
+      expect(askGeminiTool?.inputSchema.properties).toHaveProperty('prompt');
+      expect(askGeminiTool?.inputSchema.required).toContain('prompt');
+    });
+
+    it('ask-gemini should have optional parameters', () => {
+      const tools = getToolDefinitions();
+      const askGeminiTool = tools.find(t => t.name === 'ask-gemini');
+
+      const properties = askGeminiTool?.inputSchema.properties;
+      expect(properties).toHaveProperty('model');
+      expect(properties).toHaveProperty('sandbox');
+      expect(properties).toHaveProperty('changeMode');
+      expect(properties).toHaveProperty('yolo');
+      expect(properties).toHaveProperty('approvalMode');
+    });
+
+    it('brainstorm should have methodology parameter', () => {
+      const tools = getToolDefinitions();
+      const brainstormTool = tools.find(t => t.name === 'brainstorm');
+
+      expect(brainstormTool?.inputSchema.properties).toHaveProperty('methodology');
+    });
+
+    it('fetch-chunk should have required cacheKey and chunkIndex', () => {
+      const tools = getToolDefinitions();
+      const fetchChunkTool = tools.find(t => t.name === 'fetch-chunk');
+
+      expect(fetchChunkTool?.inputSchema.properties).toHaveProperty('cacheKey');
+      expect(fetchChunkTool?.inputSchema.properties).toHaveProperty('chunkIndex');
+      expect(fetchChunkTool?.inputSchema.required).toContain('cacheKey');
+      expect(fetchChunkTool?.inputSchema.required).toContain('chunkIndex');
+    });
+  });
+
+  describe('Tool Categories', () => {
+    it('should categorize tools correctly', () => {
+      const askGemini = toolRegistry.find(t => t.name === 'ask-gemini');
+      const brainstorm = toolRegistry.find(t => t.name === 'brainstorm');
+      const ping = toolRegistry.find(t => t.name === 'ping');
+      const fetchChunk = toolRegistry.find(t => t.name === 'fetch-chunk');
+
+      expect(askGemini?.category).toBe('gemini');
+      expect(brainstorm?.category).toBe('gemini');
+      expect(ping?.category).toBe('simple');
+      expect(fetchChunk?.category).toBe('utility');
+    });
+  });
+});
diff --git a/src/__tests__/utils/test-helpers.ts b/src/__tests__/utils/test-helpers.ts
new file mode 100644
index 0000000..3f3bd29
--- /dev/null
+++ b/src/__tests__/utils/test-helpers.ts
@@ -0,0 +1,51 @@
+import { vi } from 'vitest';
+import { EventEmitter } from 'node:events';
+
+/**
+ * Creates a mock child process for testing command execution
+ */
+export function createMockProcess() {
+  const mockProcess = new EventEmitter() as any;
+  mockProcess.stdout = new EventEmitter();
+  mockProcess.stderr = new EventEmitter();
+  mockProcess.stdout.on = vi.fn((event, handler) => {
+    if (event === 'data') mockProcess.stdout['data'] = handler;
+  });
+  mockProcess.stderr.on = vi.fn((event, handler) => {
+    if (event === 'data') mockProcess.stderr['data'] = handler;
+  });
+  return mockProcess;
+}
+
+/**
+ * Simulates successful process execution
+ */
+export function simulateProcessSuccess(mockProcess: any, output: string, delay = 10) {
+  setTimeout(() => {
+    if (mockProcess.stdout['data']) {
+      mockProcess.stdout['data'](output);
+    }
+    mockProcess.emit('close', 0);
+  }, delay);
+}
+
+/**
+ * Simulates process failure
+ */
+export function simulateProcessFailure(mockProcess: any, errorOutput: string, exitCode = 1, delay = 10) {
+  setTimeout(() => {
+    if (mockProcess.stderr['data']) {
+      mockProcess.stderr['data'](errorOutput);
+    }
+    mockProcess.emit('close', exitCode);
+  }, delay);
+}
+
+/**
+ * Simulates process error
+ */
+export function simulateProcessError(mockProcess: any, error: Error, delay = 10) {
