diff --git a/.all-contributorsrc b/.all-contributorsrc
index 72ae3b71..933a828e 100644
--- a/.all-contributorsrc
+++ b/.all-contributorsrc
@@ -437,7 +437,28 @@
       "name": "Mihamina Rakotomandimby",
       "avatar_url": "https://avatars.githubusercontent.com/u/488088?v=4",
       "profile": "https://mihamina.rktmb.org",
-      "contributions": ["doc"]
+      "contributions": ["doc", "code"]
+    },
+    {
+      "login": "AjmalShajahan",
+      "name": "Ajmal S",
+      "avatar_url": "https://avatars.githubusercontent.com/u/23806715?v=4",
+      "profile": "http://ajmalshajahan.me",
+      "contributions": ["code"]
+    },
+    {
+      "login": "samiulsami",
+      "name": "Samiul Islam",
+      "avatar_url": "https://avatars.githubusercontent.com/u/33352407?v=4",
+      "profile": "https://github.com/samiulsami",
+      "contributions": ["code"]
+    },
+    {
+      "login": "ruicsh",
+      "name": "Rui Costa",
+      "avatar_url": "https://avatars.githubusercontent.com/u/8294038?v=4",
+      "profile": "https://ruicsh.github.io",
+      "contributions": ["code"]
     }
   ],
   "contributorsPerLine": 7,
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e722714f..9ce3f370 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -64,8 +64,4 @@ jobs:
           luarocksVersion: "3.12.2"
 
       - name: run test
-        shell: bash
-        run: |
-          luarocks install luacheck
-          luarocks install vusted
-          vusted ./test
+        run: make test
diff --git a/.gitignore b/.gitignore
index 94e6f763..fc3fe2ac 100644
--- a/.gitignore
+++ b/.gitignore
@@ -165,3 +165,5 @@ cython_debug/
 
 # (neo)vim helptags
 /doc/tags
+
+.dependencies/
diff --git a/.luarc.json b/.luarc.json
index b97a9f11..c4cebd58 100644
--- a/.luarc.json
+++ b/.luarc.json
@@ -1,4 +1,14 @@
 {
-  "diagnostics.globals": ["describe", "it"],
+  "runtime.version": "LuaJIT",
+  "diagnostics.globals": [
+    "describe",
+    "it",
+    "pending",
+    "before_each",
+    "after_each",
+    "clear",
+    "assert",
+    "print"
+  ],
   "diagnostics.disable": ["redefined-local"]
 }
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1df5c92e..4e5b2c33 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,49 @@
 # Changelog
 
+## [4.5.0](https://github.com/CopilotC-Nvim/CopilotChat.nvim/compare/v4.4.1...v4.5.0) (2025-08-27)
+
+
+### ⚠ BREAKING CHANGES
+
+* **select:** remove selection API in favor of resources
+* **prompts:** callback receives the full response object instead of just content.
+
+### Features
+
+* **config:** add back selection source config option ([#1360](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1360)) ([c37ec3c](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/c37ec3cbdb2c29be73d7d0c48057d64306aa185f))
+* **docs:** add selection source to function table ([#1358](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1358)) ([c7d8547](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/c7d85478f775a65ca777cb9b2f685911cbcd8def))
+* **functions:** add configuration parameter to stop on tool failure ([#1364](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1364)) ([8d8f1e7](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/8d8f1e7ea594b2db3368e1fa62dd7d0d128e8860))
+* **functions:** add scope=selection to diagnostics ([#1351](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1351)) ([7b4a56b](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/7b4a56b29ed926b680ea936bd29fc8568b909d97))
+* **functions:** use cwd for file and grep commands ([#1373](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1373)) ([72216c0](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/72216c06fa2ce82406c3406d898a83c02db412a7)), closes [#1108](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1108)
+* **prompts:** add support for providing system prompt as function ([#1318](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1318)) ([33e6ffc](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/33e6ffc63b77b0340731f2b50bd962045adf9366))
+* **prompts:** support buffer replacement in commit messages ([#1370](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1370)) ([afafec5](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/afafec51d2657cdde4fa839bac9cc203037ff60b))
+* **ui:** add auto_fold option for chat messages ([#1354](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1354)) ([80a0994](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/80a0994f01096705e0c24dd7ed09032594689e01)), closes [#1300](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1300)
+* **ui:** improve auto folding logic in chat window ([#1356](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1356)) ([a7679e1](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/a7679e118af8038046b2fc4c841406db7fe71216))
+
+
+### Bug Fixes
+
+* **completion.lua:** check if window is valid before calling get_cursor ([#1359](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1359)) ([fdac67a](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/fdac67ab62085436b60003f420ae45f104bdf935))
+* **completion:** require tool uri for input completion ([#1328](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1328)) ([76cc416](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/76cc41653d63cfdb653f584624b4bf5e721f9514))
+* **config:** correct system_prompt type and callback usage ([#1325](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1325)) ([f99f1cd](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/f99f1cdef151ac1c950850cdcc0dbeefad00603c))
+* **makefile:** handle MSYS_NT as a valid Windows environment ([#1347](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1347)) ([9769bf9](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/9769bf9a1d215cf0dc22874712d5dcda53a075ee))
+* **prompt:** recursive system prompt expansion ([#1324](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1324)) ([26f7b4f](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/26f7b4f157ec75b168c05dc826b5fa3106cfc351)), closes [#1323](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1323)
+* **select:** move config inside of marks function to prevent import loop ([#1361](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1361)) ([19a38dd](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/19a38dd34e1b61c49349552598e43b2559be2fc7))
+* **test:** run tests automatically in test script ([#1334](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1334)) ([c5057d3](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/c5057d3bb6d87e9b117b4f37162409d4c2c74e31))
+* **utils:** always exit insert mode in return_to_normal_mode ([#1313](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1313)) ([957e0a8](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/957e0a88c7d7df706380e09412c0b3f24af534ad)), closes [#1307](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1307)
+* **utils:** avoid vim.filetype.match in fast event ([#1344](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1344)) ([7993e6d](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/7993e6d2a97cb851b8b3a4087005cfaf8427dbf3))
+
+
+### Miscellaneous Chores
+
+* mark next release as 4.5.0 ([#1315](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1315)) ([d12f6df](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/d12f6dff0e1641f933f9941b843d094bf505a82e))
+
+
+### Code Refactoring
+
+* **prompts:** support template substitution in system_prompt ([#1312](https://github.com/CopilotC-Nvim/CopilotChat.nvim/issues/1312)) ([081d4c2](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/081d4c20242140bb185ebee142a65454ad375f7d))
+* **select:** remove selection API in favor of resources ([a2429ed](https://github.com/CopilotC-Nvim/CopilotChat.nvim/commit/a2429ed44438f694f1fca60429a7984022d4a9f0))
+
 ## [4.4.1](https://github.com/CopilotC-Nvim/CopilotChat.nvim/compare/v4.4.0...v4.4.1) (2025-08-12)
 
 
diff --git a/Makefile b/Makefile
index c5d53c52..ebfe5768 100644
--- a/Makefile
+++ b/Makefile
@@ -10,6 +10,9 @@ else ifeq ($(UNAME), Darwin)
 else ifeq ($(UNAME), Windows_NT)
     OS := windows
     EXT := dll
+else ifneq ($(findstring MSYS_NT,$(UNAME)),)
+    OS := windows
+    EXT := dll
 else
     $(error Unsupported operating system: $(UNAME))
 endif
@@ -19,28 +22,12 @@ BUILD_DIR := build
 
 .PHONY: help install-cli install-pre-commit install test tiktoken clean
 
-help:
-	@echo "Available commands:"
-	@echo "  install-cli       - Install Lua and Luarocks using Homebrew"
-	@echo "  install-pre-commit - Install pre-commit using pip"
-	@echo "  install           - Install vusted using Luarocks"
-	@echo "  test              - Run tests using vusted"
-	@echo "  tiktoken          - Download tiktoken_core library"
-	@echo "  clean             - Remove build directory"
-
-install-cli:
-	brew install luarocks
-	brew install lua
-
 install-pre-commit:
 	pip install pre-commit
 	pre-commit install
 
-install:
-	luarocks install vusted
-
 test:
-	vusted test
+	nvim --headless --clean -u ./scripts/test.lua
 
 all: luajit
 
diff --git a/README.md b/README.md
index f4111a0f..07f43d6c 100644
--- a/README.md
+++ b/README.md
@@ -95,7 +95,6 @@ EOF
 - **Sticky Prompts** (`> <text>`) - Persist context across single chat session
 - **Models** (`$<model>`) - Specify which AI model to use for the chat
 - **Prompts** (`/PromptName`) - Use predefined prompt templates for common tasks
-- **Selection** - Automatically includes current user selection in prompts
 
 ## Examples
 
@@ -180,6 +179,7 @@ All predefined functions belong to the `copilot` group.
 | `grep`        | Searches for a pattern across files in workspace | `#grep:TODO`           |
 | `quickfix`    | Includes content of files in quickfix list       | `#quickfix`            |
 | `register`    | Provides access to specified Vim register        | `#register:+`          |
+| `selection`   | Includes the current visual selection            | `#selection`           |
 | `url`         | Fetches content from a specified URL             | `#url:https://...`     |
 
 ## Predefined Prompts
@@ -228,12 +228,13 @@ Most users only need to configure a few options:
   },
 
   headers = {
-    user = '👤 You: ',
-    assistant = '🤖 Copilot: ',
-    tool = '🔧 Tool: ',
+    user = '👤 You',
+    assistant = '🤖 Copilot',
+    tool = '🔧 Tool',
   },
+
   separator = '━━',
-  show_folds = false, -- Disable folding for cleaner look
+  auto_fold = true, -- Automatically folds non-assistant messages
 }
 ```
 
@@ -265,6 +266,7 @@ Types of copilot highlights:
 
 - `CopilotChatHeader` - Header highlight in chat buffer
 - `CopilotChatSeparator` - Separator highlight in chat buffer
+- `CopilotChatSelection` - Selection highlight in source buffer
 - `CopilotChatStatus` - Status and spinner in chat buffer
 - `CopilotChatHelp` - Help text in chat buffer
 - `CopilotChatResource` - Resource highlight in chat buffer (e.g. `#file`, `#gitdiff`)
@@ -272,7 +274,6 @@ Types of copilot highlights:
 - `CopilotChatPrompt` - Prompt highlight in chat buffer (e.g. `/Explain`, `/Review`)
 - `CopilotChatModel` - Model highlight in chat buffer (e.g. `$gpt-4.1`)
 - `CopilotChatUri` - URI highlight in chat buffer (e.g. `##https://...`)
-- `CopilotChatSelection` - Selection highlight in source buffer
 - `CopilotChatAnnotation` - Annotation highlight in chat buffer (file headers, tool call headers, tool call body)
 
 ## Prompts
@@ -292,7 +293,7 @@ Define your own prompts in the configuration:
       system_prompt = 'You are fascinated by pirates, so please respond in pirate speak.',
     },
     NiceInstructions = {
-      system_prompt = 'You are a nice coding tutor, so please respond in a friendly and helpful manner.' .. require('CopilotChat.config.prompts').COPILOT_BASE.system_prompt,
+      system_prompt = 'You are a nice coding tutor, so please respond in a friendly and helpful manner.',
     }
   }
 }
@@ -333,27 +334,6 @@ Define your own functions in the configuration with input handling and schema:
 }
 ```
 
-## Selections
-
-Control what content is automatically included:
-
-```lua
-{
-  -- Use visual selection, fallback to current line
-  selection = function(source)
-    return require('CopilotChat.select').visual(source) or
-           require('CopilotChat.select').line(source)
-  end,
-}
-```
-
-**Available selections:**
-
-- `require('CopilotChat.select').visual` - Current visual selection
-- `require('CopilotChat.select').buffer` - Entire buffer content
-- `require('CopilotChat.select').line` - Current line content
-- `require('CopilotChat.select').unnamed` - Unnamed register (last deleted/changed/yanked)
-
 ## Providers
 
 Add custom AI providers:
@@ -429,10 +409,6 @@ chat.stop()                   -- Stop current output
 chat.get_source()             -- Get the current source buffer and window
 chat.set_source(winnr)        -- Set the source window
 
--- Selection Management
-chat.get_selection()                                   -- Get the current selection
-chat.set_selection(bufnr, start_line, end_line, clear) -- Set or clear selection
-
 -- Prompt & Model Management
 chat.select_prompt(config)    -- Open prompt selector with optional config
 chat.select_model()           -- Open model selector
@@ -519,7 +495,6 @@ cd CopilotChat.nvim
 2. Install development dependencies:
 
 ```bash
-# Install pre-commit hooks
 make install-pre-commit
 ```
 
@@ -626,7 +601,12 @@ Thanks goes to these wonderful people ([emoji key](https://allcontributors.org/d
       <td align="center" valign="top" width="14.28%"><a href="https://a14n.net"><img src="https://avatars.githubusercontent.com/u/509703?v=4?s=100" width="100px;" alt="Aaron D Borden"/><br /><sub><b>Aaron D Borden</b></sub></a><br /><a href="https://github.com/CopilotC-Nvim/CopilotChat.nvim/commits?author=adborden" title="Code">💻</a></td>
       <td align="center" valign="top" width="14.28%"><a href="https://github.com/AtifChy"><img src="https://avatars.githubusercontent.com/u/42291930?v=4?s=100" width="100px;" alt="Md. Iftakhar Awal Chowdhury"/><br /><sub><b>Md. Iftakhar Awal Chowdhury</b></sub></a><br /><a href="https://github.com/CopilotC-Nvim/CopilotChat.nvim/commits?author=AtifChy" title="Code">💻</a> <a href="https://github.com/CopilotC-Nvim/CopilotChat.nvim/commits?author=AtifChy" title="Documentation">📖</a></td>
       <td align="center" valign="top" width="14.28%"><a href="https://github.com/danilohorta"><img src="https://avatars.githubusercontent.com/u/214497460?v=4?s=100" width="100px;" alt="Danilo Horta"/><br /><sub><b>Danilo Horta</b></sub></a><br /><a href="https://github.com/CopilotC-Nvim/CopilotChat.nvim/commits?author=danilohorta" title="Code">💻</a></td>
-      <td align="center" valign="top" width="14.28%"><a href="https://mihamina.rktmb.org"><img src="https://avatars.githubusercontent.com/u/488088?v=4?s=100" width="100px;" alt="Mihamina Rakotomandimby"/><br /><sub><b>Mihamina Rakotomandimby</b></sub></a><br /><a href="https://github.com/CopilotC-Nvim/CopilotChat.nvim/commits?author=rakotomandimby" title="Documentation">📖</a></td>
+      <td align="center" valign="top" width="14.28%"><a href="https://mihamina.rktmb.org"><img src="https://avatars.githubusercontent.com/u/488088?v=4?s=100" width="100px;" alt="Mihamina Rakotomandimby"/><br /><sub><b>Mihamina Rakotomandimby</b></sub></a><br /><a href="https://github.com/CopilotC-Nvim/CopilotChat.nvim/commits?author=rakotomandimby" title="Documentation">📖</a> <a href="https://github.com/CopilotC-Nvim/CopilotChat.nvim/commits?author=rakotomandimby" title="Code">💻</a></td>
+      <td align="center" valign="top" width="14.28%"><a href="http://ajmalshajahan.me"><img src="https://avatars.githubusercontent.com/u/23806715?v=4?s=100" width="100px;" alt="Ajmal S"/><br /><sub><b>Ajmal S</b></sub></a><br /><a href="https://github.com/CopilotC-Nvim/CopilotChat.nvim/commits?author=AjmalShajahan" title="Code">💻</a></td>
+    </tr>
+    <tr>
+      <td align="center" valign="top" width="14.28%"><a href="https://github.com/samiulsami"><img src="https://avatars.githubusercontent.com/u/33352407?v=4?s=100" width="100px;" alt="Samiul Islam"/><br /><sub><b>Samiul Islam</b></sub></a><br /><a href="https://github.com/CopilotC-Nvim/CopilotChat.nvim/commits?author=samiulsami" title="Code">💻</a></td>
+      <td align="center" valign="top" width="14.28%"><a href="https://ruicsh.github.io"><img src="https://avatars.githubusercontent.com/u/8294038?v=4?s=100" width="100px;" alt="Rui Costa"/><br /><sub><b>Rui Costa</b></sub></a><br /><a href="https://github.com/CopilotC-Nvim/CopilotChat.nvim/commits?author=ruicsh" title="Code">💻</a></td>
     </tr>
   </tbody>
 </table>
diff --git a/doc/CopilotChat.txt b/doc/CopilotChat.txt
index 2c3086ef..f9b63e92 100644
--- a/doc/CopilotChat.txt
+++ b/doc/CopilotChat.txt
@@ -1,4 +1,4 @@
-*CopilotChat.txt*          For NVIM v0.8.0         Last change: 2025 August 12
+*CopilotChat.txt*          For NVIM v0.8.0         Last change: 2025 August 27
 
 ==============================================================================
 Table of Contents                              *CopilotChat-table-of-contents*
@@ -23,7 +23,6 @@ Table of Contents                              *CopilotChat-table-of-contents*
   - Highlights                                        |CopilotChat-highlights|
   - Prompts                                              |CopilotChat-prompts|
   - Functions                                          |CopilotChat-functions|
-  - Selections                                        |CopilotChat-selections|
   - Providers                                          |CopilotChat-providers|
 5. API Reference                                   |CopilotChat-api-reference|
   - Core                                                    |CopilotChat-core|
@@ -128,7 +127,6 @@ VIM-PLUG                                                *CopilotChat-vim-plug*
 - **Sticky Prompts** (`> <text>`) - Persist context across single chat session
 - **Models** (`$<model>`) - Specify which AI model to use for the chat
 - **Prompts** (`/PromptName`) - Use predefined prompt templates for common tasks
-- **Selection** - Automatically includes current user selection in prompts
 
