diff --git a/AGENTS.md b/AGENTS.md
index 7fb516e..b086b77 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -149,6 +149,22 @@ test/predicator/
 
 ## Recent Additions (2025)
 
+### Durations and Relative Dates (v3.4.0)
+
+- Natural-language durations and relative time expressions
+- Relative dates: `3d ago`, `2w from now`, `next 1mo`, `last 1y`
+- Date/DateTime arithmetic: `#2024-01-10# + 5d`, `#2024-01-15T10:30:00Z# - 2h`
+- Grammar updates: `duration` and `relative_date` productions
+- Full pipeline support (lexer, parser, compiler, evaluator, string visitor) with tests
+- Examples:
+
+  ```elixir
+  Predicator.evaluate("created_at > 3d ago", %{"created_at" => ~U[2024-01-20 00:00:00Z]})
+  Predicator.evaluate("due_at < 2w from now", %{"due_at" => Date.add(Date.utc_today(), 10)})
+  Predicator.evaluate("#2024-01-10# + 5d = #2024-01-15#", %{})
+  Predicator.evaluate("#2024-01-15T10:30:00Z# - 2h < #2024-01-15T10:30:00Z#", %{})
+  ```
+
 ### Object Literals (v3.1.0 - JavaScript-Style Objects)
 
 - **Syntax Support**: Complete JavaScript-style object literal syntax (`{}`, `{name: "John"}`, `{user: {role: "admin"}}`)
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 11d3742..fa5cf10 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,31 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [3.4.0] - 2025-09-09
+
+### Added
+
+#### Durations and relative date/time arithmetic
+
+- New duration literals and relative date expressions (e.g., `3d ago`, `2w from now`, `next 1mo`, `last 1y`)
+- Date and DateTime arithmetic using durations (e.g., `#2024-01-10# + 5d`, `#2024-01-15T10:30:00Z# - 2h`)
+- Grammar additions: `duration` and `relative_date` productions
+- Full pipeline support (lexer, parser, compiler, evaluator, string visitor) with tests
+
+#### Examples:
+
+```elixir
+Predicator.evaluate("created_at > 3d ago", %{"created_at" => ~U[2024-01-20 00:00:00Z]})
+Predicator.evaluate("due_at < 2w from now", %{"due_at" => Date.add(Date.utc_today(), 10)})
+Predicator.evaluate("#2024-01-10# + 5d = #2024-01-15#", %{})
+Predicator.evaluate("#2024-01-15T10:30:00Z# - 2h < #2024-01-15T10:30:00Z#", %{})
+```
+
+### Documentation
+
+- Updated EBNF grammar in docs
+- Added AGENTS.md with model-agnostic agent guidance; `CLAUDE.md` now references the same content
+
 ## [3.3.0] - 2025-08-31
 
 ### Added
diff --git a/README.md b/README.md
index 570a8a7..5396233 100644
--- a/README.md
+++ b/README.md
@@ -19,6 +19,7 @@ Predicator allows you to safely evaluate user-defined expressions without the se
 - 🔄 **Reversible**: Convert AST back to string expressions with formatting options
 - 🧮 **Arithmetic**: Full arithmetic operations (`+`, `-`, `*`, `/`, `%`) with proper precedence
 - 📅 **Date Support**: Native date and datetime literals with ISO 8601 format
+- ⏳ **Durations & Relative Dates**: Natural-language durations and relative time expressions with date arithmetic
 - 📋 **Lists**: List literals with membership operations (`in`, `contains`)
 - 🧠 **Smart Logic**: Logical operators with proper precedence (`AND`, `OR`, `NOT`)
 - 🔧 **Functions**: Built-in functions for string, numeric, and date operations
@@ -32,7 +33,7 @@ Add `predicator` to your list of dependencies in `mix.exs`:
 ```elixir
 def deps do
   [
-    {:predicator, "~> 3.3"}
+    {:predicator, "~> 3.4"}
   ]
 end
 ```
@@ -58,6 +59,19 @@ true
 iex> Predicator.evaluate!("created_at < #2024-01-15T10:30:00Z#", %{"created_at" => ~U[2024-01-10 09:00:00Z]})
 true
 
+# Durations, relative dates, and date arithmetic
+iex> Predicator.evaluate!("created_at > 3d ago", %{"created_at" => ~U[2024-01-20 00:00:00Z]})
+true
+
+iex> Predicator.evaluate!("due_at < 2w from now", %{"due_at" => Date.add(Date.utc_today(), 10)})
+true
+
+iex> Predicator.evaluate!("#2024-01-10# + 5d = #2024-01-15#", %{})
+true
+
+iex> Predicator.evaluate!("#2024-01-15T10:30:00Z# - 2h < #2024-01-15T10:30:00Z#", %{})
+true
+
 # List literals and membership
 iex> Predicator.evaluate!("role in ['admin', 'manager']", %{"role" => "admin"})
 true
@@ -334,6 +348,9 @@ iex> Predicator.evaluate("'coding' in user.hobbies", list_context)
 - **Booleans**: `true`, `false` (or plain identifiers like `active`, `expired`)
 - **Dates**: `#2024-01-15#` (ISO 8601 date format)
 - **DateTimes**: `#2024-01-15T10:30:00Z#` (ISO 8601 datetime format with timezone)
+- **Durations**: Natural units for time spans (e.g., `3d`, `2h`, `15m`)
+  - In relative expressions: `3d ago`, `2w from now`, `next 1mo`, `last 1y`
+  - In arithmetic: `#2024-01-10# + 5d`, `#2024-01-15T10:30:00Z# - 2h`
 - **Lists**: `[1, 2, 3]`, `['admin', 'manager']` (homogeneous collections)
 - **Objects**: `{}`, `{name: "John", age: 30}`, `{user: {role: "admin"}}` (JavaScript-style object literals)
 - **Identifiers**: `score`, `user_name`, `is_active`, `user.profile.name`, `user['key']`, `items[0]` (variable references with dot notation and bracket notation for nested data)
@@ -554,4 +571,3 @@ mix dialyzer           # Type checking
 ## Documentation
 
 Full documentation is available at [HexDocs](https://hexdocs.pm/predicator).
-
diff --git a/mix.exs b/mix.exs
index d80b69b..0c14589 100644
--- a/mix.exs
+++ b/mix.exs
@@ -2,7 +2,7 @@ defmodule Predicator.MixProject do
   use Mix.Project
 
   @app :predicator
-  @version "3.3.0"
+  @version "3.4.0"
   @description "A secure, non-evaling condition (boolean predicate) engine for end users"
   @source_url "https://github.com/riddler/predicator-ex"
   @deps [