+  setTimeout(() => {
+    mockProcess.emit('error', error);
+  }, delay);
+}
diff --git a/src/constants.ts b/src/constants.ts
index 184cac2..3830fd0 100644
--- a/src/constants.ts
+++ b/src/constants.ts
@@ -70,12 +70,28 @@ export const CLI = {
     SANDBOX: "-s",
     PROMPT: "-p",
     HELP: "-help",
+    // Phase 1: Critical flags
+    YOLO: "-y",
+    APPROVAL_MODE: "--approval-mode",
+    OUTPUT_FORMAT: "-o",
+    INCLUDE_DIRECTORIES: "--include-directories",
+    DEBUG: "-d",
+    // Phase 2: Enhanced features
+    PROMPT_INTERACTIVE: "-i",
+    EXTENSIONS: "-e",
+    RESUME: "-r",
   },
   // Default values
   DEFAULTS: {
     MODEL: "default", // Fallback model used when no specific model is provided
     BOOLEAN_TRUE: "true",
     BOOLEAN_FALSE: "false",
+    APPROVAL_MODE_DEFAULT: "default",
+    APPROVAL_MODE_AUTO_EDIT: "auto_edit",
+    APPROVAL_MODE_YOLO: "yolo",
+    OUTPUT_FORMAT_TEXT: "text",
+    OUTPUT_FORMAT_JSON: "json",
+    OUTPUT_FORMAT_STREAM_JSON: "stream-json",
   },
 } as const;
 
@@ -89,14 +105,26 @@ export interface ToolArguments {
   chunkIndex?: number | string; // Which chunk to return (1-based)
   chunkCacheKey?: string; // Optional cache key for continuation
   message?: string; // For Ping tool -- Un-used.
-  
-  // --> new tool
+
+  // Phase 1: Critical flags
+  yolo?: boolean | string; // Auto-accept all actions (YOLO mode)
+  approvalMode?: string; // Approval mode: default, auto_edit, yolo
+  outputFormat?: string; // Output format: text, json, stream-json
+  includeDirectories?: string | string[]; // Additional directories to include
+  debug?: boolean | string; // Enable debug mode
+
+  // Phase 2: Enhanced features
+  promptInteractive?: string; // Execute prompt and continue interactively
+  extensions?: string | string[]; // Extensions to use
+  resume?: string; // Resume previous session
+
+  // Brainstorm tool
   methodology?: string; // Brainstorming framework to use
   domain?: string; // Domain context for specialized brainstorming
   constraints?: string; // Known limitations or requirements
   existingContext?: string; // Background information to build upon
   ideaCount?: number; // Target number of ideas to generate
   includeAnalysis?: boolean; // Include feasibility and impact analysis
-  
-  [key: string]: string | boolean | number | undefined; // Allow additional properties
+
+  [key: string]: string | boolean | number | string[] | undefined; // Allow additional properties
 }
\ No newline at end of file
diff --git a/src/index.ts b/src/index.ts
index 46c6118..88879b9 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -36,7 +36,6 @@ const server = new Server(
       tools: {},
       prompts: {},
       notifications: {},
-      logging: {},
     },
   },
 );
diff --git a/src/tools/ask-gemini.tool.ts b/src/tools/ask-gemini.tool.ts
index bc76b3a..b9117ed 100644
--- a/src/tools/ask-gemini.tool.ts
+++ b/src/tools/ask-gemini.tool.ts
@@ -13,18 +13,34 @@ const askGeminiArgsSchema = z.object({
   changeMode: z.boolean().default(false).describe("Enable structured change mode - formats prompts to prevent tool errors and returns structured edit suggestions that Claude can apply directly"),
   chunkIndex: z.union([z.number(), z.string()]).optional().describe("Which chunk to return (1-based)"),
   chunkCacheKey: z.string().optional().describe("Optional cache key for continuation"),
+
+  // Phase 1: Critical flags
+  yolo: z.boolean().default(false).describe("Auto-accept all actions (YOLO mode). Automatically approves all confirmations without prompting. Use with caution in automated workflows."),