 
 EXAMPLES                                                *CopilotChat-examples*
@@ -232,6 +230,8 @@ All predefined functions belong to the `copilot` group.
 
   register      Provides access to specified Vim register #register:+
 
+  selection     Includes the current visual selection     #selection
+
   url           Fetches content from a specified URL      #url:https://...
   ------------------------------------------------------------------------------
 
@@ -294,12 +294,13 @@ WINDOW & APPEARANCE                          *CopilotChat-window-&-appearance*
       },
     
       headers = {
-        user = '👤 You: ',
-        assistant = '🤖 Copilot: ',
-        tool = '🔧 Tool: ',
+        user = '👤 You',
+        assistant = '🤖 Copilot',
+        tool = '🔧 Tool',
       },
+    
       separator = '━━',
-      show_folds = false, -- Disable folding for cleaner look
+      auto_fold = true, -- Automatically folds non-assistant messages
     }
 <
 
@@ -333,6 +334,7 @@ Types of copilot highlights:
 
 - `CopilotChatHeader` - Header highlight in chat buffer
 - `CopilotChatSeparator` - Separator highlight in chat buffer
+- `CopilotChatSelection` - Selection highlight in source buffer
 - `CopilotChatStatus` - Status and spinner in chat buffer
 - `CopilotChatHelp` - Help text in chat buffer
 - `CopilotChatResource` - Resource highlight in chat buffer (e.g. `#file`, `#gitdiff`)
@@ -340,7 +342,6 @@ Types of copilot highlights:
 - `CopilotChatPrompt` - Prompt highlight in chat buffer (e.g. `/Explain`, `/Review`)
 - `CopilotChatModel` - Model highlight in chat buffer (e.g. `$gpt-4.1`)
 - `CopilotChatUri` - URI highlight in chat buffer (e.g. `##https://...`)
-- `CopilotChatSelection` - Selection highlight in source buffer
 - `CopilotChatAnnotation` - Annotation highlight in chat buffer (file headers, tool call headers, tool call body)
 
 
@@ -361,7 +362,7 @@ Define your own prompts in the configuration:
           system_prompt = 'You are fascinated by pirates, so please respond in pirate speak.',
         },
         NiceInstructions = {
-          system_prompt = 'You are a nice coding tutor, so please respond in a friendly and helpful manner.' .. require('CopilotChat.config.prompts').COPILOT_BASE.system_prompt,
+          system_prompt = 'You are a nice coding tutor, so please respond in a friendly and helpful manner.',
         }
       }
     }
@@ -404,28 +405,6 @@ Define your own functions in the configuration with input handling and schema:
 <
 
 
-SELECTIONS                                            *CopilotChat-selections*
-
-Control what content is automatically included:
-
->lua
-    {
-      -- Use visual selection, fallback to current line
-      selection = function(source)
-        return require('CopilotChat.select').visual(source) or
-               require('CopilotChat.select').line(source)
-      end,
-    }
-<
-
-**Available selections:**
-
-- `require('CopilotChat.select').visual` - Current visual selection
-- `require('CopilotChat.select').buffer` - Entire buffer content
-- `require('CopilotChat.select').line` - Current line content
-- `require('CopilotChat.select').unnamed` - Unnamed register (last deleted/changed/yanked)
-
-
 PROVIDERS                                              *CopilotChat-providers*
 
 Add custom AI providers:
@@ -504,10 +483,6 @@ CORE                                                        *CopilotChat-core*
     chat.get_source()             -- Get the current source buffer and window
     chat.set_source(winnr)        -- Set the source window
     
-    -- Selection Management
-    chat.get_selection()                                   -- Get the current selection
-    chat.set_selection(bufnr, start_line, end_line, clear) -- Set or clear selection
-    
     -- Prompt & Model Management
     chat.select_prompt(config)    -- Open prompt selector with optional config
     chat.select_model()           -- Open model selector
@@ -600,7 +575,6 @@ To set up the environment:
 1. Install development dependencies:
 
 >bash
-    # Install pre-commit hooks
     make install-pre-commit
 <
 
@@ -628,7 +602,7 @@ See CONTRIBUTING.md </CONTRIBUTING.md> for detailed guidelines.
 Thanks goes to these wonderful people (emoji key
 <https://allcontributors.org/docs/en/emoji-key>):
 
-gptlang💻 📖Dung Duc Huynh (Kaka)💻 📖Ahmed Haracic💻Trí Thiện Nguyễn💻He Zhizhou💻Guruprakash Rajakkannu💻kristofka💻PostCyberPunk📖Katsuhiko Nishimra💻Erno Hopearuoho💻Shaun Garwood💻neutrinoA4💻 📖Jack Muratore💻Adriel Velazquez💻 📖Tomas Slusny💻 📖Nisal📖Tobias Gårdhus📖Petr Dlouhý📖Dylan Madisetti💻Aaron Weisberg💻 📖Jose Tlacuilo💻 📖Kevin Traver💻 📖dTry💻Arata Furukawa💻Ling💻Ivan Frolov💻Folke Lemaitre💻 📖GitMurf💻Dmitrii Lipin💻jinzhongjia📖guill💻Sjon-Paul Brown💻Renzo Mondragón💻 📖fjchen7💻Radosław Woźniak💻JakubPecenka💻thomastthai📖Tomáš Janoušek💻Toddneal Stallworth📖Sergey Alexandrov💻Léopold Mebazaa💻JunKi Jin💻abdennourzahaf📖Josiah💻Tony Fischer💻 📖Kohei Wada💻Sebastian Yaghoubi📖johncming💻Rokas Brazdžionis💻Sola📖 💻Mani Chandra💻Nischal Basuti📖Teo Ljungberg💻Joe Price💻Yufan You📖 💻Manish Kumar💻Anton Ždanov📖 💻Fredrik Averpil💻Aaron D Borden💻Md. Iftakhar Awal Chowdhury💻 📖Danilo Horta💻Mihamina Rakotomandimby📖This project follows the all-contributors
+gptlang💻 📖Dung Duc Huynh (Kaka)💻 📖Ahmed Haracic💻Trí Thiện Nguyễn💻He Zhizhou💻Guruprakash Rajakkannu💻kristofka💻PostCyberPunk📖Katsuhiko Nishimra💻Erno Hopearuoho💻Shaun Garwood💻neutrinoA4💻 📖Jack Muratore💻Adriel Velazquez💻 📖Tomas Slusny💻 📖Nisal📖Tobias Gårdhus📖Petr Dlouhý📖Dylan Madisetti💻Aaron Weisberg💻 📖Jose Tlacuilo💻 📖Kevin Traver💻 📖dTry💻Arata Furukawa💻Ling💻Ivan Frolov💻Folke Lemaitre💻 📖GitMurf💻Dmitrii Lipin💻jinzhongjia📖guill💻Sjon-Paul Brown💻Renzo Mondragón💻 📖fjchen7💻Radosław Woźniak💻JakubPecenka💻thomastthai📖Tomáš Janoušek💻Toddneal Stallworth📖Sergey Alexandrov💻Léopold Mebazaa💻JunKi Jin💻abdennourzahaf📖Josiah💻Tony Fischer💻 📖Kohei Wada💻Sebastian Yaghoubi📖johncming💻Rokas Brazdžionis💻Sola📖 💻Mani Chandra💻Nischal Basuti📖Teo Ljungberg💻Joe Price💻Yufan You📖 💻Manish Kumar💻Anton Ždanov📖 💻Fredrik Averpil💻Aaron D Borden💻Md. Iftakhar Awal Chowdhury💻 📖Danilo Horta💻Mihamina Rakotomandimby📖 💻Ajmal S💻Samiul Islam💻Rui Costa💻This project follows the all-contributors
 <https://github.com/all-contributors/all-contributors> specification.
 Contributions of any kind are welcome!
 
diff --git a/lua/CopilotChat/client.lua b/lua/CopilotChat/client.lua
index f2dba5b0..fb2929a0 100644
--- a/lua/CopilotChat/client.lua
+++ b/lua/CopilotChat/client.lua
@@ -1,7 +1,6 @@
 ---@class CopilotChat.client.AskOptions
 ---@field headless boolean
 ---@field history table<CopilotChat.client.Message>
----@field selection CopilotChat.select.Selection?
 ---@field tools table<CopilotChat.client.Tool>?
 ---@field resources table<CopilotChat.client.Resource>?
 ---@field system_prompt string
@@ -32,11 +31,16 @@
 ---@field description string description of the tool
 ---@field schema table? schema of the tool
 
+---@class CopilotChat.client.ResourceAnnotations
+---@field start_line number?
+---@field end_line number?
+
 ---@class CopilotChat.client.Resource
 ---@field data string
 ---@field name string?
 ---@field mimetype string?
 ---@field uri string?
+---@field annotations CopilotChat.client.ResourceAnnotations?
 
 ---@class CopilotChat.client.Model
 ---@field provider string?
@@ -54,7 +58,11 @@ local constants = require('CopilotChat.constants')
 local notify = require('CopilotChat.notify')
 local tiktoken = require('CopilotChat.tiktoken')
 local utils = require('CopilotChat.utils')
-local class = utils.class
+local curl = require('CopilotChat.utils.curl')
+local class = require('CopilotChat.utils.class')
+local files = require('CopilotChat.utils.files')
+local orderedmap = require('CopilotChat.utils.orderedmap')
+local stringbuffer = require('CopilotChat.utils.stringbuffer')
 
 --- Constants
 local RESOURCE_SHORT_FORMAT = '# %s\n```%s start_line=% end_line=%s\n%s\n```'
@@ -91,7 +99,7 @@ local function generate_resource_block(content, mimetype, name, path, start_line
   end
 
   local updated_content = table.concat(lines, '\n')
-  local filetype = utils.mimetype_to_filetype(mimetype or 'text')
+  local filetype = files.mimetype_to_filetype(mimetype or 'text')
   if not start_line then
     start_line = 1
   end
@@ -106,29 +114,6 @@ local function generate_resource_block(content, mimetype, name, path, start_line
   end
 end
 
---- Generate messages for the given selection
---- @param selection CopilotChat.select.Selection
---- @return CopilotChat.client.Message?
-local function generate_selection_message(selection)
-  local content = selection.content
-
-  if not content or content == '' then
-    return nil
-  end
-
-  return {
-    content = generate_resource_block(
-      content,
-      selection.filetype,
-      "User's active selection",
-      selection.filename,
-      selection.start_line,
-      selection.end_line
-    ),
-    role = constants.ROLE.USER,
-  }
-end
-
 --- Generate messages for the given resources
 --- @param resources CopilotChat.client.Resource[]
 --- @return table<CopilotChat.client.Message>
@@ -139,8 +124,17 @@ local function generate_resource_messages(resources)
       return resource.data and resource.data ~= ''
     end)
     :map(function(resource)
+      local start_line = resource.annotations and resource.annotations.start_line or 1
+      local end_line = resource.annotations and resource.annotations.end_line or nil
       return {
-        content = generate_resource_block(resource.data, resource.mimetype, resource.uri, resource.name, 1, nil),
+        content = generate_resource_block(
+          resource.data,
+          resource.mimetype,
+          resource.uri,
+          resource.name,
+          start_line,
+          end_line
+        ),
         role = constants.ROLE.USER,
       }
     end)
@@ -196,7 +190,7 @@ end)
 ---@param supported_method? string: The method to filter providers by (optional)
 ---@return OrderedMap<string, CopilotChat.config.providers.Provider>
 function Client:get_providers(supported_method)
-  local out = utils.ordered_map()
+  local out = orderedmap()
 
   if not self.provider_resolver then
     return out
@@ -357,22 +351,16 @@ function Client:ask(prompt, opts)
   end
 
   local history = not opts.headless and vim.deepcopy(opts.history) or {}
-  local tool_calls = utils.ordered_map()
+  local tool_calls = orderedmap()
   local generated_messages = {}
-  local selection_message = opts.selection and generate_selection_message(opts.selection)
   local resource_messages = generate_resource_messages(opts.resources)
 
-  if selection_message then
-    table.insert(generated_messages, selection_message)
-  end
-
   if max_tokens then
     -- Count required tokens that we cannot reduce
-    local selection_tokens = selection_message and tiktoken:count(selection_message.content) or 0
     local prompt_tokens = tiktoken:count(prompt)
     local system_tokens = tiktoken:count(opts.system_prompt)
     local resource_tokens = #resource_messages > 0 and tiktoken:count(resource_messages[1].content) or 0
-    local required_tokens = prompt_tokens + system_tokens + selection_tokens + resource_tokens
+    local required_tokens = prompt_tokens + system_tokens + resource_tokens
 
     -- Calculate how many tokens we can use for history
     local history_limit = max_tokens - required_tokens
@@ -408,8 +396,8 @@ function Client:ask(prompt, opts)
   local errored = nil
   local finished = false
   local token_count = 0
-  local response_content_buffer = utils.string_buffer()
-  local response_reasoning_buffer = utils.string_buffer()
+  local response_content_buffer = stringbuffer()
+  local response_reasoning_buffer = stringbuffer()
 
   local function finish_stream(err, job)
     if err then
@@ -463,11 +451,11 @@ function Client:ask(prompt, opts)
     end
 
     if out.content then
-      response_content_buffer:add(out.content)
+      response_content_buffer:put(out.content)
     end
 
     if out.reasoning then
-      response_reasoning_buffer:add(out.reasoning)
+      response_reasoning_buffer:put(out.reasoning)
     end
 
     if opts.on_progress then
@@ -543,7 +531,7 @@ function Client:ask(prompt, opts)
     args.stream = stream_func
   end
 
-  local response, err = utils.curl_post(provider.get_url(options), args)
+  local response, err = curl.post(provider.get_url(options), args)
 
   if not opts.headless then
     if self.current_job ~= job_id then
diff --git a/lua/CopilotChat/completion.lua b/lua/CopilotChat/completion.lua
index a32141eb..97b3e9d4 100644
--- a/lua/CopilotChat/completion.lua
+++ b/lua/CopilotChat/completion.lua
@@ -146,7 +146,7 @@ function M.complete(without_input)
   if not without_input and vim.startswith(prefix, '#') and vim.endswith(prefix, ':') then
     local found_tool = config.functions[prefix:sub(2, -2)]
     local found_schema = found_tool and functions.parse_schema(found_tool)
-    if found_tool and found_schema then
+    if found_tool and found_schema and found_tool.uri then
       async.run(function()
         local value = functions.enter_input(found_schema, source)
         if not value then
@@ -167,6 +167,10 @@ function M.complete(without_input)
       local items = M.items()
       utils.schedule_main()
 
+      if not vim.api.nvim_win_is_valid(win) then
+        return
+      end
+
       local row_changed = vim.api.nvim_win_get_cursor(win)[1] ~= row
       local mode = vim.api.nvim_get_mode().mode
       if row_changed or not (mode == 'i' or mode == 'ic') then
diff --git a/lua/CopilotChat/config.lua b/lua/CopilotChat/config.lua
index 48f5e96a..b525e995 100644
--- a/lua/CopilotChat/config.lua
+++ b/lua/CopilotChat/config.lua
@@ -14,16 +14,16 @@
 ---@field blend number?
 
 ---@class CopilotChat.config.Shared
----@field system_prompt string?
+---@field system_prompt nil|string|fun(source: CopilotChat.source):string
 ---@field model string?
 ---@field tools string|table<string>|nil
+---@field resources string|table<string>|nil
 ---@field sticky string|table<string>|nil
 ---@field language string?
 ---@field temperature number?
 ---@field headless boolean?
----@field callback nil|fun(response: string, source: CopilotChat.source)
+---@field callback nil|fun(response: CopilotChat.client.Message, source: CopilotChat.source)
 ---@field remember_as_sticky boolean?
----@field selection false|nil|fun(source: CopilotChat.source):CopilotChat.select.Selection?
 ---@field window CopilotChat.config.Window?
 ---@field show_help boolean?
 ---@field show_folds boolean?
@@ -31,8 +31,10 @@
 ---@field highlight_headers boolean?
 ---@field auto_follow_cursor boolean?
 ---@field auto_insert_mode boolean?
+---@field auto_fold boolean?
 ---@field insert_at_end boolean?
 ---@field clear_chat_on_new_prompt boolean?
+---@field stop_on_function_failure boolean?
 
