Merge pull request 'Update Cargo.toml' (#14) from nvrl-patch-1 into main

Reviewed-on: #14

.gitea/workflows/release.yaml

@@ -36,10 +36,6 @@ jobs:
         id: check_release
         shell: bash
         run: |
-          # Use curl to check if a release for the current TAG already exists on Gitea
-          # This prevents the workflow from failing if a push to main doesn't update the version
-          # Assuming standard Gitea API (e.g., https://gitea.example.com/api/v1/repos/{owner}/{repo}/releases/tags/{tag})
-          # github.repository is usually 'owner/repo'
           HTTP_STATUS=$(curl -s -o /dev/null -w "%{http_code}" \
             -H "Authorization: token ${{ secrets.GITHUB_TOKEN }}" \
             "${{ github.server_url }}/api/v1/repos/${{ github.repository }}/releases/tags/${{ steps.get_version.outputs.TAG }}")
@@ -53,31 +49,22 @@ jobs:
 
       - name: Build
         if: steps.check_release.outputs.EXISTS == 'false'
-        run: cargo build --release
+        run: |
+          cargo build --release
+          mv target/release/mould target/release/mould-${{ steps.get_version.outputs.TAG }}-linux-amd64
 
-      - name: Create Release
+      - name: Create Release and Upload Asset
         if: steps.check_release.outputs.EXISTS == 'false'
-        id: create_release
+        uses: https://github.com/softprops/action-gh-release@v1
-        uses: https://github.com/actions/create-release@v1
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
         with:
           tag_name: ${{ steps.get_version.outputs.TAG }}
-          release_name: Release ${{ steps.get_version.outputs.TAG }}
+          name: Release ${{ steps.get_version.outputs.TAG }}
           body: |
             Automated release for version ${{ steps.get_version.outputs.VERSION }}
             Commit: ${{ github.sha }}
             Branch: ${{ github.ref_name }}
+          files: target/release/mould-${{ steps.get_version.outputs.TAG }}-linux-amd64
           draft: false
           prerelease: false
-
-      - name: Upload Release Asset
-        if: steps.check_release.outputs.EXISTS == 'false'
-        uses: https://github.com/actions/upload-release-asset@v1
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-        with:
-          upload_url: ${{ steps.create_release.outputs.upload_url }}
-          asset_path: ./target/release/cenv
-          asset_name: cenv-${{ steps.get_version.outputs.TAG }}-linux-amd64
-          asset_content_type: application/octet-stream

Cargo.lock

@@ -17,6 +17,80 @@ version = "0.2.21"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "683d7910e743518b0e34f1186f92494becacb047c7b6bf616c96772180fef923"
 
+[[package]]
+name = "anstream"
+version = "0.6.21"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "43d5b281e737544384e969a5ccad3f1cdd24b48086a0fc1b2a5262a26b8f4f4a"
+dependencies = [
+ "anstyle",
+ "anstyle-parse 0.2.7",
+ "anstyle-query",
+ "anstyle-wincon",
+ "colorchoice",
+ "is_terminal_polyfill",
+ "utf8parse",
+]
+
+[[package]]
+name = "anstream"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "824a212faf96e9acacdbd09febd34438f8f711fb84e09a8916013cd7815ca28d"
+dependencies = [
+ "anstyle",
+ "anstyle-parse 1.0.0",
+ "anstyle-query",
+ "anstyle-wincon",
+ "colorchoice",
+ "is_terminal_polyfill",
+ "utf8parse",
+]
+
+[[package]]
+name = "anstyle"
+version = "1.0.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "940b3a0ca603d1eade50a4846a2afffd5ef57a9feac2c0e2ec2e14f9ead76000"
+
+[[package]]
+name = "anstyle-parse"
+version = "0.2.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4e7644824f0aa2c7b9384579234ef10eb7efb6a0deb83f9630a49594dd9c15c2"
+dependencies = [
+ "utf8parse",
+]
+
+[[package]]
+name = "anstyle-parse"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "52ce7f38b242319f7cabaa6813055467063ecdc9d355bbb4ce0c68908cd8130e"
+dependencies = [
+ "utf8parse",
+]
+
+[[package]]
+name = "anstyle-query"
+version = "1.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "40c48f72fd53cd289104fc64099abca73db4166ad86ea0b4341abe65af83dadc"
+dependencies = [
+ "windows-sys",
+]
+
+[[package]]
+name = "anstyle-wincon"
+version = "3.0.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "291e6a250ff86cd4a820112fb8898808a366d8f9f58ce16d1f538353ad55747d"
+dependencies = [
+ "anstyle",
+ "once_cell_polyfill",
+ "windows-sys",
+]
+
 [[package]]
 name = "anyhow"
 version = "1.0.102"
@@ -101,18 +175,6 @@ dependencies = [
  "rustversion",
 ]
 
-[[package]]
-name = "cenv-rs"
-version = "0.1.0"
-dependencies = [
- "crossterm",
- "dirs",
- "ratatui",
- "serde",
- "tempfile",
- "toml",
-]
-
 [[package]]
 name = "cfg-if"
 version = "1.0.4"
@@ -125,6 +187,52 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "613afe47fcd5fac7ccf1db93babcb082c5994d996f20b8b159f2ad1658eb5724"
 
+[[package]]
+name = "clap"
+version = "4.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b193af5b67834b676abd72466a96c1024e6a6ad978a1f484bd90b85c94041351"
+dependencies = [
+ "clap_builder",
+ "clap_derive",
+]
+
+[[package]]
+name = "clap_builder"
+version = "4.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "714a53001bf66416adb0e2ef5ac857140e7dc3a0c48fb28b2f10762fc4b5069f"
+dependencies = [
+ "anstream 1.0.0",
+ "anstyle",
+ "clap_lex",
+ "strsim",
+]
+
+[[package]]
+name = "clap_derive"
+version = "4.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1110bd8a634a1ab8cb04345d8d878267d57c3cf1b38d91b71af6686408bbca6a"
+dependencies = [
+ "heck",
+ "proc-macro2",
+ "quote",
+ "syn 2.0.117",
+]
+
+[[package]]
+name = "clap_lex"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c8d4a3bb8b1e0c1050499d1815f5ab16d04f0959b233085fb31653fbfc9d98f9"
+
+[[package]]
+name = "colorchoice"
+version = "1.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1d07550c9036bf2ae0c684c4297d503f838287c83c53686d05370d0e139ae570"
+
 [[package]]
 name = "compact_str"
 version = "0.9.0"
@@ -321,6 +429,29 @@ version = "1.15.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "48c757948c5ede0e46177b7add2e67155f70e33c07fea8284df6576da70b3719"
 
+[[package]]
+name = "env_filter"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7a1c3cc8e57274ec99de65301228b537f1e4eedc1b8e0f9411c6caac8ae7308f"
+dependencies = [
+ "log",
+ "regex",
+]
+
+[[package]]
+name = "env_logger"
+version = "0.11.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b2daee4ea451f429a58296525ddf28b45a3b64f1acf6587e2067437bb11e218d"
+dependencies = [
+ "anstream 0.6.21",
+ "anstyle",
+ "env_filter",
+ "jiff",
+ "log",
+]
+
 [[package]]
 name = "equivalent"
 version = "1.0.2"
@@ -527,6 +658,12 @@ dependencies = [
  "syn 2.0.117",
 ]
 
+[[package]]
+name = "is_terminal_polyfill"
+version = "1.70.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a6cb138bb79a146c1bd460005623e142ef0181e3d0219cb493e02f7d08a35695"
+
 [[package]]
 name = "itertools"
 version = "0.14.0"
@@ -542,6 +679,30 @@ version = "1.0.17"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "92ecc6618181def0457392ccd0ee51198e065e016d1d527a7ac1b6dc7c1f09d2"
 
+[[package]]
+name = "jiff"
+version = "0.2.23"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1a3546dc96b6d42c5f24902af9e2538e82e39ad350b0c766eb3fbf2d8f3d8359"
+dependencies = [
+ "jiff-static",
+ "log",
+ "portable-atomic",
+ "portable-atomic-util",
+ "serde_core",
+]
+
+[[package]]
+name = "jiff-static"
+version = "0.2.23"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2a8c8b344124222efd714b73bb41f8b5120b27a7cc1c75593a6ff768d9d05aa4"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.117",
+]
+
 [[package]]
 name = "js-sys"
 version = "0.3.91"
@@ -690,6 +851,26 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "mould"
+version = "0.4.3"
+dependencies = [
+ "anyhow",
+ "clap",
+ "crossterm",
+ "dirs",
+ "env_logger",
+ "log",
+ "ratatui",
+ "serde",
+ "serde_json",
+ "serde_yaml",
+ "tempfile",
+ "thiserror 2.0.18",
+ "toml",
+ "tui-input",
+]
+
 [[package]]
 name = "nix"
 version = "0.29.0"
@@ -754,6 +935,12 @@ version = "1.21.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9f7c3e4beb33f85d45ae3e3a1792185706c8e16d043238c593331cc7cd313b50"
 
+[[package]]
+name = "once_cell_polyfill"
+version = "1.70.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "384b8ab6d37215f3c5301a95a4accb5d64aa607f1fcb26a11b5303878451b4fe"
+
 [[package]]
 name = "option-ext"
 version = "0.2.0"
@@ -893,6 +1080,15 @@ version = "1.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c33a9471896f1c69cecef8d20cbe2f7accd12527ce60845ff44c153bb2a21b49"
 
+[[package]]
+name = "portable-atomic-util"
+version = "0.2.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "091397be61a01d4be58e7841595bd4bfedb15f1cd54977d79b8271e94ed799a3"
+dependencies = [
+ "portable-atomic",
+]
+
 [[package]]
 name = "powerfmt"
 version = "0.2.0"
@@ -1186,6 +1382,19 @@ dependencies = [
  "serde_core",
 ]
 
+[[package]]
+name = "serde_yaml"
+version = "0.9.34+deprecated"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6a8b1a1a2ebf674015cc02edccce75287f1a0130d394307b36743c2f5d504b47"
+dependencies = [
+ "indexmap",
+ "itoa",
+ "ryu",
+ "serde",
+ "unsafe-libyaml",
+]
+
 [[package]]
 name = "sha2"
 version = "0.10.9"
@@ -1471,6 +1680,16 @@ version = "1.0.6+spec-1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ab16f14aed21ee8bfd8ec22513f7287cd4a91aa92e44edfe2c17ddd004e92607"
 
+[[package]]
+name = "tui-input"
+version = "0.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "79c1ee964298f136020f5f69e0e601f4d3a1f610a7baf1af9fcb96152e8a2c45"
+dependencies = [
+ "ratatui",
+ "unicode-width",
+]
+
 [[package]]
 name = "typenum"
 version = "1.19.0"
@@ -1518,6 +1737,12 @@ version = "0.2.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ebc1c04c71510c7f702b52b7c350734c9ff1295c464a03335b00bb84fc54f853"
 
+[[package]]
+name = "unsafe-libyaml"
+version = "0.2.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "673aac59facbab8a9007c7f6108d11f63b603f7cabff99fabf650fea5c32b861"
+
 [[package]]
 name = "utf8parse"
 version = "0.2.2"

Cargo.toml

@@ -1,19 +1,33 @@
 [package]
-name = "cenv-rs"
-version = "0.1.0"
-edition = "2024"
 authors = ["Nils Pukropp <nils@narl.io>"]
+edition = "2024"
+name = "mould"
+version = "0.4.3"
 
 [[bin]]
-name = "cenv"
+name = "mould"
 path = "src/main.rs"
 
 [dependencies]
+anyhow = "1.0.102"
 crossterm = "0.29.0"
 dirs = "6.0.0"
+env_logger = "0.11.9"
+log = "0.4.29"
 ratatui = "0.30.0"
-serde = { version = "1.0.228", features = ["derive"] }
+serde_json = "1.0.149"
+serde_yaml = "0.9.34"
+thiserror = "2.0.18"
 toml = "1.0.6"
+tui-input = "0.15.0"
+
+[dependencies.clap]
+features = ["derive"]
+version = "4.6.0"
+
+[dependencies.serde]
+features = ["derive"]
+version = "1.0.228"
 
 [dev-dependencies]
 tempfile = "3.27.0"

LICENSE

@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2026 The cenv-rs Contributors
+Copyright (c) 2026 Nils Pukropp <nils@narl.io>
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

README.md

@@ -1,16 +1,22 @@
-# cenv-rs
+# mould
 
-cenv-rs is a Rust-based Terminal User Interface (TUI) tool designed to help developers interactively generate `.env` files from `.env.example` templates. With a focus on speed and usability, it features Vim-like keybindings and out-of-the-box support for theming, defaulting to the Catppuccin Mocha palette.
+mould is a modern Terminal User Interface (TUI) tool designed for interactively generating and editing configuration files from templates. Whether you are setting up a `.env` file from an example, creating a `docker-compose.override.yml`, or editing nested `JSON`, `YAML`, or `TOML` configurations, mould provides a fast, Vim-inspired workflow to get your environment ready.
 