+  approvalMode: z.enum(["default", "auto_edit", "yolo"]).optional().describe("Set approval mode: 'default' (prompt for approval), 'auto_edit' (auto-approve edit tools only), 'yolo' (auto-approve all tools). Overrides yolo flag if both are set."),
+  outputFormat: z.enum(["text", "json", "stream-json"]).optional().describe("Output format: 'text' (default human-readable), 'json' (structured JSON), 'stream-json' (streaming JSON for real-time processing)"),
+  includeDirectories: z.union([z.string(), z.array(z.string())]).optional().describe("Additional directories to include in workspace (comma-separated string or array). Example: 'src,tests' or ['src', 'tests']"),
+  debug: z.boolean().default(false).describe("Enable debug mode for verbose logging and troubleshooting"),
+
+  // Phase 2: Enhanced features (for future implementation)
+  promptInteractive: z.string().optional().describe("Execute the provided prompt and continue in interactive mode"),
+  extensions: z.union([z.string(), z.array(z.string())]).optional().describe("Specific extensions to use (comma-separated or array). If not provided, all extensions are used."),
+  resume: z.string().optional().describe("Resume a previous session. Use 'latest' for most recent or session index number"),
 });
 
 export const askGeminiTool: UnifiedTool = {
   name: "ask-gemini",
-  description: "model selection [-m], sandbox [-s], and changeMode:boolean for providing edits",
+  description: "Ask Google Gemini with full CLI support: model selection [-m], sandbox [-s], YOLO mode [-y], approval modes, output formats, and more",
   zodSchema: askGeminiArgsSchema,
   prompt: {
-    description: "Execute 'gemini -p <prompt>' to get Gemini AI's response. Supports enhanced change mode for structured edit suggestions.",
+    description: "Execute Gemini CLI with advanced options. Supports file analysis (@syntax), YOLO mode, different approval levels, output formats (text/json), debug mode, and structured change mode for edit suggestions.",
   },
   category: 'gemini',
   execute: async (args, onProgress) => {
-    const { prompt, model, sandbox, changeMode, chunkIndex, chunkCacheKey } = args; if (!prompt?.trim()) { throw new Error(ERROR_MESSAGES.NO_PROMPT_PROVIDED); }
+    const {
+      prompt, model, sandbox, changeMode, chunkIndex, chunkCacheKey,
+      yolo, approvalMode, outputFormat, includeDirectories, debug,
+      promptInteractive, extensions, resume
+    } = args; if (!prompt?.trim()) { throw new Error(ERROR_MESSAGES.NO_PROMPT_PROVIDED); }
   
     if (changeMode && chunkIndex && chunkCacheKey) {
       return processChangeModeOutput(
@@ -37,9 +53,19 @@ export const askGeminiTool: UnifiedTool = {
     
     const result = await executeGeminiCLI(
       prompt as string,
-      model as string | undefined,
-      !!sandbox,
-      !!changeMode,
+      {
+        model: model as string | undefined,
+        sandbox: !!sandbox,
+        changeMode: !!changeMode,
+        yolo: !!yolo,
+        approvalMode: approvalMode as string | undefined,
+        outputFormat: outputFormat as string | undefined,
+        includeDirectories: includeDirectories,
+        debug: !!debug,
+        promptInteractive: promptInteractive as string | undefined,
+        extensions: extensions,
+        resume: resume as string | undefined,
+      },
       onProgress
     );
     
diff --git a/src/tools/brainstorm.tool.ts b/src/tools/brainstorm.tool.ts
index 0970ade..58717a1 100644
--- a/src/tools/brainstorm.tool.ts
+++ b/src/tools/brainstorm.tool.ts
@@ -166,6 +166,14 @@ export const brainstormTool: UnifiedTool = {
     onProgress?.(`Generating ${ideaCount} ideas via ${methodology} methodology...`);
     