 --- CopilotChat default configuration
 ---@class CopilotChat.config.Config : CopilotChat.config.Shared
@@ -40,6 +42,7 @@
 ---@field log_level 'trace'|'debug'|'info'|'warn'|'error'|'fatal'?
 ---@field proxy string?
 ---@field allow_insecure boolean?
+---@field selection 'visual'|'unnamed'|nil
 ---@field chat_autocomplete boolean?
 ---@field log_path string?
 ---@field history_path string?
@@ -53,10 +56,11 @@ return {
 
   -- Shared config starts here (can be passed to functions at runtime and configured via setup function)
 
-  system_prompt = 'COPILOT_INSTRUCTIONS', -- System prompt to use (can be specified manually in prompt via /).
+  system_prompt = require('CopilotChat.config.prompts').COPILOT_INSTRUCTIONS.system_prompt, -- System prompt to use (can be specified manually in prompt via /).
 
   model = 'gpt-4.1', -- Default model to use, see ':CopilotChatModels' for available models (can be specified manually in prompt via $).
   tools = nil, -- Default tool or array of tools (or groups) to share with LLM (can be specified manually in prompt via @).
+  resources = 'selection', -- Default resources to share with LLM (can be specified manually in prompt via #).
   sticky = nil, -- Default sticky prompt or array of sticky prompts to use at start of every new chat (can be specified manually in prompt via >).
   language = 'English', -- Default language to use for answers
 
@@ -65,9 +69,6 @@ return {
   callback = nil, -- Function called when full response is received
   remember_as_sticky = true, -- Remember config as sticky prompts when asking questions
 
-  -- default selection
-  selection = require('CopilotChat.select').visual,
-
   -- default window options
   window = {
     layout = 'vertical', -- 'vertical', 'horizontal', 'float', 'replace', or a function that returns the layout
@@ -86,12 +87,14 @@ return {
 
   show_help = true, -- Shows help message as virtual lines when waiting for user input
   show_folds = true, -- Shows folds for sections in chat
+  auto_fold = false, -- Automatically non-assistant messages in chat (requires 'show_folds' to be true)
   highlight_selection = true, -- Highlight selection
   highlight_headers = true, -- Highlight headers in chat
   auto_follow_cursor = true, -- Auto-follow cursor in chat
   auto_insert_mode = false, -- Automatically enter insert mode when opening window and on new prompt
   insert_at_end = false, -- Move cursor to end of buffer when inserting text
   clear_chat_on_new_prompt = false, -- Clears chat on every new prompt
+  stop_on_function_failure = false, -- Stop processing prompt if any function fails (preserves quota)
 
   -- Static config starts here (can be configured only via setup function)
 
@@ -100,6 +103,7 @@ return {
   proxy = nil, -- [protocol://]host[:port] Use this proxy
   allow_insecure = false, -- Allow insecure server connections
 
+  selection = 'visual', -- Selection source
   chat_autocomplete = true, -- Enable chat autocompletion (when disabled, requires manual `mappings.complete` trigger)
 
   log_path = vim.fn.stdpath('state') .. '/CopilotChat.log', -- Default path to log file
diff --git a/lua/CopilotChat/config/functions.lua b/lua/CopilotChat/config/functions.lua
index 9050d267..2f085705 100644
--- a/lua/CopilotChat/config/functions.lua
+++ b/lua/CopilotChat/config/functions.lua
@@ -1,12 +1,13 @@
 local resources = require('CopilotChat.resources')
 local utils = require('CopilotChat.utils')
+local files = require('CopilotChat.utils.files')
 
 ---@class CopilotChat.config.functions.Function
 ---@field description string?
 ---@field schema table?
 ---@field group string?
 ---@field uri string?
----@field resolve fun(input: table, source: CopilotChat.source, prompt: string):table<CopilotChat.client.Resource>
+---@field resolve fun(input: table, source: CopilotChat.source):CopilotChat.client.Resource[]
 
 ---@type table<string, CopilotChat.config.functions.Function>
 return {
@@ -23,7 +24,7 @@ return {
           type = 'string',
           description = 'Path to file to include in chat context.',
           enum = function(source)
-            return utils.glob(source.cwd(), {
+            return files.glob(source.cwd(), {
               max_count = 0,
             })
           end,
@@ -67,7 +68,7 @@ return {
     },
 
     resolve = function(input, source)
-      local files = utils.glob(source.cwd(), {
+      local out = files.glob(source.cwd(), {
         pattern = input.pattern,
       })
 
@@ -75,7 +76,7 @@ return {
         {
           uri = 'files://glob/' .. input.pattern,
           mimetype = 'text/plain',
-          data = table.concat(files, '\n'),
+          data = table.concat(out, '\n'),
         },
       }
     end,
@@ -98,7 +99,7 @@ return {
     },
 
     resolve = function(input, source)
-      local files = utils.grep(source.cwd(), {
+      local out = files.grep(source.cwd(), {
         pattern = input.pattern,
       })
 
@@ -106,7 +107,7 @@ return {
         {
           uri = 'files://grep/' .. input.pattern,
           mimetype = 'text/plain',
-          data = table.concat(files, '\n'),
+          data = table.concat(out, '\n'),
         },
       }
     end,
@@ -214,6 +215,33 @@ return {
     end,
   },
 
+  selection = {
+    group = 'copilot',
+    uri = 'neovim://selection',
+    description = 'Includes the content of the current visual selection. Useful for discussing specific code snippets or text blocks.',
+
+    resolve = function(_, source)
+      utils.schedule_main()
+      local selection = require('CopilotChat.select').get(source.bufnr)
+      if not selection then
+        return {}
+      end
+
+      return {
+        {
+          uri = 'neovim://selection',
+          name = selection.filename,
+          mimetype = files.mimetype_to_filetype(selection.filetype),
+          data = selection.content,
+          annotations = {
+            start_line = selection.start_line,
+            end_line = selection.end_line,
+          },
+        },
+      }
+    end,
+  },
+
   quickfix = {
     group = 'copilot',
     uri = 'neovim://quickfix',
@@ -280,7 +308,7 @@ return {
         scope = {
           type = 'string',
           description = 'Scope of buffers to use for retrieving diagnostics.',
-          enum = { 'current', 'listed', 'visible' },
+          enum = { 'current', 'listed', 'visible', 'selection' },
           default = 'current',
         },
         severity = {
@@ -299,7 +327,7 @@ return {
       local buffers = {}
 
       -- Get buffers based on scope
-      if scope == 'current' then
+      if scope == 'current' or scope == 'selection' then
         if source and source.bufnr and utils.buf_valid(source.bufnr) then
           buffers = { source.bufnr }
         end
@@ -317,6 +345,21 @@ return {
         end, vim.api.nvim_list_bufs())
       end
 
+      -- By default, collect from the whole buffer
+      local selection_start_line = 1
+      local selection_end_line = vim.api.nvim_buf_line_count(source.bufnr)
+      -- Determine selection range if scope is 'selection'
+      if scope == 'selection' then
+        local select = require('CopilotChat.select')
+        local selection = select.get(source.bufnr)
+        if selection then
+          selection_start_line = selection.start_line
+          selection_end_line = selection.end_line
+        else
+          return out
+        end
+      end
+
       -- Collect diagnostics for each buffer
       for _, bufnr in ipairs(buffers) do
         local name = vim.api.nvim_buf_get_name(bufnr)
@@ -329,20 +372,24 @@ return {
         if #diagnostics > 0 then
           local diag_lines = {}
           for _, diag in ipairs(diagnostics) do
-            local severity = vim.diagnostic.severity[diag.severity] or 'UNKNOWN'
-            local line_text = vim.api.nvim_buf_get_lines(bufnr, diag.lnum, diag.lnum + 1, false)[1] or ''
-
-            table.insert(
-              diag_lines,
-              string.format(
-                '%s line=%d-%d: %s\n  > %s',
-                severity,
-                diag.lnum + 1,
-                diag.end_lnum and (diag.end_lnum + 1) or (diag.lnum + 1),
-                diag.message,
-                line_text
+            -- Diagnostics.lnum are 0-indexed, so add 1 for comparison
+            local diag_lnum = diag.lnum + 1
+            if diag_lnum >= selection_start_line and diag_lnum <= selection_end_line then
+              local severity = vim.diagnostic.severity[diag.severity] or 'UNKNOWN'
+              local line_text = vim.api.nvim_buf_get_lines(bufnr, diag.lnum, diag.lnum + 1, false)[1] or ''
+
+              table.insert(
+                diag_lines,
+                string.format(
+                  '%s line=%d-%d: %s\n  > %s',
+                  severity,
+                  diag.lnum + 1,
+                  diag.end_lnum and (diag.end_lnum + 1) or (diag.lnum + 1),
+                  diag.message,
+                  line_text
+                )
               )
-            )
+            end
           end
 
           table.insert(out, {
diff --git a/lua/CopilotChat/config/mappings.lua b/lua/CopilotChat/config/mappings.lua
index 4928a876..3b0d06b9 100644
--- a/lua/CopilotChat/config/mappings.lua
+++ b/lua/CopilotChat/config/mappings.lua
@@ -2,7 +2,9 @@ local async = require('plenary.async')
 local copilot = require('CopilotChat')
 local client = require('CopilotChat.client')
 local constants = require('CopilotChat.constants')
+local select = require('CopilotChat.select')
 local utils = require('CopilotChat.utils')
+local files = require('CopilotChat.utils.files')
 
 ---@class CopilotChat.config.mappings.Diff
 ---@field change string
@@ -14,28 +16,38 @@ local utils = require('CopilotChat.utils')
 ---@field bufnr number?
 
 --- Get diff data from a block
+---@param bufnr number
 ---@param block CopilotChat.ui.chat.Block?
 ---@return CopilotChat.config.mappings.Diff?
-local function get_diff(block)
+local function get_diff(bufnr, block)
   -- If no block found, return nil
   if not block then
     return nil
   end
 
-  -- Initialize variables with selection if available
   local header = block.header
-  local selection = copilot.get_selection()
-  local reference = selection and selection.content
-  local start_line = selection and selection.start_line
-  local end_line = selection and selection.end_line
-  local filename = selection and selection.filename
-  local filetype = selection and selection.filetype
-  local bufnr = selection and selection.bufnr
+  local selection = select.get(bufnr)
+  local filename = nil
+  local filetype = nil
+  local start_line = nil
+  local end_line = nil
+  local reference = nil
+  local bufnr = nil
+
+  if selection then
+    -- If we have a selection, use it as default source of truth
+    filename = selection.filename
+    filetype = selection.filetype
+    start_line = selection.start_line
+    end_line = selection.end_line
+    reference = selection.content
+    bufnr = selection.bufnr
+  end
 
   -- If we have header info, use it as source of truth
   if header.start_line and header.end_line then
-    filename = utils.uri_to_filename(header.filename)
-    filetype = header.filetype or utils.filetype(filename)
+    filename = files.uri_to_filename(header.filename)
+    filetype = header.filetype or files.filetype(filename)
     start_line = header.start_line
     end_line = header.end_line
 
@@ -43,7 +55,7 @@ local function get_diff(block)
     bufnr = nil
     for _, win in ipairs(vim.api.nvim_list_wins()) do
       local win_buf = vim.api.nvim_win_get_buf(win)
-      if utils.filename_same(vim.api.nvim_buf_get_name(win_buf), header.filename) then
+      if files.filename_same(vim.api.nvim_buf_get_name(win_buf), header.filename) then
         bufnr = win_buf
         break
       end
@@ -51,7 +63,8 @@ local function get_diff(block)
 
     -- If we found a valid buffer, get the reference content
     if bufnr and utils.buf_valid(bufnr) then
-      reference = table.concat(vim.api.nvim_buf_get_lines(bufnr, start_line - 1, end_line, false), '\n')
+      local lines = vim.api.nvim_buf_get_lines(bufnr, start_line - 1, end_line, false)
+      reference = table.concat(lines, '\n')
       filetype = vim.bo[bufnr].filetype
     end
   end
@@ -87,7 +100,7 @@ local function prepare_diff_buffer(diff, source)
   if not diff_bufnr then
     -- Try to find matching buffer first
     for _, buf in ipairs(vim.api.nvim_list_bufs()) do
-      if utils.filename_same(vim.api.nvim_buf_get_name(buf), diff.filename) then
+      if files.filename_same(vim.api.nvim_buf_get_name(buf), diff.filename) then
         diff_bufnr = buf
         break
       end
@@ -212,7 +225,7 @@ return {
         return
       end
 
-      local lines = vim.split(message.content, '\n')
+      local lines = utils.split_lines(message.content)
       local new_lines = {}
       local changed = false
 
@@ -235,28 +248,30 @@ return {
     normal = '<C-y>',
     insert = '<C-y>',
     callback = function(source)
-      local diff = get_diff(copilot.chat:get_block(constants.ROLE.ASSISTANT, true))
+      local diff = get_diff(source.bufnr, copilot.chat:get_block(constants.ROLE.ASSISTANT, true))
       diff = prepare_diff_buffer(diff, source)
       if not diff then
         return
       end
 
-      local lines = vim.split(diff.change, '\n', { trimempty = false })
+      local lines = utils.split_lines(diff.change)
       vim.api.nvim_buf_set_lines(diff.bufnr, diff.start_line - 1, diff.end_line, false, lines)
-      copilot.set_selection(diff.bufnr, diff.start_line, diff.start_line + #lines - 1)
+      select.set(source.bufnr, source.winnr, diff.start_line, diff.start_line + #lines - 1)
+      select.highlight(source.bufnr)
     end,
   },
 
   jump_to_diff = {
     normal = 'gj',
     callback = function(source)
-      local diff = get_diff(copilot.chat:get_block(constants.ROLE.ASSISTANT, true))
+      local diff = get_diff(source.bufnr, copilot.chat:get_block(constants.ROLE.ASSISTANT, true))
       diff = prepare_diff_buffer(diff, source)
       if not diff then
         return
       end
 
-      copilot.set_selection(diff.bufnr, diff.start_line, diff.end_line)
+      select.set(source.bufnr, source.winnr, diff.start_line, diff.end_line)
+      select.highlight(source.bufnr)
     end,
   },
 
@@ -288,32 +303,26 @@ return {
 
   quickfix_diffs = {
     normal = 'gqd',
-    callback = function()
-      local selection = copilot.get_selection()
+    callback = function(source)
       local items = {}
 
       for _, message in ipairs(copilot.chat.messages) do
         if message.section then
           for _, block in ipairs(message.section.blocks) do
-            local header = block.header
-
-            if not header.start_line and selection then
-              header.filename = selection.filename .. ' (selection)'
-              header.start_line = selection.start_line
-              header.end_line = selection.end_line
-            end
+            local diff = get_diff(source.bufnr, block)
+            if diff then
+              local text = string.format('%s (%s)', diff.filename, diff.filetype)
+              if diff.start_line and diff.end_line then
+                text = text .. string.format(' [lines %d-%d]', diff.start_line, diff.end_line)
+              end
 
-            local text = string.format('%s (%s)', header.filename, header.filetype)
-            if header.start_line and header.end_line then
-              text = text .. string.format(' [lines %d-%d]', header.start_line, header.end_line)
+              table.insert(items, {
+                bufnr = copilot.chat.bufnr,
+                lnum = block.start_line,
+                end_lnum = block.end_line,
+                text = text,
+              })
             end
-
-            table.insert(items, {
-              bufnr = copilot.chat.bufnr,
-              lnum = block.start_line,
-              end_lnum = block.end_line,
-              text = text,
-            })
           end
         end
 
@@ -340,7 +349,7 @@ return {
     normal = 'gd',
     full_diff = false, -- Show full diff instead of unified diff when showing diff window
     callback = function(source)
-      local diff = get_diff(copilot.chat:get_block(constants.ROLE.ASSISTANT, true))
+      local diff = get_diff(source.bufnr, copilot.chat:get_block(constants.ROLE.ASSISTANT, true))
       diff = prepare_diff_buffer(diff, source)
       if not diff then
         return
@@ -352,45 +361,52 @@ return {
       }
 
       if copilot.config.mappings.show_diff.full_diff then
-        local modified = utils.buf_valid(diff.bufnr) and vim.api.nvim_buf_get_lines(diff.bufnr, 0, -1, false) or {}
+        local original = utils.buf_valid(diff.bufnr) and vim.api.nvim_buf_get_lines(diff.bufnr, 0, -1, false) or {}
 
-        -- Apply all diffs from same file
-        if #modified > 0 then
+        if #original > 0 then
           -- Find all diffs from the same file in this section
           local message = copilot.chat:get_message(constants.ROLE.ASSISTANT, true)
           local section = message and message.section
           local same_file_diffs = {}
           if section then
             for _, block in ipairs(section.blocks) do
-              local block_diff = get_diff(block)
+              local block_diff = get_diff(source.bufnr, block)
               if block_diff and block_diff.bufnr == diff.bufnr then
                 table.insert(same_file_diffs, block_diff)
               end
             end
+          end
 
-            -- Sort diffs bottom to top to preserve line numbering
-            table.sort(same_file_diffs, function(a, b)
-              return a.start_line > b.start_line
-            end)
+          -- Ensure we at least apply the current diff
+          if #same_file_diffs == 0 then
+            table.insert(same_file_diffs, diff)
           end
 
-          for _, file_diff in ipairs(same_file_diffs) do
-            local start_idx = file_diff.start_line
-            local end_idx = file_diff.end_line
-            for _ = start_idx, end_idx do
-              table.remove(modified, start_idx)
+          -- Sort diffs by start_line in descending order (apply from bottom to top)
+          table.sort(same_file_diffs, function(a, b)
+            return a.start_line > b.start_line
+          end)
+
+          local result = vim.deepcopy(original)
+
+          -- Apply diffs from bottom to top so line numbers remain valid
+          for _, d in ipairs(same_file_diffs) do
+            local change_lines = utils.split_lines(d.change)
+
+            -- Remove original lines (from end to start to avoid index shifting)
+            for i = d.end_line, d.start_line, -1 do
+              if result[i] then
+                table.remove(result, i)
+              end
             end
-            local change_lines = vim.split(file_diff.change, '\n')
-            for i, line in ipairs(change_lines) do
-              table.insert(modified, start_idx + i, line)
+
+            -- Insert replacement lines at start_line
+            for i = #change_lines, 1, -1 do
+              table.insert(result, d.start_line, change_lines[i])
             end
           end
 
-          modified = vim.tbl_filter(function(line)
-            return line ~= nil
-          end, modified)
-
-          opts.text = table.concat(modified, '\n')
+          opts.text = table.concat(result, '\n')
         else
           opts.text = diff.change
         end
@@ -489,7 +505,7 @@ return {
           table.insert(lines, '')
         end
 