 ## Features
 
-- Parse `.env.example` files to extract keys, default values, and comments.
+- **Universal Format Support**: Handle `.env`, `JSON`, `YAML`, and `TOML` seamlessly.
-- Vim-like keybindings for quick navigation and editing.
+- **Tree View Navigation**: Edit nested data structures (JSON, YAML, TOML) in a beautiful, depth-colored tree view.
-- Built-in theming support with Catppuccin Mocha as the default.
+- **Smart Template Comparison**: Automatically discovers `.env.example` vs `.env` relationships and highlights missing or modified keys.
-- Configurable through a standard TOML file.
+- **Add Missing Keys**: Instantly pull missing keys and their default values from your template into your active configuration with a single keystroke.
+- **Neovim Integration**: Comes with a built-in Neovim plugin for seamless in-editor configuration management.
+- **Docker Compose Integration**: Automatically generate `docker-compose.override.yml` from `docker-compose.yml`.
+- **Vim-inspired Workflow**: Navigate with `j`/`k`, `gg`/`G`, edit with `i`, search with `/`, and save with `:w`.
+- **Modern UI**: A polished, rounded interface featuring a semantic Catppuccin Mocha palette.
+- **Highly Configurable**: Customize keybindings and semantic themes via a simple TOML configuration.
 
 ## Installation
 
+### CLI Application
 Ensure you have Rust and Cargo installed, then run:
 
 ```sh
@@ -21,42 +27,99 @@ Alternatively, you can build from source:
 
 ```sh
 git clone <repository_url>
-cd cenv-rs
+cd mould
 cargo build --release
 ```
 
+### Neovim Plugin
+If you use a plugin manager like `mini.deps`, you can add the repository directly:
+
+```lua
+add({
+	source = 'https://git.narl.io/nvrl/mould-rs',
+	checkout = 'main',
+})
+```
+
 ## Usage
 
-Navigate to a directory containing a `.env.example` file and run:
+Provide an input template file to start editing. `mould` is smart enough to figure out if it's looking at a template or an active file, and will search for its counterpart to provide diffing.
 
 ```sh
-cenv-rs
+mould .env.example
+mould docker-compose.yml
+mould config.template.json -o config.json
 ```
 
-### Keybindings
+### Keybindings (Default)
 
 - **Normal Mode**
   - `j` / `Down`: Move selection down
   - `k` / `Up`: Move selection up
-  - `i`: Edit the value of the currently selected key (Enter Insert Mode)
+  - `gg`: Jump to the top
-  - `:w` or `Enter`: Save the current configuration to `.env`
+  - `G`: Jump to the bottom
-  - `q` or `:q`: Quit the application without saving
+  - `i`: Edit value (cursor at start)
-  - `Esc`: Clear current prompt or return from actions
+  - `A`: Edit value (cursor at end)
+  - `S`: Substitute value (clear and edit)
+  - `o`: Append a new item to the current array
+  - `O`: Prepend a new item to the current array
+  - `dd`: Delete the currently selected variable or group
+  - `u`: Undo the last change
+  - `a`: Add missing value from template to active config
+  - `/`: Search for configuration keys (Jump to matches)
+  - `n`: Jump to the next search match
+  - `N`: Jump to the previous search match
+  - `:w` or `Enter`: Save the current configuration to the output file
+  - `:q` or `q`: Quit the application
+  - `:wq`: Save and quit
+  - `Esc`: Clear current command prompt
 
 - **Insert Mode**
   - Type your value for the selected key.
-  - `Esc`: Return to Normal Mode
+  - Arrow keys: Navigate within the input field
+  - `Enter` / `Esc`: Commit the value and return to Normal Mode
 
 ## Configuration
 
-cenv-rs can be configured using a `config.toml` file located in your user configuration directory (e.g., `~/.config/cenv-rs/config.toml` on Linux/macOS).
+mould can be configured using a `config.toml` file located in your user configuration directory (e.g., `~/.config/mould/config.toml` on Linux/macOS).
 
 Example configuration:
 