     // Execute with Gemini
-    return await executeGeminiCLI(enhancedPrompt, model as string | undefined, false, false, onProgress);
+    return await executeGeminiCLI(
+      enhancedPrompt,
+      {
+        model: model as string | undefined,
+        sandbox: false,
+        changeMode: false,
+      },
+      onProgress
+    );
   }
 };
\ No newline at end of file
diff --git a/src/utils/commandExecutor.ts b/src/utils/commandExecutor.ts
index b9b6f1b..8231735 100644
--- a/src/utils/commandExecutor.ts
+++ b/src/utils/commandExecutor.ts
@@ -16,31 +16,32 @@ export async function executeCommand(
       stdio: ["ignore", "pipe", "pipe"],
     });
 
-    let stdout = "";
-    let stderr = "";
+    // Use array buffers for O(n) performance instead of O(n²) string concatenation
+    const stdoutChunks: string[] = [];
+    const stderrChunks: string[] = [];
     let isResolved = false;
-    let lastReportedLength = 0;
-    
+
     childProcess.stdout.on("data", (data) => {
-      stdout += data.toString();
-      
-      // Report new content if callback provided
-      if (onProgress && stdout.length > lastReportedLength) {
-        const newContent = stdout.substring(lastReportedLength);
-        lastReportedLength = stdout.length;
-        onProgress(newContent);
+      const chunk = data.toString();
+      stdoutChunks.push(chunk);
+
+      // Report immediately if callback provided (no substring calculation needed)
+      if (onProgress) {
+        onProgress(chunk);
       }
     });
 
 
     // CLI level errors
     childProcess.stderr.on("data", (data) => {
-      stderr += data.toString();
+      const chunk = data.toString();
+      stderrChunks.push(chunk);
       // find RESOURCE_EXHAUSTED when gemini-2.5-pro quota is exceeded
-      if (stderr.includes("RESOURCE_EXHAUSTED")) {
-        const modelMatch = stderr.match(/Quota exceeded for quota metric '([^']+)'/);
-        const statusMatch = stderr.match(/status["\s]*[:=]\s*(\d+)/);
-        const reasonMatch = stderr.match(/"reason":\s*"([^"]+)"/);
+      if (chunk.includes("RESOURCE_EXHAUSTED")) {
+        const stderrSoFar = stderrChunks.join('');
+        const modelMatch = stderrSoFar.match(/Quota exceeded for quota metric '([^']+)'/);
+        const statusMatch = stderrSoFar.match(/status["\s]*[:=]\s*(\d+)/);
+        const reasonMatch = stderrSoFar.match(/"reason":\s*"([^"]+)"/);
         const model = modelMatch ? modelMatch[1] : "Unknown Model";
         const status = statusMatch ? statusMatch[1] : "429";
         const reason = reasonMatch ? reasonMatch[1] : "rateLimitExceeded";
@@ -68,6 +69,10 @@ export async function executeCommand(
     childProcess.on("close", (code) => {
       if (!isResolved) {
         isResolved = true;
+        // Join array buffers efficiently
+        const stdout = stdoutChunks.join('');
+        const stderr = stderrChunks.join('');
+
         if (code === 0) {
           Logger.commandComplete(startTime, code, stdout.length);
           resolve(stdout.trim());
diff --git a/src/utils/geminiExecutor.ts b/src/utils/geminiExecutor.ts
index f7e79d3..7cb0085 100644
--- a/src/utils/geminiExecutor.ts
+++ b/src/utils/geminiExecutor.ts
@@ -1,9 +1,9 @@
 import { executeCommand } from './commandExecutor.js';
 import { Logger } from './logger.js';
-import { 
-  ERROR_MESSAGES, 
-  STATUS_MESSAGES, 
-  MODELS, 
+import {
+  ERROR_MESSAGES,
+  STATUS_MESSAGES,
+  MODELS,
   CLI
 } from '../constants.js';
 
@@ -11,19 +11,120 @@ import { parseChangeModeOutput, validateChangeModeEdits } from './changeModePars
 import { formatChangeModeResponse, summarizeChangeModeEdits } from './changeModeTranslator.js';