-        local selection = copilot.get_selection()
+        local selection = select.get(source.bufnr)
         if selection then
           table.insert(lines, '**Selection**')
           table.insert(lines, '')
@@ -519,7 +535,7 @@ return {
           end
 
           table.insert(lines, header)
-          table.insert(lines, '```' .. utils.mimetype_to_filetype(resource.mimetype))
+          table.insert(lines, '```' .. files.mimetype_to_filetype(resource.mimetype))
           for _, line in ipairs(preview) do
             table.insert(lines, line)
           end
diff --git a/lua/CopilotChat/config/prompts.lua b/lua/CopilotChat/config/prompts.lua
index 44b2f8bd..d40aee1f 100644
--- a/lua/CopilotChat/config/prompts.lua
+++ b/lua/CopilotChat/config/prompts.lua
@@ -1,5 +1,13 @@
-local COPILOT_BASE = [[
-When asked for your name, you must respond with "GitHub Copilot".
+---@class CopilotChat.config.prompts.Prompt : CopilotChat.config.Shared
+---@field prompt string?
+---@field description string?
+---@field mapping string?
+
+---@type table<string, CopilotChat.config.prompts.Prompt>
+return {
+  COPILOT_BASE = {
+    system_prompt = [[
+When asked for your name, you must respond with "Copilot".
 Follow the user's requirements carefully & to the letter.
 Keep your answers short and impersonal.
 Always answer in {LANGUAGE} unless explicitly asked otherwise.
@@ -13,74 +21,87 @@ The user works in editor called Neovim which has these core concepts:
 - Normal/Insert/Visual/Command modes: Different interaction states
 - LSP (Language Server Protocol): Provides code intelligence features like completion, diagnostics, and code actions
 - Treesitter: Provides syntax highlighting, code folding, and structural text editing based on syntax tree parsing
+- Visual selection: Text selected in visual mode that can be shared as context
 The user is working on a {OS_NAME} machine. Please respond with system specific commands if applicable.
 The user is currently in workspace directory {DIR} (typically the project root). Current file paths will be relative to this directory.
 </userEnvironment>
+<contextInstructions>
+Context is provided to you in several ways:
+- Resources: Contextual data shared via "# <uri>" headers and referenced via "##<uri>" links
+- Code blocks with file path labels and line numbers (e.g., ```lua path=/file.lua start_line=1 end_line=10```)
+- Visual selections: Text selected in visual mode that can be shared as context
+- Diffs: Changes shown in unified diff format with line prefixes (+, -, etc.)
+- Conversation history
+When resources (like buffers, files, or diffs) change, their content in the chat history is replaced with the latest version rather than appended as new data.
+</contextInstructions>
 <instructions>
 The user will ask a question or request a task that may require analysis to answer correctly.
 If you can infer the project type (languages, frameworks, libraries) from context, consider them when making changes.
 For implementing features, break down the request into concepts and provide a clear solution.
 Think creatively to provide complete solutions based on the information available.
-Never fabricate or hallucinate file contents you haven't actually seen.
+Never fabricate or hallucinate file contents you haven't actually seen in the provided context.
 </instructions>
 <toolUseInstructions>
-If tools are explicitly defined in your system prompt:
+If tools are available for a requested action (such as file edit, read, search, diagnostics, etc.), you MUST use the tool to perform the action. Only provide manual code or instructions if no tool exists for that purpose.
+- Always prefer tool usage over manual edits or suggestions.
 - Follow JSON schema precisely when using tools, including all required properties and outputting valid JSON.
-- Use appropriate tools for tasks rather than asking for manual actions.
+- Use appropriate tools for tasks rather than asking for manual actions or generating code for actions you can perform directly.
 - Execute actions directly when you indicate you'll do so, without asking for permission.
-- Only use tools that exist and use proper invocation procedures - no multi_tool_use.parallel.
-- Before using tools to retrieve information, check if it's already available in context:
-  1. Resources shared via "# <uri>" headers and referenced via "##<uri>" links
-  2. Code blocks with file path labels
-  3. Other contextual sharing like selected text or conversation history
-- If you don't have explicit tool definitions in your system prompt, assume NO tools are available and clearly state this limitation when asked. NEVER pretend to retrieve content you cannot access.
+- Only use tools that exist and use proper invocation procedures - no multi_tool_use.parallel unless specified.
+- Before using tools to retrieve information, check if context is already available as described in the context instructions above.
+- If you don't have explicit tool definitions in your system prompt, clearly state this limitation when asked. NEVER pretend to have tool capabilities you don't possess.
 </toolUseInstructions>
 <editFileInstructions>
-You will receive code snippets that include line number prefixes - use these to maintain correct position references but remove them when generating output.
-Always use code blocks to present code changes, even if the user doesn't ask for it.
+Use these instructions when editing files via code blocks. Your goal is to produce clear, minimal, and precise file edits.
 
-When presenting code changes:
+Steps for presenting code changes:
 1. For each change, use the following markdown code block format with triple backticks:
-  ```<filetype> path=<file_name> start_line=<start_line> end_line=<end_line>
-  <content>
-  ```
-
-  Examples:
-
-  ```lua path=lua/CopilotChat/init.lua start_line=40 end_line=50
-  local function example()
-    print("This is an example function.")
-  end
-  ```
-
-  ```python path=scripts/example.py start_line=10 end_line=15
-  def example_function():
-      print("This is an example function.")
-  ```
-
-  ```json path=config/settings.json start_line=5 end_line=8
-  {
-    "setting": "value",
-    "enabled": true
-  }
-  ```
-2. Keep changes minimal and focused to produce short diffs.
-3. Include complete replacement code for the specified line range with:
+   ```<filetype> path=<file_name> start_line=<start_line> end_line=<end_line>
+   <content>
+   ```
+
+2. Examples:
+   ```lua path=lua/CopilotChat/init.lua start_line=40 end_line=50
+   local function example()
+     print("This is an example function.")
+   end
+   ```
+
+   ```python path=scripts/example.py start_line=10 end_line=15
+   def example_function():
+       print("This is an example function.")
+   ```
+
+   ```json path=config/settings.json start_line=5 end_line=8
+   {
+     "setting": "value",
+     "enabled": true
+   }
+   ```
+
+3. Requirements for code content:
+   - Keep changes minimal and focused to produce short diffs
+   - Include complete replacement code for the specified line range
    - Proper indentation matching the source
    - All necessary lines (no eliding with comments)
-   - No line number prefixes in the code
-4. Address any diagnostics issues when fixing code.
-5. If multiple changes are needed, present them as separate code blocks.
+   - **Never include line number prefixes in your output code blocks. Only output valid code, exactly as it should appear in the file. Line numbers are only allowed in the code block header.**
+   - Address any diagnostics issues when fixing code
+
+4. If multiple changes are needed, present them as separate code blocks.
+
 </editFileInstructions>
-]]
+]],
+  },
 
-local COPILOT_INSTRUCTIONS = [[
+  COPILOT_INSTRUCTIONS = {
+    system_prompt = [[
 You are a code-focused AI programming assistant that specializes in practical software engineering solutions.
-]] .. COPILOT_BASE
+]],
+  },
 
-local COPILOT_EXPLAIN = [[
+  COPILOT_EXPLAIN = {
+    system_prompt = [[
 You are a programming instructor focused on clear, practical explanations.
-]] .. COPILOT_BASE .. [[
 
 When explaining code:
 - Provide concise high-level overview first
@@ -90,11 +111,12 @@ When explaining code:
 - Focus on complex parts rather than basic syntax
 - Use short paragraphs with clear structure
 - Mention performance considerations where relevant
-]]
+]],
+  },
 
-local COPILOT_REVIEW = [[
+  COPILOT_REVIEW = {
+    system_prompt = [[
 You are a code reviewer focused on improving code quality and maintainability.
-]] .. COPILOT_BASE .. [[
 
 Format each issue you find precisely as:
 line=<line_number>: <issue_description>
@@ -117,29 +139,7 @@ Multiple issues on one line should be separated by semicolons.
 End with: "**`To clear buffer highlights, please ask a different question.`**"
 
 If no issues found, confirm the code is well-written and explain why.
-]]
-
----@class CopilotChat.config.prompts.Prompt : CopilotChat.config.Shared
----@field prompt string?
----@field description string?
----@field mapping string?
-
----@type table<string, CopilotChat.config.prompts.Prompt>
-return {
-  COPILOT_BASE = {
-    system_prompt = COPILOT_BASE,
-  },
-
-  COPILOT_INSTRUCTIONS = {
-    system_prompt = COPILOT_INSTRUCTIONS,
-  },
-
-  COPILOT_EXPLAIN = {
-    system_prompt = COPILOT_EXPLAIN,
-  },
-
-  COPILOT_REVIEW = {
-    system_prompt = COPILOT_REVIEW,
+]],
   },
 
   Explain = {
@@ -152,7 +152,7 @@ return {
     system_prompt = 'COPILOT_REVIEW',
     callback = function(response, source)
       local diagnostics = {}
-      for line in response:gmatch('[^\r\n]+') do
+      for line in response.content:gmatch('[^\r\n]+') do
         if line:find('^line=') then
           local start_line = nil
           local end_line = nil
@@ -204,7 +204,10 @@ return {
   },
 
   Commit = {
-    prompt = 'Write commit message for the change with commitizen convention. Keep the title under 50 characters and wrap message at 72 characters. Format as a gitcommit code block.',
-    sticky = '#gitdiff:staged',
+    prompt = 'Write commit message for the change with commitizen convention. Keep the title under 50 characters and wrap message at 72 characters. Format as a gitcommit code block. If user has COMMIT_EDITMSG opened, generate replacement block for whole buffer.',
+    resources = {
+      'gitdiff:staged',
+      'buffer',
+    },
   },
 }
diff --git a/lua/CopilotChat/config/providers.lua b/lua/CopilotChat/config/providers.lua
index b2a03eea..f2f99b94 100644
--- a/lua/CopilotChat/config/providers.lua
+++ b/lua/CopilotChat/config/providers.lua
@@ -1,7 +1,9 @@
+local plenary_utils = require('plenary.async.util')
 local constants = require('CopilotChat.constants')
 local notify = require('CopilotChat.notify')
 local utils = require('CopilotChat.utils')
-local plenary_utils = require('plenary.async.util')
+local curl = require('CopilotChat.utils.curl')
+local files = require('CopilotChat.utils.files')
 
 local EDITOR_VERSION = 'Neovim/' .. vim.version().major .. '.' .. vim.version().minor .. '.' .. vim.version().patch
 
@@ -14,7 +16,7 @@ local function load_tokens()
 
   local config_path = vim.fs.normalize(vim.fn.stdpath('data') .. '/copilot_chat')
   local cache_file = config_path .. '/tokens.json'
-  local file = utils.read_file(cache_file)
+  local file = files.read_file(cache_file)
   if file then
     token_cache = vim.json.decode(file)
   else
@@ -42,7 +44,7 @@ local function set_token(tag, token, save)
   local tokens = load_tokens()
   tokens[tag] = token
   local config_path = vim.fs.normalize(vim.fn.stdpath('data') .. '/copilot_chat')
-  utils.write_file(config_path .. '/tokens.json', vim.json.encode(tokens))
+  files.write_file(config_path .. '/tokens.json', vim.json.encode(tokens))
   return token
 end
 
@@ -50,7 +52,7 @@ end
 ---@return string
 local function github_device_flow(tag, client_id, scope)
   local function request_device_code()
-    local res = utils.curl_post('https://github.com/login/device/code', {
+    local res = curl.post('https://github.com/login/device/code', {
       body = {
         client_id = client_id,
         scope = scope,
@@ -66,7 +68,7 @@ local function github_device_flow(tag, client_id, scope)
     while true do
       plenary_utils.sleep(interval * 1000)
 
-      local res = utils.curl_post('https://github.com/login/oauth/access_token', {
+      local res = curl.post('https://github.com/login/oauth/access_token', {
         body = {
           client_id = client_id,
           device_code = device_code,
@@ -141,7 +143,7 @@ local function get_github_copilot_token(tag)
     }
 
     for _, file_path in ipairs(file_paths) do
-      local file_data = utils.read_file(file_path)
+      local file_data = files.read_file(file_path)
       if file_data then
         local parsed_data = utils.json_decode(file_data)
         if parsed_data then
@@ -211,7 +213,7 @@ local M = {}
 
 M.copilot = {
   get_headers = function()
-    local response, err = utils.curl_get('https://api.github.com/copilot_internal/v2/token', {
+    local response, err = curl.get('https://api.github.com/copilot_internal/v2/token', {
       json_response = true,
       headers = {
         ['Authorization'] = 'Token ' .. get_github_copilot_token('github_copilot'),
@@ -231,8 +233,8 @@ M.copilot = {
       response.body.expires_at
   end,
 
-  get_info = function(headers)
-    local response, err = utils.curl_get('https://api.github.com/copilot_internal/user', {
+  get_info = function()
+    local response, err = curl.get('https://api.github.com/copilot_internal/user', {
       json_response = true,
       headers = {
         ['Authorization'] = 'Token ' .. get_github_copilot_token('github_copilot'),
@@ -282,7 +284,7 @@ M.copilot = {
   end,
 
   get_models = function(headers)
-    local response, err = utils.curl_get('https://api.githubcopilot.com/models', {
+    local response, err = curl.get('https://api.githubcopilot.com/models', {
       json_response = true,
       headers = headers,
     })
@@ -322,7 +324,7 @@ M.copilot = {
 
     for _, model in ipairs(models) do
       if not model.policy then
-        utils.curl_post('https://api.githubcopilot.com/models/' .. model.id .. '/policy', {
+        curl.post('https://api.githubcopilot.com/models/' .. model.id .. '/policy', {
           headers = headers,
           json_request = true,
           body = { state = 'enabled' },
@@ -462,7 +464,7 @@ M.github_models = {
   end,
 
   get_models = function(headers)
-    local response, err = utils.curl_get('https://models.github.ai/catalog/models', {
+    local response, err = curl.get('https://models.github.ai/catalog/models', {
       json_response = true,
       headers = headers,
     })
diff --git a/lua/CopilotChat/init.lua b/lua/CopilotChat/init.lua
index c97359dd..997b5d9f 100644
--- a/lua/CopilotChat/init.lua
+++ b/lua/CopilotChat/init.lua
@@ -4,7 +4,11 @@ local functions = require('CopilotChat.functions')
 local client = require('CopilotChat.client')
 local constants = require('CopilotChat.constants')
 local notify = require('CopilotChat.notify')
+local select = require('CopilotChat.select')
 local utils = require('CopilotChat.utils')
+local curl = require('CopilotChat.utils.curl')
+local orderedmap = require('CopilotChat.utils.orderedmap')
+local files = require('CopilotChat.utils.files')
 
 local WORD = '([^%s:]+)'
 local WORD_NO_INPUT = '([^%s]+)'
@@ -25,18 +29,22 @@ local M = setmetatable({}, {
 })
 
 --- @class CopilotChat.source
---- @field bufnr number
---- @field winnr number
+--- @field bufnr number?
+--- @field winnr number?
 --- @field cwd fun():string
 
 --- @class CopilotChat.state
 --- @field source CopilotChat.source?
 --- @field sticky string[]?
 local state = {
-  -- Current state tracking
-  source = nil,
+  source = {
+    bufnr = nil,
+    winnr = nil,
+    cwd = function()
+      return '.'
+    end,
+  },
 
-  -- Last state tracking
   sticky = nil,
 }
 
@@ -47,7 +55,7 @@ local function insert_sticky(prompt, config)
   local existing_prompt = M.chat:get_message(constants.ROLE.USER)
   local combined_prompt = (existing_prompt and existing_prompt.content or '') .. '\n' .. (prompt or '')
   local lines = vim.split(prompt or '', '\n')
-  local stickies = utils.ordered_map()
+  local stickies = orderedmap()
 
   local sticky_indices = {}
   local in_code_block = false
@@ -80,6 +88,12 @@ local function insert_sticky(prompt, config)
     end
   end
 
+  if config.remember_as_sticky and config.resources and not vim.deep_equal(config.resources, M.config.resources) then
+    for _, resource in ipairs(utils.to_table(config.resources)) do
+      stickies:set('#' .. resource, true)
+    end
+  end
+
   if
     config.remember_as_sticky
     and config.system_prompt
@@ -129,27 +143,6 @@ local function store_sticky(prompt)
   state.sticky = sticky
 end
 
---- Update the highlights for chat buffer
-local function update_highlights()
-  local selection_ns = vim.api.nvim_create_namespace('copilot-chat-selection')
-  for _, buf in ipairs(vim.api.nvim_list_bufs()) do
-    vim.api.nvim_buf_clear_namespace(buf, selection_ns, 0, -1)
-  end
-
-  if M.chat.config.highlight_selection and M.chat:focused() then
-    local selection = M.get_selection()
-    if not selection or not utils.buf_valid(selection.bufnr) or not selection.start_line or not selection.end_line then
-      return
-    end
-
-    vim.api.nvim_buf_set_extmark(selection.bufnr, selection_ns, selection.start_line - 1, 0, {
-      hl_group = 'CopilotChatSelection',
-      end_row = selection.end_line,
-      strict = false,
-    })
-  end
-end
-
 --- List available models.
 --- @return CopilotChat.client.Model[]
 local function list_models()
@@ -183,10 +176,6 @@ local function list_prompts()
       }
     end
 
-    if val.system_prompt and M.config.prompts[val.system_prompt] then
-      val.system_prompt = M.config.prompts[val.system_prompt].system_prompt
-    end
-
     prompts_to_use[name] = val
   end
 
@@ -319,10 +308,20 @@ function M.resolve_functions(prompt, config)
     tools[tool.name] = tool
   end
 
+  if config.resources then
+    local resources = utils.to_table(config.resources)
+    local lines = utils.split_lines(prompt)
+    for i = #resources, 1, -1 do
+      local resource = resources[i]
+      table.insert(lines, 1, '#' .. resource)
+    end
+    prompt = table.concat(lines, '\n')
+  end
+
   local enabled_tools = {}
   local resolved_resources = {}
   local resolved_tools = {}
-  local matches = utils.to_table(config.tools)
+  local tool_matches = utils.to_table(config.tools)
   local tool_calls = {}
   for _, message in ipairs(M.chat.messages) do
     if message.tool_calls then
@@ -336,13 +335,13 @@ function M.resolve_functions(prompt, config)
   prompt = prompt:gsub('@' .. WORD, function(match)
     for name, tool in pairs(M.config.functions) do
       if name == match or tool.group == match then
-        table.insert(matches, match)
+        table.insert(tool_matches, match)
         return ''
       end
     end
     return '@' .. match
   end)
-  for _, match in ipairs(matches) do
+  for _, match in ipairs(tool_matches) do
     for name, tool in pairs(M.config.functions) do
       if name == match or tool.group == match then
         table.insert(enabled_tools, tools[name])
@@ -350,12 +349,13 @@ function M.resolve_functions(prompt, config)
     end
   end
 