 ```toml
+[keybinds]
+down = "j"
+up = "k"
+edit = "i"
+save = ":w"
+quit = ":q"
+normal_mode = "Esc"
+search = "/"
+next_match = "n"
+previous_match = "N"
+jump_top = "gg"
+jump_bottom = "G"
+
 [theme]
-# Default theme is "catppuccin_mocha"
+# Enable transparency to let your terminal background show through
-name = "catppuccin_mocha"
+transparent = false
+
+# Custom color palette (Semantic Catppuccin Mocha defaults)
+bg_normal = "#1e1e2e"
+bg_highlight = "#89b4fa"
+bg_active = "#a6e3a1"
+bg_search = "#cba6f7"
+fg_normal = "#cdd6f4"
+fg_dimmed = "#6c7086"
+fg_highlight = "#1e1e2e"
+fg_warning = "#f38ba8"
+fg_modified = "#fab387"
+fg_accent = "#b4befe"
+border_normal = "#45475a"
+border_active = "#a6e3a1"
+tree_depth_1 = "#b4befe"
+tree_depth_2 = "#cba6f7"
+tree_depth_3 = "#89b4fa"
+tree_depth_4 = "#fab387"
 ```
 
 ## License

config.example.toml

@@ -0,0 +1,47 @@
+# mould Configuration Example
+# Place this file at ~/.config/mould/config.toml (Linux/macOS)
+# or %AppData%\mould\config.toml (Windows)
+
+[theme]
+# If true, skip rendering the background block to let the terminal's transparency show.
+transparent = false
+
+# Colors are specified in hex format ("#RRGGBB").
+# Default values follow the Semantic Catppuccin Mocha palette.
+
+bg_normal = "#1e1e2e"
+bg_highlight = "#89b4fa"
+bg_active = "#a6e3a1"
+bg_search = "#cba6f7"
+fg_normal = "#cdd6f4"
+fg_dimmed = "#6c7086"
+fg_highlight = "#1e1e2e"
+fg_warning = "#f38ba8"
+fg_modified = "#fab387"
+fg_accent = "#b4befe"
+border_normal = "#45475a"
+border_active = "#a6e3a1"
+tree_depth_1 = "#b4befe"
+tree_depth_2 = "#cba6f7"
+tree_depth_3 = "#89b4fa"
+tree_depth_4 = "#fab387"
+
+[keybinds]
+# Keybindings for navigation and application control.
+down = "j"
+up = "k"
+edit = "i"
+edit_append = "A"
+edit_substitute = "S"
+save = ":w"
+quit = ":q"
+normal_mode = "Esc"
+search = "/"
+next_match = "n"
+previous_match = "N"
+jump_top = "gg"
+jump_bottom = "G"
+append_item = "o"
+prepend_item = "O"
+delete_item = "dd"
+undo = "u"

lua/mould/init.lua

@@ -0,0 +1,54 @@
+local M = {}
+
+local function open_floating_terminal(cmd)
+  local buf = vim.api.nvim_create_buf(false, true)
+  local width = math.floor(vim.o.columns * 0.9)
+  local height = math.floor(vim.o.lines * 0.9)
+  local col = math.floor((vim.o.columns - width) / 2)
+  local row = math.floor((vim.o.lines - height) / 2)
+
+  local win_config = {
+    relative = "editor",
+    width = width,
+    height = height,
+    col = col,
+    row = row,
+    style = "minimal",
+    border = "rounded",
+  }
+
+  local win = vim.api.nvim_open_win(buf, true, win_config)
+  
+  -- Record the original buffer to reload it later
+  local original_buf = vim.api.nvim_get_current_buf()
+  local original_file = vim.api.nvim_buf_get_name(original_buf)
+
+  vim.fn.termopen(cmd, {
+    on_exit = function()
+      vim.api.nvim_win_close(win, true)
+      vim.api.nvim_buf_delete(buf, { force = true })
+      
+      -- Reload the original file if it exists
+      if vim.fn.filereadable(original_file) == 1 then
+        vim.schedule(function()
+          vim.cmd("checktime " .. vim.fn.fnameescape(original_file))
+        end)
+      end
+    end,
+  })
+
+  vim.cmd("startinsert")
+end
+
+function M.open()
+  local filepath = vim.api.nvim_buf_get_name(0)
+  if filepath == "" then
+    vim.notify("mould.nvim: Cannot open mould for an unnamed buffer.", vim.log.levels.ERROR)
+    return
+  end
+
+  local cmd = string.format("mould %s", vim.fn.shellescape(filepath))
+  open_floating_terminal(cmd)
+end
+
+return M

plugin/mould.lua

@@ -0,0 +1,8 @@
+if vim.g.loaded_mould == 1 then
+  return
+end
+vim.g.loaded_mould = 1
+
+vim.api.nvim_create_user_command("Mould", function()
+  require("mould").open()
+end, { desc = "Open mould for the current buffer" })

src/app.rs

@@ -1,35 +1,81 @@
-use crate::env::EnvVar;
+use crate::format::ConfigItem;
+use tui_input::Input;
 
+/// Represents the current operating mode of the application.
 pub enum Mode {
+    /// Standard navigation and command mode.
     Normal,
+    /// Active text entry mode for modifying values.
     Insert,
+    /// Active search mode for filtering keys.
+    Search,
 }
 
+pub enum InsertVariant {
+    Start,
+    End,
+    Substitute,
+}
+
+/// The core application state, holding all configuration variables and UI status.
 pub struct App {
-    pub vars: Vec<EnvVar>,
+    /// The list of configuration variables being edited.
+    pub vars: Vec<ConfigItem>,
+    /// Index of the currently selected variable in the list.
     pub selected: usize,
+    /// The current interaction mode (Normal or Insert).
     pub mode: Mode,
+    /// Whether the main application loop should continue running.
     pub running: bool,
+    /// An optional message to display in the status bar (e.g., "Saved to .env").
     pub status_message: Option<String>,
+    /// The active text input buffer for the selected variable.
+    pub input: Input,
+    /// The current search query for filtering keys.
+    pub search_query: String,
+    /// Stack of previous variable states for undo functionality.
+    pub undo_stack: Vec<Vec<ConfigItem>>,
 }
 
 impl App {
-    pub fn new(vars: Vec<EnvVar>) -> Self {
+    /// Initializes a new application instance with the provided variables.
+    pub fn new(vars: Vec<ConfigItem>) -> Self {
+        let initial_input = vars.get(0).and_then(|v| v.value.clone()).unwrap_or_default();
         Self {
             vars,
             selected: 0,
             mode: Mode::Normal,
             running: true,
             status_message: None,
+            input: Input::new(initial_input),
+            search_query: String::new(),
+            undo_stack: Vec::new(),
         }
     }
 
+    /// Returns the indices of variables that match the search query.
+    pub fn matching_indices(&self) -> Vec<usize> {
+        if self.search_query.is_empty() {
+            return Vec::new();
+        }
+        let query = self.search_query.to_lowercase();
+        self.vars
+            .iter()
+            .enumerate()
+            .filter(|(_, v)| v.key.to_lowercase().contains(&query))
+            .map(|(i, _)| i)
+            .collect()
+    }
+
+    /// Moves the selection to the next variable in the list, wrapping around if necessary.
     pub fn next(&mut self) {
         if !self.vars.is_empty() {
             self.selected = (self.selected + 1) % self.vars.len();
+            self.sync_input_with_selected();
         }
     }
 
+    /// Moves the selection to the previous variable in the list, wrapping around if necessary.
     pub fn previous(&mut self) {
         if !self.vars.is_empty() {
             if self.selected == 0 {
@@ -37,19 +83,299 @@ impl App {
             } else {
                 self.selected -= 1;
             }
+            self.sync_input_with_selected();
         }
     }
 
-    pub fn enter_insert(&mut self) {
+    /// Jumps to the top of the list.
+    pub fn jump_top(&mut self) {
+        if !self.vars.is_empty() {
+            self.selected = 0;
+            self.sync_input_with_selected();
+        }
+    }
+
+    /// Jumps to the bottom of the list.
+    pub fn jump_bottom(&mut self) {
+        if !self.vars.is_empty() {
+            self.selected = self.vars.len() - 1;
+            self.sync_input_with_selected();
+        }
+    }
+
+    /// Jumps to the next variable that matches the search query.
+    pub fn jump_next_match(&mut self) {
+        let indices = self.matching_indices();
+        if indices.is_empty() {
+            return;
+        }
+
+        let next_match = indices
+            .iter()
+            .find(|&&i| i > self.selected)
+            .or_else(|| indices.first());
+
+        if let Some(&index) = next_match {
+            self.selected = index;
+            self.sync_input_with_selected();
+        }
+    }
+
+    /// Jumps to the previous variable that matches the search query.
+    pub fn jump_previous_match(&mut self) {
+        let indices = self.matching_indices();
+        if indices.is_empty() {
+            return;
+        }
+
+        let prev_match = indices
+            .iter()
+            .rev()
+            .find(|&&i| i < self.selected)
+            .or_else(|| indices.last());
+
+        if let Some(&index) = prev_match {
+            self.selected = index;
+            self.sync_input_with_selected();
+        }
+    }
+
+    /// Updates the input buffer to reflect the value of the currently selected variable.
+    pub fn sync_input_with_selected(&mut self) {
+        if let Some(var) = self.vars.get(self.selected) {
+            let val = var.value.clone().unwrap_or_default();
+            self.input = Input::new(val);
+        }
+    }
+
+    /// Commits the current text in the input buffer back to the selected variable's value.
+    pub fn commit_input(&mut self) {
+        if let Some(var) = self.vars.get_mut(self.selected) {
+            if !var.is_group {
+                var.value = Some(self.input.value().to_string());
+                var.status = crate::format::ItemStatus::Modified;
+            }
+        }
+    }
+
+    /// Transitions the application into Insert Mode with a specific variant.
+    pub fn enter_insert(&mut self, variant: InsertVariant) {
+        if let Some(var) = self.vars.get(self.selected) {
+            if !var.is_group {
+                self.save_undo_state();
                 self.mode = Mode::Insert;
+                match variant {
+                    InsertVariant::Start => {
+                        use tui_input::InputRequest;
+                        self.input.handle(InputRequest::GoToStart);
+                    }
+                    InsertVariant::End => {
+                        use tui_input::InputRequest;
+                        self.input.handle(InputRequest::GoToEnd);
+                    }
+                    InsertVariant::Substitute => {
+                        self.input = Input::new(String::new());
+                    }
+                }
+            }
+        }
     }
 
+    /// Commits the current input and transitions the application into Normal Mode.
     pub fn enter_normal(&mut self) {
+        self.commit_input();
         self.mode = Mode::Normal;
     }
 
-    #[allow(dead_code)]
+    /// Deletes the currently selected item. If it's a group, deletes all children.
-    pub fn quit(&mut self) {
+    pub fn delete_selected(&mut self) {
-        self.running = false;
+        if self.vars.is_empty() {
+            return;
+        }
+
+        self.save_undo_state();
+        let selected_path = self.vars[self.selected].path.clone();
+        let is_group = self.vars[self.selected].is_group;
+
+        // Identify if the item being removed is an array item
+        let array_info = parse_index(&selected_path);
+
+        // 1. Identify all items to remove
+        let mut to_remove = Vec::new();
+        to_remove.push(self.selected);
+
+        if is_group {
+            let prefix_dot = format!("{}.", selected_path);
+            let prefix_bracket = format!("{}[", selected_path);
+            for (i, var) in self.vars.iter().enumerate() {
+                if i == self.selected {
+                    continue;
+                }
+                if var.path.starts_with(&prefix_dot) || var.path.starts_with(&prefix_bracket) {
+                    to_remove.push(i);
+                }
+            }
+        }
+
+        // 2. Perform removal (reverse order to preserve indices)
+        to_remove.sort_unstable_by(|a, b| b.cmp(a));
+        for i in to_remove {
+            self.vars.remove(i);
+        }
+
+        // 3. Re-index subsequent array items if applicable
+        if let Some((base, removed_idx)) = array_info {
+            let base = base.to_string();
+            for var in self.vars.iter_mut() {
+                if var.path.starts_with(&base) {
+                    // We need to find the index segment that matches this array
+                    if let Some((b, i, suffix)) = find_array_segment(&var.path, &base) {
+                        if b == base && i > removed_idx {
+                            let new_idx = i - 1;
+                            var.path = format!("{}[{}]{}", base, new_idx, suffix);
+                            // Also update key if it matches the old index exactly
+                            if var.key == format!("[{}]", i) {
+                                var.key = format!("[{}]", new_idx);
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        // 4. Adjust selection
+        if self.selected >= self.vars.len() && !self.vars.is_empty() {
+            self.selected = self.vars.len() - 1;
+        }
+        self.sync_input_with_selected();
+    }
+
+    /// Adds a new item to an array if the selected item is part of one.
+    pub fn add_array_item(&mut self, after: bool) {
+        if self.vars.is_empty() {
+            return;
+        }
+
+        self.save_undo_state();
+        let (base, idx, depth) = {
+            let selected_item = &self.vars[self.selected];
+            if selected_item.is_group {
+                return;
+            }
+            let path = &selected_item.path;
+            if let Some((base, idx)) = parse_index(path) {
+                (base.to_string(), idx, selected_item.depth)
+            } else {
+                return;
+            }
+        };
+
+        let new_idx = if after { idx + 1 } else { idx };
+        let insert_pos = if after {
+            self.selected + 1
+        } else {
+            self.selected
+        };
+
+        // 1. Shift all items in this array that have index >= new_idx
+        for var in self.vars.iter_mut() {
+            if var.path.starts_with(&base) {
+                if let Some((b, i)) = parse_index(&var.path) {
+                    if b == base && i >= new_idx {
+                        var.path = format!("{}[{}]", base, i + 1);
+                        // Also update key if it was just the index
+                        if var.key == format!("[{}]", i) {
+                            var.key = format!("[{}]", i + 1);
+                        }
+                    }
+                }
+            }
+        }
+
+        // 2. Insert new item
+        let new_item = ConfigItem {
+            key: format!("[{}]", new_idx),
+            path: format!("{}[{}]", base, new_idx),
+            value: Some("".to_string()),
+            template_value: None,
+            default_value: None,
+            depth,
+            is_group: false,
+            status: crate::format::ItemStatus::Modified,
+            value_type: crate::format::ValueType::String,
+        };
+        self.vars.insert(insert_pos, new_item);
+        self.selected = insert_pos;
+        self.sync_input_with_selected();
+        self.enter_insert(InsertVariant::Start);
+        self.status_message = None;
+    }
+
+    /// Status bar helpers
+    pub fn selected_is_group(&self) -> bool {
+        self.vars.get(self.selected).map(|v| v.is_group).unwrap_or(false)
+    }
+
+    pub fn selected_is_array(&self) -> bool {
+        self.vars.get(self.selected)
+            .map(|v| !v.is_group && v.path.contains('['))
+            .unwrap_or(false)
+    }
+
+    pub fn selected_is_missing(&self) -> bool {
+        self.vars.get(self.selected)
+            .map(|v| v.status == crate::format::ItemStatus::MissingFromActive)
+            .unwrap_or(false)
+    }
+
+    /// Saves the current state of variables to the undo stack.
+    pub fn save_undo_state(&mut self) {
+        self.undo_stack.push(self.vars.clone());
+        if self.undo_stack.len() > 50 {
+            self.undo_stack.remove(0);
+        }
+    }
+
+    /// Reverts to the last saved state of variables.
+    pub fn undo(&mut self) {
+        if let Some(previous_vars) = self.undo_stack.pop() {
+            self.vars = previous_vars;