 import { chunkChangeModeEdits } from './changeModeChunker.js';
 import { cacheChunks, getChunks } from './chunkCache.js';
+import { generateCacheKey, getCachedResponse, cacheResponse } from './responseCache.js';
+
+export interface GeminiCLIOptions {
+  model?: string;
+  sandbox?: boolean;
+  changeMode?: boolean;
+  yolo?: boolean;
+  approvalMode?: string;
+  outputFormat?: string;
+  includeDirectories?: string | string[];
+  debug?: boolean;
+  promptInteractive?: string;
+  extensions?: string | string[];
+  resume?: string;
+}
+
+/**
+ * Helper function to build Gemini CLI arguments from options
+ * Eliminates code duplication between main execution and fallback
+ */
+function buildGeminiArgs(opts: GeminiCLIOptions, prompt: string, forceModel?: string): string[] {
+  const args: string[] = [];
+  const model = forceModel || opts.model;
+
+  // Model selection
+  if (model) {
+    args.push(CLI.FLAGS.MODEL, model);
+  }
+
+  // Boolean flags
+  if (opts.sandbox) {
+    args.push(CLI.FLAGS.SANDBOX);
+  }
+  if (opts.yolo) {
+    args.push(CLI.FLAGS.YOLO);
+  }
+  if (opts.debug) {
+    args.push(CLI.FLAGS.DEBUG);
+  }
+
+  // Approval mode (overrides yolo if both are set)
+  if (opts.approvalMode) {
+    args.push(CLI.FLAGS.APPROVAL_MODE, opts.approvalMode);
+  }
+
+  // Output format
+  if (opts.outputFormat) {
+    args.push(CLI.FLAGS.OUTPUT_FORMAT, opts.outputFormat);
+  }
+
+  // Include directories (array or comma-separated string)
+  if (opts.includeDirectories) {
+    const dirs = Array.isArray(opts.includeDirectories)
+      ? opts.includeDirectories.join(',')
+      : opts.includeDirectories;
+    args.push(CLI.FLAGS.INCLUDE_DIRECTORIES, dirs);
+  }
+
+  // Extensions (array or comma-separated string)
+  if (opts.extensions) {
+    const exts = Array.isArray(opts.extensions)
+      ? opts.extensions.join(',')
+      : opts.extensions;
+    args.push(CLI.FLAGS.EXTENSIONS, exts);
+  }
+
+  // Resume session
+  if (opts.resume) {
+    args.push(CLI.FLAGS.RESUME, opts.resume);
+  }
+
+  // Prompt interactive
+  if (opts.promptInteractive) {
+    args.push(CLI.FLAGS.PROMPT_INTERACTIVE, opts.promptInteractive);
+  }
+
+  // Ensure @ symbols work cross-platform by wrapping in quotes if needed
+  const finalPrompt = prompt.includes('@') && !prompt.startsWith('"')
+    ? `"${prompt}"`
+    : prompt;
+
+  args.push(CLI.FLAGS.PROMPT, finalPrompt);
+
+  return args;
+}
 
 export async function executeGeminiCLI(
   prompt: string,
-  model?: string,
-  sandbox?: boolean,
-  changeMode?: boolean,
+  options: GeminiCLIOptions | string,
   onProgress?: (newOutput: string) => void
 ): Promise<string> {
+  // Handle backward compatibility - if options is a string, it's the old 'model' parameter
+  let opts: GeminiCLIOptions;
+  if (typeof options === 'string') {
+    opts = { model: options };
+  } else {
+    opts = options || {};
+  }
+
+  // Check cache first for non-changeMode requests (changeMode needs fresh responses)
+  if (!opts.changeMode) {
+    const cacheKey = generateCacheKey(prompt, opts);
+    const cached = getCachedResponse(cacheKey);
+    if (cached) {
+      Logger.debug('Returning cached response');
+      return cached;
+    }
+  }
+
   let prompt_processed = prompt;
-  
-  if (changeMode) {
+
+  if (opts.changeMode) {
     prompt_processed = prompt.replace(/file:(\S+)/g, '@$1');
-    
+
     const changeModeInstructions = `
 [CHANGEMODE INSTRUCTIONS]
 You are generating code modifications that will be processed by an automated system. The output format is critical because it enables programmatic application of changes without human intervention.