-  local matches = utils.ordered_map()
+  local resource_matches = {}
 
   -- Check for #word:`input` pattern
   for word, input in prompt:gmatch('#' .. WORD_WITH_INPUT_QUOTED) do
     local pattern = string.format('#%s:`%s`', word, input)
-    matches:set(pattern, {
+    table.insert(resource_matches, {
+      pattern = pattern,
       word = word,
       input = input,
     })
@@ -364,7 +364,8 @@ function M.resolve_functions(prompt, config)
   -- Check for #word:input pattern
   for word, input in prompt:gmatch('#' .. WORD_WITH_INPUT_UNQUOTED) do
     local pattern = utils.empty(input) and string.format('#%s', word) or string.format('#%s:%s', word, input)
-    matches:set(pattern, {
+    table.insert(resource_matches, {
+      pattern = pattern,
       word = word,
       input = input,
     })
@@ -373,7 +374,8 @@ function M.resolve_functions(prompt, config)
   -- Check for ##word:input pattern
   for word in prompt:gmatch('##' .. WORD_NO_INPUT) do
     local pattern = string.format('##%s', word)
-    matches:set(pattern, {
+    table.insert(resource_matches, {
+      pattern = pattern,
       word = word,
     })
   end
@@ -416,8 +418,15 @@ function M.resolve_functions(prompt, config)
     end
 
     local schema = tools[name] and tools[name].schema or nil
+    local ok, output
+    if config.stop_on_function_failure then
+      output = tool.resolve(functions.parse_input(input, schema), state.source)
+      ok = true
+    else
+      ok, output = pcall(tool.resolve, functions.parse_input(input, schema), state.source)
+    end
+
     local result = ''
-    local ok, output = pcall(tool.resolve, functions.parse_input(input, schema), state.source or {}, prompt)
     if not ok then
       result = string.format(BLOCK_OUTPUT_FORMAT, 'error', utils.make_string(output))
     else
@@ -425,19 +434,28 @@ function M.resolve_functions(prompt, config)
         if content then
           local content_out = nil
           if content.uri then
-            content_out = '##' .. content.uri
-            table.insert(resolved_resources, content)
+            if
+              not vim.tbl_contains(resolved_resources, function(resource)
+                return resource.uri == content.uri
+              end, { predicate = true })
+            then
+              content_out = '##' .. content.uri
+              table.insert(resolved_resources, content)
+            end
+
             if tool_id then
-              table.insert(state.sticky, content_out)
+              table.insert(state.sticky, '##' .. content.uri)
             end
           else
-            content_out = string.format(BLOCK_OUTPUT_FORMAT, utils.mimetype_to_filetype(content.mimetype), content.data)
+            content_out = string.format(BLOCK_OUTPUT_FORMAT, files.mimetype_to_filetype(content.mimetype), content.data)
           end
 
-          if not utils.empty(result) then
-            result = result .. '\n'
+          if content_out then
+            if not utils.empty(result) then
+              result = result .. '\n'
+            end
+            result = result .. content_out
           end
-          result = result .. content_out
         end
       end
     end
@@ -448,19 +466,21 @@ function M.resolve_functions(prompt, config)
         result = result,
       })
 
-      return nil
+      return ''
     end
 
     return result
   end
 
   -- Resolve and process all tools
-  for _, pattern in ipairs(matches:keys()) do
-    if not utils.empty(pattern) then
-      local match = matches:get(pattern)
-      local out = expand_function(match.word, match.input) or pattern
+  for _, match in ipairs(resource_matches) do
+    if not utils.empty(match.pattern) then
+      local out = expand_function(match.word, match.input)
+      if out == nil then
+        out = match.pattern
+      end
       out = out:gsub('%%', '%%%%') -- Escape percent signs for gsub
-      prompt = prompt:gsub(vim.pesc(pattern), out, 1)
+      prompt = prompt:gsub(vim.pesc(match.pattern), out, 1)
     end
   end
 
@@ -504,18 +524,34 @@ function M.resolve_prompt(prompt, config)
     return inner_config, inner_prompt
   end
 
+  local function resolve_system_prompt(system_prompt)
+    if type(system_prompt) == 'function' then
+      local ok, result = pcall(system_prompt)
+      if not ok then
+        log.warn('Failed to resolve system prompt function: ' .. result)
+        return nil
+      end
+      return result
+    end
+
+    return system_prompt
+  end
+
   config = vim.tbl_deep_extend('force', M.config, config or {})
   config, prompt = resolve(config, prompt or '')
-  if prompts_to_use[config.system_prompt] then
-    config.system_prompt = prompts_to_use[config.system_prompt].system_prompt
-  end
 
   if config.system_prompt then
+    config.system_prompt = resolve_system_prompt(config.system_prompt)
+
+    if M.config.prompts[config.system_prompt] then
+      -- Name references are good for making system prompt auto sticky
+      config.system_prompt = M.config.prompts[config.system_prompt].system_prompt
+    end
+
+    config.system_prompt = config.system_prompt .. '\n' .. M.config.prompts.COPILOT_BASE.system_prompt
     config.system_prompt = config.system_prompt:gsub('{OS_NAME}', jit.os)
     config.system_prompt = config.system_prompt:gsub('{LANGUAGE}', config.language)
-    if state.source then
-      config.system_prompt = config.system_prompt:gsub('{DIR}', state.source.cwd())
-    end
+    config.system_prompt = config.system_prompt:gsub('{DIR}', state.source.cwd())
   end
 
   return config, prompt
@@ -578,55 +614,6 @@ function M.set_source(source_winnr)
   return false
 end
 
---- Get the selection from the source buffer.
----@return CopilotChat.select.Selection?
-function M.get_selection()
-  local config = vim.tbl_deep_extend('force', M.config, M.chat.config)
-  local selection = config.selection
-  local bufnr = state.source and state.source.bufnr
-  local winnr = state.source and state.source.winnr
-
-  if selection and utils.buf_valid(bufnr) and winnr and vim.api.nvim_win_is_valid(winnr) then
-    return selection(state.source)
-  end
-
-  return nil
-end
-
---- Sets the selection to specific lines in buffer.
----@param bufnr number
----@param start_line number
----@param end_line number
----@param clear boolean?
-function M.set_selection(bufnr, start_line, end_line, clear)
-  if not utils.buf_valid(bufnr) then
-    return
-  end
-
-  if clear then
-    for _, mark in ipairs({ '<', '>', '[', ']' }) do
-      pcall(vim.api.nvim_buf_del_mark, bufnr, mark)
-    end
-    update_highlights()
-    return
-  end
-
-  local winnr = vim.fn.win_findbuf(bufnr)[1]
-  if not winnr and state.source then
-    winnr = state.source.winnr
-  end
-  if not winnr then
-    return
-  end
-
-  pcall(vim.api.nvim_buf_set_mark, bufnr, '<', start_line, 0, {})
-  pcall(vim.api.nvim_buf_set_mark, bufnr, '>', end_line, 0, {})
-  pcall(vim.api.nvim_buf_set_mark, bufnr, '[', start_line, 0, {})
-  pcall(vim.api.nvim_buf_set_mark, bufnr, ']', end_line, 0, {})
-  pcall(vim.api.nvim_win_set_cursor, winnr, { start_line, 0 })
-  update_highlights()
-end
-
 --- Open the chat window.
 ---@param config CopilotChat.config.Shared?
 function M.open(config)
@@ -653,7 +640,7 @@ end
 
 --- Close the chat window.
 function M.close()
-  M.chat:close(state.source and state.source.bufnr or nil)
+  M.chat:close(state.source.bufnr)
 end
 
 --- Toggle the chat window.
@@ -808,9 +795,6 @@ function M.ask(prompt, config)
       '\n'
     )
 
-    -- Retrieve the selection
-    local selection = M.get_selection()
-
     async.run(handle_error(config, function()
       local selected_tools, resolved_resources, resolved_tools, prompt = M.resolve_functions(prompt, config)
       local selected_model, prompt = M.resolve_model(prompt, config)
@@ -869,7 +853,6 @@ function M.ask(prompt, config)
       local ask_response = client.ask(client, prompt, {
         headless = config.headless,
         history = M.chat.messages,
-        selection = selection,
         resources = resolved_resources,
         tools = selected_tools,
         system_prompt = system_prompt,
@@ -894,7 +877,7 @@ function M.ask(prompt, config)
       -- Call the callback function
       if config.callback then
         utils.schedule_main()
-        config.callback(response.content, state.source)
+        config.callback(response, state.source)
       end
 
       if not config.headless then
@@ -923,11 +906,7 @@ function M.stop(reset)
   if reset then
     M.chat:clear()
     vim.diagnostic.reset(vim.api.nvim_create_namespace('copilot-chat-diagnostics'))
-
-    -- Clear the selection
-    if state.source then
-      M.set_selection(state.source.bufnr, 0, 0, true)
-    end
+    select.set(state.source.bufnr)
   end
 
   if stopped or reset then
@@ -1039,7 +1018,7 @@ function M.setup(config)
   end
 
   -- Save proxy and insecure settings
-  utils.curl_store_args({
+  curl.store_args({
     insecure = M.config.allow_insecure,
     proxy = M.config.proxy,
   })
@@ -1064,7 +1043,7 @@ function M.setup(config)
   end
 
   if M.chat then
-    M.chat:close(state.source and state.source.bufnr or nil)
+    M.chat:close(state.source.bufnr)
     M.chat:delete()
   end
   M.chat = require('CopilotChat.ui.chat')(M.config, function(bufnr)
@@ -1081,7 +1060,9 @@ function M.setup(config)
           update_source()
         end
 
-        vim.schedule(update_highlights)
+        vim.schedule(function()
+          select.highlight(state.source.bufnr, not (M.config.highlight_selection and M.chat:focused()))
+        end)
       end,
     })
 
diff --git a/lua/CopilotChat/resources.lua b/lua/CopilotChat/resources.lua
index a8c1fd78..57e12e33 100644
--- a/lua/CopilotChat/resources.lua
+++ b/lua/CopilotChat/resources.lua
@@ -1,5 +1,7 @@
 local async = require('plenary.async')
 local utils = require('CopilotChat.utils')
+local curl = require('CopilotChat.utils.curl')
+local files = require('CopilotChat.utils.files')
 local file_cache = {}
 local url_cache = {}
 
@@ -9,18 +11,19 @@ local M = {}
 ---@param filename string
 ---@return string?, string?
 function M.get_file(filename)
-  local filetype = utils.filetype(filename)
+  local filetype = files.filetype(filename)
   if not filetype then
     return nil
   end
-  local modified = utils.file_mtime(filename)
-  if not modified then
+  local err, stat = async.uv.fs_stat(filename)
+  if err or not stat then
     return nil
   end
+  local modified = stat.mtime.sec
 
   local data = file_cache[filename]
   if not data or data._modified < modified then
-    local content = utils.read_file(filename)
+    local content = files.read_file(filename)
     if not content or content == '' then
       return nil
     end
@@ -31,7 +34,7 @@ function M.get_file(filename)
     file_cache[filename] = data
   end
 
-  return data.content, utils.filetype_to_mimetype(filetype)
+  return data.content, files.filetype_to_mimetype(filetype)
 end
 
 --- Get data for a buffer
@@ -47,7 +50,7 @@ function M.get_buffer(bufnr)
     return nil
   end
 
-  return table.concat(content, '\n'), utils.filetype_to_mimetype(vim.bo[bufnr].filetype)
+  return table.concat(content, '\n'), files.filetype_to_mimetype(vim.bo[bufnr].filetype)
 end
 
 --- Get the content of an URL
@@ -58,7 +61,7 @@ function M.get_url(url)
     return nil
   end
 
-  local ft = utils.filetype(url)
+  local ft = files.filetype(url)
   local content = url_cache[url]
   if not content then
     local ok, out = async.util.apcall(utils.system, { 'lynx', '-dump', url })
@@ -67,7 +70,7 @@ function M.get_url(url)
       content = out.stdout
     else
       -- Fallback to curl if lynx fails
-      local response = utils.curl_get(url, { raw = { '-L' } })
+      local response = curl.get(url, { raw = { '-L' } })
       if not response or not response.body then
         return nil
       end
@@ -96,7 +99,7 @@ function M.get_url(url)
     url_cache[url] = content
   end
 
-  return content, utils.filetype_to_mimetype(ft)
+  return content, files.filetype_to_mimetype(ft)
 end
 
 return M
diff --git a/lua/CopilotChat/select.lua b/lua/CopilotChat/select.lua
index 8bef366c..425bf2a5 100644
--- a/lua/CopilotChat/select.lua
+++ b/lua/CopilotChat/select.lua
@@ -6,90 +6,86 @@
 ---@field filetype string
 ---@field bufnr number
 
+local log = require('plenary.log')
+local utils = require('CopilotChat.utils')
+
 local M = {}
 
---- Select and process current visual selection
---- @param source CopilotChat.source
---- @return CopilotChat.select.Selection|nil
-function M.visual(source)
-  local bufnr = source.bufnr
-  local start_line = unpack(vim.api.nvim_buf_get_mark(bufnr, '<'))
-  local finish_line = unpack(vim.api.nvim_buf_get_mark(bufnr, '>'))
-  if start_line == 0 or finish_line == 0 then
-    return nil
-  end
-  if start_line > finish_line then
-    start_line, finish_line = finish_line, start_line
-  end
+--- Use #selection instead
+---@deprecated
+function M.visual(_)
+  log.warn('CopilotChat.select.visual is deprecated, use #selection instead')
+  return nil
+end
 
-  local ok, lines = pcall(vim.api.nvim_buf_get_lines, bufnr, start_line - 1, finish_line, false)
-  if not ok then
-    return nil
+--- Use #selection instead
+---@deprecated use #selection instead
+function M.buffer(_)
+  log.warn('CopilotChat.select.buffer is deprecated, use #selection instead')
+  return nil
+end
+
+--- Use #selection instead
+---@deprecated use #selection instead
+function M.line(_)
+  log.warn('CopilotChat.select.line is deprecated, use #selection instead')
+  return nil
+end
+
+--- Use #selection instead
+---@deprecated use #selection instead
+function M.unnamed(_)
+  log.warn('CopilotChat.select.unnamed is deprecated, use #selection instead')
+  return nil
+end
+
+--- Get the marks used for selection
+---@return string[]
+function M.marks()
+  local config = require('CopilotChat.config')
+  local marks = { '<', '>' }
+  if config.selection == 'unnamed' then
+    marks = { '[', ']' }
   end
-  local lines_content = table.concat(lines, '\n')
-  if vim.trim(lines_content) == '' then
-    return nil
+  return marks
+end
+
+--- Highlight selection in target buffer or clear it
+---@param bufnr number
+---@param clear boolean?
+function M.highlight(bufnr, clear)
+  local selection_ns = vim.api.nvim_create_namespace('copilot-chat-selection')
+  for _, buf in ipairs(vim.api.nvim_list_bufs()) do
+    vim.api.nvim_buf_clear_namespace(buf, selection_ns, 0, -1)
   end
 
-  return {
-    content = lines_content,
-    filename = vim.api.nvim_buf_get_name(bufnr),
-    filetype = vim.bo[bufnr].filetype,
-    start_line = start_line,
-    end_line = finish_line,
-    bufnr = bufnr,
-  }
-end
+  if clear then
+    return
+  end
 
---- Select and process whole buffer
---- @param source CopilotChat.source
---- @return CopilotChat.select.Selection|nil
-function M.buffer(source)
-  local bufnr = source.bufnr
-  local lines = vim.api.nvim_buf_get_lines(bufnr, 0, -1, false)
-  if not lines or #lines == 0 then
-    return nil
+  local selection = M.get(bufnr)
+  if not selection then
+    return
   end
 
-  return {
-    content = table.concat(lines, '\n'),
-    filename = vim.api.nvim_buf_get_name(bufnr),
-    filetype = vim.bo[bufnr].filetype,
-    start_line = 1,
-    end_line = #lines,
-    bufnr = bufnr,
-  }
+  vim.api.nvim_buf_set_extmark(selection.bufnr, selection_ns, selection.start_line - 1, 0, {
+    hl_group = 'CopilotChatSelection',
+    end_row = selection.end_line,
+    strict = false,
+  })
 end
 
---- Select and process current line
---- @param source CopilotChat.source
---- @return CopilotChat.select.Selection|nil
-function M.line(source)
-  local bufnr = source.bufnr
-  local winnr = source.winnr
-  local cursor = vim.api.nvim_win_get_cursor(winnr)
-  local line = vim.api.nvim_buf_get_lines(bufnr, cursor[1] - 1, cursor[1], false)[1]
-  if not line then
+--- Get the selection from the target buffer
+---@param bufnr number
+---@return CopilotChat.select.Selection?
+function M.get(bufnr)
+  if not utils.buf_valid(bufnr) then
     return nil
   end
 
-  return {
-    content = line,
-    filename = vim.api.nvim_buf_get_name(bufnr),
-    filetype = vim.bo[bufnr].filetype,
-    start_line = cursor[1],
-    end_line = cursor[1],
-    bufnr = bufnr,
-  }
-end
-
---- Select and process contents of unnamed register ("). This register contains last deleted, changed or yanked content.
---- @param source CopilotChat.source
---- @return CopilotChat.select.Selection|nil
-function M.unnamed(source)
-  local bufnr = source.bufnr
-  local start_line = unpack(vim.api.nvim_buf_get_mark(bufnr, '['))
-  local finish_line = unpack(vim.api.nvim_buf_get_mark(bufnr, ']'))
+  local marks = M.marks()
+  local start_line = unpack(vim.api.nvim_buf_get_mark(bufnr, marks[1]))
+  local finish_line = unpack(vim.api.nvim_buf_get_mark(bufnr, marks[2]))
   if start_line == 0 or finish_line == 0 then
     return nil
   end
@@ -116,4 +112,31 @@ function M.unnamed(source)
   }
 end
 