+            if self.selected >= self.vars.len() && !self.vars.is_empty() {
+                self.selected = self.vars.len() - 1;
+            }
+            self.sync_input_with_selected();
+            self.status_message = Some("Undo applied".to_string());
+        } else {
+            self.status_message = Some("Nothing to undo".to_string());
+        }
     }
 }
+
+fn parse_index(path: &str) -> Option<(&str, usize)> {
+    if let Some(end) = path.rfind(']') {
+        let segment = &path[..=end];
+        if let Some(start) = segment.rfind('[') {
+            if let Ok(idx) = segment[start + 1..end].parse::<usize>() {
+                // Return the base and index
+                return Some((&path[..start], idx));
+            }
+        }
+    }
+    None
+}
+
+/// Helper to find an array segment in a path given a base prefix.
+fn find_array_segment<'a>(path: &'a str, base: &str) -> Option<(&'a str, usize, &'a str)> {
+    if !path.starts_with(base) {
+        return None;
+    }
+    let remaining = &path[base.len()..];
+    if remaining.starts_with('[') {
+        if let Some(end) = remaining.find(']') {
+            if let Ok(idx) = remaining[1..end].parse::<usize>() {
+                return Some((&path[..base.len()], idx, &remaining[end + 1..]));
+            }
+        }
+    }
+    None
+}

src/cli.rs

@@ -0,0 +1,34 @@
+use clap::Parser;
+use std::path::PathBuf;
+
+/// mould: A TUI tool to generate and edit configuration files (.env, json, yaml, toml)
+#[derive(Parser, Debug)]
+#[command(
+    author,
+    version,
+    about = "mould: A TUI tool to generate and edit configuration files (.env, json, yaml, toml)",
+    long_about = "mould allows you to interactively edit and generate configuration files using templates. It supports various formats including .env, JSON, YAML, and TOML. It features a modern TUI with Vim-inspired keybindings and out-of-the-box support for theming.",
+    after_help = "EXAMPLES:\n  mould .env.example\n  mould docker-compose.yml\n  mould config.template.json -o config.json"
+)]
+pub struct Cli {
+    /// The input template file (e.g., .env.example, config.json.template, docker-compose.yml)
+    #[arg(required = false, value_name = "INPUT_FILE")]
+    pub input: Option<PathBuf>,
+
+    /// Optional output file. If not provided, it will be inferred.
+    #[arg(short, long, value_name = "OUTPUT_FILE")]
+    pub output: Option<PathBuf>,
+
+    /// Override the format detection (env, json, yaml, toml)
+    #[arg(short, long, value_name = "FORMAT", value_parser = ["env", "json", "yaml", "toml"])]
+    pub format: Option<String>,
+
+    /// Increase verbosity for logging (can be used multiple times)
+    #[arg(short, long, action = clap::ArgAction::Count)]
+    pub verbose: u8,
+}
+
+/// Parses and returns the command-line arguments.
+pub fn parse() -> Cli {
+    Cli::parse()
+}

src/config.rs

@@ -1,28 +1,165 @@
+use ratatui::style::Color;
 use serde::{Deserialize, Serialize};
 use std::fs;
 
+/// Configuration for the application's appearance.
 #[derive(Debug, Deserialize, Serialize, Clone)]
+#[serde(default)]
 pub struct ThemeConfig {
-    pub name: String,
+    /// If true, skip rendering the background block to let the terminal's transparency show.
+    pub transparent: bool,
+    /// Default background.
+    pub bg_normal: String,
+    /// Background for selected items and standard UI elements.
+    pub bg_highlight: String,
+    /// Active element background (e.g., insert mode).
+    pub bg_active: String,
+    /// Active element background (e.g., search mode).
+    pub bg_search: String,
+    /// Standard text.
+    pub fg_normal: String,
+    /// Secondary/inactive text.
+    pub fg_dimmed: String,
+    /// Text on selected items.
+    pub fg_highlight: String,
+    /// Red/Alert color for missing items.
+    pub fg_warning: String,
+    /// Accent color for modified items.
+    pub fg_modified: String,
+    /// High-contrast accent for titles and active UI elements.
+    pub fg_accent: String,
+    /// Borders.
+    pub border_normal: String,
+    /// Active borders (e.g., input mode).
+    pub border_active: String,
+    /// Color for tree indentation depth 1.
+    pub tree_depth_1: String,
+    /// Color for tree indentation depth 2.
+    pub tree_depth_2: String,
+    /// Color for tree indentation depth 3.
+    pub tree_depth_3: String,
+    /// Color for tree indentation depth 4.
+    pub tree_depth_4: String,
+}
+
+impl ThemeConfig {
+    /// Internal helper to parse a hex color string ("#RRGGBB") into a TUI Color.
+    fn parse_hex(hex: &str) -> Color {
+        let hex = hex.trim_start_matches('#');
+        if hex.len() == 6 {
+            let r = u8::from_str_radix(&hex[0..2], 16).unwrap_or(0);
+            let g = u8::from_str_radix(&hex[2..4], 16).unwrap_or(0);
+            let b = u8::from_str_radix(&hex[4..6], 16).unwrap_or(0);
+            Color::Rgb(r, g, b)
+        } else {
+            Color::Reset
+        }
+    }
+
+    pub fn bg_normal(&self) -> Color { Self::parse_hex(&self.bg_normal) }
+    pub fn bg_highlight(&self) -> Color { Self::parse_hex(&self.bg_highlight) }
+    pub fn bg_active(&self) -> Color { Self::parse_hex(&self.bg_active) }
+    pub fn bg_search(&self) -> Color { Self::parse_hex(&self.bg_search) }
+    pub fn fg_normal(&self) -> Color { Self::parse_hex(&self.fg_normal) }
+    pub fn fg_dimmed(&self) -> Color { Self::parse_hex(&self.fg_dimmed) }
+    pub fn fg_highlight(&self) -> Color { Self::parse_hex(&self.fg_highlight) }
+    pub fn fg_warning(&self) -> Color { Self::parse_hex(&self.fg_warning) }
+    pub fn fg_modified(&self) -> Color { Self::parse_hex(&self.fg_modified) }
+    pub fn fg_accent(&self) -> Color { Self::parse_hex(&self.fg_accent) }
+    pub fn border_normal(&self) -> Color { Self::parse_hex(&self.border_normal) }
+    pub fn border_active(&self) -> Color { Self::parse_hex(&self.border_active) }
+    pub fn tree_depth_1(&self) -> Color { Self::parse_hex(&self.tree_depth_1) }
+    pub fn tree_depth_2(&self) -> Color { Self::parse_hex(&self.tree_depth_2) }
+    pub fn tree_depth_3(&self) -> Color { Self::parse_hex(&self.tree_depth_3) }
+    pub fn tree_depth_4(&self) -> Color { Self::parse_hex(&self.tree_depth_4) }
 }
 
 impl Default for ThemeConfig {
+    /// Default theme: Semantic Catppuccin Mocha.
     fn default() -> Self {
         Self {
-            name: "catppuccin_mocha".to_string(),
+            transparent: false,
+            bg_normal: "#1e1e2e".to_string(), // base
+            bg_highlight: "#89b4fa".to_string(), // blue
+            bg_active: "#a6e3a1".to_string(), // green
+            bg_search: "#cba6f7".to_string(), // mauve
+            fg_normal: "#cdd6f4".to_string(), // text
+            fg_dimmed: "#6c7086".to_string(), // overlay0
+            fg_highlight: "#1e1e2e".to_string(), // base (dark for contrast against highlights)
+            fg_warning: "#f38ba8".to_string(), // red
+            fg_modified: "#fab387".to_string(), // peach
+            fg_accent: "#b4befe".to_string(), // lavender
+            border_normal: "#45475a".to_string(), // surface1
+            border_active: "#a6e3a1".to_string(), // green
+            tree_depth_1: "#b4befe".to_string(), // lavender
+            tree_depth_2: "#cba6f7".to_string(), // mauve
+            tree_depth_3: "#89b4fa".to_string(), // blue
+            tree_depth_4: "#fab387".to_string(), // peach
         }
     }
 }
 
+/// Custom keybindings for navigation and application control.
+#[derive(Debug, Deserialize, Serialize, Clone)]
+#[serde(default)]
+pub struct KeybindsConfig {
+    pub down: String,
+    pub up: String,
+    pub edit: String,
+    pub edit_append: String,
+    pub edit_substitute: String,
+    pub save: String,
+    pub quit: String,
+    pub normal_mode: String,
+    pub search: String,
+    pub next_match: String,
+    pub previous_match: String,
+    pub jump_top: String,
+    pub jump_bottom: String,
+    pub append_item: String,
+    pub prepend_item: String,
+    pub delete_item: String,
+    pub undo: String,
+}
+
+impl Default for KeybindsConfig {
+    fn default() -> Self {
+        Self {
+            down: "j".to_string(),
+            up: "k".to_string(),
+            edit: "i".to_string(),
+            edit_append: "A".to_string(),
+            edit_substitute: "S".to_string(),
+            save: ":w".to_string(),
+            quit: ":q".to_string(),
+            normal_mode: "Esc".to_string(),
+            search: "/".to_string(),
+            next_match: "n".to_string(),
+            previous_match: "N".to_string(),
+            jump_top: "gg".to_string(),
+            jump_bottom: "G".to_string(),
+            append_item: "o".to_string(),
+            prepend_item: "O".to_string(),
+            delete_item: "dd".to_string(),
+            undo: "u".to_string(),
+        }
+    }
+}
+
+/// Root configuration structure for mould.
 #[derive(Debug, Deserialize, Serialize, Default, Clone)]
 pub struct Config {
     #[serde(default)]
     pub theme: ThemeConfig,
+    #[serde(default)]
+    pub keybinds: KeybindsConfig,
 }
 
+/// Loads the configuration from the user's home config directory (~/.config/mould/config.toml).
+/// Falls back to default settings if no configuration is found.
 pub fn load_config() -> Config {
     if let Some(mut config_dir) = dirs::config_dir() {
-        config_dir.push("cenv-rs");
+        config_dir.push("mould");
         config_dir.push("config.toml");
 
         if config_dir.exists() {

src/env.rs

@@ -1,141 +0,0 @@
-use std::fs;
-use std::io::{self, Write};
-use std::path::Path;
-
-#[derive(Debug, Clone)]
-pub struct EnvVar {
-    pub key: String,
-    pub value: String,
-    pub default_value: String,
-}
-
-pub fn parse_env_example<P: AsRef<Path>>(path: P) -> io::Result<Vec<EnvVar>> {
-    let content = fs::read_to_string(path)?;
-    let mut vars = Vec::new();
-
-    for line in content.lines() {
-        let line = line.trim();
-        if line.is_empty() || line.starts_with('#') {
-            continue; // Skip comments and empty lines
-        }
-
-        if let Some((key, val)) = line.split_once('=') {
-            let parsed_val = val.trim().trim_matches('"').trim_matches('\'').to_string();
-            vars.push(EnvVar {
-                key: key.trim().to_string(),
-                value: parsed_val.clone(),
-                default_value: parsed_val,
-            });
-        }
-    }
-
-    Ok(vars)
-}
-
-pub fn merge_env<P: AsRef<Path>>(path: P, vars: &mut Vec<EnvVar>) -> io::Result<()> {
-    if !path.as_ref().exists() {
-        return Ok(());
-    }
-
-    let content = fs::read_to_string(path)?;
-    for line in content.lines() {
-        let line = line.trim();
-        if line.is_empty() || line.starts_with('#') {
-            continue;
-        }
-
-        if let Some((key, val)) = line.split_once('=') {
-            let key = key.trim();
-            let parsed_val = val.trim().trim_matches('"').trim_matches('\'').to_string();
-
-            if let Some(var) = vars.iter_mut().find(|v| v.key == key) {
-                var.value = parsed_val;
-            } else {
-                vars.push(EnvVar {
-                    key: key.to_string(),
-                    value: parsed_val.clone(),
-                    default_value: String::new(),
-                });
-            }
-        }
-    }
-
-    Ok(())
-}
-
-pub fn write_env<P: AsRef<Path>>(path: P, vars: &[EnvVar]) -> io::Result<()> {
-    let mut file = fs::File::create(path)?;
-    for var in vars {
-        writeln!(file, "{}={}", var.key, var.value)?;
-    }
-    Ok(())
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use std::io::Write;
-    use tempfile::NamedTempFile;
-
-    #[test]
-    fn test_parse_env_example() {
-        let mut file = NamedTempFile::new().unwrap();
-        writeln!(
-            file,
-            "# A comment\nKEY1=value1\nKEY2=\"value2\"\nKEY3='value3'\nEMPTY="
-        )
-        .unwrap();
-
-        let vars = parse_env_example(file.path()).unwrap();
-        assert_eq!(vars.len(), 4);
-        assert_eq!(vars[0].key, "KEY1");
-        assert_eq!(vars[0].value, "value1");
-        assert_eq!(vars[0].default_value, "value1");
-        assert_eq!(vars[1].key, "KEY2");
-        assert_eq!(vars[1].value, "value2");
-        assert_eq!(vars[2].key, "KEY3");
-        assert_eq!(vars[2].value, "value3");
-        assert_eq!(vars[3].key, "EMPTY");
-        assert_eq!(vars[3].value, "");
-    }
-
-    #[test]
-    fn test_merge_env() {
-        let mut example_file = NamedTempFile::new().unwrap();
-        writeln!(example_file, "KEY1=default1\nKEY2=default2").unwrap();
-        let mut vars = parse_env_example(example_file.path()).unwrap();
-
-        let mut env_file = NamedTempFile::new().unwrap();
-        writeln!(env_file, "KEY1=custom1\nKEY3=custom3").unwrap();
-
-        merge_env(env_file.path(), &mut vars).unwrap();
-
-        assert_eq!(vars.len(), 3);
-        assert_eq!(vars[0].key, "KEY1");
-        assert_eq!(vars[0].value, "custom1");
-        assert_eq!(vars[0].default_value, "default1");
-
-        assert_eq!(vars[1].key, "KEY2");
-        assert_eq!(vars[1].value, "default2");
-        assert_eq!(vars[1].default_value, "default2");
-
-        assert_eq!(vars[2].key, "KEY3");
-        assert_eq!(vars[2].value, "custom3");
-        assert_eq!(vars[2].default_value, "");
-    }
-
-    #[test]
-    fn test_write_env() {
-        let file = NamedTempFile::new().unwrap();
-        let vars = vec![EnvVar {
-            key: "KEY1".to_string(),
-            value: "value1".to_string(),
-            default_value: "def".to_string(),
-        }];
-
-        write_env(file.path(), &vars).unwrap();
-
-        let content = fs::read_to_string(file.path()).unwrap();
-        assert_eq!(content.trim(), "KEY1=value1");
-    }
-}

src/error.rs

@@ -0,0 +1,18 @@
+use std::io;
+use thiserror::Error;
+
+/// Custom error types for the mould application.
+#[derive(Error, Debug)]
+pub enum MouldError {
+    #[error("IO error: {0}")]
+    Io(#[from] io::Error),
+
+    #[error("Format error: {0}")]
+    Format(String),
+
+    #[error("File not found: {0}")]
+    FileNotFound(String),
+
+    #[error("Terminal error: {0}")]
+    Terminal(String),
+}

src/format/env.rs

@@ -0,0 +1,173 @@
+use super::{ConfigItem, FormatHandler, ItemStatus, ValueType};
+use std::fs;
+use std::io::{self, Write};
+use std::path::Path;
+
+pub struct EnvHandler;
+
+impl FormatHandler for EnvHandler {
+    fn parse(&self, path: &Path) -> io::Result<Vec<ConfigItem>> {
+        let content = fs::read_to_string(path)?;
+        let mut vars = Vec::new();
+
+        for line in content.lines() {
+            let line = line.trim();
+            if line.is_empty() || line.starts_with('#') {
+                continue; // Skip comments and empty lines
+            }
+
+            if let Some((key, val)) = line.split_once('=') {
+                let parsed_val = val.trim().trim_matches('"').trim_matches('\'').to_string();
+                vars.push(ConfigItem {
+                    key: key.trim().to_string(),
+                    path: key.trim().to_string(),
+                    value: Some(parsed_val.clone()),
+                    template_value: Some(parsed_val.clone()),
+                    default_value: Some(parsed_val),
+                    depth: 0,
+                    is_group: false,
+                    status: ItemStatus::Present,
+                    value_type: ValueType::String,
+                });
+            }
+        }
+
+        Ok(vars)
+    }
+
+    fn merge(&self, path: &Path, vars: &mut Vec<ConfigItem>) -> io::Result<()> {
+        if !path.exists() {
+            return Ok(());
+        }
+
+        let content = fs::read_to_string(path)?;
+        for line in content.lines() {
