From e06cf0c56f3342529f409f2d6a734608f3ebc545 Mon Sep 17 00:00:00 2001
From: Carmine Paolino <carmine@paolino.me>
Date: Sat, 6 Jun 2026 12:33:17 +0200
Subject: [PATCH] Support runtime schema values

---
 lib/ruby_llm/schema/json_output.rb            | 23 ++++++-
 .../schema/robustness/runtime_values_spec.rb  | 60 +++++++++++++++++++
 2 files changed, 81 insertions(+), 2 deletions(-)
 create mode 100644 spec/ruby_llm/schema/robustness/runtime_values_spec.rb

diff --git a/lib/ruby_llm/schema/json_output.rb b/lib/ruby_llm/schema/json_output.rb
index 94c73f2..b5b3bba 100644
--- a/lib/ruby_llm/schema/json_output.rb
+++ b/lib/ruby_llm/schema/json_output.rb
@@ -23,8 +23,8 @@ def to_json_schema
 
         {
           name: @name,
-          description: @description || self.class.description,
-          schema: schema_hash
+          description: resolve_runtime_values(@description || self.class.description),
+          schema: resolve_runtime_values(schema_hash)
         }
       end
 
@@ -32,6 +32,25 @@ def to_json(*_args)
         validate! # Validate schema before generating JSON string
         JSON.pretty_generate(to_json_schema)
       end
+
+      private
+
+      def resolve_runtime_values(value)
+        case value
+        when Proc
+          resolve_runtime_values(evaluate_runtime_value(value))
+        when Hash
+          value.transform_values { |nested_value| resolve_runtime_values(nested_value) }
+        when Array
+          value.map { |nested_value| resolve_runtime_values(nested_value) }
+        else
+          value
+        end
+      end
+
+      def evaluate_runtime_value(value)
+        value.arity.zero? ? instance_exec(&value) : value.call(self)
+      end
     end
   end
 end
diff --git a/spec/ruby_llm/schema/robustness/runtime_values_spec.rb b/spec/ruby_llm/schema/robustness/runtime_values_spec.rb
new file mode 100644
index 0000000..805dc11
--- /dev/null
+++ b/spec/ruby_llm/schema/robustness/runtime_values_spec.rb
@@ -0,0 +1,60 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+RSpec.describe RubyLLM::Schema, "runtime schema values" do
+  it "evaluates proc-backed values when rendering JSON schema" do
+    schema_class = Class.new(described_class) do
+      def initialize(user_names:)
+        super()
+        @user_names = user_names
+      end
+
+      string :name, enum: -> { @user_names }
+    end
+
+    first_schema = schema_class.new(user_names: %w[Alice Bob]).to_json_schema
+    second_schema = schema_class.new(user_names: %w[Carol]).to_json_schema
+
+    expect(first_schema[:schema][:properties][:name][:enum]).to eq(%w[Alice Bob])
+    expect(second_schema[:schema][:properties][:name][:enum]).to eq(%w[Carol])
+    expect(schema_class.properties[:name][:enum]).to be_a(Proc)
+  end
+
+  it "evaluates runtime values inside nested schemas" do
+    schema_class = Class.new(described_class) do
+      def initialize(user_names:)
+        super()
+        @user_names = user_names
+      end
+
+      array :users do
+        object do
+          string :name, enum: -> { @user_names }
+        end
+      end
+    end
+
+    output = schema_class.new(user_names: %w[Alice Bob]).to_json_schema
+    name_schema = output[:schema][:properties][:users][:items][:properties][:name]
+
+    expect(name_schema[:enum]).to eq(%w[Alice Bob])
+  end
+
+  it "supports procs that receive the schema instance" do
+    schema_class = Class.new(described_class) do
+      attr_reader :allowed_roles
+
+      def initialize(allowed_roles:)
+        super()
+        @allowed_roles = allowed_roles
+      end
+
+      string :role, enum: ->(schema) { schema.allowed_roles.dup }
+    end
+
+    output = schema_class.new(allowed_roles: %w[admin user]).to_json_schema
+
+    expect(output[:schema][:properties][:role][:enum]).to eq(%w[admin user])
+  end
+end