@@ -86,41 +187,40 @@ ${prompt_processed}
 `;
     prompt_processed = changeModeInstructions;
   }
-  
-  const args = [];
-  if (model) { args.push(CLI.FLAGS.MODEL, model); }
-  if (sandbox) { args.push(CLI.FLAGS.SANDBOX); }
-  
-  // Ensure @ symbols work cross-platform by wrapping in quotes if needed
-  const finalPrompt = prompt_processed.includes('@') && !prompt_processed.startsWith('"') 
-    ? `"${prompt_processed}"` 
-    : prompt_processed;
-    
-  args.push(CLI.FLAGS.PROMPT, finalPrompt);
-  
+
+  // Use helper function to build args (eliminates code duplication)
+  const args = buildGeminiArgs(opts, prompt_processed);
+
   try {
-    return await executeCommand(CLI.COMMANDS.GEMINI, args, onProgress);
+    const result = await executeCommand(CLI.COMMANDS.GEMINI, args, onProgress);
+
+    // Cache successful non-changeMode responses
+    if (!opts.changeMode) {
+      const cacheKey = generateCacheKey(prompt, opts);
+      cacheResponse(cacheKey, result);
+    }
+
+    return result;
   } catch (error) {
     const errorMessage = error instanceof Error ? error.message : String(error);
-    if (errorMessage.includes(ERROR_MESSAGES.QUOTA_EXCEEDED) && model !== MODELS.FLASH) {
+    if (errorMessage.includes(ERROR_MESSAGES.QUOTA_EXCEEDED) && opts.model !== MODELS.FLASH) {
       Logger.warn(`${ERROR_MESSAGES.QUOTA_EXCEEDED}. Falling back to ${MODELS.FLASH}.`);
       await sendStatusMessage(STATUS_MESSAGES.FLASH_RETRY);
-      const fallbackArgs = [];
-      fallbackArgs.push(CLI.FLAGS.MODEL, MODELS.FLASH);
-      if (sandbox) {
-        fallbackArgs.push(CLI.FLAGS.SANDBOX);
-      }
-      
-      // Same @ symbol handling for fallback
-      const fallbackPrompt = prompt_processed.includes('@') && !prompt_processed.startsWith('"') 
-        ? `"${prompt_processed}"` 
-        : prompt_processed;
-        
-      fallbackArgs.push(CLI.FLAGS.PROMPT, fallbackPrompt);
+
+      // Use helper function with Flash model override (eliminates code duplication)
+      const fallbackArgs = buildGeminiArgs(opts, prompt_processed, MODELS.FLASH);
+
       try {
         const result = await executeCommand(CLI.COMMANDS.GEMINI, fallbackArgs, onProgress);
         Logger.warn(`Successfully executed with ${MODELS.FLASH} fallback.`);
         await sendStatusMessage(STATUS_MESSAGES.FLASH_SUCCESS);
+
+        // Cache successful fallback response (non-changeMode only)
+        if (!opts.changeMode) {
+          const cacheKey = generateCacheKey(prompt, opts);
+          cacheResponse(cacheKey, result);
+        }
+
         return result;
       } catch (fallbackError) {
         const fallbackErrorMessage = fallbackError instanceof Error ? fallbackError.message : String(fallbackError);
diff --git a/src/utils/responseCache.ts b/src/utils/responseCache.ts
new file mode 100644
index 0000000..e36282c
--- /dev/null
+++ b/src/utils/responseCache.ts
@@ -0,0 +1,86 @@
+import { LRUCache } from 'lru-cache';
+import { createHash } from 'crypto';