+            let line = line.trim();
+            if line.is_empty() || line.starts_with('#') {
+                continue;
+            }
+
+            if let Some((key, val)) = line.split_once('=') {
+                let key = key.trim();
+                let parsed_val = val.trim().trim_matches('"').trim_matches('\'').to_string();
+
+                if let Some(var) = vars.iter_mut().find(|v| v.key == key) {
+                    if var.value.as_deref() != Some(&parsed_val) {
+                        var.value = Some(parsed_val);
+                        var.status = ItemStatus::Modified;
+                    }
+                } else {
+                    vars.push(ConfigItem {
+                        key: key.to_string(),
+                        path: key.to_string(),
+                        value: Some(parsed_val),
+                        template_value: None,
+                        default_value: None,
+                        depth: 0,
+                        is_group: false,
+                        status: ItemStatus::MissingFromTemplate,
+                        value_type: ValueType::String,
+                    });
+                }
+            }
+        }
+        
+        // Mark missing from active
+        for var in vars.iter_mut() {
+            if var.status == ItemStatus::Present && var.value.is_none() {
+                var.status = ItemStatus::MissingFromActive;
+            }
+        }
+
+        Ok(())
+    }
+
+    fn write(&self, path: &Path, vars: &[ConfigItem]) -> io::Result<()> {
+        let mut file = fs::File::create(path)?;
+        for var in vars {
+            if !var.is_group {
+                let val = var.value.as_deref()
+                    .or(var.template_value.as_deref())
+                    .unwrap_or("");
+                writeln!(file, "{}={}", var.key, val)?;
+            }
+        }
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::io::Write;
+    use tempfile::NamedTempFile;
+
+    #[test]
+    fn test_parse_env_example() {
+        let mut file = NamedTempFile::new().unwrap();
+        writeln!(
+            file,
+            "# A comment\nKEY1=value1\nKEY2=\"value2\"\nKEY3='value3'\nEMPTY="
+        )
+        .unwrap();
+
+        let handler = EnvHandler;
+        let vars = handler.parse(file.path()).unwrap();
+        assert_eq!(vars.len(), 4);
+        assert_eq!(vars[0].key, "KEY1");
+        assert_eq!(vars[0].value.as_deref(), Some("value1"));
+        assert_eq!(vars[1].key, "KEY2");
+        assert_eq!(vars[1].value.as_deref(), Some("value2"));
+        assert_eq!(vars[2].key, "KEY3");
+        assert_eq!(vars[2].value.as_deref(), Some("value3"));
+        assert_eq!(vars[3].key, "EMPTY");
+        assert_eq!(vars[3].value.as_deref(), Some(""));
+    }
+
+    #[test]
+    fn test_merge_env() {
+        let mut example_file = NamedTempFile::new().unwrap();
+        writeln!(example_file, "KEY1=default1\nKEY2=default2").unwrap();
+        let handler = EnvHandler;
+        let mut vars = handler.parse(example_file.path()).unwrap();
+
+        let mut env_file = NamedTempFile::new().unwrap();
+        writeln!(env_file, "KEY1=custom1\nKEY3=custom3").unwrap();
+
+        handler.merge(env_file.path(), &mut vars).unwrap();
+
+        assert_eq!(vars.len(), 3);
+        assert_eq!(vars[0].key, "KEY1");
+        assert_eq!(vars[0].value.as_deref(), Some("custom1"));
+        assert_eq!(vars[0].status, ItemStatus::Modified);
+
+        assert_eq!(vars[1].key, "KEY2");
+        assert_eq!(vars[1].value.as_deref(), Some("default2"));
+        
+        assert_eq!(vars[2].key, "KEY3");
+        assert_eq!(vars[2].value.as_deref(), Some("custom3"));
+        assert_eq!(vars[2].status, ItemStatus::MissingFromTemplate);
+    }
+
+    #[test]
+    fn test_write_env() {
+        let file = NamedTempFile::new().unwrap();
+        let vars = vec![ConfigItem {
+            key: "KEY1".to_string(),
+            path: "KEY1".to_string(),
+            value: Some("value1".to_string()),
+            template_value: None,
+            default_value: None,
+            depth: 0,
+            is_group: false,
+            status: ItemStatus::Present,
+            value_type: ValueType::String,
+        }];
+
+        let handler = EnvHandler;
+        handler.write(file.path(), &vars).unwrap();
+
+        let content = fs::read_to_string(file.path()).unwrap();
+        assert_eq!(content.trim(), "KEY1=value1");
+    }
+}

src/format/hierarchical.rs

@@ -0,0 +1,353 @@
+use super::{ConfigItem, FormatHandler, FormatType, ItemStatus, ValueType};
+use serde_json::{Map, Value};
+use std::fs;
+use std::io;
+use std::path::Path;
+
+pub struct HierarchicalHandler {
+    format_type: FormatType,
+}
+
+impl HierarchicalHandler {
+    pub fn new(format_type: FormatType) -> Self {
+        Self { format_type }
+    }
+
+    fn read_value(&self, path: &Path) -> io::Result<Value> {
+        let content = fs::read_to_string(path)?;
+        let value = match self.format_type {
+            FormatType::Json => serde_json::from_str(&content)
+                .map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?,
+            FormatType::Yaml => serde_yaml::from_str(&content)
+                .map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?,
+            FormatType::Toml => toml::from_str(&content)
+                .map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?,
+            _ => unreachable!(),
+        };
+        Ok(value)
+    }
+
+    fn write_value(&self, path: &Path, value: &Value) -> io::Result<()> {
+        let content = match self.format_type {
+            FormatType::Json => serde_json::to_string_pretty(value)
+                .map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?,
+            FormatType::Yaml => serde_yaml::to_string(value)
+                .map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?,
+            FormatType::Toml => {
+                // toml requires the root to be a table
+                if value.is_object() {
+                    let toml_value: toml::Value = serde_json::from_value(value.clone())
+                        .map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?;
+                    toml::to_string_pretty(&toml_value)
+                        .map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?
+                } else {
+                    return Err(io::Error::new(
+                        io::ErrorKind::InvalidData,
+                        "Root of TOML must be an object",
+                    ));
+                }
+            }
+            _ => unreachable!(),
+        };
+        fs::write(path, content)
+    }
+}
+
+fn flatten(value: &Value, prefix: &str, depth: usize, key_name: &str, vars: &mut Vec<ConfigItem>) {
+    let path = if prefix.is_empty() {
+        key_name.to_string()
+    } else if key_name.is_empty() {
+        prefix.to_string()
+    } else if key_name.starts_with('[') {
+        format!("{}{}", prefix, key_name)
+    } else {
+        format!("{}.{}", prefix, key_name)
+    };
+
+    match value {
+        Value::Object(map) => {
+            if !path.is_empty() {
+                vars.push(ConfigItem {
+                    key: key_name.to_string(),
+                    path: path.clone(),
+                    value: None,
+                    template_value: None,
+                    default_value: None,
+                    depth,
+                    is_group: true,
+                    status: ItemStatus::Present,
+                    value_type: ValueType::Null,
+                });
+            }
+            let next_depth = if path.is_empty() { depth } else { depth + 1 };
+            for (k, v) in map {
+                flatten(v, &path, next_depth, k, vars);
+            }
+        }
+        Value::Array(arr) => {
+            if !path.is_empty() {
+                vars.push(ConfigItem {
+                    key: key_name.to_string(),
+                    path: path.clone(),
+                    value: None,
+                    template_value: None,
+                    default_value: None,
+                    depth,
+                    is_group: true,
+                    status: ItemStatus::Present,
+                    value_type: ValueType::Null,
+                });
+            }
+            let next_depth = if path.is_empty() { depth } else { depth + 1 };
+            for (i, v) in arr.iter().enumerate() {
+                let array_key = format!("[{}]", i);
+                flatten(v, &path, next_depth, &array_key, vars);
+            }
+        }
+        Value::String(s) => {
+            vars.push(ConfigItem {
+                key: key_name.to_string(),
+                path: path.clone(),
+                value: Some(s.clone()),
+                template_value: Some(s.clone()),
+                default_value: Some(s.clone()),
+                depth,
+                is_group: false,
+                status: ItemStatus::Present,
+                value_type: ValueType::String,
+            });
+        }
+        Value::Number(n) => {
+            let s = n.to_string();
+            vars.push(ConfigItem {
+                key: key_name.to_string(),
+                path: path.clone(),
+                value: Some(s.clone()),
+                template_value: Some(s.clone()),
+                default_value: Some(s.clone()),
+                depth,
+                is_group: false,
+                status: ItemStatus::Present,
+                value_type: ValueType::Number,
+            });
+        }
+        Value::Bool(b) => {
+            let s = b.to_string();
+            vars.push(ConfigItem {
+                key: key_name.to_string(),
+                path: path.clone(),
+                value: Some(s.clone()),
+                template_value: Some(s.clone()),
+                default_value: Some(s.clone()),
+                depth,
+                is_group: false,
+                status: ItemStatus::Present,
+                value_type: ValueType::Bool,
+            });
+        }
+        Value::Null => {
+            vars.push(ConfigItem {
+                key: key_name.to_string(),
+                path: path.clone(),
+                value: Some("".to_string()),
+                template_value: Some("".to_string()),
+                default_value: Some("".to_string()),
+                depth,
+                is_group: false,
+                status: ItemStatus::Present,
+                value_type: ValueType::Null,
+            });
+        }
+    }
+}
+
+impl FormatHandler for HierarchicalHandler {
+    fn parse(&self, path: &Path) -> io::Result<Vec<ConfigItem>> {
+        let value = self.read_value(path)?;
+        let mut vars = Vec::new();
+        flatten(&value, "", 0, "", &mut vars);
+        Ok(vars)
+    }
+
+    fn merge(&self, path: &Path, vars: &mut Vec<ConfigItem>) -> io::Result<()> {
+        if !path.exists() {
+            return Ok(());
+        }
+        let existing_value = self.read_value(path)?;
+        let mut existing_vars = Vec::new();
+        flatten(&existing_value, "", 0, "", &mut existing_vars);
+
+        for var in vars.iter_mut() {
+            if let Some(existing) = existing_vars.iter().find(|v| v.path == var.path) {
+                if var.value != existing.value {
+                    var.value = existing.value.clone();
+                    var.status = ItemStatus::Modified;
+                }
+            } else {
+                var.status = ItemStatus::MissingFromActive;
+            }
+        }
+        
+        // Find keys in active that are not in template
+        let mut to_add = Vec::new();
+        for existing in existing_vars {
+            if !vars.iter().any(|v| v.path == existing.path) {
+                let mut new_item = existing.clone();
+                new_item.status = ItemStatus::MissingFromTemplate;
+                new_item.template_value = None;
+                new_item.default_value = None;
+                to_add.push(new_item);
+            }
+        }
+        
+        // Basic insertion logic for extra keys (could be improved to insert at correct depth/position)
+        vars.extend(to_add);
+
+        Ok(())
+    }
+
+    fn write(&self, path: &Path, vars: &[ConfigItem]) -> io::Result<()> {
+        let mut root = Value::Object(Map::new());
+        for var in vars {
+            if !var.is_group {
+                let val = var.value.as_deref()
+                    .or(var.template_value.as_deref())
+                    .unwrap_or("");
+                insert_into_value(&mut root, &var.path, val, var.value_type);
+            }
+        }
+        self.write_value(path, &root)
+    }
+}
+
+fn insert_into_value(root: &mut Value, path: &str, new_val_str: &str, value_type: ValueType) {
+    let mut parts = path.split('.');
+    let last_part = match parts.next_back() {
+        Some(p) => p,
+        None => return,
+    };
+
+    let mut current = root;
+    for part in parts {
+        let (key, idx) = parse_array_key(part);
+        if !current.is_object() {
+            *current = Value::Object(Map::new());
+        }
+        let map = current.as_object_mut().unwrap();
+
+        let next_node = map.entry(key.to_string()).or_insert_with(|| {
+            if idx.is_some() {
+                Value::Array(Vec::new())
+            } else {
+                Value::Object(Map::new())
+            }
+        });
+
+        if let Some(i) = idx {
+            if !next_node.is_array() {
+                *next_node = Value::Array(Vec::new());
+            }
+            let arr = next_node.as_array_mut().unwrap();
+            while arr.len() <= i {
+                arr.push(Value::Object(Map::new()));
+            }
+            current = &mut arr[i];
+        } else {
+            current = next_node;
+        }
+    }
+
+    let (final_key, final_idx) = parse_array_key(last_part);
+    if !current.is_object() {
+        *current = Value::Object(Map::new());
+    }
+    let map = current.as_object_mut().unwrap();
+
+    // Use the preserved ValueType instead of aggressive inference
+    let final_val = match value_type {
+        ValueType::Number => {
+            if let Ok(n) = new_val_str.parse::<i64>() {
+                Value::Number(n.into())
+            } else if let Ok(f) = new_val_str.parse::<f64>() {
+                if let Some(n) = serde_json::Number::from_f64(f) {
+                    Value::Number(n)
+                } else {
+                    Value::String(new_val_str.to_string())
+                }
+            } else {
+                Value::String(new_val_str.to_string())
+            }
+        }
+        ValueType::Bool => {
+            if let Ok(b) = new_val_str.parse::<bool>() {
+                Value::Bool(b)
+            } else {
+                Value::String(new_val_str.to_string())
+            }
+        }
+        ValueType::Null if new_val_str.is_empty() => Value::Null,
+        _ => Value::String(new_val_str.to_string()),
+    };
+
+    if let Some(i) = final_idx {
+        let next_node = map
+            .entry(final_key.to_string())
+            .or_insert_with(|| Value::Array(Vec::new()));
+        if !next_node.is_array() {
+            *next_node = Value::Array(Vec::new());
+        }
+        let arr = next_node.as_array_mut().unwrap();
+        while arr.len() <= i {
+            arr.push(Value::Null);
+        }
+        arr[i] = final_val;
+    } else {
+        map.insert(final_key.to_string(), final_val);
+    }
+}
+
+fn parse_array_key(part: &str) -> (&str, Option<usize>) {
+    if part.ends_with(']') && part.contains('[') {
+        let start_idx = part.find('[').unwrap();
+        let key = &part[..start_idx];
+        let idx = part[start_idx + 1..part.len() - 1].parse::<usize>().ok();
