diff --git a/TEST_DIAGNOSTICS.md b/TEST_DIAGNOSTICS.md
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+# LSP Diagnostic Test Files
+
+These files are designed to trigger LSP diagnostics of all types to test the Paper Tonic Modern colorscheme's diagnostic virtual text colors.
+
+## Test Files
+
+### test-diagnostics.lua
+Lua file with intentional errors for lua_ls (Lua Language Server).
+
+**Expected diagnostics:**
+- **Errors** (red): Undefined variables/functions, type mismatches, invalid operations, wrong argument counts
+- **Warnings** (orange): Unused variables, shadowing, unreachable code, lowercase globals
+- **Hints** (green): Redundant code, style issues
+
+**Note**: lua_ls provides the best mix of diagnostic levels.
+
+### test-diagnostics.php
+PHP file with intentional errors for Intelephense (PHP Language Server).
+
+**Expected diagnostics:**
+- **Errors** (red): Most issues appear as errors by default in Intelephense
+  - Undefined functions/variables
+  - Type mismatches
+  - Wrong argument counts
+  - Invalid method calls
+
+**Note**: Intelephense is strict and reports most issues as errors. To see warnings/hints, configure in `.nvim.lua`:
+```lua
+return {
+  lsp = {
+    intelephense = {
+      settings = {
+        intelephense = {
+          diagnostics = {
+            undefinedSymbols = true,
+            undefinedVariables = true,
+            unusedSymbols = "hint",  -- Show unused as hints
+          }
+        }
+      }
+    }
+  }
+}
+```
+
+### test-diagnostics.js
+JavaScript file with intentional errors for ts_ls (TypeScript Language Server).
+
+**Expected diagnostics:**
+- **Errors** (red): Undefined variables/functions, invalid property access, missing parameters
+- **Warnings** (orange): Unreachable code, type comparison issues, duplicate cases
+- **Hints** (green): const vs let suggestions
+- **Info** (blue): Unnecessary operations
+
+## How to Use
+
+1. Open any test file in Neovim:
+   ```bash
+   nvim test-diagnostics.lua
+   # or
+   nvim test-diagnostics.php
+   # or
+   nvim test-diagnostics.js
+   ```
+
+2. Wait for LSP to attach and analyze the file (1-2 seconds)
+
+3. Check the virtual text diagnostics at the end of lines with issues
+
+4. Use `:LspInfo` to verify the LSP server is attached
+
+## Color Reference
+
+The Paper Tonic Modern colorscheme uses these colors for diagnostics:
+
+- **DiagnosticError** (virtual text): `#d70000` (bright red) on `#ffefef` background
+- **DiagnosticWarn** (virtual text): `#d75f00` (orange) on `#ece0e0` background
+- **DiagnosticInfo** (virtual text): `#8989af` (blue) on `#e0e0ec` background
+- **DiagnosticHint** (virtual text): `#89af89` (green) on `#e0ece0` background
+
+## Testing Checklist
+
+- [ ] Errors show in red with red undercurl
+- [ ] Warnings show in orange with orange undercurl
+- [ ] Hints show in green
+- [ ] Info messages show in blue
+- [ ] Virtual text is readable against light background
+- [ ] Sign column icons show correct colors
+- [ ] Diagnostic floating windows display correctly
+
+## Debug Command
+
+Use the `<leader>hi` keymap to inspect highlight info under cursor and verify diagnostic colors are applied correctly.
diff --git a/test-diagnostics.js b/test-diagnostics.js
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+++ b/test-diagnostics.js
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+/**
+ * Test file for JavaScript/TypeScript LSP diagnostics
+ * Tests error, warning, info, and hint virtual text colors
+ */
+
+// ERROR: Undefined variable
+console.log(undefinedVariable);
+
+// ERROR: Undefined function
+nonexistentFunction();
+
+// WARNING: Unused variable
+const unusedVariable = "I'm never used";
+
+// ERROR: Type error (if using TypeScript or JSDoc)
+/**
+ * @param {string} name
+ * @param {number} age
+ */
+function greet(name, age) {
+  console.log(`Hello ${name}, you are ${age}`);
+}
+greet("Alice", "not a number");  // Type mismatch
+
+// WARNING: Unreachable code
+function earlyReturn() {
+  return "done";
+  console.log("Never executed");  // Unreachable
+}
+
+// ERROR: Invalid property access
+const obj = {};
+console.log(obj.nonexistent.nested.property);
+
+// WARNING: Comparison with different types
+if ("5" == 5) {  // Should use ===
+  console.log("loose equality");
+}
+
+// ERROR: Missing parameter
+greet("Bob");  // Missing age parameter
+
+// INFO: Unnecessary type assertion (TypeScript)
+const num = 123;
+const str = String(num);  // Could be simplified
+
+// HINT: Variable can be const instead of let
+let neverReassigned = "should be const";
+console.log(neverReassigned);
+
+// ERROR: Division by zero (some linters catch this)
+const result = 10 / 0;
+
+// WARNING: Duplicate case label
+const value = 1;
+switch (value) {
+  case 1:
+    console.log("one");
+    break;
+  case 1:  // Duplicate case
+    console.log("one again");
+    break;
+}
+
+// ERROR: Invalid this context
+const obj2 = {
+  name: "test",
+  greet: () => {
+    console.log(this.name);  // Arrow function doesn't bind this
+  }
+};
+
+console.log("JavaScript diagnostic test complete!");
diff --git a/test-diagnostics.lua b/test-diagnostics.lua
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+++ b/test-diagnostics.lua
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+-- Test file for LSP diagnostics - lua_ls
+-- This file intentionally contains different diagnostic levels
+-- to test diagnostic virtual text colors in paper-tonic-modern
+
+-- Define some valid code first
+local valid_function = function()
+  return "valid"
+end
+
+---@diagnostic disable-next-line: unused-local
+local _ = valid_function()
+
+-- ERROR: Undefined global (lua_ls marks this as error)
+print(undefined_global_variable)
+
+-- ERROR: Undefined function
+undefined_function()
+
+-- WARNING: Unused local variable (lua_ls warning level)
+local unused_variable = "I'm never used"
+
+-- WARNING: Lowercase global (should be local)
+lowercase_global = "This should be local or uppercase"
+
+-- HINT: Redundant parentheses (some configs treat as hint)
+local x = (5)
+print(x)
+
+-- ERROR: Wrong number of arguments
+local function takes_two_args(a, b)
+  return a + b
+end
+takes_two_args(1)  -- Missing second argument (lua_ls error)
+
+-- ERROR: Attempting to call a non-function
+local not_a_function = "string"
+not_a_function()
+
+-- WARNING: Shadowing outer local
+local shadow_me = 1
+do
+  local shadow_me = 2  -- Shadows outer local (warning)
+  print(shadow_me)
+end
+
+-- ERROR: Invalid table access
+local empty_table = {}
+print(empty_table.nonexistent.deeply.nested.property)
+
+-- WARNING/HINT: Can be simplified
+if true == true then  -- Redundant comparison
+  print("always true")
+end
+
+-- ERROR: Type annotation mismatch
+---@type string
+local should_be_string = 123  -- Assigning number to string type
+
+-- WARNING: Unreachable code after return
+local function has_dead_code()
+  return "done"
+  print("This will never execute")  -- Unreachable
+end
+
+-- Valid function call
+print(takes_two_args(1, 2))
+
+-- ERROR: Calling vim API that doesn't exist
+vim.nonexistent_function()
+
+-- HINT: Trailing whitespace or style issues (if configured)
+local with_trailing_space = "value"   
+print(with_trailing_space)
+
+-- ERROR: Parameter type mismatch
+---@param name string
+---@param age number
+local function greet(name, age)
+  print("Hello, " .. name .. ", you are " .. age)
+end
+greet(123, "not a number")  -- Wrong types
+
+print("Diagnostic test complete!")
+
diff --git a/test-diagnostics.php b/test-diagnostics.php
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--- /dev/null
+++ b/test-diagnostics.php
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+<?php
+/**
+ * Test file for PHP LSP diagnostics
+ * Tests error, warning, info, and hint virtual text colors
+ * 
+ * Note: Configure Intelephense to show different diagnostic levels:
+ * - diagnostics.undefinedSymbols = true (errors)
+ * - diagnostics.undefinedVariables = true (warnings)
+ * - diagnostics.unusedSymbols = "hint" (hints)
+ */
+
+// Define some valid functions and variables first to avoid cascading errors
+function validFunction(): void {
+    echo "This is valid\n";
+}
+
+$definedVariable = "I exist";
+
+// ERROR: Undefined function
+someUndefinedFunction();
+
+// ERROR: Undefined variable
+echo $completelyUndefined;
+
+// WARNING/HINT: Unused variable (depends on Intelephense config)
+$unused = "Never used anywhere";
+
+// Valid code to separate errors
+validFunction();
+
+// ERROR: Wrong number of arguments
+function requiresTwoArgs(string $a, string $b): void {
+    echo "$a $b\n";
+}
+requiresTwoArgs("only one");  // Missing second argument
+
+// ERROR: Type mismatch
+function expectsString(string $param): void {
+    echo $param;
+}
+expectsString(123);  // Passing int to string parameter
+
+// WARNING: Variable might not be defined in all code paths
+if (rand(0, 1)) {
+    $maybeUndefined = "sometimes defined";
+}
+// Commenting out to reduce errors: echo $maybeUndefined;
+
+// Valid usage
+echo $definedVariable . "\n";
+
+// ERROR: Calling method on non-object
+$notAnObject = "string";
+$notAnObject->someMethod();
+
+// ERROR: Invalid array access (multiple levels)
+$emptyArray = [];
+echo $emptyArray['key']['nested']['deep'];
+
+// Valid function call
+requiresTwoArgs("hello", "world");
+
+// HINT/WARNING: Unreachable code (some configs)
+function hasDeadCode(): string {
+    return "done";
+    echo "This is unreachable";  // Dead code
+}
+
+echo "Test complete!\n";
+