+--- Sets the selection to specific lines in buffer or clears it
+---@param bufnr number
+---@param winnr number?
+---@param start_line number?
+---@param end_line number?
+function M.set(bufnr, winnr, start_line, end_line)
+  if not utils.buf_valid(bufnr) then
+    return
+  end
+
+  local marks = M.marks()
+
+  if not start_line or not end_line then
+    for _, mark in ipairs(marks) do
+      pcall(vim.api.nvim_buf_del_mark, bufnr, mark)
+    end
+    return
+  end
+
+  pcall(vim.api.nvim_buf_set_mark, bufnr, marks[1], start_line, 0, {})
+  pcall(vim.api.nvim_buf_set_mark, bufnr, marks[2], end_line, 0, {})
+
+  if winnr and vim.api.nvim_win_is_valid(winnr) then
+    pcall(vim.api.nvim_win_set_cursor, winnr, { start_line, 0 })
+  end
+end
+
 return M
diff --git a/lua/CopilotChat/tiktoken.lua b/lua/CopilotChat/tiktoken.lua
index 3f631428..4066388a 100644
--- a/lua/CopilotChat/tiktoken.lua
+++ b/lua/CopilotChat/tiktoken.lua
@@ -1,6 +1,7 @@
 local notify = require('CopilotChat.notify')
 local utils = require('CopilotChat.utils')
-local class = utils.class
+local curl = require('CopilotChat.utils.curl')
+local class = require('CopilotChat.utils.class')
 
 --- Get the library extension based on the operating system
 --- @return string
@@ -30,7 +31,7 @@ local function load_tiktoken_data(tokenizer)
 
   notify.publish(notify.STATUS, 'Downloading tiktoken data from ' .. tiktoken_url)
 
-  utils.curl_get(tiktoken_url, {
+  curl.get(tiktoken_url, {
     output = cache_path,
   })
 
diff --git a/lua/CopilotChat/ui/chat.lua b/lua/CopilotChat/ui/chat.lua
index e7f0c75c..d6c1e283 100644
--- a/lua/CopilotChat/ui/chat.lua
+++ b/lua/CopilotChat/ui/chat.lua
@@ -3,7 +3,7 @@ local Spinner = require('CopilotChat.ui.spinner')
 local constants = require('CopilotChat.constants')
 local notify = require('CopilotChat.notify')
 local utils = require('CopilotChat.utils')
-local class = utils.class
+local class = require('CopilotChat.utils.class')
 
 function CopilotChatFoldExpr(lnum, separator)
   local to_match = separator .. '$'
@@ -736,7 +736,7 @@ function Chat:render()
   -- Replace self.messages with new_messages (preserving tool_calls, etc.)
   self.messages = new_messages
 
-  for _, message in ipairs(self.messages) do
+  for i, message in ipairs(self.messages) do
     -- Show tool call details as virt lines
     if message.tool_calls and #message.tool_calls > 0 then
       local section = message.section
@@ -790,6 +790,17 @@ function Chat:render()
         strict = false,
       })
     end
+
+    if self.config.auto_fold and self:visible() then
+      if message.role ~= constants.ROLE.ASSISTANT and message.section and i < #self.messages then
+        vim.api.nvim_win_call(self.winnr, function()
+          local fold_level = vim.fn.foldlevel(message.section.start_line)
+          if fold_level > 0 and vim.fn.foldclosed(message.section.start_line) == -1 then
+            vim.api.nvim_cmd({ cmd = 'foldclose', range = { message.section.start_line } }, {})
+          end
+        end)
+      end
+    end
   end
 
   -- Show help as before, using last user message
diff --git a/lua/CopilotChat/ui/overlay.lua b/lua/CopilotChat/ui/overlay.lua
index a23c022e..298bfcb2 100644
--- a/lua/CopilotChat/ui/overlay.lua
+++ b/lua/CopilotChat/ui/overlay.lua
@@ -1,5 +1,5 @@
 local utils = require('CopilotChat.utils')
-local class = utils.class
+local class = require('CopilotChat.utils.class')
 
 ---@class CopilotChat.ui.overlay.Overlay : Class
 ---@field bufnr number?
diff --git a/lua/CopilotChat/ui/spinner.lua b/lua/CopilotChat/ui/spinner.lua
index 0f582032..44c77b80 100644
--- a/lua/CopilotChat/ui/spinner.lua
+++ b/lua/CopilotChat/ui/spinner.lua
@@ -1,6 +1,7 @@
 local notify = require('CopilotChat.notify')
 local utils = require('CopilotChat.utils')
-local class = utils.class
+local class = require('CopilotChat.utils.class')
+
 local spinner_frames = {
   '⠋',
   '⠙',
diff --git a/lua/CopilotChat/utils.lua b/lua/CopilotChat/utils.lua
index fe2f4773..8b32a85b 100644
--- a/lua/CopilotChat/utils.lua
+++ b/lua/CopilotChat/utils.lua
@@ -1,107 +1,21 @@
 local async = require('plenary.async')
-local curl = require('plenary.curl')
-local scandir = require('plenary.scandir')
 local log = require('plenary.log')
 
 local M = {}
 M.timers = {}
 
-M.scan_args = {
-  max_count = 2500,
-  max_depth = 50,
-  no_ignore = false,
-}
-
-M.curl_args = {
-  timeout = 30000,
-  raw = {
-    '--retry',
-    '2',
-    '--retry-delay',
-    '1',
-    '--keepalive-time',
-    '60',
-    '--no-compressed',
-    '--connect-timeout',
-    '10',
-    '--tcp-nodelay',
-    '--no-buffer',
-  },
-}
-
----@class Class
----@field new fun(...):table
----@field init fun(self, ...)
-
---- Create class
----@param fn function The class constructor
----@param parent table? The parent class
----@return Class
-function M.class(fn, parent)
-  local out = {}
-  out.__index = out
-
-  local mt = {
-    __call = function(cls, ...)
-      return cls.new(...)
-    end,
-  }
-
-  if parent then
-    mt.__index = parent
-  end
-
-  setmetatable(out, mt)
-
-  function out.new(...)
-    local self = setmetatable({}, out)
-    fn(self, ...)
-    return self
-  end
-
-  function out.init(self, ...)
-    fn(self, ...)
-  end
-
-  return out
+--- Use CopilotChat.utils.curl.get instead
+---@deprecated
+function M.curl_get(url, opts)
+  log.warn('M.curl_get is deprecated, use CopilotChat.utils.curl.get instead')
+  return require('CopilotChat.utils.curl').get(url, opts)
 end
 
----@class OrderedMap<K, V>
----@field set fun(self:OrderedMap, key:any, value:any)
----@field get fun(self:OrderedMap, key:any):any
----@field keys fun(self:OrderedMap):table
----@field values fun(self:OrderedMap):table
-
---- Create an ordered map
----@generic K, V
----@return OrderedMap<K, V>
-function M.ordered_map()
-  return {
-    _keys = {},
-    _data = {},
-    set = function(self, key, value)
-      if not self._data[key] then
-        table.insert(self._keys, key)
-      end
-      self._data[key] = value
-    end,
-
-    get = function(self, key)
-      return self._data[key]
-    end,
-
-    keys = function(self)
-      return self._keys
-    end,
-
-    values = function(self)
-      local result = {}
-      for _, key in ipairs(self._keys) do
-        table.insert(result, self._data[key])
-      end
-      return result
-    end,
-  }
+--- Use CopilotChat.utils.curl.post instead
+---@deprecated
+function M.curl_post(url, opts)
+  log.warn('M.curl_post is deprecated, use CopilotChat.utils.curl.post instead')
+  return require('CopilotChat.utils.curl').post(url, opts)
 end
 
 --- Convert arguments to a table
@@ -122,61 +36,13 @@ function M.to_table(...)
   return result
 end
 
----@class StringBuffer
----@field add fun(self:StringBuffer, s:string)
----@field set fun(self:StringBuffer, s:string)
----@field tostring fun(self:StringBuffer):string
-
---- Create a string buffer for efficient string concatenation
----@return StringBuffer
-function M.string_buffer()
-  return {
-    _buf = { '' },
-
-    add = function(self, s)
-      table.insert(self._buf, s)
-      -- Keep track of lengths to know when to merge
-      for i = #self._buf - 1, 1, -1 do
-        if #self._buf[i] > #self._buf[i + 1] then
-          break
-        end
-        self._buf[i] = self._buf[i] .. table.remove(self._buf)
-      end
-    end,
-
-    set = function(self, s)
-      self._buf = { s }
-    end,
-
-    -- Get final string
-    tostring = function(self)
-      return table.concat(self._buf)
-    end,
-  }
-end
-
---- Writes text to a temporary file and returns path
----@param text string The text to write
----@return string?
-function M.temp_file(text)
-  local temp_file = os.tmpname()
-  local f = io.open(temp_file, 'w+')
-  if f == nil then
-    error('Could not open file: ' .. temp_file)
-  end
-  f:write(text)
-  f:close()
-  return temp_file
-end
-
 --- Return to normal mode
 function M.return_to_normal_mode()
   local mode = vim.fn.mode():lower()
   if mode:find('v') then
     vim.cmd([[execute "normal! \<Esc>"]])
-  elseif mode ~= 'n' then
-    vim.cmd('stopinsert')
   end
+  vim.cmd('stopinsert')
 end
 
 --- Debounce a function
@@ -200,91 +66,6 @@ function M.buf_valid(bufnr)
     or false
 end
 
---- Check if file paths are the same
----@param file1 string? The first file path
----@param file2 string? The second file path
----@return boolean
-function M.filename_same(file1, file2)
-  if not file1 or not file2 then
-    return false
-  end
-  return vim.fn.fnamemodify(file1, ':p') == vim.fn.fnamemodify(file2, ':p')
-end
-
---- Get the filetype of a file
----@param filename string The file name
----@return string|nil
-function M.filetype(filename)
-  local filetype = require('plenary.filetype')
-
-  local ft = filetype.detect(filename, {
-    fs_access = false,
-  })
-
-  if ft == '' or not ft then
-    return vim.filetype.match({ filename = filename })
-  end
-
-  return ft
-end
-
---- Get the mimetype from filetype
----@param filetype string?
----@return string
-function M.filetype_to_mimetype(filetype)
-  if not filetype or filetype == '' then
-    return 'text/plain'
-  end
-  if filetype == 'json' or filetype == 'yaml' then
-    return 'application/' .. filetype
-  end
-  if filetype == 'html' or filetype == 'css' then
-    return 'text/' .. filetype
-  end
-  if filetype:find('/') then
-    return filetype
-  end
-  return 'text/x-' .. filetype
-end
-
---- Get the filetype from mimetype
----@param mimetype string?
----@return string
-function M.mimetype_to_filetype(mimetype)
-  if not mimetype or mimetype == '' then
-    return 'text'
-  end
-
-  local out = mimetype:gsub('^text/x%-', '')
-  out = out:gsub('^text/', '')
-  out = out:gsub('^application/', '')
-  out = out:gsub('^image/', '')
-  out = out:gsub('^video/', '')
-  out = out:gsub('^audio/', '')
-  return out
-end
-
---- Convert a URI to a file name
----@param uri string The URI
----@return string
-function M.uri_to_filename(uri)
-  if not uri or uri == '' then
-    return uri
-  end
-  local ok, fname = pcall(vim.uri_to_fname, uri)
-  if not ok or M.empty(fname) then
-    return uri
-  end
-  return fname
-end
-
---- Get the file name
----@param filepath string The file path
----@return string
-function M.filename(filepath)
-  return vim.fs.basename(filepath)
-end
-
 --- Generate a UUID
 ---@return string
 function M.uuid()
@@ -341,325 +122,6 @@ function M.json_decode(body)
   return {}, data
 end
 
---- Store curl global arguments
----@param args table The arguments
----@return table
-function M.curl_store_args(args)
-  M.curl_args = vim.tbl_deep_extend('force', M.curl_args, args)
-  return M.curl_args
-end
-
---- Send curl get request
----@param url string The url
----@param opts table? The options
----@async
-M.curl_get = async.wrap(function(url, opts, callback)
-  log.debug('GET request:', url, opts)
-  local args = {
-    on_error = function(err)
-      log.debug('GET error:', err)
-      callback(nil, err and err.stderr or err)
-    end,
-  }
-
-  args = vim.tbl_deep_extend('force', M.curl_args, args)
-  args = vim.tbl_deep_extend('force', args, opts or {})
-
-  args.callback = function(response)
-    log.debug('GET response:', response)
-    if response and not vim.startswith(tostring(response.status), '20') then
-      callback(response, response.body)
-      return
-    end
-
-    if not args.json_response then
-      callback(response)
-      return
-    end
-
-    local body, err = M.json_decode(tostring(response.body))
-    if err then
-      callback(response, err)
-    else
-      response.body = body
-      callback(response)
-    end
-  end
-
-  curl.get(url, args)
-end, 3)
-
---- Send curl post request
----@param url string The url
----@param opts table? The options
----@async
-M.curl_post = async.wrap(function(url, opts, callback)
-  log.debug('POST request:', url, opts)
-  local args = {
-    on_error = function(err)
-      log.debug('POST error:', err)
-      callback(nil, err and err.stderr or err)
-    end,
-  }
-
-  args = vim.tbl_deep_extend('force', M.curl_args, args)
-  args = vim.tbl_deep_extend('force', args, opts or {})
-
-  local temp_file_path = nil
-
-  args.callback = function(response)
-    log.debug('POST response:', url, response)
-    if temp_file_path then
-      local ok, err = pcall(os.remove, temp_file_path)
-      if not ok then
-        log.debug('Failed to remove temp file:', temp_file_path, err)
-      end
-    end
-    if response and not vim.startswith(tostring(response.status), '20') then
-      callback(response, response.body)
-      return
-    end
-
-    if not args.json_response then
-      callback(response)
-      return
-    end
-
-    local body, err = M.json_decode(tostring(response.body))
-    if err then
-      callback(response, err)
-    else
-      response.body = body
-      callback(response)
-    end
-  end
-
-  if args.json_response then
-    args.headers = vim.tbl_deep_extend('force', args.headers or {}, {
-      Accept = 'application/json',
-    })
-  end
-
-  if args.json_request then
-    args.headers = vim.tbl_deep_extend('force', args.headers or {}, {
-      ['Content-Type'] = 'application/json',
-    })
-
-    temp_file_path = M.temp_file(vim.json.encode(args.body))
-    args.body = temp_file_path
-  end
-
-  curl.post(url, args)
-end, 3)
-
-local function filter_files(files, max_count)
-  local filetype = require('plenary.filetype')
-
-  files = vim.tbl_filter(function(file)
-    if file == nil or file == '' then
-      return false
-    end
-
-    local ft = filetype.detect(file, {
-      fs_access = false,
-    })
-
-    if ft == '' or not ft then
-      return false
-    end
-
-    return true
-  end, files)
-  if max_count and max_count > 0 then
-    files = vim.list_slice(files, 1, max_count)
-  end
-
-  return files
-end
-
----@class CopilotChat.utils.ScanOpts
----@field max_count number? The maximum number of files to scan
----@field max_depth number? The maximum depth to scan
----@field glob? string The glob pattern to match files
----@field hidden? boolean Whether to include hidden files
----@field no_ignore? boolean Whether to respect or ignore .gitignore
-
---- Scan a directory
----@param path string
----@param opts CopilotChat.utils.ScanOpts?
----@async
-M.glob = async.wrap(function(path, opts, callback)
-  opts = vim.tbl_deep_extend('force', M.scan_args, opts or {})
-
-  -- Use ripgrep if available
-  if vim.fn.executable('rg') == 1 then
-    local cmd = { 'rg' }
-
-    if opts.pattern then
-      table.insert(cmd, '-g')
-      table.insert(cmd, opts.pattern)
-    end
-
-    if opts.max_depth then
-      table.insert(cmd, '--max-depth')
-      table.insert(cmd, tostring(opts.max_depth))
-    end
-
-    if opts.no_ignore then
-      table.insert(cmd, '--no-ignore')
-    end
-
-    if opts.hidden then
-      table.insert(cmd, '--hidden')
-    end
-
-    table.insert(cmd, '--files')
-    table.insert(cmd, path)
-
-    vim.system(cmd, { text = true }, function(result)
-      local files = {}
-      if result and result.code == 0 and result.stdout ~= '' then
-        files = filter_files(vim.split(result.stdout, '\n'), opts.max_count)
-      end
-
-      callback(files)
-    end)
-
-    return
-  end
-
-  -- Fall back to scandir if rg is not available or fails
-  scandir.scan_dir_async(
-    path,
-    vim.tbl_deep_extend('force', opts, {
-      depth = opts.max_depth,
-      add_dirs = false,
-      search_pattern = opts.glob and M.glob_to_pattern(opts.glob) or nil,
-      respect_gitignore = not opts.no_ignore,
-      on_exit = function(files)
-        callback(filter_files(files, opts.max_count))
-      end,
-    })
-  )
-end, 3)
-
---- Grep a directory
----@param path string The path to search
----@param opts CopilotChat.utils.ScanOpts?
-M.grep = async.wrap(function(path, opts, callback)
-  opts = vim.tbl_deep_extend('force', M.scan_args, opts or {})
-  local cmd = {}
-
-  if vim.fn.executable('rg') == 1 then
-    table.insert(cmd, 'rg')
-
-    if opts.max_depth then
-      table.insert(cmd, '--max-depth')
-      table.insert(cmd, tostring(opts.max_depth))
-    end
-
-    if opts.no_ignore then
-      table.insert(cmd, '--no-ignore')
-    end
-
-    if opts.hidden then
-      table.insert(cmd, '--hidden')
-    end
-
-    table.insert(cmd, '--files-with-matches')
-    table.insert(cmd, '--ignore-case')
-
-    if opts.pattern then
-      table.insert(cmd, '-e')
-      table.insert(cmd, "'" .. opts.pattern .. "'")
-    end
-
-    table.insert(cmd, path)
-  elseif vim.fn.executable('grep') == 1 then
-    table.insert(cmd, 'grep')
-    table.insert(cmd, '-rli')
-
-    if opts.pattern then
-      table.insert(cmd, '-e')
-      table.insert(cmd, "'" .. opts.pattern .. "'")
-    end
-
-    table.insert(cmd, path)
-  end
-
-  if M.empty(cmd) then
-    error('No executable found for grep')
-    return
-  end
-
-  vim.system(cmd, { text = true }, function(result)
-    local files = {}
-    if result and result.code == 0 and result.stdout ~= '' then
-      files = filter_files(vim.split(result.stdout, '\n'), opts.max_count)
-    end
-
-    callback(files)
-  end)
-end, 3)
-
---- Get last modified time of a file
----@param path string The file path
----@return number?
----@async
-function M.file_mtime(path)
-  local err, stat = async.uv.fs_stat(path)
-  if err or not stat then
-    return nil
-  end
-  return stat.mtime.sec
-end
-
---- Read a file
----@param path string The file path
----@async
-function M.read_file(path)
-  local err, fd = async.uv.fs_open(path, 'r', 438)
-  if err or not fd then
-    return nil
-  end
-
-  local err, stat = async.uv.fs_fstat(fd)
-  if err or not stat then
-    async.uv.fs_close(fd)
-    return nil
-  end
-
-  local err, data = async.uv.fs_read(fd, stat.size, 0)
-  async.uv.fs_close(fd)
-  if err or not data then
-    return nil
-  end
-  return data
-end
-
---- Write data to a file
----@param path string The file path
----@param data string The data to write
----@return boolean
-function M.write_file(path, data)
-  M.schedule_main()
-  vim.fn.mkdir(vim.fn.fnamemodify(path, ':p:h'), 'p')
-
-  local err, fd = async.uv.fs_open(path, 'w', 438)
-  if err or not fd then
-    return false
-  end
-
-  local err = async.uv.fs_write(fd, data, 0)
-  if err then
-    async.uv.fs_close(fd)
-    return false
-  end
-
-  async.uv.fs_close(fd)
-  return true
-end
-
 --- Call a system command
 ---@param cmd table The command
 ---@async
@@ -773,136 +235,15 @@ function M.empty(v)
   return false
 end
 