+        (key, idx)
+    } else {
+        (part, None)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_flatten_unflatten() {
+        let mut vars = Vec::new();
+        let json = serde_json::json!({
+            "services": {
+                "web": {
+                    "ports": ["8080:80"],
+                    "environment": {
+                        "DEBUG": true
+                    }
+                }
+            }
+        });
+
+        flatten(&json, "", 0, "", &mut vars);
+        assert_eq!(vars.len(), 6);
+
+        let mut root = Value::Object(Map::new());
+        for var in vars {
+            if !var.is_group {
+                insert_into_value(&mut root, &var.path, var.value.as_deref().unwrap_or(""), var.value_type);
+            }
+        }
+
+        // When unflattening, it parses bool back
+        let unflattened_json = serde_json::to_string(&root).unwrap();
+        assert!(unflattened_json.contains("\"8080:80\""));
+        assert!(unflattened_json.contains("true"));
+    }
+}

src/format/mod.rs

@@ -0,0 +1,80 @@
+use std::io;
+use std::path::Path;
+
+pub mod env;
+pub mod hierarchical;
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ItemStatus {
+    Present,
+    MissingFromActive,
+    MissingFromTemplate,
+    Modified,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum ValueType {
+    String,
+    Number,
+    Bool,
+    Null,
+}
+
+#[derive(Debug, Clone)]
+pub struct ConfigItem {
+    pub key: String,
+    pub path: String,
+    pub value: Option<String>,
+    pub template_value: Option<String>,
+    pub default_value: Option<String>,
+    pub depth: usize,
+    pub is_group: bool,
+    pub status: ItemStatus,
+    pub value_type: ValueType,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum FormatType {
+    Env,
+    Json,
+    Yaml,
+    Toml,
+}
+
+pub trait FormatHandler {
+    fn parse(&self, path: &Path) -> io::Result<Vec<ConfigItem>>;
+    fn merge(&self, path: &Path, vars: &mut Vec<ConfigItem>) -> io::Result<()>;
+    fn write(&self, path: &Path, vars: &[ConfigItem]) -> io::Result<()>;
+}
+
+pub fn detect_format(path: &Path, override_format: Option<String>) -> FormatType {
+    if let Some(fmt) = override_format {
+        match fmt.to_lowercase().as_str() {
+            "env" => return FormatType::Env,
+            "json" => return FormatType::Json,
+            "yaml" | "yml" => return FormatType::Yaml,
+            "toml" => return FormatType::Toml,
+            _ => {}
+        }
+    }
+
+    let file_name = path.file_name().unwrap_or_default().to_string_lossy();
+    if file_name.ends_with(".json") {
+        FormatType::Json
+    } else if file_name.ends_with(".yaml") || file_name.ends_with(".yml") {
+        FormatType::Yaml
+    } else if file_name.ends_with(".toml") {
+        FormatType::Toml
+    } else {
+        FormatType::Env
+    }
+}
+
+pub fn get_handler(format: FormatType) -> Box<dyn FormatHandler> {
+    match format {
+        FormatType::Env => Box::new(env::EnvHandler),
+        FormatType::Json => Box::new(hierarchical::HierarchicalHandler::new(FormatType::Json)),
+        FormatType::Yaml => Box::new(hierarchical::HierarchicalHandler::new(FormatType::Yaml)),
+        FormatType::Toml => Box::new(hierarchical::HierarchicalHandler::new(FormatType::Toml)),
+    }
+}

src/main.rs

@@ -1,171 +1,151 @@
 mod app;
+mod cli;
 mod config;
-mod env;
+mod error;
+mod format;
+mod runner;
 mod ui;
+mod resolver;
 
-use app::{App, Mode};
+use app::App;
 use config::load_config;
-use env::{merge_env, parse_env_example, write_env};
+use error::MouldError;
-use std::error::Error;
+use format::{detect_format, get_handler};
+use log::{error, info, warn};
+use runner::AppRunner;
 use std::io;
 
 use crossterm::{
-    event::{self, DisableMouseCapture, EnableMouseCapture, Event, KeyCode},
+    event::{DisableMouseCapture, EnableMouseCapture},
     execute,
     terminal::{EnterAlternateScreen, LeaveAlternateScreen, disable_raw_mode, enable_raw_mode},
 };
-use ratatui::{
+use ratatui::{Terminal, backend::CrosstermBackend};
-    Terminal,
-    backend::{Backend, CrosstermBackend},
-};
 
-fn main() -> Result<(), Box<dyn Error>> {
+fn main() -> anyhow::Result<()> {
-    let example_path = ".env.example";
+    let args = cli::parse();
-    let env_path = ".env";
 
-    // Load vars
+    // Initialize logger with verbosity from CLI
-    let mut vars = parse_env_example(example_path).unwrap_or_else(|_| vec![]);
+    let log_level = match args.verbose {
+        0 => log::LevelFilter::Warn,
+        1 => log::LevelFilter::Info,
+        _ => log::LevelFilter::Debug,
+    };
+    env_logger::Builder::new()
+        .filter_level(log_level)
+        .format_timestamp(None)
+        .init();
+
+    let input_path = match args.input {
+        Some(path) => {
+            if !path.exists() {
+                error!("Input file not found: {}", path.display());
+                return Err(MouldError::FileNotFound(path.display().to_string()).into());
+            }
+            path
+        }
+        None => match resolver::find_input_file() {
+            Some(path) => {
+                info!("Discovered template: {}", path.display());
+                path
+            }
+            None => {
+                error!("No template file provided and none discovered in current directory.");
+                println!("Usage: mould <INPUT_FILE>");
+                println!("Supported defaults: .env.example, compose.yml, docker-compose.yml, etc.");
+                return Err(MouldError::FileNotFound("None".to_string()).into());
+            }
+        },
+    };
+
+    info!("Input: {}", input_path.display());
+
+    let format_type = detect_format(&input_path, args.format);
+    let handler = get_handler(format_type);
+
+    // Smart Comparison Logic
+    let (active_path, template_path) = resolver::resolve_paths(&input_path);
+
+    let output_path = args
+        .output
+        .unwrap_or_else(|| active_path.clone().unwrap_or_else(|| resolver::determine_output_path(&input_path)));
+
+    info!("Output: {}", output_path.display());
+
+    // 1. Load active config if it exists
+    let mut vars = if let Some(active) = &active_path {
+        handler.parse(active).unwrap_or_default()
+    } else {
+        Vec::new()
+    };
+
+    // 2. Load template config and merge
+    if let Some(template) = &template_path {
+        info!("Comparing with template: {}", template.display());
+        let template_vars = handler.parse(template).unwrap_or_default();
         if vars.is_empty() {
-        println!("No variables found in .env.example or file does not exist.");
+             vars = template_vars;
-        println!("Please run this tool in a directory with a valid .env.example file.");
+             // If we only have template, everything is missing from active initially
-        return Ok(());
+             for v in vars.iter_mut() {
+                 v.status = crate::format::ItemStatus::MissingFromActive;
+                 v.value = None;
+             }
+        } else {
+             // Merge template into active
+             handler.merge(template, &mut vars).unwrap_or_default();
+        }
+    } else if vars.is_empty() {
+        // Fallback if no template and active is empty
+         vars = handler.parse(&input_path).map_err(|e| {
+            error!("Failed to parse input file: {}", e);
+            MouldError::Format(format!("Failed to parse {}: {}", input_path.display(), e))
+        })?;
     }
 
-    // Merge existing .env if present
+    if vars.is_empty() {
-    let _ = merge_env(env_path, &mut vars);
+        warn!("No variables found.");
+    }
 
     let config = load_config();
     let mut app = App::new(vars);
 
-    // Setup terminal
+    // Terminal lifecycle
-    enable_raw_mode()?;
+    enable_raw_mode()
+        .map_err(|e| MouldError::Terminal(format!("Failed to enable raw mode: {}", e)))?;
     let mut stdout = io::stdout();
-    execute!(stdout, EnterAlternateScreen, EnableMouseCapture)?;
+    execute!(stdout, EnterAlternateScreen, EnableMouseCapture)
+        .map_err(|e| MouldError::Terminal(format!("Failed to enter alternate screen: {}", e)))?;
     let backend = CrosstermBackend::new(stdout);
-    let mut terminal = Terminal::new(backend)?;
+    let mut terminal = Terminal::new(backend)
+        .map_err(|e| MouldError::Terminal(format!("Failed to create terminal backend: {}", e)))?;
 
-    // Run app
+    let mut runner = AppRunner::new(
-    let res = run_app(&mut terminal, &mut app, &config, env_path);
+        &mut terminal,
+        &mut app,
+        &config,
+        &output_path,
+        handler.as_ref(),
+    );
+    let res = runner.run();
 
-    // Restore terminal
+    // Restoration
-    disable_raw_mode()?;
+    disable_raw_mode().ok();
     execute!(
         terminal.backend_mut(),
         LeaveAlternateScreen,
         DisableMouseCapture
-    )?;
+    )
-    terminal.show_cursor()?;
+    .ok();
-
+    terminal.show_cursor().ok();
-    if let Err(err) = res {
-        println!("{:?}", err);
-    }
 
+    match res {
+        Ok(_) => {
+            info!("Successfully finished mould session.");
             Ok(())
-}
+        }
-
+        Err(e) => {
-fn run_app<B: Backend>(
+            error!("Application error during run: {}", e);
-    terminal: &mut Terminal<B>,
+            Err(e.into())
-    app: &mut App,
+        }
-    config: &config::Config,
+    }
-    env_path: &str,
-) -> io::Result<()>
-where
-    io::Error: From<B::Error>,
-{
-    // For handling commands like :w, :q
-    let mut command_buffer = String::new();
-
-    loop {
-        terminal.draw(|f| ui::draw(f, app, config))?;
-
-        if let Event::Key(key) = event::read()? {
-            match app.mode {
-                Mode::Normal => {
-                    if !command_buffer.is_empty() {
-                        if key.code == KeyCode::Enter {
-                            match command_buffer.as_str() {
-                                ":w" => {
-                                    if write_env(env_path, &app.vars).is_ok() {
-                                        app.status_message = Some("Saved to .env".to_string());
-                                    } else {
-                                        app.status_message =
-                                            Some("Error saving to .env".to_string());
-                                    }
-                                }
-                                ":q" => return Ok(()),
-                                ":wq" => {
-                                    write_env(env_path, &app.vars)?;
-                                    return Ok(());
-                                }
-                                _ => {
-                                    app.status_message = Some("Unknown command".to_string());
-                                }
-                            }
-                            command_buffer.clear();
-                        } else if key.code == KeyCode::Esc {
-                            command_buffer.clear();
-                            app.status_message = None;
-                        } else if key.code == KeyCode::Backspace {
-                            command_buffer.pop();
-                            if command_buffer.is_empty() {
-                                app.status_message = None;
-                            } else {
-                                app.status_message = Some(command_buffer.clone());
-                            }
-                        } else if let KeyCode::Char(c) = key.code {
-                            command_buffer.push(c);
-                            app.status_message = Some(command_buffer.clone());
-                        }
-                    } else {
-                        match key.code {
-                            KeyCode::Char('q') => return Ok(()),
-                            KeyCode::Char('j') | KeyCode::Down => app.next(),
-                            KeyCode::Char('k') | KeyCode::Up => app.previous(),
-                            KeyCode::Char('i') => {
-                                app.enter_insert();
-                                app.status_message = None;
-                            }
-                            KeyCode::Char(':') => {
-                                command_buffer.push(':');
-                                app.status_message = Some(command_buffer.clone());
-                            }
-                            KeyCode::Enter => {
-                                // Default action for Enter in Normal mode is save
-                                if write_env(env_path, &app.vars).is_ok() {
-                                    app.status_message = Some("Saved to .env".to_string());
-                                } else {
-                                    app.status_message = Some("Error saving to .env".to_string());
-                                }
-                            }
-                            _ => {}
-                        }
-                    }
-                }
-                Mode::Insert => match key.code {
-                    KeyCode::Esc => {
-                        app.enter_normal();
-                    }
-                    KeyCode::Char(c) => {
-                        if let Some(var) = app.vars.get_mut(app.selected) {
-                            var.value.push(c);
-                        }
-                    }
-                    KeyCode::Backspace => {
-                        if let Some(var) = app.vars.get_mut(app.selected) {
-                            var.value.pop();
-                        }
-                    }
-                    KeyCode::Enter => {
-                        app.enter_normal();
-                    }
-                    _ => {}
-                },
-            }
-        }
-
-        if !app.running {
-            break;
-        }
-    }
-    Ok(())
 }

src/resolver.rs

@@ -0,0 +1,193 @@
+use std::path::{Path, PathBuf};
+
+pub struct Rule {
+    pub template_suffix: &'static str,
+    pub active_suffix: &'static str,
+    pub is_exact_match: bool,
+}
+
+pub const RULES: &[Rule] = &[
+    // Exact matches
+    Rule { template_suffix: "compose.yml", active_suffix: "compose.override.yml", is_exact_match: true },
+    Rule { template_suffix: "compose.yaml", active_suffix: "compose.override.yaml", is_exact_match: true },
+    Rule { template_suffix: "docker-compose.yml", active_suffix: "docker-compose.override.yml", is_exact_match: true },
+    Rule { template_suffix: "docker-compose.yaml", active_suffix: "docker-compose.override.yaml", is_exact_match: true },
+    
+    // Pattern matches
+    Rule { template_suffix: ".env.example", active_suffix: ".env", is_exact_match: false },
+    Rule { template_suffix: ".env.template", active_suffix: ".env", is_exact_match: false },
+    Rule { template_suffix: ".example.json", active_suffix: ".json", is_exact_match: false },
+    Rule { template_suffix: ".template.json", active_suffix: ".json", is_exact_match: false },
+    Rule { template_suffix: ".example.yml", active_suffix: ".yml", is_exact_match: false },
+    Rule { template_suffix: ".template.yml", active_suffix: ".yml", is_exact_match: false },
+    Rule { template_suffix: ".example.yaml", active_suffix: ".yaml", is_exact_match: false },
+    Rule { template_suffix: ".template.yaml", active_suffix: ".yaml", is_exact_match: false },
+    Rule { template_suffix: ".example.toml", active_suffix: ".toml", is_exact_match: false },
+    Rule { template_suffix: ".template.toml", active_suffix: ".toml", is_exact_match: false },
+];
+
+pub const DEFAULT_CANDIDATES: &[&str] = &[
+    ".env.example",
+    "compose.yml",
+    "docker-compose.yml",
+    ".env.template",
+    "compose.yaml",