+import { Logger } from './logger.js';
+import { GeminiCLIOptions } from './geminiExecutor.js';
+
+/**
+ * LRU Cache for Gemini API responses
+ * Caches responses to identical prompts with identical options
+ *
+ * Benefits:
+ * - Near-instant responses for repeated queries
+ * - Reduces API quota consumption
+ * - 30-minute TTL ensures fresh data
+ * - 10MB max size prevents memory bloat
+ */
+const responseCache = new LRUCache<string, string>({
+  max: 100,  // Cache up to 100 recent responses
+  ttl: 1000 * 60 * 30,  // 30 minutes
+  maxSize: 10 * 1024 * 1024,  // 10MB max cache size
+  sizeCalculation: (value) => value.length,
+  dispose: (value, key) => {
+    Logger.debug(`Cache evicted: ${key.substring(0, 16)}...`);
+  }
+});
+
+/**
+ * Generate a cache key from prompt and options
+ */
+export function generateCacheKey(prompt: string, options: GeminiCLIOptions): string {
+  // Create deterministic hash of prompt + options
+  const cacheInput = JSON.stringify({
+    prompt,
+    model: options.model,
+    sandbox: options.sandbox,
+    changeMode: options.changeMode,
+    yolo: options.yolo,
+    approvalMode: options.approvalMode,
+    outputFormat: options.outputFormat,
+    includeDirectories: options.includeDirectories,
+    debug: options.debug,
+    promptInteractive: options.promptInteractive,
+    extensions: options.extensions,
+    resume: options.resume
+  });
+
+  return createHash('sha256').update(cacheInput).digest('hex');
+}
+
+/**
+ * Get cached response if available
+ */
+export function getCachedResponse(cacheKey: string): string | undefined {
+  const cached = responseCache.get(cacheKey);
+  if (cached) {
+    Logger.debug(`Cache hit: ${cacheKey.substring(0, 16)}...`);
+  }
+  return cached;
+}
+
+/**
+ * Cache a response
+ */
+export function cacheResponse(cacheKey: string, response: string): void {
+  responseCache.set(cacheKey, response);
+  Logger.debug(`Cached response: ${cacheKey.substring(0, 16)}... (${response.length} bytes)`);
+}
+
+/**
+ * Clear the entire cache
+ */
+export function clearCache(): void {
+  responseCache.clear();
+  Logger.debug('Response cache cleared');
+}
+
+/**
+ * Get cache statistics
+ */
+export function getCacheStats() {
+  return {
+    size: responseCache.size,
+    maxSize: responseCache.max,
+    calculatedSize: responseCache.calculatedSize,
+    maxCalculatedSize: responseCache.maxSize
+  };
+}
diff --git a/vitest.config.ts b/vitest.config.ts
new file mode 100644
index 0000000..274518a
--- /dev/null
+++ b/vitest.config.ts
@@ -0,0 +1,22 @@
+import { defineConfig } from 'vitest/config';
+
+export default defineConfig({
+  test: {
+    globals: true,
+    environment: 'node',
+    coverage: {
+      provider: 'v8',
+      reporter: ['text', 'json', 'html'],
+      exclude: [
+        'node_modules/**',
+        'dist/**',
+        '**/*.d.ts',
+        '**/*.test.ts',
+        '**/*.spec.ts',
+      ],
+    },
+    mockReset: true,
+    clearMocks: true,
+    restoreMocks: true,
+  },
+});