---- Convert glob pattern to regex pattern
---- https://github.com/davidm/lua-glob-pattern/blob/master/lua/globtopattern.lua
----@param g string The glob pattern
----@return string
-function M.glob_to_pattern(g)
-  local p = '^' -- pattern being built
-  local i = 0 -- index in g
-  local c -- char at index i in g.
-
-  -- unescape glob char
-  local function unescape()
-    if c == '\\' then
-      i = i + 1
-      c = g:sub(i, i)
-      if c == '' then
-        p = '[^]'
-        return false
-      end
-    end
-    return true
+--- Split text into lines
+---@param text string The text to split
+---@return string[] A table of lines
+function M.split_lines(text)
+  if not text or text == '' then
+    return {}
   end
 
-  -- escape pattern char
-  local function escape(c)
-    return c:match('^%w$') and c or '%' .. c
-  end
-
-  -- Convert tokens at end of charset.
-  local function charset_end()
-    while 1 do
-      if c == '' then
-        p = '[^]'
-        return false
-      elseif c == ']' then
-        p = p .. ']'
-        break
-      else
-        if not unescape() then
-          break
-        end
-        local c1 = c
-        i = i + 1
-        c = g:sub(i, i)
-        if c == '' then
-          p = '[^]'
-          return false
-        elseif c == '-' then
-          i = i + 1
-          c = g:sub(i, i)
-          if c == '' then
-            p = '[^]'
-            return false
-          elseif c == ']' then
-            p = p .. escape(c1) .. '%-]'
-            break
-          else
-            if not unescape() then
-              break
-            end
-            p = p .. escape(c1) .. '-' .. escape(c)
-          end
-        elseif c == ']' then
-          p = p .. escape(c1) .. ']'
-          break
-        else
-          p = p .. escape(c1)
-          i = i - 1 -- put back
-        end
-      end
-      i = i + 1
-      c = g:sub(i, i)
-    end
-    return true
-  end
-
-  -- Convert tokens in charset.
-  local function charset()
-    i = i + 1
-    c = g:sub(i, i)
-    if c == '' or c == ']' then
-      p = '[^]'
-      return false
-    elseif c == '^' or c == '!' then
-      i = i + 1
-      c = g:sub(i, i)
-      if c == ']' then
-        -- ignored
-      else
-        p = p .. '[^'
-        if not charset_end() then
-          return false
-        end
-      end
-    else
-      p = p .. '['
-      if not charset_end() then
-        return false
-      end
-    end
-    return true
-  end
-
-  -- Convert tokens.
-  while 1 do
-    i = i + 1
-    c = g:sub(i, i)
-    if c == '' then
-      p = p .. '$'
-      break
-    elseif c == '?' then
-      p = p .. '.'
-    elseif c == '*' then
-      p = p .. '.*'
-    elseif c == '[' then
-      if not charset() then
-        break
-      end
-    elseif c == '\\' then
-      i = i + 1
-      c = g:sub(i, i)
-      if c == '' then
-        p = p .. '\\$'
-        break
-      end
-      p = p .. escape(c)
-    else
-      p = p .. escape(c)
-    end
-  end
-  return p
+  return vim.split(text, '\r?\n', { trimempty = false })
 end
 
 return M
diff --git a/lua/CopilotChat/utils/class.lua b/lua/CopilotChat/utils/class.lua
new file mode 100644
index 00000000..b8dfce83
--- /dev/null
+++ b/lua/CopilotChat/utils/class.lua
@@ -0,0 +1,38 @@
+---@class Class
+---@field new fun(...):table
+---@field init fun(self, ...)
+
+--- Create class
+---@param fn function The class constructor
+---@param parent table? The parent class
+---@return Class
+local function class(fn, parent)
+  local out = {}
+  out.__index = out
+
+  local mt = {
+    __call = function(cls, ...)
+      return cls.new(...)
+    end,
+  }
+
+  if parent then
+    mt.__index = parent
+  end
+
+  setmetatable(out, mt)
+
+  function out.new(...)
+    local self = setmetatable({}, out)
+    fn(self, ...)
+    return self
+  end
+
+  function out.init(self, ...)
+    fn(self, ...)
+  end
+
+  return out
+end
+
+return class
diff --git a/lua/CopilotChat/utils/curl.lua b/lua/CopilotChat/utils/curl.lua
new file mode 100644
index 00000000..87e9b89d
--- /dev/null
+++ b/lua/CopilotChat/utils/curl.lua
@@ -0,0 +1,142 @@
+local async = require('plenary.async')
+local curl = require('plenary.curl')
+local log = require('plenary.log')
+local utils = require('CopilotChat.utils')
+
+local M = {}
+
+M.args = {
+  timeout = 30000,
+  raw = {
+    '--retry',
+    '2',
+    '--retry-delay',
+    '1',
+    '--keepalive-time',
+    '60',
+    '--no-compressed',
+    '--connect-timeout',
+    '10',
+    '--tcp-nodelay',
+    '--no-buffer',
+  },
+}
+
+--- Store curl global arguments
+---@param args table The arguments
+---@return table
+function M.store_args(args)
+  M.args = vim.tbl_deep_extend('force', M.args, args)
+  return M.args
+end
+
+--- Send curl get request
+---@param url string The url
+---@param opts table? The options
+---@async
+M.get = async.wrap(function(url, opts, callback)
+  log.debug('GET request:', url, opts)
+  local args = {
+    on_error = function(err)
+      log.debug('GET error:', err)
+      callback(nil, err and err.stderr or err)
+    end,
+  }
+
+  args = vim.tbl_deep_extend('force', M.args, args)
+  args = vim.tbl_deep_extend('force', args, opts or {})
+
+  args.callback = function(response)
+    log.debug('GET response:', response)
+    if response and not vim.startswith(tostring(response.status), '20') then
+      callback(response, response.body)
+      return
+    end
+
+    if not args.json_response then
+      callback(response)
+      return
+    end
+
+    local body, err = utils.json_decode(tostring(response.body))
+    if err then
+      callback(response, err)
+    else
+      response.body = body
+      callback(response)
+    end
+  end
+
+  curl.get(url, args)
+end, 3)
+
+--- Send curl post request
+---@param url string The url
+---@param opts table? The options
+---@async
+M.post = async.wrap(function(url, opts, callback)
+  log.debug('POST request:', url, opts)
+  local args = {
+    on_error = function(err)
+      log.debug('POST error:', err)
+      callback(nil, err and err.stderr or err)
+    end,
+  }
+
+  args = vim.tbl_deep_extend('force', M.args, args)
+  args = vim.tbl_deep_extend('force', args, opts or {})
+
+  local temp_file_path = nil
+
+  args.callback = function(response)
+    log.debug('POST response:', url, response)
+    if temp_file_path then
+      local ok, err = pcall(os.remove, temp_file_path)
+      if not ok then
+        log.debug('Failed to remove temp file:', temp_file_path, err)
+      end
+    end
+    if response and not vim.startswith(tostring(response.status), '20') then
+      callback(response, response.body)
+      return
+    end
+
+    if not args.json_response then
+      callback(response)
+      return
+    end
+
+    local body, err = utils.json_decode(tostring(response.body))
+    if err then
+      callback(response, err)
+    else
+      response.body = body
+      callback(response)
+    end
+  end
+
+  if args.json_response then
+    args.headers = vim.tbl_deep_extend('force', args.headers or {}, {
+      Accept = 'application/json',
+    })
+  end
+
+  if args.json_request then
+    args.headers = vim.tbl_deep_extend('force', args.headers or {}, {
+      ['Content-Type'] = 'application/json',
+    })
+
+    temp_file_path = os.tmpname()
+    local f = io.open(temp_file_path, 'w+')
+    if f == nil then
+      error('Could not open file: ' .. temp_file_path)
+    end
+    f:write(vim.json.encode(args.body))
+    f:close()
+    args.body = temp_file_path
+  end
+
+  curl.post(url, args)
+end, 3)
+
+return M
diff --git a/lua/CopilotChat/utils/files.lua b/lua/CopilotChat/utils/files.lua
new file mode 100644
index 00000000..683ccd14
--- /dev/null
+++ b/lua/CopilotChat/utils/files.lua
@@ -0,0 +1,330 @@
+local async = require('plenary.async')
+
+local M = {}
+
+M.scan_args = {
+  max_count = 2500,
+  max_depth = 50,
+  no_ignore = false,
+}
+
+local function filter_files(files, max_count)
+  local filetype = require('plenary.filetype')
+
+  files = vim.tbl_filter(function(file)
+    if file == nil or file == '' then
+      return false
+    end
+
+    local ft = filetype.detect(file, {
+      fs_access = false,
+    })
+
+    if ft == '' or not ft then
+      return false
+    end
+
+    return true
+  end, files)
+  if max_count and max_count > 0 then
+    files = vim.list_slice(files, 1, max_count)
+  end
+
+  return files
+end
+
+---@class CopilotChat.utils.ScanOpts
+---@field max_count number? The maximum number of files to scan
+---@field max_depth number? The maximum depth to scan
+---@field pattern? string The glob pattern to match files
+---@field hidden? boolean Whether to include hidden files
+---@field no_ignore? boolean Whether to respect or ignore .gitignore
+
+--- Scan a directory
+---@param path string
+---@param opts CopilotChat.utils.ScanOpts?
+---@async
+M.glob = async.wrap(function(path, opts, callback)
+  opts = vim.tbl_deep_extend('force', M.scan_args, opts or {})
+
+  -- Use ripgrep if available
+  if vim.fn.executable('rg') == 1 then
+    local cmd = { 'rg' }
+
+    if opts.pattern then
+      table.insert(cmd, '-g')
+      table.insert(cmd, opts.pattern)
+    end
+
+    if opts.max_depth then
+      table.insert(cmd, '--max-depth')
+      table.insert(cmd, tostring(opts.max_depth))
+    end
+
+    if opts.no_ignore then
+      table.insert(cmd, '--no-ignore')
+    end
+
+    if opts.hidden then
+      table.insert(cmd, '--hidden')
+    end
+
+    table.insert(cmd, '--files')
+
+    vim.system(cmd, { cwd = path, text = true }, function(result)
+      local files = {}
+      if result and result.code == 0 and result.stdout ~= '' then
+        files = filter_files(vim.split(result.stdout, '\n'), opts.max_count)
+      end
+
+      callback(files)
+    end)
+
+    return
+  end
+
+  -- Fallback to vim.uv.fs_scandir
+  local matchers = {}
+  if opts.pattern then
+    local file_pattern = vim.glob.to_lpeg(opts.pattern)
+    local path_pattern = vim.lpeg.P(path .. '/') * file_pattern
+
+    table.insert(matchers, function(name, dir)
+      return file_pattern:match(name) or path_pattern:match(dir .. '/' .. name)
+    end)
+  end
+
+  if not opts.hidden then
+    table.insert(matchers, function(name)
+      return not name:match('^%.')
+    end)
+  end
+
+  local data = {}
+  local next_dir = { path }
+  local current_depths = { [path] = 1 }
+
+  local function read_dir(err, fd)
+    local current_dir = table.remove(next_dir, 1)
+    local depth = current_depths[current_dir] or 1
+
+    if not err and fd then
+      while true do
+        local name, typ = vim.uv.fs_scandir_next(fd)
+        if name == nil then
+          break
+        end
+
+        local full_path = current_dir .. '/' .. name
+
+        if typ == 'directory' and not name:match('^%.git') then
+          if not opts.max_depth or depth < opts.max_depth then
+            table.insert(next_dir, full_path)
+            current_depths[full_path] = depth + 1
+          end
+        else
+          local match = true
+          for _, matcher in ipairs(matchers) do
+            if not matcher(name, current_dir) then
+              match = false
+              break
+            end
+          end
+
+          if match then
+            table.insert(data, full_path)
+          end
+        end
+      end
+    end
+
+    if #next_dir == 0 then
+      callback(data)
+    else
+      vim.uv.fs_scandir(next_dir[1], read_dir)
+    end
+  end
+
+  vim.uv.fs_scandir(path, read_dir)
+end, 3)
+
+--- Grep a directory
+---@param path string The path to search
+---@param opts CopilotChat.utils.ScanOpts?
+M.grep = async.wrap(function(path, opts, callback)
+  opts = vim.tbl_deep_extend('force', M.scan_args, opts or {})
+  local cmd = {}
+
+  if vim.fn.executable('rg') == 1 then
+    table.insert(cmd, 'rg')
+
+    if opts.max_depth then
+      table.insert(cmd, '--max-depth')
+      table.insert(cmd, tostring(opts.max_depth))
+    end
+
+    if opts.no_ignore then
+      table.insert(cmd, '--no-ignore')
+    end
+
+    if opts.hidden then
+      table.insert(cmd, '--hidden')
+    end
+
+    table.insert(cmd, '--files-with-matches')
+    table.insert(cmd, '--ignore-case')
+
+    if opts.pattern then
+      table.insert(cmd, '-e')
+      table.insert(cmd, "'" .. opts.pattern .. "'")
+    end
+  elseif vim.fn.executable('grep') == 1 then
+    table.insert(cmd, 'grep')
+    table.insert(cmd, '-rli')
+
+    if opts.pattern then
+      table.insert(cmd, '-e')
+      table.insert(cmd, "'" .. opts.pattern .. "'")
+    end
+  end
+
+  if M.empty(cmd) then
+    error('No executable found for grep')
+    return
+  end
+
+  vim.system(cmd, { cwd = path, text = true }, function(result)
+    local files = {}
+    if result and result.code == 0 and result.stdout ~= '' then
+      files = filter_files(vim.split(result.stdout, '\n'), opts.max_count)
+    end
+
+    callback(files)
+  end)
+end, 3)
+
+--- Read a file
+---@param path string The file path
+---@async
+function M.read_file(path)
+  local err, fd = async.uv.fs_open(path, 'r', 438)
+  if err or not fd then
+    return nil
+  end
+
+  local err, stat = async.uv.fs_fstat(fd)
+  if err or not stat then
+    async.uv.fs_close(fd)
+    return nil
+  end
+
+  local err, data = async.uv.fs_read(fd, stat.size, 0)
+  async.uv.fs_close(fd)
+  if err or not data then
+    return nil
+  end
+  return data
+end
+
+--- Write data to a file
+---@param path string The file path
+---@param data string The data to write
+---@return boolean
+function M.write_file(path, data)
+  M.schedule_main()
+  vim.fn.mkdir(vim.fn.fnamemodify(path, ':p:h'), 'p')
+
+  local err, fd = async.uv.fs_open(path, 'w', 438)
+  if err or not fd then
+    return false
+  end
+
+  local err = async.uv.fs_write(fd, data, 0)
+  if err then
+    async.uv.fs_close(fd)
+    return false
+  end
+
+  async.uv.fs_close(fd)
+  return true
+end
+
+--- Check if file paths are the same
+---@param file1 string? The first file path
+---@param file2 string? The second file path
+---@return boolean
+function M.filename_same(file1, file2)
+  if not file1 or not file2 then
+    return false
+  end
+  return vim.fn.fnamemodify(file1, ':p') == vim.fn.fnamemodify(file2, ':p')
+end
+
+--- Get the filetype of a file
+---@param filename string The file name
+---@return string|nil
+function M.filetype(filename)
+  local filetype = require('plenary.filetype')
+
+  local ft = filetype.detect(filename, {
+    fs_access = false,
+  })
+
+  if ft == '' or not ft and not vim.in_fast_event() then
+    return vim.filetype.match({ filename = filename })
+  end
+
+  return ft
+end
+
+--- Get the mimetype from filetype
+---@param filetype string?
+---@return string
+function M.filetype_to_mimetype(filetype)
+  if not filetype or filetype == '' then
+    return 'text/plain'
+  end
+  if filetype == 'json' or filetype == 'yaml' then
+    return 'application/' .. filetype
+  end
+  if filetype == 'html' or filetype == 'css' then
+    return 'text/' .. filetype
+  end
+  if filetype:find('/') then
+    return filetype
+  end
+  return 'text/x-' .. filetype
+end
+
+--- Get the filetype from mimetype
+---@param mimetype string?
+---@return string
+function M.mimetype_to_filetype(mimetype)
+  if not mimetype or mimetype == '' then
+    return 'text'
+  end
+
+  local out = mimetype:gsub('^text/x%-', '')
+  out = out:gsub('^text/', '')
+  out = out:gsub('^application/', '')
+  out = out:gsub('^image/', '')
+  out = out:gsub('^video/', '')
+  out = out:gsub('^audio/', '')
+  return out
+end
+
+--- Convert a URI to a file name
+---@param uri string The URI
+---@return string
+function M.uri_to_filename(uri)
+  if not uri or uri == '' then
+    return uri
+  end
+  local ok, fname = pcall(vim.uri_to_fname, uri)
+  if not ok or M.empty(fname) then
+    return uri
+  end
+  return fname
+end
+
+return M
diff --git a/lua/CopilotChat/utils/orderedmap.lua b/lua/CopilotChat/utils/orderedmap.lua
new file mode 100644
index 00000000..778c686d
--- /dev/null
+++ b/lua/CopilotChat/utils/orderedmap.lua
@@ -0,0 +1,39 @@
+---@class OrderedMap<K, V>
+---@field set fun(self:OrderedMap, key:any, value:any)
+---@field get fun(self:OrderedMap, key:any):any
+---@field keys fun(self:OrderedMap):table
+---@field values fun(self:OrderedMap):table
+
+--- Create ordered map
+---@generic K, V
+---@return OrderedMap<K, V>
+local function orderedmap()
+  return {
+    _keys = {},
+    _data = {},
+    set = function(self, key, value)
+      if not self._data[key] then
+        table.insert(self._keys, key)
+      end
+      self._data[key] = value
+    end,
+
+    get = function(self, key)
+      return self._data[key]
+    end,
+
+    keys = function(self)
+      return self._keys
+    end,
+
+    values = function(self)
+      local result = {}
+      for _, key in ipairs(self._keys) do
+        table.insert(result, self._data[key])
+      end
+      return result
+    end,
+  }
+end
+
+return orderedmap
diff --git a/lua/CopilotChat/utils/stringbuffer.lua b/lua/CopilotChat/utils/stringbuffer.lua
new file mode 100644
index 00000000..de89f2db
--- /dev/null
+++ b/lua/CopilotChat/utils/stringbuffer.lua
@@ -0,0 +1,46 @@
+local ok, jit_buffer = pcall(require, 'string.buffer')
+
+---@class StringBuffer
+---@field put fun(self:StringBuffer, s:string)
+---@field set fun(self:StringBuffer, s:string)
+---@field tostring fun(self:StringBuffer):string
+
+--- Create a string buffer for efficient string concatenation
+---@return StringBuffer
+local function stringbuffer()
+  if ok and jit_buffer then
+    return {
+      _buf = jit_buffer.new(),
+      put = function(self, s)
+        self._buf:put(s)
+      end,
+      set = function(self, s)
+        self._buf:set(s)
+      end,
+      tostring = function(self)
+        return self._buf:tostring()
+      end,
+    }
+  end
+
+  return {
+    _buf = { '' },
+    put = function(self, s)
+      table.insert(self._buf, s)
+      for i = #self._buf - 1, 1, -1 do
+        if #self._buf[i] > #self._buf[i + 1] then
+          break
+        end
+        self._buf[i] = self._buf[i] .. table.remove(self._buf)
+      end
+    end,
+    set = function(self, s)
+      self._buf = { s }
+    end,
+    tostring = function(self)
+      return table.concat(self._buf)
+    end,
+  }
+end
+
+return stringbuffer
diff --git a/plugin/CopilotChat.lua b/plugin/CopilotChat.lua
index e59ee49e..db83d5b2 100644
--- a/plugin/CopilotChat.lua
+++ b/plugin/CopilotChat.lua
@@ -14,6 +14,7 @@ local group = vim.api.nvim_create_augroup('CopilotChat', {})
 local function setup_highlights()
   vim.api.nvim_set_hl(0, 'CopilotChatHeader', { link = '@markup.heading.2.markdown', default = true })
   vim.api.nvim_set_hl(0, 'CopilotChatSeparator', { link = '@punctuation.special.markdown', default = true })
+  vim.api.nvim_set_hl(0, 'CopilotChatSelection', { link = 'Visual', default = true })
   vim.api.nvim_set_hl(0, 'CopilotChatStatus', { link = 'DiagnosticHint', default = true })
   vim.api.nvim_set_hl(0, 'CopilotChatHelp', { link = 'DiagnosticInfo', default = true })
   vim.api.nvim_set_hl(0, 'CopilotChatResource', { link = 'Constant', default = true })
@@ -21,7 +22,6 @@ local function setup_highlights()
   vim.api.nvim_set_hl(0, 'CopilotChatPrompt', { link = 'Statement', default = true })
   vim.api.nvim_set_hl(0, 'CopilotChatModel', { link = 'Type', default = true })
   vim.api.nvim_set_hl(0, 'CopilotChatUri', { link = 'Underlined', default = true })
-  vim.api.nvim_set_hl(0, 'CopilotChatSelection', { link = 'Visual', default = true })
 