+    "docker-compose.yaml",
+];
+
+/// Helper to automatically determine the output file path based on common naming conventions.
+pub fn determine_output_path(input: &Path) -> PathBuf {
+    let file_name = input.file_name().unwrap_or_default().to_string_lossy();
+
+    for rule in RULES {
+        if rule.is_exact_match {
+            if file_name == rule.template_suffix {
+                return input.with_file_name(rule.active_suffix);
+            }
+        } else {
+            if file_name == rule.template_suffix {
+                return input.with_file_name(rule.active_suffix);
+            } else if let Some(base) = file_name.strip_suffix(rule.template_suffix) {
+                return input.with_file_name(format!("{}{}", base, rule.active_suffix));
+            }
+        }
+    }
+
+    input.with_extension(format!(
+        "{}.out",
+        input.extension().unwrap_or_default().to_string_lossy()
+    ))
+}
+
+/// Discovers common configuration template files in the current directory.
+pub fn find_input_file() -> Option<PathBuf> {
+    // Priority 1: Exact matches for well-known defaults
+    for &name in DEFAULT_CANDIDATES {
+        let path = PathBuf::from(name);
+        if path.exists() {
+            return Some(path);
+        }
+    }
+
+    // Priority 2: Pattern matches
+    if let Ok(entries) = std::fs::read_dir(".") {
+        let mut fallback = None;
+        for entry in entries.flatten() {
+            let name = entry.file_name();
+            let name_str = name.to_string_lossy();
+
+            for rule in RULES {
+                if !rule.is_exact_match && name_str.ends_with(rule.template_suffix) {
+                    if name_str.contains(".env") || name_str.contains("compose") {
+                        return Some(entry.path());
+                    }
+                    if fallback.is_none() {
+                        fallback = Some(entry.path());
+                    }
+                    break;
+                }
+            }
+        }
+        if let Some(path) = fallback {
+            return Some(path);
+        }
+    }
+
+    None
+}
+
+/// Resolves the active and template paths given an input path.
+/// Returns `(active_path, template_path)`.
+pub fn resolve_paths(input: &Path) -> (Option<PathBuf>, Option<PathBuf>) {
+    let file_name = input.file_name().unwrap_or_default().to_string_lossy();
+    
+    // Check if the input matches any known template pattern
+    let mut is_template = false;
+    for rule in RULES {
+        if rule.is_exact_match {
+            if file_name == rule.template_suffix {
+                is_template = true;
+                break;
+            }
+        } else if file_name.ends_with(rule.template_suffix) {
+            is_template = true;
+            break;
+        }
+    }
+
+    // Fallback template detection
+    if !is_template && (file_name.contains(".example") || file_name.contains(".template")) {
+        is_template = true;
+    }
+
+    if is_template {
+        let expected_active = determine_output_path(input);
+        let active = if expected_active.exists() {
+            Some(expected_active)
+        } else {
+            None
+        };
+        (active, Some(input.to_path_buf()))
+    } else {
+        // Input is treated as the active config
+        let active = Some(input.to_path_buf());
+        let mut template = None;
+        
+        // Try to reverse match rules to find a template
+        for rule in RULES {
+            if rule.is_exact_match {
+                if file_name == rule.active_suffix {
+                    let t = input.with_file_name(rule.template_suffix);
+                    if t.exists() {
+                        template = Some(t);
+                        break;
+                    }
+                }
+            } else if file_name.ends_with(rule.active_suffix) {
+                if file_name == rule.active_suffix {
+                    let t = input.with_file_name(rule.template_suffix);
+                    if t.exists() {
+                        template = Some(t);
+                        break;
+                    }
+                } else if let Some(base) = file_name.strip_suffix(rule.active_suffix) {
+                    let t = input.with_file_name(format!("{}{}", base, rule.template_suffix));
+                    if t.exists() {
+                        template = Some(t);
+                        break;
+                    }
+                }
+            }
+        }
+        
+        // Fallback reverse detection
+        if template.is_none() {
+            let possible_templates = [
+                format!("{}.example", file_name),
+                format!("{}.template", file_name),
+            ];
+            for t in possible_templates {
+                let p = input.with_file_name(t);
+                if p.exists() {
+                    template = Some(p);
+                    break;
+                }
+            }
+        }
+
+        (active, template)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_determine_output_path() {
+        assert_eq!(determine_output_path(Path::new(".env.example")), PathBuf::from(".env"));
+        assert_eq!(determine_output_path(Path::new("compose.yml")), PathBuf::from("compose.override.yml"));
+        assert_eq!(determine_output_path(Path::new("config.template.json")), PathBuf::from("config.json"));
+        assert_eq!(determine_output_path(Path::new("config.example")), PathBuf::from("config.example.out"));
+    }
+}

src/runner.rs

@@ -0,0 +1,282 @@
+use crate::app::{App, InsertVariant, Mode};
+use crate::config::Config;
+use crate::format::FormatHandler;
+use crossterm::event::{self, Event, KeyCode, KeyEvent};
+use ratatui::Terminal;
+use ratatui::backend::Backend;
+use std::io;
+use std::path::Path;
+use tui_input::backend::crossterm::EventHandler;
+
+/// Manages the main application execution loop, event handling, and terminal interaction.
+pub struct AppRunner<'a, B: Backend> {
+    /// Reference to the terminal instance.
+    terminal: &'a mut Terminal<B>,
+    /// Mutable reference to the application state.
+    app: &'a mut App,
+    /// Loaded user configuration.
+    config: &'a Config,
+    /// Path where the final configuration will be saved.
+    output_path: &'a Path,
+    /// Handler for the specific file format (env, json, yaml, toml).
+    handler: &'a dyn FormatHandler,
+    /// Buffer for storing active command entry (e.g., ":w").
+    command_buffer: String,
+    /// Buffer for storing sequence of key presses (e.g., "gg").
+    key_sequence: String,
+}
+
+impl<'a, B: Backend> AppRunner<'a, B>
+where
+    io::Error: From<B::Error>,
+{
+    /// Creates a new runner instance.
+    pub fn new(
+        terminal: &'a mut Terminal<B>,
+        app: &'a mut App,
+        config: &'a Config,
+        output_path: &'a Path,
+        handler: &'a dyn FormatHandler,
+    ) -> Self {
+        Self {
+            terminal,
+            app,
+            config,
+            output_path,
+            handler,
+            command_buffer: String::new(),
+            key_sequence: String::new(),
+        }
+    }
+
+    /// Starts the main application loop.
+    pub fn run(&mut self) -> io::Result<()> {
+        while self.app.running {
+            self.terminal
+                .draw(|f| crate::ui::draw(f, self.app, self.config))?;
+
+            if let Event::Key(key) = event::read()? {
+                self.handle_key_event(key)?;
+            }
+        }
+        Ok(())
+    }
+
+    /// Primary dispatcher for all keyboard events.
+    fn handle_key_event(&mut self, key: KeyEvent) -> io::Result<()> {
+        match self.app.mode {
+            Mode::Normal => self.handle_normal_mode(key),
+            Mode::Insert => self.handle_insert_mode(key),
+            Mode::Search => self.handle_search_mode(key),
+        }
+    }
+
+    /// Handles keys in Normal mode, separating navigation from command entry.
+    fn handle_normal_mode(&mut self, key: KeyEvent) -> io::Result<()> {
+        if !self.command_buffer.is_empty() {
+            self.handle_command_mode(key)
+        } else {
+            self.handle_navigation_mode(key)
+        }
+    }
+
+    /// Logic for entering and executing ":" style commands.
+    fn handle_command_mode(&mut self, key: KeyEvent) -> io::Result<()> {
+        match key.code {
+            KeyCode::Enter => {
+                let cmd = self.command_buffer.clone();
+                self.command_buffer.clear();
+                self.execute_command(&cmd)
+            }
+            KeyCode::Esc => {
+                self.command_buffer.clear();
+                self.app.status_message = None;
+                Ok(())
+            }
+            KeyCode::Backspace => {
+                self.command_buffer.pop();
+                self.sync_command_status();
+                Ok(())
+            }
+            KeyCode::Char(c) => {
+                self.command_buffer.push(c);
+                self.sync_command_status();
+                Ok(())
+            }
+            _ => Ok(()),
+        }
+    }
+
+    /// Handles primary navigation (j/k) and transitions to insert or command modes.
+    fn handle_navigation_mode(&mut self, key: KeyEvent) -> io::Result<()> {
+        if let KeyCode::Char(c) = key.code {
+            self.key_sequence.push(c);
+
+            // Collect all configured keybinds
+            let binds = [
+                (&self.config.keybinds.down, "down"),
+                (&self.config.keybinds.up, "up"),
+                (&self.config.keybinds.edit, "edit"),
+                (&self.config.keybinds.edit_append, "edit_append"),
+                (&self.config.keybinds.edit_substitute, "edit_substitute"),
+                (&self.config.keybinds.search, "search"),
+                (&self.config.keybinds.next_match, "next_match"),
+                (&self.config.keybinds.previous_match, "previous_match"),
+                (&self.config.keybinds.jump_top, "jump_top"),
+                (&self.config.keybinds.jump_bottom, "jump_bottom"),
+                (&self.config.keybinds.append_item, "append_item"),
+                (&self.config.keybinds.prepend_item, "prepend_item"),
+                (&self.config.keybinds.delete_item, "delete_item"),
+                (&self.config.keybinds.undo, "undo"),
+                (&"a".to_string(), "add_missing"),
+                (&":".to_string(), "command"),
+                (&"q".to_string(), "quit"),
+            ];
+
+            let mut exact_match = None;
+            let mut prefix_match = false;
+
+            for (bind, action) in binds.iter() {
+                if bind == &&self.key_sequence {
+                    exact_match = Some(*action);
+                    break;
+                } else if bind.starts_with(&self.key_sequence) {
+                    prefix_match = true;
+                }
+            }
+
+            if let Some(action) = exact_match {
+                self.key_sequence.clear();
+                match action {
+                    "down" => self.app.next(),
+                    "up" => self.app.previous(),
+                    "edit" => self.app.enter_insert(InsertVariant::Start),
+                    "edit_append" => self.app.enter_insert(InsertVariant::End),
+                    "edit_substitute" => self.app.enter_insert(InsertVariant::Substitute),
+                    "search" => {
+                        self.app.mode = Mode::Search;
+                        self.app.search_query.clear();
+                        self.app.status_message = Some(format!("{} ", self.config.keybinds.search));
+                    }
+                    "next_match" => self.app.jump_next_match(),
+                    "previous_match" => self.app.jump_previous_match(),
+                    "jump_top" => self.app.jump_top(),
+                    "jump_bottom" => self.app.jump_bottom(),
+                    "append_item" => self.app.add_array_item(true),
+                    "prepend_item" => self.app.add_array_item(false),
+                    "delete_item" => self.app.delete_selected(),
+                    "undo" => self.app.undo(),
+                    "add_missing" => {
+                        self.app.save_undo_state();
+                        self.add_missing_item();
+                    }
+                    "command" => {
+                        self.command_buffer.push(':');
+                        self.sync_command_status();
+                    }
+                    "quit" => self.app.running = false,
+                    _ => {}
+                }
+            } else if !prefix_match {
+                // Not an exact match and not a prefix for any bind, clear and restart seq
+                self.key_sequence.clear();
+                self.key_sequence.push(c);
+            }
+        } else {
+            // Non-character keys reset the sequence buffer
+            self.key_sequence.clear();
+            match key.code {
+                KeyCode::Down => self.app.next(),
+                KeyCode::Up => self.app.previous(),
+                KeyCode::Enter => self.save_file()?,
+                KeyCode::Esc => self.app.status_message = None,
+                _ => {}
+            }
+        }
+        Ok(())
+    }
+
+    /// Adds a missing item from the template to the active configuration.
+    fn add_missing_item(&mut self) {
+        if let Some(var) = self.app.vars.get_mut(self.app.selected) {
+            if var.status == crate::format::ItemStatus::MissingFromActive {
+                var.status = crate::format::ItemStatus::Present;
+                if !var.is_group {
+                    var.value = var.template_value.clone();
+                }
+                self.app.sync_input_with_selected();
+            }
+        }
+    }
+
+    /// Delegates key events to the `tui_input` handler during active editing.
+    fn handle_insert_mode(&mut self, key: KeyEvent) -> io::Result<()> {
+        match key.code {
+            KeyCode::Esc | KeyCode::Enter => {
+                self.app.enter_normal();
+            }
+            _ => {
+                self.app.input.handle_event(&Event::Key(key));
+            }
+        }
+        Ok(())
+    }
+
+    /// Handles search mode key events.
+    fn handle_search_mode(&mut self, key: KeyEvent) -> io::Result<()> {
+        match key.code {
+            KeyCode::Enter | KeyCode::Esc => {
+                self.app.mode = Mode::Normal;
+                self.app.status_message = None;
+            }
+            KeyCode::Backspace => {
+                self.app.search_query.pop();
+                self.app.status_message = Some(format!("{}{}", self.config.keybinds.search, self.app.search_query));
+                self.app.jump_next_match();
+            }
+            KeyCode::Char(c) => {
+                self.app.search_query.push(c);
+                self.app.status_message = Some(format!("{}{}", self.config.keybinds.search, self.app.search_query));
+                self.app.jump_next_match();
+            }
+            _ => {}
+        }
+        Ok(())
+    }
+
+    /// Logic to map command strings (like ":w") to internal application actions.
+    fn execute_command(&mut self, cmd: &str) -> io::Result<()> {
+        if cmd == self.config.keybinds.save {
+            self.save_file()
+        } else if cmd == self.config.keybinds.quit {
+            self.app.running = false;
+            Ok(())
+        } else if cmd == ":wq" {
+            self.save_file()?;
+            self.app.running = false;
+            Ok(())
+        } else {
+            self.app.status_message = Some(format!("Unknown command: {}", cmd));
+            Ok(())
+        }
+    }
+
+    /// Attempts to write the current app state to the specified output file.
+    fn save_file(&mut self) -> io::Result<()> {