   vim.api.nvim_set_hl(0, 'CopilotChatAnnotation', { link = 'ColorColumn', default = true })
   local fg = vim.api.nvim_get_hl(0, { name = 'CopilotChatStatus', link = false }).fg
@@ -36,6 +36,18 @@ vim.api.nvim_create_autocmd('ColorScheme', {
 })
 setup_highlights()
 
+vim.api.nvim_create_autocmd('FileType', {
+  pattern = 'copilot-chat',
+  group = group,
+  callback = vim.schedule_wrap(function()
+    vim.cmd.syntax('match CopilotChatResource "#\\S\\+"')
+    vim.cmd.syntax('match CopilotChatTool "@\\S\\+"')
+    vim.cmd.syntax('match CopilotChatPrompt "/\\S\\+"')
+    vim.cmd.syntax('match CopilotChatModel "\\$\\S\\+"')
+    vim.cmd.syntax('match CopilotChatUri "##\\S\\+"')
+  end),
+})
+
 -- Setup commands
 vim.api.nvim_create_user_command('CopilotChat', function(args)
   local chat = require('CopilotChat')
@@ -79,18 +91,6 @@ vim.api.nvim_create_user_command('CopilotChatReset', function()
   chat.reset()
 end, { force = true })
 
-vim.api.nvim_create_autocmd('FileType', {
-  pattern = 'copilot-chat',
-  group = group,
-  callback = vim.schedule_wrap(function()
-    vim.cmd.syntax('match CopilotChatResource "#\\S\\+"')
-    vim.cmd.syntax('match CopilotChatTool "@\\S\\+"')
-    vim.cmd.syntax('match CopilotChatPrompt "/\\S\\+"')
-    vim.cmd.syntax('match CopilotChatModel "\\$\\S\\+"')
-    vim.cmd.syntax('match CopilotChatUri "##\\S\\+"')
-  end),
-})
-
 local function complete_load()
   local chat = require('CopilotChat')
   local options = vim.tbl_map(function(file)
diff --git a/scripts/minimal.lua b/scripts/minimal.lua
new file mode 100644
index 00000000..69c5cefb
--- /dev/null
+++ b/scripts/minimal.lua
@@ -0,0 +1,16 @@
+-- https://github.com/neovim/neovim/blob/master/contrib/minimal.lua
+vim.opt.runtimepath:append(vim.fn.getcwd())
+
+for name, url in pairs({
+  'https://github.com/nvim-lua/plenary.nvim',
+}) do
+  local install_path = vim.fn.fnamemodify('.dependencies/' .. name, ':p')
+  if vim.fn.isdirectory(install_path) == 0 then
+    vim.fn.system({ 'git', 'clone', '--depth=1', url, install_path })
+  end
+  vim.opt.runtimepath:append(install_path)
+end
+
+require('CopilotChat').setup({
+  -- Add your configuration here
+})
diff --git a/scripts/test.lua b/scripts/test.lua
new file mode 100644
index 00000000..5da43da3
--- /dev/null
+++ b/scripts/test.lua
@@ -0,0 +1,13 @@
+vim.opt.runtimepath:append(vim.fn.getcwd())
+
+for name, url in pairs({
+  'https://github.com/nvim-lua/plenary.nvim',
+}) do
+  local install_path = vim.fn.fnamemodify('.dependencies/' .. name, ':p')
+  if vim.fn.isdirectory(install_path) == 0 then
+    vim.fn.system({ 'git', 'clone', '--depth=1', url, install_path })
+  end
+  vim.opt.runtimepath:append(install_path)
+end
+
+require('plenary.test_harness').test_directory('tests')
diff --git a/test/plugin_spec.lua b/test/plugin_spec.lua
deleted file mode 100644
index 9497f016..00000000
--- a/test/plugin_spec.lua
+++ /dev/null
@@ -1,18 +0,0 @@
--- Mock packages
-package.loaded['plenary.async'] = {
-  wrap = function(fn)
-    return function(...)
-      return fn(...)
-    end
-  end,
-}
-package.loaded['plenary.curl'] = {}
-package.loaded['plenary.log'] = {}
-package.loaded['plenary.scandir'] = {}
-package.loaded['plenary.filetype'] = {}
-
-describe('CopilotChat plugin', function()
-  it('should be able to load', function()
-    assert.truthy(require('CopilotChat'))
-  end)
-end)
diff --git a/tests/class_spec.lua b/tests/class_spec.lua
new file mode 100644
index 00000000..ef2f1657
--- /dev/null
+++ b/tests/class_spec.lua
@@ -0,0 +1,33 @@
+local class = require('CopilotChat.utils.class')
+
+describe('CopilotChat.utils.class', function()
+  it('creates a simple class', function()
+    local Foo = class(function(self, x)
+      self.x = x
+    end)
+    local obj = Foo(42)
+    assert.equals(42, obj.x)
+  end)
+
+  it('supports init method', function()
+    local Bar = class(function(self, y)
+      self.y = y
+    end)
+    local obj = Bar.new(7)
+    assert.equals(7, obj.y)
+    obj:init(8)
+    assert.equals(8, obj.y)
+  end)
+
+  it('supports inheritance', function()
+    local Parent = class(function(self)
+      self.val = 1
+    end)
+    local Child = class(function(self)
+      self.val = 2
+    end, Parent)
+    local obj = Child()
+    assert.equals(2, obj.val)
+    assert.equals(Parent, getmetatable(Child).__index)
+  end)
+end)
diff --git a/tests/functions_spec.lua b/tests/functions_spec.lua
new file mode 100644
index 00000000..93939cdb
--- /dev/null
+++ b/tests/functions_spec.lua
@@ -0,0 +1,62 @@
+local functions = require('CopilotChat.functions')
+
+describe('CopilotChat.functions', function()
+  describe('uri_to_url', function()
+    it('replaces parameters in uri template', function()
+      local uri = 'file://{path}'
+      local input = { path = '/tmp/test.txt' }
+      assert.equals('file:///tmp/test.txt', functions.uri_to_url(uri, input))
+    end)
+    it('leaves missing params empty', function()
+      local uri = 'file://{path}/{id}'
+      local input = { path = '/tmp' }
+      assert.equals('file:///tmp/', functions.uri_to_url(uri, input))
+    end)
+  end)
+
+  describe('match_uri', function()
+    it('matches uri and extracts parameters', function()
+      local uri = 'file:///tmp/test.txt'
+      local pattern = 'file://{path}'
+      local result = functions.match_uri(uri, pattern)
+      assert.are.same({ path = '/tmp/test.txt' }, result)
+    end)
+    it('returns nil for non-matching uri', function()
+      assert.is_nil(functions.match_uri('abc', 'file://{path}'))
+    end)
+    it('returns empty table for exact match with no params', function()
+      assert.are.same({}, functions.match_uri('abc', 'abc'))
+    end)
+  end)
+
+  describe('parse_schema', function()
+    it('returns schema if present', function()
+      local fn = { schema = { type = 'object', properties = { foo = { type = 'string' } } } }
+      assert.equals(fn.schema, functions.parse_schema(fn))
+    end)
+    it('generates schema from uri if missing', function()
+      local fn = { uri = 'file://{path}/{id}' }
+      local schema = functions.parse_schema(fn)
+      assert.are.same({
+        type = 'object',
+        properties = { path = { type = 'string' }, id = { type = 'string' } },
+        required = { 'path', 'id' },
+      }, schema)
+    end)
+  end)
+
+  describe('parse_input', function()
+    it('parses input string into table', function()
+      local schema = { properties = { a = {}, b = {} }, required = { 'a', 'b' } }
+      local input = 'foo;;bar'
+      assert.are.same({ a = 'foo', b = 'bar' }, functions.parse_input(input, schema))
+    end)
+    it('returns input if already table', function()
+      local input = { a = 1 }
+      assert.equals(input, functions.parse_input(input))
+    end)
+    it('returns empty table if no schema', function()
+      assert.are.same({}, functions.parse_input('foo'))
+    end)
+  end)
+end)
diff --git a/tests/init_spec.lua b/tests/init_spec.lua
new file mode 100644
index 00000000..995a84c3
--- /dev/null
+++ b/tests/init_spec.lua
@@ -0,0 +1,14 @@
+describe('CopilotChat module', function()
+  it('should be able to load', function()
+    assert.has_no.errors(function()
+      require('CopilotChat')
+    end)
+  end)
+
+  it('should be able to set up', function()
+    assert.has_no.errors(function()
+      require('CopilotChat').setup({})
+    end)
+    assert.is_not_nil(require('CopilotChat').chat)
+  end)
+end)
diff --git a/tests/orderedmap_spec.lua b/tests/orderedmap_spec.lua
new file mode 100644
index 00000000..9000915c
--- /dev/null
+++ b/tests/orderedmap_spec.lua
@@ -0,0 +1,28 @@
+local orderedmap = require('CopilotChat.utils.orderedmap')
+
+describe('CopilotChat.utils.orderedmap', function()
+  it('sets and gets values', function()
+    local map = orderedmap()
+    map:set('a', 1)
+    map:set('b', 2)
+    assert.equals(1, map:get('a'))
+    assert.equals(2, map:get('b'))
+  end)
+
+  it('preserves insertion order', function()
+    local map = orderedmap()
+    map:set('x', 10)
+    map:set('y', 20)
+    map:set('z', 30)
+    assert.are.same({ 'x', 'y', 'z' }, map:keys())
+    assert.are.same({ 10, 20, 30 }, map:values())
+  end)
+
+  it('overwrites value but not order', function()
+    local map = orderedmap()
+    map:set('a', 1)
+    map:set('a', 2)
+    assert.are.same({ 'a' }, map:keys())
+    assert.are.same({ 2 }, map:values())
+  end)
+end)
diff --git a/tests/stringbuffer_spec.lua b/tests/stringbuffer_spec.lua
new file mode 100644
index 00000000..d491fd43
--- /dev/null
+++ b/tests/stringbuffer_spec.lua
@@ -0,0 +1,23 @@
+local stringbuffer = require('CopilotChat.utils.stringbuffer')
+
+describe('CopilotChat.utils.stringbuffer', function()
+  it('concatenates strings with put', function()
+    local buf = stringbuffer()
+    buf:put('hello')
+    buf:put(' ')
+    buf:put('world')
+    assert.equals('hello world', buf:tostring())
+  end)
+
+  it('sets buffer with set', function()
+    local buf = stringbuffer()
+    buf:put('foo')
+    buf:set('bar')
+    assert.equals('bar', buf:tostring())
+  end)
+
+  it('handles empty buffer', function()
+    local buf = stringbuffer()
+    assert.equals('', buf:tostring())
+  end)
+end)
diff --git a/tests/utils_spec.lua b/tests/utils_spec.lua
new file mode 100644
index 00000000..5352395d
--- /dev/null
+++ b/tests/utils_spec.lua
@@ -0,0 +1,40 @@
+local utils = require('CopilotChat.utils')
+
+describe('CopilotChat.utils', function()
+  it('empty', function()
+    assert.is_true(utils.empty(nil))
+    assert.is_true(utils.empty(''))
+    assert.is_true(utils.empty('   '))
+    assert.is_true(utils.empty({}))
+    assert.is_false(utils.empty({ 1 }))
+    assert.is_false(utils.empty('abc'))
+    assert.is_false(utils.empty(0))
+  end)
+
+  it('split_lines', function()
+    assert.are.same(utils.split_lines(''), {})
+    assert.are.same(utils.split_lines('a\nb'), { 'a', 'b' })
+    assert.are.same(utils.split_lines('a\r\nb'), { 'a', 'b' })
+    assert.are.same(utils.split_lines('a\nb\n'), { 'a', 'b', '' })
+  end)
+
+  it('make_string', function()
+    assert.equals('a b 1', utils.make_string('a', 'b', 1))
+    assert.equals(vim.inspect({ x = 1 }), utils.make_string({ x = 1 }))
+    assert.equals('msg', utils.make_string('error:1: msg'))
+  end)
+
+  it('uuid', function()
+    local uuid1 = utils.uuid()
+    local uuid2 = utils.uuid()
+    assert.equals('string', type(uuid1))
+    assert.not_equals(uuid1, uuid2)
+    assert.equals(36, #uuid1)
+  end)
+
+  it('to_table', function()
+    assert.are.same({ 1, 2, 3 }, utils.to_table(1, 2, 3))
+    assert.are.same({ 1, 2, 3 }, utils.to_table({ 1, 2 }, 3))
+    assert.are.same({ 1 }, utils.to_table(nil, 1))
+  end)
+end)
diff --git a/version.txt b/version.txt
index cca25a93..a84947d6 100644
--- a/version.txt
+++ b/version.txt
@@ -1 +1 @@
-4.4.1
+4.5.0