+        if self.handler.write(self.output_path, &self.app.vars).is_ok() {
+            self.app.status_message = Some(format!("Saved to {}", self.output_path.display()));
+        } else {
+            self.app.status_message = Some("Error saving file".to_string());
+        }
+        Ok(())
+    }
+
+    /// Synchronizes the status bar display with the active command buffer.
+    fn sync_command_status(&mut self) {
+        if self.command_buffer.is_empty() {
+            self.app.status_message = None;
+        } else {
+            self.app.status_message = Some(self.command_buffer.clone());
+        }
+    }
+}

src/ui.rs

@@ -3,148 +3,311 @@ use crate::config::Config;
 use ratatui::{
     Frame,
     layout::{Constraint, Direction, Layout},
-    style::{Color, Modifier, Style},
+    style::{Modifier, Style},
     text::{Line, Span},
-    widgets::{Block, Borders, List, ListItem, ListState, Paragraph},
+    widgets::{Block, BorderType, Borders, List, ListItem, ListState, Paragraph},
 };
 
-// Catppuccin Mocha Palette
+/// Renders the main application interface using ratatui.
-const MANTLE: Color = Color::Rgb(24, 24, 37);
+pub fn draw(f: &mut Frame, app: &mut App, config: &Config) {
-const BASE: Color = Color::Rgb(30, 30, 46);
+    let theme = &config.theme;
-const TEXT: Color = Color::Rgb(205, 214, 244);
-const BLUE: Color = Color::Rgb(137, 180, 250);
-const GREEN: Color = Color::Rgb(166, 227, 161);
-const SURFACE1: Color = Color::Rgb(69, 71, 90);
-
-pub fn draw(f: &mut Frame, app: &mut App, _config: &Config) {
     let size = f.area();
 
-    // Theming (defaults to Mocha, can be extended later via _config)
+    // Render the main background (optional based on transparency config).
-    let bg_color = BASE;
+    if !theme.transparent {
-    let fg_color = TEXT;
+        f.render_widget(
-    let highlight_color = BLUE;
+            Block::default().style(Style::default().bg(theme.bg_normal())),
-    let insert_color = GREEN;
+            size,
+        );
+    }
 
-    // Background
+    // Horizontal layout with 1-character side margins.
-    let block = Block::default().style(Style::default().bg(bg_color).fg(fg_color));
+    let outer_layout = Layout::default()
-    f.render_widget(block, size);
+        .direction(Direction::Horizontal)
-
-    let chunks = Layout::default()
-        .direction(Direction::Vertical)
         .constraints([
-            Constraint::Min(3),    // List
+            Constraint::Length(1),
-            Constraint::Length(3), // Input area
+            Constraint::Min(0),
-            Constraint::Length(1), // Status bar
+            Constraint::Length(1),
         ])
         .split(size);
 
-    // List
+    // Vertical layout for the main UI components.
+    let chunks = Layout::default()
+        .direction(Direction::Vertical)
+        .constraints([
+            Constraint::Length(1), // Top margin
+            Constraint::Min(3),    // Main list
+            Constraint::Length(3), // Focused input field
+            Constraint::Length(1), // Spacer
+            Constraint::Length(1), // Status bar
+        ])
+        .split(outer_layout[1]);
+
+    // Build the interactive list of configuration variables.
+    let matching_indices = app.matching_indices();
     let items: Vec<ListItem> = app
         .vars
         .iter()
         .enumerate()
         .map(|(i, var)| {
-            let style = if i == app.selected {
+            let is_selected = i == app.selected;
-                Style::default()
+            let is_match = matching_indices.contains(&i);
-                    .fg(bg_color)
+
-                    .bg(highlight_color)
+            // Indentation based on depth
-                    .add_modifier(Modifier::BOLD)
+            let indent = "  ".repeat(var.depth);
+            let prefix = if var.is_group { "+ " } else { "  " };
+
+            // Determine colors based on depth
+            let depth_color = if is_selected {
+                theme.bg_normal()
             } else {
-                Style::default().fg(fg_color)
+                match var.depth % 4 {
+                    0 => theme.tree_depth_1(),
+                    1 => theme.tree_depth_2(),
+                    2 => theme.tree_depth_3(),
+                    3 => theme.tree_depth_4(),
+                    _ => theme.fg_normal(),
+                }
             };
 
-            let content = format!(" {} = {} ", var.key, var.value);
+            // Determine colors based on status and selection
-            ListItem::new(Line::from(content)).style(style)
+            let text_color = if is_selected {
+                theme.fg_highlight()
+            } else {
+                match var.status {
+                    crate::format::ItemStatus::MissingFromActive if !var.is_group => theme.fg_dimmed(),
+                    crate::format::ItemStatus::Modified => theme.fg_modified(),
+                    _ => theme.fg_normal(),
+                }
+            };
+
+            let key_style = if is_selected {
+                Style::default()
+                    .fg(theme.fg_highlight())
+                    .add_modifier(Modifier::BOLD)
+            } else if is_match {
+                Style::default()
+                    .fg(theme.bg_search())
+                    .add_modifier(Modifier::UNDERLINED)
+            } else if var.status == crate::format::ItemStatus::MissingFromActive && !var.is_group {
+                Style::default()
+                    .fg(theme.fg_dimmed())
+                    .add_modifier(Modifier::DIM)
+            } else {
+                Style::default().fg(depth_color)
+            };
+
+            let mut key_spans = vec![
+                Span::raw(indent),
+                Span::styled(prefix, Style::default().fg(theme.border_normal())),
+                Span::styled(&var.key, key_style),
+            ];
+
+            // Add status indicator if not present (only for leaf variables)
+            if !var.is_group {
+                match var.status {
+                    crate::format::ItemStatus::MissingFromActive => {
+                        let missing_style = if is_selected {
+                            Style::default().fg(theme.fg_highlight()).add_modifier(Modifier::BOLD)
+                        } else {
+                            Style::default().fg(theme.fg_warning()).add_modifier(Modifier::BOLD)
+                        };
+                        key_spans.push(Span::styled(" (missing)", missing_style));
+                    }
+                    crate::format::ItemStatus::Modified => {
+                        if !is_selected {
+                            key_spans.push(Span::styled(" (*)", Style::default().fg(theme.fg_modified())));
+                        }
+                    }
+                    _ => {}
+                }
+            }
+
+            let item_style = if is_selected {
+                Style::default().bg(theme.bg_highlight())
+            } else {
+                Style::default().fg(text_color)
+            };
+
+            if var.is_group {
+                ListItem::new(Line::from(key_spans)).style(item_style)
+            } else {
+                // Show live input text for the selected item if in Insert mode.
+                let val = if is_selected && matches!(app.mode, Mode::Insert) {
+                    app.input.value()
+                } else {
+                    var.value.as_deref().unwrap_or("")
+                };
+
+                let value_style = if is_selected {
+                    Style::default().fg(theme.fg_highlight())
+                } else {
+                    Style::default().fg(theme.fg_normal())
+                };
+
+                let mut val_spans = vec![
+                    Span::raw(format!("{}    └─ ", "  ".repeat(var.depth))),
+                    Span::styled(val, value_style),
+                ];
+
+                if let Some(t_val) = &var.template_value {
+                    if Some(t_val) != var.value.as_ref() {
+                        let t_style = if is_selected {
+                            Style::default().fg(theme.bg_normal()).add_modifier(Modifier::DIM)
+                        } else {
+                            Style::default().fg(theme.fg_dimmed()).add_modifier(Modifier::ITALIC)
+                        };
+                        val_spans.push(Span::styled(format!(" [Def: {}]", t_val), t_style));
+                    }
+                }
+
+                ListItem::new(vec![Line::from(key_spans), Line::from(val_spans)]).style(item_style)
+            }
         })
         .collect();
 
-    let list = List::new(items)
+    let list = List::new(items).block(
-        .block(
         Block::default()
             .borders(Borders::ALL)
-                .title(" Environment Variables ")
+            .border_type(BorderType::Rounded)
-                .border_style(Style::default().fg(SURFACE1)),
+            .title(" Config Variables ")
-        )
+            .title_style(
-        .highlight_style(
                 Style::default()
-                .fg(bg_color)
+                    .fg(theme.fg_accent())
-                .bg(highlight_color)
                     .add_modifier(Modifier::BOLD),
+            )
+            .border_style(Style::default().fg(theme.border_normal())),
     );
 
     let mut state = ListState::default();
     state.select(Some(app.selected));
-    f.render_stateful_widget(list, chunks[0], &mut state);
+    f.render_stateful_widget(list, chunks[1], &mut state);
 
-    // Input Area
+    // Render the focused input area.
     let current_var = app.vars.get(app.selected);
-    let input_title = if let Some(var) = current_var {
+    let mut input_title = " Input ".to_string();
-        if var.default_value.is_empty() {
+    let mut extra_info = String::new();
-            format!(" Editing: {} ", var.key)
+
+    if let Some(var) = current_var {
+        if var.is_group {
+            input_title = format!(" Group: {} ", var.path);
         } else {
-            format!(" Editing: {} (Default: {}) ", var.key, var.default_value)
+            input_title = format!(" Editing: {} ", var.path);
+            if let Some(t_val) = &var.template_value {
+                extra_info = format!("  [Template: {}]", t_val);
+            }
+        }
+    }
+
+    let input_border_color = match app.mode {
+        Mode::Insert => theme.border_active(),
+        Mode::Normal | Mode::Search => theme.border_normal(),
+    };
+
+    let input_text = app.input.value();
+    let cursor_pos = app.input.visual_cursor();
+
+    // Show template value in normal mode if it differs
+    let display_text = if let Some(var) = current_var {
+        if var.is_group {
+            "<group>".to_string()
+        } else if matches!(app.mode, Mode::Normal) {
+            format!("{}{}", input_text, extra_info)
+        } else {
+            input_text.to_string()
         }
     } else {
-        " Input ".to_string()
+        input_text.to_string()
     };
 
-    let input_color = match app.mode {
+    let input = Paragraph::new(display_text)
-        Mode::Insert => insert_color,
+        .style(Style::default().fg(theme.fg_normal()))
-        Mode::Normal => SURFACE1,
-    };
-
-    let input_text = if let Some(var) = current_var {
-        var.value.as_str()
-    } else {
-        ""
-    };
-
-    let input = Paragraph::new(input_text)
-        .style(Style::default().fg(fg_color))
         .block(
             Block::default()
                 .borders(Borders::ALL)
+                .border_type(BorderType::Rounded)
                 .title(input_title)
-                .border_style(Style::default().fg(input_color)),
+                .title_style(
+                    Style::default()
+                        .fg(theme.fg_accent()) // Make title pop
+                        .add_modifier(Modifier::BOLD),
+                )
+                .border_style(Style::default().fg(input_border_color)),
         );
-    f.render_widget(input, chunks[1]);
+    f.render_widget(input, chunks[2]);
 
+    // Position the terminal cursor correctly when in Insert mode.
     if let Mode::Insert = app.mode {
-        let input_area = chunks[1];
-        // Cursor positioning
         f.set_cursor_position(ratatui::layout::Position::new(
-            input_area.x + 1 + input_text.chars().count() as u16,
+            chunks[2].x + 1 + cursor_pos as u16,
-            input_area.y + 1,
+            chunks[2].y + 1,
         ));
     }
 
-    // Status bar
+    // Render the modern pill-style status bar.
-    let status_style = Style::default().bg(MANTLE).fg(fg_color);
+    let (mode_str, mode_style) = match app.mode {
-    let mode_str = match app.mode {
+        Mode::Normal => (
-        Mode::Normal => " NORMAL ",
+            " NORMAL ",
-        Mode::Insert => " INSERT ",
+            Style::default()
-    };
+                .bg(theme.bg_highlight())
-    let mode_style = match app.mode {
+                .fg(theme.bg_normal())
-        Mode::Normal => Style::default()
-            .bg(BLUE)
-            .fg(bg_color)
                 .add_modifier(Modifier::BOLD),
-        Mode::Insert => Style::default()
+        ),
-            .bg(GREEN)
+        Mode::Insert => (
-            .fg(bg_color)
+            " INSERT ",
+            Style::default()
+                .bg(theme.bg_active())
+                .fg(theme.bg_normal())
                 .add_modifier(Modifier::BOLD),
+        ),
+        Mode::Search => (
+            " SEARCH ",
+            Style::default()
+                .bg(theme.bg_search())
+                .fg(theme.bg_normal())
+                .add_modifier(Modifier::BOLD),
+        ),
     };
 
-    let status_msg = app
+    let status_msg = if let Some(msg) = &app.status_message {
-        .status_message
+        msg.clone()
-        .as_deref()
+    } else {
-        .unwrap_or(" j/k: navigate | i: edit | :w/Enter: save | q/:q: quit ");
+        let kb = &config.keybinds;
+        match app.mode {
+            Mode::Normal => {
+                let mut parts = vec![
+                    format!("{}/{} move", kb.down, kb.up),
+                    format!("{}/{} jump", kb.jump_top, kb.jump_bottom),
+                    format!("{} search", kb.search),
+                ];
+                if !app.selected_is_group() {
+                    parts.push(format!("{}/{}/{} edit", kb.edit, kb.edit_append, kb.edit_substitute));
+                }
+                if app.selected_is_missing() {
+                    parts.push(format!("{} add", "a")); // 'a' is currently hardcoded in runner
+                }
+                if app.selected_is_array() {
+                    parts.push(format!("{}/{} array", kb.append_item, kb.prepend_item));
+                }
+                parts.push(format!("{} del", kb.delete_item));
+                parts.push(format!("{} undo", kb.undo));
+                parts.push(format!("{} save", kb.save));
+                parts.push(format!("{} quit", kb.quit));
+                parts.join(" · ")
+            }
+            Mode::Insert => "Esc normal · Enter commit".to_string(),
+            Mode::Search => "Esc normal · type to filter".to_string(),
+        }
+    };
 
     let status_line = Line::from(vec![
         Span::styled(mode_str, mode_style),
-        Span::styled(format!(" {} ", status_msg), status_style),
+        Span::styled(
+            format!(" {} ", status_msg),
+            Style::default().bg(theme.border_normal()).fg(theme.fg_normal()),
+        ),
     ]);
 
-    let status = Paragraph::new(status_line).style(status_style);
+    let status = Paragraph::new(status_line).style(Style::default().bg(theme.border_normal()));
-    f.render_widget(status, chunks[2]);
+    f.render_widget(status, chunks[4]);
 }